- Email: [email protected]
Periodontal and pulpal condition of the central incisors after midline osteotomy of the maxilla
J Oral
Maxillofac
57:523-529,
Surg
1999
Periodontal and Pulpal Condition of the Central Incisors After Midline Osteotomy of the MaxiUa Arne Mordenfeld, DDS, * and Lars Andersson, DDS, PhDf Purpose: The purpose of this study was to evaluate the periodontal and pulpal condition of the central incisors after Le Fort I and midline osteotomies for transverse expansion of the maxilla. Patients and Methods: The series included 12 women and eight men, with an average age at operation of 28.4 years (range, 17 to 48 years). Each patient, examined retrospectively, underwent transverse expansion of the maxilla by combined Le Fort I and midline osteotomies. The minimum follow-up was 12 months (range, 12 to 85 months, with an average of 38 months). The central incisors were tested for percussion sound, mobility, and pulpal response to electric stimulation, and then compared with the lateral incisors. The pocket depths and the height of the alveolar bone were measured, and the root surface was evaluated for resorption on radiographs. Results: Percussion and mobility tests indicated normal values for all teeth. Four (11%) of the central incisors did not respond to electrical stimulation. There was no difference in pocket depth between the mesial and distal sulci of the central incisors. In one tooth, resorption was detectable on the medial surface of the root. Minor root surface injury was seen in two roots, although these injuries were not progressive. The alveolar bone level of the central incisors was located slightly more superiorly on the mesial than on the distal side. Conclusions: Although there may be some minor complications to the periodontal and pulpal tissues after combined Le Fort I and midline osteotomies, the harmful effects seem to be of negligible clinical significance.
because of its greater distance from the vascular supply of the palatal pedicle.ls The risk of aseptic necrosis is increased with multisegment Le Fort I osteotomies, particularly with superior repositioning or transverse expansion, which is very likely due to jeopardizing the vascular ~upply.‘~ The risk of iatrogenic periodontal defects must always be considered before performing interdental osteotomies when there is limited space between the adjacent teeth. *,14,16The most common complication reported by Steinhauser’ was loss of teeth adjacent to the midline osteotomy caused by damage to the periodontal ligament. There have been several studies evaluating the pulpal conditions after interdental osteotomies; however, in most cases the pulpal conditions were evaluated by pulp sensibility testing only.lS There are few studies regarding the effects on the periodontium and crestal height in the oral and maxillofacial surgery literature.13J4 To our knowledge, there are no studies that have evaluated both the pulpal and periodontal condition of the adjacent teeth after midline osteotomies. Thus, the purpose of this investigation was to evaluate the pulpal and periodontal conditions of the central incisors after Le Fort I osteotomy and transverse expansion of the maxilla.
The treatment of transverse deformities of the maxilla is a routine procedure in orthognathic surgery. Lateral expansion of the maxilla after Le Fort I osteotomy and sagittal osteotomy has been studied extensively.1-5 A number of different complications in the neighboring dental tissues, such as injuries to the p~lp,~l* periodontal tissue,1°J3J4 and dental roots,*J5J6 have been reported in association with segmental osteotomies. The long-term prognosis of these teeth is greatly dependent on the pulpal and periodontal status. Loss of tooth vitality is one of the most sensitive indications of early aseptic necrosis” following maxillary osteotomies, especially in the anterior region,
*Formerly, Resident, Department gery, Central Hospital, Department
of Oral and Maxillofacial
Vasteras, Sweden; Currently,
of Oral and Maxillofacial
Sur-
Consultant,
Surgery, County Hospital,
Giivle, Sweden. tchairman Maxillofacial
and Associate Professor,
Address correspondence Department
Department
of Oral and
Surgery, Central Hospital, Vaster&, Sweden. and reprint requests to Dr Andersson:
of Oral and Maxillofacial
Surgery, Central Hospital,
S72189 Vksterk, Sweden; e-mail: [email protected] o 1999Amwcan
Association
oFOral
and Maxillofacial
Surgeons
0278.2391/99/57050006$3.00/0
523
524
Patients
MIDLINE
and Methods
The pulpal and periodontal status of 40 central incisors was evaluated in 20 patients, 12 women and 8 men, who underwent transverse expansion of the maxilla in the Department of Oral and Maxillofacial Surgery, Central Hospital, Vaster&, Sweden, from 1989 to 1994. The average age at operation was 28.4 years (range, 17 to 48 years). SURGICAL TECHNIQUE The surgical procedure used to expand the maxilla was performed according to the method described by Krekmanov and Kahnberg. Le Fort I osteotomy was performed, and the maxilla downfractured and then mobilized. A midline osteotomy was performed with a reciprocating saw from the posterior nasal spine anteriorly to about 10 mm from the alveolar crest between the central incisors. The osteotomy was then completed with a thin osteotome. Parallel to the midline osteotomy, two or three additional osteotomies were performed on each side, joining the midline osteotomy just posterior to the alveolar area (Fig 1). The maxilla was expanded by pressing the nasal floor inferiorly, without the need of subperiosteal dissection of the palatal mucosa. A stainless steel palatal frame was applied to keep the maxilla in the
OS’I’EOTOMY
AND DENTAL
COMPLICATIONS
predicted transverse position. The frame was designed not to be in contact with the mucosa so as not to jeopardize the vascular supply from the greater palatine artery. The maxilla was stabilized with four miniplates. Periodontal and pulpal conditions were tested at a minimum of 12 months after surgery (range, 12 to 85 months). The following methods were applied: Tooth Percussion Sound Test This examination was performed by tapping the central incisor vertically as well as horizontally with the handle of a probe. Dull (recorded as 0) and sharp (recorded as 1) sounds, indicating normal and ankylotic conditions, respectively, were recorded.*O The lateral incisors served as controls. Tooth Mobility Measurements Mobility was tested by moving the central incisor in a labiolingual direction. The horizontal movement was measured with a slide caliper at the incisal edge relative to the adjacent tooth. The measurements were grouped as 0 = no movement; 1 = 0.2 to 1.0 mm horizontal mobility; 2 = greater than 1.O mm horizontal mobility. The lateral incisors served as controls. Pulp Sensibility A Vitality Scanner, model 2006 (Analytic Technology, Redmond, WA), was used to test the pulpal response to electrical stimulation. The probe was placed on the incisal edge, and a negative or positive response was recorded. The lateral incisors served as controls. Pocket Depth Pocket depth was measured in millimeters in the mesial and distal sulci of the central incisors with a standardized measuring pressure of 200 N/cm2 using a Vivacare TPS periodontal Probe (Vivadent, Schaan, Liechtenstein). The distal sulci served as controls. Intraoral radiographs were taken in four projections: orthoradial; mesial eccentric, 5 degrees; distal eccentric, 5 degrees; and overaxial, 5 degrees to the central incisors. An Eggen film positioner was used.*l Alveolar Bone Level The height of the alveolar bone was measured in millimeters from the cementoenamel junction on the radiographs mesial and distal to the central incisors (Fig 2). The distal sites served as controls.
