Purpose: To evaluate the progression of wear and the effect of wear on subject-perceived and laboratory cleaning efficacy of two oscillating-rotating electric brush heads, Oral-B Precision Clean (PC) and a store brand Easyflex (SB) brush head, after 4, 6, 8 and 13 weeks of use.
Methods: This research consisted of three phases: (1) Subject questionnaires--A crossover, single-blinded study was conducted among healthy adults who were regular users of Oral-B oscillating-rotating electric toothbrushes. Subjects were recruited from a general population and randomized based on age and gender into one of four cohorts reflecting the time period of use for each product: 4, 6, 8 or 13 weeks. After brushing with their first product (either PC or SB) for the designated period of time, subjects completed a questionnaire evaluating the brush head on 17 attributes related to perceived cleaning performance, brush head condition (i.e., durability) and brush head feel (i.e., gentleness). Subjects then used the second test product for the same period of time and completed the same questionnaire. (2) Wear index investigation--At the end of each time period, subjects' worn brush head pairs were evaluated by an independent, blinded investigator to determine the wear index score. (3) Robot testing--To analyze the laboratory cleaning efficacy of worn refills in the laboratory, a representative sample of 12 subject brush head pairs for each of the four cohorts were evaluated (96 brush heads in total). To analyze the laboratory cleaning efficacy for PC at Week 13 with SB at Week 4, a separate set of 20 subjects (40 brush heads in total) were evaluated. A robot was used to brush standard typodonts (Frasaco A3) covered with plaque substitute with the worn brush head for 2 minutes under standardized, controlled conditions simulating human brushing behavior. A 3D laser scan system was used to measure the area still covered with plaque substitute at different dental sites.
Results: Subject questionnaire--267 subjects completed study questionnaires. Statistically significant superior ratings (P < 0.05) were obtained with the PC brush head compared to the SB brush head for virtually all attributes at all four time periods (16/17 attributes for Weeks 4, 6 and 8 and 17/17 at Week 13). Highly significant advantages (P < 0.0001) were seen for 'overall rating', 'overall cleaning' and 'ready to replace brush head' attributes. Wear Index-- A total of 486 brush head samples (243 pairs) were analyzed for wear. At all four time periods, PC brush heads had a statistically significantly lower (P < 0.0005) mean wear index than SB brush heads. Robot Test--136 brush heads were analyzed using a laboratory (robot) test to investigate cleaning efficacy. Directionally higher laboratory cleaning for PC versus SB was observed for all dental sites (35/35) for all time periods. Comparing PC at Week 13 with SB at Week 4 showed statistically significant differences (P < 0.05) in favor of PC for the majority of dental sites and time periods (23/35).