This study evaluated the efficacy of fine Surface Prereacted Glass-ionomer (S-PRG) powder as a medicament for dentin hypersensitivity. Bovine dentin specimens with simulated hypersensitive surfaces were constructed through 10% phosphoric acid etching and hydroxyapatite paste abrasion. The surfaces of these abraded specimens were scrubbed with the fine S-PRG powder (S-PRG group). For the comparison, others were treated with a powder of glass-ionomer cement: fluoroaluminosilicate glass powder (FAS group). An untreated group was prepared as a control. Before and after immersion in demineralizing solution, surface textures and the occlusion of dentinal tubules were observed and assessed by SEM. After demineralization, EPMA analyses were also carried out to detect elements on the treated and fractured dentin surfaces. Mineral contentprofiles of the lesions and the total amount of mineral removed, expressed as Integrated Mineral Loss (IML), were obtained by transversal microradiography in order to measure the effect of treatment of the underlying dentin, against demineralization. SEM observations revealed that the dentin surfaces of the S-PRG group were covered with powder and the dentinal tubules were completely occluded with fine particles, even after demineralization. On the contrary, dentinal tubules of the FAS group were only partially occluded, and there was no powder residue in evidence at all after demineralization. EPMA analysis showed that deposits of calcium, fluoride and aluminum were detected to a higher degree in the S-PRG group in comparison with the FAS group. Calcium was characteristically detected at the orifice of dentinal tubules, which is indicative of the anti-demineralizing effect of the fine S-PRG powder. The mineral profiles of the S-PRG and the FAS groups were different from that of the control group; in particular, the S-PRG group showed distinct surface layers with a thick and high % volume of minerals. The S-PRG group also indicated a significantly lower IML compared with the control and FAS groups (p<0.05). These results suggest that fine S-PRG powder will have a superior, occluding effect on opened dentinal tubules and will provide acid resistance to the underlying dentin. Fluoride and other minerals in concentrated release from S-PRG powder may contribute to remineralization in the tubules, and occlusion, over a long period. These characteristics lent much weight to the premise that the application of fine S-PRG powder is an effective medicament for dentin hypersensitivity.
Our previous study showed that microleakage occurred mainly at the incisal margins of the wedgeshaped cervical cavities when flexural load cycling (labio-lingual displacement) was repeatedly applied to the incisal edge of the tooth, whereas it mainly occurred at the apical margins of the U-shaped cavities. Accordingly, stress distribution produced by occlusal forces as well as bond strength to enamel and dentin and polymerization contraction may have an influence on the microleakage pattern. The purpose of this study was to investigate the stresses induced along the cavity walls of cervical resin composite restoration under mechaanical load using 2D finite element analysis. Two finite element models of the incisor were developed: the wedge-shaped cavity model, and the U-shaped cavity model. These finite element models were developed using a finite element analysis software package "Ansys 7.0". Enamel, dentin and resin-based composite were assigned Young's moduli of 41,400, 18,600 and 10,000 MPa, respectively, and Poisson's ratios of 0.3 and 0.3, respectively. The pulp chamber was modeled as a void bacause of its negligibly low Young's modulus. Meshing was carried out using linear, eight-node isoparametric elements. The wedge-shaped cavity model consisted of 3,047 nodes and 907 elements. The U-shaped cavity model consisted of 4,106 nodes and 1,289 elements. All the nodes in the bottom row of the model, 2mm below the apical margin of the restoration, were fixed in both the X and Y directions. Labio-lingual displacement of 1 mm was applied to the incisal edge of the models. The materials comprising the model were assumed to be isotropic and homogeneous. Outputs were presented in the form of stress contour plots of these models. The shear and normal stresses generated at the adhesive interfaces were calculated. The stress contour in the wedge-shaped cavity was similarly observed in the tooth with the U-shaped cavity, excluding around the cavity. The incisal wall of the wedge-shaped cavity had greater normal (tensile) stress than the apical wall. The incisal wall of the U-shaped cavity had less normal (tensile) stress than the apical wall. The findings of this study have indicated that the stress distributions generated at the adhesive interfaces by mechanical load depend on the cavity forms. Moreover, the findings suggest that tensile stress participates in bonding failure and plays an important role in microleakage.
