We evaluated the effect of dentifrice containing 3% vitamin C on periodontitis. Institutional ethics committee approval was obtained prior to the study. Sixty patients (26 men and 34 women) with periodontitis were enrolled in this double-blind clinical trial. We prepared three types of dentifrice: one containing 5.0% zeolite, 0.68% sodium monofluorophosphate, 0.05% cetylpyridinium chloride and 0.05% β-glycyrrhetinic acid (D-1); one with 1.0% vitamin C added to D-1 (D-2); and one with 3.0% vitamin C added to D-1 (D-3). Dentifrice was randomly assigned among subjects, each of whom was required to brush twice daily for 4 weeks. Periodontal indices were measured at baseline and at 2- and 4-week evaluations. The results for mean gingival index (GI), probing depth (PD) and bleeding scores in all groups revealed statistically significant differences between at baseline and at the 2-week evaluation (p<0.01) and between at baseline and at the 4-week evaluation (p<0.01). The results for mean GI, PD and bleeding scores with D-2 and D-3 revealed statistically significant differences between D-1 and D-2 and between D-1 and D-3 at the 2- and 4-week evaluations (p<0.01). Of the three dentifrices, D-3 was the most effective. Statistically significant differences in mean GI (p<0.05) and PD (p<0.05) were observed between D-2 and D-3. These results suggest that a dentifrice containing 3% vitamin C is more effective against periodontitis than one containing 1% vitamin C.

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A caries detector dye, 1% acid red in propylene glycol, has been generally used for minimal removal of carious lesions. However, the evaluations of the degree of staining are subjective. Therefore, a new caries detector dye, 1% acid red in polypropylene glycol, Caries Check® (Nippon Shika Yakuhin) was developed for minimal and objective removal of carious lesions. In this study, the objectivity of removal of caries was evaluated using the new caries detector dye by the color evaluation method, a laser fluorescence device, DIAGNOdent® (KaVo, DIAGNOdent) and the bacterial method. Twenty-one cases of coronal dentin caries (eight human extracted molars) were divided into two groups. The carious lesions were removed by two examiners using the new caries detector dye until the color of the dentin surfaces was not stained. Then, the dentin surfaces were evaluated using the DIAGNOdent, images of the surfaces with a color-matching sticker were acquired using a CCD camera, and dentinal tissue samples were collected with a new round bur. Corrected L*, a* and b* values of the surfaces (CIE 1976 L* a* b* color system) were calculated from the color changes of the stickers in the images. On the other hand, bacterial DNA in dentinal carious tissues was detected by the polymerase chain reaction (PCR) using the universal primers based on the nucleotide sequences of a conserved region of the 16S rDNA. The intra-class correlation coefficients of the corrected L*, a*, b* and DIAGNOdent values were 0.16, 0.18, 0.86 and 0.51. There were significant differences between b* values of two examiners and between DIAGNOdent values of them (p<0.05). In eight of the 21 cases, bacterial DNA was found in the dentinal tissues after removal of carious tissues. The results suggest that the objectivity of caries removal using the new caries detector dye, Caries Check®, with visual inspection is not high.

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Bone morphogenetic protein (BMP) is known to stimulate the differentiation of pulpal cells into odonto-blasts and the formation of reparative dentin. This study was conducted to investigate the ability of hard tissue formation after direct pulp capping with mineral trioxide aggregate (MTA) containing BMP. Cavities with an exposed pulp area were prepared in the first molars of Wistar rats. After irrigation using alternating solutions of 10% sodium hypochlorite and 3% hydrogen peroxide (chemical surgery), the pulps were capped with either MTA containing 5wt/wt% BMP (BMP-MTA) or MTA alone, and these cavities were sealed with Super Bond (Sun Medical). After 7, 14 and 21 days, the rats were euthanized and the jaws removed. The samples were fixed in 10% neutral-buffered formalin solution, decalcified in Plank-Rychlo, embedded in paraffin and sectioned. The teeth were stained with hematoxylin-eosin for histological examination of pulpal changes. Histopathological evaluation demonstrated thicker dentinal bridge with BMP-MTA than MTA. The hard tissue formations with BMP-MTA had irregular or unclear dentinal tubules and had bone-like matrix formations including cells. No severe inflammation was observed underneath the bridges of any of the samples. The result suggests that MTA may release BMP sustainedly and be suitable as a carrier of BMP. The MTA containing BMP can be a biologically-functional direct pulp capping material.

