The ability of orthodontists and laypeople to discriminate mandibular stepwise advancements in a Class II retrognathic mandible.

OBJECTIVES: This study analysed the ability of orthodontists and laypeople to discriminate mandibular stepwise advancements. MATERIALS AND METHODS: Four pictures (in duplicate) were taken of a male patient with Class II malocclusion and mandibular deficiency with the mandible positioned in habitual maximum intercuspation (HMI) and with stepwise advancements of 2mm, 4mm and 6mm. These images were examined by orthodontists (n=30) and laypeople (n=30). The Wilcoxon signed-rank test was used to evaluate intra-examiner agreement. Intra-examiner ability to discriminate stepwise mandibular advancements was examined by Friedman's test. A Mann-Whitney's test was carried out to analyse score difference between orthodontists and laypeople. Type I error (alpha) was set as 5% for all statistical tests. RESULTS: We observed a satisfactory to excellent level of methodological reliability. While laypeople were able to notice mandibular advancements ≥4 mm (p<0.05), orthodontists were able to observe mandibular advancements ≥2 mm (p<0.05). The orthodontists were more critical than laypeople with regard to the facial profile evaluation when facial convexity increased (p<0.001), but no significant difference was observed when the sagittal maxillo-mandibular relationship approached normality (p<0.05). CONCLUSIONS: Considering that the mean sagittal mandibular growth due to the use of functional orthopaedic appliances is reported in the literature as 2mm, it seems that laypeople may not able to discriminate this amount of change in facial-profile attractiveness.

Influência do clareamento dental fotoativado na resistência da união adesiva ao esmalte / Influence of photoactivated bleaching on enamel bond strength

Objetivo: Avaliar a influência do clareamento dental com peróxido de hidrogênio a 35% (PH35), associado ao emprego de fonte luminosa de ativação, na resistência da união adesiva ao esmalte. Materiais e Métodos: Sessenta dentes bovinos incisivos hígidos foram divididos em seis grupos (n=10) de acordo com a realização do tratamento clareador, fotoativação do gel clareador, e tempo decorrido pós-clareamento para realização das uniões adesivas (24h ou 14d), sendo: G1 ? Sem clareamento (controle) / Sem fotoativação / 24h; G2 ? Sem clareamento (controle) / Sem fotoativação / 14d; G3 ? Clareamento / Sem fotoativação / 24h; G4 ? Clareamento / Sem fotoativação / 14d; G5 ? Clareamento / Fotoativação / 24h; G6 ? Clareamento / Fotoativação / 14d. Os dentes foram seccionados, suas coroas incluídas em matrizes PVC, e suas superfícies vestibulares planificadas. Os grupos controle foram armazenados em saliva artificial (37ºC) por um período de 24h ou 14d. Os grupos clareados foram expostos ao gel de PH35 (Whiteness HP Maxx - FGM) por um tempo total de 45 minutos (03 aplicações de 15 minutos cada). Quando fotoativado, o gel foi exposto ao aparelho fotopolimerizador de led (900 mW/cm2) (02 exposições de 20s cada). Em seguida, 24h ou 14d pós-clareamento, cilindros de resina composta foram confeccionados sobre as superfícies de esmalte. Os corpos-de-prova foram armazenados em água destilada (24h) (37ºC) até o ensaio de cisalhamento. Resultados: A maior média de resistência foi obtida para G3 (2,12 MPa), sendo a menor para G1 (1,29 MPa). A ANOVA 2-way (? ? 0,05) não demonstrou diferenças significativas para ambos os fatores considerados (clareamento e tempo de armazenamento), bem como para a interação entre estes. Conclusão: O clareamento com PH35, bem como o uso de fonte fotoativadora associado ao gel clareador, não interferiram na resistência da união adesiva ao esmalte, independente do tempo pós-clareamento adotado para realizar as uniões.

Objective: Evaluate the influence of dental bleaching with 35% hydrogen peroxide (35HP), associated to a photocuring source, on the enamel shear bond strength. Materials and method: Sixty sound incisive bovine teeth were randomly divided into six groups (n=10) according to bleaching treatment (not bleached, bleached, or photoactivated bleached) and storage time (24h or 14d), being: G1 ? Not bleached (control) / Not photoactivated / 24h; G2 ? Not bleached (control) / Not photoactivated / 14d; G3 ? Bleached / Not photoactivated / 24h; G4 ? Bleached / Not photoactivated / 14d; G5 ? Bleached / Photoactivated / 24h; G6 ? Bleached / Photoactivated / 14d. Teeth were sectioned, had crowns included in a PVC matrix, and the enamel surfaces gridded and polished with silicon carbide abrasive papers. Control groups were stored in artificial saliva (37ºC) for 24h or 14d. Bleached groups were exposed to 35HP gel (Whiteness HP Maxx ? FGM) for a period of 45 minutes (03 applications of 15 minutes each). Photoactivated groups had bleaching gel exposed to a led source (900 mW/cm2) twice for 20s each. 24h or 14d post-bleaching, composite resin cylinders were performed at enamel surfaces. After storage in distilled water (37ºC) (24h), samples were submitted to the shear bond test. Results: The higher mean value (2,12 MPa) was associated to G3, while the lower one (1,29 MPa) was associated to G1. ANOVA ? 2way (a £ 0,05) showed no significant differences for both factors (bleaching and storage time), so the interaction between these factors. Conclusion: Bleaching with 35HP, farther using a photocuring source to activate the gel, had no influence on the enamel shear bond strength, independently of post-bleaching time adopted to perform adhesive bonds.