In addition to the antimicrobial action produced by the oxidizing action of ozone, the tissue activation action of ozone can be applied in dentistry, with focus placed on its effectiveness as an antimicrobial, anti-inflammatory and hemostatic agent. We investigated the potential for using ozone water in the cleaning and disinfecting of artificial teeth and periodontal pockets, and as a cleaning fluid for root canal treatment. Recently, the Ozony Tron®, an ozone generator which produces ozone from available oxygen, was developed. This device does not require an oxygen tank to produce ozone, it has good portability due to its small size and weight, and it safely degrades the ozone gas released into oxygen, making it well suited for use during house calls. In this study we evaluated the clinical application of ozone gas treatment for infected root canals. From 155 devitalized teeth, where a positive culture was obtained in the root canal culture prior to enlargement of the root canal, there were 250 root canal samples on which the authors performed a routine root canal treatment following the enlargement standard (Yasuda's guidelines standard). After enlargement and preparation, 130 root canal samples were confirmed to have positive cultures, and these were the sample teeth used for this investigation. The sample teeth were randomly selected, and 88 root canals received ozone gas treatment and the remaining 42 root canals were irrigated alternately with Neo Cleaner and 3% oxydol and used as control teeth. Aerobic cultures were taken immediately following treatment, and a second culture test was taken during the patient's next visit before starting treatment, and these results were used to produce our findings. Moreover, we also used X-rays taken prior to surgery to investigate whether there was a correlation between presence of root lesions and ratio of positive cultures obtained. Results obtained were as follows. 1. Of the 250 root canals, we obtained a positive culture solely in root canal enlargement in 120 (48.0%). 2. Among the 88 cases where ozone gas was used, 42 root canals (47.7%) indicated no microbes, and of these, 10 root canals (11.4% of all cases) continued to have a negative culture into the second test. 3. In the cases with alternate irrigating, of the 42 root canals, 36 (85.7%) showed no microbes, and of these, 21 root canals (50.0% of all cases) continued to have a negative culture into the second test. 4. The correlation between radiolucent findings of the root and the ratio of positive cultures obtained indicated that, regardless of the presence of root lesions, the positive culture ratio for cases where ozone gas was used remained at approximately 50%. In cases where alternating irrigation was used, the positive culture ratio for root lesions (-) was 100%, (±) was 91.0%, and (+) was 64.0%.

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Based on the results of our previous research concerning the prevention and control of nosocomial infection in daily dental practice, the present study investigated the consciousness of dental practitioners on countermeasures for infection control of nosocomial infection in dental office management. A questionnaire survey on prevention and control of nosocomial infection was conducted for 744 dentists, namely, the members of the dental association in Yamaguchi Prefecture. The questionnaire contained 13 questions: an age of objective dentists, prevention and control of nosocomial infection in dental office management, and so on. The response data were collected and statistically analyzed using Spearman's ρ-test to assess the correlations among the responses for all question items. The major outcomes were as follows: 1. The response rate to the whole questionnaire was 24.2%. Followings were the alternatives with majority votes for the representative question items: the most commonly used disinfectant was "Alcohols" (33%), and the method of sterilizing or disinfecting dental handpieces was "Wiping only with ethyl alcohol" (34%). Thus, these data demonstrated that a number of dentists might not completely perform infection control in ideal ways. 2. While, the way of sterilizing dental tools was "Using autoclave" (93%), vaccine inoculation against the hepatitis B virus was "Already inoculated before" (61%), and the way of educating dental staff on prevention and control of nosocomial infection was "Teaching dental staff personally by dentists themselves" (60%). Thus, most of the dentists seemed to understand the importance of infection control in dental office management. 3. The results of correlation analyses demonstrated that younger dentists tended to manage only blood- and saliva-adhered burnable trash as biologic and infectious waste in the dental clinic, however, they were positive towards sterilizing dental handpieces, and vaccine inoculation against the hepatitis B virus. Furthermore, dentists with a clear awareness of the importance of Universal (Standard) Precautions were generally positive towards using effective disinfectants, sterilizing or disinfecting dental handpieces, disinfecting impressions, cast models and wax bites, vaccine inoculation against the hepatitis B virus, setting up a manual of countermeasures for nosocomial infection control, and attending training for nosocomial infection control. These results indicate that increasing awareness and training opportunities for dentists in the prevention and control of nosocomial infection, as shown in documents of the Ministry of Health, Labour and Welfare, might improve the environment in the dental offices of general practitioners.

