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The aim of the study was to measure the degree of dentine surface roughness caused by five distinct lasers used to treat dentine hypersensitivity, as well as to evaluate the subsequent bacterial colonization on these irradiated surfaces. Sixty human maxillary premolar teeth without caries or restoration which were extracted for periodontal reasons were used in this study. Five different types of lasers were applied to the root dentin surface. Tested samples were divided into six groups of 10 samples each; control, diode (810 nm), diode (980 nm), Nd: YAG, Er: YAG, and Er, Cr: YSGG laser groups. The arithmetic mean of the surface roughness values (Ra) and the average roughness over a measurement area (Sa) were measured pre- and post-application using any of the laser types. Swab samples were then collected from the dentin surface. Following a 24-hour incubation period at 37 °C, the colony forming units were counted using a stereoscope. The results demonstrated a statistically significant difference in the surface roughness values pre- and post-application (Ra and Sa, respectively) in the Er, Cr: YSGG laser group (p = 0.037,p = 0.007). No significant difference was observed in the other groups (p > 0.05). There was no statistically significant difference in the number of bacterial colonies observed between the test and control groups. Diode and Nd: YAG lasers showed either a decrease or no change in surface roughness; however, the hard tissue lasers (Er: YAG, Er, Cr: YSGG) showed an increase. The Er: YAG and Nd: YAG laser groups exhibited decreased bacterial adhesion compared to the other groups.

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The aims of this study were evaluate cytotoxicity, genotoxicity, antimicrobial activity of desensitizing toothpastes compared to a common one and the surface roughness of tooth enamel submitted to brushing with these toothpastes. Samples of three desensitizing toothpastes (Colgate Sensitive, Sensodyne and Oral B Sensitive) and common toothpaste (Colgate) were placed in contact with gingival human fibroblasts. Cytotoxicity and genotoxocity were measured by MTT assay and micronucleus test. Antimicrobial activity of the toothpastes extracts against C. albicans, S. mutans and S. aureus were assessed. For surface roughness evaluation, bovine teeth were submitted to 10.000 brushing cycles. The results were analyzed statically using Mann-Whitney U, ANOVA and Z tests (p<0.05). All toothpastes caused cytotoxic effect to the cells (p<0.05), except Colgate Sensitive. The toothpastes did not increase the number of micronuclei compared to the untreated control group. Colgate eliminated all the evaluated microorganisms at lower concentrations compared to Colgate Sensitive and Oral B Sensitive, which were not able to eliminate S. aureus. Sensodyne did not reach the minimum microbicidal concentration. The surface roughness of tooth enamel increased after brushing with Colgate Sensitive and Oral B Sensitive, however the comparison between groups showed no difference on the enamel surface roughness presented by desensitizing toothpastes when compared with the common one (p>0.05). Based on these results, we can conclude that although none toothpaste has induced genotoxicity, Colgate Sensitive was also not cytotoxic. Colgate was the most effective against the microorganisms, and there were no differences on the enamel surface roughness between the groups.

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Abstract The aims of this study were evaluate cytotoxicity, genotoxicity, antimicrobial activity of desensitizing toothpastes compared to a common one and the surface roughness of tooth enamel submitted to brushing with these toothpastes. Samples of three desensitizing toothpastes (Colgate Sensitive, Sensodyne and Oral B Sensitive) and common toothpaste (Colgate) were placed in contact with gingival human fibroblasts. Cytotoxicity and genotoxocity were measured by MTT assay and micronucleus test. Antimicrobial activity of the toothpastes extracts against C. albicans, S. mutans and S. aureus were assessed. For surface roughness evaluation, bovine teeth were submitted to 10.000 brushing cycles. The results were analyzed statically using Mann-Whitney U, ANOVA and Z tests (p<0.05). All toothpastes caused cytotoxic effect to the cells (p<0.05), except Colgate Sensitive. The toothpastes did not increase the number of micronuclei compared to the untreated control group. Colgate eliminated all the evaluated microorganisms at lower concentrations compared to Colgate Sensitive and Oral B Sensitive, which were not able to eliminate S. aureus. Sensodyne did not reach the minimum microbicidal concentration. The surface roughness of tooth enamel increased after brushing with Colgate Sensitive and Oral B Sensitive, however the comparison between groups showed no difference on the enamel surface roughness presented by desensitizing toothpastes when compared with the common one (p>0.05). Based on these results, we can conclude that although none toothpaste has induced genotoxicity, Colgate Sensitive was also not cytotoxic. Colgate was the most effective against the microorganisms, and there were no differences on the enamel surface roughness between the groups.

