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Purpose: This retrospective study investigated the survival rate of 174 clasp-retained removable partial dentures (CR-RPDs) made at the Department of Prosthodontics of the Regensburg University Medical Center over a 25-year period (1984 to 2009). Materials and Methods: The study analyzed the frequency of and time to the fracture of clasps, connectors, or denture bases; the occurrence of caries or periodontal lesions; the loss of abutment teeth; and the necessity of maintenance procedures such as relining or treatment of pressure areas. Results: The median follow-up time of 3 years was calculated using the inverse Kaplan-Meier method. The 5-year survival rate (time to renewal) of all CR-RPDs was 96.4%; the 10-year survival rate was 89.8%. Fractures most frequently occurred in clasps (n = 28, 16.1%) followed by major connectors (n = 9, 5.1%) and minor connectors (n = 6, 3.4%). The 5-year event-free rate for clasp fracture was 80.4%; the 10-year event-free rate was 76.9%. Caries lesions on abutment teeth were seen in 31.6% of patients, and 35.6% showed inflammation of the periodontal tissue surrounding the abutment teeth. The 5-year event-free rate for caries was 58.4%; the 10-year rate was 39.6%. A frequent complication was loss of abutment teeth (n = 15), but this complication was not age-dependent. After insertion of their prostheses, one-third of patients (n = 53, 30.5%) showed pressure areas of the mucosa. Significantly more (P < .001) pressure areas were caused by prostheses of the mandible (39.6%) than by those of the maxilla (12.5%). Conclusions: CR-RPDs showed a survival rate of approximately 90% after 10 years of oral service. The predominant complications during oral service were caries lesions, loss of abutment teeth, and fracture of clasps. [ABSTRACT FROM AUTHOR]

Purpose: The influence of resilient support of abutment teeth on the fracture resistance of all-ceramic three-unit fixed partial dentures (FPDs) was tested in this study. Materials and Methods: Three groups (n = 8) of glass-infiltrated, alumina-based, all-ceramic FPDs that were adhesively bonded to human molar teeth were investigated. In control group A, teeth that were rigidly inserted in polymethyl methacrylate (PMMA) resin were used for thermocycling and mechanical loading (TCML), as well as for fracture testing. In group B, TCML was conducted on teeth that had their roots covered with a polyether layer. After TCML, the polyether layer was removed entirely, and the teeth were rigidly fixed in PMMA for fracture testing. In group C, teeth roots remained covered with a polyether layer during TCML as well as during fracture testing. Using a resilient attachment, tooth mobility was determined in axial, buccal, and oral directions. Results: Mean tooth mobility was 76 ± 4 m in the axial direction, 278 ± 41 m in the buccal direction, and 128 ± 17 m in the oral direction. Group C showed the lowest mean fracture strength (polyether during both TCML and fracture testing) of 523 N. For group B (polyether during TCML but not during fracture testing), a fracture strength of 676 N was found, and for control group A (rigidly embedded teeth), it was 919 N. Conclusion: These results confirmed the influence of resilient attachments on the aging process and fracture strength testing of FPDs. Fracture resistance was significantly reduced when this particular interface was used in both TCML and fracture testing. Int J Prosthodont 2011;24:465-468. [ABSTRACT FROM AUTHOR]

This study investigated the fracture resistance of three different zirconia fixed partial dentures (FPDs) with different cementation methods. Forty-eight three-unit FPDs were adhesively bonded (AB) or conventionally cemented (CC). Sixteen glass-infiltrated zirconia FPDs were used as a control. Fracture resistance was determined after aging. The zirconia systems showed no significant different fracture forces with the different bonding methods (CC: Cercon [1,231.5 ± 410.1 N], Ceramill [1,311.3 ± 318.3 N], Vita YZ [1,269.0 ± 317.4 N]; AB: Cercon [1,072.3 ± 516.7 N], Ceramill [1,358.6 ± 176.4 N], Vita YZ [1,270.6 ± 267.6N]) or between the different materials. The control group provided significantly lower fracture strength. Regarding fracture resistance, adhesive bonding or conventional cementation of zirconia FPDs showed no restrictions for posterior application. [ABSTRACT FROM AUTHOR]

