Influence of dentin pretreatment with 2.5% titanium tetrafluoride on inhibiting caries at the tooth-restoration interface in situ

Bonding durability and remineralizing efficiency of orthodontic adhesive containing titanium tetrafluoride: an invitro study

BACKGROUND

Titanium tetrafluoride has been shown to protect tooth enamel from demineralization. This study investigated the effect of incorporating different concentrations of TiF4 (1, 2 and 3 Wt.%) into an orthodontic primer on the shear bond strength of orthodontic brackets and the enamel microhardness after cariogenic challenges.

METHODS

Three different TiF4 concentrations (1, 2 and 3 Wt.%) were prepared and added to the etch and rinse orthodontic primer. Ninety freshly extracted premolars were randomly divided into five groups according to the experimental primers and ageing conditions: TF0, TF0C, TF1C, TF2C, and TF3C. The TF0C group had no TiF4 in the primer, while TF1C, TF2C, and TF3C had 1, 2 and 3 Wt.% TiF4 in the primer, respectively. In the TF0 group, specimens were immersed in deionized water for 24 h as a control group, while all other groups were immersed in a demineralizing solution for 28 days. Each of the five groups was divided into two subgroups: The first group was subjected to shear bond strength and adhesive remnant index testing (N = 50 teeth, 10/group), while the second group was subjected to enamel surface microhardness testing (N = 25 teeth, 50 tooth halves, 10 tooth halves/group). Fifteen teeth (N = 15 teeth, n = 3/group) representing the five groups were subjected to SEM and microelemental analysis (EDX). SBS, ARI, microhardness, and Ca/P ratio were measured, and the data were analyzed using ANOVA and Tukey's tests.

RESULTS

The TF2C group had the highest SBS value (9.93 ± 1.23), while the TF0C (5.24 ± 0.65) and TF3C (5.13 ± 0.55) had the lowest SBS values. The enamel microhardness in the TF0C group was significantly reduced (p < .001). Enamel microhardness values were significantly (p < .001) higher in groups TF1C, TF2C, and TF3C than in TF0C. The highest Ca/P ratio was significantly recorded for the TF2C group (2.65 ± 0.02).

CONCLUSIONS

Incorporation of 1 and 2 Wt.% TiF4 into the orthodontic primers showed adequate bond strength and better remineralization effect. However, 1 Wt.% TiF4 showed lower ARI values than 2 Wt.% TiF4.

An In-Vitro Comparative Evaluation of Pre-treatment With Nano-Silver Fluoride on Inhibiting Secondary Caries at Tooth Restoration Interface

Introduction and aim

Dental caries is the global burden worldwide and has a negative effect on the quality of life. Restorative materials in pediatric dentistry have shown satisfactory properties; however, the highest failures are still reported due to the occurrence of secondary caries. The article aims to assess the effectiveness of pre-treatment with nano-silver fluoride (NSF) in inhibiting secondary caries at the tooth restoration interface.

Materials and methods

Forty tooth specimens were prepared from 20 newly extracted human premolar teeth by sectioning the tooth mesiodistally. Class V cavities were prepared on each specimen at enamel dentin junction. Specimens were randomly distributed into four groups (n=10): 1) glass ionomer cement (GIC) restoration, 2) composite restoration 3) NSF pre-treatment + GIC restoration, 4) NSF pre-treatment + composite restoration. After sterilization, specimens were subjected to artificial caries formation by pH cycling method for 14 days. Specimens were sectioned and mounted to evaluate the demineralization by using the Vickers microhardness test. Outer lesion depth was measured at the tooth restoration interface on digital radiographs. Data was analyzed using Student unpaired t-test, one-way ANOVA, and Tukey honestly significant difference (HSD) post hoc test.

Results

The mean microhardness value of pre-treated GIC and composite group with NSF was more than the non-treated NSF group, with a significant difference at the enamel, indicating lesser demineralization. Outer lesion depth was lesser in the pre-treated group showing better tooth restoration integrity with a statistically significant difference between the groups.

Conclusion

Pre-treatment with NSF is beneficial in increasing the resistance of GIC and composite resin restoration to secondary caries formation.

Effects of S. mutans gene-modification and antibacterial calcium phosphate nanocomposite on secondary caries and marginal enamel hardness

Secondary caries at the restoration-tooth margins is a main reason for dental restoration failures. Gene-modification for Streptococcus mutans (S. mutans) and composites containing dimethylaminohexadecyl methacrylate (DMAHDMA) and nanoparticles of amorphous calcium phosphate (NACP) all have the potential to suppress bacterial acids and promote remineralization. However, there has been no report of their effects on marginal caries-inhibition and enamel hardness. The objective of this study was to investigate the effects of gene-modification and DMAHDM-NACP composite restoration on enamel demineralization and hardness at the margins under biofilm acids for the first time. Parent S. mutans and rnc gene-deleted S. mutans were tested side by side. The bioactive composite contained 3% DMAHDM and 30% NACP. Mechanical properties and calcium (Ca) and phosphate (P) ion releases were measured. Colony-forming units (CFU), MTT, lactic acid and polysaccharide of biofilms were evaluated. Demineralization of bovine enamel with composite restorations was induced via biofilms, then enamel hardness was measured. The dual strategy of combining rnc-deletion with DMAHDM+30NACP: (1) achieved the strongest biofilm-inhibition, with the greatest reduction in biofilm CFU by 6 logs; (2) decreased biofilm lactic acid and polysaccharide production by more than 80%; (3) achieved enamel hardness that was 140% higher than that of a commercial fluoride-releasing composite under 30 days of biofilm acids. Therefore, the novel dual approach of rnc gene-deletion and DMAHDM+NACP nanocomposite is promising to inhibit secondary caries at the margins and increase the longevity of tooth restorations.