The purpose of this study was to investigate the effects H2O2 treatment on the mineralization ability of human dental pulp (HDP) cells. Reactive oxygen species (ROS) given off as by-products of cell metabolic activity are known to cause various diseases. However, when produced in small amounts, they are reported to stimulate cell proliferation, possess antiseptic properties and function in cell signaling systems. We have reported previously that laser irradiation increases H2O2-derived free radical production and mineralization ability in HDP cells. In this experiment, we used the dimethyl sulfoxide (DMSO) as a scavenger of hydroxyl radicals. HDP cells were treated with 1×10-3 mol/l, 1×10-4 mol/l, 1×10-5 mol/l, 1×10-6 mol/l, and 1×10-7 mol/l of H2O2, 1×20-2 mol/l of DMSO, and a mixture of 1×10-2 mol/l DMSO and 1×10-5 mol/l of H2O2. Non-treated cells served as a control. Gene expression of BMP-2 and ALP in cells treated with 1×10-5 mol/l H2O2 was greater than that in the others. The ALP activity and production of BMP-2 were highest in cultures treated with 1×10-5 mol/l H2O2. Calcified nodule formation was increased on day 28 by the treatment with 1×10-5 mol/l H2O2. These results suggested that mineralization of HDP cells was enhanced by 1×10-5 mol/l H2O2.
This study investigated the effect of various layer thicknesses on color changes of light-cured composite resins. Two light-cured composite resins with different shades, Estelite Σ(ES, Tokuyama Dental, Shade; OA2, A2) , and Gradia Direct (GD, GC Corp., Shade; AO2, A2), were used. Resin disks (8 mm in diameter) with different thicknesses (0.1, 0.2, 0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 3.0 and 4.0mm) were prepared. Colorimetric values of the specimens were measured immediately after curing against a three-colored plate using a fast spectro-photometer (CMS-35FS/C, Murakami Shikisai). The CIE L*a*b* color system was used for determining of the color. The data was subjected to Tukey's HSD test (p=0.05). The results were as follows: 1. The thickness of the resin composite which was not influenced by the white and black colored plates as background was 2.0mm for OA2 shade of ES and GD. These opaque shade resins exhibited acceptable masking effect against any background colors. 2. Two layers that could match the color of the A4 plate as well as reproduce the A2 color were obtained with the combination of 1.5 mm thickness of GDAO2 shade and 0.2 or 0.3mm thickness of GDA2.
A transient sensitivity during tooth whitening is generally reported to occur in 30% of patients, and tooth sensitivity sometimes leads to discontinuation of treatment. To prevent tooth sensitivity, application of sodium fluoride prior to use of whitening agents is recommended. This study evaluated the influence of fluoride containing dentifrice on the whitening effect of the agents. Eight human teeth were selected and each tooth crown was sectioned into two halves in the mesial-distal direction. One half of the sectioned tooth was brushed with fluoride containing dentifrice (900 ppm) and the other half was used as a control. After brushing, these specimens were treated by the 10% carbamide peroxide whitening agents. Color change was measured using a spectro-photometer and evaluated by the CIE L*a*b*. Evaluations were performed at baseline and 7, 14, 21 and 28 days. The results were as follows: 1. While L* value increased, a* and b* values decreased during tooth whitening. 2. Color change during tooth whitening was not affected by the use of a fluoride containing dentifrice. 3. Enamel surface texture during tooth whitening was not affected by the use of a fluoride containing dentifrice.
Dens in dente, or dens invaginatus, is a developmental anomaly of the hard tissues of teeth. Endodontic treatment of a dens in dente in which the invagination communicates with the periodontal ligament is very difficuls. Therefore, most clinicians recommend extraction. Here, we present a case of successful conservative endodontic therapy by apexification of an immature permanent tooth with dens in dente. An 11-year-old girl was referred for endodontic treatment of a right mandibular lateral incisor with dens in dente. Radiographic observation revealed that the invagination communicated with the periodontal ligament (Type III, according to Oehlers' classification). Computed tomography (CT) was used to further examine the anatomical form of the root canal. The imaging information from CT was helpful for endodontic treatment. Two root canals including a main root canal, and the invaginated root canal of the incomplete root were observed. Pulpectomy was performed in the main root canal, and apexification was attempted after the invaginated root canal was treated endodontically. An apical hard tissue barrier was formed 14 months after treatment, after which the root canal was obturated by gutta-percha. At the 1-year recall examination, the tooth remained asymptomatic and reduction of the lesion was evident in the radiograph.
