Assessment of multispecies biofilm growth on root canal dentin under different radiation therapy regimens.

OBJECTIVES: To assess the growth of a multispecies biofilm on root canal dentin under different radiotherapy regimens. MATERIALS AND METHODS: Sixty-three human root dentin cylinders were distributed into six groups. In three groups, no biofilm was formed (n = 3): NoRT) non-irradiated dentin; RT55) 55 Gy; and RT70) 70 Gy. In the other three groups (n = 18), a 21-day multispecies biofilm (Enterococcus faecalis, Streptococcus mutans, and Candida albicans) was formed in the canal: NoRT + Bio) non-irradiated + biofilm; RT55 + Bio) 55 Gy + biofilm; and RT70 + Bio) 70 Gy + biofilm. The biofilm was quantified (CFUs/mL). Biofilm microstructure was assessed under SEM. Microbial penetration into dentinal tubules was assessed under CLSM. For the biofilm biomass and dentin microhardness pre- and after biofilm growth assessments, 45 bovine dentin specimens were distributed into three groups (n = 15): NoRT) non-irradiated + biofilm; RT55 + Bio) 55 Gy + biofilm; and RT70 + Bio) 70 Gy + biofilm. RESULTS: Irradiated specimens (70 Gy) had higher quantity of microorganisms than non-irradiated (p = .010). There was gradual increase in biofilm biomass from non-irradiated to 55 Gy and 70 Gy (p < .001). Irradiated specimens had greater reduction in microhardness after biofilm growth. Irradiated dentin led to the growth of a more complex and irregular biofilm. There was microbial penetration into the dentinal tubules, regardless of the radiation regimen. CONCLUSION: Radiotherapy increased the number of microorganisms and biofilm biomass and reduced dentin microhardness. Microbial penetration into dentinal tubules was noticeable. CLINICAL RELEVANCE: Cumulative and potentially irreversible side effects of radiotherapy affect biofilm growth on root dentin. These changes could compromise the success of endodontic treatment in oncological patients undergoing head and neck radiotherapy.

The influence of smoking on the effectiveness of at-home bleaching: A prospective clinical study.

OBJECTIVES: To evaluate the effect of smoking on tooth whitening and color change after at-home bleaching. MATERIALS AND METHODS: This prospective clinical study evaluated two groups of participants: NS-non-smokers (n = 24) and S-smokers (n = 16). All subjects were treated with at-home bleaching using 22% carbamide peroxide (CP) for 1 h/day for 14 days. Color coordinates (L*-luminosity, a*-red-green axis and b*-yellow-blue axis) were obtained before bleaching (D0-baseline), 1 day (D1), 15 days (D15), and 1 month (D30) after bleaching. The whiteness index (WID ) and CIEDE2000 color differences (ΔE00 ) were calculated for S and NS. Color changes between S and NS subjects for specific teeth (CI-Central Incisors, LI-Lateral Incisors, and C-Canines) were analyzed using the Mann-Whitney test (α = 0.05). RESULTS: There was no significant difference in WID between S and NS subjects at baseline. NS participants showed higher WID than S at D1, D15, and D30 (p < 0.05). NS showed higher ΔWID for CI and C between D0 and the other evaluation times (D1, D15, and D30) compared to S. Smokers showed higher darkening of CI than NS in ΔWID D30-D1 (p < 0.05). Color changes showed similar overall behavior for ΔWID . For all evaluation times, ΔWID and ΔE00 values were below the corresponding acceptability thresholds. CONCLUSION: At-home bleaching was effective on smokers and nonsmokers. Smoking negatively affected color stability after bleaching. ΔE00 and ΔWID were acceptable for both groups. CLINICAL SIGNIFICANCE: Although smoking negatively affected color stability after bleaching, the observed changes were clinically acceptable.

Influence of smoking on oral cells genotoxicity after at-home bleaching using 22% carbamide peroxide: a cohort study.

