Controversies in Office-Based Surgery

94  Controversies in Office-Based Surgery Shahme Ahamed Farook

KEY POINTS • In the absence of demonstrable pathology (including incipient periodontal disease), the prophylactic removal of wisdom teeth cannot be justified. • Platelet rich plasma (PRP) applied at the time of surgery may have beneficial effects in soft tissue healing, but there is little evidence to suggest any benefit in bone graft healing. • PRP is useful as a surgical glue to improve the handling of particulate bone grafts. • Although socket grafting for ridge preservation may provide a measurable benefit, existing research suggests the

INTRODUCTION Office-based surgery is a common arrangement in the United States but is less common in countries with a more state/ governmental-run health care system. Yet regardless of the country, ambulatory surgery is familiar to most health care systems. Traditionally, office-based surgery has implied dentoalveolar surgery performed under local anesthesia and possibly sedation or general anesthesia. Contemporary office-based surgery, however, could include a variety of orthognathic and cosmetic procedures. Practice of this scope requires the careful integration of pre-assessment, intraoperative techniques, anesthesia, and postoperative pain control. Above all, such practice requires careful patient compliance and a population that actively wants and expects to undergo sometimes complex procedures as a “day case” patient. Central to the success of ambulatory surgery is the organization of the unit. The facility should be a fully equipped surgical center with trained and experienced staff at all levels of the organization. Success also depends on the patient’s being fully informed and consented for the process, the intended operation, and its sequlae, including complications. Standard pain control protocols should exist, as should protocols and materials for how to handle complications. Key components of the protocol for managing complications include the following: • Initial consultation to develop a diagnosis and offer the patient the treatment options. • Written pre-assessment of the patient’s medical status and medications • Written and verbal explanations of the procedure and its expected outcomes

• • • •

benefit is of limited clinical significance when considering risk and cost versus benefit. Apical surgery is often exploratory as well as therapeutic. The treating clinician should be familiar with the causes of persistent pain and infection following endodontic treatment. Patients having ambulatory surgery must have the appropriate preoperative evaluation.  The anesthetic “team” approach can be used to deliver safe and effective office anesthesia.

• Management during the postoperative period and guidance as to when to seek advice • Follow-up arrangements Because many procedures are carried out with the patient under local anesthesia, sedation, and general anesthesia, a skilled and experienced team of anesthesiologist/nurse anesthetist and nursing staff are essential. This type of anesthesia is difficult and demanding and is best undertaken by persons who have a significant commitment to the center. This extends into the postoperative period, with the need to use preemptive analgesia and regular medication appropriate to the procedure. Given the complexity of the subject, an entire textbook could be devoted to ambulatory oral and maxillofacial surgery and related issues, such as anesthetic management, third-party reimbursement, and facility accreditation. Rather than attempt such an undertaking with limited space, this chapter has adopted an evidence-based approach to explore the efficacy of selected procedures commonly performed in present-day ambulatory care practice in the United States. We offer no pretense in suggesting this chapter is a meta-analysis of each subject; rather, we present a literature-based effort to make sense of questions of interest to the contemporary practitioner, including the following: • The routine surgical removal of wisdom teeth • The routine use of platelet rich plasma (PRP) • Socket grafting for preserving bone volume • Clinical decision making regarding periapical surgery (versus extraction and implant placement) • The US approach to ambulatory anesthesia

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PROPHYLACTIC EXTRACTION OF WISDOM TEETH The elective or prophylactic removal of wisdom teeth or third molars is one of the most controversial issues facing contemporary oral and maxillofacial surgeons. Anesthetic and technological innovations coupled with increasing third-party coverage resulted in a tremendous increase in the volume of this type of surgery through the latter half of the twentieth century. The treatment paradigm changed from the removal of symptomatic teeth to a “preventive” approach in which third molars were removed before the development of objective signs and symptoms. In the United States, the increasing volume of surgery was fueled by a reimbursement system that rewards clinicians for performing operative procedures. With health care expenditures in the billions of dollars, third-party payers have questioned the need to electively remove wisdom teeth that are asymptomatic in an effort to prevent future pathological conditions.1 Whereas maxillary wisdom teeth seem less likely to cause problems, the common culprit is the mandibular third molar. When the symptomatic lower teeth are removed, the upper third molars typically are removed in the process, almost as an incidental procedure. The issue is clouded further by the argument that asymptomatic teeth still may have objective indications of a disease process. The body of literature related to this controversy can be subdivided loosely into (1) clinical research assessing the operative procedure and its outcome, (2) health policy research attempting to formulate decision analysis models, and (3) nonintervention studies to assess the outcome of observation rather than surgery. Those in favor of surgery in young adulthood suggest that prophylactic removal prevents disease, the risk of mandibular fracture, and the relapse of orthodontic treatment. Advocates state that there is less operative risk and that postoperative complications are relatively infrequent and less likely to be severe. Opponents counter that although retaining these teeth carries some risk of disease, it is relatively small compared with operative risk, postoperative complications, and the global economic impact of unneeded surgery. They argue that although studies have shown reduced morbidity with earlier removal of third molars, the cost-risk-benefit data do not justify routine surgical removal. Because there seems to be some difference of opinion on opposite sides of the Atlantic, let us examine the various arguments that have been advanced.

In the era of evidence-based medicine, clinicians increasingly are turning to meta-analysis of the existing literature using strict criteria to evaluate the relative worth of a report. The Cochrane Collaboration is a not-for-profit organization dedicated to providing this type of up-to-date, evidence-based health care information. A systematic review using this database, completed in 2012, compared the effect of prophylactic removal versus no treatment of asymptomatic impacted wisdom teeth on lower anterior crowding.8 The authors concluded that there was a lack of strong evidence to support or refute prophylactic removal of wisdom teeth in adolescents, which neither reduces nor prevents late incisor crowding. Given that finding, are there other justifications for prophylactic wisdom tooth removal?

Prevention of Mandibular Fracture

OPINIONS REGARDING PROPHYLACTIC REMOVAL OF THIRD MOLARS

Increased risk for mandibular angle fracture has been cited as grounds for prophylactic removal of lower third molars.9,10 Some authors have claimed that it is even more important to remove the deeply impacted third molar because it weakens the mandible more than the erupted equivalent.11 Much of this argument was fueled by primate research by Reitzik and colleagues, which demonstrated that less force was needed to fracture a mandible containing a third molar.12 The experience with clinical treatment tends to support that premise, for the presence of a wisdom tooth increases the risk of angle fracture two to three times compared with when the wisdom tooth is absent. Remarking that many studies lacked adequate patient numbers for meaningful analysis, Fuselier and colleagues reviewed data from 1210 patients to determine the relationship of third molars and angle fractures and whether impaction versus eruption was an important factor.13 They determined that angle fractures are more likely to occur when a third molar is present but that deep impactions posed no greater risk than erupted teeth. Some evidence suggests that patients with recently removed third molars are at increased risk for mandibular fracture because bone has been removed in the course of surgery.14 The question remaining is: What happens when the mandible receives a blow sufficient to cause fracture? Although this question is virtually impossible to answer with an in vivo study, indirect evidence suggests the site of fracture simply may move to the condyle.15 Given the most recent literature, there appears to be little justification for prophylactically removing mandibular third molars, impacted or erupted, to prevent mandibular angle fractures.

Prevention of Relapse of Orthodontic Treatment

Prevention of Disease

Contemporary US orthodontists often refer adolescent patients for wisdom tooth removal following the completion of treatment. The reason typically cited is “to prevent relapse or return of crowding.” The concern is usually with the lower anterior teeth and impacted mandibular third molars. The possibility of a cause-effect relationship has been a controversial topic in the scientific literature since Robinson’s report in 1859.2 Some earlier retrospective studies have shown less crowding in patients with congenitally missing lower third molars.3,4 Some have suggested that the impacted third molar is more likely to cause relapse than the erupted counterpart.5 Equal opposition comes from authors citing no relationship between wisdom teeth and orthodontic relapse.6,7 How, then, does one decide which report in the literature to believe?