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Even after discolored teeth have been treated with whitening agent, discoloration occurs again. The causes of tooth discoloration are various. Extrinsic discoloration is caused by deposition of external pigments on the tooth surface. Tooth whitening roughens the surface of tooth enamel. So, we hypothesized that the whitened tooth surface is highly contaminated by pigments compared with the non-whitened tooth surface. The purpose of this study was to determine the dye penetration into pre-whitening and whitened teeth. Twenty-four extracted human teeth were used in this study. The tooth color was measured by ShadeEye NCC. Each tooth was soaked in coffee for 24 hours, then the color of the stained tooth was measured. The stained tooth was treated with Shofu Hi-Lite (35% hydorogen peroxide) as an office whitening system and PolaNight (l6% carbamide peroxide) as a home whitening system at three weeks. The color of the tooth was measured every week. Then the whitened tooth was soaked in coffee, and the recurrence of dislocation was investigated. The values of L*, a* and b* were determined, and the color difference was calculated using the formula ΔE*ab=[(ΔL*)²+(Δa*)² +(Δb*)²]^1/2. The value of L* was observed to decrease after soaking in coffee, then the value of L* was increased by both of the office whitening and the home whitening. A slight reduction of L* was observed due to the recurrence of discoloration tooth. The color difference (ΔE*ab) of the tooth before and after staining with coffee was 10.22±1.62 in the office whitening group, and 10.85±3.35 in the home whitening group. The value of ΔE*ab between whitening and relapsing operation was 1.59±1.02 in the office whitening group, and the color difference was 4.76±2.37 in the home whitening group. These results suggested that the whitened tooth had resistance to staining with pigment.

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This study investigated the effect of 10% carbamide peroxide whitening agent on the elastic modulus, surface hardness, and surface texture of bovine dentin. Dentin specimens were trimmed to a size of 4×4×1mm. Whitening agent was splashed on to the specimens which were then stored at 37℃, 80% RH for 1 h, followed by rinsing with tap water. The procedure was done for a period of 56 days. Elastic modulus and Knoop hardness measurements were done immediately after the whitening, and at 7, 14, 21, 28 and 56 days after the start of treatment. For specific specimens, they were treated for observation with scanning electron microscopy. The results were as follows: 1. No changes in elastic modulus of dentin treated by the whitening agent were observed. 2. No changes in Knoop hardness of dentin treated by the whitening agent were observed. 3. Gradual increases in pH of dentin treated by the whitening agent were observed. 4. After the whitening procedure the smear layer was removed but no structural change was observed.

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The purpose of the present study was to evaluate the difference in the condensation of gutta-percha point depending on the types of spreaders in curved root canal models. Root canal obturation was performed by the lateral condensation method using 8 types of spreaders of different materials and sizes in curved root canal models made of resin with taper of 6/100 under the assumption that root canal preparation was conducted by using an engine-driven rotary instrument. Specifically, root canal obturation was carried out according to the lateral condensation method using the following spreaders: 2 types of stainless steel spreaders by DentalEZ Inc. (Star Dental D11T [S-D11T], and Star Dental D11[S-D11]); 4 types of Ni-Ti spreaders by Roeko Inc. (NiTi #15[R-15], NiTi #25 [R-25], NiTi #35[R-35], and NiTi D11T[R-D11T]); and 2 types of Ni-Ti spreaders by Brasseler Inc. (Naviflex NT D11T[B-D11T], and Naviflex NT 4SP[B-4SP]). The difference of condensation by each of these spreaders was evaluated by determining the ratio of gutta-percha point (gutta-percha condensing ratio) in the CT image of the root canal as seen at each of the positions 1, 2, 3, 4, 5, 6 and 7 mm from the root apex as taken by micro-focus X-ray CT. The following results were obtained. The average values of gutta-percha condensing ratio in the total CT images taken at the positions of 1 to 7 mm were : 93.9% in S-D11T spreader, being the highest, followed by B-D11T(93.7%), S-D11(86.1%), R-25(85.3%), R-D11T(85.2%), R-15(82.9%), R-35(76.8%) and B-4SP(76.2%), in decreasing order, and root canal seal was insufficient. It was found that the influence of the type of spreader on the gutta-percha condensing ratio was highly significant. In the gutta-percha condensing ratio as seen in the CT images at the positions of 1 to 7 mm, S-D11T showed a high value of 90.8% or more at the position of each of the CT images, and B-D11T showed a high value of 90.5% or more. In contrast, R-35 showed a low value of 65.9% at the position of 6 mm, and B-4SP also exhibited a low value of 69.4% at the position of 4 mm. It was found that the condensing ratio decreased in a form similar to the shape of a ship's hull. Also, in R-25, R-15, R-D11T and S-D11, local decrease of the condensing ratio was seen. These results reveal that, when selecting a spreader for a curved root canal, it is essential to put priority on the diameter of the spreader and on the insertion property and condensation property of the spreader to the root canal by taper rather than the flexibility of the material used.

