Survival and complication rates of combined tooth-implant-supported fixed partial dentures

OBJECTIVES: The objective of this study has been to review the incidence of biological and technical complications in case of tooth-implant-supported fixed partial denture (FPD) treatments on the basis of survival data regarding clinical cases. MATERIAL AND METHODS: Based on the treatment documentations of a Bundeswehr dental clinic (Cologne-Wahn German Air Force Garrison), the medical charts of 83 patients with tooth-implant-supported FPDs were completely recorded. The median follow-up time was 4.73 (time range: 2.2-8.3) years. In the process, survival curves according to Kaplan and Meier were applied in addition to frequency counts. RESULTS: A total of 84 tooth-implant (83 patients) connected prostheses were followed (132 abutment teeth, 142 implant abutments (Branemark, Straumann). FPDs: the time-dependent illustration reveals that after 5 years, as many as 10% of the tooth-implant-supported FPDs already had to be subjected to a technical modification (renewal (n=2), reintegration (n=4), veneer fracture (n=5), fracture of frame (n=2)). In contrast to non-rigid connection of teeth and implants, technical modification measures were rarely required in case of tooth-implant-supported FPDs with a rigid connection. There was no statistical difference between technical complications and the used implant system. Abutment teeth and implants: during the observation period, none of the functionally loaded implants (n=142) had to be removed. Three of the overall 132 abutment teeth were lost because of periodontal inflammation. The time-dependent illustration reveals, that after 5 years as many as 8% of the abutment teeth already required corresponding therapeutic measures (periodontal treatment (5%), filling therapy (2.5%), endodontic treatment (0.5%)). After as few as 3 years, the connection related complications of implant abutments (abutment or occlusal screw loosening, loss of cementation) already had to be corrected in approximately 8% of the cases. In the utilization period there was no screw or abutment fracture. CONCLUSION: Technical complications of implant-supported FPDs are dependent on the different bridge configurations. When using rigid functional connections, similarly favourable values will be achieved as in case of solely implant-supported FPDs. In this study other characteristics like different fixation systems (screwed vs. cemented) or various implant systems had no significant effect to the rate of technical complications.     

A systematic review of the survival and complication rates of fixed partial dentures (FPDs) after an observation period of at least 5 years

OBJECTIVES: The objective of this systematic review was to assess the 5- and 10-year survival of implant supported fixed partial dentures (FPDs) and to describe the incidence of biological and technical complications. METHODS: An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on FPDs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by two reviewers. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions. RESULTS: The search provided 3844 titles and 560 abstracts. Full-text analysis was performed for 176 articles resulting in 21 studies that met the inclusion criteria. Meta-analysis of these studies indicated an estimated survival of implants in implant-supported FPDs of 95.4% (95 percent confidence interval (95% CI): 93.9-96.5%) after 5 and 92.8% (95% CI: 90-94.8%) after 10 years. The survival rate of FPDs supported by implants was 95% (95% CI: 92.2-96.8%) after 5 and 86.7% (95% CI: 82.8-89.8%) after 10 years of function. Only 61.3% (95% CI: 55.3-66.8%) of the patients were free of any complications after 5 years. Peri-implantitis and soft tissue complications occurred in 8.6% (95% CI: 5.1-14.1%) of FPDs after 5 years. Technical complications included implant fractures, connection-related and suprastructure-related complications. The cumulative incidence of implant fractures after 5 years was 0.4% (95% CI: 0.1-1.2%). After 5 years, the cumulative incidence of connection-related complications (screw loosening or fracture) was 7.3% and 14% for suprastructure-related complications (veneer and framework fracture). CONCLUSION: Despite a high survival of FPDs, 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 FPDs. More studies with follow-up times of 10 and more years are needed as only few studies have described the long-term outcomes.     

