|Year : 2014 | Volume
| Issue : 1 | Page : 38-43
A retrospective clinical study of implant-retained prosthetic partial dentures: A follow up investigation
David Joseph, Sébastien Gallina, Nathalie Paoli, Neal Miller, Jacques Penaud, Pascal Ambrosini
Department of Periodontology and Oral Implantology, Faculty of Dentistry, Nancy, France
|Date of Web Publication||19-Apr-2014|
Faculté d'Odontologie, 96 Avenue de Lattre de Tassigny BP 50208 54004, Nancy
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: To evaluate the 5-year follow up of implants placed in partially edentulous patients restored with removable partial dentures.
Materials and Methods: In this retrospective study, survival rates and clinical outcomes of implants placed for retention of removable partial dentures in 36 partially edentulous patients were observed.
Results: The survival rate of the implants after a 5-year follow up was 98%. The clinical mean scores for plaque, calculus, gingivitis and bleeding were very low at all evaluation periods. Significant differences between results at successive time periods can be observed only between the plaque index at 1 year and the plaque index at 5 years. Peri-implant probing demonstrated a deepening of pockets over time. However, the changes were not statistically significant between the two evaluation periods. During the first year of function an average attachment loss of 0.4 mm was observed. During the next 4 years the average progression of PPD was about 0.1 mm per year.
Conclusion: After 5 years, implants retaining removable partial dentures showed good survival rates and clinical stability. Using implants is a good solution to improve the satisfaction of patients with removable partial dentures; nonetheless this prosthetic solution demands strict surveillance of the patient and is time consuming for the clinician.
Keywords: Dental implants, overdenture, removable partial denture
|How to cite this article:|
Joseph D, Gallina S, Paoli N, Miller N, Penaud J, Ambrosini P. A retrospective clinical study of implant-retained prosthetic partial dentures: A follow up investigation. J Dent Implant 2014;4:38-43
|How to cite this URL:|
Joseph D, Gallina S, Paoli N, Miller N, Penaud J, Ambrosini P. A retrospective clinical study of implant-retained prosthetic partial dentures: A follow up investigation. J Dent Implant [serial online] 2014 [cited 2022 Aug 12];4:38-43. Available from: https://www.jdionline.org/text.asp?2014/4/1/38/130970
| Introduction|| |
In an edentulous mandible, an implant supported dental prosthesis is the recommended treatment to ensure sufficient prosthetic rehabilitation. , A 5-year prospective study  evidences that two implants seem to be sufficient to provide retention for patients satisfied with their overdenture. The need to treat partially edentulous patients will rise with the extension of life expectancy and the increase in tooth retention. This patient need meets common prosthetic treatment objectives, such as increased occlusal support, vertical dimension restoration and improved masticatory efficiency and esthetics. Different treatment options are proposed for the partially edentulous patient.  Implant-supported fixed partial prostheses and single crowns are nowadays a successful treatment alternative to partial dentures and fixed restorations. However, little research involves removable partial dentures (RPD) on implants and natural teeth. In this case, implants are used to complete stabilization and retention of partial denture in addition to clasps and occlusal rests on classical metallic bases.
Implants are used to improve the RPD support, enhance retention and stability, preserve the residual ridge, eliminate the need for unaesthetic clasp assemblies, and modify unfavorable configurations. In a retrospective study Mitrani et al. 2003.  report on ten patients treated with unilateral and bilateral distal-extensions RPDs supported by implants, with resilient elements. The authors demonstrate a consistently increased satisfaction of all patients, no radiographic evidence of bone loss, and stable peri-implant soft tissue after at least a 1 year clinical follow up period.
