Effect of thickness on shrinkage stress and bottom-to-top hardness ratio of conventional and bulk-fill composites.

This study evaluated the effect of the material thickness on shrinkage stress and bottom-to-top hardness ratio of conventional and bulk-fill composites. Six commercial composites were selected based on their different technologies: Two conventional (C1, C2), two high-viscosity bulk-fill (HVB1, HVB2), and two low-viscosity bulk-fill (LVB1, LVB2). Shrinkage stress was analyzed for five specimens with 2 mm thickness (C-factor 0.75 and volume 24 mm3 ) and five specimens with 4 mm thickness (C-factor 0.375 and volume 48 mm3 ) for 300 s in a universal testing machine. Bottom-to-top hardness ratio values were obtained from Knoop microhardness measurements in specimens with 2- and 4-mm thickness (n = 5). Thickness increase resulted in significantly higher shrinkage stress for all materials with the exception of HVB2 and LVB1. C1, C2, HVB2, and LVB1 showed lower bottom-to-top hardness ratios at 4 mm than at 2 mm. Only LVB2 presented a bottom-to-top hardness ratio lower than 80% at 2 mm, while HVB1 surpassed this threshold at 4 mm of depth. The results suggest that the increase of composite thickness affected the shrinkage stress values. Also, thickness increase resulted in lower bottom-to-top hardness ratio. HVB1 showed better behavior than other bulk-fill materials, with low stress and adequate bottom-to-top hardness ratio at 4 mm thickness.

Tratamento estético por meio de restaurações diretas em resina composta para hipocalcificação de esmalte: 18 meses de controle clínico / Aesthetic treatment through direct composite resin restorations for enamel hypocalcification: 18 months of clinical control

Atualmente, tem se tornado rotina a busca por procedimentos que realcem o sorriso. Neste contexto, técnicas de clareamento dental, microabrasão, restaurações diretas em resina composta, bem como indiretas em cerâmica, são abordagens viáveis para restabelecer alterações do esmalte na região anterior. O objetivo deste caso clínico é relatar uma alternativa de tratamento às lesões de mancha branca extensa em dentes anteriores, compatíveis com hipocalcificação de esmalte, em uma paciente jovem, por meio de restaurações diretas em resina composta. Devido à profundidade e extensão das lesões, restaurações utilizando a técnica de inserção incremental foram realizadas, uma vez que proporcionam menor contração volumétrica do material. Além disso, a estratificação com compósitos para dentina, esmalte e translúcido garantiu a obtenção de um resultado estético harmônico. Após o controle clínico de 18 meses, foi possível verificar que as restaurações apresentavam-se satisfatórias, ausência do comprometimento da interface adesiva, necessitando apenas de repolimento para manutenção do brilho superficial. Desta maneira, na atual Odontologia de mínima intervenção, a abordagem com resina composta foi uma alternativa restauradora estética, conservadora e eficaz para o tratamento de lesões de hipocalcificação de esmalte na região anterior (AU).

Nowadays, the search for procedures that highlight the smile has become routine. In this context, dental bleaching, microabrasion, direct composite resin restorations techniques, as well as indirect ceramics resin are viable approaches to reestablish enamel alterations in the anterior region. The objective of this clinical case is to report an alternative treatment for lesions of extensive white spot in anterior teeth, compatible with enamel hypocalcification in a young patient with direct composite resin restorations. Due to lesions depth and extent, restorations using the incremental insertion technique were performed, as they provide less volumetric contraction of the material. In addition, the stratification with composites for dentin, enamel and translucent established a harmonious aesthetic result. After clinical control of 18 months, it was possible to verify that the restorations were satisfactory, there was absence of adhesive interface deterioration, only requiring repolishing to maintain the superficial brightness. So in the current minimal intervention Dentistry the composite resin approach was an aesthetic, conservative and effective restorative alternative for treatment of enamel hypocalcification lesions in anterior region (AU).