Biological and technical complications and failures with fixed partial dentures (FPD) on implants and teeth after four to five years of function

The aim of this study was to compare the frequency of biological and technical complications with fixed partial dentures (FPDs) on implants, teeth and as mixed tooth-implant supported FPDs over 4 to 5 years of function. All implants belonged to the ITI Dental Implant System. Group I-I (implant FPD) included 33 patients with 40 FPDs, group T-T (tooth FPDs) 40 patients with 58 FPDs, group I-T (mixed tooth-implant FPDs) 15 with 18 FPD. Of the bridge abutments 144 were teeth and 105 were implants. The median number of units replaced by the FPDs was 3 (range 2-14). The mean age of the patients was 55.7 years (range 23-83). Complete failures resulted in the loss of one FPD in each group. Two implants were lost due to fracture secondarily to development of a bone defect. One tooth had a vertical fracture and 1 tooth was lost due to periodontitis. Biological complications (peri-implantitis, PPD > or = 5 mm and BOP+) occurred at 9.6% (10) of the implants. This number was, however, reduced to 5% if the threshold for definition of peri-implantitis was set at PPD > or = 6 mm and BOP+. Biological complications occurred in 11.8% (17) of the abutment teeth (NS compared to implants); 2.8% (4) had secondary caries, 4.9% (7) endodontic problems and 4.1% (6) had periodontitis (PPD > or = 5 mm, BOP+). Ten out of 32 patients with a general health problem indicated a biological complication, whereas 9 out of 53 patients with no general health problem had a biological complication (chi 2: NS). Statistically significantly more technical complications were found in FPDs on implants (chi 2, P < or = 0.05). The technical complications were associated with bruxism. Out of 10 bruxers 6 had a technical complication whereas 13 out of 75 non-bruxers had such a complication (chi 2 < or = 0.01). Extensions were associated with more technical complications (13 out of 35 with extensions versus 9 out of 81 without). In conclusion, favourable clinical conditions were found at tooth and implant abutments after 4-5 years of function. Loss of FPD over 4-5 years occurred at a similar rate with mixed, implant or tooth supported reconstructions. Significantly more porcelain fractures were found in FPDs on implants. Impaired general health status was not significantly associated with more biological failures but bruxism as well as extensions were associated with more technical failures.     

Prosthetic treatment planning on the basis of scientific evidence

Summary  The objective of this report is to summarize the results on survival and complication rates of different designs of fixed dental prostheses (FDP) published in a series of systematic reviews. Moreover, the various parameters for survival and risk assessment are to be used in attempt to perform treatment planning on the basis of scientific evidence. Three electronic searches complemented by manual searching were conducted to identify prospective and retrospective cohort studies on FDP and implant-supported single crowns (SC) with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions. Meta-analysis of the studies included indicated an estimated 5-year survival of conventional tooth-supported FDP of 93·8%, cantilever FDP of 91·4%, solely implant-supported FDP of 95·2%, combined tooth-implant-supported FDP of 95·5% and implant-supported SC of 94·5% as well as resin-bonded bridges 87·7%. Moreover, after 10 years of function the estimated survival decreased to 89·2% for conventional FDP, to 80·3% for cantilever FDP, to 86·7% for implant-supported FDP, to 77·8% for combined tooth-implant-supported FDP, to 89·4% for implant-supported SC and to 65% for resin-bonded bridges. When planning prosthetic rehabilitations, conventional end-abutment tooth-supported FDP, solely implant-supported FDP or implant-supported SC should be the first treatment option. Only as a second option, because of reasons such as financial aspects patient-centered preferences or anatomical structures cantilever tooth-supported FDP, combined tooth-implant-supported FDP or resin-bonded bridges should be chosen.     

A systematic review of the 5-year survival and complication rates of implant-supported single crowns

OBJECTIVES: The objective of this systematic review was to assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological and technical complications. METHODS: An electronic MEDLINE search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on SCs with a mean follow-up time of at least 5 years. Failure and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5-year proportions. RESULTS: Twenty-six studies from an initial yield of 3601 titles were finally selected and data were extracted. In a meta-analysis of these studies, survival of implants supporting SCs was 96.8% [95% confidence interval (CI): 95.9-97.6%] after 5 years. The survival rate of SCs supported by implants was 94.5% (95% CI: 92.5-95.9%) after 5 years of function. The survival rate of metal-ceramic crowns, 95.4% (95% CI: 93.6-96.7%), was significantly (P=0.005) higher than the survival rate, 91.2% (95% CI: 86.8-94.2%), of all-ceramic crowns. Peri-implantitis and soft tissue complications occurred adjacent to 9.7% of the SCs and 6.3% of the implants had bone loss exceeding 2 mm over the 5-year observation period. The cumulative incidence of implant fractures after 5 years was 0.14%. After 5 years, the cumulative incidence of screw or abutment loosening was 12.7% and 0.35% for screw or abutment fracture. For supra-structure-related complications, the cumulative incidence of ceramic or veneer fractures was 4.5%. CONCLUSION: It can be concluded that after an observation period of 5 years, high survival rates for implants and implant-supported SCs can be expected. However, biological and particularly technical complications are frequent.     

