“Effect of Hydroxyapatite Nanoparticles On Compressive strength and Flexural strength of Dental Composites Using Taguchi Method”

Several composite materials are being used in biomedical and dental field with their immense applications to repair and transform various organs in human body. Recent advances suggest that Hydroxyapatite is one of the most reliable and widely used inorganic composite in dentistry. Desirable applications of Hydroxyapatite are achieved by utilizing variety of hydroxyapatite and their composites. This study was conducted to evaluate the compressive & flexural strength. Cylindrical specimens (n=9) for compressive strength & rectangular shaped specimens (n=9) for flexural strength were made according to manufacturer’s recommendations. Dental composite is using quartz, silica, and alumina glass as filler for a long time. Taguchi optimization technique keeps the experimentation within limit giving valid product in the calculating of compressive and flexural strength optimization. The goal of the work is to detect the best combination of composite materials. Keywords: Hydroxyapatite, Compressive Strength, Flexural Strength, Taguchi’s optimization method.

Eugenyl-2-Hydroxypropyl Methacrylate-Incorporated Experimental Dental Composite: Degree of Polymerization and In Vitro Cytotoxicity Evaluation

The aim of this study was to evaluate the properties of new dental formulations containing eugenyl-2-hydroxypropyl methacrylate (EgGMA) monomer, as restorative dental material, in terms of their degree of photopolymerization and cytotoxicity. The target model composites (TBEg0, TBEg2.5, and TBEg5) were prepared by mixing 35% organic matrix (TEGDMA/BisGMA (50/50 wt%) of which 0, 2.5, and 5 wt%, respectively, were replaced with EgGMA monomer) with 65% filler (silanized hydroxyapatite (HA)/zinc oxide (ZnO2), 4:3 by weight). The vinylic double-bond conversion (DC) after light-curing was studied using Fourier transform infrared technique whereas cell viability was in vitro tested using primary human gingival fibroblasts cells over 7 days by means of AlamarBlue colorimetric assay. The obtained data were statistically analyzed using ANOVA and Tukey post-hoc tests. The results revealed no significant difference in DC between TBEg2.5 (66.49%) and control (TBEg0; 68.74%), whereas both differ significantly with TBEg5, likely due to the inhibitory effect of eugenol moiety at high concentration. The cell viability test indicated that all the composites are biocompatible. No significant difference was counted between TBEg2.5 and TBEg5, however, both differed significantly from the control (TBEg0). Thus, even though its apparent negative effect on polymerization, EgGMA is potentially safer than bisphenol-derived monomers. Such potential properties may encourage further investigations on term of EgGMA amount optimization, compatibility with other dental resins, and antimicrobial activity.

Fabrication, characterization, and optimization selection of ceramic particulate reinforced dental restorative composite materials

The objective of the article is to explore the fabrication of dental restorative composite materials and the ranking order using the preference selection index (PSI) as a multi criteria decision making (MCDM) technique under a set of conflict performance defining criteria (PDCs). The polymer matrix of the dental restorative composite was prepared using bisphenol a-glycidyl methacrylate (55 wt.%), triethylene glycol dimethacrylate (44 wt.%), camphorquinone (0.3 wt.%), and ethyl 4-(dimethylamino) benzoate (0.7 wt.%). Five different dental restorative composite material compositions were fabricated using hybrid nSiO2-TiO2 particulates with a variation of nSiO2 (0, 2, 4, 6, 8 wt.%) while TiO2 is constant (15 wt.%). The results revealed that an increasing trend has been found in compressive strength, flexural strength, Vickers hardness, etc., while a decreasing trend has been shown in depth of cure, polymerization shrinkage, degree of conversion etc. The performance analysis of five dental composite formulations via the PSI method shows the following ranking order: nS4 > nS6 > nS2 > nS0 > nS8. The obtained experimental results are associated with the ranking order of the different sets of dental composite formulations. Hence, the preference selection index approach is one of the best techniques among MCDM techniques for ranking under different PDCs.

Evaluation of the Effect of Cold Plasma Treatment on the Microshear Bond Strength of Composite Resin Restorations to Dentin using Different Adhesive Systems and the Effect of Thermocycling

Introduction: Currently, non-thermal plasma is used to modify the enamel and dentin surfaces to improve the bonding surface to dental composite resins. Non-thermal plasma creates a hydrophilic surface, decreases the contact angle, and improves the bonding quality. The present study aimed to evaluate the microshear bond strength (µSBS) of composite resins to dentin using different adhesive systems. Materials and Methods: Bovine incisor teeth were randomly assigned to three groups of G-Premio, Clearfil SE Bond, and Adper Single Bond adhesive groups after preparation. Each group was divided into two subgroups in terms of argon plasma surface preparation, and each subgroup was divided into two groups in terms of thermocycling (n=12). The microshear bond strength of the samples was determined using a universal testing machine. Three-way ANOVA was used to analyze the effect of the adhesive, plasma preparation, and thermocycling. Post hoc Tukey tests were used for two-by-two comparisons of µSBS. Statistical significance was set at P <0.05. Results: The results of the µSBS test showed that the application of plasma resulted in a significant increase in the mean µSBS in the G-Premio group, with no significant increase in the Clearfil SE bond and Adper Single groups. The effect of thermocycling after plasma application was significant only in the Adper Single group. Conclusion: The application of plasma might increase the bond strength of composite resins to dentin. However, further studies are necessary.

