Effect of Mechanical Load Cycling on Microleakage of Restorative Glass Ionomers Compared to Flowable Composite Resin in Class V Cavities

The effect of dental material type and masticatory forces on periodontitis-derived subgingival microbiomes

Restorative dental materials can frequently extend below the gingival margin, serving as a potential haven for microbial colonization, and altering the local oral microbiome to ignite infection. However, the contribution of dental materials on driving changes of the composition of the subgingival microbiome is under-investigated. This study evaluated the microbiome-modulating properties of three biomaterials, namely resin dental composites (COM), antimicrobial piezoelectric composites (BTO), and hydroxyapatite (HA), using an optimized in vitro subgingival microbiome model derived from patients with periodontal disease. Dental materials were subjected to static or cyclic loading (mastication forces) during biofilm growth. Microbiome composition was assessed by 16S rRNA gene sequencing. Dysbiosis was measured in terms of subgingival microbial dysbiosis index (SMDI). Biomaterials subjected to cyclic masticatory loads were associated with enhanced biofilm viability except on the antibacterial composite. Biomaterials held static were associated with increased biofilm biomass, especially on HA surfaces. Overall, the microbiome richness (Chao index) was similar for all the biomaterials and loading conditions. However, the microbiome diversity (Shannon index) for the HA beams was significantly different than both composites. In addition, beta diversity analysis revealed significant differences between composites and HA biomaterials, and between both loading conditions (static and cyclic). Under static conditions, microbiomes formed over HA surfaces resulted in increased dysbiosis compared to composites through the enrichment of periopathogens, including Porphyromonas gingivalis, Porphyromonas endodontalis, and Fretibacterium spp., and depletion of commensals such as Granulicatella and Streptococcus spp. Interestingly, cyclic loading reversed the dysbiosis of microbiomes formed over HA (depletion of periopathogenes) but increased the dysbiosis of microbiomes formed over composites (enrichment of Porphyromonas gingivalis and Fusobacterim nucleatum). Comparison of species formed on both composites (control and antibacterial) showed some differences. Commercial composites enriched Selenomonas spp. and depleted Campylobacter concisus. Piezoelectric composites effectively controlled the microbiome viability without significantly impacting the species abundance. Findings of this work open new understandings of the effects of different biomaterials on the modulation of oral biofilms and the relationship with oral subgingival infections.

Comparative Evaluation of Marginal Integrity of Three Esthetic Restorative Materials - An In-vitro Study

Context

Microleakage is the major cause for the failure of dental restorations, especially in Class V cavities, as margins of such restorations are generally located in dentin or cementum. Microleakage evaluation is necessary as a means of evaluation of the marginal integrity of restorative materials. This would assist in developing techniques and materials that would reduce damage caused by the failure of the restorative marginal seal.

Aim

The aim of this study is to analyze and compare the marginal integrity among three esthetic restorative materials, namely GC Fuji II LC, GC G-Aenial anterior composite resin, and GC Equia forte fil.

Setting and Design

Sixty orthodontically extracted caries-free premolar teeth with Class V restorations were divided into three groups. Microleakage was measured using an ordinal scale of 0-4, as given by Khera and Chan, in increasing order of dye penetration, which was observed under a microscope.

Materials and Methods

Study was conducted in sound human extracted premolars in which Standardized Class V cavities were prepared. Teeth were randomly and equally assigned to three groups (GC Fuji II LC, GC G-Aenial anterior composite resin, and GC Equia forte fil). Teeth were sectioned longitudinally into two halves using diamond discs and the sectioned halves of the teeth were evaluated for dye penetration under stereomicroscope.

Statistical Analysis Used

Intergroup comparison of mean dye penetration scores were compared using the Kruskal-Wallis test along with post hoc pairwise comparison by Mann Whitney U test. The level of statistical significance was set at 0.05.

Results and Conclusion

All the three groups (GC Fuji II LC, GC G-Aenial anterior composite resin, and GC Equia forte fil) tested showed microleakage at the tooth restoration interface. It was evident that microleakage was found to be highest with the Fuji II LC, both at occlusal and cervical levels. GC Equia forte exhibited the best performance in limiting microleakage around the restoration margins.