Association of Nd:YAG laser and calcium-phosphate desensitizing pastes on dentin permeability and tubule occlusion

A novel mussel-inspired desensitizer based on radial mesoporous bioactive nanoglass for the treatment of dentin exposure: An in vitro study

OBJECTIVES

The dentin exposure always leads to dentin hypersensitivity and the acid-resistant/abrasion-resistant stability of current therapeutic approaches remain unsatisfatory. Inspired by the excellent self-polymerization/adherence activity of mussels and the superior mineralization ability of bioactive glass, a novel radial mesoporous bioactive nanoglass coated with polydopamine (RMBG@PDA) was developed for prevention and management of dentin hypersensitivity.

METHODS

Radial mesoporous bioactive nanoglass (RMBG) was synthesized by the sol-gel process combined with the cetylpyridine bromide template self-assembly technique. RMBG@PDA was synthesized by a self-polymerization process involving dopamine and RMBG in an alkaline environment. Then, the nanoscale morphology, chemical structure, crystalline phase and Zeta potential of RMBG and RMBG@PDA were characterized. Subsequently, the ion release ability, bioactivity, and cytotoxicity of RMBG and RMBG@PDA in vitro were investigated. Moreover, an in vitro experimental model of dentin hypersensitivity was constructed to evaluate the effectiveness of RMBG@PDA on dentinal tubule occlusion, including resistances against acid and abrasion. Finally, the Young's modulus and nanohardness of acid-etched dentin were also detected after RMBG@PDA treatment.

RESULTS

RMBG@PDA showed a typical nanoscale morphology and noncrystalline structure. The use of RMBG@PDA on the dentin surface could effectively occlude dentinal tubules, reduce dentin permeability and achieve excellent acid- and abrasion-resistant stability. Furthermore, RMBG@PDA with excellent cytocompatibility held the capability to recover the Young's modulus and nanohardness of acid-etched dentin.

CONCLUSION

The application of RMBG@PDA with superior dentin tubule occlusion ability and acid/abrasion-resistant stability can provide a therapeutic strategy for the prevention and the management of dentin hypersensitivity.

Influence of the combined effect of desensitizing dentifrices and universal adhesives on dentin bond strength under erosive conditions

OBJECTIVE

This study aimed to evaluate whether the use of desensitizing dentifrices containing obliterating agents can affect bond strength of eroded/abraded dentin.

METHODOLOGY

A total of 100 dentin samples were obtained from human molars. The teeth were cut into 3 mm-thickness discs and allocated in five groups (n=20), according to the toothpaste used: WoF - abrasion with fluoride-free toothpaste (Cocoricó); Arg - toothpaste containing arginine (Colgate Sensitive Pro-Relief); Nov - calcium sodium phosphosilicate toothpaste (Sensodyne Repair and Protect); SnF - fluoride-containing toothpaste (AmF/SnCl2/SnF2 - Elmex Erosion); and Control (no erosive/abrasive process). The erosive/abrasive cycle consisted of immersion in citric acid (1%, pH 2.6, 5 min, 4×/day) and abrasion (2×/day, 120-20 sec abrasion, 100 sec immersion) with each toothpaste. During intervals, samples were immersed in artificial saliva. This cycle was performed for five days. Two resin cylinders (2 mm in diameter) were constructed on each sample for the shear bond strength test using a universal adhesive system. The self-etch and etch-and-rinse (Scotchbond Universal) strategies were employed, each in half of the total sample (n=10). Bond strength (MPa) was measured in a shear test and failure modes were assessed with a stereomicroscope. Statistical analysis was performed using the two-way analysis of variance (ANOVA) and Tukey tests (p<0.05).

RESULTS

A statistically significant difference was found between the adhesive strategies tested (p<0.001), with the self-etching form showing higher values than the etch-and-rinse. Moreover, no significant differences were observed between the tested toothpastes (p=0.750) and interactions (p=0.438).

CONCLUSION

The use of toothpaste containing obliterating agents does not affect bond strength to dentin subjected to erosive/abrasive conditions when a universal adhesive is used. However, the self-etch strategy might be preferred for eroded/abraded dentin.

