773 Endodontic Intelligent Release System for Apexification using Calcium Hydroxide Microspheres

Friday, March 23, 2012: 2 p.m. - 3:15 p.m.
Presentation Type: Poster Session
N.M. KARIM1, A. STROM1, B. OSBORN1, A. ARORA1, T. KOMABAYASHI2, and X. LIU1, 1Biomedical Sciences, Baylor College of Dentistry, Dallas, TX, 2Endodontics, Baylor College of Dentistry, Dallas, TX
Objectives:  Apexification therapy requires repeated applications of a calcium hydroxide (CH) slurry owing to burst release of CH and loss of material in the periapical tissue. There is a need for a sustained slow release delivery system for CH. The purpose of this study was to engineer an innovative release system to deliver a steady stream of both Ca2+ and OH- ions to the open apex of permanent teeth for a period of up to one year. In addition to creating a slow release vehicle for CH, the buffering effect of the teeth was also investigated.

Methods:  An oily matrix was used as a CH vehicle and to form microspheres, as well as an alginate outer coating, aiding in the slow release of ions. The CHMS were compared to a commercially available CH medicament and to CH powder as controls. The release experiments were performed in extracted teeth(n=6) and in plastic centrifuge tubes(n=3) to determine the buffering effect occurring within teeth. The calcium release was measured with ultraviolet-visible spectroscopy and the pH was monitored with a pH meter.

Results:  Results showed that the CHMS formulations showed the maximum sustained release in comparison to both controls. We were able to release Ca2+ for >4 months from the alginate-CHMSs in contrast to controls, which were depleted after one week under sink conditions. We also demonstrated control over the release profile of CH ions by varying the thickness of the alginate layer. The pH of samples from extracted teeth never rose above 9, whereas samples from centrifuge tubes had consistently high pH(12-14) indicating the buffering effect of teeth.

Conclusions: CHMSs present a viable alternative for currently available products for apexification. The slow release of Ca2+ and OH- should eliminate the need for periodic removal and refreshing of traditional intra-canal medicaments.

Support: NIH P30DE20742 & KL2RR024983

This abstract is based on research that was funded entirely or partially by an outside source: NIH P30DE20742 & KL2RR024983

Keywords: Bioengineering, Delivery systems, Endodontics, Root canal fillings and Sealants