Biomechanical effects of cervical lesions and restoration on periodontallycompromised teeth

Objective: The purpose of this study was to photoelastically evaluate the e ffects of cervical root lesions and their restoration on stress distributio n in periodontally compromised teeth. Method and materials: Three-dimension al composite photoelastic models of a maxillary first premolar with buccal cervical root lesions were fabricated. Two different lesion configurations, wedge- and shallow saucer-shaped. at 20% alveolar bone height reduction we re tested. A 35% reduction model was given a wedge-shaped lesion. The lesio ns were restored with microfine resin composite. Vertical loads of 7.5 Ibs were applied to the unrestored and restored models at the tip of the buccal cusp and the tip of the lingual cusp, The resulting stresses within the to oth models were monitored and recorded photographically in the field of a c ircular polariscope arrangement. Results: For buccal cusp loading of the un restored models, stress concentrated at the apex of the lesion regardless o f the lesion shape or periodontal support conditions. The highest stress co ncentration was observed around the apex of the wedge-shaped lesion on the 35% reduction model. Restoring the lesions changed stress distribution. Res toration of the lesions resulted in a marked stress reduction at the lesion apex. Stress along the gingival restoration-model interface was characteri stic for the restored situation. The interfacial stress followed the contou r of the restoration most closely for the wedge-shaped lesion on the 20% su pport reduction model. Conclusion: The shape and dimension of the lesion as well as periodontal support status has considerable influence on stress di stribution, especially around the lesion, restored or not restored.