The aim of this retrospective study is to analyze the clinical results and treatment outcomes (survival rates, condition of hard and soft peri-implant tissues, patient satisfaction, prosthetic and post operative complications) of maxillary and mandibular partial dentures supported by teeth and one or more implants. The long-term survivals of this treatment modality, as well as abutment teeth survival and patient satisfaction, are evaluated.
| Materials and Methods|| |
Patient selection and treatment
36 partially edentulous patients (24 women, 12 men, mean age 60, 38 years, range 37-79 years) were enrolled in the study. They were all referred by their dentists to our private clinic, for full dental rehabilitation. Inclusion criteria for the clinical trial were a post-extraction period of at least 6 months and a minimum of four teeth per arcade. Patients with a history of radiotherapy in the head and neck region or previous implant placement were excluded as well as smokers. The patients were informed about the treatment options: One, two or tthree endosseous implants to retain an over denture or classical means for prosthetic retentions. [Table 1] summarizes data of the group at baseline.
All patients received initial periodontal treatment including oral hygiene instruction, full mouth root scaling, extraction of lost teeth, treatment of caries and endodontic procedures when necessary. When periodontal pockets persisted after this first treatment stage, surgical elimination of the periodontal pockets was performed using full thickness flaps. All patients underwent professional periodontal maintenance with a bi-annual recall. No implants were inserted until complete healing of the alveolar bone crest and stabilization of the periodontal tissues.
The implants were inserted under local anesthesia, following the procedure describe by the manufacturer (Biomet 3I™). All the implants had sand blasted, acid etched surfaces (Implants certain strait full osseotite). One, two or three implants were placed, depending to the edentulous status of the patient. Generally, a single implant, placed directly behind the most distal remaining tooth, was used in each edentate posterior sector. Exceptionally, two were placed when the edentulous section was particularly long. In no bilateral edentate cases 4 implants were necessary.
All implants were placed in a 2-stage procedure by one of two qualified surgeon (AP, SG). For every patient, all the implants (left and right) were placed during the same surgery. Full thickness gingival flaps were sutured over the implants after their placement. Standard postoperative treatment consisted of analgesics (paracetamol or ibuprofen ad libidum), mouth rinses (0.2% chlorhexidin three times a day) and antibiotics (amoxicillin, 2 g per day for 6 days). The distribution of the lengths of the implants is presented in [Table 2].
Three months after implant placement, second stage surgery (muco-gingival tissue management when necessary and placement of the healing abutment) was performed. For weeks later, standard prosthetic treatment was carried out: A metallic base partial denture retained by one, two or three attachments. In addition to the implants, teeth were selected as abutments to provide support for the RPD based on their pulpal and periodontal conditions, the presence and type of coronal restoration, the need for indirect retention, and the distribution and number of abutments and implants in the arch. The Locator® type attachment was used for all cases included in this study. Abutment choice depended on the thickness of the gingiva and the interdental space available. The healing abutments were removed and replaced with the adequate Locator attachment. The metal plaque of the RPD was confectioned on a plaster model including the Locator attachment transfer, and the final position of the female part of the attachment was done directly with the patient, fixing the attachment on the metallic plaque with self-curing acrylic resin. The good of the RPD adaptation with the oral mucosa and its occlusal harmony are controlled before leaving the patient with his useful RPD.
The clinical analysis included a number of parameters. Lost implants were scored after placement. The presence of plaque was evaluated according to Mombelli et al. (1987)  : Score 0: No plaque detection, score I: Plaque detected with a probe, score II: Plaque can be seen, score III: Abundance of plaque. The presence of calculus (score I) or the absence (score 0) was recorded. The Löe and Silness gingival index  was used to qualify the degree of peri-implant inflammation. Score 0: Normal peri-implant mucosa; score I: Mild inflammation, slight change in color, slight edema; score II: Moderate inflammation, redness, edema and glazing; score III: Severe inflammation, marked redness and edema, ulceration. The bleeding index describe by Mombelli et al. 1987  was used (score 0: No bleeding on probing, score I: Isolated bleeding spots, score II: Confluent line of blood along the mucosa, score 3: Profuse bleeding. Probing depth was measured at four sites of each implant (mesial, buccal, distal, lingual) using a periodontal probe; the distance between the marginal border of the mucosa and the tip of the periodontal probe were scored as the probing depth. All these data (plaque, calculus, gingival inflammation and probing) have been registered during a specific appointment with the patient, 8 to 20 days after delivery of the news RPD. Prosthetic and postoperative incidents or complications were recorded during the follow-up.
