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Title: 0581 - Bioactive Composites Containing Calcium Phosphate Particles: Mechanical Properties and Ion Release

Authors:

Livia Natale, University of São Paulo
Marcela Rodrigues, Universidade Cruzeiro do Sul
Yvete Alania, University of São Paulo
Marina Chiari, University of São Paulo
Marycel Cotrim, Instituto de Pesquisas Energéticas e Nucleares
Oscar Vega, Instituto de Pesquisas Energéticas e Nucleares
Roberto Braga (Presenter)
University of São Paulo

Abstract:

Objectives: The objective of this study was to compare the mechanical properties and ion release of composites containing different calcium phosphate (CaP) particles, namely, non-functionalized (NF), functionalized with triethylene glycol dimethacrylate (TF) or diethylene glycol dimethacrylate (DF). The null hypothesis was that particle functionalization would not affect composite behavior.

Methods: Dicalcium phosphate dihydrate particles (DCPD) were obtained by sol-gel synthesis. For the functionalized particles, DEGDMA or TEGDMA was added to one of the precursor solutions. Composites were formulated with 15vol% DCPD, 45vol% barium glass and 40vol% BisGMA/TEGDMA matrix. Camphorquinone and tertiary amine (EDMAB) were added as photoinitiators. A composite containing 60vol% of barium glass was tested as control. Biaxial flexural test specimens (12x1 mm, n=10) stored for 24h or 60 days in water were tested in a “piston on three spheres” jig. Ca and P release from specimens stored in saline solution (pH 7) up to 60 days were determined by spectrometry (ICP-OES, n=5). Data were analyzed by two-way ANOVA/Tukey test (alpha: 5%).

Results: Mechanical properties are shown in the Table. DCPD type affected initial flexural strength only (DF>TF, p<0.05). After 60d-storage, only NF was similar to the control. Flexural modulus was not affected by the presence of DCPD or storage time (p>0.05). Ca concentrations (ppm) decreased from 1.8-3.9 (15d) to 1.3–1.7 (60d), while P concentrations decreased from 0.4-1.0 (15d) to 0.1-0.2 (60d), with no statistically significant differences among composites at any given time (p>0.05). NF showed a 66% reduction in Ca release between 15d and 60d, while DF and TF showed 32% and 28% reductions, respectively. For P, the reductions observed between 15d and 60d were 80% (NF), 75% (DF) and 66% (TF).

Conclusions: Within the limitations of this study, it is possible to conclude that only composite initial strength was affected by DCPD functionalization.

Table(s):

Composites Biaxial flexural strength (MPa) Flexural modulus (GPa)
24 hours 60 days 24 hours 60 days
Control (60vol% barium glass) 114.9 (17.9) ABa 125.9 (30.8) Aa 11.0 (2.2) Aa 15.6 (1.5) Aa
NF (15 vol% non-functionalized DCPD + 45 vol% barium glass) 106.7 (14.5) ABa 96.0 (13.0) ABa 13.3 (2.1) Aa 14.8 (5.0) Aa
DF (15 vol% DEGDMA-functionalized DCPD + 45 vol% barium glass) 118.2 (27.4) Aa 92.5 (31.9) Ba 13.6 (3.8) Aa 11.8 (3.6) Aa
TF (15 vol% TEGDMA-functionalized DCPD + 45 vol% barium glass) 87.4 (16.5) Ba 94.1 (16.8) Ba 13.9 (4.4) Aa 11.2 (4.8) Aa

This abstract is based on research that was funded entirely or partially by an outside source:
FAPESP 2015/15019-4

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: None

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