The impact of glass ionomer cement and composite resin on microscale pH in cariogenic biofilms and demineralization of dental tissues

Novel antibacterial orthodontic elastomeric ligature with oral biofilm-regulatory ability to prevent enamel demineralization

OBJECTIVES

To synthesize a novel antibacterial orthodontic elastomeric ligature incorporating dimethylaminohexadecyl methacrylate (DMAHDM) for the first time to prevent enamel demineralization during orthodontic therapy.

METHODS

Various mass fractions of DMAHDM (ranging from 0 % to 20 %) were grafted onto commercial elastomeric ligatures using an ultraviolet photochemical grafting method and were characterized. The optimal DMAHDM concentration was determined based on biocompatibility and mechanical properties, and the antibacterial efficacy was evaluated in a whole-plaque biofilm model. TaqMan real-time polymerase chain reaction and fluorescence in situ hybridization were used to assess the microbial regulatory ability of the multispecies biofilms. Furthermore, an in vitro tooth demineralization model was established to explore its preventive effects on enamel demineralization. Statistical analysis involved a one-way analysis of variance and LSD post hoc tests at a significance level of 0.05.

RESULTS

The elastomeric ligature containing 2 % mass fraction of DMAHDM exhibited excellent mechanical properties, favorable biocompatibility, and the most effective antibacterial ability against microorganisms, which decreased by almost two logarithms (P < 0.05). It significantly reduced the proportion of Streptococcus mutans in the multispecies plaque biofilm by 25 % at 72 h, leading to an enhanced biofilm microenvironment. Moreover, the novel elastomeric ligature demonstrated an obvious preventive effect on enamel demineralization, with an elastic modulus 30 % higher and hardness 62 % higher than those of the control group within 3 months (P < 0.05).

SIGNIFICANCE

The integration of DMAHDM with an elastomeric ligature holds significant promise for regulating biofilms and preventing enamel demineralization in orthodontic applications.

Effect of Zeolite Incorporation on the Ion Release Properties of Silver-Reinforced Glass Ionomer Cement

BACKGROUND

Zeolite can release antimicrobial silver ions in a targeted and controlled manner for an extended time, selectively inhibiting the growth of pathogenic oral bacteria when added to dental materials. The objective of this study was to investigate the effect of the addition of zeolite to silver-reinforced glass ionomer cement on the release of silver ions over time.

METHODS

Five concentrations of silver-zeolite (0%, 0.5%, 1%, 2%, 4% wt) were incorporated into silver-reinforced GIC in the form of 10 mm × 2 mm circular disks (n = 5). The disks were incubated in deionized water at 37 °C and ion release from the samples was measured at 1, 2, 7, and 30 days after immersion by inductively coupled atomic emission spectroscopy.

RESULTS

Incorporating silver-zeolite increased silver ion release from silver-reinforced GIC disks compared to the control disks (p < 0.05), while incorporating zeolite alone had no effect. Higher concentrations of added silver-zeolite resulted in increased silver ion release. Sustained silver ion release was observed for up to 30 days.

CONCLUSION

Adding silver-zeolite to silver-reinforced GIC may enhance its extended antibacterial effect in the oral cavity.

In vitro remineralization by various ion-releasing materials of artificially demineralized dentin: A micro-CT study

OBJECTIVE

The aim of this study was to evaluate the remineralizing properties of ion-releasing restorative materials on pH cycling-induced carious dentin.

METHODS

Fifty sound molars were freshly extracted. The occlusal surfaces were abraded using water-cooled sandpaper (800 grit). The residual crowns were embedded in self-cured acrylic resin with the flat dentin surface exposed. A mesio-distal trench was created using a calibrated 0.5 mm deep occlusal reduction burr, and artificial dentin caries were generated by pH cycling. Then, teeth were randomly assigned to five groups according to the ion-releasing material used. For each sample, micro-CT acquisitions were performed at various intervals. Remineralization was assessed by mean gray value (MGV) measurements after registration and segmentation of the region of interest with 3D Slicer software. One-way repeated-measures ANOVA followed by Tukey's post hoc test was used to investigate the difference in MGVs among the various groups.

RESULTS

Only Cention Forte showed significantly increased MGVs after 4 weeks compared to demineralized dentin. MGVs were higher, but not significantly, after placement of the restorative materials, including in the resin composite control group. These results can be explained by the radiopacity of the materials.

SIGNIFICANCE

Cention Forte, the material with the highest radiopacity, showed a significant increase in the MGVs of artificially carious dentin after 4 weeks. However, the study of dentin remineralization by micro-CT could be impacted by the radiopacity of the restorative materials used. The relevance of this examination for the study of dentinal remineralization should be investigated.

