Two­year clinical performance of indirect restorations fabricated from CAD/CAM nano hybrid composite versus lithium disilicate in mutilated vital teeth. A randomized controlled trial.

TRIAL DESIGN: This is a randomized, controlled, superiority, double-blinded, parallel-group, two-arms trial with an allocation ratio of 1:1. The aim of this trial was to compare the two-year clinical performance of partial indirect restorations fabricated from CAD/CAM nano-hybrid composite and ceramic lithium disilicate blocks using the modified USPHS criteria. METHODS: In two parallel groups (n = 50 restorations), fifty participants having mutilated vital teeth with a minimum of two remaining walls were randomly enrolled in this trial and received indirect restorations of either nano-hybrid composite resin blocks (Brilliant, Coltene, Switzerland) or Lithium Disilicate (IPS Emax CAD). The restorations were assessed using modified USPHS criteria by two independent blinded assessors at baseline, six months, one-year and two years follow-up visits. Categorical and ordinal data were presented as frequencies and percentages. Categorical data were analyzed using the chi-square test. Ordinal data were analyzed using the Mann-Whitney U test for intergroup comparisons and Freidman's test followed by the Nemenyi post hoc test for intragroup comparisons. Numerical data were presented as mean and standard deviation values. They were analyzed for normality using the Shapiro-Wilk test. Data were found to be normally distributed and were analyzed using the independent t-test. The significance level was set at p ≤ 0.05 within all tests. RESULTS: Forty-eight participants received the allocated intervention and completed the follow-up periods. There was a statistically significant difference between both tested materials for all USPHS criteria regarding Marginal integrity and Marginal discoloration at six-months Follow-up, but with no statistically significant difference at one- and two-year follow-up. CONCLUSIONS: Both materials showed an acceptable, successful clinical performance along the two-years follow-up period. CLINICAL RELEVANCE: The CAD/CAM nano-hybrid composite blocks are as reliable as Lithium disilicate for restoring mutilated vital teeth.

Effect of the application of a hydrogen peroxide home bleaching agent on the cytotoxicity of different CAD-CAM restorative materials.

BACKGROUND: The information regarding the cytotoxicity of ceramic and resin-matrix ceramic materials subjected to over-the-counter bleaching agents is limited in the literature. OBJECTIVES: The aim of the present study was to investigate the cytotoxic effects of lithium disilicate ceramic (LDC), resin nano-ceramic (RNC) and nano-hybrid composite (NHC) computer-aided design/ computer-aided manufacturing (CAD-CAM) block materials subjected to a home bleaching agent and artificial saliva. MATERIAL AND METHODS: A total of 432 specimens were prepared from 3 different CAD-CAM materials. Each material group was divided into 4 groups according to the storage medium (phosphate-buffered saline (PBS) or artificial saliva), and whether the specimens were subjected to a bleaching agent or not. For the bleached groups, hydrogen peroxide (10%) was applied to the specimens for 30 min/day for 15 days, and the specimens were immersed in PBS or saliva after bleaching. The viability of epithelial cells was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at the end of the 5th, 10th and 15th day of the study. The data was statistically analyzed. RESULTS: Regardless of the storage medium and the time period, all restorative materials decreased the viability of cells. The highest cytotoxicity levels were determined on the 15th day of the study. The application of a bleaching agent increased the cytotoxicity of the LDC specimens stored in artificial saliva. The RNC material stored in PBS demonstrated significantly higher cell viability than the LDC and NHC groups. The LDC and RNC specimens stored in artificial saliva did not show any significant difference in cytotoxicity. When the materials were subjected to bleaching, NHC demonstrated the highest cytotoxicity during all periods. No significant difference was found between the LDC and RNC specimens subjected to both artificial saliva and bleaching in terms of cytotoxicity. CONCLUSIONS: The type of restorative material, the immersion medium, the application of a bleaching agent, and the application period affected the cytotoxicity of the materials. Over-the-counter home bleaching agents may induce cellular cytotoxicity due to the existing restorations, and patients should be informed about this potential biological response.

Comparative evaluation of the effect of adhesive restorative composite resins on the reinforcement of peri-cervical dentin: An in vitro study.