Technical complications of implant-supported fixed partial dentures in partially edentulous cases after an average observation period of 5 years

OBJECTIVES: The purpose of this prospective long-term study was to evaluate the incidence of the most common technical problems, namely screw loosening, screw fracture, fracturing of veneering porcelain and framework fracture in implant-supported fixed partial dentures (FPDs), and assess the survival and success rate (event-free survival) after 5 years of function. MATERIALS AND METHODS: In 76 partially edentulous patients, a total of 205 3i-implants (machined surface) were placed and restored with 112 implant-supported FPDs (46 single crowns, 81 splinted crowns, seven FPD bridges and 23 FPDs with cantilevers). The survival rate of FPDs supported by implants was 94.5% (CI-95: 90.1-98.8) after an average observation period of 5 years. The success rate (event-free survival) of the FPDs was 80% (CI-95: 87.3-72.7). After an observation period of 5 years the cumulative incidence of screw loosening was 6.7% (CI-95: 1.8-11.5), the cumulative incidence for screw fracture was 3.9% (CI-95: 0.1-7.7). Fracture of the veneering porcelain occurred in 5.7% (CI-95: 1.2-10.2) of all FPDs. Fracturing of the suprastructure framework was rare (1%; CI-95: 0-2.9). The overall complication incidence after 5 years was highest in the group of FPDs with cantilever, which showed the lowest success rate 68.6% (CI-95: 50-87.3), followed by single crowns (77.6%; CI-95: 53.3-100) and splinted crowns (86.1%; CI-95: 59.5-100). No complication occurred in FPD bridges. CONCLUSION: Fixed partial dentures supported by 3i-implants showed low technical complications rates, the most common being loosening of the abutment screw. Managing these complications can cause extra amount of chair-side time and patient dissatisfaction.     

Implant supported fixed partial dentures survival rate high, but biological and technical complications common

DATA SOURCES: PubMed (1966-April 2004) provided the primary data source along with the bibliographies from identified articles and reviews. Manual search of eight relevant journals (published 2001-2003) provided a further source of data. STUDY SELECTION: As there were no randomised controlled trials comparing implant therapy with conventional reconstructive dentistry, English language prospective and retrospective cohort studies were selected if; they had a mean follow-up of >/=5 years; included patients who were clinically examined at follow-up; reported details on suprastructures and described at least one-third of reconstructions as fixed partial dentures (FPDs). DATA EXTRACTION AND SYNTHESIS: Two independent reviewers screened articles for inclusion. Disagreements were resolved by discussion and agreement determined by kappa. Data were extracted on the survival proportions of the reconstructions and on biological and technical complications. Biological complications included disturbances in the function of the implant characterized by a biological process affecting the supporting tissues. Technical complications denoted mechanical damage of implants, implant components, or the suprastructures. The number of events for all categories was identified and the corresponding total exposure time of the reconstruction calculated. Failure and complication rates were calculated by dividing the number of events by the total exposure time. RESULTS: Twenty-one studies of implant supported FPDs, reporting on 16 patient cohorts were included. Of the studies, 16 were prospective and five retrospective. A total of 1336 FPDs supported by 3578 oral implants were involved. Meta-analyses gave an estimated implant survival of 95.4% (95% CI 93.9-96.5) after 5 years and 92.8% (95% CI 90-94.8) after 10 years. Implant failure rate was 48% lower (P=0.006) in the more recent studies. The estimated survival for the FPDs was 95% (95% CI 92.2-96.8) after 5 years and 86.7% (95% CI 82.8-89.8) after 10 years. Four studies provided information on the number of patients free from complications - after 5 years 61.3% (95% CI 55.3-66.8) had suffered no minor or major complications. A random effects Poisson model revealed the rate of biological complications for patients treated with implant supported FPDs to be 8.6% (95% CI 5.1-14.1) after 5 years. For technical complications the cumulative 5 year complication rate varied from 0.4% for implant fracture to 13.2% for veneer fracture. CONCLUSIONS: Although survival rate for implant supported FPDs is high, biological and technical complications are relatively common.     

