In vitro effect of calcium nanophosphate and high-concentrated fluoride agents on enamel erosion: an AFM study

Xylitol Fluoride Varnish: In Vitro Effect Analysis on Enamel by Atomic Force Microscopy

(1) Background: Numerous studies have shown the beneficial role of fluoride in the primary prevention of dental caries. The aim of the present study was to put into evidence the change in the enamel structure immediately after the application of a fluoride varnish. (2) Methods: A xylitol−fluoride varnish was evaluated. The enamel specimens (n = 10) were analyzed by atomic force microscopy on enamel surface and treatment with fluoride varnish applied. The dimensional topographic analysis was performed by 2D and 3D analysis software. Statistical analysis was performed using SPSS Version 26.00 (IBM, Armonk, NY, USA). A one-sample statistics test was used to identify significant differences (p < 0.05). (3) Results: Surface roughness (Ra) measurements ranged from Ra = 0.039 μm (±0.048), to Ra = 0.049 μm (±0.031), respectively (p < 0.05), with an increase in the surface roughness passing from the intact enamel to the enamel exposed to fluoride varnish. When comparing Ra values of the nonfluorinated enamel and fluorinated enamel, significant differences (p < 0.05) were found, suggesting that the varnish had a protective effect on the enamel surface. (4) Conclusions: Xylitol−fluoride varnish, even in one single short-time application, is effective in reducing the surface roughness of enamel structure exposed to abrasion, thus increasing resistance to dental caries.

Evaluation of the Efficacy of Different Remineralizing Agents on Artificial Early Enamel Lesions of Primary Teeth: An In Vitro Study

Aim:

To analyze the remineralization efficacy of casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) and 8% arginine on artificial early enamel lesions on primary teeth enamel samples.

Materials and Methods:

In this in vitro study, artificial enamel lesions were created in 120 primary teeth. Teeth were randomly divided into 5 groups: group C: CPP–ACP paste; group CF: CPP–ACPF paste with 900 ppm flour; group A: paste with 8% arginine; group K+: 500 ppm NaF as a positive control; and group K–: deionized water as a negative control. After 4 weeks of the remineralization process, the effect of remineralization on samples of agents used the microhardness, atomic force microscope, and scanning electron microscope analyses. Statistical analysis was done using Statistical Package for the Social Sciences (SPSS version 20.0, SPSS Inc., Chicago, IL, USA). ANOVA and Tukey Post-Hoc multiple comparison test were applied ( p < .05).

Results:

Increasing percentage values of the microhardness at groups C, CF, and A were significantly better than group K– ( p < .05), whereas there is no statistically significant difference with group K+ ( p > .05). The average surface roughness values of groups C and CF were similar with group K+ in AFM analysis, whereas average surface roughness values of group A were significantly higher than K+ group.

Conclusion:

The CPP–ACP, CPP–ACPF, and arginine are effective agents for remineralization of early childhood caries lesions.

Effect of desensitizing agents on the microtensile bond strength of two-step etch-and-rinse adhesives to dentin

Desensitizers can be used to control postoperative sensitivity in adhesive restorations. The aim of this study was to evaluate the effect of desensitizing agents on the bond strength of two-step etch-and-rinse adhesive systems to dentin. Forty-two human molars were sectioned to obtain 3-mm-thick dentin discs. The discs were divided into three groups (n = 14 in each) - no-treatment control group (CT), and oxalic acid [BisBlock (BB)] and calcium phosphate [Desensibilize Nano-P (NP)] desensitizers - before the application of two adhesive systems [Adper Single Bond Plus (SB) and One-Step Plus (OSP)]. A nanoparticle composite resin was used to create a 3-mm-thick build-up. The specimens were stored in distilled water for 24 h before a microtensile bond-strength test was performed. The failure modes were determined using a stereomicroscope at 100 × magnification. Specimens were sectioned perpendicular to the interface for scanning electron microscopy analyses. The CT-SB group exhibited the highest bond strength, differing significantly from BB-SB and BB-OSP groups. Mixed failures were prevalent for all groups. Scanning electron microscopy revealed a continuous hybrid layer and resin tags in all groups. Dentin bond strength of etch-and-rinse adhesive systems was reduced by an oxalic acid desensitizer but was not affected by a calcium phosphate-containing desensitizer.

Effects of erosive challenge on the morphology and surface properties of luting cements

Abstract Introduction Few studies investigated the surface properties of luting cements after erosive challenge. Objective To evaluate the surface roughness (Ra), Vickers hardness (VHN) and morphology of 4 luting cements after erosive challenge. Material and method Twenty specimens of each cement were prepared (4×2mm) and divided into experimental (erosive challenge) and control (artificial saliva) groups (n=10): Rely X U200 (U200); Rely X ARC (ARC); Ketac Cem Easy Mix (Ketac) and Zinc phosphate (ZnP). The erosive challenge was performed by four daily erosive cycles (90s) in a cola drink and 2 h in artificial saliva over 7 days. Ra and VHN readings were performed before and after erosion. The percentage of hardness loss (%VHN) was obtained after erosion. The surface morphology was analyzed by scanning electron microscopy (SEM). ANOVA, Tukey and Student-T tests were used (α=0.05). Result After erosion, all luting cements had increase in Ra values and U200 and ZnP groups had the highest %VHN. After saliva immersion, only U200 and ZnP groups had significant increases in Ra values and there were no significant differences among the groups in %VHN. SEM analysis showed that Ketac and ZnP groups had rough and porous surfaces, and U200 group had higher resin matrix degradation than ARC group. Conclusion Erosive challenge with a cola drink affected the surface properties of all luting cements.