Influence of using different bonding systems and composites on the margin integrity and the mechanical properties of selectively excavated teeth in vitro

Abstract

ObjectivesSelective (incomplete) caries excavation reduces the risk of pulpal complications, but might compromise the properties of teeth or restorations. Different restorative approaches might be required after selective instead of complete excavation. We compared margin integrity, micro-leakage and fracture resistance of selectively excavated and differently restored premolars in vitro. MethodsIn 72 extracted human premolars, artificial residual lesions were induced on pulpo-axial walls of standardized cavities. Teeth were restored using one of three bonding systems (OptiBond FL, Clearfil SE Bond, G-aenial Bond) and a fibre-enforced (EverX) or standard hybrid composite resin (Filtek Z250). After thermo-mechanical cycling, groups (n=12) were compared regarding their gingivo-cervical margin integrity (proportion of acceptable margins), microleakage depth, and fracture resistance, with statistical evaluation using generalized linear modelling. ResultsMargin integrity was significantly influenced by the bonding system (p<0.001), but not by the composite (p=0.105). Proportions of acceptable margins were increased in teeth restored with OptiBond FL (median [25th/75th percentiles]: 93 [78/100%]) or Clearfil SE (82 [60/94]%) compared with G-aenial Bond (43 [15/74%]; p<0.05). Neither bonding systems nor composites significantly influenced leakage depth in enamel (p=0.749/0.569) or dentine (p=0.112/0.909). Fracture resistance was significantly influenced by bonding system (p=0.008) and composite (p=0.001), and was higher in teeth restored using OptiBond FL (mean [SD]: 1210 [336]N) compared with Clearfil SE (1007 [208]N) or G-aenial Bond (1023 [281]N, p<0.05), and using EverX (1182 [314]N) instead of Filtek Z250 (979 [228]N; p<0.01). ConclusionsBonding systems which perform well in completely excavated teeth also yielded good results for selectively excavated teeth in vitro. Using fibre-enforced composites to restore selectively teeth increased fracture resistance. Clinical significanceBonding systems which perform well in completely excavated teeth are also suitable for restoring selectively excavated teeth. Using fibre-enforced composites seems suitable for increasing the fracture resistance of selectively excavated teeth and their restorations.