Bone level change at implant-supported fixed partial dentures with and without cantilever extension after 5 years in function

OBJECTIVE: The aim of this study was to retrospectively analyze whether the inclusion of cantilever extensions increased the amount of marginal bone loss at free-standing, implant-supported, fixed partial dentures (FPDs) over a 5-year period of functional loading. MATERIAL AND METHODS: The patient material comprised 45 periodontally treated, partially dentate patients with a total of 50 free-standing FPDs supported by implants of the Astra Tech System. Following FPD placement (baseline) the patients were enrolled in an individually designed supportive care program. A set of criteria was collected at baseline to characterize the FPDs. The primary outcome variable was change in peri-implant bone level from the time of FPD placement to the 5-year follow-up examination. The comparison between FPDs with and without cantilevers was performed at three levels: FPD level, implant level, and surface level. Bivariate analysis was performed by the use of the Mann-Whitney U-test and stepwise regression analysis was utilized to evaluate the potential influence of confounding factors on the change in peri-implant bone level. RESULTS: The overall mean marginal bone loss for the implant-supported FPDs after 5 years in function was 0.4 mm (SD, 0.76). The bone level change at FPDs placed in the maxilla was significantly greater than that for FPDs in the mandible (0.6 versus 0.2 mm; p<0.05). No statistically significant differences were found with regard to peri-implant bone level change over the 5 years between FPDs with and without cantilevers at any of the levels of comparisons. The multivariate analysis revealed that the variables jaw of treatment and smoking had a significant influence on peri-implant bone level change on the FPD level, but not on the implant or surface levels. The model explained only 10% of the observed variance in the bone level change. CONCLUSION: The study failed to demonstrate that the presence of cantilever extensions in an FPD had an effect on peri-implant bone loss.     

Bone level changes at axial- and non-axial-positioned implants supporting fixed partial dentures. A 5-year retrospective longitudinal study

AIM: The aim of this study was to retrospectively analyze the potential influence of implant inclination on marginal bone loss at freestanding, implant-supported, fixed partial dentures (FPDs) over a 5-year period of functional loading. MATERIAL AND METHODS: The material comprised 38 periodontally treated, partially dentate patients with a total of 42 free-standing FPDs supported by implants of the Astra Tech System. Mesio-distal inclination of the implants in relation to a vertical axis perpendicular to the occlusal plane was measured with a protractor on standardized photographs of the master cast. The two tail quartiles of the distribution of the implants with regard to the implant inclination were defined as axial-positioned (mean 2.4 degrees; range 0-4 degrees) and non-axial-positioned implants (mean 17.1 degrees; range 11-30 degrees), respectively. For FPDs supported by two implants, both the mesial-distal and buccal-lingual inter-implant inclination was measured. The primary outcome variable was change in peri-implant bone level from the time of FPD placement to the 5-year follow-up examination. Comparison between axial- and non-axial-positioned implants was performed by the use of a Mann-Whitney U-test. Spearman's correlation analysis was used to analyze relationships between inter-implant inclination (mesial-distal and buccal-lingual) and 5-year bone level change on the FPD level. RESULTS: The 5-year mean bone level change amounted to 0.4 mm (SD 0.97) for the axial and 0.5 mm (0.95) for non-axial-positioned implants (P>0.05). For the FPDs supported by two implants, the mean inter-implant inclination was 9.2 degrees (1-36 degrees) in the mesial-distal direction and 6.7 degrees (0-24 degrees) in the buccal-lingual direction. Correlation analysis revealed lack of statistically significant correlation between inter-implant inclination (mesial-distal and buccal-lingual) and 5-year bone level change (r=-0.19 and r=-0.32, respectively). CONCLUSION: The study failed to support the hypothesis that implant inclination has an effect on peri-implant bone loss.     

Technical and biological complications/failures with single crowns and fixed partial dentures on implants: a 10-year prospective cohort study

