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Background: Resin-based materials are the popular restorative material in dentistry. The majority of these materials are light cured with a major disadvantage: marginal leakage. Objective: To evaluate the gap width of different resin-based materials at the cervical dentin when achieved mechanical force. Methods: Class II cavities were prepared on extracted premolar teeth with the gingival margin 1 mm below the Cementoenamel Junction (CEJ). In the first three experimental groups, three different lining materials (flowable resin composite, bulk-fill flowable resin composite, and resin-modified glass ionomer cement) were placed at the cervical dentin with a thickness of 1 mm. The rest of the cavities were restored with conventional resin composite. The other two groups were restored with conventional resin composite (control) or high viscosity bulk-fill resin composite, respectively. All groups were thermocycled and underwent vacuum pressure 2.6 KPa for 30 min in a Scanning Electron Microscope (SEM). Results: There was no gap formation at the cervical dentin on the external surface when restored with high-viscosity bulk fill resin composite. Almost all gaps occurred at the interface between restorative materials and the hybrid layer. The flowable bulk fill resin composite showed a significantly smaller gap width on both the external and internal surfaces compared to the other groups (p< 0.05). The resin-modified glass ionomer cement showed the largest gaps in the cervical dentin (p < 0.05). Conclusion: The different types of resin-based materials demonstrated a different failure of gap width under mechanical force. It clearly occurred at the restorative material-hybrid layer interface.

Streptococcus mutanspredominantly creates an acidic environment in an oral cavity. This results in dental demineralization and carious lesions. The probiotics are beneficial microorganisms that modulate the bacterial balance in the digestive system. Prebiotics are defined as nondigestible oligosaccharides that are utilized for the selective stimulation of the beneficial microorganisms. The objective of this study was to evaluate the efficacy of the prebiotics, galactooligosaccharides (GOS) and fructooligosaccharides (FOS), for enhancing the probioticLactobacillus acidophilusATCC 4356, for inhibitingStreptococcus mutans(A32-2) for the prevention of dental caries. The growth rate of theS. mutanssignificantly decreased when cocultured withL. acidophilusin the GOS-supplemented medium at 3%, 4%, and 5%. In the FOS-supplemented medium, the growth rate ofS. mutanssignificantly decreased in all concentrations when cocultured withL. acidophilus. There was no significant difference in the growth rate ofL. acidophilusin all concentrations of either GOS or FOS. It can be concluded that the growth rate ofS. mutanswas significantly retarded when cocultured withL. acidophilusand the proper concentration of prebiotics. These prebiotics have potential for a clinical application to activate the function of the naturally intraoralL. acidophilusto inhibitS. mutans.

Dental materials have been continuously developing over a long period of time. Every effort has been made to develop the physical and mechanical properties of the materials to mimic the natural tooth substances. However, that has not yet been achieved, making it necessary to apply conservative dental treatments. Conservative treatments are procedures which minimize the amount of defective tooth structure removed while maximizing the remaining amount of intact tooth structure, and defining the margin of the restoration at the supragingival level. In a substantially destructed tooth, the direct restoration, which is the most conservative restoration, has the limitations on the retention or creation of the proper contour of the restoration. The indirectly partial coverage restoration has recently gained in popularity. This treatment preserves the tooth structure while allowing reconstruction of the destructed structure to enable correct and proper tooth functioning and also provides a satisfactory cosmetic appearance. The purpose of this paper is to review and compare the various conservative techniques of partial coverage restorations and the full coverage treatment with crowns.

Objective: Testing of methods to enhance the shear bond strength (SBS) between orthodontic metal brackets and amalgam by sandblasting and different primers. Materials And Methods: Three hundred samples of amalgam restorations (KerrAlloy®) were prepared in self-cured acrylic blocks, polished, and divided into two groups: nonsandblasted and sandblasted. Each group was divided into five subgroups with different primers used in surface treatment methods, with a control group of bonded brackets on human mandibular incisors. Following the surface treatments, mandibular incisor brackets (Unitek®) were bonded on the amalgam with adhesive resin (Transbond XT®). The SBS of the samples was tested. The adhesive remnant index (ARI) and failure modes were then determined under a stereo-microscope. Two-way analysis of variance, Chi-square, and Kruskal–Wallis tests were performed to calculate the correlations between and among the SBS and ARI values, the failure modes, and surface roughness results. Results: There were statistically significant differences of SBS among the different adhesive primers and sandblasting methods (P < 0.05). The sandblasted amalgam with Assure Plus® showed the highest SBS (P < 0.001). Samples mainly showed an ARI score = 1 and mix-mode failure. There was a statistically significant difference of surface roughness between nonsandblasted amalgam and sandblasted amalgam (P < 0.05), but no significant differences among priming agents (P > 0.05). Conclusions: Using adhesive primers with sandblasting together effectively enhances the SBS between orthodontic metal brackets and amalgam. The two primers with the ingredient methacryloxydecyl dihydrogen phosphate (MDP) monomer, Alloy Primer® and Assure Plus®, were the most effective. Including sandblasting in the treatment is essential to achieve the bonding strength required.