Several types of fluoride-releasing cements are currently used as luting materials. This study evaluated the following properties of five fluoride-releasing luting cements: 1) pH of liquid components, primers and unset mixtures; 2) surface ultrastructural changes following exposure to acetic acid and acetone; 3) ultrastructure of enamel and dentin surfaces treated with primers and unset cement mixtures; and 4) ultrastructure of and fluoride ion distribution along the cement-tooth interface. A glass-ionomer cement (HY-Bond Glasionomer CX, HBG), three resin-modified glass-ionomer cements (Fuji Lute, FL, HY-Bond Resiglass, HBR and Vitremer Luting Cement Fast Set, VT), and an adhesive resin cement (PanaaviaF 2.0,F) were examined. The pH was measured with pH test paper, and the ultrastructure and fluoride ion distribution were evaluated by scanning electron microscopy and electron probe microanalysis, respectively. Results obtained were as follows: 1. The pH of various cements was lower than 4. 2. All materials showed surface deterioration following exposure to acetic acid and/or acetone. These changes were minimal in VT and HBR following exposure to acetic acid and acetone, respectively. 3. Treatment of human enamel and dentin with the primer for PF (ED primer) caused surface demineralization as demonstrated by the exposure of enamel prisms and dentinal tubules, whereas such changes were less apparent following treatment with unset cements (HBG, HBR and VT), and the conditioner for FL. 4. Along the luting cement-dentin interface, HBG, FL and PF showed the formation of a narrow hybrid layer, whereas HBR and VT showed the formation of a gap. 5. All the test luting cements caused fluoride uptake by enamel and dentin, although PF showed comparatively little fluoride uptake. These results suggest that fluoride-releasing luting cements may contribute to the prevention of secondary caries along the restoration margin, although the surface deterioration and incomplete bonding may affect the longevity of restorations.
Fluoride-releasing composite resin and bonding materials have recently been developed for application during the glass-ionomer cement phase of treatment, This new generation of fillers exploits the acid-base reactions of fluoride re-charge and release. In this study, we applied these new bonding materials in dog to histopathologically investigate pulp response and evaluate cytotoxicity. This study was conducted based on the guidelines for animal experiments issued by Tokyo Dental College. A total of 71 test teeth were obtained from dogs aged older than one year including maxillary and mandibular incisors, canines, premolars and post-molar teeth. The test teeth were divided into two groups, an IB group, which underwent restoration with the new fluoride-releasing composite, and an LC group, which underwent restoration with resin-modified glass-ionomer cement. Teeth were collected after a short term '7 days) or a long term (90 days), subjected to hematoxylin-eosin doublestaining by the usual procedures, and then investigated histopathologically under a microscope to assess dentin and pulp responses. In addition, Hucker-Conn staining was conducted to determine the presence or absence of microbes in the cavities and dentinal tubules. We used the Millipore filter method to determine cytotoxicity. The new fluoride-release composite resin system demonstrated favorable pathological results confirming its safety in relation to dentin. The non-polymerization resin showed only a mild cytotoxic response. These results indicate that the new fluoride-releasing composite resin system can be applied as a restorative material with superior safety.
The objectives of this study were to perform 3-D reconstruction and analysis of accessory canal anatomy in the bifurcation area of the multirooted molar with respect to occurrence, location, frequency, running forms and terminus (opening) structure. The bifurcation area of a total of 47 extracted human mandibular molar teeth (23 first molars, 6 second molars, and 18 third molars involving 4 immature root teeth) was investigated with microfocus X-ray CT. These teeth had been stored in 10% formalin solution. The following results were obtained: 1. The crista interradicularis with presence of a distinct ridge (protuberance) in which there was an interconnection between the mesial root and the distal root was identified in the early development of the interradicular bifurcation of the formed molar tooth on 3-D reconstruction. In such areas small holes were seen extending from the dental sac of the tooth germ to the coronal pulp. Therefore, it must be true that accessory canals are present at the region where the promontory develops in the intermediate bifurcation. 2. Although these canals were observed in all 4 immature root teeth, they appeared to be absent in 32.6% of mature adult molars. In the immature teeth these canals appeared to run toward the region of the mesial canal orifice communication between the pulp and bifurcation region. In mature teeth, a multitute of these canals were present from the bifurcation region into near the dentinocementum junction. 3. As one of type IV, we indicated that numerous canaliculi might develop leading from pulp into the pulpal floor dentin and the root canal resulting from elaboration of so-called secondary dentin deposit. 4. Near the dentinocementum junction of bifurcation areas, one or a few accessory canals were sometimes seen as slit-shaped or small hole tissues. In many teeth an enamel dropletlike substance seemed to be present within these tissues.
