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Implants in Conjunction With RemovablePartial Dentures: A Literature Review
Eitan Mijiritsky, DMD
Many authors have writtenabout the merits of implant-supported complete overden-
tures, which have been used clinicallywith high success rates for the fullyedentulous patients. The completeoverdenture has proven to be an im-provement over conventional com-plete prostheses with respect tochewing efficiency, patient comfort,and satisfaction.14 The context of in-creasing life spans and evidence fromvarious national dental health surveysin industrialized countries indicatethat the proportion of edentulous peo-ple will continue to decline and thatmore people will retain more teeth intoold age.5,6 Projections based on datafrom such surveys6,7 suggest a declinein tooth loss but an increased need formanagement of partial edentulism inpatients with compromised oral orgeneral health status. This trend ofage-related increased tooth retentionsuggests that partially edentulous co-horts will be older than before andprobably less disposed than youngerpeople to such treatment with exten-sive tooth or implant-supported fixedpartial dentures. Consequently, socio-economic factors and populationtrends suggest increased future treat-ment needs with different partial pros-theses.8 A well-constructed removablepartial denture can be an excellenttreatment alternative.9 12 Yet, thesepatients deserve the best esthetic andfunctional results possible. In thesecases, a limited number of strategi-cally placed dental implants in con-
junction with the remaining naturalteeth can establish a favorable remov-able partial denture design by signifi-cantly reducing the effect of thereciprocal arm and improving the ful-crum line position. When an implantor a limited number of implants isused to support the removable partialdenture, additional retention isachieved, and the need for unestheticbuccal retentive arm clasps is avoidedat the esthetic zone.1315
The aim of this article is to reviewthe literature regarding the use of im-plants with removable partial denturesin partially edentulous patients and toevaluate the evidence-based indica-tions for this clinical approach.
LITERATURE REVIEWA MEDLINE/PubMed database
search was limited to peer-reviewedarticles published in English between1990 and 2006, focusing on the use ofimplants with removable partial den-tures and related features such as re-sidual ridge resorption, need anddemand for prosthodontic treatment,and cost-effectiveness of dental treat-
ment, all related to implants and re-movable partial prostheses. The digitalsearch was supplemented with ahand search to identify relevantpeer-reviewed English articles pub-lished in dental journals and textbookson removable partial dentures. Fewcase reports, 1 short-term retrospec-tive follow-up (14 years), and 1 lon-gitudinal clinical study (27 years)were identified.
CONSIDERATIONS FOR THEKENNEDY CLASS I ANDII SITUATIONS
Common complaints associatedwith the Kennedy class I (bilateral freeend) and II (unilateral free end) re-movable partial dentures situations arelack of stability, minimal retention,unesthetic retentive clasping, and dis-comfort upon loading.16
Kelly17 in 1972 described the com-bination syndrome as a common prob-lem associated with the mandibularbilateral partial denture distal extensionopposing a maxillary complete denture,which is characterized by downgrowthof the maxillary tuberosities, papillary
Private practice, Tel Aviv, Israel; Visiting Professor, DentalSchool, University of Chieti-Pescara, Chieti, Italy.
