Niobium silicate particles promote in vitro mineral deposition on dental adhesive resins

Synergistic effect of ion-releasing fillers on the remineralization and mechanical properties of resin-dentin bonding interfaces

In modern restorative dentistry, adhesive resin materials are vital for achieving minimally invasive, esthetic, and tooth-preserving restorations. However, exposed collagen fibers are found in the hybrid layer of the resin-dentin bonding interface due to incomplete resin penetration. As a result, the hybrid layer is susceptible to attack by internal and external factors such as hydrolysis and enzymatic degradation, and the durability of dentin bonding remains limited. Therefore, efforts have been made to improve the stability of the resin-dentin interface and achieve long-term clinical success. New ion-releasing adhesive resin materials are synthesized by introducing remineralizing ions such as calcium and phosphorus, which continuously release mineral ions into the bonding interface in resin-bonded restorations to achieve dentin biomimetic remineralization and improve bond durability. As an adhesive resin material capable of biomimetic mineralization, maintaining excellent bond strength and restoring the mechanical properties of demineralized dentin is the key to its function. This paper reviews whether ion-releasing dental adhesive materials can maintain the mechanical properties of the resin-dentin bonding interface by supplementing the various active ingredients required for dentin remineralization from three aspects: phosphate, silicate, and bioactive glass.

Effects of experimental bleaching gels containing co-doped titanium dioxide and niobium pentoxide combined with violet light

OBJECTIVES

The objective of the study is to evaluate the bleaching potential of 6% hydrogen peroxide (6% HP) gels containing NF_TiO2 or Nb2O5 irradiated with a violet LED light and the effects on enamel mineral content and surface morphology.

METHODS

Particles were synthesized, and experimental gels were chemically analyzed by preliminary and accelerated stability tests, pH, and HP decomposition rate. Bovine enamel blocks were treated with 6% HP gels containing (n = 10): 5% NF_TiO2, 5% Nb2O5, 2.5% NF_TiO2 + 2.5% Nb2O5 or without particles (6% HP), irradiated or not with LED, and the control was treated with 35% HP. Color (∆E00) and whitening index (∆WID) variations, surface microhardness (SH), average roughness (∆Ra), Ca-P concentration (EDS), and enamel morphology (SEM) were assessed. Bleaching was performed in 3 sessions of 30 min and 7-day intervals. Data were submitted to two- (pH, decomposition rate, ∆E00, and ∆WID) or three-way ANOVA and Bonferroni (SH), Kruskal-Wallis (∆Ra), and Dunnet tests (α = 0.05).

RESULTS

No changes in the gel's color, odor, or translucency were observed. The pH (6 to 6.5) remained stable over time, and light irradiation boosted the HP decomposition rate. NF_TiO2 and Nb2O5-containing gels displayed higher ∆E00 and ΔWID when light-irradiated (p < 0.05). Nb2O5 and Nb2O5 + NF_TiO2 decreased enamel SH (p < 0.05), but no SH changes were found among groups (p > 0.05). No differences among groups were noted in ∆Ra, Ca-P content, and enamel morphology after treatments (p > 0.05).

CONCLUSION

Experimental light-irradiated 6% HP gels containing NF_TiO2 or Nb2O5 were chemically stable and exhibited bleaching potential comparable with 35% HP.

CLINICAL RELEVANCE

Low-concentrated HP gels containing NF_TiO2 or Nb2O5 and light-irradiated stand as a possible alternative to in-office bleaching.

Orthodontic resins loaded with niobium silicate particles: Impact of filler concentration on the physicochemical and biological properties

OBJECTIVES

White spot lesions (WSL) are prevalent in patients using orthodontic appliances. The presence of ion-releasing compounds in the tooth-appliance interface may limit enamel demineralization to control WSL incidence. Thus, this study aims to evaluate the mineral formation on SiNb-containing experimental orthodontic resins and the influence of these fillers on the physicochemical and biological properties of developed materials.

MATERIALS AND METHODS

The SiNb particles were synthesized via the sol-gel route and characterized by their molecular structure and morphology. Photopolymerizable orthodontic resins were produced with a 75 wt% Bis-GMA/25 wt% TEGDMA and 10 wt%, 20 wt%, or 30 wt% addition of SiNb. A control group was formulated without SiNb. These resins were tested for their degree of conversion, softening in solvent, cytotoxicity in fibroblasts, flexural strength, shear bond strength (SBS), and mineral deposition.