Evaluation of the effectiveness of different treatment approaches in preventing coronal discoloration caused by regenerative endodontic treatment

OBJECTIVES

This study aimed to evaluate the effectiveness of Teethmate desensitizer, a dentin bonding agent (DBA), Nd:YAG laser, and Er:YAG laser, which provides dentin tubule occlusion in the pulp chamber with different mechanisms, in preventing tooth discoloration due to regenerative endodontic treatment.

MATERIALS AND METHODS

One hundred five extracted maxillary human incisors with single roots and single canals were included in the study. The apical third of each tooth was resected below the enamel-cementum junction (CEJ) to obtain a standard root length as 10 ± 1 mm. Root canal preparation was performed using the ProTaper Next files up to X5. Root canals were prepared with Gates Glidden (# 2-4) burs to simulate the immature root apex and an apical diameter of 1.1 ± 0.1 mm was obtained. The teeth were randomly divided into 7 groups (n = 15): DBA, Teethmate, Nd:YAG, Er:YAG, Biodentine, Blood, and Negative Control. Relevant dentin tubule occlusion methods were applied to DBA, Teethmate, Nd:YAG, and Er:YAG groups. Following dentin tubule occlusion procedures, Biodentine was placed on the blood clot after filling the root canals with blood up to 4 mm below the CEJ. No dentin tubule occlusion procedure was applied for Blood and Biodentine groups. Color measurement was performed with the spectrophotometer Vita Easyshade Advance before treatment, immediately after treatment, and at days 7, 30, and 90. Data were converted to L*a*b color values of Commission International de I'Eclairage (CIE L*a*b) and ΔE values were calculated. Two-way ANOVA and post hoc Tukey test (p = 0.05) were performed for statistical analysis.

RESULTS

A clinically detectable color change was observed in all groups except for the negative control (ΔE ≥ 3,3). It was observed that Biodentine used alone has a potential for discoloration. It was determined that as the contact time with blood increased, tooth discoloration increased. However, no significant difference was found between dentin tubule occlusion methods in preventing color change (p > 0.05).

CONCLUSIONS

It was determined that no dentin tubule occlusion method could 100% prevent discoloration caused by RET.

CLINICAL RELEVANCE

DBA and Teethmate, which do not have a significant difference in terms of preventing color change, are considered to be suitable for dentin tubule occlusion due to their ease of application and low cost compared to Nd:YAG laser and Er:YAG laser.

Effect of a modified adhesive system with encapsulated arginine and calcium carbonate on dentin permeability

To modify an adhesive system with halloysite clay nanotubes (HNTs) containing arginine and calcium carbonate and to evaluate their cytocompatibility, viscosity and efficacy in reducing dentin permeability. HNTs containing arginine and calcium carbonate were incorporated into the primer and adhesive of a three-step adhesive system (SBMP), and their viscosity was measured. Discs (n = 4/group) were prepared: SBMP (control), HNT-PR (modified primer), HNT-ADH (modified adhesive) and HNT-PR + ADH (modified primer and adhesive) were evaluated regarding cell death and viability. Dentin discs were prepared and randomly assigned into the following treatments (n = 10): NC (no treatment), SBMP, HNT-PR, HNT-ADH, HNT-PR + ADH and COL (Colgate® Sensitive Pro-relief™ prophylaxis paste). After, they were submitted to an erosive-abrasive cycling. Dentin permeability (hydraulic conductance) was evaluated at baseline, 24 h after treatment and after cycling. Both the modified primer and adhesive showed significantly higher viscosity than their controls. Group HNT-PR resulted in significantly higher cytotoxicity when compared to SBMP and HNT-PR + ADH groups. Group HNT-ADH resulted in the highest cell viability compared to all other groups. All groups showed significantly lower dentin permeability when compared to the NC group. Post-cycling, SBMP and HNT-ADH groups showed significantly lower permeability when compared to COL group. The addition of encapsulated arginine and calcium carbonate did not affect the cytocompatibility of the materials nor their ability to reduce dentin permeability.

