The effect of toothbrush abrasion force on dentine hypersensitivity in-vitro

OBJECTIVES: This study investigated the effect of tooth brushing force on changes in dentine tubule patency in an erosion-toothbrush abrasion model.

METHODS: 60 dentine samples prepared with an artificial smear layer and divided randomly into control (no toothbrush), 100 g, 200 g or 400 g toothbrush groups. They were immersed in 3:1 artificial saliva/NaF 1450 ppm and either brushed (p35 soft tooth brush; 120 strokes) or not brushed. Then samples were subjected to agitated acid challenge (0.3% citric acid pH2.6 for 2 min). Finally, samples were re-brushed. Calibrated software calculated patent dentine tubules that cause DH in confocal microscopy images taken of samples at each stage.

RESULTS: At baseline, mean patent tubules in all samples were 188 (SD54) with no significant inter-group differences. Following first brushing, mean patent tubules decreased using 100 g to 150 (SD32) (p<0.01) and increased using 400 g to 215 (SD45) (p=0.02). Following acid challenge, patent tubules increased to 218 (SD40) in all samples (p<0.01) with no significant inter-group differences. Following further brushing, mean patent tubules decreased using 100 g to 175 (SD72) (p<0.01), but increased with 400 g to 232 (SD52).

CONCLUSIONS: At higher brushing forces (400 g), more tubules were exposed. At lower brushing forces (100 g), tubule patency decreased even post-acidic challenge.

CLINICAL SIGNIFICANCE: It is often recommended to our patients with DH to brush using lighter brushing forces but our understanding of this force on dentine tubule patency is unknown. The management of DH requires lighter brushing forces to reduce the numbers of patent dentine tubules.