SUMMARY Objective: This study evaluated the effect of preheating resin composites (RCs) on the clinical performance of class I restorations during a 36-month period using a split-mouth, double-blinded randomized design. Methods and Materials: A total of 35 patients were selected. Every patient received one pair of class I nanofilled resin composite (RC, Filtek Z350 XT) posterior restorations (n=70). One side of the mouth received preheated composites; on the other side, the composite was placed in a nonheated state following the manufacturer’s instructions. These restorations were evaluated at 1-week (baseline), 12-months, 24-months, and 36-months using the FDI World Dental Federation criteria. The statistical analyses were also performed using the Wilcoxon and Friedman tests with the level of significance set at 0.05. Results: After 36 months, 33 patients attended the recall visits, and 66 restorations were evaluated. The Friedman and Wilcoxon signed-rank tests revealed insignificant differences between both groups (p>0.05) for all FDI parameters. However, a significant difference was detected for staining as a criterion at 36 months (p=0.01). Moreover, a significant difference in the staining was detected when the baseline and 36 months were compared in the nonheated RC group (p=0.001). For esthetic, functional, and biological properties, the nonheated composite exhibited 93.9%, 100%, and 100% of the clinically accepted scores, respectively, and the preheated group presented 100% for all properties. Four restorations had postoperative sensitivity at baseline for nonheated (11.4%) and five for preheated (14.2%), but the postoperative sensitivity scores were considered highly acceptable at 12-, 24-, and 36-months. Conclusions: After 36 months, preheated nanofilled RCs showed an acceptable clinical performance similar to that of the nonheated ones in class I restorations, but with better resistance to marginal staining.

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ObjectivesThis paper presents a systematic review and meta-analysis of the effect of preheating on the hardness of nanofilled, nanoceramic, nanohybrid, and microhybrid resin composites.Materials and MethodsAn electronic search of papers on MEDLINE/PubMed, ScienceDirect, and EBSCOhost was performed. Only in vitro studies were included. Non-English studies, case reports, clinical trials, and review articles were excluded. A meta-analysis of the reviewed studies was conducted to quantify differences in the microhardness of the Z250 microhybrid resin composite using the Comprehensive Meta-Analysis software.ResultsOnly 13 studies met the inclusion criteria for this systematic review. The meta-analysis showed that there were significant differences between the non-preheated and preheated modes for both the top and bottom surfaces of the specimens (p < 0.05). The microhardness of the Z250 resin composite on the top surface in the preheated mode (78.1 ± 2.9) was higher than in the non-preheated mode (67.4 ± 4.0; p < 0.001). Moreover, the microhardness of the Z250 resin composite on the bottom surface in the preheated mode (71.8 ± 3.8) was higher than in the non-preheated mode (57.5 ± 5.7, p < 0.001).ConclusionsAlthough the results reported in the reviewed studies showed great variability, sufficient scientific evidence was found to support the hypothesis that preheating can improve the hardness of resin composites.

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Objectives In the clinical medicine, immunosuppressive drugs are used for an assortment of disorders, while their effect on the pulp healing is a controversial issue. This study evaluated the effect of different immunosuppressive drugs on the healing capacity of mechanically exposed dogs' dental pulps after direct pulp capping (DPC) with calcium silicate-based cement. Materials and methods Twelve healthy male dogs were randomly allocated into four equal groups, 3 dogs each: group I allocated as a control group where no drugs were received; group П given prednisone (Pred); group III given a combination of Pred and cyclosporine A (CsA); and group IV given triple dose including Pred, CsA, and mycophenolate mofetil (MMF) for 45 days before the operative procedures and until the dogs were euthanized. In each dog, 16 class V cavities were prepared on the labial surfaces of anterior teeth. Following mechanical exposure, the pulps were capped with Biodentine, calcium silicate-based cement. The pulpal tissues response to Biodentine was assessed 65 days postoperatively. ResultsThe pulp healing response was inferior in the Pred-CsA-and Pred-CsA-MMF-treated groups compared with the control and Pred-treated groups (P < 0.05). Non-significant difference was found between control and Pred-treated groups (P > 0.05). Conclusions Within the limitation of this study, DPC with calcium silicate-based cement performed under strict aseptic condition for traumatically exposed dental pulp can be considered as a successful treatment option for those who receiving Pred immunosuppressive therapy. Meanwhile, DPC with those receiving a combination of Pred, CsA, and/or MMF immunosuppressive drug regimens demonstrated unfavorable results. Clinical relevance Direct capping of mechanically exposed pulps with calcium silicate-based cement performed with special care for preventing infection considered a suitable strategic measure for preserving pulp vitality in patients receiving corticosteroid immunosuppressive drug.

