Effectiveness of ultrasonic activation over glycolic acid on microhardness, cohesive strength, flexural strength, and fracture resistance of the root dentin.

OBJECTIVES: The aim of this study was to evaluate the effectiveness of ultrasonic activation (US) over glycolic acid on microhardness, cohesive strength, flexural strength, and fracture resistance of root dentin, comparing with conventional final irrigation protocols. METHODS: Samples were obtained from 140 extracted bovine teeth and distributed into four test groups: microhardness (50 teeth), cohesive strength (15 teeth), flexural strength (15 teeth), and fracture resistance (60 teeth). In all four tests, specimens were subdivided into five groups, according to final irrigation protocols: G1: distilled water (DW); G2: 17% ethylenediaminetetraacetic acid (EDTA); G3: 17% glycolic acid (GA); G4: 17% EDTA + US; and G5: 17% GA + US. The duration time of each protocol was set in 1 min. After irrigation protocols, the Vickers tester was used to evaluate microhardness and the universal testing machine was used to evaluate the cohesive strength, flexural strength, and fracture resistance of the root dentin. One-way ANOVA test and the Tukey HSD were used for multiple comparison tests in all evaluations (α = 5%). RESULTS: In general, groups 2 (EDTA), 4 (EDTA + US), and 5 (GA + US) promoted the highest reduction of microhardness, being statistically different from other groups (p < 0.05). Cohesive strength, flexural strength, and fracture resistance data revealed that no differences between groups were observed (p > 0.05). CONCLUSIONS: The association of GA and US results in microhardness reduction, with no influence on cohesive strength, flexural strength, and fracture resistance of the root dentin. CLINICAL RELEVANCE: The use of US over GA has no influence on some mechanical properties of root dentin.

Eficácia de agentes químicos na desinfecção de tubetes anestésicos odontológicos / Effectiveness of chemical agents in disinfecting dental anesthetic cartridges

Durante o atendimento odontológico, o paciente pode ser exposto a várias fontes de contaminações, por isso a equipe odontológica deve sempre implementar ações de biossegurança. Materiais não autoclaváveis, como os tubetes anestésicos, necessitam ser desinfetados previamente ao seu uso, pois não são estéreis, podendo transmitir patógenos entre os pacientes. Este estudo objetivou avaliar e comparar a eficácia de três soluções desinfetantes na redução da carga microbiana em tubetes de anestésicos odontológicos. Os tubetes anestésicos (n = 31) foram escolhidos aleato-riamente e submetidos a diferentes métodos e agentes desinfetantes (Álcool 70%, Dióxido de Cloro 7%; Cloreto de benzalcônio 5,2% com Polihexametileno biguanida 3,5%). Após a desinfecção por métodos de imersão ou fricção, os tubetes foram semeados em meio de cultura contendo caldo tripticase de soja e incubados (48h/37 ºC). Amostras do meio de cultura líquido foram repicadas e semeadas em ágar tripticase de soja, incubado durante 48h a 37 ºC. O crescimento microbiano foi observado pela presença de unidades formadoras de colônias (UFCs) crescidas no ágar. O estudo concluiu que os produtos Álcool 70% e Cloreto de benzalcônio 5,2% com Polihexametileno biguanida 3,5% demostraram ser mais eficazes na eliminação da carga microbiana dos tubetes pelo método de fricção, e que realmente os tubetes anestésicos tem sua superfície externa contaminada. O estudo comprovou ser o método de fricção do agente desinfetante mais eficaz na redução da carga microbiana comparado a imersão. Dos agentes testados, o Dióxido de Cloro 7% não demonstrou um nível de desinfecção satisfatório.

During dental care, the patient may be exposed to various sources of contamination, so the dental team should always implement biosecurity actions. Non-autoclavable materials such as anesthetic cartridges need to be di-sinfected prior to use because they are not sterile and can transmit pathogens between patients. This study aimed to evaluate and compare the effectiveness of three disinfectant solutions to reduce microbial load in dental anesthetic cartridges. Anesthetic cartridges (n = 31) were randomly chosen and submitted to different methods and disinfectants (70% Alcohol, 7% Chlorine Dioxide; 5.2% Benzalkonium Chloride with 3.5% Polyhexamethylene Biguanide). After immersion or friction methods of disinfection, the tubes were seeded in culture medium containing trypticase soy broth and incubated (48h/37 ºC). Samples of liquid culture medium were picked and seeded in trypticase soy agar, incubated for 48h at 37 ºC. Microbial growth was observed by the number of colonies forming units (CFUs) grown on the agar. The study concluded that 70% Alcohol and 5.2% Benzalko-nium Chloride with 3.5% Polyhexamethylene biguanide have been shown to be most effective in eliminating the microbial contamination of the cartridges by the friction method, and that the anesthetic cartridges actually have contamination of their external surface. The study proved that the friction method is most effective in reducing microbial load compared to immersion. Of the agents tested, 7% Chlorine Dioxide did not show a satisfactory level of disinfection.