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Root canal procedures may sometimes result in postoperative pain for a long time. In these clinical conditions, neuropathic pain disorders may occur as a result of dysfunction with nerve injury, and management tends to be intractable. We report here two cases of lingering tooth pain after a root canal procedure, and the clinical examination could be diagnosed as neuropathic pain disorders. These two cases were characterized by prolonged periods of burning pain in the tooth though there was no obvious source of local pathology, and seemed to be different from conventional intractable periapical disease. In managing neuropathic pain disorders following a root canal procedure, it is important to use diagnosis criteria to evaluate neuropathic tooth pain after confirming which part caused inflammation in the root canal. Further studies of the clinical criteria for neuropathic pain disorders following root canal procedures are needed.

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Adiponectin is an adipocyte-specific hormone that plays an important role in glucose regulation via its receptors 1 (AR1)and 2 (AR2). Recently, it has been reported that adiponectin is expressed in primary osteoblasts and promotes cellular proliferation and differentiation. In this study, we investigated the role of adiponectin in the differentiation and calcification of preodontoblasts (MDPC-23) in order to examine the usefulness of adiponectin as a dental pulp capping agent. Expressions of adiponectin, AR1 and AR2, were observed in MDPC-23. Addition of adiponectin into medium significantly increased the proliferation and alkaline phosphatase (ALP) activity compared to those of control cells, and upregulated the expression of bone formation-related genes, such as osteocalcin and osteopontin. Furthermore, accelerated calcified nodule formation was found in adiponectin-treated cells after 8 days. Pretreatment with mitogen-activated protein (MAP) kinase inhibitors, SB20358 and SP600125, suppressed the increase of ALP activity, suggesting that the differentiation to odontoblasts is mediated via p38 and JNK signal transduction pathways. These results suggest that adiponectin stimulates the differentiation of preodontoblasts into odontoblasts via MAP kinase cascade and might be useful as a dental pulp capping agent.

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The surface reaction type pre-reacted glass-ionomer (S-PRG) filler confers the ability to release fluoride and other ions when added to various filling materials including resin composites. In this study, some properties of a prototype S-PRG filler-containing root canal sealer (S-PRG sealer; Shofu Inc.) were evaluated. A zinc oxideeugenol sealer (PulpDent root canal sealer) was used as the control material. The coronal sealing ability of the test and control sealers, used with or without guttapercha points, was assessed with a dye penetration test where the penetration of basic fuchsin at 1-, 3- and 5-mm levels from the canal orifice was scored after 60 days of immersion. Distribution of F, Sr and B in the root canal wall dentin was mapped at 7 and 60 days after root canal filling by means of electron probe microanalysis. The antibacterial activity of fresh and set (12h after mixing) sealers against Enterococcus faecalis, Propionibacterium acnes and Actinomyces israelii was examined with an agar diffusion method. The results were as follows: 1. When dye penetration scores were compared, no significant differences were observed at each level (Kruskal-Wallis test, p>0.05). 2. Distribution of F and Sr was detected along the root canal dentin in contact with the S-PRG sealer, although this was not observed for the PulpDent sealer. 3. Both sealers of both fresh and set preparations showed antibacterial activity against P. acnes and A. Israelii, whereas activity against E. faecalis was not detected. It was concluded that the prototype S-PRG sealer has the ability to release F and Sr, and that the coronal sealing ability and anti-bacterial capacity of the S-PRG sealer are comparable to those of zinc oxide-eugenol sealers.

