Impact of Toothbrush Head Configuration and Dentifrice Abrasivity on Non-Carious Cervical Lesions Development In-Vitro

Field: Dentistry (Health Sciences)

Background: Non-carious cervical lesions (NCCLs) result from the loss of tooth structure at the cemento-enamel junction for reasons unrelated to dental caries.1 NCCLs have been attributed to processes of dental abrasion, erosion and/or abfraction.7 In this study, we focused on the effects of excessive toothbrushing abrasion, resulting from the mechanical interaction between the tooth, toothbrush, and toothpaste. Purpose: The aim of this in vitro study was to investigate the effect of toothbrush head configuration and toothpaste abrasivity combinations on the development and progression of simulated NCCLs, evaluated by 3D optical profilometry. Hypotheses: The study hypotheses were: a) the abrasive level of the dentifrice and toothbrush bristle configuration have a significant influence on the initiation and progression of NCCLs independently; and b) the association between the abrasive level and toothbrush head configuration does affect the initiation and the progression of NCCLs. Materials and Methods: A total of 240 extracted human upper first premolars, free of any dental caries, restorations, stains, or enamel and root defects were selected. The teeth were cleaned with a hand periodontal scaler and randomly allocated into 15 groups (n = 16), generated by the association between toothbrushes of different head configurations (ordinary/flat-trimmed, rippled, cross-angled/multileveled/rubber, cross-angled/multileveled/flex head and feathered) and toothpaste abrasivity (low, medium, and high, simulated using different silica abrasives) in a factorial design. The dental specimens were mounted on custom-made acrylic blocks, and their root surfaces were partially covered with acrylic resin to simulate the gingiva, leaving a 2-mm area in length apical to the cemento-enamel junction exposed to toothbrushing. The specimens were brushed with the tested toothbrushes and abrasive slurries for a total of 35,000 and 65,000 double strokes. Specimens were analyzed by optical profilometry at baseline and after each brushing cycle. The outcome variable was dentin volume loss (mm3), calculated by image subtraction. Data were analyzed using mixed-model analysis of variance (ANOVA). Significance of the Results: Oral health maintenance and effective plaque control depend on the combined usage of a toothbrush and a toothpaste. Specific combinations of toothbrush and toothpaste associated with excessive toothbrushing may lead to tooth wear. Results obtained from this study will showed how different combinations of toothbrush head configuration and toothpaste abrasivity affect NCCL development and progression. Results: A significant interaction among the experimental factors (toothbrush type  abrasive level  brushing cycles) was observed (p = 0.05). All toothbrushes caused significantly more tooth wear when associated with the high-abrasivity slurry, as compared to medium- and low-abrasivity slurries. The medium-abrasivity slurry caused significantly more tooth wear than the low-abrasivity slurry. At both testing points and when associated with the low abrasivity slurry, the Feathered toothbrush was the least abrasive. At 35,000 brushing cycles, the flat-trimmed toothbrush was the most abrasive. At 65,000 brushing cycles, the flat-trimmed toothbrush was the most abrasive only when associated with the high-abrasivity slurry, and the multileveled/rubber bristles was the most abrasive when associated with the medium- and high-abrasivity slurries. Overall, 35,000 brushing cycles resulted in significantly less tooth wear than 65,000 brushing cycles. Conclusion: Considering the limitations of this study, it can be suggested that for patients at higher risk of developing NCCLs, ordinary/flat-trimmed toothbrushes are not favorable options. According to the abrasive level of the toothpaste, either feathered or multileveled/flex head may be more suitable to prevent the development of NCCLs.