Study 2: Dentin Abrasion Tables 3 and 4 and Figure 4 show the results of this study. In clinical loading conditions, <strong>FlexCare</strong> resulted in significantly less dentin abrasion (38 µm) than both the Triumph (81 µm) and the manual toothbrush (77 µm). No significant differences were found between the Triumph and the manual toothbrush. Under uniform loading conditions (150 g), <strong>FlexCare</strong> still showed the least abrasion, although the difference with the manual brush did not reach statistical significance. Both Flexcare (39 µm) and the manual brush (51 µm) resulted in significantly less dentin abrasion than the Triumph (81 µm). Study 3: Orthodontic Bracket Strength Table 5 shows the mean strength and standard deviation required to remove an orthodontic bracket from the specimens in each treatment group. Fortyseven specimens <strong>com</strong>pleted the testing; one specimen was excluded because of possible damage during handling. No significant differences between treatments were found. The results of this in vitro study simulating clinical use conditions suggest that toothbrush and toothpaste usage does not <strong>com</strong>promise orthodontic bond strength. Discussion Study 1: Restorative Materials Abrasion The first in vitro study <strong>com</strong>pared the <strong>FlexCare</strong> and a manual toothbrush to determine their effect on changes in surface characteristics of 3 restorative materials (Solidex, EsthetX, and titanium) and bovine enamel. Surface changes were assessed for roughness and gloss. Scratches from brushing with a toothpaste increase roughness and decrease gloss concurrently. To our knowledge, this is the first report on a <strong>com</strong>prehensive evaluation related to power toothbrushes. Increase in roughness and loss in luster of dental materials after prolonged use of oral hygiene procedures appears inevitable, requiring refinishing of restorations at times. In this study, baseline readings resulted from meticulous polishing using alumina, possibly resulting in a smoother polish than would typically be obtained from in-office treatment. Regardless, the question was whether the <strong>Sonicare</strong> <strong>FlexCare</strong> power toothbrush would differ from a manual brush, and the data suggest that when differences were observed, they favored the <strong>FlexCare</strong>. In practice, it may be postulated that over extended periods of time, changes in surface characteristics will level off to a polishing range determined by the toothpaste abrasive and wear resistance of the specific material, regardless of the toothbrush used. Indeed, a preliminary study on Solidex with additional assessments at 1,500, 6,000, and 24,000 brushing strokes showed a nonlinear change and leveling off between 12,000 and 24,000 strokes (data not shown). Nonetheless, this current study suggests that for clinical loading conditions, abrasion with the <strong>FlexCare</strong> progresses slower <strong>com</strong>pared with the manual brush using a higher brushing force, and might, therefore, require less professional repolishing of restorations. Study 2: Dentin Abrasion The second in vitro study <strong>com</strong>pared dentin abrasion in simulated clinical conditions for the <strong>FlexCare</strong> with an oscillating–rotating power toothbrush and a manual toothbrush and showed that the <strong>FlexCare</strong> was significantly less abrasive than the other 2 brushes. Under equal brushing loads, <strong>FlexCare</strong> still resulted in less abrasion than the other brushes. These results are consistent with similar experiments for previous <strong>Sonicare</strong> model, which indicated that <strong>Sonicare</strong> brushes result in significantly less dentin abrasion than manual toothbrushes and oscillating– rotating power toothbrushes. 2-5 Figure 4—Abrasion of dentin samples after 2 years of simulated brushing with toothpaste 90 90 Wear (µm) 60 Wear (µm) 60 30 30 0 <strong>FlexCare</strong> (90 g) Manual (250 g) Triumph (150 g) 0 <strong>FlexCare</strong> Manual Triumph A. Clinically relevant brushing forces Toothbrush B. Equal (150 g) brushing forces Toothbrush 48 Compendium / September 2007 Vol. 28, No. 9 (Suppl 1)
Table 3—Wear of dentin samples after 2 years of simulated brushing with toothpaste using clinically relevant brushing forces Brush Brushing load (g) Sample size Average wear (µm) Standard deviation (µm) Significance (P
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