Indirect composite preparation width and depth and tooth fracture resistance.

PURPOSE

To evaluate the influence of preparation width and depth on the fracture resistance of teeth restored with one type of indirect composite restoration.

MATERIALS AND METHODS

Variations of depth and width were superimposed on a preparation of dentin design and dimensions with other variables including tooth size and morphology being controlled. Indirect composite restorations were constructed and placed in accordance with manufacturer's instructions. The restored teeth were subjected to compressive loading with fracture being induced by application of a 4 mm steel rod to the specimens in a universal testing machine, at a cross-head speed of 1 mm/minute.

RESULTS

Preparation depths of 3 to 4 mm were found to be preferable, but when the prevalence of severe tooth fracture was assessed, the shallower preparation depth was found to be indicated. Cavity depths of one-third and one-half bucco-lingual width were evaluated, the fracturing forces for the group with the narrower width being statistically lower.