FIGURE 1. Schematic view showing the various types of parallel osteotomies performed an each side to ioin the midline osteotomy just posterior to the alveolar ridge.
Root Resorption, Root Injury Findings of root resorption on radiographic evaluation were divided into three groups: 0 = no sign of resorption, normal periodontal space; 1 = root resorption penetrating less than half the distance between the root surface and the pulp; and 2 = root resorption penetrating more than half the distance between the root surface and the pulp. Root injury caused by
MORDENFELD
525
AND ANDERSSON
sulci of the central incisors was 2.2 mm and 2.1 mm, respectively. No significant differences were found (P > .05, Table 1). The mean marginal bone levels were 3.1 mm mesial and 2.7 mm distal to the central incisors, a difference that reached statistical significance (P < .05, Table 1). There were no significant differences in pocket depths and marginal bone levels between patients younger than 25 years (n = 10) and those older than 25 years (n = 10, P > .05). Moreover, there were no significant differences in pocket depths and marginal bone levels between patients with a follow-up of less than 30 months (n = 11) and those with a follow-up of 30 months or longer (n = 9,
P > .05>. Thirty-eight (92.5%) of the 40 central incisors did not show any root injuries. Two (5%) central incisors showed small root injuries in the apical third, probably caused by the saw (Figs 3 A,B). One (2.5%) tooth showed a small area of root resorption apically (Fig 4). None of the teeth with root injuries and root resorption showed any other periodontal abnormalities on the radiographs, and all of the teeth responded to electrical stimulation. The four central incisors that did not respond to electric stimulation were normal according to radiographic and clinical examination. FIGURE 2. The height of the alveolar bone [superior arrow) was measured from the cementoenamel junctlon (inferior arrow] on the radiographs
surgery, as seen on the radiographs, corded.
was also re-
STATISTICALANALYSIS Student’s t-test was used to evaluate the parametric statistics, and the chi-square test was used for the nonparametric statistics. The statistical significance was defined at P < .05.
Results The 32 incisors, which were tested in 16 of the patients, had a normal, dull, tooth percussion sound and normal tooth mobility (0.2 to 1 mm). Four patients had lingual retainers on the upper incisors and canines, and, consequently, percussion sound and mobility were not possible to test in these patients. Thirty-three (89%) of the 37 tested central incisors showed a positive reaction to electrical stimulation. Three of the central incisors and two of the lateral incisors had been endodontically treated preoperatively and could not be tested. All the other lateral incisors responded to electrical stimulation. There were no significant differences between the central and lateral incisors (P > .05). The mean pocket depth in the mesial and distal
Discussion This study shows that surgical expansion after Le Fort 1 osteotomy is a safe method, without progressive periodontal and pulpal complications. When performing a Le Fort I osteotomy, the sensory nerve fibers are severed.i7J2 However, the vascular supply is usually sufficient because of the network of venous vessels supporting the pulp. Furthermore, it has been shown that most of the teeth regain their positive response within 12 months8J1J9 Consequently, it was decided to use a follow-up time of at least 12 months postoperatively. The electric pulp tester was used only to determine sensibility or nonsensibility, and no attempt was made to quantitate the response at any particular digital
Right Central Incisor (11) Pocket depth (mm) Mesial Distal Alveolar bone level (mm) Mesial Distal
Left Central Incisor (2 1)
2.3 2.1
2 0.7 i: 0.6
2.1 2.2
3.1 2.6
-c 1.0’; i 0.6
2.8
“Denotes significant findings (P < .05).
-t 0.8 I: 0.7
3.1 + 1.1:” t 0.9
MIDLINE
FIGURE
3.
A, B Central
incisors showed
small root iniuries in the apical
reading. Electrical pulp testing cannot be used as the only criterion for pulp necrosis,19 and, therefore, was supplemented with dental radiographs and clinical evaluation. Percussion sound and tooth mobility were tested because they are important parameters in the diagnosis of ankylosis,20 periodontal disease, and hypermobility.23 In the current study, a surgical procedure was used in which several osteotomized bone segments were attached to the palatal periosteum, and the concavity of the palate was changed without stretching the mucosa.5 An unstretched soft tissue is probably less prone to compromised healing than a stretched soft tissue. A single midline palatal bone cut requires detachment of the palatal soft tissues from the bone when using a buccal approach.5J7 The stripping and the subsequent stretching of the soft palatal tissues may interfere with the vascular supply and potentially can cause aseptic necrosis. Because no preoperative examination was performed, only those results that diverged from the normal could have been present before surgery and explained by other factors. When performing interdental osteotomies, there is
OSTEOTOMY
third [mows),
AND DENTAL
which were probably
COMPLICATIONS
caused by the saw.
