Degradation of polymeric restorative materials subjected to a high caries challenge

Very interesting study on composites. You need to look at this one as it illustrates why high caries individuals restorative may break down faster. 

Dental Materials
Volume 27, Issue 3, March 2011, Pages 244-252

---

Márcio A.P. Borges^a, Irma C. Matos^a, , , Luis C. Mendes^b, Ailton S. Gomes^b and Mauro S. Miranda^c

^a Brazilian Navy, Navy Central Clinic, Rio de Janeiro, RJ, Brazil

^b Institute of Macromolecules, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil

^c Department of Dentistry, School of Dentistry, State University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil

Received 14 December 2009;  

revised 10 April 2010;  

accepted 15 October 2010.  

Available online 13 November 2010. 

Abstract

Objectives

The aim of this study was to evaluate the degradation of different resin filling materials after a caries challenge, by high performance liquid chromatography (HPLC) and contact angle (θ) measurement.

Methods

Four different polymeric restorative materials (a resin composite, a polyacid-modified resin composite, an ormocer and a resin-modified glass ionomer cement) were tested. Five samples (30 mm × 6 mm × 2 mm) of each material were formed in a Teflon mold, following the manufacturer's instructions. After pH cycles, the solutions were injected in an HPLC. The θ was obtained, before and after pH cycle, by a goniometer at 60% air humidity and 25 °C. A distilled water drop (0.006 ml) was put on the material surface, and after 6 min, 10 measures were obtained at 20 s intervals. Each sample received 4 drops, one at a time, on different areas.

Results

HPLC results showed elution of byproducts in all materials. This was greater in the acid medium. Bis-GMA and TEGDMA were detected in TPH Spectrum and Definite residues. Analyses of the contact angle by ANOVA and Student–Neuman–Keuls's test showed that the surfaces of TPH Spectrum, Dyract AP and Definite were altered, except Vitremer (p < 0.05).

Significance

All materials tested degraded on a caries simulated medium, suggesting that a great effort should be made to disseminate oral health information, since a high caries challenge environment (low pH) can lead to dental composite degradation, with potential toxic risks to patients.