The data were analyzed using t-tests for the continuous data and Mann-Whitney tests for the ordinal data. Statview® software was used for all data analyses.
| Results|| |
Implant survival rate
During the healing period prior to abutment connection , two implants were lost. After a period of 2 months, two new implants were placed and hence successfully osteointegrated, both patients were included in the study for follow up evaluation. One implant was lost 3 years after loading and the decision was made not to replace it. The survival rate of the implants 5 years after loading is 98% (cumulative survival).
The clinical data are presented in [Table 3]. The mean scores for plaque, calculus, gingivitis and bleeding were very low at all evaluation periods. No significant differences between results at successive time periods can be observed, except between the plaque index at 1 year and the plaque index at 5 years. It can be noticed that the mean plaque index at 5 years is lower than the mean plaque index observed after 1 year. During the two evaluation periods, peri-implant probing evidences a deepening of pocket depths with time. During the first years of function an average attachment loss of 0.4 mm can be observed. During the next 4 years the average progression of PPD is about 0.1 mm per year.
|Table 3: Mean values of Plaque-Index (score 0-3), calculus-index (score 0-1), Gingival – Index (score 0-3), bleeding-index (score 0-3), pocket probing depth (PPD) in mm at T-0 (after placement of the overdenture) at T-1 (one year after placement of the overdenture) and at T-5 (fi ve years after placement of the overdenture)|
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Prosthetic and postoperative follow-up
The prosthetic and surgical needs during the 5 year observation period are listed in [Table 4]. The main prosthetic intervention consisted in changing loose clips for new ones, with a 5 year average of 2 per patient. Repair of the denture base or elements occurred rather frequently. There was almost no need of surgical interventions, due to the stability of the marginal tissues around the implants.
|Table 4: Prosthetic and surgical maintenance during the 5 year follow-up|
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| Discussion|| |
A significant proportion of RPD fabricated for partially edentulous patients are not worn.  Studies demonstrated that elderly patients are really satisfied with their RPD only if it adds a significant number of occlusal units to their dentition. 
Subjected to occlusal forces a RPD tend to produce rotational movements and the resulting torque forces detrimental to the abutment teeth and the soft tissues. Occlusal discrepancies and pain in the soft tissues under the connector or denture base are frequently observed. , In addition, the resorption of the edentulous ridge gradually continues because of constant pressure from the denture base.  The instability of a denture due to these occlusal modifications and ridge resorption can be solved by the placement of one to three implants.  An implant placed posteriorly virtually eliminates the clinical problems often associated with a tooth and tissue supported RPD.
There are few studies evaluating implants used with residual teeth and supporting removable partial dentures. Keltjens et al. (1993)  reported two cases of implants combined with a cast metal RPD providing occlusal stability and improved functional comfort. Grossmann et al. 2008,  in a retrospective case series of implants used to restore partially edentulous patients with implant-supported RPDs reported a survival rate of 95.5% at 31 months with two implant failures. The survival rate of implants in the present retrospective study is 98%. This percentage is comparable with other prospective studies which have reported survival rates of implants supporting an overdenture ranging from 86 to 98.8%. ,,,[,19],,
The results presented here are similar to those of the meta-analysis published by Pjetursson et al. 2004  They indicated an estimated survival rate of implants in implant-supported fixed partial restorations (implant supported crown or bridge in non edentulous patients) of 95.4% after 5 years. In a systematic review of the literature, Jung et al. 2008  analyzed the survival and complication rate of implant-supported single crowns. In a meta-analysis of the data extracted from the 26 studies selected, survival of implants supporting single crowns was 96.8% after 5 years of function. They reported peri-implantitis and soft tissue complications in conjunction with 9.7% of the single crowns. They concluded that high survival rates for implants and implants supporting single crowns can be expected, nevertheless, biological and technical complications are frequent.