always a risk of direct or indirect damage to dental roots or the periodontal ligament. Direct trauma to dental hard tissue is always caused by the cutting instrument and is easily detected in radiographs as a straight line on the root surface. Indirect trauma is often caused by damage to the pulpal blood supply or by infection and is seen in radiographs as an irregular line on the root surface. In addition, root resorption may be a result of orthodontic treatment.** In the current study, there was one tooth with root resorption. This was located in the apical part of the root, penetrating less than half the distance between the surface and the pulp; the resorption was neither symptomatic nor progressive in nature. It may even have been the result of preoperative or postoperative orthodontics. These factors indicate that even if surgery is the cause of root resorption, it is not necessarily of clinical significance, and further treatment is not required. Tooth sensibility after orthognatic surgery has been reported in a number of studies.G11,19,25-27 Several of these have involved Le Fort I osteotomies without sagittal osteotomies. In 14 to 18 months after such a
MORDENFELD
527
AND ANDERSON
FIGURE 4. Tooth showing
small apical
root resorption
[arrow]
procedure, the teeth of the maxilla seem to regain their sensibility in 50% to 100% of the cases. Recently, Shehab Al-Din et a126assessed 119 teeth in 20 patients for dental nerve disturbance after Le Fort osteotomy without sagittal osteotomy by means of an electric pulp tester. After 6 months, 78% of the teeth responded positively. Kahnberg and Engstriimz7 examined tooth sensibility to electrical stimulation in 44 patients after one-segment Le Fort I osteotomy. Thirty of the examined teeth were central and lateral incisors. At the l&month follow-up, 100% of the incisors (n = 20) had regained pulp sensibility. Our results are in accordance with the previously mentioned findings. However, in a study of 27 cases, Tajima’ reported that the central and lateral incisors showed the poorest recovery after Le Fort-type osteotomies and Le Fort-type fractures, with only 23% and 50% recovery, respectively, 14 months postsurgery. Some of the patients had a sagittal osteotomy or a fracture, which prompted Tajima to speculate that the vertical bone cut may have influenced recovery of the pulpal responses, but it is the direct trauma to the
incisors that may have played the most significant role. The pulpal condition of teeth adjacent to maxillary interdental osteotomies has been surveyed by a number of authors. Johnson and Hind& examined the vitality of teeth in 17 patients who underwent subapical osteotomies. Thirty-five (21%) of 169 teeth did not respond to electrical or thermal stimulation; 25 of these were adjacent to an osteotomy site. Only four teeth were radiographically or clinically abnormal, and all of these were obviously injured during surgery. Hutchinson and MacGregor8 also studied tooth survival after subapical osteotomies. Forty-nine (91%) of 58 teeth in the mobilized segment responded to electrical stimulation 6 months after surgery in a subapical anterior maxillary group. However, not one of the transposed teeth was lost in the postoperative follow-up. Pepersack9 investigated tooth vitality after alveolar segmental osteotomy. In the study, 89 teeth were in the mobilized maxillary fragment adjacent to a vertical osteotomy without extraction or adjacent to a supplementary midline osteotomy. Eighty-two (92%) teeth reacted positively to cold stimulation 12 months postoperatively. Pepersack’s conclusions confirm that the largest number of nonreacting teeth are found in the mobilized fragment and adjacent to the vertical osteotomy when no extraction is conducted in the osteotomy site. After performing anterior segmental osteotomies, Theisen and Guernsey’ 1 surveyed 1 I6 teeth in 16 patients, of which 72 were in maxillary segments. They confirmed the risk categories, with a lower percentage of positive responses for the teeth in the mobilized segment adjacent to the osteotomy. Vedtofte and Nattestadlg reported 51 patients who had Le Fort I osteotomy performed. Of 617 teeth tested for pulpal sensibility, 38 were central incisors adjacent to interdental osteotomies. Two (5%) of these teeth failed to respond to electrical stimulation. After Le Fort I osteotomy without an interdental osteotomy, all of the central incisors regained normal sensibility reaction. All the previously cited studies on vertical osteotomies indicate that the teeth adjacent to the osteotomy are those with the highest risk for damage to the pulpal sensibility, whereas those teeth in the mobilized segment not adjacent to the osteotomy are the least involved. In the current study, four (11%) of the central incisors adjacent to the vertical osteotomy were nonresponsive, in comparison with the lateral incisors not adjacent to the osteotomy cut that all responded to electrical stimulation. Although the difference is not statistically reliable, these results are consistent with the studies mentioned previously. However, all the nonresponsive teeth did not show any other pathological signs and did not require further treat-
528 ment. Nevertheless, these teeth should be observed regularly for radiographic or symptomatic changes. The difference in alveolar bone level between the mesial and distal aspect of the central incisors and some of the sites adjacent to the midline osteotomy suggests that this is a postsurgical effect (Table 1). Future prospective studies are needed to further evaluate the alveolar bone level after midline osteotomies. Few studies in the oral and maxillofacial surgery literature have evaluated the periodontal status following interdental osteotomies. Carroll et al13investigated the effect of maxillary osteotomies on the periodontium in surgical and nonsurgical orthodontic patients. The surgery group was divided into patients having had nonsegmental maxillary osteotomies, two-piece maxillary osteotomies, and three-piece maxillary osteotomies. The two-piece subgroup had osteotomies performed between the central incisors. The investigators reported that tooth mobility was low in all groups and no significant differences were found. No differences in probing depth from that in the nonsegmental counterparts were noted at the sites of osteotomies made between the central incisors. These results are in accord with the current findings. Also in the Carroll et al study,‘3 there were no differences in attachment level when the osteotomies were made between the central incisors and in the nonsegmetalized counterparts. The attachment levels were calculated by adding gingival recession (measurement apical to the cementoenamel junction) and probing depths; no radiographs were used. The alveolar bone level in our study was measured from the cementoenamel junction on the radiographs and, therefore, these results are not comparable. We found a statistically significant loss of marginal bone. However, the magnitude of the marginal loss (0.4 mm) was not clinically meaningful and therefore should not intimidate the surgeon against performing midline osteotomies. No patient in our study required further periodontal treatment after the minimal loss of bone following surgery. Dorfman and Turvey’* evaluated osseous crestal changes after maxillary and mandibular segmental osteotomies in 10 patients. They concluded that adequate working width for the osteotomy is 3 mm or more. In the surgical method described in this article, all interdental osteotomies were performed without tooth extraction. It is important to stress that the osteotomy was performed with a thin osteotome for the last 10 mm from the alveolar crest. This procedure might have caused minimal damage to the marginal periodontal tissue. Diiker and Schillil” analyzed periodontal damage due to osteotomy in the alveolar process in beagle dogs. They found that superficial osteotomies that extended to the periodontal ligament, but did not
MIDLINE OSTEOTOMY AND DENTAL COMPLICATIONS involve the hard tissues, healed completely without discernible damage to the periodontium. When the damage extended into the cementum and dentin, partial healing occurred, with functionally favorable results. If the osteotomy entered the pulp, formation of secondary dentin occurred. Optimal healing appeared to be take place in the middle and apical thirds of the root after the resumption of normal function. These conclusions are in agreement with our findings concerning the two teeth that showed small injuries in the apical third caused by the cutting instrument.
References
5. 6. 7. 8. 9. 10.
11. 12. 13. 14. 15. 16.
17. 18.
19. 20. 21. 22.
