Proliferative response of gingival cells to ultrasonic and/or vibration toothbrushes

Purpose: To evaluate the effects of ultrasonic and/or vibration toothbrushes on cell proliferation and collagen synthesis. Methods: In eight dogs, teeth and gingivae were stimulated once a day as follows: the first quadrant with an ultrasonic toothbrush (1.6 MHz); the second one with a mechanical vibratory toothbrush (141 Hz); and the third one with a toothbrush generating both the ultrasound and the vibration. The fourth quadrant served as a control. Proliferative activity and collagen synthesis of gingival cells were evaluated by assaying the expression of proliferating cell nuclear antigen (PCNA) and procollagen type I C-peptide (PIP), respectively. Results: After 5 weeks, ultrasonic or vibratory toothbrushes increased the numbers of PCNA-positive fibroblasts and PIP-positive fibroblasts. Toothbrushing with a combination of ultrasound and mechanical vibration increased the numbers of PIP-positive fibroblasts, total fibroblasts and vascular endothelial cells to a greater extent than the one with only ultrasound alone. Vibratory toothbrush, but not the ultrasonic one, induced an increase in collagen density without gingival overgrowth.