Background Corticosteroids are commonly used as a treatment for a variety of pathological conditions, however, systemic corticosteroid administration has adverse effects including impaired immune response and wound healing. Such complications may affect pulp healing after direct pulp capping. The current study evaluated the influence of corticosteroids on the healing ability of exposed dogs’ dental pulps after direct pulp capping (DPC) with bioactive materials. Methods Ten healthy male dogs were assigned randomly into two groups, 5 dogs each: group I represent the control group which did not receive any medication, and group II was given corticosteroid for 45 days before DPC and till the dogs were euthanized (n = 75 teeth for each group). Following mechanical exposure, the pulps were randomly capped with either Ca(OH)2, MTA, or Biodentine. The pulpal tissues’ reaction to the capping materials was evaluated 65 days postoperatively according to the following parameters: calcific bridge formation, pulpal inflammation, pulp necrosis, and bacterial infiltration. Results The corticosteroid-treated group revealed no significant difference compared to the control group concerning the pulp healing response (P > 0.05). Both Biodentine and MTA-treated specimens revealed significant differences with Ca(OH)2-treated specimens (P < 0.05) which displayed a superior positive effect of both MTA and Biodentine to Ca(OH)2 regarding all the parameters. Conclusions Direct pulp capping technique whenever indicated in subjects treated with corticosteroid immunosuppressive drugs like prednisone performed well in aseptic conditions especially when capped with bioactive materials.

Objective: To assess the influence of preheating on microhardness and surface roughness of nanoceramic resin composite.Methods: Forty disc-shaped specimens of nanoceramic resin composite Ceram X Duo (Dents ply De Trey, Konstanz, Germany) were made using a mold and then randomly assigned into two groups (with and without preheating where n=20). Each group was subdivided according to the test into two subgroups (n=10). Vickers hardness measurements for the top and bottom surfaces of the specimens were evaluated by tester machine and surface Roughness (Ra) was assessed using the Atomic Force Microscope.Results: Results of both tests showed no significant difference among specimens either preheated or not. Nevertheless, microhardness results revealed significant difference if top surfaces compared to the bottom ones either the specimens were preheated or not. Surface roughness results exhibited no significant difference among the preheated and non-preheated specimens. Conclusion:Preheating had a certain effect on the mechanical and surface properties of nanoceramic resin composite.

Background: The marginal integrity of resin composite restorations especially in class V cavities remains a challenge in operative dentistry. This study aimed to evaluate the effect of substrate and restorative system on the marginal adaptation of class V composite restorations. Methods: Standardized class V cavities were prepared in sound human molars with the cervical margin on dentin and the occlusal margin on enamel. An ormocer, nanofilled, nanoceramic and microhybrid composite were utilized. After finishing and polishing, marginal adaptation of the restorations was analyzed by metallographic microscope (T0) and the following parameters were recorded: width of maximum marginal gap (MG), percentage length of debonded margin relative to cavity periphery (DM), and marginal index (MI = MG × DM/100). After the first evaluation, the specimens underwent thermal cycling (2,000 cycles of 5ºC–55ºC ± 2ºC) and load cycling (50,000 cycles of 50 N and 1 Hz). Specimens were reanalyzed by metallographic microscope (T1). The recorded data were compared using multi-way analysis of variance (ANOVA) and Tukey’s test (ɑ < 0.05). Results: The type of restorative/adhesive system and margin location significantly affected marginal adaptation. Ormocer restorations exhibited the lowest MG, DM, and MI values, whereas microhybrid composite restorations exhibited the highest values. Relative to the baseline condition, the specimens showed higher gap measurements after thermal and load cycling. Conclusion: The margin location and restorative system have a substantial effect on the marginal adaptation of class V composite restorations. Clinical relevance statement:The cavity margin location and the restorative system have significant influence on the durability of cervical restorations.