Risk factors and multiple failures in posterior resin-bonded bridges in a 5-year multi-practice clinical trial.
OBJECTIVE
A randomized controlled clinical trial was undertaken, to study the influence of some patient- and operator-dependent variables on the survival of posterior resin-bonded bridges (PRBBs) and to assess the survival of replacement' PRBBs. This report contains some of the results of the 5-year analysis.


METHODS
Survival was defined at three levels: (1) complete survival (without any debonding), (2) functional survival (i.e. survival after one loss of retention) and (3) replacement survival (survival of 'replacement' PRBBs, inserted after rebonded bridges suffered a second dislodgement). Potential risk factors were analysed with Cox's proportional hazards model and differences were tested for significance with the Breslow test. Observed effects are expressed as conditional-relative-risk (CRR). Survival of 'replacement' PRBBs was assessed with the Kaplan-Meier method.


RESULTS
Factors showing significant influences on complete survival were: 'location' (highest risk for mandibular PRBBs: CRR = 2.2), 'aetiology' (higher risk in treatment of aplasia: CRR = 2.9), and 'time of existence' (open spaces existing less than 2 years before insertion of PRBB: CRR: 2.0). The factor 'large open spaces in the mandible' was a risk for both complete and functional survival (CCR values 3.1 and 3.5, respectively). The survival of mandibular and maxillary 'replacement' PRBBs after 5 years was 19 +/- 7% and 31 +/- 18%, respectively.


CONCLUSIONS
Risk factors for PRBBs were: 'location', 'aetiology', 'time of existence', 'isolation method' and 'large open spaces in the mandible'. Mandibular 'replacement' PRBBs showed such an unacceptably low survival rate that fabrication is not recommended.
Department of Occlusal Reconstruction and Oral Function, College of Dental Science, Medical Faculty, University of Nijmegen, The Netherlands. n.creugers@dent.kun.nl
N H
NH
Creugers
R J
RJ
De Kanter
C W
CW
Verzijden
M A
MA
Van't Hof
D000293:Adolescent; D000328:Adult; D000368:Aged; D000044:Dental Abutments; D001840:Dental Bonding; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D003781:Denture Retention; D016379:Denture, Partial, Fixed, Resin-Bonded / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000473:pathology; D008297:Male; D008334:Mandible; D008437:Maxilla; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D016733:Rubber Dams; D016019:Survival Analysis; D013997:Time Factors; D016388:Tooth Loss / Q000534:rehabilitation