A comparative study of bulk-fill composites: degree of conversion, post-gel shrinkage and cytotoxicity

Author(s)

Goncalves, Flavia ; de Paiva Campos, Luiza Mello ; Rodrigues-Junior, Ezequias Costa ; Costa, Fabricia Viana ; Marques, Pamela Adeline ; Francci, Carlos Eduardo ; Braga, Roberto Ruggiero ; Cidreira Boaro, Leticia Cristina

• Document type: Journal article
• Source: BRAZILIAN ORAL RESEARCH; v. 32, p. 9-pg., 2018-01-01.

Abstract

Bulk-fill composites are claimed to be restorative materials used in deep preparations and effectively photoactivated in layers up to 4 mm. The aim of the present study was to evaluate the degree of conversion, post-gel volumetric shrinkage, and cytotoxicity of six bulk-fill and two conventional composites. Degree of conversion was determined by FTIR spectroscopy; post-gel volumetric shrinkage was determined using the strain gauge method; and cytotoxicity in human fibroblasts was evaluated indirectly by the MTT assay. Data were subjected to one-way ANOVA/Tukey's test (alpha = 0.05). All materials, including bulk-fill and conventional composites, were classified as non-toxic, with cell viability higher than 70%. Bulk-fill composites exhibited volumetric shrinkage similar to or lower (1.4 to 0.4%) than that of conventional composites (1.7-2.1%). However, only four of the bulk-fill composites were able to sustain a homogeneous conversion at the 4-mm depth. Despite their non-toxicity and shrinkage similar to that of conventional materials, not all commercial bulk-fill materials were able to maintain a conversion as high as 80% of the superficial layer, at the 4-mm depth, indicating some failure in the bulk-fill design of some commercial brands. Therefore, the use of bulk-fill materials in dental practice is advantageous, but special attention should be given to the selection and correct use of the materials. (AU)

• FAPESP's process: 16/01319-9 - Development of dental nano composites based on Bis Gma / TEGDMA with antimicrobial activity using MMT nanoparticles loaded with chlorhexidine
• Grantee: Letícia Cristina Cidreira Boaro
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/07229-3 - ASSESSMENT OF CLAY MINERAL NANOPARTICLE ADDITION IN BISGMA/TEGMA PHOTO-ACTIVATED POLYMERIC MATRICES FOR DENTISTRY APPLICATION
• Grantee: Luiza Mello de Paiva Campos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral