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OBJECTIVE: To determine the effect of anti-asthmatic inhalers salbutamol and budesonide on the surface microhardness of bovine tooth enamel. MATERIALS AND METHODS: The study was experimental, prospective, longitudinal, and comparative. The sample consisted of permanent mandibular incisors, which were prepared in (n = 90) blocks of dental enamel of size 3 × 3 mm and 2 mm thick, separated into 6 groups of 15 specimens each in sterile bottles properly labeled and contained in artificial saliva at 37°C. Three measurements (baseline, 5 days, and 10 days) were performed after immersion to determine the microhardness using a Vickers microdurometer programmed to apply a load of 100 gm for 15 seconds. RESULTS: It was observed that the enamel surface microhardness decreased after 5 and 10 days, after being in contact with the anti-asthmatic inhalers based on salbutamol and budesonide. In addition, it was evidenced that there is a greater decrease in the superficial microhardness of the enamel when comparing the values at the beginning and after 10 days; likewise, the reduction in the microhardness of enamel exposed to budesonide was greater (120.8 kg/mm2) compared to salbutamol (112.3 kg/mm2) (p<0.001). CONCLUSION: The two anti-asthmatic inhalers studied decreased superficial enamel microhardness, with the budesonide-based inhaler having a greater erosive effect. CLINICAL SIGNIFICANCE: This research allowed us to know the values of the microhardness of the superficial enamel after being exposed to different anti-asthmatic inhalers that are indicated in daily clinical practice. Therefore, it is important to evaluate this microhardness since the use of different inhalers is very prevalent.

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In vitro models are very useful in dentistry, especially to evaluate preventive methods against dental caries. Although they have been used for more than 30 years, specific demineralization models have not been established for primary enamel, which is more prone to demineralization than permanent enamel. This study evaluates porosity changes in primary enamel surface after a demineralization model through a scientifically validated analytical tool. Nine healthy human anterior primary teeth extracted for therapeutic reasons were included in this study, previous informed consent. The samples were randomly assigned to three groups n = 3: G1_2D, G2_4D, and G3_7D. Scanning electron microscopy (SEM) images at ×200 and ×1000 were taken during two stages: before demineralization (BD) and after demineralization (AD). Morphological characterization was observed at ×1000, while porosity (pore count and perimeter) was analyzed by the ImageJ program, using ×200 SEM images previously converted. Several statistical analyses were used to determine differences (p ≤ .05). Morphological characterization AD revealed new pits and cracks on the enamel surface in G1_2D and G2_4D groups. Localized eroded enamel areas were observed in G3_7D. Pore count of enamel surface BD ranged from 64.26 ± 37.62 to 97.93 ± 34.25 and AD ranged from 150.06 ± 64.86 to 256 ± 58.14. AD, G_4D exhibited a decrease in pore perimeter contrary to G_2D and G_7D. Significant differences were observed. Finally, morphological changes were more evident as days of demineralization increased; 7 days of immersion could be employed as an enamel erosive model. The pore count increased after the demineralization model, BD pores perimeter was heterogeneous, and AD varied according to the immersion period. Morphological changes were more evident as days of demineralization increased. Seven days of immersion could be employed as an enamel erosive model. The initial porosity seems to be a determining factor for the final porousness. The pore perimeter of the primary enamel varied according to the immersion period on the demineralization model.

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Superficial stains and irregularities of the enamel are generally what prompt patients to seek dental intervention to improve their smile. These stains or defects may be due to hypoplasia, amelogenesis imperfecta, mineralized white spots, or fluorosis, for which enamel microabrasion is primarily indicated. Enamel microabrasion involves the use of acidic and abrasive agents, such as with 37% phosphoric acid and pumice or 6% hydrochloric acid and silica, applied to the altered enamel surface with mechanical pressure from a rubber cup coupled to a rotatory mandrel of a low-rotation micromotor. If necessary, this treatment can be safely combined with bleaching for better esthetic results. Recent studies show that microabrasion is a conservative treatment when the enamel wear is minimal and clinically imperceptible. The most important factor contributing to the success of enamel microabrasion is the depth of the defect, as deeper, opaque stains, such as those resulting from hypoplasia, cannot be resolved with microabrasion, and require a restorative approach. Surface enamel alterations that result from microabrasion, such as roughness and microhardness, are easily restored by saliva. Clinical studies support the efficacy and longevity of this safe and minimally invasive treatment. The present article presents the clinical and scientific aspects concerning the microabrasion technique, and discusses the indications for and effects of the treatment, including recent works describing microscopic and clinical evaluations.

