Effects of occlusal load on cervical lesions.

Toothbrush abrasion has been considered to cause cervical lesions. However, some investigators have proposed that occlusal loading factors direct tensile stresses at the cervical area, resulting in wedge-shaped abfraction defects. The purpose of this study is to investigate the role of axial and non-axial load on the development of cervical lesions. Matched paired premolars, extracted for orthodontic purposes, were used in a custom-fabricated toothbrushing apparatus. A periodontal sulcus width of 0b1 mm with 1 mm gingival recession was simulated with denture base resin. In phase 1, eight matched premolar pairs were subjected to 80 h (1b4 million strokes) of brushing and 300 g of toothbrush force. Toothpaste slurry was applied continuously through the toothbrush. One specimen in each pair was subjected to 250 h and 45 kg of continuous axial load, while the other unloaded tooth served as a negative control. In phase 2, 10 matched premolar pairs were subjected to the same conditions; however, the experimental teeth were subjected to 250 h and 45 kg of intermittent non-axial load, directed at a 45 degrees angle to the buccal cusp. Rubber impressions were made of the cervical lesions, then trimmed, weighed, and compared to determine the amount of tooth material lost. When teeth were loaded axially, there was significantly less tooth material loss (P < 0b02); however, when teeth were loaded non-axially, there was no significant difference (P =0b80) when compared with controls. Optical and scanning electron microscopy did not reveal any significant differences in the morphology between pairs. Our data suggest that the application of occlusal load may not necessarily play a significant role in the progression of cervical tooth wear commonly referred to as abfraction.