Effects of different concentrations of carbamide peroxide and bleaching periods on the roughness of dental ceramics

The wide use of dental bleaching treatment has brought concern about the possible effects of hydrogen peroxide on dental tissue and restorative materials. The objective of this study was to evaluate in vitro the effect of nightguard bleaching on the surface roughness of dental ceramics after different periods of bleaching treatment. Fifteen specimens of 5 × 3 × 1 mm were created with three dental ceramics following the manufacturers' instructions: IPS Classic (Ivoclar-Vivadent); IPS d.Sign (Ivoclar-Vivadent); and VMK-95 (Vita). A profilometer was used to evaluate baseline surface roughness (Ra values) of all ceramics by five parallel measurements with five 0.25 mm cut off (Λc) at 0.1 mm/s. Afterwards, all specimens were submitted to 6-h daily bleaching treatments with 10 percent or 16 percent carbamide peroxide (Whiteness- FGM) for 21 days, while control groups from each ceramic system were stored in artificial saliva. The surface roughness of all groups was evaluated after 18 h, 42 h, 84 h, and 126 h of bleaching treatment. The surface roughness of each specimen (n = 5) was based on the mean value of five parallel measurements in each time and all data were submitted to two-way repeated measures ANOVA and Tukey's post-hoc test (α = 0.05). No significant differences in ceramic surface roughness were observed between untreated and bleached ceramic surfaces, regardless of bleaching intervals or bleaching treatments. This study provided evidence that at-home bleaching systems do not cause detrimental effects on surface roughness of dental ceramics.

Complexo vermelho em indivíduos brasileiros periodontalmente doentes e saudáveis / Red complex in subjects with chronic periodontits and periodontal health

O objetivo deste estudo transversal foi avaliar a presença do complexo vermelho em indivíduos com periodontite crônica e indivíduos periodontalmente saudáveis. Foram selecionados 30 indivíduos, sendo 15 periodalmente saudáveis e 15 com periodontite crónica. Os parâmetros clínicos de profundidade de sondagem (PS), nível clínico de inserção (NCI), presença ou ausência de sangramento à sondagem, placa supragengival visível e supuração, foram avaliados em seis sítios por dente.Amostras de placa subgengival foram coletadas de nove sítios mésio-vestibulares, no grupo saudável, e de seis sítios com PS e NIC ≥5 mm e três sítios com PS e NIC ≤4 mm no grupo com periodontite crónica. As amostras foram avaliadas pelo teste Checkerboarad DNA-DNA Hybridizatíonpaïa a presença de Tannerela forsythia, Treponema dentícola e Porphyromonas gingivalis. Diferenças microbiológicas entre os dois grupos foram avaliadas por meio do teste U de MannWhitney. O grupo de indivíduos periodontalmente saudáveis apresentou níveis médios de contagem (x105±DP) de T. forsythia, T.denticola, fg/ng/Vã/fs