The aim was to evaluate the effects of fiber-reinforced composite restorations and a bulk-fill resin composite on the fracture strength of mandibular premolars treated endodontically. Standard mesio-occluso-distal (MOD) cavities were prepared in 48 mandibular premolars. Following root canal treatment, teeth were assigned to four groups: Group 1, nano-hybrid resin composite; Group 2, polyethylene woven fiber plus nano-hybrid resin composite; Group 3, short fiber-reinforced resin composite plus nano-hybrid resin composite; and Group 4, bulk-fill resin composite plus nano-hybrid resin composite. Then, the teeth were subjected to the fracture toughness test. The data were analyzed statistically using one-way ANOVA, followed by Tukey's post-hoc test. The fiber-reinforced groups had better results than the nano-hybrid and bulk-fill composites (p<0.05), while the bulk-fill and nano-hybrid composite restorations gave similar results (p>0.05). Fiber-reinforcement improved the fracture strength of teeth with large MOD cavities treated endodontically. Bulk-fill composites can be used reliably as well as nano-hybrid composites.

Reduced-step systems used after a prepolisher can be an acceptable alternative to multiple-step systems on enhancing the surface smoothness of a nanohybrid composite; however, their effectiveness depends on the materials' properties. (J Esthet Restor Dent 29:31-40, 2017).

Objective:To compare the performance and postoperative sensitivity of a posterior resin composite with that of bonded amalgam in 40 (n = 20) large sized cavities and to evaluate whether resin composite could be an alternative for bonded amalgam.Materials and Methods:This was a randomized clinical trial. Twenty patients in need of at least two posterior restorations were recruited. Authors randomly assigned one half of the restorations to receive bonded amalgam and the other half to composite restorations. Forty bonded amalgams (n = 20) and composites (n = 20) were evaluated for their performance on modified-US Public Health Service criteria and postoperative sensitivity using visual analogue scale (VAS) for 36-months.Results:Success rate of this study was 100%. First clinical alterations were rated as Bravo after 1 year in marginal discoloration, marginal adaptation, anatomical form, and surface roughness for both amalgam and composite. At the 3rd year, overall “Bravo” rated restorations were 12 for bonded amalgam and 13 for resin composites. There were no significant differences among the VAS scores of composites and bonded amalgams for all periods (P > 0.05) except for the comparisons at the 3rd year evaluation (P < 0.05).Conclusions:Within the limitation of this study, both resin composite and bonded amalgam were clinically acceptable. Postoperative sensitivity results tend to decrease more in composite restorations rather than amalgams. Therefore, it was concluded that posterior resin composite can be used even in large sized cavities.

BackgroundTopical fluoride agents have been shown to be the most effective method in treating demineralized enamel after in-office bleaching treatments. Thus, this study aimed to examine the effects of two different post-bleaching fluoridation agents: 1.5% titanium tetrafluoride (TiF4) (9200 ppm) and 2.1% sodium fluoride (NaF) (9500 ppm), on the calcium loss of enamel after an acidic challenge.MethodsTen maxillary premolars were sectioned into four pieces and then divided into the following four groups: Group 1: Control, kept in artificial saliva, no treatment; Group 2: 38% hydrogen peroxide (HP); Group 3: 38% HP followed by 1.5% TiF4; Group 4: 38% HP followed by 2.1% NaF solution. The specimens were subjected to demineralization for 16 days, refreshing the solution every 4 days; that is, on the 4th, 8th, 12th, and 16th days. Calcium ion (Ca2+) concentration was determined by an atomic absorption spectrophotometer. Data were analyzed using Friedman and Wilcoxon tests (p = 0.05).ResultsThe loss of Ca2+ in each of the test groups was compared with that of the control group, depicting that there was a statistically significant difference among the groups after 4, 8, 12, and 16 days and in total (p < 0.05). The calcium released from the fluoride-applied groups was lower when compared with the 38% HP and control group. At the end of the 16th day, the total amount of calcium released from the TiF4-treated samples (9.12 mg/mL) was less than from the NaF-treated samples (13.67 mg/mL) (p < 0.05).ConclusionsRegarding the results of our in vitro study, the risk of further demineralization was significantly reduced with the use of TiF4 and NaF after bleaching with 38% HP. TiF4was found to be more effective in preventing Ca2+ release owing to acid attack when compared with NaF. In the case of an intra-oral acidic exposure, the use of topical 1.5% TiF4 and 2.1% NaF agents might be beneficial after bleaching with 38% HP.