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The purpose of this study was to determine the protein components of enamel tuft of porcine mature enamel and to investigate its formation processes. During demineralization of mature enamel with 0.5mol/l acetic acid, the insoluble structure, which includes the enamel tuft, along with the surface of the dentin was collected with tweezers. Since the collected enamel tuft still contained minerals, it was further demineralized with acetic acid and divided into soluble and insoluble samples. The freeze-dried samples were analyzed by SDS electrophoresis, mass spectrometry and Western blotting. From silver staining following electrophoresis, many protein bands in the enamel tuft were observed after demineralization with acetic acid. Mass spectrometry and Western blotting identified these bands to be mainly blood proteins (albumin, α-2-HS-glycoprotein and hemoglobin) and a small amount of enamel proteins (amelogenin, enamelin and sheath protein); degraded fragments of the blood proteins were also found. Therefore, the blood proteins reside in the enamel tuft itself, and do not contaminate the sample during preparation. The origin of albumin found in the enamel tuft was further investigated by examining several immature enamels using Western blotting. Albumin was only found in the highly mineralized enamel layer at the enamel-dentin junction, and not at the secretory, transition and maturation stages of the enamel and dentin. These results suggest that blood invades the enamel at the initiation stage, which corresponds to the highly mineralized enamel layer, and that the blood proteins cannot be degraded by enamel proteinases, allowing them to condense in the enamel tuft during crystallization.

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Cemental tear causes rapid localized destruction of periodontal tissue, but the mechanism remains unclear. Debridement is necessary to remove the bacteria adhered on the root surface, however, debridement in the absence of bacterial adhesion may inhibit the reattachment of the residual periodontal ligament around the fractured surface. This retrospective clinical study was performed to investigate the feature of bacterial adhesion at the root surface of the fractured site or fractured fragment in the case of cemental tear. Eight teeth from 8 patients were diagnosed with cemental tear. The probing depth (PD), bleeding on probing (BOP), suppuration, and rate of bone resorption were measured using dental radiography both before and after the occurrence of the cemental tear. The degree of bacterial adhesion at the root surface of the fractured site or fractured fragment was observed using a scanning electron microscope (SEM). Six patients had visited the hospital before the occurrence of the cemental tear; for these patients, we compared the clinical findings before and after the cemental tear. The appearance of BOP or suppuration, deepened PD, increased rate of bone resorption, and marked periodontal tissue destruction were observed after the cemental tear. A large amount of calculus and considerable bacterial adhesion were observed in 2 cases, a little calculus in 1 case and neither bacteria nor calculus in the remaining 3 cases, at the fractured fragments. For the 2 of the 8 cases, the root surface of an extracted tooth was examined: in 1 case, a high degree of bacterial adhesion was observed, in the other case, neither bacteria nor calculus at the root surface and periodontal ligament tissue around the root surface of the fractured site was observed. The findings of this study indicate that cemental tear may promote advanced periodontal tissue destruction, but bacteria may not always intrude into and adhere to the gap between the root and fractured fragment. If debridement is performed inadvertently without considering the presence of bacterial adhesion, the healing of periodontal tissue may be inhibited because of residual periodontal ligament damage of the root surface.

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The purpose of this study was to assess the polymerization shrinkage characteristics of experimental resin composites. In order to measure the volumetric shrinkage, each material was placed in a mold and extruded into a waterfilled dilatometer. The specimens were then light-irradiated using a curing unit with the power density adjusted to either 100 or 600mW/cm². For the speckle-contrast measurement, each resin composite was condensed into a glass tube and irradiated. The laser-speckle field was recorded in a digital frame as a function of time. When the power density was adjusted to 100mW/cm², the average volumetric shrinkage ranged from 1.80 to 3.91%, and when the power density was adjusted to 600mW/cm², the shrinkage ranged from 3.18 to 5.42%. The speckle-contrast measurements revealed changes in the pastes due to the polymerization of the resin composites that were greater than those obtained with the water-filled dilatometer.

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Although the histological changes in tooth enamel following Er: YAG laser application have been extensively studied, the acid resistance and remineralization of tooth surfaces after laser application have not been evaluated. In the present study, tooth surfaces following Er: YAG laser application were observed by quantitative light-induced fluorescence (QLF) to ascertain the effects of laser output and water irrigation on the remineralization of tooth surfaces following laser application. The following results were obtained. 1. Following Er: YAG laser application, as the laser output increased, ΔF and ΔQ decreased, and area increased. 2. At all outputs, with or without water irrigation, ΔF, area and ΔQ changed towards remineralization depending on the duration of soaking in the remineralization solution. 3. The remineralization reactions were more favorable with water irrigation compared to that without water irrigation. The above results suggest that QLF is a useful observation method for determining the prognosis of tooth surfaces following Er: YAG laser application.

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