OBJECTIVES: To assess prospectively over 10 years the incidences of technical and/or biological complications and failures occurring in a cohort of consecutive partially edentulous patients with fixed reconstructions on implants of the ITI Dental Implant System. METHODS: Eighty-nine patients were available, 34 (38.2%) were male, 55 (61.8%) were female. At the 10-year examination (range 8-12 years), they were 58.9 years old (range 28-88 years). RESULTS: Single crowns (SC): 48 patients had been restored with 69 SC on 69 implants. Five of the implants with the crowns were lost because of biological failures. Two crowns (2.9%) were remade because of technical failures. Total failure amounted to seven (10%). Implant borne fixed partial dentures (I-I FPD): In 29 patients who had been restored with 33 implant borne suprastructures, the total number of failed I-I FPD was 2 (6.1%). Tooth-implant borne fixed partial dentures (I-T FPD): In 21 patients, 22 mixed tooth-implant borne reconstructions were constructed. The number of failed FPD reached 7 (31.8%). Statistically significantly fewer biological failures occurred with I-I FPD compared with the I-T FPDs (ANOVA, Bonferroni, P=0.022). The I-T FPDs experienced statistically significantly more frequent technical failures compared with the other two groups of suprastructures (P=0.003, 0.031). Consequences of complications: The occurrence of loss of retention as a complication increased the odds ratio (OR) to 17.6 (P<0.001) to end up in a technical failure. Similarly, the event of a porcelain fracture increased the OR for the suprastructure to be a failure at 10 years to 11.0 (P< or =0.004). Treatment of periimplantitis increased the OR to 5.44 (P< or =0.011) to result in a biological failure compared with implants in which this type of treatment was not applied. CONCLUSION: The three groups of suprastructures demonstrated marked differences in their patterns of failures and complications. Complications increased the risk for failure. Support by CRF, University of Berne, Switzerland.     

Prosthetic complications in fixed endosseous implant-borne reconstructions after an observations period of at least 40 months

One hundred and seventy-two fixed reconstructions (317 prosthetic units), made on 283 ITI implants in 105 patients (age range 25-86 years) with a minimum follow-up period of 40 months, were taken into the study to analyse technical complication rate, complication type and costs for repair. The mean evaluation time was 62.5 +/- 25.3 months. Eighty were single crowns and 92 different types of fixed partial dentures (FPDs). In 45 cases the construction was screw retained and in 127 cases cemented with zinc phosphate cement or an acrylic-based cement. Complications occurred after a minimum period of 2 months and a maximum period of 100 months (mean: 35.9 +/- 21.4 months). Fifty-five prosthetic interventions were needed on 44 constructions (25%) of which 88% in the molar/premolar region. The lowest percentage of complications occurred in single crowns (25%), the highest in 3-4 unit FPDs (35%) and in FPDs with an extension (44%). Of the necessary clinical repair, 36% was recementing and 38% tightening the screws. Of all interventions, 14% were classified as minor (no treatment or <10 min chair time), 70% as moderate (>10 min but <60 min chair time) and 14% as major interventions (>60 min and additional costs for replacement of parts and/or laboratory). For seven patients the additional costs ranged from euro 28 to euro 840. Bruxing seemed to play a significant role in the frequency of complications. Longer constructions seemed to be more prone to complications. The relatively high occurrence of technical complications should be discussed with the patient before the start of the treatment.     

A 2‐year report on maxillary and mandibular fixed partial dentures supported by Astra Tech dental implants. A comparison of 2 implants with different surface textures.

In 50 partially edentulous patients, 133 (48 maxillary; 85 mandibular) Astra Tech dental implants of 2 different surface textures (machined; TiO‐blasted) were alternately installed, supporting 52 fixed partial dentures (FPDs). Before abutment connection 2 machined implants (1 mandibular; 1 maxillary) were found to be non-osseointegrated and were replaced. Another implant could not be restored due to a technical complication. Two FPDs were remade because of technical complications, both because of abutment fractures. Thus, after 2 years in function, the cumulative survival rates were 97.7% and 95.7% for implants and prostheses, respectively. There was no statistically significant difference in survival rate between the 2 types of implants, 100%(TiO‐blasted) vs 95.3%(machined), P =0.24. After 2 years in function, when both jaw and type of implants were combined, the mean (SD) marginal bone loss was 0.24 (0.69) mm. No statistically significant difference in bone loss was found between the 2 tvues of implant after 2 years of loading, 0.04 (0.82) mm, P >0.30.     