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Many adhesives with high bonding strength have been developed and applied in the biomedical field. These adhesives, however, have been used only for bonding between soft tissues. We developed a novel tissue adhesive (TAD-Albumin glue) consisting of tartaric acid derivative (TAD) and human serum albumin (HSA). The TAD-Albumin glue hardens by the amide bonding of HSA and TAD. It has been confirmed that the TAD-Albumin glue can combine with collagen fibers in the same way. Therefore, the TAD-Albumin glue, after being applied properly to exposed collagen fibers on the root surface, could mediate the binding between connective tissue and root surface. This study was designed to examine the bonding activity of the TAD-Albumin glue applied between dentin and soft tissue, and to evaluate its biocompatibility in vivo. To examine whether tooth surface treatment affects the bonding strength or not, human dentin chips were treated with saturated citric acid or 10% EDTA for 1, 3, and 5 min, and others were non-treated. Treated or non-treated dentin chips were bonded to columnar resin with stationery adhesive. Then the TAD-Albumin glue was applied to the dentin chip surface, and collagen-coated columnar resin was located on the chips. The bond strength was measured with a tensile machine. For histological examination, the TAD-Albumin glue was applied to the dentin chips treated with saturated citric acid for 3 min, then the chips were subcutaneously inserted into the back of forty 10 week-oldmale Wistar rats. To evaluate biocompatibility, the dentin chips were removed together with surrounding tissues on 0, 3, 7, 21 and 42 days after operation, and prepared for hematoxylin and eosin (H-E) sections for histological observation. The experimental group treated with saturated citric acid for 3 min had significantly higher bond strength than the non-treated group (p<0.0l). Histologically, the TAD-Albumin glue maintained bonding activity for 7 days after operation. No remarkable inflammatory cell infiltration was observed around the dentin chips. In conclusion, this study suggests that: 1. Citric acid treatment increased the bond strength of TAD-Albumin glue. 2. The TAD-Albumin glue maintained bonding activity for 7 days without tissue damage.

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We have developed and applied a new electronic portfolio system to educate 65 dental residents for postgraduate clinical training in Okayama University Hospital of Medicine and Dentistry since the 2006 academic year. The purpose of this study was to examine the situation of postgraduate clinical training concerned with conservative dental treatment by using our electronic portfolio system in order to improve the postgraduate clinical training program at our hospital. At first, the number of patients whom the dental residents had treated was examined. Next, the records related to conservative dental treatment that the residents had put in the electronic portfolio system were exported and divided into three groups: restorative treatment, endodontic treatment and periodontal treatment, and the details were analyzed. The average number of patients for the period of their internship was 17.0±4.9 persons and the total number of records in the electronic portfolio system was 23,911. The records concerned with conservative dentistry accounted for 47.3% (11,316 records) of the total. The frequency of the restorative, endodontic, and periodontal treatments were 9.4% (2,239 records), 9.8% (2,335 records), and 28.2% (6,742 records), respectively. Detailed analysis demonstrated that residents experienced over 10 cases of "root canal filling" and "scaling and root planing", and over 20 cases of "resin filling", "root canal enlargement and/or application", "periodontal tissue examination", "tooth brushing instruction", "sonic scaling", and "supportive periodontal therapy". The results demonstrated that the dental residents experienced conservative dental treatment with a frequency of over 50% (almost 50% of all dental treatments) during their postgraduate clinical training program in Okayama University Hospital of Medicine and Dentistry, and that they experienced over 10 cases of basic treatment procedures of conservative dentistry.