OBJECTIVE: This study evaluated the influence of smoking on the oral cells genotoxicity before and after at-home bleaching using 22% carbamide peroxide (CP). MATERIALS AND METHODS: This is a prospective observational analytics cohort study which evaluated nonsmokers (NS; n = 24) and smokers (S; n = 16) patients. At-home bleaching was performed using 22% CP gel in individual trays for 1 h per day for 14 days in both groups. Scrapped cells from marginal gums were collected before the bleaching treatment (D0-baseline) and 1 day (D1), 15 days (D15), and 1 month (D30) after its finishing. Cells were stained with Giemsa 10%, and the micronucleus (MN) and metanuclear alterations (MA) were counted by a trained operator in 1000 cells per patient. The collections and data analysis occurred blindly. Data was analyzed by Kruskal-Wallis, Dunn, and Mann-Whitney test (α = 0.05). RESULTS: MN frequency was not influenced by smoking or bleaching. An increase of MA was observed between D0 and D30 for both groups (p < 0.001); however, no statistical difference was found between NS and S (p > 0.05) in the evaluation times. CONCLUSION: Smoking associated with 22% carbamide peroxide gel for at-home bleaching does not show genotoxic potential analyzed by the MN counts. However, a significant increase of MA was found for smokers and nonsmokers. CLINICAL RELEVANCE: Despite of the increase in MA, smoking associated with 22% CP peroxide at-home bleaching showed no important genotoxic potential (MN) for oral cells. Therefore, at-home bleaching treatment is safe for nonsmokers and smokers even with a high carbamide peroxide concentration of 22%.

Sistemas adesivos universais ­ há 10 anos no Brasil: revisão de literatura / Universal adhesive systems ­ 10 years in Brasil: literature review

Objetivo: analisar, a partir da literatura publicada, os sistemas adesivos universais, conceituando sobre seu desempenho nos diferentes substratos, assim como potenciais estudos executados com eles após 10 anos no Brasil. Materiais e métodos: para esta revisão narrativa, foram pesquisados artigos na língua inglesa nas bases de dados eletrônicas PubMed/Medline, SciELO e Scopus, publicados de 2012 a 2022, período considerado por ser a última década, além dos 10 anos da chegada do sistema adesivo universal ao Brasil. Utilizaram-se os seguintes descritores: universal adhesives (adesivos universais) OR universal adhesive system (sistemas adesivos universais). Realizou-se a inclusão de estudos laboratoriais (in vitro), ensaios clínicos, revisões de literatura e sistemáticas com meta-análise. Resultados: após análise meticulosa, foram selecionados 56 estudos. Os adesivos universais são considerados mais "amigáveis" ao usuário, pois permitem ao clínico a utilização no modo condicione e lave e autocondicionante, principalmente devido à inclusão do monômero MDP ou de monômeros similares. No esmalte, o condicionamento ácido seletivo antes da aplicação do adesivo é recomendado. Permite ser utilizado com uma diversidade de substratos, a aplicação de forma ativa do adesivo melhora a resistência de união. Conclusão: os sistemas adesivos universais foram lançados para tornar os procedimentos de adesão mais simples. Entretanto, mais ensaios clínicos com maiores tempos de acompanhamento são necessários, para avaliar adequadamente a efetividade desse material.(AU)

Objective: To evaluate, from published literature, the universal adhesive systems, conceptualizing their performance, as well as potential studies performed using this material. MATERIAL AND METHODS: This narrative review considered articles in the English language searched on Pubmed/ Medline, Scielo and Scopus from 2012 to 2022, considered period to be the last decade, besides ten years of the universal adhesive system arrived in Brazil. The descriptors "universal adhesive" or "universal adhesive systems" were used. Laboratorial studies (in vitro), clinical trials, literature review and systematic review with meta-analysis were included. RESULTS: 56 studies were included. The universal adhesives are considered more user-friendly, allowing for etch & rinse and self-etch modes, mostly due to MDP monomer or similar monomers inclusion. In enamel selective acid etching before adhesive application is recommended. The system can be used with great amount of substrates and results in superior bond strength when applied through active mode. CONCLUSION: Universal adhesive systems were launched to simplify the adhesion procedure, however more clinical trials with longer follow-ups are required using this material, with adequate evaluation of their effectiveness.(AU)