Retrospective survival analysis of 3-unit fixed-fixed and 2-unit cantilevered fixed partial dentures

To evaluate the cumulative survival (CS) rates of fixed partial dentures (FPDs) retained by full-veneer retainers, and those of resin-bonded FPDs provided by graduating dental students for the replacement of a single missing tooth. In 168 patients, 61 3-unit fixed-fixed FPDs and 25 2-unit cantilevered FPDs retained by full-veneer retainers, and 77 3-unit fixed-fixed resin-bonded FPDs and 47 2-unit cantilevered resin-bonded FPDs, were examined for their retention and integrity. The periodontal health, endodontic status and coronal tissues of all abutment teeth were also evaluated. The survival rates of these various designs were analysed with the Kaplan-Meier method. The mean age of all FPDs was 31 months. At 48 months after their insertion, 3-unit FPDs retained by full-veneer retainers had a CS rate of 82%, followed by 2-unit resin-bonded FPDs at 81%, 2-unit FPDs retained by full-veneer retainers at 77%, and 3-unit resin-bonded FPDs at 63%. No significant difference was found between the four designs (P>0.05). Up to both 48 and 60 months, the most common causes of failure were endodontic for FPDs retained by full-veneer retainers, and dislodgement for resin-bonded FPDs. The 3-unit fixed-fixed FPDs retained by full-veneer retainers had the most favourable prognosis after 48 months for replacing a single missing tooth, but the difference between designs was not statistically significant.     

90% of fixed partial dentures survive 5 years. How long do conventional fixed partial dentures (FPDs) survive and how frequently do complications occur?

DATA SOURCES: PubMed (1966-April 2004) provided the primary data source along with the bibliographies from identified articles and reviews. STUDY SELECTION: As there were no randomised controlled trials, English language prospective and retrospective cohort studies were selected if they had a mean follow-up of >/=5 years, included patients who were clinically examined at follow-up, reported details on suprastructures and described at least one-third of reconstructions as fixed partial dentures (FPDs). DATA EXTRACTION AND SYNTHESIS: Two independent reviewers screened articles for inclusion. Disagreements were resolved by discussion and agreement determined by kappa. Three reviewers extracted data on the survival and success of the reconstructions and on biological and technical complications. Studies deemed sufficiently similar by design were pooled using negative binomial regression with robust standard errors. Ten-year survival risks were calculated using exp(-10 x failure rate) and 10-year failure risks using 1-S(10). RESULTS: 17 retrospective and two prospective cohort studies including 1764 patients with 3548 FPDs analyzed in total. Meta-analysis was undertaken and after exclusion of one outlier a 10-year FPD survival of 92% was estimated. Only four studies provided information on FPD success - pooled complication rate was 34.1/1000 FPD years (95% CI 16-74). Exclusion of one outlier resulted in an estimated 10-year success of 81.1%. Considering biological complications, the estimated 10-years risk for caries at abutments was 9.5% (95% CI 4.6-89.9) while that for FPD loss due to caries and periodontal disease were 2.6% (95% CI 1.6-4.2) and 0.5% (95% CI 0.1-2.2), respectively. Estimated 10-year risks for technical complications were: 6.4% (95% CI 3.9-10.4) for loss of retention; 2.1% (95% CI 1.4-3.2) for loss of FPD due to abutment fracture and 3.2% (95% CI 1.5-6.5) for material fractures. CONCLUSIONS: Estimated success and survival rates for conventional FPDs largely confirm those of previous reviews. Technical complications such as loss of retention, which have not been reviewed before, resulted in a greater risk of FPD loss than did biological complications.     

An overview of zirconia ceramics: basic properties and clinical applications

Zirconia (ZrO2) is a ceramic material with adequate mechanical properties for manufacturing of medical devices. Zirconia stabilized with Y2O3 has the best properties for these applications. When a stress occurs on a ZrO2 surface, a crystalline modification opposes the propagation of cracks. Compression resistance of ZrO2 is about 2000 MPa. Orthopedic research led to this material being proposed for the manufacture of hip head prostheses. Prior to this, zirconia biocompatibility had been studied in vivo; no adverse responses were reported following the insertion of ZrO2 samples into bone or muscle. In vitro experimentation showed absence of mutations and good viability of cells cultured on this material. Zirconia cores for fixed partial dentures (FPD) on anterior and posterior teeth and on implants are now available. Clinical evaluation of abutments and periodontal tissue must be performed prior to their use. Zirconia opacity is very useful in adverse clinical situations, for example, for masking of dischromic abutment teeth. Radiopacity can aid evaluation during radiographic controls. Zirconia frameworks are realized by using computer-aided design/manufacturing (CAD/CAM) technology. Cementation of Zr-ceramic restorations can be performed with adhesive luting. Mechanical properties of zirconium oxide FPDs have proved superior to those of other metal-free restorations. Clinical evaluations, which have been ongoing for 3 years, indicate a good success rate for zirconia FPDs. Zirconia implant abutments can also be used to improve the aesthetic outcome of implant-supported rehabilitations. Newly proposed zirconia implants seem to have good biological and mechanical properties; further studies are needed to validate their application.     

