Apatite-forming ability of TheralCal pulp capping.

Objective: A liner must perform as a barrier and protect the dental pulpal complex. Calcium-silicate MTA materials recently used for pulp capping demonstrate the ability to form hydroxyapatite when immersed in simulated body fluid (Gandolfi et al. 2009, 2010). TheraCal is a light-curable resin formula which contains CaO mineral oxides, designed to be used as liner and pulp capping material that demonstrates good biocompatibility/absence of cytotoxicity. The aim of this study is to evaluate the ability of this material to form hydroxyapatite when immersed in a phosphate-containing solution. Method: TheraCal (Bisco Inc, USA), Control paste (without mineral oxides) (Bisco Inc, USA), ProRoot MTA (Dentsply, USA) were used. Sample discs (n=10 for each material) were prepared. The materials were placed in a PVC mold (8mm dia x 1.6mm) and light-cured on both surfaces for 20 seconds (per manufacture) using a LED light, after the application of a transparent polyester strip. The discs were de-molded, immersed in 10mL of a phosphate-containing solution (Dulbecco's Phosphate Buffered Saline, DPBS) in a sealed container and stored at 37°C. The surface chemistry, morphology and formation of apatite on samples surface after 1, 7, 14 and 28 days of immersion in DPBS was assessed by ESEM-EDX, micro-Raman and FT-IR techniques. Results: TheraCal demonstrated the capacity to form apatite on its surface after 24 hours immersion in DPBS, as did ProRoot MTA. Amorphous apatite (952 cm-1 Raman band) was detected within the first 24 hours, while a more crystalline apatite (960 cm-1 Raman band) was noticed at 7days. No deposit was detected on the Control. Conclusions: TheraCal is a calcium-releasing material able to induce the formation of apatite and represents a promising material in direct pulp-capping clinical/surgical procedures. The ability to form apatite may play a critical/positive role in new dentin formation.