Prevention of Root Caries Using Oxalic Acid.

Certain dentin hypersensitivity treatment materials include oxalic acid to coat dentin surfaces with minerals, while certain organic acids possess a remineralization effect. Herein, an organic acid that inhibits the demineralization and coating of root surfaces was evaluated. Specimens were produced using five non-carious extracted bovines. Four different acids were used: oxalic acid (OA), malonic acid (MA), polyacrylic acid (PA), and succinic acid (SA). Each acid was applied to the root surface and washed using distilled water or a remineralization solution, and the surface was observed using scanning electron microscopy (SEM). All the surfaces of each specimen, barring the polished surface, were covered with wax and immersed in an automatic pH cycling system for two weeks. Dentin demineralization was analyzed using transverse microradiography (TMR) before and after pH cycling. SEM analysis demonstrated that the three acid groups demineralized the dentin surface, whereas the OA group generated crystals covering the dentin surface, even in a distilled water environment. TMR analysis revealed that the OA groups showed significantly lower integrated mineral loss compared with the other groups, even in the distilled water environment. The results suggest that OA generates insoluble calcium oxalate crystals on the dentin and suppresses demineralization even under low saliva conditions.

Potential of Fluoride-Containing Zinc Oxide and Copper Oxide Nanocomposites on Dentin Bonding Ability.

Despite recent advances in bonding restorations, which are the basis of restorative dentistry, secondary caries are still able to form. Previously, a novel fluoride-containing zinc and copper (ZCF) nanocomposite was introduced to prevent the formation of caries due to its antibacterial activity. In this study, we studied the impact of ZCF nanoparticles on the adhesive strength of bonding restorations through micro-tensile bond strength (µTBS) testing. The impact of antibacterial and matrix metalloproteinase (MMP) inhibitors on the nanoparticles was also examined. The nanocomposites were prepared using a simple one-step homogeneous co-precipitation method at a low temperature. A self-etch adhesive was applied to 10 extracted caries-free human molars with (test group) and without (control group) the ZCF nanoparticles. This was followed by composite resin build-up and µTBS testing, MMP activity assays, and evaluation of the antibacterial effects. The results showed no significant differences in the µTBS between the ZCF and the control groups. However, the ZCF exhibited a significant inhibitory effect against MMP-2, MMP-8, and MMP-9, in addition to an antibacterial effect on Streptococcus mutans. Therefore, the present study demonstrated that the addition of ZCF nanoparticles to adhesive systems can result in MMP inhibition and antibacterial action while maintaining the mechanical properties of the bonding restorations.

Distribution of elements in teeth and inhibition of demineralization by titanium fluoride: Effects of concentration and pH in a titanium fluoride solution.

The purpose of this study was to assess the effects of titanium fluoride (TiF4) concentration and pH on fluoride distribution and demineralization of root dentin surfaces. Concentrations of 0.1%, 1%, and 2% TiF4 (pH 1), 1% TiF4 solution adjusted to pH 4, 5, 6, and 1.35% sodium fluoride (NaF) solution were applied to root dentin surfaces. Each specimen was subjected to pH cycling (pH: 4.5-7.0) for 4 weeks. Lesion depth and calcium, fluorine, and titanium distribution were then evaluated. Our limited study indicates that lesion depth and fluorine and titanium distribution in dentin depend on the concentration of a TiF4 solution. We also found that a 1% TiF4 solution adjusted to a pH 4-6 can reduce demineralization as effectively as a similar concentration of NaF.

[Case of recurrent fungal endophthalmitis with suspected Munchausen syndrome].

PURPOSE: To report recurrent fungal endophthalmitis which developed after endogenous fungal endophthalmitis. The patient was suspected to be suffering from Munchausen syndrome. CASE: A 44-year-old woman contracted endogenous fungal endophthalmitis in her right eye in October 2000. After the endophthalmitis was healed by vitrectomy, corneal ulcer and endophthalmitis repeatedly occurred in the eye from an unknown cause. The patient finally lost the sight of her right eye. The corneal ulcer and endophthalmitis resulted from self-injury for which we found material evidence in the course of the treatment. Munchausen's syndrome was suspected but the patient persistently refused to see a psychiatrist. CONCLUSION: We must be prepared to provide mental and psychiatric care in addition to ophthalmological treatment for such a case.