The final indication for prophylactic removal of third molars is to prevent the progression of localized disease. As mentioned previously, some evidence suggests that asymptomatic teeth may have objective signs of progressive disease. In a randomized, prospective longitudinal trial involving young adults, probing depths were measured around asymptomatic erupted third molars with adjacent second molars.16 Nearly two-thirds of the 254 subjects had at least one probing depth greater than 4 mm, and 25% had at least one probing depth greater than 5 mm. Applying the yardstick that probing depths greater than 3 mm indicate a pathological periodontal condition, these findings indicated that this population is somewhat at risk. Skeptics might argue that increased probing depth does not necessarily indicated disease; however, this same sample

CHAPTER 94  Controversies in Office-Based Surgery exhibited serological evidence of disease when crevicular fluid assays were done.17 Furthermore, these indicators were found in crevicular samples taken in the first molar as well, which raises the question of disease progression. These findings coincided with evidence of periodontal pathogens found in this group as identified by chromosomal DNA probes.18 Periodontal pathological conditions were not the only problem found in the sample. Occlusal caries were found in 29% of the patients at the time of enrollment in the study.19 This figure rose to 33% on follow-up. Data analysis indicated that the presence of caries in first and second molars at baseline was highly predictive of the development of third molar caries during the ensuing 3 years. In an effort to assess the effect on older adults, data from the dental component of the Atherosclerosis Risk in Communities Study was reviewed for evidence of periodontal pathological conditions associated with erupted wisdom teeth.20 The data from 6793 persons aged 52 to 74 indicated a 1.5 times higher risk of having probing depth greater than 5 mm on the adjacent second molar. The US studies tend to indicate that the deeply impacted third molar is not the concern, because there is no association with orthodontic relapse and no increased incidence of mandibular angle fracture compared with the erupted counterpart. The minimal risk of cystic or neoplastic pathological conditions hardly justifies surgical removal. The partially erupted or erupted mandibular third molar may present problems. The multi-institutional, longitudinal clinical trial of Elter and colleagues demonstrates some risk of caries and localized periodontal disease.20 Some indication also exists that this disease may be progressive, as indicated by the serological and bacteriological evidence of disease farther forward in the mouth. Multiple reports of the relationship between periodontal pathological conditions and systemic disease have been made. Beck and Offenbacher concluded that cumulative evidence supports, but does not necessarily prove, a cause-effect relationship between periodontal and atherosclerotic cardiovascular disease.21 Given the transition toward managing periodontal pathological conditions as an infectious or transmissible disease, with possible systemic consequences, there may be reason to follow these patients more closely for periodontal management or extraction if indicated.

Summary Although there is general worldwide agreement regarding the removal of pathologically involved third molars, there is a noticeable lack of sound data to support the risk versus benefit of taking a noninterventional approach when considering disease-free teeth. The American Association of Oral and Maxillofacial Surgeons has refined and developed the National Institutes of Health consensus criteria to include up to 20 indications for removal of third molars. One should note, however, that preventive removal of disease-free teeth is indicated only for “patients with medical or surgical conditions or treatments (for example, organ transplants and radiation therapy).”22 In the United Kingdom (UK), opinion increasingly is favoring the retention of asymptomatic, disease-free third molars. This trend has been borne out in several studies examining differences of opinion between groups of referring general practitioners and surgeons regarding the need for surgery. In one study, 24 clinicians, six surgeons, and six general practitioners each from Glasgow and Hong Kong were asked to review

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the panoramic films of 21 patients having asymptomatic, impacted lower third molars.23 Each clinician gave a recommendation regarding removal versus observation of the tooth in question. The Hong Kong group suggested removal in 71% of the cases, whereas surgery was recommended only 12% of the time by the Glasgow clinicians. In addition to cultural differences, economic differences were suggested as a primary factor. The Glasgow clinicians worked under the National Health Service system, whereas the Hong Kong group practiced in a fee-for-service setting. A second study comparing Welsh and Swedish clinicians produced similar results.24 General dental practitioners and oral surgeons in Sweden and Wales were asked to decide whether third molars should be removed based on a review of standardized radiographs and intraoral photographs. They were shown 36 examples of disease-free, asymptomatic teeth chosen for equal distribution considering age, gender, tooth orientation, and degree of impaction. The participants were informed that the third molars had always been and remained disease-free. Despite a wide variation in the specific molars allocated for removal within each group of general dentists, there was no difference in the mean number suggested for removal between the two countries. In contrast, in four cases, removal of molars was suggested at least twice as frequently by Swedish surgeons compared with their Welsh counterparts. The authors remarked that the less interventionist approach among UK oral surgeons may reflect the more authoritative guidelines developed in the UK and the more extensive debate concerning the need for prophylactic removal.

UNITED KINGDOM NATIONAL THIRD MOLAR PROJECT Given the controversy regarding the removal of disease-free third molars and recognizing the tremendous expenditure for the surgery and associated care, the British Association of Oral and Maxillofacial Surgeons in conjunction with the Department of Health undertook a national audit to assess the actual indications given to justify surgery and the type of anesthetic used to complete the treatment.25 Questionnaires completed by consultants revealed that pericoronitis, at 40%, was the most common diagnosis leading to surgical removal. Of the lower third molars removed, 78% were deemed to be symptomatic or diseased. What is noteworthy is that of all third molars identified, 20% were left untreated and an additional 35% of the patients had only a single tooth in question removed. Although the study did not solve the issue of how to handle asymptomatic, disease-free third molars, it dispelled the feeling that excessive surgery was being performed without proper indications.

Cost-Effectiveness of Retention Versus Removal Relatively little research examines the outcome of retention versus removal of disease-free third molars. Published studies are generally some form of decision analysis and fail to consider patient perspective or health service costs. Recognizing this shortcoming, Edwards and colleagues undertook a study to identify the least costly, most effective, and most cost-effective management strategy for asymptomatic, disease-free mandibular third molars.26 They constructed a decision tree model of the outcomes of retention and removal. Probability data for possible outcomes were obtained from a comprehensive literature review and were entered into the decision tree. The cost to

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the National Health Service in treating each outcome was calculated. To add the patient perspective, 100 patients attending the University of Wales Dental Hospital oral surgery clinics rated the effect of each outcome on their life. Mandibular third molar retention was found to be less costly, more effective, and more cost-effective than surgical removal. Sensitivity analysis indicated that the recommendation changed to surgical removal when the probability of pericoronitis, periodontal disease, and caries passed specific thresholds. The authors concluded that mandibular third molar retention would be less costly to the National Health Service, more effective for the patient, and more cost-effective to both parties than removal unless there was a significant likelihood of the patient developing pericoronitis, periodontal disease, and caries. This point of veiw was further reinforced following the introduction of the National Institute for Health and Care Excellence (NICE) guidelines in 2000.

Third Molar Surgery and Quality of Life The 1990s saw a huge increase in research on the impact of health care on the patient’s quality of life. To paraphrase the sage Persian physician Ibn Sina (980-1037 AD), “The cure of a disease must never be worse than the disease itself.” To that end, the effect of wisdom tooth removal has been the subject of several studies. Savin and Ogden reported results from 39 patients who completed questionnaires the day after and 7 days following third molar removal.27 Patients were asked to use a four-point scale to describe how they felt about the level of physical discomfort, oral and vocal function, their appearance, and social interaction. Not surprisingly, given the timing of the inquiry, results indicated that third molar affected several aspects of quality of life. The fact that there was little improvement during the period of the study indicates that the adverse effects of this operation would seem frequently to persist beyond 1 week. Although none of the patients would need third molar removal again, the authors hoped that a willingness to repeat the procedure might indicate the experience had not been totally unacceptable. This may have relevance when removing wisdom teeth in two appointments (one side at a time) with the use of local anesthesia. Giving an indication of their level of discomfort, one-third of the sample stated they would not wish to repeat the experience. Furthermore, almost 20% of patients would not recommend this treatment to others. A Van Wijk and colleagues study also shows that the short-term consequences of third molar surgery have a strong effect on patients’ quality of life with postoperative complications substantially amplifying this effect.28 These results would seem to call into question the acceptability of prophylactic removal and emphasizes the need to ensure that there is at least one indication for surgery. In a prospective study, McGrath and colleagues examined 100 patients’ perceptions of changes in oral health–related quality of life over a 6-month period following wisdom tooth removal.29 Patients kept a journal of life quality changes each postoperative day for 7 days and were contacted at 1, 3, and 6 months following treatment. Variations in changes in life quality between patients with previously symptomatic and asymptomatic third molars were assessed using a nonparametric statistical test for two independent groups. Those who previously reported having symptoms experienced a greater improvement in oral health–related quality of life compared with patients who were previously asymptomatic. Not surprisingly, this suggests that

patients with previous pericoronitis are likely to benefit most from third molar surgery. This lends support to clinical guidelines that discourage the removal of asymptomatic third molars. However, further case-control studies are required to draw comprehensive conclusions regarding the impact of oral health on life quality among patients with treated and untreated asymptomatic third molars over time.

Summary Flick concluded that analysis of the literature does not answer the questions surrounding impacted, nondiseased third molars with any degree of confidence.1 He points to a need for large population-based studies to provide practitioners with data to help them decide when intervention is indicated and when it is not. Little agreement exists on how many third molars are being removed for so-called prophylactic reasons. The studies that are available on the nonintervention course are few and have flaws. The studies that argue against prophylactic removal largely are based on statistical models that are questionable as a basis for clinical decision making. Furthermore, the effects of provider supply and the nature of reimbursement must be considered as an integral part of the controversy. In his paper making the case against routine removal, Hicks stated that in the absence of scientifically sound data and objective analysis of cost, risk, and benefit ratios, clinicians make treatment decisions on a precarious and whimsical foundation constructed from personal opinion and bias, anecdotes, and self-serving ideologies.30 The prudent clinician may be well advised to remember the Hippocratic oath: “Do no harm.”