Background: Peri-cervical dentin (PCD) and its reinforcement play a crucial role in the fracture resistance of root canal-treated teeth. Aims: The aim of this study was to compare the fracture resistance of dual-cure, nano-hybrid, and short-fiber reinforced composite resins restored PCD with conventional hybrid composite (CHC) resin restored endodontically treated mandibular premolars. Settings and Design: Academic, in vitro study. Materials and Methods: The prepared mandibular premolar samples were randomly divided into five groups of 10 each. In Group 1, teeth were left intact. The remaining 40 teeth were endodontically treated and obturated as follows: In Group 2, teeth were obturated with gutta-percha till cementoenamel junction and restored with CHC. Teeth in Groups 3, 4, and 5 were obturated to a depth of 5 mm from the cervical line and restored with dual-cure, nano-hybrid, and short-fiber reinforced composite resins, respectively. Fracture resistance was tested using a universal testing machine. Statistical Analysis Used: One-way analysis of variance and post hoc Tukey's test. Results: Short-fiber reinforced composite resin showed a significantly higher mean fracture resistance value compared with other experimental groups. The mean fracture resistance values were obtained as Group 1 > Group 5 > Group 4 > Group 3 > Group 2. Conclusions: Reinforcement with short-fiber reinforced composite showed significantly higher fracture resistance compared with nano-hybrid and dual-cure composite resins.

Comparative evaluation of mechanical and physical properties of a new bulk-fill alkasite with conventional restorative materials.

PURPOSE: The physical and mechanical performance of a newly commercialized dental restorative material (alkasite) was compared with glass ionomer cement (GIC) and nano-hybrid composite. METHODOLOGY: Human extracted premolars were used to investigate the shear bond strength. Restorative materials were placed on the dentine surface and were aged in deionized water for 14 days. The 3-D surface roughness was evaluated before and after chewing simulation cycles (50,000). The samples were fatigued mechanically using a chewing simulator and investigated with a scanning electron microscope (SEM). RESULTS: For shear bond strength, alkasite showed significantly high values than GIC, whereas non-significant difference was observed between alkasite and nano-hybrid composite. After the chewing simulation (50,000 cycles), non-significant difference was found between GIC and nano-hybrid composite, where surface roughness values were highest for GIC and lowest for alkasite. CONCLUSION: The newly developed restorative material (alkasite) has shown better results than existing restorative materials.

Influence of modeling agents on the surface properties of an esthetic nano-hybrid composite.

OBJECTIVE: The aim of this study was to evaluate the influence of different modeling agents on the surface microhardness (Vickers hardness number; VHN), roughness (Ra), and color change (ΔE) of a nano-hybrid composite with or without exposure to discoloration by coffee. MATERIALS AND METHODS: Sixty-four cylinder-shaped nano-hybrid composite specimens were prepared using a Teflon mold. The specimens' surfaces were prepared according to the following groups: group 1, no modeling agent; group 2, Modeling Liquid; group 3, a universal adhesive (G-Premio Bond); and group 4, the first step of a 2-step self-adhesive system (OptiBond XTR). Specimens were randomly allocated into 2 groups (n = 8) according to the storage medium (distilled water or coffee). VHN, Ra, and ΔE were measured at 24 hours, 1 week, and 6 weeks. The Kruskal-Wallis test followed by the Bonferroni correction for pairwise comparisons was used for statistical analysis (α = 0.05). RESULTS: Storage time did not influence the VHN of the nano-hybrid composite in any group (p > 0.05). OptiBond XTR Primer application affected the VHN negatively in all investigated storage medium and time conditions (p < 0.05). Modeling Liquid application yielded improved Ra values for the specimens stored in coffee at each time point (p < 0.05). Modeling Liquid application was associated with the lowest ΔE values in all investigated storage medium and time conditions (p < 0.05). CONCLUSION: Different types of modeling agents could affect the surface properties and discoloration of nano-hybrid composites.

An in vitro comparative evaluation of commonly consumed catechu and catechu with lime on surface roughness and color stability of the conventional nano-hybrid composite.

AIM: Comparative evaluation of commonly consumed catechu and catechu with lime on surface roughness and color stability of the conventional nano-hybrid composite. METHODOLOGY: A total of 50 uniform cylindrical disks of 10-mm diameter and 2-mm thickness prepared from the nano-hybrid composite were used in the study. Each sample was randomly divided into three subgroups of 20 samples each in two experimental groups (catechu, catechu, and lime) and 10 samples in the control group (artificial saliva). The samples were immersed in each agent for 15 days. Surface roughness and color changes measurements were noted at the baseline and 15th day by two-dimensional profilometer and spectrophotometer, respectively. RESULTS: It was found that nano-hybrid composite resin showed more surface roughness and color change when immersed in catechu and catechu with lime as compared to the control group. Intergroup comparison showed statistical significant increase in surface roughness and color change in the catechu group followed by the catechu with the lime group and artificial saliva. CONCLUSION: Within the limits of the present study, it can be concluded that all experimental specimens showed discoloration. At the end of 15th day, among the groups, catechu showed more surface roughness and color change followed by the catechu and lime and the control group.

