***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE The purpose of this study was to evaluate the long-term outcome of In-Ceram Alumina fixed partial dentures ( FPD ) performed in a general dental practice from 1992 to 1996 . MATERIAL S AND METHODS The study was conducted as a retrospective assessment of up to 9 years of patient records and a clinical follow-up examination of patients treated with In-Ceram Alumina FPDs . In 37 patients , 42 FPDs had been inserted during the selected period . After r and omized selection , 16 patients with 18 FPDs were examined clinical ly . The most common restorations comprised two and three units . Cantilever extensions were present on 64 % of the FPDs . Sixty-two percent of the FPDs extended into the posterior region . RESULTS The mean time in function for the 42 FPDs was 76 months ( range 2 to 110 months ) , with 86 % being followed for > 5 years . No adverse effects to either periodontal or pulpal tissues were recorded . The technical quality was very good , and patient satisfaction very high . Five FPDs fractured during the observation period , result ing in a total failure rate of 12 % . Two of these FPDs fractured as a consequence of external trauma . Excluding these , the total survival rate during the observation period was 93 % . Cumulative survival rate according to life table analysis was 93 % after 5 years and 83 % after 10 years . CONCLUSION The results suggest that the In-Ceram Alumina short-span FPD is a viable prosthetic alternative PURPOSE The aim of this prospect i ve study was to evaluate the clinical efficacy and long-term survival rate of  three-unit fixed partial dentures ( FPDs ) made from lithium disilicate-based core ceramic . MATERIAL S AND METHODS Twenty-one three-unit FPDs were placed in 19 patients to replace single lost teeth in the esthetic area , following a study protocol that took clinical , esthetic , and radiologic aspects into consideration . Each case was review ed at 1 week following placement , at 6 months , and then annually for 10 years . Statistical analysis was performed using Kaplan-Meier survival analysis . RESULTS Out of the 19 patients , 14.3 % presented reversible postoperative sensitivity . Recession was observed in 24 % of dental posts , and 7.1 % presented marginal discoloration . Treatment did not increase either Bleeding or Plaque Index scores at prepared teeth ; secondary caries did not appear either . The restorations ' survival rate at the 10-year follow-up was 71.4 % ; six FPDs had fractured and one debonded . CONCLUSIONS Fracture failure rate was 28.6 % after 10 years ; a high percentage corresponded to connector fractures and occurred during the first 5 years . Lithium disilicate glass-ceramic FPDs present a higher risk of fracture than st and ard therapies ( metal-ceramic ) or other more recently developed ceramic material s. The prognosis for survival improves for Class I occlusion and nonparafunctional patients STATEMENT OF PROBLEM Although the favorable mechanical properties of zirconium oxide-based ceramics have increased the acceptance of fixed dental prostheses for use in the posterior regions of the mouth in recent years , there are few clinical studies documenting the longevity of these restorations . Furthermore , certain complications must be resolved before the material is used more extensively . PURPOSE The purpose of this r and omized prospect i ve study was to evaluate the clinical performance of zirconia ( Lava ) 3-unit posterior fixed dental prostheses . MATERIAL AND METHODS Twenty 3-unit fixed dental prostheses were placed in 17 participants to replace a second premolar or a first molar . Eleven were placed in the maxilla and 9 in the m and ible . All abutment teeth were prepared with a chamfer finish line of 0.8 to 1 mm , and frameworks were prepared with the Lava system . Restorations were cemented with a resin cement . Two calibrated examiners independently evaluated the fixed dental prostheses 1 week ( baseline ) and 1 , 2 , and 3 years after placement with the California Dental Association quality evaluation system . The periodontal parameters : the gingival index , plaque index , margin index , and the probing depths of abutment teeth and contralateral teeth were assessed . Data were analyzed by using descriptive statistics and the Wilcoxon signed-rank test ( α=.05 ) . RESULTS All fixed dental prostheses were rated satisfactory after 3 years , and no fracture of the framework was observed during the observation period . One