PLATELET RICH PLASMA A multitude of biomedical developments have affected maxillofacial surgery during the last two decades of the twentieth century. None, perhaps, has remained so controversial and unresolved as the therapeutic value of concentrated platelets, commonly called platelet rich plasma (PRP), in surgical care. Although the role of platelets in hemostasis is well established, the concept of using autologous PRP concentrate as an intraoperative adjunct to control hemorrhage and stabilize bone grafts was introduced in the early 1990s.31 The clinicians were trying to avoid the potential complications of disease transmission and immunological reactions associated with the use of fibrin glue prepared from pooled blood. Whitman and colleagues were among the first to suggest the use of PRP in a maxillofacial application.32 Although they described in detail a simplified protocol for collection and preparation and reported on their experience with various applications, there was little discussion suggesting any advantage in accelerated wound healing. In fact, not until the final sentence of the paper do the authors cautiously comment that “platelets bring cytokines and growth factors to the site of surgery in a manner that would not occur with fibrin glue.”32 Marx and colleagues were among the first to suggest that PRP not only facilitates graft management at the time of surgery but also significantly enhances bone healing.33 They reported the results of 88 autogenous bone marrow graft reconstructions for mandibular discontinuity defects resulting from tumor surgery. Patients were randomized into a group receiving cancellous marrow grafts alone and a group receiving the graft with PRP added topically and during graft preparation. Machine and manual platelet counts confirmed the increased PRP

CHAPTER 94  Controversies in Office-Based Surgery

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concentration, and monoclonal antibody stains identified the presence of growth factors in the PRP and receptors in the treated graft material. Trephined bone specimens were retrieved at 6 months in the course of implant reconstruction. Histomorphometry of these specimens revealed a trabecular bone area of 55.1% ± 8% for the non-PRP grafts and 74% ± 11% for the PRP-treated grafts. The authors suggested the use of PRP accelerated the rate and degree of bone formation within a graft for at least the first 6 months. This report undoubtedly sparked academic interest, because since that time many investigators have sought to duplicate these results.

reduction of dry sockets, as well as in periodontal/peri-implant defects. The use of PRP has been suggested to allow earlier implant loading and improved osseointegration in healthy bone and in bone compromised by osteoporosis or previous radiation treatment. Because the wound healing factors also affect soft tissue, PRP has been advocated for topical use with connective tissue and free gingival grafts, alloplastic grafts, and various mucosal flaps. Extraoral uses have included application to skin graft recipient and donor sites, fat grafts, and various cosmetic procedures, including laser resurfacing, blepharoplasties, browlifts, and facelifts.

Mechanism of Action

Research Validation

The role platelets play in hemorrhage control is well known. When platelets are activated, a gelatinous structure is formed to aid hemostasis, and (more central to this discussion) woundhealing growth factors are released. Research suggests that these factors produce increased cell mitosis, collagen production, and vascular ingrowth in addition to recruiting macrophages and inducing cellular differentiation. The factors of interest include transforming growth factor-β, platelet-derived growth factor, vascular endothelial growth factor, and the various isomers. The concentrate also contains the cell adhesion protein molecules fibrin, fibronectin, and vitronectin, which aid clotting and serve as a matrix for tissue regeneration. The addition of the growth factors and adhesion molecules in concentration promised tremendous benefit to clinicians concerned with wound healing, and early experience supported this theory.

How much PRP is enough? No one, perhaps, has been more vocal in advancing the case for PRP therapy than Marx.36 Since the influential paper of 1998, he has responded to skeptics with discussions, explanations, and arguments supporting the use of PRP.33 Marx has suggested a dose-response relationship between platelet concentration and the level of wound-healing benefit. He emphasized that a strict protocol is necessary and that only specific machines have the ability to provide the concentration needed to enhance wound healing while keeping the platelets intact.37 He suggested that alternate concentration methods can result in damaged platelets that are less effective. Although Haynesworth and colleagues and Liu and colleagues add credence to this assertion, it has not been supported uniformly with other basic research.38,39 Graziani and colleagues used cell cultures of human osteoblasts and fibroblasts to test the action of various PRP concentrations on cellular proliferation.40 They found the maximal effect resulted from a concentration of 2.5 times normal, with higher levels reducing proliferation. In response to such negative findings, Marx stated that artificially engineered environments fail to replicate the wound as seen in a clinical setting, thereby invalidating any extrapolation to human clinical use. (Note that this premise apparently does not apply to the work of Haynesworth and colleagues and Liu and colleagues.)

Preparation of Platelet Rich Plasma PRP most commonly is produced by collecting a sample of the patient’s venous blood and submitting it to centrifugation to concentrate the platelets. Although alternate systems such as modified filtration techniques have been developed, Weibrich and colleagues have shown that not all devices are capable of producing like amounts of PRP and the associated growth factors.34,35 Current US Food and Drug Administration (FDA)– approved machines are able to process relatively small volumes of blood but are suitable for ambulatory surgical applications. Once the PRP is prepared, the coagulation process is initiated with thrombin/10% calcium chloride for every 1000 units of topical thrombin. Clotting is initiated by simultaneous mixing of the PRP and activator as the materials are expressed out of the dual lumen applicator tip. The activation produces a gelatinous structure containing the important, newly released wound-healing growth factors that can be mixed with the donor bone or applied topically. With the addition of PRP to the graft, fibrin formation binds the loose particulate material to improve handling characteristics and facilitate fixation of the bone graft material to the intended surgical site. If several applications are needed, the syringes of special-purpose may be refilled.

Clinical Application One cannot deny the value of PRP in improving hemostasis and the handling of grafts composed of particulate bone and bone substitutes. In this regard, PRP acts much like the fibrin glue products popularized in the 1980s. Of much greater interest, however, is the potential for PRP to stimulate osteoprogenitor cell activity, resulting in accelerated healing and increased graft volume when using bone and bone substitutes. Advocates cite improved results in continuity defect grafting, sinus lifts, ridge augmentation, socket grafting for ridge preservation, and

Therapeutic Effect The scientific literature is replete with a mix of basic research, animal studies, and clinical reports supporting the hemostatic and wound healing effects of PRP. From his survey of the literature, Marx has stated there is a 9 : 1 ratio of papers supporting PRP efficacy compared with those not doing so.41 Clinicians using PRP almost uniformly remark on the positive soft tissue healing impact. In his 2004 paper, Marx offers “seeing is believing” evidence of enhanced wound healing in split-thickness skin grafts.36 The visual appearance is supported by histological sections comparing a treated versus nontreated site for evidence of epithelial budding and enhanced collagen formation. This is not surprising because one would expect early enhancement of soft tissue wound healing by the growth factors secreted during the 5- to 7-day lifespan of the platelet. The most ardently debated question is not the early soft tissue effect but rather the effect in bone grafting applications. Is this early enhancement of wound healing sustained by cell recruitment to the area; and if so, what is the ultimate impact on graft density and volume? When focused on this particular area, the research findings are mixed and certainly do not overwhelmingly support the use of PRP to enhance bone healing. Gruber and colleagues suggested a positive response with their investigations using cultured human trabecular

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bone-derived cells.42 They found a fiftyfold increase in DNA synthesis when bone cells were cultured in the presence of the platelet factors released or even in microparticles and the actual platelet membranes. Unfortunately, this response does not appear to transpose uniformly to animal studies or the clinical situation. Freymiller and Aghaloo suggested several reasons for equivocal research results, including variation in animal healing response and in nonuniform methods of collection and preparation of PRP.43 Some also have suggested that research failing to support the use of PRP has used animal models in which the blood volume was adequate. Research reports involving human beings are no less equivocal. Numerous clinical reports, case studies, and technical notes are available, but there is a dearth of prospective, randomized, double-blind clinical studies. Aside from the initial paper by Marx and colleagues, there is a scattering of reports supporting the clinical value of PRP in bone healing.33 Camargo and colleagues used a split-mouth design to compare the resolution of infrabony defect using guided tissue regeneration.44 One side was treated with only a resorbable polylactic acid membrane, and the opposite side was treated with particulate bovine bone combined with PRP. Reentry surgery at 6 months confirmed significant defect resolution using both techniques. The sites treated with the bovine bone/PRP combination had better fill, but unfortunately, the research design does not allow determination of whether the result was due to the graft material itself or the addition of PRP. A Cochrane review in 2010 did not identify a positive impact on the clinical outcome following the use of PRP with autogenous bone or bone substitute in sinus lift procedures.45 Khairy and colleagues in 2013 were able to confirm PRP-enriched bone grafts were associated with superior bone density at 6 months post grafting, but this was a randomized clinical trial involving only 15 patients.46 Mancuso and colleagues used a split-mouth design with randomization in treating 117 patients indicated for lower wisdom tooth removal.47 Exclusion factors included history of infection or use of tobacco or oral contraceptives. PRP was added to one site, and the patients were observed at 17, 14, and 30 days by clinicians who were blinded regarding the control and experimental site. The untreated side had nearly a fourfold increase in the number of dry sockets requiring treatment. Although no formal analysis was done, the authors subjectively found more dense bone fill on radiographic follow-up. Thor and colleagues used a randomized split-mouth design in a prospective study involving 19 consecutive patients with atrophic edentulous maxillae in whom grafting in the anterior and posterior region was indicated.48 The test side in the anterior region was grafted with autogenous particulate bone with PRP, and the control side was treated with an onlay graft without the addition of PRP. The posterior regions were treated by autogenous particulate sinus grafting, with only one side having the addition of PRP. At 6 months of healing, eight implants per patient were placed, with 76 implants in test sites and 76 in control sites. After 1 year in function, there was no statistically significant difference in implant survival rate, marginal bone level, or implant stability using resonance frequency analysis. The authors concluded that although there is no effect on graft healing and the success of osseointegration, the handling of particulate graft material is easier with PRP. Positive outcome results in the treatment bisphosphonaterelated osteonecrosis of the jaw (BRONJ) with PRP are trickling

through. Mozzati and colleagues who successfully treated 32 patients with BRONJ by resecting the necrotic bone and primary closure with PRP highlights this as an adjunct future treatment option for BRONJ.49