A comparative in vitro study on fluoride release and water sorption of different flowable esthetic restorative materials.

OBJECTIVES: The objective of the study was to evaluate fluoride release and water sorption of three flowable esthetic restorative materials: a giomer, a fluoride-releasing resin composite, and a nonfluoridated resin composite. MATERIALS AND METHODS: Ten samples from a giomer, a fluoride releasing nano-hybrid, and a nonfluoridated nano-hybrid composite were prepared and immersed in deionized water. Fluoride measurements were done using an ion-specific electrode attached to a microprocessor-based fluoride meter after 1 day, 1 week, and 4 weeks. Another thirty samples were made and placed in desiccators. Water sorption was calculated by weighing the specimens before and after water immersion for 1 day, 1 week, and 4 weeks. Data analysis was done using two-way ANOVA, paired t-test (P < 0.05), and Pearson's correlation coefficient to calculate correlations between fluoride release and water sorption. RESULTS: The highest fluoride release was from giomer after 1 day, it was statistically significant from all other groups. Both nano-hybrid composites after 1 day showed significantly lower water sorption which was different than all the other groups. Pearson's correlation showed no significant correlations between fluoride release and water sorption. CONCLUSIONS: Fluoride release is material and time dependent, while water sorption is material dependent.

Rapid ionic liquid-supported nano-hybrid composite reinforced hollow-fiber electromembrane extraction followed by field-amplified sample injection-capillary electrophoresis: An effective approach for extraction and quantification of Imatinib mesylate in human plasma.

The focus of this study is development of a new, convenient, rapid and sensitive electromembrane extraction approach (based on an ionic liquid-supported MWCNTs/ZnO reinforced hollow fiber, for the first time) as an off-line sample clean-up/preconcentration method coupled with capillary electrophoresis (CE-UV) using field-amplified sample injection (FASI) for quantification of Imatinib mesylate in human plasma. The nano-hybrid sorbent, coated by 1-octyl-3-methylimidazolium bromide ionic liquid ([OMIm]Br) in this research, was prepared by a feasible basic catalyzed sol-gel method. Then, it was immobilized (supported by capillary forces and sonication) in pores of a segment of a polypropylene hollow fiber membrane as the extraction unit after dispersing in 2-nitrophenyl octyl ether (NPOE) solvent and subsequently served as the supported liquid membrane (SLM) composition. Significant variables affecting the proposed method were evaluated and optimized to achieve the maximum extraction performance. Optimal conditions were obtained by NPOE with 4mgmL-1 nano-sorbent as the SLM composition, 105V as the driving force, pH 2 and 1.8 of the donor and acceptor phases, respectively, an extraction time of 15min and an agitation rate of 800rpm. The developed method was validated according to FDA guidelines. Regarding the validation results, the method is proved to be linear (R2=0.998) over concentrations ranging from 25 to 1500ngmL-1 (LOD=6.24ngmL-1). The mean RSD values for intra- and inter-day precision studies were 6.83 and 7.71%, respectively and the mean recoveries ranged between 98 and 106%. Finally, the validated method was successfully applied for sensitive, selective and rapid determination of Imatinib in patient's plasma samples.

Two-year clinical comparison of a flowable-type nano-hybrid composite and a paste-type composite in posterior restoration.

AIM: The purpose of the present study was to compare the clinical efficacy between a flowable-type nano-hybrid composite and a paste-type composite for posterior restoration. METHODS: Of 62 posterior teeth in 33 patients (mean age: 34.1 years), 31 were filled with a paste-type composite (Heliomolar [HM] group), and another 31 with a flowable nano-hybrid composite (MI FIL [MI] group). Clinical efficacy was evaluated at 2 years after the restoration. RESULTS: There were no differences for retention, surface texture deterioration, anatomical form change, deterioration of marginal adaptation, and secondary caries, while a statistical difference was found for marginal discoloration, which was significantly greater in the HM group (P < 0.05). Furthermore, color matching in the MI group was superior to that in the HM group immediately after the restoration throughout the study period. CONCLUSIONS: The present 2-year clinical evaluation of different composites showed that the flowable nano-hybrid composite could be an effective esthetic material for posterior restoration.