Nhj. Creugers et al., RISK-FACTORS AND MULTIPLE FAILURES IN POSTERIOR RESIN-BONDED BRIDGES IN A 5-YEAR MULTIPRACTICE CLINICAL-TRIAL, Journal of dentistry, 26(5-6), 1998, pp. 397-402
Objectives: 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 asses
s the survival of 'replacement' PRBBs. This report contains some of th
e results of the 5-year analysis. Methods: Survival was defined at thr
ee levels: (1)complete survival (without any debonding), (2) functiona
l survival (i.e. survival after one loss of retention) and (3) replace
ment survival (survival of 'replacement' PRBBs, inserted after rebonde
d bridges suffered a second dislodgement). Potential risk factors were
analysed with Cox's proportional hazards model and differences were t
ested for significance with the Breslow test. Observed effects are exp
ressed as conditional-relative-risk (CRR). Survival of 'replacement' P
RBBs was assessed with the Kaplan-Meier method. Results. Factors showi
ng significant influences on complete survival were: 'location' (highe
st 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 f
actor 'large open spaces in the mandible' was a risk for both complete
and functional survival (CCR values 3.1 and 3.5, respectively). The s
urvival 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', 'isolati
on method' and 'large open spaces in the mandible'. Mandibular 'replac
ement' PRBBs showed such an unacceptably low survival rate that fabric
ation is not recommended. (C) 1998 Elsevier Science Ltd. All rights re
served.