Summary Clearly the value of PRP for enhancement of bone healing has yet to be proved. Lack of standardization in research design has made it difficult to evaluate the literature fully. Multiple applications have been suggested by advocates, but data are insufficient to state unequivocally which applications have merit. The one study demonstrating a clear therapeutic advantage in bone healing has yet to be corroborated independently.33 The issue is clouded further by the PRP economy that has evolved. Clinician advocates who are “how to” courses espouse the routine use of PRP in clinical care. Multiple manufacturers are involved in producing and promoting the materials needed to use PRP in the office and hospital setting. And it must be noted that PRP is not given away at the time of surgery; a fee is generated for expendables, equipment use, and the adjunctive procedure. Given the widespread enthusiasm related to the use of PRP, how does the prudent clinician reconcile these mixed results regarding efficacy? To be accepted as efficacious, new procedures and treatments need to be proved to have low risk and significant benefit and to be cost-effective. In essence, the new treatment must show a clear therapeutic advantage over the proven traditional methods. Based on sound scientific method, new therapies must be evaluated by a mix of molecular-level studies, animal research, and carefully designed randomized, prospective, double-blind clinical trials. Studies showing clear benefit must be corroborated independently. Despite considerable research in the past decade, debate regarding the therapeutic value of PRP continues in the scientific literature. Evidence exists of enhanced early soft tissue wound healing, which is in keeping with the known lifespan of activated platelets. The value in enhancing bone healing beyond the early stages, however, has not been substantiated. If the prudent, ethical clinician is to practice evidence-based medicine, it is difficult to advocate the use of PRP in bone grafting applications other than to improve handling qualities. As summarized by Schmitz and Hollinger, perhaps a cautious and critical approach to adopting a therapy for which the overall therapeutic effect is still in question is appropriate.50

SOCKET GRAFTING FOR PRESERVING BONE VOLUME Preservation of bone volume following dental extractions is an important concern, especially when an implant-borne restoration is planned in the esthetic zone. Tan and colleagues, who reviewed post-extractional alveolar hard and soft tissue dimensional changes after 6 months, noted that the vertical resorption of the alveolar bone was 11% to 22% and horizontal resorption was 29% to 63%.51 After 3 months of healing, the horizontal resorption of the alveolar bone was 2.2 mm at the crest, and 1.3, 0.59, and 0.3 mm at 3, 6, and 9 mm apical to the crest, respectively. Following premolar extraction, Araujo and Lindhe described two overlapping phases of resorption: an initial reduction in height with bone loss more predominant on the facial aspect, followed by horizontal bone loss with resorption on the buccal and lingual aspects.53 In a clinical

CHAPTER 94  Controversies in Office-Based Surgery situation, this amount of change in height and width may compromise the esthetic result or preclude implant placement altogether unless secondary augmentation procedures are done. Two approaches have been used in recent years to avoid this problem: immediate placement of the implant into the extraction site with or without supplemental grafting, and volume preservation by socket grafting or guided bone regeneration with delayed placement of the implant(s). This discussion is limited to the latter approach. Placing a bone graft or bone substitute at the time of dental extraction is an attractive concept. It aims to maintain the height and width of the alveolus. If achieved, ridge maintenance facilitates the placement of dental implants or, alternatively, could be important should orthodontics be needed later to move teeth into the extraction site. The efficacy of ridge preservation is based on several assumptions: • Significant resorption will occur if nothing is done. • Grafting indeed maintains the needed height and width for the desired time. • The graft material is remodeled into vital bone within a reasonable time. • If an autogenous graft is used, then donor site morbidity is acceptable. • Implant success rates are comparable to placement in native bone. • The risk of adverse consequence with accelerated bone loss is low.

Socket Preservation Technique Socket preservation involves several variations on a common theme. The tooth in question is extracted with as little trauma as possible, often with the assistance of periotomes or root sectioning. The socket is cleared of debris, and if bleeding is insufficient, the socket may be perforated toward the palatal or lingual aspect with a round bur to ensure a good clot. Commonly, a graft of some nature is added to the socket to fill the void or even augment the ridge contour. Once placed, the graft is contained and the site is sealed by primary closure or occlusion with some type of plug or membrane (Figure 94-1). Alternatively, the socket may be covered with some type of semipermeable membrane to block fibrous tissue ingrowth and encourage bone fill. Autogenous Grafts Many surgeons do not use autologous bone, but rather bone substitutes. The evidence regarding donor site morbidity with

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B

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autogenous bone harvesting is considerable. Because hip or tibial plateau sites cannot be justified given the small volume of bone needed, surgeons wanting an autogenous graft usually choose posterior ramus or anterior mandibular symphysis donor sites. Silva and colleagues concluded complications and morbidity were less in the ramus than in symphysis with temporary sensory disturbance the most common complication, noted in both approaches.53 Access is more difficult at the ramus unless one uses a dedicated power trephine system for harvesting. Although more accessible, the use of symphyseal sites is not without morbidity. Raghoebar and colleagues reported that almost half the patients objectively tested following symphyseal graft harvest experienced some degree of altered sensation in the area.54 Other complications such as bleeding, infection, ecchymosis, or dehiscence are uncommon and usually of minor consequence, but they still add to the patient’s perception of the associated morbidity. Occlusive Membranes Because little advantage appears to accrue from the use of autogenous bone, most clinicians performing socket preservation choose to use non-autogenous materials for convenience and to avoid donor site morbidity. The most simplistic approach to attempting ridge preservation is guided bone regeneration using a semipermeable membrane that is resorbable or nonresorbable. In theory, the pore size of the membrane prevents fibrous ingrowth, thus allowing subperiosteal bone growth to take place. A considerable body of research exists on using membranes only in guided bone regeneration for periodontal defects and along with immediate implant placement. However, relatively few well-designed studies have tested the value of the various membranes alone in an extraction model. A gold standard study would compare them all; resorbable and nonresorbable versus an untreated control in a randomized split-mouth study. This has not been done to date. Earlier studies involved the use of expanded polytetrafluoroethylene (e-PTFE) membranes compared with untreated controls. Lekovic and colleagues reported better maintenance of ridge height that was statistically significant compared with no treatment.55 However, the membrane became exposed in 30% of the patients, leading to bone loss comparable to the untreated controls and thus losing any therapeutic advantage. When grafting is performed, membranes have the added advantage of being occlusive or physically containing particulate material immediately following placement. Other materials can be used for socket occlusion, but there seems to be some merit

C

FIG 94-1  Demonstration of socket preservation with bone graft following extraction of a tooth. A, Tooth socket cleared of debris following extraction. B, Autologous bone graft is added to reinforce the ridge. C, Graft is contained and the site is sealed by primary.

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CHAPTER 94  Controversies in Office-Based Surgery

to the semipermeable membrane. Vasilic and colleagues used a split-mouth design to compare ridge preservation in sites grafted with bovine porous bone mineral plus collagen membrane versus bovine porous bone mineral mixed with and covered by an autologous fibrinogen-fibronectin system.56 The 6-month reentry measurements indicated that there was less loss in height and width with the bovine porous bone mineral covered with a collagen membrane. The differences, however, were in the 1- to 2-mm range, which is of questionable clinical significance. Resorbable membranes have the obvious advantage of needing no second-stage surgery for retrieval. As foreign bodies, they invoke a tissue response that may be detrimental to bone formation depending on the type of degradation. Simion and colleagues documented this effect in a study involving immediate implant placement following extraction.57 The two experimental groups had the implant sites covered by polylactic/ polyglycolic acid resorbable membranes or non-resorbable e-PTFE membranes. The control sites had implants placed with no membrane covering. Bone samples were retrieved 6 months following healing using a specially designed bone harvest cover screws. The sites covered with non-resorbable membranes exhibited greater fill with a bone that was denser than the resorbable group. Nevertheless, Lekovic and colleagues found resorbable membranes useful in preventing bone loss compared with no socket occlusion following extraction.58 Membrane stabilization appears to be a factor in ridge preservation. Compared with sites with no stabilization, membrane tacking or suturing reduces the amount of bone loss.59 The lack of any significant bone fill around the control implants in the study by Simion and colleagues suggests the need for some type of occlusive membrane (resorbable or nonresorbable) for immediate implant placement.57 However, other research has not supported this finding. Botticelli and colleagues found membranes of no value in their study involving placement of sandblasted, large-grit, acid-etched surface implants in a dog model.60 The control sites had implants placed in a traditional manner, whereas the test sites had a 1- to 1.25-mm circumferential defect created with a step drill. The test sites were covered with a resorbable membrane or were left uncovered. Ground sections of block biopsies taken 4 months later showed no difference between the membrane and nonmembrane sites. Skeptics likely would point to the small number of implant sites in the study and the fact that bone healing in a dog may vary from that seen in a human being. Titanium occlusive membranes are now starting to be used. There is no current data relating to their efficacy at present but the advantage of it being bio-compatible negates the need for a second surgery. Non-Autogenous Graft Materials When comparing membrane alone versus membrane plus graft, there is some indication that the former may heal with betterquality bone depending on the type of graft material used. A wide spectrum of bottled graft materials is available, and considerable research has been done on the outcome when various types are used. Carmagnola and colleagues compared bone loss in extraction sites treated with a Bio-Gide (Geistlich Group, Zurich, Switzerland) membrane alone and Bio-Gide covering a Bio-Oss graft (Geistlich Group).61 Untreated sockets were used as controls. Ridge preservation was better with membrane plus graft, but the socket contents may be less desirable. Biopsies