A 58S bioactive glass for dentin hypersensitivity and erosive tooth wear: An in vitro study

OBJECTIVES

To assess the effect of an experimental 58S bioactive glass on dentin permeability (dP) and erosive tooth wear (dentin surface loss - dSL).

METHODS

58S bioactive glass was synthetized using a sol-gel methodology, following by lyophilization and calcination, then mixed with phosphoric acid to obtain a paste (BGP). Forty-eight dentin disks (1 mm-thick) were used for dP, and 48 dentin slabs (3 mm × 3 mm) for dSL, which were assessed at three time intervals: post-EDTA (5 min in 17% EDTA solution); post-treatment (C: distilled water; BGP: experimental bioactive glass paste; NP: Nupro prophylaxis paste; CXT: Clinpro XT varnish); and post-erosive/abrasive cycling. Data were statistically analyzed (α=0.05).

RESULTS

For dP and dSL, Groups did not differ significantly post-EDTA (p>0.05). Post-treatment, all groups showed lower dP than C (p<0.05), without differing significantly among them. For the dSL analysis, Groups C, BGP and NP did not differ significantly, showing lower values than CXT (p<0.05). Post-cycling, C continued to show the highest dP (p<0.05). Specimens from Group CXT had the lowest dP and did not differ from NP (p=0.86) which did not differ from BGP (p=0.193). For C and BGP, dP value was higher post-cycling than post-treatment (p<0.05). For NP and CXT, these experimental times did not differ (p>0.05). Post-cycling, dSL for C, BGP and NP did not differ significantly; values were higher than those for CXT (p<0.05).

CONCLUSIONS

BGP reduced dP after application, with a reduced effect after cycling. Nonetheless, it was not able to protect dentin against erosive tooth wear.

CLINICAL SIGNIFICANCE

Minimizing dentin hypersensitivity is a challenge in the field of dentistry. The development of alternative products with potential to obliterate dentinal tubules and provide resistance to chemical/mechanical stimuli is, thus, highly desirable. We have proposed a material able to reduce dentin permeability, which has emerged as a promising alternative for this purpose.

S-PRG-based toothpastes compared to NaF toothpaste and NaF varnish on dentin permeability in vitro

Objectives

To analyze the effect of 5 toothpastes containing different percentages of S-PRG fillers compared to NaF toothpaste and NaF varnish on the dentin hydraulic conductance (Lp).

Methodology

Dentin disks (1.0±0.2 mm thickness) were cut from third molars, and their Lp values were evaluated using Flodec. The specimens were allocated into 7 groups (n=8). The minimum (smear layer) and the maximum (after acid etching) Lp values were recorded. Lp was also assessed after treatment with either a 0wt.%, 1wt.%, 5wt.%, 20wt.%, or 30wt.% S-PRG toothpaste, a NaF toothpaste, or a NaF varnish. Toothpastes were applied by brushing for 15 s, allowing it to settle for 1 min, and rinsing with deionized water. The NaF varnish was applied for 4 min and was removed with a probe. Specimens were exposed to citric acid (6%, pH 2.1, 1 min) and their final Lp was recorded. The pH of all products was recorded (n=3) and specimens from each group were analyzed by Laser Scanning Confocal Microscopy (LSCM). Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (a=0.05).

Results

The highest Lp reduction was noticed for the 5wt.% S-PRG toothpaste, NaF toothpaste, and NaF varnish. However, the toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG were similar to all toothpastes but differed from the NaF varnish. After erosion, all groups retrieved their maximum Lp values, except for the NaF varnish. The LSCM evidenced deposits on the surface of specimens treated with 5%, 20%, and 30% S-PRG-based toothpastes and NaF toothpaste. Even more deposits were observed for the NaF varnish. After the erosive challenge, the deposits were diminished in all groups.

Conclusion

Toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG fillers behaved similarly to a conventional NaF toothpaste, even after an erosive challenge. The NaF varnish promoted better reduction of the Lp, but its effect was also diminished after erosion.