fixed dental prostheses was lost because of a biological complication at the 3-year examination , and a small degree of chipping of the veneering ceramic was observed in 2 participants . No significant differences among the periodontal parameters of the test and control teeth were observed except for the margin index . CONCLUSIONS The results of a 3-year evaluation suggest that posterior zirconia 3-unit fixed dental prostheses are a reliable treatment This study aim ed to evaluate three- and four-unit posterior fixed partial dentures ( FPDs ) with zirconia frameworks after 5 years of function . Of the initial 30 subjects , 25 patients with 25 FPDs were examined after a mean follow-up period of 62.1 months . Five patients were not available for recall visits . Two FPDs failed before the 60-month evaluation because of framework fracture or delamination of the veneering ceramic after endodontic treatment . The 5-year survival rate was 92 % . Based on these results , it can be suggested that zirconia frameworks have sufficient mechanical requirements for use in the stress-bearing posterior region . Major fracture of the ceramic veneer could be related to inadequate framework design or bruxism The aim of this r and omized controlled trial was to evaluate the clinical performance of lithium disilicate fixed partial dentures ( FPDs ) .  Eighteen patients received lithium disilicate FPDs ( study group ) , and 19 patients received porcelain-fused-to-metal FPDs ( control ) .  After 6 years , the survival probabilities were found to be 63 % in the study group and 95 % in the control group ( log-rank test , P = .028 ) . The data suggest that strict conditions should be considered before the use of lithium disilicate glass-ceramic for FPDs OBJECTIVES The purpose of this prospect i ve study was to evaluate the clinical outcome of  crown-retained fixed dental prostheses ( FDPs ) made  from a lithium-disilicate glass-ceramic ( IPS e.max Press , Ivoclar-Vivadent ) . METHODS Thirty-six three-unit FDPs were placed in 28 patients . The FDPs replaced teeth in the anterior ( 16 % ) and posterior ( 84 % ) regions . All teeth were prepared following a st and ardized protocol . The size of the proximal connector of the FDPs was 12 mm2 ( anterior ) or 16 mm2 ( posterior ) . FDPs were cemented either with glass-ionomer cement ( n=19 ) or composite resin ( n=17 ) . The following parameters were evaluated at baseline , 6 months after cementation and then annually ( at abutment and contralateral teeth ) : probing pocket depth , plaque index , bleeding on probing , and tooth vitality . RESULTS Three FDPs were defined as drop-out . The mean observation period of the remaining 33 FDPs was 86 months ( range : 67 - 98 months ) : two FDPs in two patients had to be replaced ( 6 % ) because of fractures . The 8-year survival rate according to Kaplan-Meier was 93 % . In addition , chipping of the veneering material was found in two FDPs ( 6 % ) . Two abutments ( 3 % ) of two restorations had to be treated endodontically ; and two FDPs ( 6 % ) lost retention and had to be recemented . These complications did not affect the function of the involved restorations clinical ly . There were no significant differences between the periodontal parameters of the test and control teeth . SIGNIFICANCE Short-span crown-retained three-unit FDPs made from lithium-disilicate glass-ceramic can be used clinical ly irrespective of an adhesive or conventional cementation PURPOSE The aim of this prospect i ve clinical cohort study was to determine the success rate of 3- to 5-unit zirconia frameworks for  posterior fixed partial dentures ( FPDs ) after 5 years of clinical observation . MATERIAL S AND METHODS Forty-five patients who needed at least 1 FPD to replace 1 to 3 posterior teeth were included in the study . Fifty-seven 3- to 5-unit FPDs with zirconia frameworks were cemented with 1 of 2 resin cements ( Variolink or Panavia TC ) . The following parameters were evaluated at baseline , after 6 months , and 1 to 5 years after cementation at test ( abutments ) and control ( contralateral ) teeth : probing pocket depth , probing attachment level , Plaque Index , bleeding on probing , and tooth vitality . Intraoral radiographs of the FPDs were taken . Statistical analysis was performed using descriptive statistics , Kaplan-Meier survival analysis , and the McNemar test . RESULTS Twenty-seven patients with 33 zirconia FPDs were examined after a mean observation period of 53.4 + /- 13 months . Eleven patients with 