Effect of Cyclic Loading and Toothbrush Abrasion on Cervical-Lesion Formation

Objectives:   To determine the effect of cyclic loading and toothbrush abrasion with and without abrasive slurries on cervical-lesion formation.  Methods: Extracted human third molars were embedded in acrylic resin.  Teeth were divided into six groups of ten teeth each with the following treatments: 1) control, no treatment, 2) cyclic load in distilled water; 3) brush with distilled water; 4) cyclic load then brush with distilled water; 5) brush with toothpaste slurry; 6) cyclic load then brush with toothpaste slurry. All teeth were scanned prior to testing with a non-contact three-dimensional optical profilometer (ProScan 2000, Scantron) to determine baseline cervical topography.  The specimens were placed in a jig to provide triangulation for realignment of post-treatment specimens to determine volumetric loss.  For groups receiving a dynamic load, the cyclic-loading machine (Sabri) subjected the mounted teeth submerged in distilled water to a cycling force of 10 to 150 N per second (1 Hz) for 1.6 million cycles at a 45-degree angle to the occlusal surface for an equivalent of 4 years of contact for an average patient.   For groups receiving toothbrush abrasion, teeth were brushed in a toothbrush machine (Sabri) for an equivalent of 4 years of brushing with 30,000 strokes at a rate of 1 stroke per minute (1 Hz).   The abrasive slurry contained toothpaste (Colgate Total) and distilled water (9 gm toothpaste per 27 mL water).   The teeth were scanned to determine the volumetric loss of tooth structure.  Data were analyzed with a two-way ANOVA/Tukey’s (alpha=0.05).  Results: A significant difference was found between groups based on brushing (p<0.001) but not on load cycling (p=0.122) with no significant interaction (p=0.173).    Conclusions: Load cycling had no significant effect on cervical tooth loss.  Brushing with toothpaste resulted in significantly greater cervical tooth loss than brushing with water, which was significantly greater than no treatment.

 

	Groups Mean Volumetric Loss   mm3 per mm2 (st dev) Control (no load cycling or brushing) 0.012 (0.005) Load cycled only 0.013 (0.008) Brushed with water 0.066 (0.032) Load cycled; brushed with water 0.069 (0.039)  Brushed with toothpaste 0.121 (0.041) Load cycled; brushed with toothpaste 0.155 (0.039)