Development of dental nano composites based on Bis Gma / TEGDMA with antimicrobial activity using MMT nanoparticles loaded with chlorhexidine

• Grant number: 16/01319-9
• Support Opportunities: Regular Research Grants
• Start date: June 01, 2016
• End date: May 31, 2018
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Letícia Cristina Cidreira Boaro
• Grantee: Letícia Cristina Cidreira Boaro
• Host Institution: Universidade de Santo Amaro (UNISA). São Paulo , SP, Brazil

Abstract

Polymeric restorative materials are widely used, but the polymerization shrinkage is still a major drawback as it allows microleakage and secondary caries. A polymeric material with antimicrobial activity could be very useful in many dental procedures such as adhesive cementation, sealants, dental adhesives and direct restorative material. The aim of this study will be to develop nanocomposites with dental purpose using MMT (montmorillonite) loaded with chlorhexidine (CHX) in an organic matrix based BisGMA / TEGDMA. To achieve this goal, the project will be divided into six different stages, each with a specific purpose. Stage 01 - compare the drying oven with the lyophilization of the complex MMT / CHX after the merger of CHX in relation to its lamellar structure by XRD, SEM and TEM. Stage 02 - determine the largest percentage by weight of CHX can be incorporated into the MMT without the occurrence of exfoliation. For this will be incorporated into different concentrations CHX in increments of 1% by weight in MMT until exfoliation occurs, and these mixtures are evaluated by XRD, SEM and TEM. Stage 03 - Six composites will be made the basis of BisGMA / TEGDMA, and the load will be used montmotilonita (MMT) at concentrations of 2.5; 5 to 10% by weight, and half of these composites will chlorhexidine (CHX) incorporated in the MMT and the other not. The release of CHX is evaluated by fluorescence in visible ultra-violet light (255 nm) of three solutions at neutral pH (physiological solution), acid and alkaline by UV spectroscopy (n = 5 for each solution). The antimicrobial activity will be evaluated by inhibition halo formation in agar with three different bacteria (Staphylococcus aureus ATCC 29213, Streptococcus mutans UA 159, and Porphyromonas gingivalis W83). The composites made with the same concentrations of MMT only serve as a control for the antimicrobial activity tests. For each group will be held 5 repetitions. Stage 04 - check the influence of the presence of CHX on the properties of composites. The composites used have the same composition of stage 03. 20 specimens will be made (10x2x1) for each composite. Half will be stored at 37 ° C for 24 hours and the other half stored for 4 months in ethanol solution at 75% at 37 ° C. The elastic modulus of the composite and flexural strength will be obtained by bending test at three points. Sorption will be evaluated on cylindrical specimens (_ = 15 mm h = 1 mm) according to ISO 4049 standards (n = 5). The degree of conversion will be analyzed using FT-IR (n = 5). The pósgel volumetric shrinkage is measured by extensometer (n = 5). Stage 05 - The purpose of this step is to determine the lowest concentration of CHX present in a composite can result in antimicrobial activity. Ten composites will be made based on the BisGMA / TEGDMA, and the load used is montmotilonita (MMT) chlorhexidine (CHX) incorporated in concentrations from 0.05% to 10% by weight. The release of CHX is evaluated by fluorescence in visible ultra-violet light (255 nm) in solution at neutral pH (saline) by UV spectroscopy (n = 5 for each solution). The antimicrobial activity will be evaluated by inhibition halo formation in agar with three different bacteria (Staphylococcus aureus ATCC 29213, Streptococcus mutans UA 159, and Porphyromonas gingivalis W83). For each group will be held 5 repetitions. Stage 06 - in order to verify that the release of CHX remains in stiffer composite (hybrid filler of silica/barium glass). At this stage the composite will have different compositions, and the release of chlorhexidine will be evaluated by fluorescence in ultraviolet. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

FLÁVIA GONÇALVES; LUIZA MELLO DE PAIVA CAMPOS; EZEQUIAS COSTA RODRIGUES-JÚNIOR; FABRÍCIA VIANA COSTA; PAMELA ADELINE MARQUES; CARLOS EDUARDO FRANCCI; ROBERTO RUGGIERO BRAGA; LETÍCIA CRISTINA CIDREIRA BOARO. A comparative study of bulk-fill composites: degree of conversion, post-gel shrinkage and cytotoxicity. Brazilian Oral Research, v. 32, 2018-03-08. (13/07229-3, 16/01319-9)

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. A comparative study of bulk-fill composites: degree of conversion, post-gel shrinkage and cytotoxicity. BRAZILIAN ORAL RESEARCH, v. 32, p. 9-pg., 2018-01-01. (16/01319-9, 13/07229-3)

CIDREIRA BOARO, LETICIA CRISTINA; CAMPOS, LUIZA MELLO; COSTA VARCA, GUSTAVO HENRIQUE; RIBEIRO DOS SANTOS, TAMIRIS MARTINS; MARQUES, PAMELA ADELINE; SUGII, MARI MIURA; SALDANHA, NATHALIA RAMALDES; COGO-MULLER, KARINA; BRANDT, WILLIAM CUNHA; BRAGA, ROBERTO RUGGIERO; et al. Antibacterial resin-based composite containing chlorhexidine for dental. Dental Materials, v. 35, n. 6, p. 909-918, JUN 2019. (14/23144-0, 16/01319-9)