The mean index scores for plaque, calculus, and gingival bleeding were very low at the 1 year and 5 year evaluations. The scores are comparable with other studies using the same criteria. ,, All the patients received complete periodontal treatment with oral hygiene education, initial therapy with full mouth root scaling, surgical pocket removal if necessary and professional maintenance. This strict periodontal preconditioning provided healthy peri-implant tissues. In a retrospective study Evian and et al. 2004  compared implant survival and patterns of implant failure in periodontally compromised and periodontally healthy patients. The overall survival rate for implants placed in the periodontally healthy group was 93.7%, compared to 90.6% in the periodontally compromised group. Two types of implant failure were identified. The first was failure to osseointegrate. This type of failure occurred early in treatment and appeared to be related to smooth-surface implants placed in bone of low density. Failures of this type were distributed equally between the two groups. The second type of failure was related to peri-implantitis. It was observed most often with implants with hydroxyapatite surfaces, occurred as the result of a progressive condition, and was most prevalent in the periodontally compromised patient group. Periodontal status and maintenance are of great importance for the survival rates of implants placed in partially dentate patients.
In our study, no smokers were included, essentially because very few current smokers asked for an implant retained RPD during the enrolment period. This can be an important point in the 5 years results for the clinical index scores and survival rates of the implants. In a 10 year retrospective study, Aglietta et al. 2011,  analyzed the marginal bone level change around implants in periodontally healthy and periodontally compromised tobacco smokers. They concluded that after 10 years, implants placed in tobacco smokers with a history of treated periodontitis and supportive therapy program yielded lower survival rates and higher marginal bone loss rates compared to implants placed in periodontally healthy smokers, independent of the implant system used. These results support the affirmation that the association of smoking and periodontal disease confers a bad prognosis for implants stability.
Several studies have evaluated patient satisfaction and prosthodontics maintenance of dentures retained by osteointegrated implants with either bar-clip or ball-spring matrices devices. , They concluded that the cast framework had no influence on the satisfaction expressed or on adjustments and repairs. Subjects were very satisfied with their new dentures, and no differences in prosthetic complications were observed for the two attachment systems. Implant-supported over dentures with bar or ball attachments may be considered to be reliable methods in the treatment of the edentulous individuals. Cavallaro and Tarnow 2007  presented five consecutives cases in which unsplinted implants remained osteointegrated when used to retain removable over denture prostheses with limited palatal coverage. It appears that contemporary implants can function in an unsplinted manner to retain maxillary removable over dentures with partial palatal coverage. They used the Locator attachment system, like in the present study. Ohkubo et al. 2008  evaluated the effectiveness of placing one implant per edentulous area in a distal position. They concluded that a simple attachment technique yielded a stable extension, very satisfactory for all patients in terms of comfort, chewing, retention and stability.
In our study the major prosthetic maintenance concern during the 5-year follow up was changing loose clips for new ones, with an average of two per patient during the 5 year observation period. Repair of the denture base or elements occurred rather frequently. These results confirm that the patient has to be followed whichever type of implant supported frame is used. During the 5 year observation period none of the implants were fractured. In Pjeturson and et al. 2004  meta-analysis complications included implant fractures, connection-related and suprastructure related complications. The cumulative prevalence of implant fractures after 5 years was 0.4%. The cumulative prevalence of connection-related complications (screw loosening or fracture) was 7.3% and 14% for suprastructure-related complications (veneer and framework fracture). The authors concluded that despite a high survival of fixed partial dentures, biological and technical complications are frequent. This, in turn, means that substantial amounts of chair time have to be accepted by the clinician following the incorporation of implant-supported fixed partial dentures. We agree with this conclusion, that implant supported RPD are a time-consuming treatment mode.
| Conclusion|| |
This study, demonstrates that osteointegrated implants associated with removable partial dentures can provide 5 year survival rates similar to those obtained with implant supported partial restorations, full dentures stabilized by implants or implant supported single crowns. Use of implants for partially edentulous patients with removable dentures genuinely improves the satisfaction and comfort of patients. However, the clinician has to keep in mind that this type of treatment demands strict surveillance of the implanted patients for periodontal maintenance and technical purposes.
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[Table 1], [Table 2], [Table 3], [Table 4]