Clinical study of the internal gaps of zirconia and metal frameworks for fixed partial dentures

The aim of this clinical study was to compare the internal gaps between abutment teeth and posterior fixed partial dentures (FPDs) fabricated utilizing milled zirconia and cast gold-alloy frameworks. As part of an ongoing randomized controlled clinical trial, 32 three-unit FPDs (16 zirconia and 16 metal-ceramic) in 25 patients were randomly selected for adaptation measurements. During the bisque-stage ceramic try-in, an A-silicone impression material was placed between the abutment teeth and the framework. The internal gap, corresponding to the thickness of the replica, was measured under magnification at the following locations: cervical, axial, and occlusal (cusp-tips and central). The internal gaps of FPDs with zirconia frameworks were significantly larger in cervical, axial, and centro-occlusal regions (cervical: 189.6 ± 71.8  μ m vs. 118.6 ± 31.5  μ m; axial: 140.5 ± 38.3  μ m vs. 95.7 ± 18.1  μ m; and centro-occlusal: 192.0 ± 66.5  μ m vs. 153.1 ± 69.8  μ m). The cervical gaps next to the pontics were significantly larger compared with those of the outer walls in both types of FPDs (zirconia: mean difference 67.7 ± 114.7  μ m; metal-ceramic: mean difference 30.0 ± 71.2  μ m). Posterior three-unit FPDs incorporating milled zirconia frameworks exhibited larger internal gaps than those constructed using conventional metal-ceramic techniques.     

All-ceramic fixed partial dentures. Studies on aluminum oxide- and zirconium dioxide-based ceramic systems

BACKGROUND: The development of refined, tougher, and stronger ceramic core materials in recent years has led to the wider use of new, strong all-ceramic systems based on oxide ceramics. Results from in-vitro studies investigating the use of oxide ceramics in shorter all-ceramic fixed partial dentures (FPDs) have been positive, but clinical studies and additional in-vitro studies are needed to confirm the advisability of such procedures. AIMS: One aim of this thesis was to investigate whether alumina-based and zirconia-based material systems are adequate for use in shorter (< or = five-unit) FPDs and to evaluate the clinical results. Additional aims were to investigate how to achieve optimal fracture strength in an all-ceramic FPD by varying the try-in procedure, the cervical shape of the abutments, and the support of the FPD (abutment teeth or dental implants). The final aim was to compare the strength of a zirconia material system with that of an alumina equivalent with known long-term clinical performance. MATERIALS AND METHODS: Two clinical studies investigating one alumina-based and one zirconia-based material system were performed. Twenty posterior, three-unit FPDs (glass-infiltrated alumina) were followed for 5 years and 20 three-five-unit FPDs (HIP zirconia) for 2 years. Long-term follow-ups were made after 11 +/-1 (glass-infiltrated alumina) and 3 years (HIP zirconia). In three in-vitro studies, the following variables were investigated: (1a) the flexural strength of porcelain specimens depending on whether they were exposed to saliva before the glaze firing (n=20) or first after the glaze firing (n=20), (1b) the fracture strength of three-unit all-ceramic FPDs (glass-infiltrated alumina) supported by abutments prepared with cervical shoulder preparations (n=9) and abutments with cervical chamfer preparations (n=9), (2) the fracture strength of crowns (n=30) made of a zirconia material system (densely sintered zirconia) and of crowns (n=30) of an alumina material system (densely sintered alumina) that had undergone three different pre-treatment modalities (water storage only; water storage and cyclic pre-loading; water storage, cyclic pre-loading, and thermocycling), (3) the fracture strength of all-ceramic FPDs (densely sintered alumina) supported by simulated teeth (n=12) or by dental implants (n=12). RESULTS: The success rate of the clinical alumina study was 90% after 5 years. Six (+/-1) years later (after a total of 11 +/-1 years), the success/survival rate was 65%. In the second clinical study, the success rates of the 2- and 3-year follow-ups were 100%. In the three in-vitro studies, the following results were found: (1a) the mean flexural strength of the specimens in the group that was exposed to saliva first after glazing was significantly higher (P < 0.001) than that of the specimens in the group that was exposed to saliva before glazing, (1b) the FPDs luted on shoulder preparations resisted higher loads than the FPDs luted on chamfer preparations (P = 0.051), 2) total fractures were more frequent in the alumina than in the zirconia group (P < 0.001), 3) FPDs loaded on implants resisted higher loads (mean = 604 N, SD=184 N ) than FPDs loaded on abutment teeth (mean= 378 N, SD=152 N, P = 0.003). CONCLUSIONS: This thesis justifies the use of shorter alumina- (< or = three-unit) and zirconia-based (< or = five-unit) FPDs as the clinical results are acceptable. The clinical performance of alumina is, however, not as good as that of comparable high-gold alloy based porcelain-fused-to-metal FPDs concerning fracture resistance. Within the limitations of the in-vitro studies: Saliva exposure of porcelain before glaze firing should be avoided to optimize the strength of the porcelain. Shoulder preparations can be beneficial for the strength of all-ceramic FPDs compared to chamfer preparations, as can support by dental implants compared to abutment teeth. The fracture mode of alumina crowns (total fractures) differs from that of zirconia crowns (veneer fractures), suggesting that the zirconia core is stronger than the alumina core.     