Objective: This study examined the adhesive properties and trial manufacture of resin core shen it is applied to the infected root canal wall. Materials and Methods: The examined resins were: AC-1, AC-2 and AC-3, which contain an acid reaction fluoride inclusion of glass ionomer filler (S-PRG). Evaluations of bonding strength and bonding elasticity were performed. The flow value was calculated and an adhesion test of the resins was performed according to the ISO standard. The bacterial survivability on the root canal wall was analyzed by scanning electron microscope (SEM) and 4', 6-diamino-2-phenylindole dihydrochloride (DAPI). Results: A bacterial survivability on the root canal wall of 76% was confirmed by SEM and DAPI. In addition, a rate of concordance between anaerobiotic culture and DAPI of 86% was exhibited. However, neither infiltration nor pigmentation was observed between the root canal wall and resin core. Suitable seal and absence of gap was corroborated by SEM. The elemental components of the bonding materials were identified by energy dispersive X-ray micro analyzer. Conclusions: The simple confirmation of bacterial survivability by DAPI was effective and the trial manufacture of root canal resin core presented favorable behavior in infected root canal wall with physical properties similar to the dentin. Therefore, the clinical application of these materials could be possible.
Objective: This study examined the characteristics of flowable composite-resins containing improved S-PRG filler. Materials and Methods: The tested materials were Beautifil High flow F10 (BF10-resin) and Beautifil Low Flow F02 (BF02-resin), both of them containing improved S-PRG filler, and the control materials were Unifil Flow (Un-resin) and Metafil Flo (Me-resin). Resin blocks were prepared using a metal mold followed by their bonding on both upper first molars. The blocks were debonded at 8, 12 and 24 hrs, respectively and antiplaque test was carried out including SEM observation and energy dispersive X-ray micro analysis. Furthermore, observation of saliva proteins on each resin surface and albumin adsorption probe was performed. Concerning the cavity wall adaptability test, cavities were prepared in two different manners: by Er: YAG laser and diamond burr mounted in a high-speed hand-piece. Then the preparations were filled with the corresponding material according to each manufacturer's recommendation and the cavity wall adaptability was analyzed. Results: One of the most important findings was that BF10 and BF02-resing exhibited almost no bacterial adhesion. The energy dispersive X-ray micro analysis revealed the presence of elements such as Al, Si, and Sr of the improved S-PRG filler. Also, only in BF10 and BF02-resins the film layer was observed on their surfaces soaked in albumin solution. The albumin adsorption was higher in BF10 and BF02-resins than control materials. Overall, the cavity wall adaptation was suitable for all materials, unless BF02-resin showed a creck when the cavity was prepared by Er: YAG laser. Conclusions: BF10 and BF02-resins presented appropriate characteristics and were useful for the treatment of caries; moreover they offered an anti-plaque property suggestion that the application of these materials is suitable as a minimal intervention approach.
Biological analysis using pathological and immunohistochemical methods was performed to charify the mechanism underlying the resistance of chronic apical lesions to conventional therapy. Eighty cases of chronic lesions were classified into fourtypes: type I (granuloma surrounded by firm collage bundles), type II (granuloma with abscess formation), type III (granuloma with infiltration of numerous neutrophils) and type IV (scar tissue consisting of collagens). The collagenous capsulation of granuloma and scar tissue are considered to cause the intractable behavior. The collagenous tissues are obviously produced by the fibroblasts, which are a main component of the granuloma. The immunohistochemistry indicated that the proliferation of such fibroblasts is enhanced by basic fibroblast growth factor, which is mainly produced by macrophages infiltrated in the granuloma. Animal experiments using rats injected with Actinomyces suspension strongly suggested that the finfiltration of macrophages is promoted by Actinomyces components in the infected root canal. In addition, it was also suggested that the formation of foam cells, which are observed in chronic apical lesions, is related to Actinomyces components in the lesion.
The purpose of this randomized controlled trial was to investigate the efficacy of dietary supplementation with anotioxidative vitamins, vitamin (C(VC) and E(VE), for preventing progression of periodontal disease in nonsmokers. A total of 42 patients in periodontal maintenance were randomly assigned to the test group, VC (1,000mg/day) and VE (135mg/day) or the placebo group. Two subjects were dropped from the study due to incidental reasons. Plaque index (PII), clinical attachment level (CAL), probing pocket depth (PPD), gingival index (GI), blleding on probing (BOP), serum level of VC and VE, and several antioxidant levels from gingival crevicular fluid (GCF) were measured at baseline, 12 and 24 weeks following the supplementation. Serum VC and Ve levels in the test group increased significantly at 12 and 24 weeks. BOP and PPD were significantly improved (p<0.05) in the test group at 12 and 24 weeks. BOP and PPD were significantly improved (p<0.05) in the test group at 12 and 24 weeks, respectively, by the subject based analysis compared with the status at the baseline. The test group demonstrated a significant improvement against the placebo group in both GI and BOP at 12 and 24 weeks (p<0.05). VC and reduced glutathione (GSH) levels of GCF in the test group significantly increased at 12 and 24 weeks in comparison with the baseline (p<0.01). Although VE level of GCF significantly decreased from that at the baseline in the placebo group, no change was observed in the test group. Furthermore, in regard to the sites with no gingival inflammation (GI=0) at the baseline, significant increases in the change of GSH and VC levels of GCF were found in the test group compared with the placebo group (p<0.01 and p<0.05, respectively). The exacerbation of GI at these sites in the test group was significantly suppressed compared with that of the placebo group (p<0.05). As to the sites with gingival inflammation (GI≧1) at the baseline, there were no significant differences between the test group and the placebo group in the changes of these parameters. These results suggest that supplements of VC and VE may prevent periodontal disease in non-smokers during the periodontal maintenance period through controlling oxidative status in the periodontal tissues.