SteinhauserEW: Midline splitting of the maxilla for correction of malocclusion. J Oral Surg 30:413, 1972 West RA, Epker BN: Posterior maxillary surgery: Its place in the treatment of dentofacial deformities. J Oral Surg 30:562, 1972 Bell WH, Epker BN: Surgical-orthodontic expansion of the maxilla.&nJOrthod70:517,1976 Krekmanov L, Lilja J, Ringqvist M: Maxillary osteotomy without the use of postoperative intermaxillary fixation: A clinical and cephalometric study. Stand J Plast Reconstr Surg 23:125, 1989 Krekmanov L, Kahnberg K-E: Transverse surgical correction of the maxilla. J Craniomaxillofac Surg l&332, 1990 JohnsonJV, Hinds EC: Evaluation of teeth vitality after subapical osteotomy. J Oral Surg 27:256, 1969 Tajima S: A longitudinal study on electric pulp testing following Le Fort type osteotomy and Le Fort type fracture. J Maxillofac Surg 3~74, 1975 Hutchinson D, MacGregor AJ: Tooth survival following various methods of sub-apical osteotomy. Int J Oral Surg 1:81, 1972 Pepersack WJ: Tooth vitality after alveolar segmental osteotomy. J Maxillofac Surg 1:85, 1973 Leibold DG, Tilson HB, Rask KR: A subjective evaluation of the re-establishment of the neurovascular supply of teeth involved in anterior maxillary osteotomy procedures. Oral Surg 32:531, 1971 Theisen FC, Guernsey LH: Postoperative sequelae after anterior segmental osteotomies. Oral Surg 41:139, 1976 Summers L, Booth DR: The early effects of segmental surgery on the human pulp. Int J Oral Surg 4:236, 1975 Carroll WJ, Haug RH, Bissada NF, et al: The effects of the Le Fort I osteotomy on the periodontium. J Oral Maxillofac Surg 50:128, 1992 Dorfman HS, Turvey TA: Alteration in osseous crestal height following interdental osteotomies. Oral Surg 48:120, 1979 Ware WH, Ashamalla M: Pulpal response following anterior maxillary osteotomy. Am J Orthod 60: 156, 1971 Diiker J, Schilli W: Rapid orthodontics after subtotal osteotomy: Biologic foundation and clinical implications, in Bell WH (ed): Surgical Correction of Dentofacial Deformities-New Concepts. Philadelphia, PA, Saunders, 1985, pp 465-489 Lanigan DT, Hey JH, West RA: Aseptic necrosis following maxillary osteotomies: Report of 36 cases. J Oral Maxillofac Surg 48:142, 1990 Geylikman YB, &tun J, Leroux BG, et al: Effects of Le Fort I osteotomy on human gingival and pulpal circulation. Int J Oral Maxillofac Surg 24:255, 1995 Vedtofte P, Nattestad A: Pulp sensibility and pulp necrosis after Le Fort I osteotomy. J Craniomaxillofac Surg 17: 167, 1989 Andersson L, BlomlGf 1, Lindskog S, et al: Tooth ankylosis: Clinical, radiographic and histological assessments. Int J Oral Surg 13:423, 1984 Eggen S: Simplification and standardization of intra-oral radiography. Quintessence Int 1:93, 1970 de Jongh M, Barnard D: Sensory nerve morbidity following Le Fort I osteotomy. J Maxillofac Surg 14:10, 1986
529
JEROLD S. GOLDBERG 23. Lindhe J: Textbook Clinical Periodonthology (ed 2). Copenhagen, Denmark, Munksgaard, 1989, p 317 24. Popp TW, Artun J, Linge L: Pulpal response to orthodontic tooth movements in adolescents: A radiographic study. Am J Orthod Dentofac Orthop 101:228, 1992 25. Ramsay DS, Artun J, Bloomquist D: Orthognathic surgery and pulpal blood flow. J Oral Maxillofac Surg 49:564, 1991
J Oral Maxiliofac
57529-530,
26. Shehab Al-Din OF, Coghlan KM, Magemris P: Sensory nerve disturbance following Le Fort I osteotomy. Int J Oral Maxillofac Surg 25:13, 1996 27. Kahnberg K-E, Engstrijm H: Recovery of maxillary sinus and tooth sensibility after Le Fort I osteotomy. Br J Oral Maxlllofac Surg 25:68, 1987
Surg
1999
Discussion Periodontal and Pulpal Condition of the Central Incisors After Midline Osteotomy of the Maxilla Jet-old S. Goldberg, DDS Dean, School of Dentistry, Professor of Oral & Maxillofacial Surgery, Case Western Reserve University( Cleveland, Ohio; e-mail: [email protected]
This article, which looks at periodontal and pulpal health after a segmental, midline osteotomy, is one of several publications on this or related subjects that are referenced by the authors. The various articles tend to use different parameters of pulpal or gingival health and often measures of those parameters are carried out in different ways or with different devices. It is unfortunate that none of the published research is an attempt to reproduce a previously done experiment at a different center. Be that as it may, this study successfully supports the notion that segmental osteotomies that are performed concomitantly with Le Fort I osteotomies rarely have clinically significant detrimental effects on either the pulpal or periodontal tissues. These positive results are true throughout the dental arch as well as specifically at the interdental osteotomy site. Concerning root resorption, it would have been helpful for this study to have a control group of orthodontically treated patients who did not have surgery with which to compare results. The article by Carroll et al, cited in this article, is an example of a similar report that falls short of presenting data that is reproducible.’ It investigated the parameters of plaque index, gingival index, tooth mobility, width of keratinized tissue, probing depth, and gingival recession. The experimental group had segmental orthognathic surgery and was compared with a control group of patients who had orthodontic treatment without surgery. This investigation looked at patients having osteotomies between the premolars and canines as well as between the central incisors. The only statistically significant findings were in the probing depths of the teeth adjacent to the osteotomies between the canines and the premolars and in the width of the keratinized tissue. However, no probing depths at the osteotomy sites exceeded 3 mm so that the statistically significant finding is of no clinical concern. The greater width of attached gingiva in the experimental group is probably related to the high incidence of vertical maxillary excess in the experimental population.
