Bioactive Polymeric Dental Materials Based on Amorphous Calcium Phosphate

Abstract

The effectiveness of acrylic-based visible light curable composites with amorphous calcium phosphate (ACP) as the filler phase to release Ca 2+ and phosphate (PO 4 ) ions in aqueous media was enhanced with the incorporation of zirconyl dimethacrylate (ZrM) or 3-methacryloxypropyltrimethoxysilane (MPTMS) as coupling agents. Relatively hydrophobic resin-based composites formulated with these coupling agents were found to more rapidly release these ions over a longer period to establish solution Ca 2+ and PO 4 concentrations much higher than those obtained from similar composites without these coupling agents. The increased effectiveness of the former composites was comparable to that observed with more hydrophilic composites formulated with 2-hydroxyethyl methacrylate. In addition, composite strength was not compromised by the incorporation of MPTMS or ZrM. These results suggest that coupling agents make ACP-filled composites even more effective as bioactive dental materials for use in clinical applications where preventing demineralization or promoting remineralization of tooth structures is desirable.Because of their excellent biocompatibility with both soft and hard tissue, crystalline calcium orthophosphates, especially hydroxyapatite (HAP) and those capable of converting to HAP are finding increasing use as prophylactic, prosthetic, adhesive and restorative materials in dental and other biomedical applications (7-J). Polymeric calcium phosphate composites and cements have also been developed (6-11) in an effort to enhance the toughness, strength and handling properties of these materials.By contrast, amorphous calcium phosphate (ACP), which has an approximate compositional formula of Ca 3 (P0 4 )2 3H 2 0 (12) and is an important intermediate in This chapter not subject to U.S.

Quantitative Assessment of the Efficacy of Amorphous Calcium Phosphate/Methacrylate Composites in Remineralizing Caries-like Lesions Artificially Produced in Bovine Enamel

“…The permeability of the resin matrix to water, necessary to facilitate the release of ACP filler Ca2+ and P04 ions and their transport to the composite surface (Skrtic et al, 1995;Antonucci et al, 1996), most probably also promoted the flux of ions between the tooth surface and the external solution milieu. In particular, H+ ion influx and subsequent increase in intralesion fluid acidity during the DS-exposure stage of dynamic treatment B could have contributed to the lower net remineralization compared with static treatment A by further dissolving tooth mineral, especially some of the new HA deposited during the RS stage.…”

Silica‐ and zirconia‐hybridized amorphous calcium phosphate: Effect on transformation to hydroxyapatite

“…[2][3][4][5] We have recently developed a unique bioactive composite based on a polymer matrix phase derived from ambient polymerization of acrylic monomers and a filler phase consisting of ACP. 6,7 Pure ACP proved to be an unsuitable filler for this type of composite because of its rapid internal conversion to HAP. However, when the ACP was stabilized by ions that retard its conversion (P 2 O 7 4− primarily, and to the lesser extent Mg 2+ ), it was possible to take advantage of ACP's relatively high solubility and obtain substantial release of Ca and PO 4 .…”

“…Moreover, the levels attained in solution from these releases were sustainable, and could promote the recovery of mineraldeficient tooth structures in in vitro situations 8 even though only a small portion of the theoretically available mineral ions is actually released into external solutions. 7 However, such bioactive composites are relatively weak mechanically because ACP does not act as reinforcing filler in a manner similar to that of silanized glass fillers commonly used in conventional dental composites. To strengthen ACP composites by making ACP more amenable to coupling agents, we have incorporated during ACP synthesis tetraethoxysilane (TEOS) and zirconyl chloride (ZrOCl 2 ) as hybridizing agents with encouraging results.…”

Physicochemical evaluation of bioactive polymeric composites based on hybrid amorphous calcium phosphates

“…3,4 When the ACP was stabilized by ions that retard its conversion to HAP (primarily pyrophosphate P 2 O 7 4Ϫ , and to the lesser extent Mg 2ϩ ), it was possible to take advantage of ACP's solubility and obtain substantial release of Ca 2ϩ and PO 4 ions. Moreover, the solution levels of Ca 2ϩ and PO 4 attained from these releases were sustainable for sufficient periods of time to promote the recovery of mineral-deficient tooth structures in in vitro situations.…”