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With the increasing diverse needs of oral health care users in recent years, it is critical to provide high quality oral care. In order to integrate oral health care in welfare programs, more and more welfare centers are introducing dental health facilities. However, little information is available regarding the current situation of oral health care provided at welfare centers, and dental demands in the center. In the present study, a questionnaire survey was conducted in various types of welfare centers in order to understand the current situation of oral health care provided and dental demands in the centers. A questionnaire survey was conducted in a total of 1,309 centers in Saitama prefecture, including nursing care and welfare centers, and schools for the visually impaired, hearing impaired, and other disabled students. The questionnaire included the following items: 1. the current condition of the respondent and the center where he/she was working, 2. the current condition of oral health care provided in the center, and 3. information which is required by the center in order to facilitate coordination between the oral health care facility and users. The number of respondents was 331 (recovery rate 25.3%). The centers where respondents were employed included home nursing care centers, visiting nursing care centers, and welfare centers for the elderly. Only 206 of the 331 respondents (62.2%) answered that their center had a dental care provider with whom they could cooperate and coordinate. The main reason mentioned by the respondents for not having a dental care facility was "it is not obligatory." However, more than 80% of the respondents admitted the necessity of collaborating or cooperating with dental care facilities. Although the required oral health care information and cooperation items varied among different types of centers, the overall number of respondents who knew about "the relationship between oral care and aspiration pneumonia" and "the relationship between the whole body and oral diseases" was high. This suggested that the respondents were aware of the importance of oral health care for general wellbeing. Preferable coordination with dental care providers by welfare centers varied according to the type of center. Based on the results of the present study, it was confirmed that oral health care has become highly important in nursing care and welfare centers.

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This study attempted to survey the incidence of pulp calcification with age and the histomorphological cause of dead cells or microorganisms, and also to discuss structure and periodontal disease. The observed samples were 122 teeth which were noncarious but condemned for orthodontic or periodontal reasons. The occurrence and morphology of the pulp calcifications were examined with micro CT and then the calcifications were divided into three types: i)round or oval, ii)granule, iii)irregular type, respectively. Electron probe micro-analysis and transmission electron microscopy were mainly employed for the histological observation of each type of calcification. As a result, calcifications in dental pulp were found in about 40% of teeth examined with micro CT. The pathological inflammations caused by bacteria, cell debris, and/or encapsulation of foreign bodies were observed histologically in the dental pulp tissue in which false denticles were found. Furthermore, the processes of irregular types of calcification, which were 1-2 microns flattened oval bacterial-like structures ranging several times, its calcification spreading out into the surroundings, and/or other oval types of calcification consisting of aggregate of 30-40 nm small calcified granules, were observed. Overall results suggested that the bacteria invaded into dental pulp in cases of serious periodontal disease. Useful information for the treatment of complications of dental pulp and periodontal diseases was obtained.

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The CEREC computer-aided design/computer-aided manufacturing (CAD/CAM) system enables onevisit restorative treatment by means of chairside fabrication of all-ceramic restorations. The purpose of this in vitro study was to evaluate the adaptation and marginal leakage of CEREC 3 laminate veneers with different incisal and marginal preparation designs. Forty extracted human maxillary anterior teeth were divided into 4 groups (n=10, each) and were prepared for labial veneers with two types of incisal preparation (window preparation and incisal overlap preparation) and two types of cervical margin location (enamel and dentin). Optical impression with a CCD camera was taken with a handheld technique from the powdered preparations. Ceramic veneers were fabricated and seated with a dual-cured resin cement (Panavia F2.0, Kuraray). Specimens were immersed in 0.2% basic fuchsin and stressed under a mechanical axial load cycle of 1.3 kgf, 98 cycles/min for 24 hours, and then cut linguo-labially through their center. Under a stereomicroscope, the cement thickness was measured at three points (cervical, central and incisal), and the presence of dye penetration within the ceramic-cement and cement-tooth interfaces was examined at two points (cervical and incisal). Results demonstrated that the mean cement thickness was less than 150/μm in all groups. The incisal overlap preparation groups showed significantly greater cement thicknesses at the incisal measuring point compared with the window preparation groups (p<0.05; one-way analysis of variance and Bonferroni/Dunn test). The enamel margin groups showed less marginal leakage at the cement-tooth interface of the cervical measuring point than the dentin margin groups, irrespective of incisal preparation designs (p<0.05; Kruskal Wallis and Mann Whitney tests). It was concluded that the incisal overlap preparation may cause increased cement thickness at the incisal area, and that the placement of enamel cervical margins may contribute to better seal of the cervical marginal area irrespective of different incisal preparation designs.

