Microwave radiation is effective at disinfecting dental stone surfaces without changing their physical properties.

The aims of this study were to evaluate the effectiveness of different microwave radiation regimens for disinfection of type IV dental stone surfaces and to assess the influence of these regimens on surface roughness and dimensional change following disinfection. Three hundred cylindrical (20 × 2-mm) test specimens were made in type IV stone and divided into subgroups of 20 according to the microorganisms tested (Staphylococcus aureus, Escherichia coli, or Candida albicans) and the 900-W microwave radiation protocol (cycles of 3, 5, or 7 minutes; a positive control; or a negative control). To test physical changes, 80 test specimens were made with the same dimensions except that they had 2 parallel and symmetrical indentations measuring 8 × 4 mm. These specimens were divided into 4 subgroups of 20 each (a subgroup for each radiation time and a negative control). The mean dimensional change and roughness data were analyzed by mixed models for repeated measures and Tukey-Kramer tests. Disinfection was analyzed with descriptive statistics. For E coli and C albicans, all radiation times proved effective at sterilizing the test specimens. For S aureus, sterilization was achieved with 5 and 7 minutes of exposure; however, colonies were observed in 10 Petri dishes (50%) exposed to 3 minutes of microwave radiation. No statistically significant difference in dimensional change or surface roughness was observed for any radiation regimen (P > 0.05).

Finishing and polishing systems influence the roughness and color stability of acrylic and bis-acryl composite resins.

Background: To evaluate the effect of different finishing and polishing systems on the surface roughness and color changes of bis-acryl (Protemp 4 - 3M ESPE- St. Paul, USA; Structur 3 - Voco, Cuxhaven, Germany) and chemically activated acrylic materials (Duralay - Reliance, SP, Brazil). Material and Methods: Specimens (10 x 2 mm) thick were prepared for each material. The specimens were subjected to polishing and finishing procedures with aluminum oxide discs (Diamond Master - FGM, Joinville, Santa Catarina, Brazil) and spiral rubber disks (Sof-Lex - 3M ESPE, Germany). The control did not receive any polishing and finishing procedures. Surface roughness and color measurement values were obtained after the finishing and polishing procedures and immediately after 30 days of storage in water, coffee, and red wine. Data for each material were analyzed by One-Way ANOVA (p<0.05). Results: The polishing with aluminum oxide discs was able to affect the initial surface roughness values of chemically activated acrylic material (p<0.05). After immersion in staining solutions, lower ∆E values were only observed for the bis-acryl composite resins compared to the control group (p<0.05). Conclusions: The finishing and polishing systems influenced the surface roughness and color stability of the materials tested. The chemically activated acrylic resin showed lower surface roughness and higher color stability than the bis-acryl materials. Key words:Acrylic resin, bis-acryl resin, provisional restoration.

Traumatismos dentários em escolares de 12 anos do município de Blumenau, SC, Brasil / Dental trauma in 12-year-old schoolchildren from the city of Blumenau, SC, Brazil

Objetivo: Descrever aspectos do traumatismo dentário relacionados ao gênero, tipo de lesão e localização entre escolares de 12 anos de idade considerando suas seqüelas, os tratamentos realizados e as necessidades de tratamento no município de Blumenau/SC. Método: Estudo exploratório onde foram analisadas as seguintes variáveis: gênero, tipo de lesão e localização. Os exames foram realizados por dois examinadores calibrados (Kappa inter-examinadores = 0,76). Calibração intra-examinadores com concordância de 0,68 para o estudante A e de 0,72 para o estudante B. Foram examinadas 145 crianças com idade de 12 anos de escolas públicas. O contato inicial com as escolas foi via e-mail ou pessoalmente, quando os pesquisadores solicitavam a listagem de alunos com 12 anos e seus respectivos endereços. Após a obtenção desta listagem os alunos eram selecionados a parti r dos setores censitários, identificados pelo Instituto Brasileiro de Geografia e Estatística, previamente sorteados. Resultados: Prevalência de casos de traumatismo: 29,7%, freqüência no gênero masculino 15,2% e feminino 14,5%; tipos de lesão: 91,4% esmalte, 6,9% esmalte e dentina e 1,7% esmalte e escurecimento; elementos afetados: elemento 11 (50%), 21 (34,5%), 12 (6,9%), 22 (5,2%) e 31 (3,4%), condições de tratamentos encontrados: 94,8% sem tratamento e 5,2% restauração; necessidade de tratamento: 1,7%. Conclusão: A prevalência de casos foi moderada com seqüelas de baixa gravidade, sendo o dente mais afetado o 11, seguido do elemento 21.

Objective: To describe aspects of dental trauma related to gender, type of lesion and localizati on in 12-yearold schoolchildren considering its sequelae, treatments accomplished and treatment needs in the city of Blumenau/ SC. Method: This exploratory study analyzed the following variables: gender, type of lesion and localization. The exams were performed by two calibrated examiners (Kappa interexaminer = 0.76): intra-examiner calibration with 0.68 agreement for the student A and 0.72 the student B. A total of 145 12-year-old children attending public schools were examined. The initial contact with the schools was made by e-mail or in person, at which time the researchers requested a list of 12-year-old students and their respective addresses. Thereafter, the students were selected from sectors of census, identified by the Brazilian Institute of Geography and Statistics, which were previously chosen by lot. Results: The prevalence of trauma cases was 29.7%; the frequency in males and females was 15.2% and 14.5, respectively; the types of lesion were: 91.4% enamel, 6.9% enamel and dentin, and 1.7% enamel and darkening; affected teeth: 11 (50%), 21 (34.5%), 12 (6.9%), 22 (5.2%) and 31 (3.4%); treatment conditions: 94.8% no treatment and 5.2% restoration; treatment needs: 1.7%. Conclusion: The prevalence of trauma cases was moderate with low severity sequelae, tooth 11 being the most commonly affected followed by tooth 21.