Daisuke Inaba

Relationship between Electrical Resistance Measurements and Microradiographic Variables during Remineralization of Softened Enamel Lesions

The purpose of this study was to investigate the relationship between electrical resistance (ECM) measurements and microradiographic variables during remineralization of softened enamel lesions. Sound bovine enamel blocks were demineralized and, subsequently, were remineralized for 3, 4, 5, 7 or 14 days. All the specimens were assessed by ECM and transversal microradiography. The mean ECM values in each group increased after remineralization. The ECM values after remineralization (ECM1), mineral loss (ΔZ) and maximum mineral content in the surface layer (Vmax) were significantly correlated with the remineralization time. The ECM1 values were also significantly correlated with ΔZ and Vmax. It is suggested that ECM could be used as a device to monitor mineral accumulation as a result of preventive treatment in vitro. However, it may take a much longer time to follow up the remineralization changes compared with demineralization.

Validity of Screening Methods for Periodontitis Using Salivary Hemoglobin Level and Self-Report Questionnaires in People with Disabilities

BACKGROUND The aim of this study is to evaluate the validity of screening methods in predicting periodontitis in people with disabilities using the objective salivary hemoglobin level, a subjective self-report questionnaire, and a combined model of the two methods with demographic characteristics. METHODS The participants were 195 patients with disabilities aged >18 years who were examined using the community periodontal index (CPI), salivary hemoglobin level, and answers to 10 self-report questions (n = 192). Multivariable logistic regression and receiver operating characteristic (ROC) curve analysis were performed to evaluate the validity of the methods and the combined model in predicting the prevalence of ≥CPI 3 (probing depth [PD] ≥4 mm) or CPI 4 (PD ≥6 mm). RESULTS Overall, 75.9% of the study group (148 of 195) were diagnosed with ≥CPI 3, and 38.5% of the study group (75 of 195) were diagnosed with CPI 4. The areas under the ROC curve (AUCs) of the salivary hemoglobin level were 0.578 (sensitivity of 41% and specificity of 77%) and 0.662 (sensitivity of 53% and specificity of 75%) for predicting the prevalence of ≥CPI 3 and CPI 4, respectively. Multivariable modeling incorporating four different questions for predicting ≥CPI 3 or CPI 4 indicated higher AUCs of 0.710 and 0.732, respectively, yielding higher sensitivity (55% for ≥CPI 3 and 69% for CPI 4) than that of salivary hemoglobin level. The most useful prediction models for ≥CPI 3 or CPI 4 were combined models, which yielded AUCs of 0.773 and 0.807, respectively, with sensitivity values of 70% and specificity values >75%. CONCLUSION The salivary hemoglobin level, self-report questionnaire, and the combined method demonstrated screening potential that could predict the population prevalence of ≥CPI 3 or CPI 4.

Evaluation of penetration effect of resin infiltrant using optical coherence tomography

OBJECTIVE The aims of this in vitro study were to investigate whether optical coherence tomography (OCT) could analyze infiltration of resin infiltrant (RI) into early dental caries (EC), and to confirm the correlation between the results of OCT and confocal laser scanning microscopy (CLSM) for evaluation of RI infiltration into EC. METHODS Sound bovine permanent teeth were used to produce sixty specimens by making two windows on the teeth. Each 20 specimens were demineralized for 20, 30, and 40 days, and the RI was treated on one of the windows. As a result, the images of the fifty-two specimens were taken by OCT and CLSM. The demineralized lesion depth (LDOCT and LDCLSM) and the infiltrated depth of RI into lesion (IDOCT and IDCLSM) obtained from the OCT and the CLSM were analyzed. The correlations between the LDOCT and the LDCLSM, and between the IDOCT and the IDCLSM, were analyzed by Pearson correlation and intra-class correlation. Also, Bland-Altman plot was constructed to assess the agreement between the IDOCT and the IDCLSM, and the IDOCT divided by refractive index of RI and the IDCLSM. RESULTS The Pearson correlation coefficient and intra-class correlation of 0.75 and 0.83 (95% CI: 0.71-0.91) respectively were confirmed between the LDOCT and the LDCLSM (p<0.001), and 0.59 and 0.71 (95% CI: 0.50-0.84) respectively were observed between the IDOCT and the IDCLSM (p<0.001). The lower bias was confirmed in Bland-Altman plot between adjusted IDOCT and the IDCLSM than between the IDOCT and the IDCLSM. CONCLUSION The OCT was the promising quantitative evaluation method for RI penetrated into EC. CLINICAL SIGNIFICANCE The OCT would be used as a nondestructive and real-time evaluation method for RI penetrated into EC on clinical procedure.

Evaluation of resin infiltration using quantitative light-induced fluorescence technology

OBJECTIVES To determine whether quantitative light-induced fluorescence (QLF) technology can be used to classify the colour of teeth specimens before and after resin infiltration (RI) treatment, and calculate the correlation between the ΔF value and colour difference (ΔE) in fluorescence images of the specimens obtained using a QLF-digital (QLF-D) device. METHODS Sixty sound bovine permanent teeth specimens were immersed in demineralized solution. Two exposed windows were formed in each specimen, and RI treatment was applied to one of them. The ΔE values were obtained for the differences between a sound tooth surface (SS), an early dental caries surface (ECS) and an ECS treated with RI (RS) in white-light and fluorescence images obtained using QLF-D, respectively. The ΔF value was obtained from fluorescence images using dedicated software for QLF-D. The mean differences between the ΔE values obtained from the white-light and fluorescence images were analyzed by paired t-test. Pearson correlation analysis and Bland-Altman plots were applied to the differences between the ΔF value for ECS (ΔFSS-ECS) and the ΔE value between SS and ECS (ΔESS-ECS), and between the ΔF value for RS (ΔFSS-RS) and the ΔE value between SS and RS (ΔESS-RS) in fluorescence images. RESULTS The ΔE values obtained from fluorescence images were three times higher than the ΔE values obtained from white-light images (p<0.001). Significant correlations were confirmed between ΔESS-ECS and ΔFSS-ECS (r=-0.492, p<0.001) and between ΔESS-RS and ΔFSS-RS (r=-0.661, p<0.001). CONCLUSION QLF technology can be used to confirm the presence of RI in teeth.

The Effects of Q-switched Nd: YAG Laser Irradiation on Demineralization in Early Enamel Caries Lesions

本研究はレーザー照射の脱灰エナメル質におよぼす影響をin vitroとin situで検討する目的で実施した。人工的に脱灰したエナメル質にQ-switched Nd: YAG第2高調波 (532nm; 100J/cm2) を照射した。続いて, 非照射の対照を含む試料を, pH5の酸性ゲルに3週間浸漬, または上顎第一大臼歯の頬側面に接着して16名の成人口腔内に1か月間接触させた。エナメル質表層のミネラル分布はマイクロラジオグラフィ (TMR) と画像定量法により評価した。paired t-testの結果, いずれの実験においてもミネラルパラメータ値はレーザー照射と非照射試料の間においてP=0.05で有意な違いを示さなかった。結論として, 今回の結果はエナメル質病巣のさらなる脱灰進行が使用したレーザーによっては効果的に抑制されないことを示唆した。