taken at the time of implant placement showed well-healed bone in the control and membrane-only groups, whereas the graft plus membrane group had a high percentage of nonvital graft remaining. On average, only 40% of the Bio-Oss particle circumference was in contact with vital bone. Luczyszyn and colleagues reported similar findings using an acellular dermal matrix graft as the occlusive membrane in sites receiving resorbable hydroxyapatite.62 Compared with sites with an acellular dermal matrix graft membrane alone, the grafted sites demonstrated 1 mm less loss of ridge width. However, the reentry specimens taken after 6 months from the grafted group showed residual graft particles with highly vascularized connective tissue surrounding them. The choice of graft or socket filler and of membrane is an important consideration in socket preservation. Artzi and colleages underscored this fact with their comparison of inorganic bovine bone and β-tricalcium phosphate as graft materials in a dog model.63 Both materials were placed in surgically created mandibular defects and with unfilled sites serving as controls. The test and control sites were covered and uncovered with a dual-layer collagen membrane. Specimens were recovered at 3, 6, 12, and 24 months, and histomorphometry was used to assess regenerated bone, residual graft, and volume produced. Complete bone healing occurred in all grafted sites, but in the bovine bone group, residual graft continued to dominate the sites even at 24 months. The β-tricalcium phosphate sites demonstrated a significantly higher bone area fraction of regenerate at all time points. Similar results have been seen in human studies involving bioactive glass material. In a randomized study of extraction socket healing, Froum and colleageus compared the amount of vital bone 6 to 8 months following healing in sites filled with freeze-dried demineralized allograft or bioactive glass xenograft.64 The biopsies taken at the time of implant placement showed significant more bone allograft (13.5%) remaining compared with the bioactive glass (5.5%). Consistent with this finding, the sites grafted with bioactive glass demonstrated a higher percentage of bone regeneration, with the untreated controls and bone allograft sites being remarkably similar. There appears to be a point of diminishing returns, however, in seeking a rapidly replaced filler material. In an attempt to avoid residual nonvital graft material, Serino and colleagues compared ridge preservation and bone quality in extraction sockets grafted with a resorbable polylactide-polyglycolic acid sponge (Fisiograft, Ghimas S.p.A., Italy) versus ungrafted control sites.84 Biopsies taken when implants were placed at 6 months demonstrated lack of residual graft material and regeneration of mature, well-structured bone in test and control sites. The authors furthermore stated the use of Fisiograft prevented or reduced the amount of alveolar resorption following extraction. However, on average there was less than 1 mm between test and control ridge dimensions; this is hardly a clinically significant difference. The concept of rapid graft replacement with native bone is attractive when implant placement is planned. The ability to stimulate a greater quantity of bone fill would be even more desirable. Research involving recombinant bone morphogenetic protein potentially holds promise for the future in a variety of applications requiring bone healing and growth. Howell and colleagues used the socket grafting model to compare ridge preservation and augmentation in two groups having sites grafted with a collagen sponge saturated with recombinant human bone morphogenetic protein 2 (rhBMP-2)/absorbable

CHAPTER 94  Controversies in Office-Based Surgery collagen sponge (ACS).66 The study involved not only the morphological evaluation but also safety during the expected bone induction period, functional results, and long-term safety. The results confirmed the local and systemic safety of the recombinant bone morphogenetic protein; still, variable loss of volume was noted between 1 and 2 months. Augmentation was not achieved. Although the material handled nicely and had no adverse effects, there are certainly more cost-effective means of ridge preservation. Fiorellini and colleagues evaluated the ridge height changes after therapy by computed tomography (CT) reporting statistically significant differences (P = 0.007) when comparing the use of an ACS soaked with 1.50 mg/mL rhBMP-2 with the untreated control group.67

Summary The goal of ridge preservation following extraction in a patient planned for implant reconstruction is difficult to argue. Animal and human studies alike indicate considerable alveolar ridge resorption can occur in the 4 to 6 months following extraction. The question then becomes one of identifying an approach that yields optimal results. Due to the broad variety of employed materials, techniques, defect morphologies, and healing periods, as well as the relatively small sample sizes, meta-analysis or comparative assessment of ARP cannot be made. Consequently no material or method can be claimed to serve superior to another. However, in certain cases guided bone regeneration appeared to be most effective. Occlusive membranes are most effective when combined with some type of graft material to fill the socket. The morbidity of autogenous grafting is difficult to justify unless donor material is being obtained for other augmentation requiring block bone. The allografts and xenografts that provide the best preservation are slow to resorb and reduce the ratio of vital regenerated bone in the implant site. Materials such as bioactive glass and β-tricalcium phosphate resorb more quickly and seem to provide a nice balance between preservation and vital bone regeneration. Resorbable materials such as collagen and polylactic-polyglycolic sponges are least effective in ridge preservation or bone conduction/induction, even when combined with various growth factors that stimulate bone growth. Vignoletti and colleagues concluded that the results of the meta-regression analysis showed that the surgical approach, flapped or flapless, was the most important factor influencing the results.69 Flapped surgical procedures demonstrated a significantly lesser horizontal resorption of the socket when compared to flapless surgeries. It is thought achieving full closure and healing with primary intention, mainly when the socket is filled with a biomaterial or covered with a barrier membrane is of importance. This study also demonstrated that changes in the horizontal dimension have been the ones benefitted most by the socket preservation techniques. No meta-analyses could be performed on implant-related outcomes, post socket preservation procedures due to the lack of sufficient data. The crux of the matter, however, is the ultimate survival rate of implants placed in sites where ridge preservation has been attempted. Is the survival rate as good as implants placed in native bone in the same location, assuming the bone volume that has been maintained is conducive to esthetic restoration? Considering the unfathomable number of dental implants placed in the past 25 to 30 years, it is amazing there is so little published information addressing this issue. Certainly, this is a fertile area for well-designed prospective research.

1455

There is, perhaps, a wider range of studies reporting the survival rate of implants placed in sinus grafts, but these may not be suitable for extrapolation. Regardless of the site, one must consider multiple other variables, including implant design, surface treatment, type of restoration, and site of placement. When considering all studies, the success rate in grafted sinuses varies widely from 36% to 100%.70,71 These findings are clearly not much value in making clinical decisions or obtaining informed patient consent. Norton and Wilson published one of the few studies that provides an indication.72 After delayed placement of 40 gritblasted implants in sites treated with bioactive glass ridge preservation, the authors reported an overall success rate of 88.6% over 2.5 years. This figure was affected by the death of one patient 18 months following implantation and serious illness in another; otherwise, the success rate would have approached that expected for native bone. Minichetti and colleagues reported comparable rates with delayed placement in patients treated with defatted, gamma-radiated allograft.73 Although there is too little research to state conclusively, the longer-lasting graft materials appear to have no adverse effect on implant success rate. Despite the studies showing residual, nonvital graft material up to 24 months following socket preservation, there may be negligible impact on implant integration. At 4 years of follow-up, Prosper and colleagues found comparable success rates in patients having implants placed immediately in sites grafted with resorbable hydroxyapatite compared with nongrafted controls.74 The success rates for both compared favorably with that seen with implants placed in native bone. When faced with the opportunity to graft an extraction site in a suitable patient, how does the clinician decide on technique and materials or whether, in fact, to do anything? Clearly, the clinician cannot cite overwhelming evidence. It might, however, be stated correctly “that if a bone substitute is used, the complications and risks are minimal, and there may be some benefit.”

THE EFFICACY OF SURGICAL ENDODONTICS A common clinical dilemma is how to manage the symptomatic tooth requiring restoration, which represents a significant investment in time and money. The decision may be complicated further if the tooth in question makes the difference between a fixed restoration and a removable partial denture. The advent of dental implantology has made the decision making somewhat easier, albeit no less costly to the patient. The obvious question is how does one decide between endodontic management versus extraction and implant-supported restorations? The following section addresses decision analysis in the context of treatment outcome literature and suggests algorithms to guide clinical care.

