Dentistry School Theses and Dissertations

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Browsing Dentistry School Theses and Dissertations by Subject "Abrasion"

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    The Impact of Mouthrinses on the Efficacy of Fluoride Dentifrices in Preventing Enamel and Dentin Erosion/ Abrasion
    (2018) Albeshir, Ebtehal; Lippert, Frank; Cook, Norman B.; Hara, Anderson
    Objective: Toothbrushing with fluoride toothpaste followed by rinsing with mouthwash is a routine procedure to maintain good oral hygiene. It is unknown to what extent these rinses can modulate the effect of fluoride in its ability to prevent erosion/abrasion.The aim of this in-vitro study was to investigate and compare the impact of chlorhexidine (CHX), essential oils (EO) and cetylpyridinium chloride (CPC) mouthrinses on erosive tooth wear protection afforded by conventional fluoride toothpastes. Materials and Methods: The following experimental factors were considered: five rinses: CHX, EO, CPC, a fluoride rinse, and deionized water, two fluoride toothpastes: stannous fluoride (SnF2) or sodium fluoride (NaF) and two models: (erosion/ erosion+abrasion). Slabs of bovine enamel and dentin were prepared and embedded in resin blocks and generated 10 enamel and dentin testing groups (n = 8). UPVC tapes were placed on the sides of each slab leaving 1mm area exposed in the center. The blocks were subjected to a five-day cycling model. Then, the blocks were placed in a brushing machine and exposed to fluoride toothpaste slurry (one side was brushed and the other wasn’t). The blocks were then exposed to rinse treatments. Artificial saliva was used to remineralize the specimens after erosions and treatment challenges, and as storage media. After the fifth day of cycling, surface loss (in micrometers) was determined by profilometer. Data were analyzed using ANOVA (α = 0.05). Results: There was no interaction among the three factors (type of toothpaste, mouthrinse and abrasion or not (dentin p = 0.0520, enamel p = 0.4720). There were no significant two-way interactions as SL was only affected by toothpaste and mouthrinse. NaF caused less SL than SnF2 (4.60 vs. 5.83 μm; p < 0.0001) in dentin, whereas the opposite was found in enamel (5.20 vs. 3.56 μm; p < 0.0001). Toothbrushing abrasion caused comparatively more SL in enamel (6.53 vs. 2.23 μm; p < 0.0001) than in dentin (6.06 vs. 4.38 μm; p < 0.0001). None of the tested mouthrinses affected SL. Conclusion: Commonly used mouthrinses containing antimicrobial agents or additional fluoride, do not impair the erosion/abrasion protection afforded by fluoride toothpastes. Tested SnF2 dentifrice offered greater protection against enamel surface loss and NaF dentifrices showed more protection for the dentin surface. Clinical relevance: The understanding of the interaction between commonly used rinses and fluoride dentifrices will help dentists provide better recommendations to patients with erosive lesions.
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    Impact of Toothbrush Head Configuration and Dentifrice Abrasivity on Non-Carious Cervical Lesions Development In-Vitro
    (2022) Alzahrani, Lina; Hara, Anderson T.; Lippert, Frank; Al Dehailan, Laila
    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.