Osseointegration for elderly patients: The Toronto study

or elderly

Faculty of

pati

ChD, MS, DDS, MS, FRO(C), Dr mitt, MS& DDSb University of Toronto, Toronto, Ont., Canada

Dentistry,

Successful osseointegration promises a virtual panacea for the e~~~t~l~~~ ment. However, the impact of this technique on specific age groups is far from clear. In an attempt to determine the efficacy and effectiveness of ~rn~la~t-s~~posted prostheses in geriatric patients, the treatment outcomes of elderly patients already included in ongoing clinical trials were assessed. The fallowing ~re~irni~a~y observations were made: (1) being elderly is not a contraindication to long-term implant survival; (2) successful osseointegration can be maintained i pective a ~~~~e~t’s oral hygiene performance; and (3) diverse prosthesis de& amear feasible.

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be choice of fixed or removable prescriptions is largely determined by the number, location, and health status of‘tbe remaining teeth. However, the patient’s desire and motivation, in addition to economic concerns, have an impact on the clinical decision-making process. The introduction of controlled oral care maintenance programs aids in the longevity of even the most severely depleted deatition.’ Although such compromised dentitions can be re&ored with heroic efforts, extensive rehabilitation should be plarmed with great caution, given the unpredictability of possible sequelae that may be encourktered.2 A number of population groups, particularly elderly patients, cannot benefit from traditional efforts. These patients are already edentulous and wear complete dentures with varying degrees of success.3 Some older patients are only partially edentuious, but may not be able to avail themselves of t,be various methods for retention of their remaining teeth, Past clinical experience in treating geriatric patients with severe!y compromisedperiodontal health has led to the proposal of immediate denture therapy for such patients. Alternately, whenever strategically located teeth can be restored and retained, partial or complete overdenture therapy may be prescribed.3 Many texts and articles endorse the mechanical principles of partial and complete denture therapy.‘;3 When correctly applied, these principles will presumably lead to a happy coexistence between the host tissues of the patient

b&eve this is and the prostheses they support. ijenti&s true, despite evidence to the contrazy.“ Iz3 fact,, 46 cmii2 of tooth attachment and support mecktpniszn has been Teplaced by only a fraction of that amount, ~~~~o~~rn~te~~ 24 cm2 of potential d~~ture-bea~~~~ area ‘21 the riilaxilia, and 12 cm2 in the mandible. This is a fairly
--.Presented at The Toronto Symposium on Prosthodontic Treatment for the Geriatric Patient, Toronto, CM., Canada, December 1993. “Profkssor and Head, Department of Prosthodontics and Implant Prosthodontic Unit. Q&&ant Professor, Department of Prosthodontics and Implant Prosthodontic Unit. OF Copyright 2‘ 1994 by The Editorial Council of THE JOURNAL

In spite of the documentation and a:xdotd. claims for success of compbte denture therapy, patients and dentists often disagree about what c~‘n~tit~tes a successf~1 denture expeaience.8 eriterialporqU~~~J,,)?.BtaPld~ePde in denture fabrication have been articulated; however, these crit&a do not address ~at~e~~-~e~~~~e~ f~tors SU& as the patient’s ability to handle dentures nnl &a patient’s OpiCion about trealment oi-Itcome. They also do not take into

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Fig. 1. A and B, After stage 2 surgery, healing caps were attached to each transmucosal abutment. C and D, Tissue surfaces of patient’s existing dentures were relieved and (E and F) lined with temporary soft lining material, which resulted in immediate improved stability and support for prostheses.

attempts to establish valid and responsive outcome measures of prosthetic effectiveness have proved unreliable because of the difficulties in establishing quantifiable and reproducible parameters.s Most dentists identify anatomic, physiologic, and/or psychologic reasons as the cause of acute or chronic maladaptive prosthetic behavior. Attempts to cope with the problem by patient counseling, modifying and improv-

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ing denture fabrication techniques, and occasionally resorting to some type of preprosthetic surgical intervention, may still be inadequate, and the status of these patients usually ends up as maladaptive. Traditional preprosthetic surgical endeavors such as sulcus-deepening or ridge augmentation have, for the most part, sought to provide a comfortable enlargement of the denture-bearing area. Although this approach seems logi-

