Effect of a 10% carbamide peroxide on wear resistance of enamel and dentine: In situ study

Department of Restorative Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Journal of dentistry (Impact Factor: 2.75). 02/2009; 37(4):273-8. DOI: 10.1016/j.jdent.2008.12.001
Source: PubMed


This triple-blind, 2x2 crossover in situ study, was undertaken to verify whether the wear resistance of enamel and root dentine would be affected by bleaching with a 10% carbamide peroxide agent and a placebo agent.
Thirty slabs of each substrate (2mm x 3mm x 2mm) were selected for each phase, after flattening and polishing procedures and microhardness test. After a 7-day lead-in period, one specimen of each substrate was randomly bonded on the facial surface of each one of 30 subject's upper second premolars. The volunteers received instructions on how to perform toothbrushing and application of gel in the tray. Fifteen volunteers bleached their maxillary arch with a 10% carbamide peroxide bleaching agent for a 2-week period, while the remainders used a placebo agent. After a 1-week washout period, a new set of enamel and root dentine slabs were bonded to the premolars and volunteers were crossed over to the alternate agent for 14 days. The resistance of enamel and root dentine to wear following bleaching, toothbrushing and intraoral exposure was measured with a profilometer, using reference areas.
For enamel, ANOVA did not demonstrate significant difference between wear provided by placebo and bleaching agent (p=0.3713), but higher wear depth was observed for bleached root dentine (p=0.0346).
While overnight bleaching caused no alteration in wear resistance of enamel, root dentine showed increased tissue loss.

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    • "Most published studies have evaluated the separate effect of PC104-6,8-11,23 and toothpastes24-28 on dental enamel. Few studies have evaluated the combined effect of those two treatments.7,21 Considering that tooth brushing is a daily oral hygiene practice, whether the patient is undergoing bleaching treatment or not, the aim of the present study was to focus only on the combination effect of the bleaching agent with different toothpastes. "
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    ABSTRACT: Background: This in situ study evaluated the roughness and microhardness of enamel bleached with 10% carbamide peroxide (PC10) and brushed with different toothpastes. Materials and Methods: Two groups of volunteers received PC10 and placebo agents for 21 days in two phases in a crossover 2 × 3 study. Fragments of human enamel were distributed among intraoral removable appliances (IRA). Nine fragments, divided into three triplets, were used in each IRA, and these were brushed with toothpastes R (Colgate), W (Colgate Total 12 Whiteness Gel) or BS (Colgate Whitening Oxygen Bubbles Fluoride). Treatments agents were applied for 8 h overnight. After brushing, the volunteers used the IRA for about 16 h/day. After a washout period, new IRAs were distributed and the volunteers were crossed over to the alternate agent for 21 days. Roughness and microhardness were measured before and after each phase. Results: According to the paired Student’s t-test, roughness of enamel increased and microhardness decreased (P < 0.05). According to analysis of variance generalized linear models, only the toothpaste factor was significant (P = 0.037) for roughness. Conclusion: Enamel microhardness and surface roughness are altered when PC10 bleaching is associated with tooth brushing using toothpastes BS, R, and W.
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    • "Erosive challenge provided by the use of this product in relation to control (DW) results in the softening dentin, which, in combination with abrasion, results in pathological wear of this tissue. The detrimental effects of bleaching and abrasion have been previously investigated (Engle et al., 2010; Faraoni-Romano et al., 2009; Sulieman et al., 2004). Considering the high demand for bleaching procedures and increased use of OTC whitening products, it is possible that the association of these factors would advance the dentin loss. "
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    ABSTRACT: The aim of this study was to determine the erosive potential of hydrogen peroxide (HP) containing mouthwash on dentin assessed by Focus variation three-dimensional (3D) microscopy. Twenty dentin slabs were selected and randomly allocated into two groups (n = 10): DW-Distilled water (pH = 7.27) and HP-1.5% (pH = 3.78). Each specimen was cyclically demineralized (4 × 60 s/day, 10 days) with HP or DW and brushed 3×/day (200 g, 150 strokes-toothpaste with 1,450 ppmF as NaF). Between the challenges, the specimens were exposed to artificial saliva. Afterward, dentin loss was analyzed using focus variation 3D microscopy, and the data were submitted to unpaired t-test (α = 0.05). Statistically significant difference was found between the mean wear rate (μm, ±SD) of HP (1.98 ± 0.51) and DW (1.45 ± 0.39). The results suggest that the use of HP-containing mouthwash associated to brushing may increase the risk of tissue loss and focus variation 3D microscopy may be used as a technique for quantifying dental wear. Microsc. Res. Tech., 2013. © 2013 Wiley Periodicals, Inc.
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    • "Due to the highest organic content of dentin when compared with enamel, it has been suggested that dentin is more prone to mineral loss resulting from tooth bleaching. Some studies have evaluated the effect of carbamide peroxide on the dentin surface.30,45,50,51 We found two studies, one in situ50 and the other in vitro30, that evaluated enamel and dentin resistance to abrasion after bleaching with 10% carbamide peroxide. "
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    ABSTRACT: This review investigates erosion and abrasion in dental structures undergoing at- home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled.
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