Purpose: Denture survival, or the time between the date of a denture's insertion and the date of its renewal for any clinical reason, was assessed in this retrospective study on 353 complete dentures. The procedures required to prolong the useful time of the study sample-relines, repair of denture base fractures, or replacement of lost artificial teeth-were also evaluated. Materials and Methods: All dentures were examined by the authors and were constructed according to a standardized protocol by full-time staff members of the Department of Prosthodontics, Regensburg University Medical Center, between 1984 and 2009. Two subgroups were assigned: 94 patients had one complete denture in each arch (group 1), while 165 patients had one complete denture in either the mandible or the maxilla (group 2). Results: In group 1, the median (75th, 90th percentile) survival time of dentures was 15.8 years in the mandible (15.7, 7.0; 95% confidence interval [CI]: 15.5 to 16.1) and 19.4 years in the maxilla (15.8, 8.7; 95% CI: 14.0 to 24.7). Reline procedures were required most frequently in the maxilla, while 5-year event-free rates were 69.7% for the maxilla and 80.5% for the mandible. Denture base fractures were reported in 5.8% of patients in group 1 and tended to occur more frequently (median: 15.2%) if patients had only one denture (group 2, n = 25 [maxilla: n = 23, mandible: n = 2]). Loss of artificial teeth was a rare complication and found in only 5.8% of patients in group 1 and 10.9% of patients in group 2. During the first 5 years of service, more than 95% of patients in group 1 and 90% of patients in group 2 were 'event free' with regard to loss of artificial teeth. Conclusions: Long-term functional service of complete dentures requires a high number of maintenance procedures, and there is a greater need for interventions in patients wearing only one complete denture (group 2). Int J Prosthodont 2010;23:410-417. [ABSTRACT FROM AUTHOR]

PURPOSE: The aim of this study was to investigate the survival rates and technical failures of removable prostheses (RPs) supported by telescopic double crown (TDC)-retained abutment teeth luted with zinc-phosphate or glass-ionomer cement. MATERIALS AND METHODS: Clinical records of 577 patients (288 women, 289 men) who received 577 TDC-retained RPs supported by 1,807 abutments at the Department of Prosthodontics of the University Hospital Regensburg, Regensburg, Germany, between 1984 and 2007 were analyzed. The 577 prostheses included 200 attached to telescopic crowns with friction fit (FFs), 62 to conical crowns (CCs), and 315 to parallel-sided telescopic crowns with clearance fit (CFs). Survival probabilities were evaluated for the RPs, loss of cementation of the inner copings, secondary caries, and abutment teeth that required endodontic treatment using the Kaplan-Meier method. A Cox regression analysis determined the impact of covariates such as sex, denture location (maxilla/mandible), Eichner classification, number of abutment teeth, and the type of double crown system used. RESULTS: The 10-year survival probability was 98.8% +/- 0.09% for FFs, 92.9% +/- 0.41% for CCs, and 86.6% +/- 0.05% for CFs. During the observation period, loss of cementation was frequently observed (FFs: 32%, CCs: 53.2%, CFs: 21.3%). After 15 years, more than 75% of patients had experienced at least one 'loss of cementation' event. In this respect, zinc-oxide phosphate and glass-ionomer cements did not show any significant difference. CONCLUSION: The long-term successful outcome of the RP experience was not compromised, although numerous clinical visits were required for maintenance. The predominant maintenance procedure was the need for recementation of the inner copings. [ABSTRACT FROM AUTHOR]