In addition to the main topic of this article, the authors support a technique using multiple palatal osteotomies to depress and widen the maxillary vault. In the original article, by Krekmanov and Kahnberg, describing this technique there is little to support its use over one or two parasagittal osteotomies.2 Krekmanov and Kahnberg reported horizontal relapse and soft tissue lacerations. It would be interesting to know what additional information there is to support this approach. The concept is interesting, but I do not know if the additional osteotomies really make a difference. The authors also describe using a chisel in the midline to complete the bone cut between the central incisors for a distance of 10 mm above the crest of the interdental ridge. In most cases, there is some indication of a suture line between the centrals. Placing a chisel in this line (or where you would imagine this line to be, if it does not exist) and carrying the osteotomy above the level of the teeth is both safe and easy. This should reduce the chance of direct injury to teeth about which the authors’ expressed concern. In reviewing the literature, it appears that earlier reports (in the 1970s) indicate a higher incidence of pulpal and periodontal complications than more recent investigations. Perhaps we have identified approaches that diminish the incidence of these complications. Using a flexible chisel for interdental osteotomies, requiring that there is adequate space between tooth roots before surgery, being careful not to damage the palatal soft tissue, designing splints that do not impinge on soft tissue, performing model surgery that depicts reasonable movement of segments, and planning procedures that do not exceed the physiologic or mechanical limits of the tissues are all things that may reduce the incidence of pulpal and periodontal complications. It is true that even with good planning and careful execution, vascular compromise may occur. However, it is infrequent that major vascular compromise leads to the loss of teeth or supporting bone. This and other articles show that it is also infrequent that more subtle complications, such as loss of alveolar crest, pulpal degeneration, or loss of the level of gingival attachment are a problem. One can express concern about the parameters that were chosen or the methods of measurement or about the existence or appropriateness of the controls but, at this point, it is reasonable to say that midline osteotomies performed con-
Maxillofac
57:523-529,
Surg
1999
Periodontal and Pulpal Condition of the Central Incisors After Midline Osteotomy of the MaxiUa Arne Mordenfeld, DDS, * and Lars Andersson, DDS, PhDf Purpose: The purpose of this study was to evaluate the periodontal and pulpal condition of the central incisors after Le Fort I and midline osteotomies for transverse expansion of the maxilla. Patients and Methods: The series included 12 women and eight men, with an average age at operation of 28.4 years (range, 17 to 48 years). Each patient, examined retrospectively, underwent transverse expansion of the maxilla by combined Le Fort I and midline osteotomies. The minimum follow-up was 12 months (range, 12 to 85 months, with an average of 38 months). The central incisors were tested for percussion sound, mobility, and pulpal response to electric stimulation, and then compared with the lateral incisors. The pocket depths and the height of the alveolar bone were measured, and the root surface was evaluated for resorption on radiographs. Results: Percussion and mobility tests indicated normal values for all teeth. Four (11%) of the central incisors did not respond to electrical stimulation. There was no difference in pocket depth between the mesial and distal sulci of the central incisors. In one tooth, resorption was detectable on the medial surface of the root. Minor root surface injury was seen in two roots, although these injuries were not progressive. The alveolar bone level of the central incisors was located slightly more superiorly on the mesial than on the distal side. Conclusions: Although there may be some minor complications to the periodontal and pulpal tissues after combined Le Fort I and midline osteotomies, the harmful effects seem to be of negligible clinical significance.
because of its greater distance from the vascular supply of the palatal pedicle.ls The risk of aseptic necrosis is increased with multisegment Le Fort I osteotomies, particularly with superior repositioning or transverse expansion, which is very likely due to jeopardizing the vascular ~upply.‘~ The risk of iatrogenic periodontal defects must always be considered before performing interdental osteotomies when there is limited space between the adjacent teeth. *,14,16The most common complication reported by Steinhauser’ was loss of teeth adjacent to the midline osteotomy caused by damage to the periodontal ligament. There have been several studies evaluating the pulpal conditions after interdental osteotomies; however, in most cases the pulpal conditions were evaluated by pulp sensibility testing only.lS There are few studies regarding the effects on the periodontium and crestal height in the oral and maxillofacial surgery literature.13J4 To our knowledge, there are no studies that have evaluated both the pulpal and periodontal condition of the adjacent teeth after midline osteotomies. Thus, the purpose of this investigation was to evaluate the pulpal and periodontal conditions of the central incisors after Le Fort I osteotomy and transverse expansion of the maxilla.
The treatment of transverse deformities of the maxilla is a routine procedure in orthognathic surgery. Lateral expansion of the maxilla after Le Fort I osteotomy and sagittal osteotomy has been studied extensively.1-5 A number of different complications in the neighboring dental tissues, such as injuries to the p~lp,~l* periodontal tissue,1°J3J4 and dental roots,*J5J6 have been reported in association with segmental osteotomies. The long-term prognosis of these teeth is greatly dependent on the pulpal and periodontal status. Loss of tooth vitality is one of the most sensitive indications of early aseptic necrosis” following maxillary osteotomies, especially in the anterior region,
*Formerly, Resident, Department gery, Central Hospital, Department
of Oral and Maxillofacial
Vasteras, Sweden; Currently,
of Oral and Maxillofacial
Sur-
Consultant,
Surgery, County Hospital,
Giivle, Sweden. tchairman Maxillofacial
and Associate Professor,
Address correspondence Department
Department
of Oral and
Surgery, Central Hospital, Vaster&, Sweden. and reprint requests to Dr Andersson:
of Oral and Maxillofacial
Surgery, Central Hospital,
S72189 Vksterk, Sweden; e-mail: [email protected] o 1999Amwcan
Association
oFOral
and Maxillofacial
Surgeons
0278.2391/99/57050006$3.00/0
523
524
Patients
MIDLINE
and Methods
The pulpal and periodontal status of 40 central incisors was evaluated in 20 patients, 12 women and 8 men, who underwent transverse expansion of the maxilla in the Department of Oral and Maxillofacial Surgery, Central Hospital, Vaster&, Sweden, from 1989 to 1994. The average age at operation was 28.4 years (range, 17 to 48 years). SURGICAL TECHNIQUE The surgical procedure used to expand the maxilla was performed according to the method described by Krekmanov and Kahnberg. Le Fort I osteotomy was performed, and the maxilla downfractured and then mobilized. A midline osteotomy was performed with a reciprocating saw from the posterior nasal spine anteriorly to about 10 mm from the alveolar crest between the central incisors. The osteotomy was then completed with a thin osteotome. Parallel to the midline osteotomy, two or three additional osteotomies were performed on each side, joining the midline osteotomy just posterior to the alveolar area (Fig 1). The maxilla was expanded by pressing the nasal floor inferiorly, without the need of subperiosteal dissection of the palatal mucosa. A stainless steel palatal frame was applied to keep the maxilla in the
OS’I’EOTOMY
AND DENTAL
COMPLICATIONS
predicted transverse position. The frame was designed not to be in contact with the mucosa so as not to jeopardize the vascular supply from the greater palatine artery. The maxilla was stabilized with four miniplates. Periodontal and pulpal conditions were tested at a minimum of 12 months after surgery (range, 12 to 85 months). The following methods were applied: Tooth Percussion Sound Test This examination was performed by tapping the central incisor vertically as well as horizontally with the handle of a probe. Dull (recorded as 0) and sharp (recorded as 1) sounds, indicating normal and ankylotic conditions, respectively, were recorded.*O The lateral incisors served as controls. Tooth Mobility Measurements Mobility was tested by moving the central incisor in a labiolingual direction. The horizontal movement was measured with a slide caliper at the incisal edge relative to the adjacent tooth. The measurements were grouped as 0 = no movement; 1 = 0.2 to 1.0 mm horizontal mobility; 2 = greater than 1.O mm horizontal mobility. The lateral incisors served as controls. Pulp Sensibility A Vitality Scanner, model 2006 (Analytic Technology, Redmond, WA), was used to test the pulpal response to electrical stimulation. The probe was placed on the incisal edge, and a negative or positive response was recorded. The lateral incisors served as controls. Pocket Depth Pocket depth was measured in millimeters in the mesial and distal sulci of the central incisors with a standardized measuring pressure of 200 N/cm2 using a Vivacare TPS periodontal Probe (Vivadent, Schaan, Liechtenstein). The distal sulci served as controls. Intraoral radiographs were taken in four projections: orthoradial; mesial eccentric, 5 degrees; distal eccentric, 5 degrees; and overaxial, 5 degrees to the central incisors. An Eggen film positioner was used.*l Alveolar Bone Level The height of the alveolar bone was measured in millimeters from the cementoenamel junction on the radiographs mesial and distal to the central incisors (Fig 2). The distal sites served as controls.