Survival and complication rates of combined tooth-implant-supported fixed and removable partial dentures

PURPOSE: The aim of this study was to assess and compare clinical outcome results of tooth-implant-supported fixed and removable partial dentures in a selected population group of partially edentulous patients. Biological and technical complications were recorded and reviewed. MATERIALS AND METHODS: A retrospective analysis of the dental charts of 224 patients (174 men, 50 women) with a mean age of 51.3 years was carried out. The evaluation included details regarding the survival and technical complications of the prescribed prostheses, as well as the biological and technical complications associated with both types of abutments used, ie, teeth and implants. RESULTS: A total of 229 prostheses were supported by 459 implants and 449 teeth. They were monitored for a period of 2 to 10 years (median follow-up time: 6.7 years). At the end of the different observation periods, 14% of the tooth-implant-supported prostheses had undergone technical modifications, with no statistical difference in the occurrence of technical complications between the 2 types of prosthesis. Three of the functionally loaded implants were removed, while 23 abutment teeth were lost (15 had undergone endodontic treatment). Abutment teeth with a reduced attachment level after prosthesis insertion were significantly affected by biological complications (P = .04). CONCLUSIONS: The survival data for both types of prosthesis were comparable to prostheses supported solely by implants. There was no difference in the complication rate between primary splinting (fixed) and secondary splinting with telescopic systems (removable). A greater risk of biological complications was recorded for endodontically treated abutments or teeth with a reduced attachment level.     

Ceramic implant abutments for short-span FPDs: a prospective 5-year multicenter study

PURPOSE: A prospective, randomized, controlled 5-year multicenter study evaluated the long-term clinical function of CerAdapt ceramic abutments compared to titanium abutments on Br?nemark implants supporting short-span fixed partial dentures (FPD). MATERIALS AND METHODS: Initially, 105 Br?nemark implants were placed in a total of 32 patients at three different clinics; 103 implants remained after initial healing. Fifty-three ceramic and 50 titanium abutments were connected to support 36 FPDs, 19 on ceramic and 17 on titanium abutments. RESULTS: Thirty patients with 29 FPDs were examined after 5 years. There was a cumulative success rate of 97.2% for FPDs (94.7% for ceramic and 100% for titanium abutment-supported FPDs). One of 53 ceramic and none of 50 titanium abutments failed, giving survival rates of 98.1% and 100%, respectively. There was a mean marginal bone loss of 0.3 mm and 0.4 mm, respectively, for ceramic and titanium abutments. Soft tissues around abutments and adjacent teeth appeared healthy, and no significant differences were recorded for mucosal bleeding and plaque between ceramic and titanium abutments. Crown margins at FPD insertion were positioned as follows: 21% submucosally, 33% at the mucosal margin, and 46% supramucosally. Changes in mucosal level were recorded at 12% of the abutments, with 73% of all changes recorded at ceramic abutments. There was a balance between more or less exposed crown margins during the first 2 years, in contrast to the 2- to 5-year period, when all changes meant less exposed margins. CONCLUSION: Safe long-term functional and esthetic results can be achieved with CerAdapt alumina ceramic abutments on Br?nemark implants for short-span FPDs.