This study evaluated several means of providing retention for the approximal box in very conservative class 2 preparations (occlusal isthmus width 0.7 mm). Sixty class 2 mesio-occlusal cavities were prepared in sound human maxillary premolar teeth. Four types of retention grooves, 0.3-0.5 mm deep, were prepared at the axiofacial and axiolingual line angles and/or occlusal to those line angles. Specimens were loaded at an angle of 13.5 degrees from vertical in an Instron Universal Testing Machine until the restoration failed. Results indicate that grooves located occlusal to the axiopulpal line angle provided more resistance than conventional grooves (gingival to the axiopulpal line angle) or no grooves. The use of a short retention groove or retention point located occlusal to the axiopulpal line angle, but not extending to the occlusal cavosurface margin, provided greater retention while removing minimal tooth structure.
|Original language||English (US)|
|Number of pages||7|
|State||Published - Mar 1 1992|
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