FIGURE 1. Schematic view showing the various types of parallel osteotomies performed an each side to ioin the midline osteotomy just posterior to the alveolar ridge.
Root Resorption, Root Injury Findings of root resorption on radiographic evaluation were divided into three groups: 0 = no sign of resorption, normal periodontal space; 1 = root resorption penetrating less than half the distance between the root surface and the pulp; and 2 = root resorption penetrating more than half the distance between the root surface and the pulp. Root injury caused by
MORDENFELD
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AND ANDERSSON
sulci of the central incisors was 2.2 mm and 2.1 mm, respectively. No significant differences were found (P > .05, Table 1). The mean marginal bone levels were 3.1 mm mesial and 2.7 mm distal to the central incisors, a difference that reached statistical significance (P < .05, Table 1). There were no significant differences in pocket depths and marginal bone levels between patients younger than 25 years (n = 10) and those older than 25 years (n = 10, P > .05). Moreover, there were no significant differences in pocket depths and marginal bone levels between patients with a follow-up of less than 30 months (n = 11) and those with a follow-up of 30 months or longer (n = 9,
P > .05>. Thirty-eight (92.5%) of the 40 central incisors did not show any root injuries. Two (5%) central incisors showed small root injuries in the apical third, probably caused by the saw (Figs 3 A,B). One (2.5%) tooth showed a small area of root resorption apically (Fig 4). None of the teeth with root injuries and root resorption showed any other periodontal abnormalities on the radiographs, and all of the teeth responded to electrical stimulation. The four central incisors that did not respond to electric stimulation were normal according to radiographic and clinical examination. FIGURE 2. The height of the alveolar bone [superior arrow) was measured from the cementoenamel junctlon (inferior arrow] on the radiographs
surgery, as seen on the radiographs, corded.
was also re-
STATISTICALANALYSIS Student’s t-test was used to evaluate the parametric statistics, and the chi-square test was used for the nonparametric statistics. The statistical significance was defined at P < .05.
Results The 32 incisors, which were tested in 16 of the patients, had a normal, dull, tooth percussion sound and normal tooth mobility (0.2 to 1 mm). Four patients had lingual retainers on the upper incisors and canines, and, consequently, percussion sound and mobility were not possible to test in these patients. Thirty-three (89%) of the 37 tested central incisors showed a positive reaction to electrical stimulation. Three of the central incisors and two of the lateral incisors had been endodontically treated preoperatively and could not be tested. All the other lateral incisors responded to electrical stimulation. There were no significant differences between the central and lateral incisors (P > .05). The mean pocket depth in the mesial and distal
Discussion This study shows that surgical expansion after Le Fort 1 osteotomy is a safe method, without progressive periodontal and pulpal complications. When performing a Le Fort I osteotomy, the sensory nerve fibers are severed.i7J2 However, the vascular supply is usually sufficient because of the network of venous vessels supporting the pulp. Furthermore, it has been shown that most of the teeth regain their positive response within 12 months8J1J9 Consequently, it was decided to use a follow-up time of at least 12 months postoperatively. The electric pulp tester was used only to determine sensibility or nonsensibility, and no attempt was made to quantitate the response at any particular digital
Right Central Incisor (11) Pocket depth (mm) Mesial Distal Alveolar bone level (mm) Mesial Distal
Left Central Incisor (2 1)
2.3 2.1
2 0.7 i: 0.6
2.1 2.2
3.1 2.6
-c 1.0’; i 0.6
2.8
“Denotes significant findings (P < .05).
-t 0.8 I: 0.7
3.1 + 1.1:” t 0.9
MIDLINE
FIGURE
3.
A, B Central
incisors showed
small root iniuries in the apical
reading. Electrical pulp testing cannot be used as the only criterion for pulp necrosis,19 and, therefore, was supplemented with dental radiographs and clinical evaluation. Percussion sound and tooth mobility were tested because they are important parameters in the diagnosis of ankylosis,20 periodontal disease, and hypermobility.23 In the current study, a surgical procedure was used in which several osteotomized bone segments were attached to the palatal periosteum, and the concavity of the palate was changed without stretching the mucosa.5 An unstretched soft tissue is probably less prone to compromised healing than a stretched soft tissue. A single midline palatal bone cut requires detachment of the palatal soft tissues from the bone when using a buccal approach.5J7 The stripping and the subsequent stretching of the soft palatal tissues may interfere with the vascular supply and potentially can cause aseptic necrosis. Because no preoperative examination was performed, only those results that diverged from the normal could have been present before surgery and explained by other factors. When performing interdental osteotomies, there is
OSTEOTOMY
third [mows),
AND DENTAL
which were probably
COMPLICATIONS
caused by the saw.