Effect of Volume and Renewal of the Storage Media on the Release of Monomer from Dental Composites

This study evaluated the effect of the volume and renewing of storage media on monomer leachability from dental composite. Samples of two dental composites (BEAUTIFIL II Gingiva (BG) and Filtek Bulk-Fill Flowable (FBF)) were stored after polymerization in 1 and 3 milt storage media (ethanol/water 75%) for seven days. Refreshing of storage media was done in half of the samples of each group. The amounts of releasing monomers (UDMA, BisGMA, TEGDMA) in storage media were measured by high-performance liquid chromatography (HPLC). Data was analyzed using two-way ANOVA and t-test (α = 0.05). Elution of TEGDMA and UDMA from both composites was significantly higher in 3 mL storage media. In groups with refreshing of storage media, BisGMA had higher amounts of release. Saturation makes the storage media volume important factor in monomer elution. Refreshing of storage media had significant effect on monomer release before the elution of 50% of total released monomer.

The influence of accelerated aging on the physical and chemical properties of a composite material: a systematic overview

Relevance. Today, dental composite materials are very popular among dentists. The composite material is a filler in the form of particles of various sizes immersed in a polymer matrix. Polymer composites are used for direct filling of all groups of teeth and at different depths of the lesion. Composite materials have optimum mechanical, aesthetic and functional properties. They are simple and easy to use, provide long-term restoration service, and also have a wide price range. All these qualities allowed composite materials to firmly gain a foothold in the practice of dentists around the world. In this regard, clinicians and researchers are constantly trying to significantly improve their physical, mechanical, adaptive and aesthetic properties.Aim. Conduct a systematic assessment of the available scientific data on the effect of accelerated aging of the composite on its physicochemical properties.Materials and methods. In the course of a systematic review of the literature, a study was made of publications in electronic databases such as Google Scholar, PubMed, Research gate, Elibrary. The search results are formatted using the Prisma diagram.Results. Dental composites inevitably age over time and under the influence of environmental factors. To predict the long-term service life of composite restorations, scientists and clinicians are studying the aging behavior of the material. To simulate the clinical conditions of the oral cavity, various methods of artificial aging of dental composite materials have been developed.Conclusions. A study of scientific papers published over the past 10 years on the topic of artificial aging of dental composite materials has shown its unambiguous effect on the mechanical and morphological properties of polymers. The use of methods for simulating clinical conditions made it possible to reduce the study time and analyze the changes obtained.

Dental Composite Restorations Repair: A Systematic Review and Meta-analysis

Background: Controversy exists in the literature regarding the most optimal repair procedure for improving the adhesion between the repair resin and the existing resin composite materials. Hence the aim of the present study was to do a systematic review and to analyze the adhesion potential of resin-based composites to similar and dissimilar composites and aimed to determine the possible dominant factors affecting the bond strength results. Materials & Methods: Randomized clinical trials (RCTs) and prospective cohort design were searched through electronic databases including MEDLINE, PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials for randomized clinical trials (RCTs) until July 2020 that compared different methods of composite restoration repair and a minimum mean follow-up time of 1 year. There were no restrictions on a particular treatment indication or outcome measures. Two authors independently conducted screening, risk of bias assessment, and data extraction of eligible trials in duplicate. We applied the Cochrane risk of bias assessment tool to consider the risk of bias. Results: We identified 10 articles; two of them were RCTs, and eight prospective cohort studies. There were 530 participants, with 990 teeth, dealing with resin-based composite (RBC) restorations. The intervention of defective restorations ranged from minimal intervention to total restoration replacement. The evaluation criteria were also varied with different evaluation protocols. The low number and heterogeneity of RCTs did not allow for meta-analyses. Conclusions: Although different repair protocols are mentioned in the literature according to the included studies, an appropriate and definitive conclusion can't be drawn. However, it seems repairs versus replacements should be considered as the first line of treatment when all factors lead to repair rather than replacement. Further randomized controlled trials with high methodological quality need to be conducted in order to establish evidence-based recommendations, particularly for RBC repair.

CLOSURE OF MIDLINE DIASTEMA BY DIRECT COMPOSITE RESIN BUILD-UP USING PUTTY INDEX- A CASEREPORT

A common aesthetic concern among patient is maxillary anterior space or diastema. Labial frenulum, microdontia, mesiodens, peg-shaped lateral incisors, agenesis, cysts, habits such as finger sucking, tongue thrusting, or lip sucking, dental malformations, genetics, proclinations, dental-skeletal discrepancies, and imperfect coalescence of the interdental septum are some of the causes of midline diastema. For diastema closure there are a variety of therapy options. Many novel therapies have been applied, ranging from restorative procedures to surgery (frenectomies) and orthodontics for closure of diastema or a combination of procedures to meet the aesthetic and functional needs of patient’saesthetic. Recent advancement in direct dental composite resin allows dentists to do minimally invasive cosmetic dentistry that is both conservative and time-consuming. In diastema cases, direct composite resins give the dentist and patient entire control over the restriction and the construction of a natural smile. The purpose of this study is to present a case report of aesthetic management using putty index of maxillary anterior space, which includes the midline.