Objective: To determine the fracture resistance of resin-bonded fixed partial dentures (RBFPDs) by examining the influence of framework design and abutment mobility. Method and Materials: RBFPD frameworks were made of zirconia (Cercon Base, Degudent) or a nonprecious alloy (reference; Dentitan, Elephant Dental) and veneered with ceramic (Cercon Ceram S, Degudent). The zirconia framework design varied between a 2-retainer RBFPD with 3 different levels of tooth mobility (groups 1 to 3) and a 1-retainer cantilever version with 2 different grades of tooth mobility (groups 4 and 5). To achieve different mobility (rigid, medium, movable), the roots of the teeth were covered with a polyether material of different thicknesses. All RBFPDs were adhesively luted on prepared human teeth (Panavia 21 Ex, Kuraray). The specimens were mechanically (1.2 3 106; 25 N) and thermally (6,000 3 5°C/55°C; 2 minutes per cycle) cycled and finally loaded to failure (universal testing machine 1445, Zwick) at a speed of 1 mm/min. Results: The fracture force of the reference RBFPD (541 N) was significantly higher than that of both cantilever RBFPDs (group 4 = 271 N, group 5 = 104 N) and one 2-retainer group with rigid abutments (group 3 = 150 N). With 2 movable abutments, the fracture force increased to 261 N (group 1) and with mixed movable/rigid teeth to 324 N (group 2). Zirconia RBFPDs showed improved survival with increased tooth mobility, but the framework design showed only a minor influence on loss rate and fracture resistance. Conclusions: Assuming chewing forces in anterior areas between 200 and 300 N, 1- and 2-retainer zirconia RBFPDs may be suitable as minimally invasive provisional alternatives to metal-supported RBFPDs. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of this in vitro study was to examine the fracture strength of metal-free 3-unit adhesive fixed partial dentures (AFPDs) bonded to mandibular incisors. METHOD AND MATERIALS: Extracted human incisors were positioned in pairs in polymethyl methacrylate resin simulating a clinical anterior situation. Their lingual sides were prepared for adhesive retainers with surfaces and finishing lines in enamel. Eight 3-unit AFPDs were made on master casts per material system: Connect/belleGlass (Girrbach), StickNet (StickTech)/Sinfony (3M Espe), and Empress 2 (Ivoclar Vivadent). The dentures were bonded adhesively using the dual-curing system ED Primer/ Panavia F (Kuraray Europe) and aged by thermocycling (6,000 x 5 degrees C/55 degrees C H2O; 2 minutes each cycle) and mechanical loading (1.2 x 10(6) x 20 N with 1.66 Hz) in an artificial oral environment representing a wearing period of 5 years. The fracture strength was determined in a universal testing machine (UTM 1446, Zwick) at a speed of 1 mm/min, applying the load buccoincisally on the pontics. The different forms of failure were described optically. Medians (25th/75th percentiles) of the fracture results were calculated. Statistical analysis was performed using Mann-Whitney U and Kruskal-Wallis tests (P < or = .05). RESULTS: Five StickNet/Sinfony AFPDs and 7 Empress 2 restorations failed in the artificial oral environment. The remaining Empress 2 dentures showed the highest medians of fracture forces (339 [200/506] N) compared to Connect/belleGlass (257 [242/310] N) and StickNet/Sinfony (256 [204/347] N). Statistical comparisons showed no significant differences. CONCLUSION: Only Connect/belleGlass and Empress 2 showed sufficient resistance against mastication [ABSTRACT FROM AUTHOR]

OBJECTIVE: The esthetic application of bleaching materials has gained popularity, with consequences for teeth and restorative materials. The aim of this investigation was to evaluate the influence of different bleaching agents with varying peroxide concentrations on restorative materials. METHOD AND MATERIALS: The color behavior, Vickers hardness, and surface roughness were determined on different restorative materials and bovine enamel. Cylindric samples of two fine hybrid composites, one microfilled composite, one compomer, and one ormocer were bleached for two 2-hour periods with three commercial and three experimental bleaching agents with varying peroxide concentrations. The properties were determined before and after bleaching. As a control, all materials were investigated without bleaching after a 14-day storage. RESULTS: The restorative materials showed maximum changes in Vickers hardness of 44, maximum changes in surface roughness of between 0.2 and 0.7 microm, and a maximum discoloration of deltaE = 6.8. A statistically significant deterioration of hardness, combined with the highest discoloration, was found for the microfilled composite and the compomer. Different bleaching systems showed varying effects on surface roughness. CONCLUSION: Bleaching resulted in a deterioration of the restorative materials, indicated by a decrease of hardness and an increase in surface roughness. Generally, bovine enamel showed significantly higher discoloration compared to the restorative materials. [ABSTRACT FROM AUTHOR]

This study investigated whether metals or resins can replace human teeth in in vitro fracture tes ts of endodontically treated teeth (ETT), as ETT show high heterogeneity and small availability. Eight incisor-shaped roots per group were adhesively restored with fiber-reinforced composite posts, composite core build-ups and Co-Cr-Mo crowns. Specimens we re thermally cycled and mechanically loaded (TCML) and fracture strength was determined . The results vari ed between 0 Nand 348 N. Extracted ETT may show comparable strength and survival during TCML to teeth in situ and therefore are the first choice for in vitro testing. Substitutes show comparable fracture patterns but different fracture values. [ABSTRACT FROM AUTHOR]