always a risk of direct or indirect damage to dental roots or the periodontal ligament. Direct trauma to dental hard tissue is always caused by the cutting instrument and is easily detected in radiographs as a straight line on the root surface. Indirect trauma is often caused by damage to the pulpal blood supply or by infection and is seen in radiographs as an irregular line on the root surface. In addition, root resorption may be a result of orthodontic treatment.** In the current study, there was one tooth with root resorption. This was located in the apical part of the root, penetrating less than half the distance between the surface and the pulp; the resorption was neither symptomatic nor progressive in nature. It may even have been the result of preoperative or postoperative orthodontics. These factors indicate that even if surgery is the cause of root resorption, it is not necessarily of clinical significance, and further treatment is not required. Tooth sensibility after orthognatic surgery has been reported in a number of studies.G11,19,25-27 Several of these have involved Le Fort I osteotomies without sagittal osteotomies. In 14 to 18 months after such a
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AND ANDERSON
FIGURE 4. Tooth showing
small apical
root resorption
[arrow]
procedure, the teeth of the maxilla seem to regain their sensibility in 50% to 100% of the cases. Recently, Shehab Al-Din et a126assessed 119 teeth in 20 patients for dental nerve disturbance after Le Fort osteotomy without sagittal osteotomy by means of an electric pulp tester. After 6 months, 78% of the teeth responded positively. Kahnberg and Engstriimz7 examined tooth sensibility to electrical stimulation in 44 patients after one-segment Le Fort I osteotomy. Thirty of the examined teeth were central and lateral incisors. At the l&month follow-up, 100% of the incisors (n = 20) had regained pulp sensibility. Our results are in accordance with the previously mentioned findings. However, in a study of 27 cases, Tajima’ reported that the central and lateral incisors showed the poorest recovery after Le Fort-type osteotomies and Le Fort-type fractures, with only 23% and 50% recovery, respectively, 14 months postsurgery. Some of the patients had a sagittal osteotomy or a fracture, which prompted Tajima to speculate that the vertical bone cut may have influenced recovery of the pulpal responses, but it is the direct trauma to the
incisors that may have played the most significant role. The pulpal condition of teeth adjacent to maxillary interdental osteotomies has been surveyed by a number of authors. Johnson and Hind& examined the vitality of teeth in 17 patients who underwent subapical osteotomies. Thirty-five (21%) of 169 teeth did not respond to electrical or thermal stimulation; 25 of these were adjacent to an osteotomy site. Only four teeth were radiographically or clinically abnormal, and all of these were obviously injured during surgery. Hutchinson and MacGregor8 also studied tooth survival after subapical osteotomies. Forty-nine (91%) of 58 teeth in the mobilized segment responded to electrical stimulation 6 months after surgery in a subapical anterior maxillary group. However, not one of the transposed teeth was lost in the postoperative follow-up. Pepersack9 investigated tooth vitality after alveolar segmental osteotomy. In the study, 89 teeth were in the mobilized maxillary fragment adjacent to a vertical osteotomy without extraction or adjacent to a supplementary midline osteotomy. Eighty-two (92%) teeth reacted positively to cold stimulation 12 months postoperatively. Pepersack’s conclusions confirm that the largest number of nonreacting teeth are found in the mobilized fragment and adjacent to the vertical osteotomy when no extraction is conducted in the osteotomy site. After performing anterior segmental osteotomies, Theisen and Guernsey’ 1 surveyed 1 I6 teeth in 16 patients, of which 72 were in maxillary segments. They confirmed the risk categories, with a lower percentage of positive responses for the teeth in the mobilized segment adjacent to the osteotomy. Vedtofte and Nattestadlg reported 51 patients who had Le Fort I osteotomy performed. Of 617 teeth tested for pulpal sensibility, 38 were central incisors adjacent to interdental osteotomies. Two (5%) of these teeth failed to respond to electrical stimulation. After Le Fort I osteotomy without an interdental osteotomy, all of the central incisors regained normal sensibility reaction. All the previously cited studies on vertical osteotomies indicate that the teeth adjacent to the osteotomy are those with the highest risk for damage to the pulpal sensibility, whereas those teeth in the mobilized segment not adjacent to the osteotomy are the least involved. In the current study, four (11%) of the central incisors adjacent to the vertical osteotomy were nonresponsive, in comparison with the lateral incisors not adjacent to the osteotomy cut that all responded to electrical stimulation. Although the difference is not statistically reliable, these results are consistent with the studies mentioned previously. However, all the nonresponsive teeth did not show any other pathological signs and did not require further treat-
528 ment. Nevertheless, these teeth should be observed regularly for radiographic or symptomatic changes. The difference in alveolar bone level between the mesial and distal aspect of the central incisors and some of the sites adjacent to the midline osteotomy suggests that this is a postsurgical effect (Table 1). Future prospective studies are needed to further evaluate the alveolar bone level after midline osteotomies. Few studies in the oral and maxillofacial surgery literature have evaluated the periodontal status following interdental osteotomies. Carroll et al13investigated the effect of maxillary osteotomies on the periodontium in surgical and nonsurgical orthodontic patients. The surgery group was divided into patients having had nonsegmental maxillary osteotomies, two-piece maxillary osteotomies, and three-piece maxillary osteotomies. The two-piece subgroup had osteotomies performed between the central incisors. The investigators reported that tooth mobility was low in all groups and no significant differences were found. No differences in probing depth from that in the nonsegmental counterparts were noted at the sites of osteotomies made between the central incisors. These results are in accord with the current findings. Also in the Carroll et al study,‘3 there were no differences in attachment level when the osteotomies were made between the central incisors and in the nonsegmetalized counterparts. The attachment levels were calculated by adding gingival recession (measurement apical to the cementoenamel junction) and probing depths; no radiographs were used. The alveolar bone level in our study was measured from the cementoenamel junction on the radiographs and, therefore, these results are not comparable. We found a statistically significant loss of marginal bone. However, the magnitude of the marginal loss (0.4 mm) was not clinically meaningful and therefore should not intimidate the surgeon against performing midline osteotomies. No patient in our study required further periodontal treatment after the minimal loss of bone following surgery. Dorfman and Turvey’* evaluated osseous crestal changes after maxillary and mandibular segmental osteotomies in 10 patients. They concluded that adequate working width for the osteotomy is 3 mm or more. In the surgical method described in this article, all interdental osteotomies were performed without tooth extraction. It is important to stress that the osteotomy was performed with a thin osteotome for the last 10 mm from the alveolar crest. This procedure might have caused minimal damage to the marginal periodontal tissue. Diiker and Schillil” analyzed periodontal damage due to osteotomy in the alveolar process in beagle dogs. They found that superficial osteotomies that extended to the periodontal ligament, but did not
MIDLINE OSTEOTOMY AND DENTAL COMPLICATIONS involve the hard tissues, healed completely without discernible damage to the periodontium. When the damage extended into the cementum and dentin, partial healing occurred, with functionally favorable results. If the osteotomy entered the pulp, formation of secondary dentin occurred. Optimal healing appeared to be take place in the middle and apical thirds of the root after the resumption of normal function. These conclusions are in agreement with our findings concerning the two teeth that showed small injuries in the apical third caused by the cutting instrument.
References
5. 6. 7. 8. 9. 10.
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17. 18.