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cal in the context of our traditional associations of better prost~~etic prognoses with better ridge morphology, longitudinal d~~~~~e~tatio~ tbat endorses minimal morbidity and clinical ~.~e~~ive~es~ for the surgical methods has not been ~0I~~e~l~ng~~ Our research suggests that the provision of a stable prosthesis may be the most important determinant for complete denture therapy success, together with satisfying the esthetic expectations of the patient.7 The patients of t,he authors’ previous studies had one major feature in common: all were considered maladaptive. All of the paGents were edentulous for several years, and aumerous efforts were made to improve or replace their prostheses. The one stinctive feature which charaeterized these patients s that they were not happy with ~~ad~ti~~a~ ~rostbado~t~~ intervention, namely relines, occlusal adjustm.ents, and fabrication of new dentures. However, all of the patients reported a rapid resolution of their problems when denture stabilization occurred after the surgicai uncovering of the implants and attachment of the t~a~~rn~~~sa~ components (Fig. 1). This was found to be the same weigher the patient was treated with an electively removable prosthesis that only the dentist could remove or the treatment consisted of an overdenture (unpublished data). Several implant systems have been commercially available for decades, but the lack of scientific justification for their ~res~r~pt~o~ and long-term clinical effectiveness have u~d~r~~~~ed tbeir lack ofac~e~tance in clinical academia or practice. As a result, teaching implant prosthodontics had not been ~~orn~~e~t~~ featured in tke curriculum of most d schools. t~cbniq~e of osseo~~tegratio~ is based on a demonstrated rn~cha~ica~~ and perhaps even structural, interlocking of a functional commercially pure titanium implant and loaded bone.l* The stress distribution occurs from implant to ~urro~~din~ bone and resumed biologic type of “VeLcro” atta~bme~t is obse A proposed clinical defcores the significance of inition of o~seo~ntegratio~ u this interfacial osteogenesis (Fig. 2).l’ The work of Branemark et al.‘” ushered in a new era for the treatment of edentulous patients along with a new standard of therapeutic quality, ~redictab~Iity~ and longevity, which other implant systems must be measured against. While ongoing research into the exact nature of the attachment of the implant to host bone may yield even better elinieai methods to achieve osseointegration,the technique ogers the dentist an expanded clinical therapeutic repertoire (Table I). The clinical techniques for achieving and rna~~tain~~g~sseo~ntegrationare described extensively in the literature. The objective of osseointegrationis responseto the artificial tooth root, entiated and biomechanically adequate to resist oeclusalstresses(Fig, 3). Such an achievement appearsto depend on the following clinical protocol: 1. Careful surgery is required that doesnot compromise

Fi q Interface between host &me Lila iooth ri~3t analog hasbeendescribeda Qsseoi~tegra-~I~~ and is visualized aa closea~~~~xirnatio~ etween imp1ac.t:m bone,

the ~red~~t~b~~ty of a ~avo~~b~~healing responsea~ manifested by a subse~~~e~t,~,ve%a-,li~~zen-ciated host that. ale parIt should ern~~bas~~~~ system d not include a two-stage 1;the implant is not covered during the integrating period. Perhapsa mucoseJcovermgbetween rtion of the implant and th.e ~~~~~~~~~ of the ontic phaseis not m.andato~y,~xt~~~~~v~longaw-up will determine whether this premise is correct.~2 2. ~omrner~ial~~pure u~~l~~e~ titanium material is used. With this, the oxide layer that buil up over be metallic surfaceis what actually cont8.cTs the bone. This layer is purported to beneficially aEect the host tissue me.. sponse.Other metals with d~~~~e~~~ sr;rfaceskave a!.so been ~ro~osed,and early reports sul;gesfthat altematives to ~orn~~e~~~a~~y pure titanium 9%:’eo,uaUyviabie,*3

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of favorable treatment outcome for previous Id D, Fixed prosthesis is supported by five os-

3. Design of a root analog allows immediate stability of the implant and excellent scope for eventual stress distribution. Here too, different cylindrical designs appear to perform equally well, at least in the short term. 4. An unloaded healing phase for the implant is necessary to ensure a predictable optimal healing response. Even with systems such as ITI (Institute Strauman, Waldenburg, Switzerland) that do not have a covered phase, there is a 4- to 6-month integrating period before the prosthesis is made.14

ax?

5. Passive fit of the prosthetic superstructure and an ideal prosthetic occlusal relationship are standard objectives in prosthodontics. However, the absence of a resilient periodontal ligament support in tissue-integrated prostheses indicates a need for technical prosthodontic accuracy that may exceed what is required for natural tooth abutments. 6. Internationally documented clinical experiences have led to the proposal of success criteria, which remain the standard measure used in clinical research.r5 This synthesis of published information suggests that the issue of prosthodontic treatment for geriatric patients in the context of osseointegration, demands answers to three questions (Table II).

