Influence of cavosurface configuration and composite resin type on impact fracture resistance of Class IV restorations
Smith, R.L.; Hood, J.A.; Stokes, A.N.
New Zealand Dental Journal 86(385): 58-61
1990
ISSN/ISBN: 0028-8047 PMID: 2150978 Document Number: 357499
The fracture behaviours of intact maxillary central incisor teeth, and teeth restored by five different composite resins utilising uninstrumented fractured etched margins and bevelled etched margins, were determined by a pendulum impact method. It was established that: 1. Intact teeth fractured in a predictable manner when struck by a pendulum hammer at predetermined points on the labial surfaces close to incisal angles. 2. The impact resistance of teeth with bevelled margin restorations was significantly greater than that of teeth restored using the uninstrumented fractured margins. 3. Differences in impact resistance between intact teeth and teeth restored with bevelled margins were not significant. 4. There was no significant difference in fracture energy between any of the composite resin materials in either the uninstrumented joint or bevelled joint modes. 5. For all restorations placed on uninstrumented margins, the fracture paths were at or near the adhesive interface; no restorations failed cohesively. 6. Fracture paths in the bevelled joint mode were variable, with fracture occurring either entirely in enamel, or entirely in composite resin, or at the interface.