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SteinhauserEW: Midline splitting of the maxilla for correction of malocclusion. J Oral Surg 30:413, 1972 West RA, Epker BN: Posterior maxillary surgery: Its place in the treatment of dentofacial deformities. J Oral Surg 30:562, 1972 Bell WH, Epker BN: Surgical-orthodontic expansion of the maxilla.&nJOrthod70:517,1976 Krekmanov L, Lilja J, Ringqvist M: Maxillary osteotomy without the use of postoperative intermaxillary fixation: A clinical and cephalometric study. Stand J Plast Reconstr Surg 23:125, 1989 Krekmanov L, Kahnberg K-E: Transverse surgical correction of the maxilla. J Craniomaxillofac Surg l&332, 1990 JohnsonJV, Hinds EC: Evaluation of teeth vitality after subapical osteotomy. J Oral Surg 27:256, 1969 Tajima S: A longitudinal study on electric pulp testing following Le Fort type osteotomy and Le Fort type fracture. J Maxillofac Surg 3~74, 1975 Hutchinson D, MacGregor AJ: Tooth survival following various methods of sub-apical osteotomy. Int J Oral Surg 1:81, 1972 Pepersack WJ: Tooth vitality after alveolar segmental osteotomy. J Maxillofac Surg 1:85, 1973 Leibold DG, Tilson HB, Rask KR: A subjective evaluation of the re-establishment of the neurovascular supply of teeth involved in anterior maxillary osteotomy procedures. Oral Surg 32:531, 1971 Theisen FC, Guernsey LH: Postoperative sequelae after anterior segmental osteotomies. Oral Surg 41:139, 1976 Summers L, Booth DR: The early effects of segmental surgery on the human pulp. Int J Oral Surg 4:236, 1975 Carroll WJ, Haug RH, Bissada NF, et al: The effects of the Le Fort I osteotomy on the periodontium. J Oral Maxillofac Surg 50:128, 1992 Dorfman HS, Turvey TA: Alteration in osseous crestal height following interdental osteotomies. Oral Surg 48:120, 1979 Ware WH, Ashamalla M: Pulpal response following anterior maxillary osteotomy. Am J Orthod 60: 156, 1971 Diiker J, Schilli W: Rapid orthodontics after subtotal osteotomy: Biologic foundation and clinical implications, in Bell WH (ed): Surgical Correction of Dentofacial Deformities-New Concepts. Philadelphia, PA, Saunders, 1985, pp 465-489 Lanigan DT, Hey JH, West RA: Aseptic necrosis following maxillary osteotomies: Report of 36 cases. J Oral Maxillofac Surg 48:142, 1990 Geylikman YB, &tun J, Leroux BG, et al: Effects of Le Fort I osteotomy on human gingival and pulpal circulation. Int J Oral Maxillofac Surg 24:255, 1995 Vedtofte P, Nattestad A: Pulp sensibility and pulp necrosis after Le Fort I osteotomy. J Craniomaxillofac Surg 17: 167, 1989 Andersson L, BlomlGf 1, Lindskog S, et al: Tooth ankylosis: Clinical, radiographic and histological assessments. Int J Oral Surg 13:423, 1984 Eggen S: Simplification and standardization of intra-oral radiography. Quintessence Int 1:93, 1970 de Jongh M, Barnard D: Sensory nerve morbidity following Le Fort I osteotomy. J Maxillofac Surg 14:10, 1986
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1999
Discussion Periodontal and Pulpal Condition of the Central Incisors After Midline Osteotomy of the Maxilla Jet-old S. Goldberg, DDS Dean, School of Dentistry, Professor of Oral & Maxillofacial Surgery, Case Western Reserve University( Cleveland, Ohio; e-mail: [email protected]
This article, which looks at periodontal and pulpal health after a segmental, midline osteotomy, is one of several publications on this or related subjects that are referenced by the authors. The various articles tend to use different parameters of pulpal or gingival health and often measures of those parameters are carried out in different ways or with different devices. It is unfortunate that none of the published research is an attempt to reproduce a previously done experiment at a different center. Be that as it may, this study successfully supports the notion that segmental osteotomies that are performed concomitantly with Le Fort I osteotomies rarely have clinically significant detrimental effects on either the pulpal or periodontal tissues. These positive results are true throughout the dental arch as well as specifically at the interdental osteotomy site. Concerning root resorption, it would have been helpful for this study to have a control group of orthodontically treated patients who did not have surgery with which to compare results. The article by Carroll et al, cited in this article, is an example of a similar report that falls short of presenting data that is reproducible.’ It investigated the parameters of plaque index, gingival index, tooth mobility, width of keratinized tissue, probing depth, and gingival recession. The experimental group had segmental orthognathic surgery and was compared with a control group of patients who had orthodontic treatment without surgery. This investigation looked at patients having osteotomies between the premolars and canines as well as between the central incisors. The only statistically significant findings were in the probing depths of the teeth adjacent to the osteotomies between the canines and the premolars and in the width of the keratinized tissue. However, no probing depths at the osteotomy sites exceeded 3 mm so that the statistically significant finding is of no clinical concern. The greater width of attached gingiva in the experimental group is probably related to the high incidence of vertical maxillary excess in the experimental population.
In addition to the main topic of this article, the authors support a technique using multiple palatal osteotomies to depress and widen the maxillary vault. In the original article, by Krekmanov and Kahnberg, describing this technique there is little to support its use over one or two parasagittal osteotomies.2 Krekmanov and Kahnberg reported horizontal relapse and soft tissue lacerations. It would be interesting to know what additional information there is to support this approach. The concept is interesting, but I do not know if the additional osteotomies really make a difference. The authors also describe using a chisel in the midline to complete the bone cut between the central incisors for a distance of 10 mm above the crest of the interdental ridge. In most cases, there is some indication of a suture line between the centrals. Placing a chisel in this line (or where you would imagine this line to be, if it does not exist) and carrying the osteotomy above the level of the teeth is both safe and easy. This should reduce the chance of direct injury to teeth about which the authors’ expressed concern. In reviewing the literature, it appears that earlier reports (in the 1970s) indicate a higher incidence of pulpal and periodontal complications than more recent investigations. Perhaps we have identified approaches that diminish the incidence of these complications. Using a flexible chisel for interdental osteotomies, requiring that there is adequate space between tooth roots before surgery, being careful not to damage the palatal soft tissue, designing splints that do not impinge on soft tissue, performing model surgery that depicts reasonable movement of segments, and planning procedures that do not exceed the physiologic or mechanical limits of the tissues are all things that may reduce the incidence of pulpal and periodontal complications. It is true that even with good planning and careful execution, vascular compromise may occur. However, it is infrequent that major vascular compromise leads to the loss of teeth or supporting bone. This and other articles show that it is also infrequent that more subtle complications, such as loss of alveolar crest, pulpal degeneration, or loss of the level of gingival attachment are a problem. One can express concern about the parameters that were chosen or the methods of measurement or about the existence or appropriateness of the controls but, at this point, it is reasonable to say that midline osteotomies performed con-