EFFECT OF RESTORATIVE PROCEDURES ON THE STRENGTH OF ENDODONTICALLY TREATED MOLARS

Endodontically treated molar teeth are considered susceptible to fract ure because of loss of tooth bulk. This study evaluated the significan ce of retaining intact marginal ridges and selective cusp coverage in preserving tooth stiffness during restoration. Strain gauges were bond ed to four cusps of 36 intact extracted human lower molars. Teeth were loaded mesially and distally in a closed-loop servohydraulic system t o measure stiffness. Endodontic access was followed by mesio-occlusal or mesio-occulusodistal preparation. Teeth were restored with either a malgam (no overlay), amalgam overlay, or gold overlay with partial or complete cusp coverage. Relative stiffness was calculated for all test conditions. Preserving a marginal ridge in molars did not fully conse rve the strength of adjacent cusps; selective cusp coverage reinforced only the capped cusps; full occlusal coverage with gold or amalgam st rengthened all cusps, but gold did so more consistently. It is more im portant to cover cusps than to preserve tooth structure (including a m arginal ridge) in endodontically treated molar teeth.