1. Can osseointegrated prescribed for elderly

implants patients?

be

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i hygiene became less importance as this patient’s , Mucosa was not adversely affected and patient e&s of implant rted prosthesis 11 years after original insertion. Tound implant remain relatively constant as seen in early (F) and Iate ~QQZ~~~Z~

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Fig. 5. Vertical line drawn bilaterally through zone 1 and zone 2. Presence of crucial anatomic may also distinguish two zones.

Table III. Comparison of the results of the Toronto study: The overall Toronto experience from 1979 to 1992 and the geriatric study Geriatric study

Number placed 207 Number lost 10 (4.8%) Number late loss 3 (1.5%)

Toronto study 5 - 10 years 274

21 (7.7%) 11 (4.0%)

Total Toronto experience 867 41 (4.7%) 25 (2.9%)

patient, is sparse.16 There is however, extrapolated evidence that confirms the beneficial results of this method when prescribed for patients 60 years of age and older. The original inclusion criteria in studies with the osseointegration technique were limited to maladaptive edentulous patients. I7 If the patient had any or all of these indications that led to the diagnosis of maladaptation, the patient was considered a candidate for treatment with osseointegration. The exclusion criteria were also clearly delineated. Given the absence of morbidity that has been reported, it was tempting to suggest that any geriatric patient whose systemic health does not preclude a minor oral surgical procedure may be considered a candidate for osseointegration. Age did not enter into either the inclusion or exclusion criteria. In the prospective Toronto study, initiated in 1978, the

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mental foramina marks junction between landmarks and difference in bone quality

veracity of Branemark’s claims were tested. The patient treatment group consisted of 46 edentulous patients with 49 implant-supported prostheses. Of these patients, 11 were elderly when their treatment was completed between 1979 and 1983. Since then, more elderly patients have been included in the ongoing studies on diverse applications of the technique. These patients, whose ages ranged from 60 to 81 years, were treated between 1984 and December 1992. These patients were selected with exactly the same measures used for selecting younger patients. In addition to the presence of adequate bone quantity in height and width to surround the implant, there was the requirement for a systemic health status compatible with any minor surgical procedure. Several elderly patients exhibited one or more systemic health problems that ranged from minor arthritis to osteoporosis to cardiovascular irregularities. If any of these health problems was in an uncontrolled state, treatment was delayed until such time that the patient’s health was stable and the physician’s approval to proceed was obtained. Although there is often a concern about the ability of the geriatric patient to withstand oral surgical procedures, it would appear that this is not necessarily valid. Doctor Holm-Pedersen analyzed previous studies carried out by Lindhe et a1.18 where they performed periodontal therapy procedures that included surgery in elderly subjects and concluded that although it is popularly believed that the

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i’ lg. 6. A and B, MaxiHary class II partial edensuirsm Xeated with irnplaat-s~~.~!p,?de~~.~ 74year-old man. C, Porcelain baked to metal prosthesis is supported by hsea Satisfying esthetics results. healing process is slower in elderly individuals, age-dependent differences in wound healing do not appear to affect the outcome.L9 .~s expected, any treatment group that includes postmenopausal women is likely to include people who have or are developing osteoporosis. Dao et aLso conclude that osteoporosis is not a contraindication for prescribing osseoiategratioc. Although osteoporosis results in a decrease in bone mass, especially in the long bones, these bones can repair and hea!. Kbadivi”’ studied elderly patients who suffered from cardiovascular disease and were treated with osseointegrated Jmplant-supported prostheses. His findings suggest that cardiovascular disease does not preclude a patient’s eligibility for osseointegrated implant surgery. The surgically related problems and complications en-

Tbe problems that can occur a&er ~~~~~~~~~~~ok’ the prostb.eiic phase of Lreat,ment range wx33 “hardware”

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7. A, Bilateral fixed prosthodontic class I partial edentulism.

Preliminary conclusions tissue interface

is no apparent

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decreased levels of oral hygiene, and implant loss. 2. There is no apparent correlation between bone loss around implants and recorded observed gingival and periodontal indices. 3. At present it appears that the pathogenesis of periodontal disease and that of lost osseointegration are dissimilar.

complications, such as fracture of the gold alloy screw that retains the prosthesis, to more biologic complications, the most serious of which is implant loss. The recall records of two groups of patients?, 23 were examined, patients who were elderly at the time their implants were placed and patients who were younger at the time of implant placement but are now in the geriatric age group. Patients in all age groups demonstrated similar numbers and ranges of complications that involved the hardware of the system. The number of fractured gold alloy screws and the number of fractured center screws were no higher for the elderly patients than they were for the younger patients, and the final prosthesis was not fractured or in 566