Resumo Os objetivos desse estudo foram avaliar a citotoxicidade, genotoxicidade, atividade antimicrobiana de dentifrícios dessensibilizantes em comparação com um comum e também a rugosidade superficial do esmalte dentário submetido à escovação com esses dentifrícios. Amostras de três dentifrícios dessensibilizantes (Colgate Sensitive, Sensodyne e Oral B Sensitive) e um dentifrício comum (Colgate) foram colocadas em contato com fibroblastos gengivais humanos e a citotoxicidade e genotoxidade foram mensuradas pelo ensaio MTT e teste do micronúcleo. A atividade antimicrobiana dos extratos dos dentifrícios contra C. albicans, S. mutans e S. aureus foi determinada. Para a avaliação da rugosidade superficial, espécimes de dentes bovinos foram submetidas à 10.000 ciclos de escovação. Os resultados foram analisados estatisticamente usando os testes Mann-Whitney U, ANOVA e Teste Z (P<0,05). Todos os dentifrícios causaram efeito citotóxico às células (P<0,05), exceto o Colgate Sensitive. Os dentifrícios não aumentaram o número de micronúcleos em comparação com o grupo não tratado. O Colgate foi capaz de eliminar todos os microorganismos avaliados em concentrações mais baixas em comparação com Colgate Sensitive e Oral B Sensitive, que não foram capazes de eliminar os S. aureus. O Sensodyne não atingiu a concentração microbicida mínima para qualquer microorganismo. A rugosidade superficial do esmalte dentário aumentou após a escovação com Colgate Sensitive e Oral B Sensitive, porém a comparação entre os grupos não mostrou diferença na rugosidade superficial do esmalte apresentada por dentifrícios dessensibilizantes quando comparados ao comum (p>0,05). Com base nesses resultados, podemos concluir que, embora nenhum dentifrício tenha induzido genotoxicidade, o Colgate Sensitive também não foi citotóxico. O Colgate foi o mais eficaz contra os microorganismos, e não houve diferença na rugosidade superficial do esmalte entre os grupos.

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BACKGROUND: The most common problems for a patient with molar incisor hypomineralization (MIH) are the collapse of enamel and cavitations, loss of fillings, and secondary caries, but most of all, severe hypersensitivity. OBJECTIVE: The aim of this paper was therefore to histologically study possible bacterial invasion of dentinal tubules beneath apparently intact, but hypomineralized enamel in permanent molars with MIH. MATERIAL AND METHODS: Five extracted permanent first molars diagnosed with MIH were fixated, demineralized, and sagittally serially sectioned in a bucco-lingual direction in a microtome with a thickness of 4-5 microm. Sections were stained with a modified Brown and Benn staining for bacteria, unstained sections were analysed in field emission SEM. RESULTS: Stained sections from the cuspal areas, below the hypomineralized enamel, the staining indicated the presence of bacteria in the dentinal tubules. The HTX staining showed that the pulp in sections without any findings was normal and free from bacteria or infiltrates from inflammatory cells. In sections where bacteria were found in the cuspal areas or deeper in the dentin, a zone of reparative dentin was found, and in sections from one tooth, the coronal pulp showed an inflammatory reaction with inflammatory cells. In sections adjacent to those without any bacterial staining, the SEM analyses revealed empty dentinal tubules without any odontoblast processes or signs of bacteria. When odontoblast processes were found, the dentinal tubules were filled with bacteria located on the surface of the odontoblast processes. In some areas, a large number of tubules were found with bacteria. No bacteria were found close to the pulp. The odontoblast processes appeared larger in areas where bacteria were found. CONCLUSIONS: The presence of bacteria in the dentinal tubules and inflammatory reactions in the pulp indicate that oral bacteria may penetrate through the hypomineralized enamel into the dentin, thus possibly contribute to hypersensitivity of teeth with MIH.

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The prevention of degeneration and necrosis of the endodont is one of the main goals of dental treatment. Kerschbaum and Voss (1979, 1981) described that 15% of teeth showed negative results to sensitivity testing 10 years after crown preparation. Pulpal responses to dental treatment depend on many factors including thermal injury, transsection of the odontoblastic process, vibration, desiccation of dentin, pulp exposure, smear layer, remaining dentin thickness and used materials. The knowledge concerning endodontic reactions in short and medium term observation is mainly based on research by Klötzer and Langeland. Histological assessment of reactions is a well accepted method for biocompatibility testing (i.e. ISO/TR 7405). It is consistent to apply its principles to the evaluation of endodontic reactions of teeth with long term restorations. As pulpal injury is furthermore due to microleakage between filling material and the wall of the cavity the analysis of infected dentin tubules seems to be important. A consideration of the location of the tubules and of the severity of the invasion is necessary. Using a classification (grade 1-6) comprising the parameters of degenerative and regenerative reactions and bacterial invasion, 24 teeth restored with different types of fixed prosthodontic restorations were investigated. The restorations were between 0-6, 7-12 and 13-18 years in situ. Serial sections (5 microns) were stained with haematoxylin-eosin, azan, according to Goldner and J. Hopkins. 22 of 24 teeth showed typical degenerative reactions. Negative sensitivity testing occurred in teeth with no pain and no or partial necrosis. The histobacteriological assessment showed bacterial invasion of the dentin tubules of 21 teeth. From this investigation it was concluded that the proposed classification shows sufficient sensitivity for the evaluation of progressive endodontic changes of long-term restored teeth. Furthermore it was shown that bacterial invasion must be considered as a possible co-factor for the described degenerative character of the pulpal tissue.

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