Preoperative Planning Although endodontic care is typically successful, in approximately 10% to 15% of the cases symptoms can persist or spontaneously reoccur.75 Many endodontic failures occur 1 year or more following the initial root canal treatment, often complicating a situation in which a definitive restoration already has been placed. This creates a higher “value” for the tooth because it now may be supporting a fixed partial denture. A decision then is needed to determine whether conventional endodontic

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CHAPTER 94  Controversies in Office-Based Surgery

retreatment can be accomplished or whether periapical surgery to extract the tooth with loss of the overlying prosthesis should be pursued. Causes of endodontic failures often can be separated into biological issues such as a persistent infection or technical factors such as a broken instrument in the root canal system (see Figure 94-1). Failure of endodontic treatment is most commonly due to the presence of bacteria within the root canal system with apical leakage. Continued infection also may result from debris displaced out the apex during the initial endodontic treatment. Technical factors alone are a less common indication for surgery, comprising only 3% of the total cases referred for surgery, yet our opinion is that there is a higher success rate in these cases.76 Before surgery, discussions with patients are critical in order for the patient to give appropriate informed consent. The clinician needs to review and document the particular risks of surgery based on the anatomical location (sinus involvement or proximity to the inferior alveolar nerve). One must stress the exploratory nature of periapical surgery to the patient. Depending on the findings at surgery, a limited root resection with retrograde restoration may be required. However, the patient and surgeon also must be prepared to treat fractures of the root and/or the entire tooth. One must make plans preoperatively on how such situations will be handled should they be noted intraoperatively. Surgical endodontic success rates have improved dramatically over the years with the development of newer retrofilling materials and the use of ultrasonic preparations. Previously cited success rates of 60% to 70% now have increased to more than 90% in many studies because of the routine use of ultrasonic retrograde preparation and the use of mineral trioxide aggregate as a filling material.77 This significant improvement makes apical surgery a much more predictable and valuable adjunct in the treatment of symptomatic teeth. The primary option for the treatment of symptomatic endodontically treated teeth is that of conventional retreatment versus the surgical approach. An algorithm for decision making regarding retreatment versus surgery versus extraction is presented in Figure 94-2.78 Discuss the option of conventional retreatment with patients. Clinical studies, however, have not shown retreatment to be more successful than surgery; in fact, one prospective study found surgical treatment to have a higher success rate.79 Although endodontic retreatment seems more “conservative,” the removal of posts, reinstrumentation of the tooth, and removal of tooth structure increase the chance of fracture. Surgical treatment of failures also provides the opportunity to retrieve tissue for histological examination to rule out a noninfectious cause of a lesion (Figure 94-3). However, it is accepted that re-root treatment is usually attempted before surgical endondontics is carried out in teeth without posts.80 The clinician also must discuss the option of extraction with immediate or delayed implant placement as an alternative to periapical surgery. There is no debate in dentistry that implants can outlast tooth-supported restorations. Therefore, to have data to predict the expected success of surgery so that the patient can use this information in the decision-making process is valuable. Box 94-1 notes factors that improve success. In cases of an expected poorer success rate such as the presence of severe periodontal bone loss, the decision to extract the tooth and place an implant may be a more efficacious and clinically predictable procedure.

A

B FIG 94-2  Two examples of technical factors requiring apical surgery. Although these are not common, the success rate is usually high because the canal system is likely well obturated. A, Overfill of gutta percha causing symptoms including chronic sinusitis. B, Broken endodontic instrument in the apical third with pain and drainage.

Cases that have a final prosthetic restoration already in place are usually easier to recommend for surgical intervention. If the symptoms do not resolve, the patients have expended only the additional time and expense of the surgical portion of their care, for they already have a definitive restoration. The surgeon may be called on to treat teeth that cannot be negotiated for conventional orthograde endodontics. Teeth with calcified canals may be managed appropriately with apical surgery alone with a retrograde filling if the tooth is critical to a restorative treatment plan. Danin and colleagues showed at least a 50% rate of complete radiographic healing and only one failure in 10 cases over a 1-year observation period in cases treated surgically only and without endodontic treatment.81 Bacteria still remained in the canals of the tooth in 90% of these cases, which may lead to a later failure.

Determination of “Success” of Apical Surgery More complicated decisions are involved with teeth that have not been restored definitively. In that situation, the surgeon not only has to consider the preoperative potential for the apical surgery to be successful but also often must determine when the case is deemed successful, and the patient can return to the general dentist for the final restoration. Once a final restoration is placed, considerably more time and expense has been invested and subsequent failure is more troublesome to the patient. Rud and colleagues retrospectively reviewed radiographs following apical surgery to determine radiographic signs of success.82 They noted that a tooth with radiographic evidence

CHAPTER 94  Controversies in Office-Based Surgery

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Symptomatic tooth (continued pain, sinus tract, gross pulpal involvement) No

Failed previous endodontics?

Refer for RCT

Yes

RCT successful

Yes

Final restoration

No Yes

Can tooth be retreated? No

Will patient accept retreatment?

Yes

Retreatment

No

Evidence of crack/fracture?

Yes

Extract

No

Implant/prosthesis

No No

Adequate periodontal status? (<25% vertical bone loss, pocket depth <5 mm)

Abutment for existing prosthesis?

No No

Yes

Abutments and prosthesis in good condition?

Yes

No

Adequate tooth structure for prosthesis?

Extract

Implant/prosthesis

Yes

Yes Patient able to tolerate surgery? Yes Surgical exploration Yes Fracture found?

Yes

Molar tooth No

No Limited root resection

Yes

Tooth periodontally sound

Yes

Resect root

No

Extract

Ultrasonic prep

Retrograde filling

Postoperative radiograph Tooth asymptomatic after 3 months?

No

Extract

Implant/prosthesis

Yes Periapical film No Evidence of bone fill?

Yes

Final restoration

No Repeat periapical 6 months

Evidence of bone fill?

Yes

Final restoration

FIG 94-3  Algorithm for apical surgery. RCT, Root canal therapy. (Reproduced with permission of Lieblich SE: Periapical surgery: clinical decision making. Oral Maxillofac Surg Clin North Am 14[2]:179-186, 2002.)

of bone during the first 4 years after surgery (defined as “successful” healing in their classification) was stable throughout the remainder of their study period (up to 15 years). A postoperative radiograph is usually taken on the day of the procedure, although this can be delayed to the initial review appointment within a few days of surgery. Following this, in the absence of any complications, further radiographic follow-up is indicated at 3 months. Annual clinical and radiographic review is indicated until healing has taken place demonstrating good bony in-fill.83 However, if significant bone fill has not been noted, the patient should be recalled after another 3 months for a radiographic follow-up. Any increase in the size of the

radiolucency or lack of improvement should caution the dentist and delay the final restoration. If the situation is not clear at 6 months after surgery, a temporary restoration, loaded for at least 3 months, is often a good “litmus test” of the success of the surgery and can predict whether the final restoration will last for some time. Success rates of 44% to 90% have been reported for traditional surgical endodontics. Whereas, microsurgical endodontics yielded success rates of 57% to 97%.84

The Cracked or Fractured Tooth If there is a high index of suspicion for a vertical root fracture, then one should obtain preoperative radiographs and make a

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CHAPTER 94  Controversies in Office-Based Surgery

BOX 94-1  Factors Associated With

Success and Failures in Periapical Surgery Success Preoperative Factors Dense orthograde fill Healthy periodontal status • No dehiscence • Adequate crown/root ratio Radiolucent defect isolated to apical one-third of the tooth Tooth treated • Maxillary incisor • Mesiobuccal root of maxillary molars

Postoperative Factors Radiographic evidence of bone fill following surgery Resolution of pain and symptoms Absence of sinus tract Decrease in tooth mobility

Failure Preoperative Factors Clinical or radiographic evidence of fracture Poor or lack of orthograde filling Marginal leakage of crown or post Poor preoperative periodontal condition Radiographic evidence of post perforation Tooth treated • Mandibular incisor

Postoperative Factors Lack of bone repair following surgery Lack of resolution of pain Fistula does not resolve or returns

careful clinical examination before undertaking surgery. Mandibular molars and maxillary premolars are the most frequent teeth to present with occult vertical root fractures. Although surgical exploration may be needed to show the presence of a fracture definitively (Figure 94-4), subtle radiographic signs may alert the surgeon that a fracture is present and that the surgery is unlikely to be successful. Tamse and colleagues looked at radiographs of maxillary premolars for comparison with the clinical findings at the time of surgery.85 Few (one out of 15) teeth with an isolated, well-corticated periapical lesion had a vertical root fracture. In contrast, a halo-type radiolucency almost always was associated with a vertical root fracture (Figure 94-5). This type of radiolucency also is known as a J-type where a widened periodontal ligament space connects with the periapical lesion, creating a J pattern. Review of the exploratory nature of the surgery and findings that may arise intraoperatively is critical in patient discussions. In cases of root fracture, a decision during surgery may need to be made to resect a root or extract a tooth if a fractured root is found. Obtaining the appropriate preoperative consent and determining how the extracted tooth site will be managed (with or without a temporary removeable partial denture) must be established before surgery commences.

CONCOMITANT PERIODONTAL PROCEDURES One can consider the use of guided tissue regeneration, alloplastic or allogenic bone grafting, and root planing in

A

B

FIG 94-4  A, Atypical radiolucency along the lateral aspect of the root and not truly involving the apex. B, Although correctly treated at the time of referral because of the nonresolving radiolucency with periapical surgery, the suspicious nature of the lesion warranted submission of the tissue for histological examination. Confirmation with the original treating dentist revealed that the indication for the endodontic treatment was solely the incidental finding of radiolucency and that vital pulp tissue was noted. The final pathological finding was a cystic ameloblastoma.

conjunction with periapical surgery. In cases of severe bone dehiscence, the likelihood of success is compromised substantially and may lead to the intraoperative decision to extract the tooth. Periodontal probing before surgery often detects the presence of significant bony defects. Sometimes the amount of bone loss cannot be appreciated until a flap is removed from the area. Thus one needs to stress the exploratory nature of the surgery preoperatively with the patient. The placement of an additional foreign body, such as a GORE-TEX membrane to an area already infected, is more likely to lead to failure of the surgery. Membrane stabilization and adequate mobilization of soft tissues to cover the membrane may increase the complexity of the surgical procedure. Nonresorbable membranes also require a second procedure for their removal that may be unacceptable to the patient and may increase scarring.

