Methods: In vivo: Deep class V cavities were prepared on the buccal surface of 24 human premolars (n=6). Impressions were taken and inlays were prepared and cemented with SmartCem 2 resin-based cement (Caulk Dentsply). In G1v and G2v, the teeth were extracted at 7 and 30 days after the clinical procedures, respectively. In G3v and G4v (controls), the cavity floor was lined with Life (Kerr Corp.) before cementation and the teeth extracted at 7- and 30-day periods. Extracted teeth were processed for histological assessment. In vitro: Thirty-six dentin discs placed in artificial pulp chambers had their occlusal surfaces treated as follows: G1t- control (no treatment); G2t- Dycal Life; and G3t- SmartCem 2. After 24 hours, the extracts (culture medium + components of cements that diffused across dentin) were collected and applied for 24h on MDPC-23 cells. Data from cell metabolism (MTT assay) and alkaline phosphatase activity (ALP) were statistically analyzed.
Results: In vivo: At 7 days, 4 samples of G1v exhibited moderate pulp inflammation and slight tissue disorganization. In G3v, 2 samples presented slight inflammation and odontoblast layer disruption. At 30 days, 4 samples of G2v exhibited slight inflammation. Only 1 sample showed moderate inflammatory response and tissue disorganization. In vitro: MTT assay showed that G1t and G3t differed significantly from G2t (p<0.05). However no statistical difference was observed between G1t and G3t (p>0.05) in which the cells presented normal metabolism. Concerning ALP activity no statistical difference occurred among all groups.
Conclusions: Despite the very low transdentinal cytotoxicity of the resin-based luting cement SmartCem 2, this dental material may cause persistent chronic inflammatory reaction and superficial pulp tissue disorganization when applied in deep cavities prepared in human teeth.