Antibacterial Dental Resin Composites: A Narrative Review

Lack of antibacterial properties in resin-based composites (RBCs) is one of the flaws that cause the failure of filling clinically. Several agents have been incorporated to endow RBCs with antibacterial properties. In this review, we summarize the recent antibacterial agents between 2015 and 2020 using keywords of antibacterial or antimicrobial dental resin composites by PubMed databases. The most effective strategies are concerned with polymerizable monomers (50%), followed by filler particles (39%) and leachable agents (11%). A recent modification of the antibacterial agent is either by combining two agents from the same category or mixing agents from different categories in one. More than two methods were used in one study to assess antibacterial efficacy. The most common method was biofilm colony-forming units (CFUs) counting method (40%), followed by live/dead bacteria staining assay of biofilms (25%), metabolic activity assay of biofilms using MTT assay (16%), lactic acid production assay of biofilms (8%), agar diffusion test (8%), and other methods (3%) such as minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC).

Urchin-like multiscale structured fluorinated hydroxyapatite as versatile filler for caries restoration dental resin composites

Caries is one of the most prevalent human diseases,resulting from demineralization of tooth hard tissue caused by acids produced from bacteria,and can progress to pulpal inflammation.Filling restoration with dental resin composites(DRCs)is currently the most common treatment for caries.However,existing DRCs suffer from low fracture strength and lack comprehensive anti-caries bioactivity including remineralization,pulp protection,and anti-cariogenic bacteria effects.In this study,inspired by plant roots’ability to stabilize and improve soil,fluorinated urchin-like hydroxyapatite(FUHA)with a three-dimensional whisker structure and bioactive components of calcium,phosphorus,and fluorine was designed and synthesized by a dynamic self-assembly method.Furthermore,versatile FUHA particles with different loading fractions were used as functional fillers to fabricate methacrylate-based DRCs,where the urchin-like hydroxyapatite(UHA)filled DRCs and commercial DRCs(Z350XT and BEAUTIFIL II)served as the control groups.The results demonstrated that FUHA with 50 wt%loading in resin matrix endowed DRC(F5)with excellent physicochemical properties,dentin remineralization property,cell viability,promotion of dental pulp stem cells mineralization,and antibacterial properties.Meanwhile,F5 also presented good clinical handling and aesthetic characteristics.Therefore,structure/functional-integrated FUHA filled DRCs have potential as a promising strategy for tooth restoration and anti-caries bioactivity.

A General Strategy for Efficiently Constructing Multifunctional Cluster Fillers Using a Three-Fluid Nozzle Spray Drying Technique for Dental Restoration

Multifunctional fillers are greatly required for dental resin composites(DRCs).In this work,a spray dryer with a three-fluid nozzle was applied for the first time to construct high-performance complex nanoparticle clusters(CNCs)consisting of different functional nanofillers for dental restoration.The application of a three-fluid nozzle can effectively avoid the aggregation of different nanoparticles with opposite zeta potentials before the spray drying process in order to construct regularly shaped CNCs.For a SiO_(2)–ZrO_(2) binary system,the SiO_(2)–ZrO_(2) CNCs constructed using a three-fluid nozzle maintained their excellent mechanical properties((133.3±4.7)MPa,(8.8±0.5)GPa,(371.1±13.3)MPa,and(64.5±0.7)HV for flexural strength,flexural modulus,compressive strength,and hardness of DRCs,respectively),despite the introduction of ZrO_(2) nanoparticles,whereas their counterparts constructed using a two-fluid nozzle showed significantly decreased mechanical properties.Furthermore,heat treatment of the SiO_(2)-ZrO_(2) CNCs significantly improved the mechanical properties and radiopacity of the DRCs.The DRCs containing over 10%mass fraction ZrO_(2) nanoparticles can meet the requirement for radiopaque fillers.More importantly,this method can be expanded to ternary or quaternary systems.DRCs filled with SiO_(2)-ZrO_(2)-ZnO CNCs with a ratio of 56:10:4 displayed high antibacterial activity(antibacterial ratio>99%)in addition to excellent mechanical properties and radiopacity.Thus,the three-fluid nozzle spray drying technique holds great potential for the efficient construction of multifunctional cluster fillers for DRCs.

Influence of surface roughness on the color of dental-resin composites

This study deals with the influence of surface roughness on the color of resin composites.Ten resin composites (microfilled,hybrid,and microhybrid) were each polished with 500-grit,1 200-grit,2 000-grit,and 4 000-grit SiC papers.The roughness parameter (Ra) was measured using a Plμ confocal microscope,and field-emission scanning electron microscope (Fe-SEM) images were used to investigate filler morphology.Color was measured using a spectroradiometer and a D65 standard illuminant (geometry diffuse/0° specular component excluded (SCE) mode).Surface roughness decreased with grit number and was not influenced by filler size or size distribution.A significant influence of Ra on lightness (L*) was found.Lightness increased with decreases in roughness,except for specimens that underwent polishing procedure 4 (PP4;500-grit,1 200-grit,2 000-grit,and 4 000-grit SiC papers consecutively).Generally,it was found that surface roughness influenced the color of resin composites.The composites that underwent PP1 (500-grit SiC paper) exhibited significant differences in chroma (C*),hue (h°),and lightness (L*) compared to composites that underwent PP3 (500-grit,1 200-grit,and 2 000-grit SiC papers consecutively) and PP4.Color difference (E*) between the polishing procedures was within acceptability thresholds in dentistry.

Mechanical Properties, Biocompatibility and Anti-Bacterial Adhesion Property Evaluation of Silicone-Containing Resin Composite with Different Formulae

Novel branched silicone methacrylate was developed.The mechanical and biological properties of the resin system were investigated to select the formula proportion with the best overall performance.The novel silicone-containing monomers were combined with an incremental sequence of glass filler concentrations in commonly used Bis-GMA/TEGDMA(50/50,wt./wt.)dental resin systems.Physicochemical properties,surface properties,antibacterial adhesion effect,anti-biofilm effect,protein adsorption,and cytotoxicity were evaluated.The results showed that BSMs did not affect the double bond conversion of dental resin,but could reduce volumetric shrinkage(p<0.05).The BSM containing resins can resist protein and bacteria adhesion(S.mutans)because it has increased hydrophobicity and a lower free energy surface(p<0.05).However,there were no statistically significant differences in cytotoxicity,surface roughness,and double bond conversion rate.Overall,the results indicate that changes in a material’s properties are not strictly proportional to its composition.Synthetic silicone resin methacrylate can reduce the polymerization shrinkage,have low surface energy and anti-adhesion properties.Silicone composite resin containing 70%matrix has the best comprehensive properties.The silicone methacrylate composite represents an innovative method to improve the properties and reducing secondary caries.