ISSN 1056-6163/07/01602-001Implant DentistryVolume 16 Number 2Copyright 2007 by Lippincott Williams & Wilkins
Although the benefits of implant-borne removable prostheses arereadily apparent for the fully eden-tulous patient and have been welldocumented, there is a paucity ofstudies concerning the combinationof implants with removable partialdentures in partially edentulous pa-tients. The aim of this article is toreview the literature regarding im-plants with removable partial den-tures and evaluate the evidence forthis clinical approach. A MEDLINE/PubMed search from 1990 to 2006,
focusing on the use of implants withremovable partial dentures and re-lated features, was supplementedwith a hand search to identify rele-vant peer-reviewed English articlespublished in dental journals andtextbooks on removable partialdentures. (Implant Dent 2007;16:1)Key Words: removable partial den-tures, dental implants, partiallyedentulous patients, cost-effective,treatment alternative
IMPLANT DENTISTRY / VOLUME 16, NUMBER 2 2007 1
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hyperplasia, resorption of the premax-illa, overeruption of the mandibularanterior teeth, and resorption of the pos-terior mandible.18 These signs may befound in 24% of the population wearinga maxillary complete denture opposinga bilateral distal extension partial den-ture.19 Kelly17 discussed various possi-bilities to avoid combination syndrome.He proposed using roots of anteriormandibular teeth to support an overden-ture. He also mentioned the option ofusing endodontic implants to preservequestionable roots for support in theposterior part of the mandible. Contro-versy exists regarding the potential de-velopment of combination syndromealso in those patients using an implant-supported overdenture with 2 anteriorimplants, since this type of restorationcan act as a bilateral distal extensionsituation.2022 A posterior implant stopwould most likely eliminate the poten-tial for this to happen. An obvious ad-vantage of an implant with a removablepartial denture in this case is that theextension of the bases can be reduced,since the implant provides the same sta-bility as a terminal abutment would in aKennedy class III situation. The alteredcast impression, a standard technique formaximizing posterior support in theclass I situation, can be omitted aswell.23 One of the most challenging sit-uations to treat with a removable partialdenture is in certain cases classified asKennedy class II, when there are abut-ments only on 1 side of the arch.The long lever arm to the unilateraledentulous side results in an unstableremovable prosthesis, if treated conven-tionally. A strategically placed dentalimplant can establish an improved re-movable partial denture design by sig-nificantly reducing the effort arm andimproving the fulcrum line position.
Tissue-ward rotation during func-tion, around the fulcrum line createdbetween the abutment teeth closest tothe edentulous area, is prevented.13
Keltjens et al24 in 1993 and Haltermanet al25 in 1999 described a number ofclinical cases where 2 implants wereused to assist in the support of a man-dibular bilateral distal extension re-movable partial denture opposed by amaxillary complete denture. Each im-plant was placed in the first molararea, and on 1 occasion, only verticalsupport was derived from the implants
with no retentive elements, while onanother occasion, additional retentionwas provided by magnets, which wereattached in the distal extension denturebase over the implants. From a short-term experience, using implants, theauthors claim was to maintain the in-tegrity of the vertical dimension ofocclusion and prevent degenerativechanges that could have led to whatKelly17 described as the combinationsyndrome. Giffin26 in 1996 reported acase where a Kennedy class II man-dibular arch was restored using a com-bination of a single molar implant atthe edentulous alveolar crest with anextracoronal resilient attachment tosupport and retain a removable partialdenture. The patient claimed that theimplant-supported side of the pros-thesis felt more natural and waspreferred for mastication over the tooth-supported side.
Mitrani et al23 in 2003 described aretrospective study with a follow-up ofat least 1 year to a maximum 4 yearsof 10 partially edentulous patients un-satisfied with their removable partialdentures (Kennedy class I and II).They were treated with posterior os-seointegrated implants to providestability and/or retention of the remov-able prostheses, eliminating the needfor clasps when possible. The authorsperformed a follow-up clinical evalu-ation consisting of patient satisfaction,radiographic examination, and softtissue health. Results indicated consis-tent increased satisfaction in all pa-tients, minimal component wear, noradiographic evidence of excessivebone loss, and stable peri-implant softtissues. Kuzmanovic et al27 in 2004described a case where a Kennedyclass I mandibular arch was restoredusing a combination of bilateral singlemolar implants with ball attachmentsto support and retain a chromium-cobalt removable partial denture. Theauthors reported no complications af-ter 2 years.
RESIDUAL RIDGERESORPTION RELATED TOIMPLANTS AND REMOVABLEPROSTHESESGENERAL ASPECTS
There are clear indications and lit-tle doubt that removable dentures are
an important causative factor in thebone resorption process. This is sup-ported by studies showing significantdifferences in residual alveolar bonebetween edentulous subjects wearing,or not wearing, removable den-tures.28,29 Subjects not wearing den-tures had more remaining bone. Ingroups of patients who had been wear-ing complete mandibular dentures fordifferent lengths of time, the continu-ous bone resorption stopped in the ar-eas distal to the mental foramina afterthe patients had been provided withimplant-supported prostheses placedanterior to the foramina.30 Animalstudies have shown that continuouspressure from an experimental denturecaused bone resorption when exceed-ing a threshold value and that theresorbed bone was not reshaped whenpressure was discontinued.3133
Kordatzis et al34 in 2003 comparedthe posterior mandibular residual ridgeresorption in