17 FPDs were lost to follow-up . After the 3-year recall visit , 7 FPDs in 7 patients were replaced because they were not clinical ly acceptable due to biologic or technical complications . After 5 years of clinical observation , 12 FPDs in 12 patients had to be replaced . One 5-unit FPD fractured as a result of trauma after 38 months . The success rate of the zirconia frameworks was 97.8 % ; however , the survival rate was 73.9 % due to other complications . Secondary caries was found in 21.7 % of the FPDs , and chipping of the veneering ceramic in 15.2 % . There were no significant differences between the periodontal parameters of the test and control teeth . CONCLUSIONS Zirconia offers sufficient stability as a framework material for 3- and 4-unit posterior FPDs . The fit of the frameworks and veneering ceramics , however , should be improved OBJECTIVE The aim of this prospect i ve clinical study was to evaluate the survival rates of IPS Empress 2 ( Ivoclar Vivadent ) all-ceramic crowns and fixed partial dentures ( FPDs )  after an observation period of up to 5 years . METHOD AND MATERIAL S Forty-three patients ( 19 women and 24 men ) were included in this study . The patients were treated with a total of 58  adhesive bonded IPS Empress 2 restorations .  A total of 27 single crowns  were placed on molars and premolars , and 31 three-unit FPDs were placed in the anterior and premolar regions . Clinical follow-up examinations took place at 6 , 12 , 24 , 36 , 48 , and 60 months after insertion . Statistical analysis of the data was calculated using the Kaplan-Meier method . RESULTS Results of the 50-month analysis ( interquartile range , 33 to 61 months ) showed that the survival rate was 100 % for crowns and 70 % for FPDs . Six failures that occurred exclusively in the three-unit FPDs were observed . Framework fractures were recorded in three FPD units where the connector dimensions did not meet the manufacturer specifications . Only one FPD exhibited an irreparable partial veneer fracture , and 2 FPDs showed evidence of biologic failures . The accuracy of fit and esthetic parameters were clinical ly satisfactory for crowns and FPDs . CONCLUSION The results of this 5-year clinical evaluation suggest that IPS Empress 2 ceramic is an appropriate material for the fabrication of single crowns . Because of the reduced survival rates , strict conditions should be considered before the use of IPS Empress 2 material for the fabrication of three-unit FPDs PURPOSE The aim of this prospect i ve study was to evaluate the clinical performance of zirconia-based posterior four-unit fixed dental prostheses ( FDPs )  after 4 years of clinical observation . MATERIAL S AND METHODS Between 2006 and 2010 , 10 patients ( 5 women , 5 men ; mean age : 52.8 years ) received 17 posterior four-unit FDPs .  Two calibrated examiners evaluated the FDPs independently 1 week ( baseline ) , 6 months , and 1 , 2 , 3 , and 4 years after placement using California Dental Association ( CDA ) criteria . Periodontal status was assessed on both the abutment and contralateral control teeth using Plaque Index , Gingival Index , probing attachment level , and Margin Index parameters . Statistical analysis was performed using descriptive statistics and the Wilcoxon signed-rank test . RESULTS Three restorations were lost because of fractures at their distal connectors after a mean clinical service of 25.3 months , and one abutment tooth was extracted because of vertical root fracture 23 months after cementation . Three FDPs presented chipping of a moderate size 1 week before framework fracture , and minor chipping was observed in 2 other FDPs 1 week and 36 months after cementation . After 4 years of clinical service , the cumulative survival rate of the posterior four-unit FDPs was 76.5 % . No caries lesions were detected on the abutment teeth . The remaining restorations were judged to be satisfactory according to the CDA criteria . Periodontal parameters 
    Output:
    
A significantly higher incidence of caries in abutment teeth was observed for densely sintered zirconia FDPs compared to metal-ceramic FDPs .
Survival rates of all types of all-ceramic FDPs were lower than those reported for metal-ceramic FDPs .
The incidence of framework fractures was significantly higher for reinforced glass ceramic FDPs and infiltrated glass ceramic FDPs , and the incidence for ceramic fractures and loss of retention was significantly higher for densely sintered zirconia FDPs compared to metal-ceramic FDPs