Heat Development in the Pulp Chamber During Curing Process of Resin-Based Composite Using Multi-Wave LED Light Curing Unit

Objective: The study aimed to investigate factors contributing to heat development during light curing of a flowable bulk-fill resin-based composite (SDRTM, Lot # 602000876, Dentsply Sirona, Konstanz, Germany) (RBC). Materials and Methods: Temperatures were measured with calibrated thermocouples. A multi-wave light-emitting diode (LED) light curing unit (LCU) was used (Ivoclar Vivadent, Schaan, Lichtenstein). In all experiments, the RBC was first cured (cured) for 30 s and, after 5 min of recovery time, received a second LCU irradiation (post-cured) for 30 s. The exothermic reaction was measured by calculating the Δ temperature between cured and post-cured RBC. In a cylinder-shaped polymer mold, temperature was recorded inside of RBC during curing (part 1) and light transmission through RBC during curing was investigated (part 2). Pulpal temperatures were assessed in an extracted third molar during light curing (part 3). Data were statistically analyzed using one-way ANOVA (α=0.05). Results: Increased thickness of RBC led to decreased pulp chamber temperatures. Inside RBC, there was a large variation in heat development between the cured and post-cured groups (p Conclusion: The irradiance of the LCU seemed to be a more important factor than exothermic reaction of RBCs for pulp chamber heat development. Flowable bulk-fill RBCs can act as a pulpal insulator against LCU irradiation, despite their exothermic curing reaction

Hydroxyl radicals generated by hydrogen peroxide photolysis recondition biofilm-contaminated titanium surfaces for subsequent osteoblastic cell proliferation

Titanium dental implants have been successfully used for decades; however, some implants are affected by peri-implantitis due to bacterial infection, resulting in loss of supporting bone. This study aimed to evaluate the effect of an antimicrobial chemotherapy employing H2O2 photolysis—developed to treat peri-implantitis—on biofilm-contaminated titanium surfaces in association with osteoblastic cell proliferation on the treated surface. Titanium discs were sandblasted and acid-etched, followed by contamination with a three-species biofilm composed of Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mitis. This biofilm model was used as a simplified model of clinical peri-implantitis biofilm. The discs were subjected to ultrasound scaling, followed by H2O2 photolysis, wherein 365-nm LED irradiation of the disc immersed in 3% H2O2 was performed for 5 min. We analysed proliferation of mouse osteoblastic cells (MC3T3-E1) cultured on the treated discs. Compared with intact discs, biofilm contamination lowered cell proliferation on the specimen surface, whereas H2O2 photolysis recovered cell proliferation. Thus, H2O2 photolysis can recover the degraded biocompatibility of biofilm-contaminated titanium surfaces and can potentially be utilised for peri-implantitis treatment. However, to verify the findings of this study in relation to clinical settings, assessment using a more clinically relevant multi-species biofilm model is necessary