The purpose of this study was to evaluate the root configurations and the canal characteristics of two human extracted mandibular second molars respectively possessing an extra root by using a microfocus X-ray CT apparatus. The results were as follows: 1) The two teeth from persons of unknown age and sex were mandibular left second molars with the appearance of 5 cusps. It was not possible to clarify their occlusal fissure patterns such as Dryopithecus pattern due to apparent occlusal wear. 2) Although the teeth had two roots, the mesial and the distal, there was an extra root on one of them on the buccal side of the cervical-mid root stump. The distance from the cervical junction to the level of funcation was two to three millimeters. The extra root with a tiny single canal extended parallel to the long axis of the mesial root. The tooth showed 3 canals with 3 apical foramina. The extra root of the other tooth branched out on the lingual side of the near level of bifurcation between the mesial and distal roots. The tooth showed 4 canals with 3 apical foramina. The mesial root divided into 2 canals, but merged into 1 apical foramen. The extra root and canal were very slender. 3) The microfocus X-ray system was useful to examine rare puzzling supernumerary roots and their microscopic canals in mandibular molars. Dental practitioners should be aware of possible root canal variations in all teeth so that they can be treated successfully.
The aim of this study was to evaluate the clinical and microbiological effect of non-surgical periodontal therapy on metabolic control of Type 2 diabetics. The first report showed that there were significantly effective changes in the clinical and microbiological evaluation after non-surgical periodontal therapy in Type 2 diabetics and non-diaferences in the levels of HbA1C and glucose level of Type 2 diabetics. Therefore, to evaluate the effect of non-surgical therapy on inflammatory mediators, serum CRP, IL6 and TNF-αwere measured. Nine Type 2 diabetic patients (2 females and 7 males, 47-69 years, mean age 57.6 years) with moderate to advanced periodontitis and 9 matched healthy control patients (5 females and 4 males, 45-59 years, mean age 52.0 years) were selected. Serum CRP, IL-6 and TNF-α concentration were measured at baseline and three months after non-surgical periodontal therapy. Serum high-sensitive CRP was measured by using nephelometry, IL-6 and TNF-α were determined by sensitive enzyme-linked immunosorbent assay (ELISA). The serum concentration of CRP decreased from 5.02±7.38 mg/ml to 0.96±0.94 mg/ml (p=0.038) in Type 2 diabetics. Serum CRP concentration of non-diabetics was 0.43±0.27 mg/ml at baseline, and 1.01±0.99 mg/ml after non-surgical periodontal therapy. Serum IL-6 concentration decreased from 3.89±4.31 pg/ml to 1.84±1.51pg/ml (p=0.086) in Type 2 diabetics. Serum IL-6 concentration of non-diabetics was 1.22±1.44 pg/ml at baseline and 2.81±1.70 pg/ml after non-surgical periodontal therapy. Though serum TNF-α concentration was 0.99±0.86 pg/ml at baseline and 1.39±1.52 pg/ml in Type 2 diabetics after non-surgical periodontal therapy, serum TNF-α concentration of non-diabetics was 2.19±1.27 pg/ml at baseline and 3.74±3.81 pg/ml after non-surgical periodontal therapy. There were significant differences in the changes of serum CRP concentration and serum IL-6 concentration tended to decrease after non-surgical periodontal therapy, though there was no significant decrease in the change of serum TNF-α concentration after non-surgical periodontal therapy in Type 2 diabetics. There was a lower level of serum TNF-α in Type 2 diabetics than non-diabetics at baseline. It is reported that decrease of serum TNF-α concentration induce to improve in the insulin-resistance. These results suggest that improvement of periodontal inflammatory tissue induce to decrease of acute general inflammatory response, and helps to improve metabolic control of Type 2 diabetics who have been cured by internal medical therapy and diatary care.