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The aim of this study was to evaluate the erosion-inhibiting effect of two toothpastes on the development of erosion-like lesions, by a confocal laser scanning microscope (CLSM). Forty human enamel blocks were divided into five groups (n = 8), in accordance to evaluate the GC MI Paste Plus and Oral B with stannous fluoride, applied as slurries and associated with toothbrush. Specimens were submitted to an erosion challenge from citric acid (0.5%, pH = 2.8), for 5 min, six times a day, alternating in artificial saliva immersions. Reference group was not exposed to treatment. Part of specimens (Groups 02 and 03) was exposed twice daily just to slurries, for 2 min, therefore specimens from Groups 04 and 05 were also abraded, for 30 s. The enamel surfaces were morphological characterized using CLSM images, with mineral loss being measured using the resulting 3D images referenced to an un-challenged portion of the sample. Step values were compared using the one-way ANOVA test. CLSM was shown to be a viable, noncontact, and simple technique to characterize eroded surfaces. The statistical difference in the step size was significant between the groups (P = 0.001) and using multiple comparisons a statistically significant protective effect of toothpastes was shown when these were applied as slurries. Although groups submitted to tooth brush showed mineral loss similar to reference control group, due to the damages of abrasion associated.

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Na descolagem de bráquetes ortodônticos pode ocorrer a perda de esmalte na interface adesivo-esmalte. O objetivo deste estudo foi avaliar os possíveis danos à superfície do esmalte com recolagens de bráquetes metálicos e cerâmicos novos por meio da resistência adesiva ao cisalhamento (RAC), da análise do índice de adesivo remanescente (IAR), da avaliação da rugosidade de superfície (RA) e pela análise de microscopia eletrônica (MEV). Foram usados 120 pré-molares, divididos aleatoriamente em 4 grupos de 30 dentes: CS (Controle Saliva); CA (Condicionamento Ácido); M (Metálico) e C (Cerâmico). Foram colados 120 bráquetes metálicos e 120 cerâmicos, para os grupos M e C, em quatro tempos. Os ensaios mecânicos foram realizados em máquina SHIMADZU, na velocidade 0,5 mm/min. Na avaliação da RAC, o ANOVA a dois critérios demonstrou não haver diferenças (p= 0,052) entre os grupos. Na avaliação do IAR, o teste U de Mann-Whitney demonstrou diferença entre os grupos (p< 0,001), onde o grupo cerâmico exibiu escores mais altos que o metálico. Para a rugosidade, o ANOVA a um critério demonstrou que o grupo M apresentou maior RA (p< 0,001). O teste de Tukey demonstrou que os grupos M e C, após o polimento com discos Sof-Lex, exibiram valores de rugosidade inferiores aos demais grupos. Conclui-se que na remoção de bráquetes metálicos ou cerâmicos e da resina remanescente existe maior risco de danos ao esmalte nas recolagens sucessivas. O polimento com discos Sof-Lex promoveu superfície com maior lisura do esmalte.

Debonding of orthodontic brackets may cause enamel surface loss primarily at the adhesive-enamel interface. The purpose of the present study was to evaluate by means of shear bond strength (SBS), adhesive remnant index (ARI), assessment of surface roughness and electron microscope analysis, the possible damages at enamel surface with repeated rebonding of new metallic and ceramic brackets. One hundred and twenty human premolars were randomly divided into 4 groups of 30 premolars each: CS (Saliva Control); CA (Acid Etching); M (Metal); C (Ceramic). For CA group, 4 repeated acid conditionings were performed. One hundred and twenty metallic and ceramic brackets, for groups M and C, were bonded and rebonded respectively at 4 stages. Mechanical trials were obtained with a SHIMADZU testing machine at 0.5 mm/min cross-speed. The SBS results were statistically tested with ANOVA, and no statistically significant differences (p=0.052) were observed. The ARI was evaluated by Mann-Whitney test, which demonstrated that there was a statistically significant difference between metallic and ceramic brackets (p<0.001). The ceramic group exhibited higher statistically significant scores for ARI than the metallic group. The roughness assessment was made with one-way ANOVA, that showed statistically significant differences between groups (p<0.001). Tukey´s test has demonstrated that the M and C groups that were polished with SofLex discs had statistically significant lower roughness values as compared to other groups. Polishing with Sof-lex discs, lead to increased smoothness of enamel surfaces.

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