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In order to develop vital pulp therapy, it is important to establish an in vitro experimental system reflecting the odontoblast differentiation process containing terminal differentiation, i. e. mineralized dentin formation. Previously, we had established an in vitro culture system using dental pulp cells enzymatically isolated from rat lower incisors. This culture system can demonstrate characters of differentiated odontoblast-like cells forming mineralized dentin-like matrix. However, much about the mechanism of dentinogenesis remains to be researched. The purpose of this study was to analyze the characters of mineralized nodules formed in the cell layer of dental pulp cells, and to determine whether or not this culture system can be a useful tool to examine dentinogenesis. During the 20-day culture period, the cells began to form mineralized nodules from day 10, the nodules became larger by day 20, and the nodules surrounded the cells expressing alkaline phosphatase (ALP). ALP activity in the cell layers was maximum on day 15, and gradually decreased on day 20. The calcium content in the layers was low by day 10, and significantly increased from day 15. Real-time PCR demonstrated that the expression of bone gla protein (BGP) was first determined on day 15 and drastically increased on day 20, and that dentin sialo protein (DSPP) gradually increased to day 15, and remarkably decreased on day 20. Immnohistochemistry was performed in the sections prepared from the cell layers embedded in paraffin, and antibodies used in the stainings were anti insulin-like growth factor (IGF)-1, anti bone morphogenetic protein (BMP)-4, anti DSPP, anti BGP, and anti osteopontin (OPN). The matrices of mineralized nodules were strongly stained with all antibodies. These results demonstrate that this culture system is useful for studying the odontoblast differentiation process.

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Successful manipulation of instruments clinically requires instinctive dexterity based on a thorough knowledge of dental anatomy. In round and nearly straight roots of upper central incisors in which the canals are centered in the dentin body of the teeth, the wall thickness is approximately equal in the labiolingual and mesiodistal cross sections. However, the wall thickness of curved canals of molars with two or three roots can be irregular and variable. The presence of a thinner portion or danger zone of the root structure toward the furcation areas of molars had been poorly described in tooth morphology and even in textbooks on endodontics. The purpose of this study was to precisely measure the thickness of root morphology available for root canal orifice preparation in the mesial roots of lower first molars. We investigated macroscopically the bifurcated root forms viewed from the mesial and distal aspects of 109 human lower first molar teeth. The lengths of all teeth were measured and furcation morphology with root concavities was examined. Modified dental stone replica models of the roots were transversely sectioned at the furcal portion and mid-mesial root length levels to the long axis. The external form of the replica samples was traced at 2×magnification. The mesio-distal and bucco-lingual length (distance) were examined. The results were as follows: 1. Type I with the presence of signs of bifurcation at the root tip was found in 22.9% of mesial roots and 4.6% of distal roots. Type II, III and IV with a single root were respectively found in 22.0, 12.8%, 39.4, 41.3% and 15.6, 41.3%. 2. Regarding the furcal aspect of the root, deeper concavity was found in 84.4% of the mesial roots and 41.3% of the distal roots. 3. The average mesio-distal dimension of mesial roots was 2.68mm in the bifurcation with root concavity and 2.01mm at halfway between the cervical portion and the apex. The minimum dimension was 1.98mm and 1.06mm at the thinnest portion of the mesial roots. There was a significant difference between morphological patterns of mesial and distal roots.

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Recombinant human bone morphogenetic protein (BMP)-2 is known to induce significant regeneration of bone, but the influence of osteoporosis on bone formation is not understood. The aim of this study was to investigate the influence of osteoporosis on bone formation by histopathological and histometrical evaluations. Five-week-old KO OCIF/Jcl (homo) mice (osteoporosis group) and C57BL/6NJcl mice (normal group) were used. Atelocollagen gel with 0, 1, 5, 10 and 15 μg/ml BMP-2 were prepared and injected into the periosteum of the mice's cranial bone. Histopathological observation and histometric measurement of new bone and bone density were performed. The Mann Whitney U test was used for statistical significance. Both groups increased new bone in a concentration-dependent manner. At BMP concentrations of 0 and 1μg/ml, neither group showed new bone, and at BMP of 5 and 15μg/ml, the osteoporosis group showed significantly more bone than the normal group (p<0.05). Bone density was significantly lower in the osteoporosis group than in the normal group at BMP 5,10 and 15μg/ml separately (p<0.05). As a result, it was concluded that the amount of new bone induced by BMP-2 increases and the bone density decreases in osteoporosis.

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