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man with (C) man-

need of repair any more often in the older patient group. Fracture of the implant itself is extremely rare and over the 14 years of the Toronto study has not occurred. The long-term success rate for patients studied who were geriatric at the time of stage I surgery and those who have since that time entered the geriatric age range was similar to the overall success rate. The later loss of an implant, that is, loss of the implant after it has been loaded with a prosthesis, is 1.5 % for all of these treated elderly patients. This figure compares quite favorably with the late loss data gathered from all treatment groups that represent a diversity of ages. A major concern was the soft tissue response that would occur after several years of wear as patients age. Throughout the time of the studies, various periodontal indices to monitor soft tissue health were used, and the bone level changes were measured. With the natural tooth, the presence of plaque, calculus, and increased numbers of bacteria may have a devastating effect. The nature of the junctional epithelial attachment, or lack of attachment, to the titanium abutment or transmucosal element is not known. Similar structures are present with natural teeth and titanium analogs, but the exact nature of their function has yet to be determined. Carmichael et a1.24 used histochemical techniques to obVOLUME

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serve the ?.mplant-soft tissue interface, and came to the preliminary hypothesis that the clinical immobility of the osseointegrated implant enhances the barrier function of the junctional epithelium and thereby contributes to the maintenance of healthy peri-implant mucosa. In a recent article: Leonhardt et al.“” argued for a similar hypothesis, which states that “failing implants might primarily be an ind~vid.~alIy-relayed problem with secondary involvement of site-specific components. Specific microorganisms may play little decisive role in initiating the processes but may still be of importance in maintaining destructive process around failing implants.” Both hypotheses were articulated previously in an article by Zarb and Albrektsson.26 Observations on the subject are summarized in Table IV. While it is true that inadequate levels of oral hygiene lead to a transient discomfort, this can be readily relieved by a period of careful cleaning. The frequency of this occurrence is rare, even in mouths where the level of oral hygiene is less than ideal (Fig. 4).

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of osseointegration rent prosthodontic ate treatment to geriatric patients?

be

Preliminary observations suggest an affirmative answer this question. Our early experience in Toronto was with the original use of osseointegration, that is, five or six implants placed in the edentulous mandible and then loaded with a fixed or electively removable prosthesis. For some patients whose implants were uncovered and fitted with transmucosal abutments in late autumn, there was a hiatus in treatment to accommodate winter vacations. The patients’ existing mandibular dentures were relieved on the tissue surface to provide space for the abutments plus healing caps and were lined with a temporary soft liner. All patients reported that these temporary overdentures resolved the problems that had originally led them to seek treatment. Therefore, it seemed reasonable to routinely prescribe two implants to support a removable complete denture. The inclusion and exclusion criteria for these patients remain the same as those for patients treated with five or six implants” The earliest overdenture patients were treated over a decade ago. Feine et al.” studied the relative satisfaction of patients who wear removable and fixed prostheses. Each patient was tested with both types of prostheses. Eight of the 15 patients were initially fitted with a fixed prosthesis, and seven were fitted with a removable overdenture. Part way through the experiment, there was a switch and each patient was then fitted with the other type of prosthesis. The patiems reported that the mastication time was shorter for all foods with patients who wore overdentures, and the EMG activity waslessfor patients who wore overdentures. The authors concluded that the long-bar overdenture is a more efficient prosthesisthan the fixed. Another consideration is that of maintenance requirements for the overdenture and fixed prosthesis.Hemmi.ngs to

et a128evaluated the follow-up ~eq~~.~r~~~~~~~,~ for overden tures and removable prostheses and Cound that, overdentures supported by a bar and clip assemb’!y required less frequent maintenance and were aiso less expensive. This was only a S-year retrospective s&y: but it is 3UF opinion that these findings will hold trze in !,he iong term. The most extensive and long-term siudies O?Ithe effkacy and effectiveness of osse~)i~te~~a~~~~~Imve been limited to zone I of the mandible and the maxillas. areas of the mouth that are likely to have better borne qualky and qu
ng elderly and edentalous has w;dermir~ed tne quallife for both the patient and the “,re&ng dent&& Pait tients have suffered because oi t.hei~ :ziorpkiogic and functional compromise, acd the d~x~tkt has suffered. becase of a lack of safe and predictably successful clinical modalities to prescribe. To date, our clinical studies sapper:- :;he conelusioa that neither advanced age itself nor the di.minished levels of oral hygiene that often accompany ii, are a!nne ~ontraindieaCons to a prescription for treatmene wi’l’iz os~~o~~lt~~~a~~~~~, Patients who were elderly at the time heir implants were placed and patients who have grown elderly since :mpianr. insertion have had irn~lant-su~~~~~ei~ prostheses of various designs fabricated for them. ‘T&se prostheses have functioned suecessi’uly over the yea-?-s.