SURGICAL PROCEDURES Various steps are involved in the periapical surgical procedure. Initial exposure of the apical region is needed to allow access to the apex for root resection. Resect approximately 2 to 3 mm of the root apex. The root resection removes the end of the root containing the aberrant canals. Also, the farther from the coronal portion of the tooth, the less dense the endodontic filling is likely to be. Following the root resection, perform a thorough curettage of the periapical region, with care to recognize local structures such as the maxillary sinus or the inferior alveolar nerve. Curettage removes periapical debris that may have been forced out of the apex during the previous preparation of the root canal system. One may recover tissue at this time for histological examination if indicated (see the following

CHAPTER 94  Controversies in Office-Based Surgery

A

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provides rapid access to the apices of the teeth, it substantially limits the surgery to only a root resection and periapical seal. Proponents of this flap claim that it prevents recession around existing crowns, which could lead to a metal margin showing postoperatively. Place the semilunar flap entirely in the nonkeratinized or unattached gingiva. By definition, this tissue is moving constantly during normal oral function, leading to dehiscence and increased scarring. Incisions placed in unattached tissues tend to heal slower and with more discomfort. Once a semilunar incision is made, the surgeon is limited to the periapical region. If the root is noted to be fractured, extraction via this flap may lead to a severe defect. With a multirooted tooth, a root resection of one of the fractured roots may not be possible. Additionally, localized root planing or other periodontal procedures cannot be accomplished. The size of the bone defect may be greater than that anticipated based on the preoperative radiographs, and the possibility of the suture line being over the defect might cause the incision to open up and heal secondarily. Finally, many cases of periapical surgery on maxillary molars and premolars involve an opening into the sinus cavity.86 Keeping the incision as far away from the sinus opening as possible (i.e., a sulcular incision) significantly reduces the chance of an oral-antral communication.

To Take a Biopsy or Not to Take a Biopsy?

B FIG 94-5  A, Example of a periapical lesion isolated to the apical one-third of the root. These rarely are associated with a vertical root fracture. B, In contrast, this type of radiographic lesion, known as a halo or J type of radiolucency, has ill-defined cortical borders and most likely is associated with a vertical root fracture.

discussion). Then prepare a retrograde filling with the use of the ultrasonic device. This creates a micro-apical restoration that is retentive due to the parallel walls. The ultrasonic devices create a conservative preparation and often find unfilled canals or an isthmus of retained pulpal tissue connecting two canals, particularly in the mesiobuccal roots of maxillary first molars. With a retrograde filling, it is important to seal the root canal system hermetically to prevent further leakage of bacteria into the periapical tissues. Many filling materials have been used throughout the years, and many do work well. The most contemporary material, MTA (Tulsa Dentsply Endodontics, Tulsa, OK), has been shown histologically to deposit bone around it. Its handling characteristics are different from other dental materials, because it is hydrophilic and does not reach a full firm set for 2 to 4 hours. This is not clinically significant because the region is not load bearing at least for some time following the apical surgery.

Surgical Access Surgical access is a compromise between the need for visibility and the risk to adjacent structures. Many surgeons use the semilunar flap to access the periapical region. Although this flap

Substantial controversy exists as to whether all periapical lesions treated surgically should have soft tissue removed and submitted for histological evaluation. An editorial by Walton questioning the rationale of submitting all soft tissue recovered for histological examination subsequently ignited a series of letters to the editor.87 Organizations such as the American Association of Endodontists have stated in their standards that if soft tissue can be recovered from the apical surgery site, then it must be submitted for pathological evaluation. On cursory review, it seems that it is easier to make this recommendation than to have the surgeon determine whether there is anything unusual about the case that warrants histological examination. Walton makes a convincing argument against the submission of all tissues, for similar-appearing radiolucencies that are not treated surgically do not have tissue retrieved for pathological identification.87 Also accepted is that the differentiation between a periapical granuloma or periapical cyst has no direct bearing on clinical outcomes and therefore cannot be used as a rationalization for the submission of tissue. The dilemma falls back to the surgeon, and if a rare lesion should present in the context of a periapical lesion for which a biopsy is not taken in a timely manner, the surgeon may be exposed to claims of malpractice. Many surgeons have a case or two in their careers that have “surprised” them based on the final pathological diagnosis. However, careful review of these cases usually depicts a clinical situation inconsistent with a typical periapical infection (see Figure 94-3). An approach more logical than a purely defensive one is to set up guidelines for determining when tissue submission is not necessary. These guidelines are listed in Box 94-2. In each specific case, the surgeon should document in the patient record the rationale for electing not to submit tissue. At a recent meeting of the American Association of Oral and Maxillofacial Surgeons, only 8% of those attending a symposium on endodontic surgery “always” submit tissue for histological examination.88

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CHAPTER 94  Controversies in Office-Based Surgery

BOX 94-2  Indications for Non-Submission

of Periapical Soft Tissues for Histological Review

Clear evidence of pre-existing endodontic involvement of a tooth (i.e., pulpal necrosis was present, not just a periapical radiolucency) Unilocular radiolucency associated with the apical one-third of the tooth Lesion is not in association with an impacted tooth No history of malignancy that could represent spread of a metastasis Patient will return for follow-up examinations and radiographs No tissue recovered at the time of surgery

TABLE 94-1  Levels of Anesthesia Type

Description

Anxiolysis

Patients are awake and alert, and all reflexes are fully intact. Patients have a sensation of being “less anxious.” Achieved with oral sedation and/or nitrous oxide. Minimally depressed level of consciousness. Patient continually maintains his or her airway without assistance. All reflexes are intact. Patients may have amnesia about part or all of the procedure. Achieved typically with incremental doses of an intravenously administered benzodiazepine. State of depressed consciousness with probable loss at times of the protective airway reflexes. Patients initially may not respond to painful stimulation, and at least partial amnesia is expected. Achieved with intravenous and/or inhalational agents. A state of unconsciousness with a partial to complete loss of protective reflexes. Patients require assistance in ventilation and do not respond to painful stimulation. Achieved with intravenous and/or potent inhalational agents.

Conscious sedation

Deep sedation

General anesthesia

AMBULATORY ANESTHESIA The provision of ambulatory anesthesia services is considered an integral part of the practice of oral and maxillofacial surgery in the United States and Canada. Most offices are set up for the provision of anesthesia in conjunction with commonly performed procedures such as third molar extractions, implants, and other dentoalveolar surgeries. Some offices perform lengthier procedures such as genioplasty or mandibular osteotomies, but that is not as common. The level of anesthesia often is described as noted in Table 94-1. The definitions lie in a continuum and patients may move from one level to another, which occasionally may not be expected by the operator/anesthetist. Many feel that the doctor’s training should be at least one level greater than the level required in the procedure he or she is attempting. Individual patient responses to drugs vary greatly, so vigilance with observation and monitoring is vital to maintain the patient in the desired plane of anesthesia. Typically the oral and maxillofacial surgeon maintains patients under planes of deep sedation during outpatient ambulatory surgery. Incremental doses of medications using a balanced technique (benzodiazepine, opioids, and an intravenous general anesthetic) are given. The benzodiazepines have the primary role in creating anxiolysis and sedation. A secondary finding is anterograde amnesia, which many patients perceive as a positive aspect of the sedation. Benzodiazepines have

little to no effects on the cardiovascular system and have a wide therapeutic index. Although the opioids have primarily analgesic properties, they also increase the depth of the sedation, especially when used in conjunction with benzodiazepines. Propofol has replaced methohexital among many North American oral and maxillofacial surgeons because of its rapid redistribution and antiemetic properties. Although pain on injection has been reported as a significant adverse effect in the anesthesia literature, the oral surgery patient typically has received other drugs initially that obtund the pain on its injection. The potent inhalational agents, such as sevoflurane and desflurane, have some applications in the oral surgery practice, but concerns about scavenging waste gas in the nonintubated patient and potential for induction of general anesthesia limit their use. The intravenous route of administration is preferred so that drugs can be given in a small test dose to observe for an untoward response and then slowly titrated to the desired effect. Once the patient is deeply sedated, local anesthetic infiltrations and nerve blocks are given before initiation of the surgery. Drugs used have been improved over the years to reduce the risks of adverse effects and interactions with other medications that the patient may be taking. In addition, the redistribution of these medications is rapid, allowing for a faster recovery and improved time to discharge. Finally, many of the drugs have reversal agents (e.g., flumazenil for the benzodiazepines and naloxone for the narcotic medications). Thus if the patient develops a recognized respiratory depression following narcotic administration, the depression can be reversed and spontaneous respirations should return quickly. Most reversal agents do not last as long as the active drug, so careful monitoring for resedation and possible additional doses is required. The intramuscular route of administration may be used as well to induce deep sedation/general anesthesia. For the mentally handicapped or severely uncooperative patient, the intramuscular route may be the most effective way to initiate the anesthetic. This route has significant disadvantages compared with the intravascular route because drugs cannot be titrated and test doses cannot be given. The pharmacokinetics of the intramuscular route are also different, and a prolonged sedation with a delay in recovery is expected. Once a patient is sedated with the intramuscularly administered drugs, one should start an intravenous line to maintain the patient with additional medication and also give access if emergency drugs are needed. The intravenous line allows the patient to be rehydrated because there has been a preoperative period of fasting and fluid restrictions. This fluid resuscitation has been shown to reduce the incidence of postanesthetic nausea and dizziness.89 Training standards for the oral and maxillofacial surgeons are promulgated by the American Dental Association in their Standards for Advanced Specialty Education Programs in Oral and Maxillofacial Surgery; all programs must meet these standards in order to be accredited. Oral and maxillofacial residents in an American Dental Association approved program are required to perform at least 4 months on the anesthesia service, functioning at a level consistent with an anesthesia resident. This training is supplemented by hospital rotations on the medical and surgical services. Although the resident is on the oral surgery service, the American Dental Association mandates that at least 100 cases of deep sedation/general anesthesia be done by the residents yearly for each approved first-year resident position. This anesthetic experience in the oral surgery clinic is to include experiences with adult and pediatric patients.