Evaluation of Antibacterial Activity of a Bioactive Restorative Material Versus a Glass-Ionomer Cement on Streptococcus Mutans: In-Vitro Study

BACKGROUND

Dental caries management consists of both preventive and restorative approaches. Pediatric dentists can rely on many techniques and materials to restore decayed teeth, but a high failure rate is still observed, mainly due to secondary caries. New restorative bioactive materials combine the mechanical and aesthetic characteristics of resinous materials with the capability to remineralize and the antimicrobial properties of glass ionomers, thus counteracting the occurrence of secondary caries. The aim of this study was to assess the antimicrobial activity against Streptococcus mutans of a bioactive restorative material (ACTIVA™ BioActive-Restorative™-Pulpdent©) and a glass ionomer cement with silver particles added (Ketac™ Silver-3M©), using agar diffusion assay.

METHODS

Each material was formed into disks of 4 mm in diameter, and four discs of each material were placed on nine agar plates. The analysis was repeated seven times.

RESULTS

Both materials showed statistically significant growth inhibition properties against S. mutans (p < 0.05). The difference in the effectiveness of the two materials was not statistically significant.

CONCLUSION

Both ACTIVA™ and Ketac™ Silver can be recommended since both are similarly effective against S. mutans. However ACTIVA™, given its bioactivity and better aesthetics and mechanical properties compared to GICs, may provide better clinical performance.

The preventive effect of glass ionomer restorations on new caries formation: A systematic review and meta-analysis

OBJECTIVE

To investigate the effectiveness of glass ionomer cement (GIC) restorations on preventing new caries in primary or permanent dentitions compared with other types of restorations.

DATA

Randomized controlled clinical trials evaluating caries experience increment or caries incidence in patients with GIC restorations, including conventional GIC (CGIC) and resin-modified GIC (RMGIC) restorations, were included.

SOURCES

A systematic search of publications in English was conducted in PubMed/Medline, Web of Science, Cochrane, and Scopus databases.

STUDY SELECTION/RESULTS

This review included 10 studies reporting caries preventive effect of GIC restorations and selected 5 studies for meta-analysis. Patients with GIC restorations showed lower caries incidence compared with other restorations in primary and permanent dentition [RR=0.67, 95% CI:0.55-0.82, p<0.0001]. Patients with CGIC restorations showed lower caries incidence compared with amalgam restorations [RR=0.57, 95% CI:0.43-0.76, p=0.0001] and RMGIC restorations [RR=0.70, 95% CI:0.56-0.87, p=0.002], but no statistical difference with composite resin restorations [RR=0.73, 95% CI:0.51-1.04, p=0.08] in primary dentition. Patients with RMGIC restorations showed no statistical differences of caries incidence compared with composite resin restorations in primary and permanent dentition [RR=0.83, 95% CI:0.56-1.22, p=0.33].

CONCLUSIONS

GIC restorations presented a better preventive effect on new caries than other restorations did in primary and permanent dentitions. CGIC restorations presented a better caries preventive effect on new caries than RMGIC and amalgam restorations in primary dentitions did. RMGIC restorations showed similar preventing effect on new caries with composite resin restorations in primary and permanent dentitions.

CLINICAL SIGNIFICANCE

This review affirmed the potential of GIC in preventing new caries development in the dentition.

The reciprocal interaction between fluoride release of glass ionomers and acid production of Streptococcus mutans biofilm

Objectives

The aim of this study was to demonstrate the mode of action of glass ionomers (G-Is) against cariogenic biofilms in the slow fluoride release phase by analyzing the reciprocal interaction between fluoride release from G-Is and acid production of Streptococcus mutans biofilm.

Methods

G-Is discs in the slow fluoride release phase were prepared and 51 h-old S. mutans biofilms were formed on these discs. The interrelationship between the acid production of the biofilm and the fluoride release of the G-Is discs was investigated by analyzing both factors simultaneously during the biofilm formation period. The composition of the 51 h-old biofilms was then examined using microbiological, biochemical, and confocal laser scanning microscopic methods.

Results

Acid production by the cariogenic biofilm, particularly at < pH 5, promotes G-Is fluoride release. Conversely, G-Is fluoride release inhibits the acid production of the cariogenic biofilm. This reciprocal interaction results in the reduction of virulence such as extracellular polysaccharides formation and cariogenic biofilm bio-mass, which may reduce the potential of secondary caries development around G-Is.

Conclusions

These results suggest that G-Is may play a role in preventing the development of secondary caries during the slow fluoride release phase.