RESULTS

The addition of 10 wt% of SiNb did not impair the conversion of monomers, cytotoxicity, and flexural strength. All groups with SiNb addition presented similar softening in solvent. The presence of these particles did not affect the bond strength between metallic brackets and enamel, with SBS values ranging from 16.41 to 18.66 MPa. The mineral deposition was observed for all groups.

CONCLUSION

The use of niobium silicate as filler particles in resins may be a strategy for the adhesion of orthodontic appliances. The 10 wt% SiNb concentration resulted in a material with suitable physicochemical and biological properties while maintaining the bond strength to tooth enamel and promoting mineral deposition.

Alkyl trimethyl ammonium bromide for the formulation of antibacterial orthodontic resins

OBJECTIVES

This study aimed at formulating antibacterial orthodontic resins containing alkyl trimethyl ammonium bromide (ATAB) and evaluating their physicochemical and biological properties.

MATERIALS AND METHODS

The chemical composition and microstructure of ATAB was characterized through FTIR and SEM, respectively. Experimental orthodontic BisGMA/TEGDMA-based resins were formulated, and the ATAB filler was incorporated at 1wt%, 5wt%, and 10wt%, along with colloidal silica (5wt%). The degree of conversion, softening in solvent, and flexural strength of the experimental resins were analyzed. Biological properties were also assessed through cytotoxicity and antibacterial analyses.

RESULTS

The incorporation of ATAB, due to the presence of ⎯N⁺(CH₃)₃ alkyl groups, had no adverse effect on the degree of conversion of the resins (p > 0.05). The %ΔKHN values at 5wt% and 10wt% were comparable to those of the control group, while the flexural strength was reduced at all concentrations of ATAB. The viability of the gingival fibroblast was reduced with the addition of ATAB (p < 0.05). The viability of biofilm and planktonic bacteria was reduced when ATAB was incorporated at 5wt% and 10wt%.

CONCLUSIONS

The addition of ATAB at 5wt% resulted suitable for the formulation of orthodontic resins with the ability to control the biofilm formation and planktonic activity of S.mutans, without jeopardizing some specific physicochemical properties.

CLINICAL RELEVANCE

White spot lesions in orthodontic patients may be controlled by preventive treatments. Non-patient-dependent strategies, such as the use of orthodontic resins containing ATAB, may avoid accumulation of bacteria, especially in those areas surrounding orthodontic appliances.

Recent Advances in Direct Adhesive Restoration Resin-Based Dental Materials With Remineralizing Agents

Resin-based dental materials are popular restorative materials especially in direct adhesive restoration because of the excellent mechanical and esthetic properties. Toward the realization of minimally invasive dental procedures, direct composite resin adhesive restoration has become the main treatment for dental defects. In addition, for caries-affected dentin close to the pulp, conservation remineralization has been advocated to save the living pulp. However, the resin–dentin interface can be destabilized by various factors, especially the enzymatic degradation of collagen fibrils within the hybrid layer and polymer hydrolysis. Furthermore, for resin-based restorative materials, the marginal gap remains a major problem that can lead to the occurrence of secondary caries. To address these issues, research efforts have focused on the remineralization of mineral-depleted dental hard tissues using remineralizing bioactive substances. In this review, we first described various bioactive agents with remineralizing properties. Furthermore, we discussed recent advances in resin-based dental materials for enamel or dentin remineralization. Finally, we examined the current challenges and prospects of these emerging materials. This work aims to provide a theoretical foundation for the future development of resin-based dental materials in direct adhesive restoration with remineralizing agents.

Synergistic Effect of Bioactive Inorganic Fillers in Enhancing Properties of Dentin Adhesives-A Review

Dentin adhesives (DAs) play a critical role in the clinical success of dental resin composite (DRC) restorations. A strong bond between the adhesive and dentin improves the longevity of the restoration, but it is strongly dependent on the various properties of DAs. The current review was aimed at summarizing the information present in the literature regarding the improvement of the properties of DAs noticed after the addition of bioactive inorganic fillers. From our search, we were able to find evidence of multiple bioactive inorganic fillers (bioactive glass, hydroxyapatite, amorphous calcium phosphate, graphene oxide, calcium chloride, zinc chloride, silica, and niobium pentoxide) in the literature that have been used to improve the different properties of DAs. These improvements can be seen in the form of improved hardness, higher modulus of elasticity, enhanced bond, flexural, and ultimate tensile strength, improved fracture toughness, reduced nanoleakage, remineralization of the adhesive-dentin interface, improved resin tag formation, greater radiopacity, antibacterial effect, and improved DC (observed for some fillers). Most of the studies dealing with the subject area are in vitro. Future in situ and in vivo studies are recommended to positively attest to the results of laboratory findings.