CHAPTER 94  Controversies in Office-Based Surgery BOX 94-3  Indications for Deep Sedation

or General Anesthesia

Patient unwilling to have procedure performed solely with local anesthesia History of physical reactions of stress and anxiety (e.g., syncopal episodes and hyperventilation) Patient unable to cooperate (e.g., mentally handicapped or young age) Local anesthesia alone would be ineffective in blocking the pain of the procedure Long surgical procedure Need for full coverage of facial areas with potential for claustrophobic reaction

(From Lieblich SE: General anaesthesia for the office patient. In Fonseca RJ, editor: Oral and maxillofacial surgery, vol 1, Philadelphia, 2000, Saunders.)

Advanced cardiac life support training also is mandated during the training program for each resident. Anesthetic care administered in the Official Medical Fee Schedule office ranges from local anesthesia and nitrous oxide analgesia to conscious sedation and deep sedation/general anesthesia. Patients are screened based on the potential discomfort of the procedure and the specific concerns or anxieties of the individual. Box 94-3 lists various indications for ambulatory anesthesia. Various factors render a patient unsuitable for anesthesia in the office setting. Careful consultation and evaluation are indicated to review the patient’s overall medical condition. An airway-specific examination is also critical when evaluating the patient before the procedures. Patients with predicted difficult airways (e.g., short neck, Mallampati class III or IV, or limited range of opening) are not good candidates for an office anesthetic and should be treated with local anesthesia or local anesthesia supplemented with nitrous oxide and oxygen or should be taken to a hospital or surgical center for the anesthetic. Significant medical disorders also dictate that the patient be managed in a hospital setting, even for relatively minor oral surgical procedures. Evaluation of the patient’s medical history, including a review of systems, is necessary to assign an American Society of Anesthesiologists (ASA) risk classification. Measure blood pressure and pulse at preoperative consultation. Patients assigned to ASA I and II classifications regularly are treated in the office setting under anesthesia without additional laboratory testing. Patients with a systemic disease that is stable (e.g., well-controlled insulin-dependent diabetes mellitus) are assigned an ASA III class and can be treated following a more thorough evaluation of their health status, including possible consultation with their primary care physician. A systemspecific physical examination and laboratory testing may be indicated in this group of patients. For example, specifically ask a patient with a history of cardiac disease about his or her chest pain (stable or unstable), use of nitroglycerin, exercise tolerance, and any dyspnea. A preoperative electrocardiogram may be indicated and compared with previous studies. Patients with unstable disease (ASA class IV) are not suitable for treatment in the office setting with deep sedation/general anesthesia. Because the medical evaluation and testing may take time to complete, it is recommended that patients not be scheduled for the anesthesia on the same day as the initial consultation. Ambulatory anesthesia in the office setting is provided by an anesthetic team as described in the American Association

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of Oral and Maxillofacial Surgeons Parameters of Care.90 For deep sedation/general anesthesia procedures, the operator/ anesthetist plus at least two other trained staff members are required. One trained staff member assists with the surgical procedure, and the anesthesia assistant supports the airway and monitors the patient. Specific monitoring and anesthesia records are mandated based on the level of anesthesia administered. The anesthesia team concept has been recognized by various other organizations including the ASA in their document “ASA Guidelines for Sedation and Analgesia by Non-Anesthesiologists.”91 Monitor all patients with pulse oximetry, continuous electrocardiography, and blood pressure measurements at least every 5 minutes. Most surgeons do not use end-tidal carbon dioxide monitoring unless the patient is intubated. Establish an intravenous line, preferably before initiation of the anesthetic, and continuously administer fluids at least at a “keep-veinopen” rate. One may use other monitors such as bispectral analysis to assess the depth of the sedation.92 The surgeon determines the agents to induce and maintain anesthesia and may use many varied techniques. Typically a benzodiazepine (such as, midazolam) and a narcotic (such as, meperidine or fentanyl) are used initially. The anesthetic then is deepened before noxious periods by using a short-acting agent, such as propofol in incremental boluses. Deeper planes of anesthesia are obtained during the administration of the local anesthetic; and once achieved, the initial sedative effects of the benzodiazepine and narcotic may be sufficient. Muscle relaxants typically are not used because the goal is for the patient to maintain spontaneous respirations. Deep sedation/general anesthesia implies that the patients’ protective reflexes will be obtunded. Careful attention to the preventing fluids and foreign bodies from getting into the upper airway is vital to prevent laryngospasm or obstruction. Placement of a throat pack and vigilant suctioning of fluids is critical to prevent these events. Some surgeons elect to use the laryngeal mask airway, which may reduce the potential for tooth fragments from becoming lodged in the upper airway and cause respiratory obstruction. Such devices usually require a deeper level of anesthesia for the patient to tolerate the laryngeal mask airway without gagging. Laryngeal mask airways will not protect the lungs from the noxious effects of aspiration of gastric contents should vomiting occur. Preoperative instructions advise the patients to avoid solid foods for at least 6 hours, but they can have clear liquids until 2 to 4 hours before anesthesia induction. All patients must have an adult escort to drive them home following a monitored and supervised recovery in the office. Before discharge, the surgeon needs to verify the patient is fully awake and able to maintain his or her own airway. Vital signs such as pulse rate and blood pressure should have returned to their preoperative values. Care is necessary as the patient initially ambulates because orthostatic hypotension can occur even in younger patients. One study of patients undergoing general anesthesia for minor surgeries demonstrated orthostatic changes (lack of heart rate and diastolic pressure increases on head-up table tilt) in more than 50% of younger, healthy patients.93 Complications of anesthesia administered in the office setting are rare. Although retrospective, the incidence of brain damage or death is reported to be less than 1 in 750,000 anesthetics administered in the oral and maxillofacial surgery office.94 This contrasts with a rate of 1 in 25,000 for a conventional ambulatory surgery facility. A recent prospective

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CHAPTER 94  Controversies in Office-Based Surgery

study found no deaths in 35,000 cases performed in oral and maxillofacial surgeons’ private offices.95 Certainly, the case selection of the oral surgeon is critical in that healthier patients are selected to receive anesthetic care in the office. In addition, vigorous attention to training standards, advances in monitoring and drug safety, and reliance on the anesthetic team have maintained this enviable safety record. States and the national organizations require regular licensure and peerreviewed site visits to ensure that each practitioner maintains and follows the standards. The American Board of Oral and Maxillofacial Surgery requires diplomates to complete the office anesthesia evaluation as part of the certification maintenance program. Most complications are related to airway issues. As mentioned before, preoperative evaluation is necessary to avoid individuals with the potential to easily obstruct their airway. The oral and maxillofacial surgeon must be prepared with the necessary equipment and training to deal with a compromised airway. This may include using airway adjuncts (oral-pharyngeal airways), laryngeal mask airways, endotracheal intubation, and the creation of a surgical airway if needed in an emergency.

PITFALLS • Failure to recognize progressive periodontal involvement of erupted third molars: Research has shown that this can spread to other parts of the mouth and possibly have implications for systemic illness. • Routine use of PRP in surgical procedures given the questionable cost versus benefit, except for soft tissue healing. • Routine socket grafting following extraction, especially in the posterior part of the mouth: Although grafting in the canine and incisor region may provide some limited benefit, there is no research to suggest therapeutic advantage outside the aesthetic zone. • Indiscriminant use of xenograft material in socket grafting before implant placement: Research indicates that some materials remain for extended periods of time as nonvital (acellular) particulate matter. • Failure to recognize the radiographic and clinical signs of a root fracture can result in inappropriate therapeutic intervention. • Failure to recognize and understand a patient’s pre-existing medical diseases can put him or her at risk during ambulatory anesthesia and surgery.

ACKNOWLEDGMENTS I would like to express my gratitude to Paul M. Thomas, Stuart E. Lieblich, and Peter Ward Booth, on whose previous work this chapter is based, and to Omar Sheikh for assisting with the photographic illustrations.

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