Acid Resistance Of Dentin Research Articles

Development of Root Caries Prevention by Nano-Hydroxyapatite Coating and Improvement of Dentin Acid Resistance.

There is no established method for optimizing the use of dentin to prevent root caries, which are increasing in the elderly population. This study aimed to develop a new approach for root caries prevention by focusing on bioapatite (BioHap), a new biomaterial, combined with fluoride. Bovine dentin was used as a sample, and an acid challenge was performed in three groups: no fluoride (control group), acidulated phosphate fluoride treatment (APF group), and BioHap + APF treatment (BioHap group). After applying the new compound, the acid resistance of dentin was compared with that of APF alone. The BioHap group had fewer defects and an increased surface hardness than the APF group. The BioHap group had the smallest lesion depth and least mineral loss among all groups. Using a scanning electron microscope in the BioHap group showed the closure of dentinal tubules and a coating on the surface. The BioHap group maintained a coating and had higher acid resistance than the APF group. The coating prevents acid penetration, and the small particle size of BioHap and its excellent reactivity with fluoride are thought to have contributed to the improvement of acid resistance in dentin. Topical fluoride application using BioHap protects against root caries.

CO<sub>2</sub>レーザー照射が象牙質の耐酸性向上にあたえる影響

CO<sub>2</sub>レーザー照射が象牙質の耐酸性向上にあたえる影響

Acid resistance of dentin after erbium:yttrium-aluminum-garnet laser irradiation

The purpose of this study was to evaluate the acid resistance of erbium:yttrium-aluminum-garnet (Er:YAG) lased sub-surface dentin using a scanning electron microscope (SEM). Dentin disks were exposed to a single pulse of Er:YAG laser irradiation at 80 mJ/pulse under water spray, with the contact sapphire tip vertical to the dentin surfaces (n = 15). Five specimens from the laser-ablated dentin surfaces were observed. Ten specimens were crosscut, exposing the center of the lased point. For five of the specimens, the sub-surface of the lased dentin, with or without 10% phosphoric acid treatment, was evaluated. We used the remaining five specimens to analyze the degree of acid treatment on crosscut surface by observing the re-crosscut surfaces at the lased point. The irradiated dentin surfaces were irregular, scaly or flaky. Three sub-layers were observed in the sub-surface: a superficial, less decalcified layer; an intermediate most decalcified layer; and a deep, normal shade layer. Er:YAG laser irradiation affected the acid resistance of sub-surface dentin.

The effect of pulsed Nd–YAG laser irradiation on acid resistance of dentin

The purpose of this study was to examine the effect of tip–object distance in Nd–YAG laser irradiation on the acid resistance and morphological change of dentin. Freshly extracted human premolars were used. Each crown was cut in half transversally. Samples were randomly assigned to five groups as follows. Group 1: noncontact laser irradiated with 100 mJ, 10 pps (tip–object distance was approximately 2 mm). Group 2: contact laser irradiated with 100 mJ, 10 pps. Group 3: noncontact laser irradiated with 200 mJ, 10 pps. Group 4: contact laser irradiated with 200 mJ, 10 pps. Group 5: control. For acid resistance testing, they were individually immersed in acetic buffer solution (0.2 M, pH 4.2). The amount of dissolved Ca 2+ in each solution was determined by sequential plasma spectrometry. The laser-irradiated dentin surface had morphological characteristics such as a cracker or lava. The dissolved Ca 2+ from lased dentin was significantly less than that of the control group. In the group of noncontact lased dentin, the dissolved Ca 2+ lased with 100 mJ is less than that of lased with 200 mJ. In the contact lased group, the dissolved Ca 2+ lased with 200 mJ is less than that lased with 100 mJ. These results lead the optimum pulsed Nd–YAG laser-irradiated condition of different tip–object distance on acid resistance of dentin.

In vitro dentine fluoride uptake from three fluoride-containing composites and their acid resistance

Objectives: The purpose of this study was to determine the dentine fluoride uptake from three fluoride-containing composites (FluorEver, FluoroCore and Pertac-Hybrid) and to investigate their ability to affect the resistance of dentine to an artificial caries challenge. Methods: Three dentine slabs were prepared from each tooth. The baseline, total and bound fluoride concentrations of each tooth were determined by three successive abrasion biopsies performed on each slab followed by adjusting to standardized depths of 10 μm. Next, dentine slabs ligated with the composites were suspended in synthetic saliva for 1 week. After removal of the composites, these specimens and controls were immersed in an artificial caries medium (pH 4.5) for 5 days. Each slab was sectioned and analysed by quantitative microradiography. Results: The results indicate that dentine acquired significantly different amounts of fluoride from the three composites. The acid resistance of dentine in contact with the composites was also significantly different among the composites and followed the same order as for fluoride uptake. Conclusions: Dentine fluoride uptake and artificial caries inhibition were significantly greater with FluorEver followed by FluoroCore and Pertac-Hybrid.