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.
Creugers
N H
NH
Department of Occlusal Reconstruction and Oral Function, College of Dental Science, Medical Faculty, University of Nijmegen, The Netherlands. n.creugers@dent.kun.nl
De Kanter
R J
RJ
Verzijden
C W
CW
Van't Hof
M A
MA
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