THE

2 10.

I I. 12.

13. 14.

1.5. 16.

17.

18.

19.

20.

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prognostic aid for complete denture patients. J PROSTHET DENT 1969;22:20-9. Hillerup S. Mandibular vestibuloplasty-experimental and clinical studies. Copenhagen: University of Copenhagen, 1990. Brinemark P-I, Hansson BO, Adell R, Hreine U, Lindstrom d, Hallen 0, Ohman A. Osseointegrated implants in of the edentulous jaw experience from a ten-year period. Stockholm: Almquist and Wiksell, 1977. Albrcktsson ‘I’, Zarb GA. Current interpretations pf,the osseointegrated response: clinical significance. Int J Prosthodont 1993;6:95-105. Shroeder A, Van der Zypen E, Stich H, Sutter F. The reactions of bone, tissue and epithelium to endosteal implants with sprayed. Int J Oral Maxillofac Surg 1981;9:15-22. Johansson CB. On tissue reactions to metal implants [Doctoral dissertation]. Goteborg: University of Giiteborg, 1991. Buser D, Shroeder A, Sutter F, Lang NP. The new concept of IT1 hollow cylinder and hollow screw implants; Part 2. Clinical aspects, indications, and early clinical results. Int J Oral Maxillofac Implants 1988;3:173-81. Smith DE, Zarb GA. Criteria for success of osseointegrated endosseous implants. J PROSTHEX DE~VT 1989;62:567-72. Kondell PA, Nordenram A, Landt H. Titanium implants in the treatment of edentulousness: influence of patient’s age on prognosis. Gerodontics 1988;4:280-4. Zarb GA, Schmitt A. The longitudinal clinical effectiveness of osseointegrated implants: The Toronto study. Part I: Surgical results. J PROSTHET DENT 1996634X-7. , . Lindhe 6, Socransky SS, Nyman S, Westfelt E, Haffajee A. Effect of age on healing following periodontal therapy. J Clin Periodontol 1985;12:‘7’74-87. Helm-Pedersen P. Influence of age on tissue healing. In: Worthington P, Branemark P-I, eds. Advanced osseointegration surgery. Chicago: Quintessence Publishing, 1992;47-56. Dao TT, Anderson JD, Zarb GA. Is osteoporosis a risk factor for osseointegration of dental implants? Int J Oral Maxillofac Implants 1993;8:133-44.

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21. Khadivi V. The impact of cardiovascular disease on the success rate of the surgical phase of the osseointegration technique [Thesis]. Toronto: Faculty of Dentistry, University of Toronto, 1993. 22. Zarb GA, Schmitt A. The longitudinal clinical effectiveness of osaeointegrated dental implants: The Toronto study. Part III: Problems and complications encountered. J PROSTHhT DENT 1996$4:185-94. 23. Zarb GA, Schmitt A. Implant therapy alternatives for geriatric edentulous patients Gerodontology 1993;10:28-32. 24. Carmichael RP, Apse P, Zarb GA, McCulloch CA. Biological, microbiological, and clinical aspects of the peri-implant mucosa. In: Albrektason T, Zarb GA, eds. THe Br&nemark osseointegrated implant. Chicago: Quintessence Publishing, 1989;37-78. 25. Leonhardt A, Adolfsaon B, Lekholm U, Wikstrom M, Dahlen G. A longitudinal microbiological study on osseointegrated titanium implants in partially edentulous patients. Clin Oral Imp1 Res 1993;4:113-20. 26. Zarh GA, Albrektsson T. Osseointegration: a requiem for the periodontal ligament? Int J Periodont Res Dent 1991;11:88-91. 27. Feine JS, Maskawi K, De Grandmont P, Donahue WB, Tanguay R, Lund JP. Within-subject comparisons of implant-supported mandibular prostheses: evaluation of masticatory function. J Dent Res 1994 (Accepted for publication). 28. Hemmings KW, Schmitt A, Zarb GA. Implant-supported prostheses for the edentulous mandible: complications, maintenance and supplemental treatment. Int J Prosthodont 1994 (Accepted for publication). Reprint requests to: DR. GEORGE A. ZARH FACULTY OF DENTISTRY UNIVERSITY OF TORONTO 124 EDWARD ST. TORONTO, ONTARIO M5G lG6 CANADA

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