RD94 In Indirect Pulp-Capping Situation Induces Reactionary Dentin Formation

RD94 a new experimental Ca3SiO5-based restorative cement intends to be a glass ionomer cement and composite-resin substitute in restorative dentistry. Objectives:to evaluate in vivo the biocompatibility and bioactivity effects of RD94 as assumed from the formation of reactionary dentin. Methods:Using the rat as an animal model, half-moon cavities were prepared on the mesial aspect of the first maxillary molar without pulp exposure. The cavities were then left unfilled (sham group) or filled either with a glass-ionomer cement (control group) or with RD94 (experimental group). The rats were killed by perfusion through the heart with the fixative solution 8, 15, 30 days, and 3 months after the dental treatment. Block sections including the three maxillary molars were demineralised and processed for light microscopy. Measurements were done on micrographs obtained after histological observations. Results: After 8 days, a slight inflammatory reaction was seen in each group. In the RD94 group, a dentin layer of reactionary dentin starts to be formed, by contrast with the 2 other groups. After 15 days, a tendency of spontaneous repair was observed in the pulps of the sham and control groups. In the RD94 group, the pulp near the cavity retracts, covered by a 40-80 µm thick layer of reactionary dentin. In the RD94 group, after one month, the mesial part of pulp was partially filled with a homogenous dentin-like material (160µm) whereas the rest of pulp appeared normal. After three months, RD94 induced the formation of a homogenous reactionary dentin but the thickness of this layer was unchanged between 1 and 3 months. Conclusions:The present data 1-suggest that RD94 displays novel bioactive properties. 2- This new cement stimulates the formation of reactionary dentin in the rat molar model shortly after a switch on, 3- but there is actually a “switch off”, keeping the remaining pulp alive.