The aim of the study was to investigate the temperature rise of a nanocomposite and a conventional hybrid dental composite during photopolymerization when cured with halogen curing lamp (QHT) and light-emitting diode (LED). Temperature rise during photopolymerization of two commercially available composites (Filtek Supreme(R) and TetricCeram) were measured using a K-type thermocouple and a digital thermometer. Different curing modes were utilized to cure the composites: a high-intensity QHT unit (Optilux 501) in two different modes (standard and ramp), a low-intensity QHT unit (Coltolux 50), and an LED unit (Ultralume-2). Total temperature rise, polymerization reaction exotherm, and irradiation-induced temperature rise of the composites were determined. Degree of conversion of the specimens was measured using FTIR spectroscopy. The results revealed that the Filtek Supreme nanocomposite showed lower temperature rise and degree of conversion in comparison with the hybrid composite (p < 0.05). It was also found that the LED curing unit induced considerable total and irradiation temperature rise without any improvement in the degree of conversion. Ramp curing mode showed lower temperature rise and delayed gel point and was found to be more effective than QHT standard mode and LED units. Although it is claimed that the LED curing units exhibit lower temperature rise during the photopolymerization, the present study showed that the curing units have no advantage over the conventional QHT units regarding the temperature rise and degree of polymerization conversion.

This case report describes a restorative procedure for immediate tooth replacement using a natural tooth pontic and fiber-reinforced composite following extraction in an area of severe localized bone loss. SUMMARYThe loss and replacement of anterior maxillary teeth poses several challenges. In patients refusing implant surgery, when minimal tooth reduction is desired, a fiber-reinforced composite fixed-partial denture may be used as a conservative alternative to a conventional fixed-partial denture for replacement of a single missing tooth. This article describes a clinical technique and six-year follow-up. The patient presented with a missing maxillary central incisor due to localized juvenile periodontitis. The abutment teeth were clinically stable. The advantage of supragingival margins and minimal tooth structure removal made the bonded bridge with a natural tooth pontic a viable procedure for this compromised restorative situation.

This study aimed to evaluate the effect of photobiomodulation therapy (PBMT) with 915 nm wavelength on pain reduction during maxillary incisors' local infiltration in a randomized clinical trial study. A prospective triple-blinded split-mouth clinical trial was designed to assess pain perception during needle insertion and local anesthetic injection in 32 healthy patients required operative caries management on contralateral maxillary incisors. After laser treatment (915 nm, power of 1.5 W, duty cycle of 60% and energy density of 72 J cm À2 ) in active group and no irradiation in sham group, the injection was performed. Patients' perception of pain was immediately assessed using numerical rating scale (NRS) for pain. Washout period between two appointments was one week. Wilcoxon signed-rank and Pearson correlation statistical analyses were used to assess the comparison of pain score between two appointments and the effect of anxiety level of previous dental injections. The mean scores of pain for the active laser and sham laser groups were 2.5 AE 2.19 and 4.34 AE 2.52, respectively, with a statistically significant higher NRS in the sham laser group (P ˂ 0.05). In this study's condition, diode PBMT reduced pain during infiltration on maxillary incisors. Anxiety experience of dental injection had no significant effect on pain perception scale (P ˃ 0.05).

Please cite this article as follows: Motevasselian F, Amiri Z, Chiniforush N, Mirzaei M, Thompson V. In vitro evaluation of the effect of different surface treatments of a hybrid ceramic on the microtensile bond strength to a luting resin cement. Abstract Introduction:The aim of the present study was to investigate the effect of different surface treatments of a hybrid ceramic, Vita Enamic, on the micro-tensile bond strength (µ-TBS) to resin cement. Methods: Ten blocks (3×10×8 mm) were retrieved from the original blocks and divided into 5 groups according to the different surface treatments performed: Groups 1: 35% acid phosphoric for 60 seconds (PA); group 2: Sandblasting with 50 µm Al 2 O 3 particles for 10 seconds (SB); groups 3: 9.5% hydrofluoric acid for 60 seconds (HF), group 4: The Er:YAG laser (2 W, 10 Hz) (ER1), group 5: The Er:YAG laser (3 W, 10 Hz) (ER2). All treated surfaces were salinized and the blocks with similar surface treatments were bonded together using a dual-cured resin cement and light-cured. After 24-hour storage in water, the blocks were cut into beams (1 mm 2 ). Half of the specimens in each group (n=16) were tested immediately and the rest were subjected to thermocycling between 5°C and 55°C for 6000 cycles before the µ-TBS test at a crosshead speed of 0.5 mm/min. The data were analyzed using two-way analysis of variance (ANOVA) and Tukey HSD tests and the significance level was set at 0.05. The failure mode was evaluated by using a stereomicroscope. Results: The µ-TBS was clearly influenced by surface treatment methods (P < 0.001) and thermocycling significantly decreased the bond strength values in all groups (P = 0.007). The highest value (66.07 MPa ± 11.3) was obtained for the HF groups with no thermocycling and the lowest values were observed in the laser groups with no significant difference among different irradiation parameters. Adhesive failure was mainly observed in the PA and SB groups while mixed failure was predominantly shown in the laser and HF groups. Conclusion: This study demonstrated that surface treatment of VE with HF and salinization could improve the bond strength to a dual-cured resin cement, and Er:YAG laser irradiation with the evaluated parameters did not promote the adhesion of the resin cement to VE.

Aim: To compare the microleakage of Cention N, a subgroup of composite resins with a resin-modified glass ionomer (RMGI) and a composite resin. Methods: Class V cavities were prepared on the buccal and lingual surfaces of 46 extracted human molars. The teeth were randomly assigned to four groups. Group A: Tetric N-Bond etch-and-rinse adhesive and Tetric N-Ceram nanohybrid composite resin, group B: Cention N without adhesive, group C: Cention N with adhesive, and group D: Fuji II LC RMGI. The teeth were thermocycled between 5°-55°C (×10,000). The teeth were coated with two layers of nail vanish except for 1 mm around the restoration margins, and immersed in 2% methylene blue (37°C, 24 h) before buccolingual sectioning to evaluate dye penetration under a stereomicroscope (×20). The data were analyzed by the Kruskal-Wallis and Wilcoxon tests (α=0.05). Results: Type of material and restoration margin had significant effects on the microleakage (p<0.05). Dentin margins showed a higher leakage score in all groups. Cention N and RMGI groups showed significant differences at the enamel margin (p=0.025, p=0.011), and for the latter group the scores were higher. No significant difference was found at the dentin margins between the materials except between Cention N with adhesive and RMGI (p=0.031). Conclusion: Microleakage was evident in all three restorative materials. Cention N groups showed similar microleakage scores to the composite resin and displayed lower microleakage scores compared with RMGI.