The aim of this study was to develop an opeque resin that has a color shielding ability against colored dentin and does not influence the color of titanium dioxide was considered to increase the color shielding ability, and three types of materials -rutile, anatase, and apatite coating- were examined. The apatite coating was chosen as the opaquer to be mixed with low viscosity resin composite, because this type of material has the least influence on composite polymerization. Samples of opaque resin disks with mixing ratios of 0.50, 1.00, 2.00, 3.00 and 4.00%, and thicknesses of 0.25 and 0.50 mm were prepared. The color shielding ability and color differences were calculated from each color of coronal composite and the color that appeared from the composite which was laid on the experimental opaque resin to shield the colored dentin based on L*a*b* values with a colorimeter. As a result, a 0.50-mm-thick opaque resin disk mixed with apatite coating with a mixing ratio of 2.00% exhibited a good shielding effect and a lower influence on the color of the coronal composite.
We report two cases of the autotransplantation of teeth in a tooth-deficient region. The autotransplantation of root incomplete tooth and root complete tooth has been applied to few cases. The purpose of the present study was to clinically examine the possibility of tooth autotransplantation. Postoperative examination involved clinical symptoms such as tooth mobility and periodontal pocket and radiographic evidence such as ankylosis or lamina dura appearance. The results suggested that autotransplantation of tooth in oral functional rehabilitation was an appropriate treatment option for patients with missing teeth.
In modern composite resin restoration, material properties are important to give restorations natural colors and esthetics appearance. In recent years, based on the concept of minimal intervention (MI), light-cured composite resins have been frequently used to restore teeth without damaging healthy dentin with good esthetic results. However, it is very difficult to match colors in composite resin restorations. At present, a range of color shades is available for light-cured composite resins, but when restoring teeth with stained dentin, the color of composite resin selected using a shade guide does not always match the color of the surrounding dentin. This is because colors vary depending on composite resin thickness and dentine color. With regard to color compatibility of composite resins, both color and material translucency play important roles. In recent years, composite resins have been developed by taking into account the color and optical transparency of natural tooth enamel, and it is generally accepted that the appearance of translucent materials involves a complex relationship between various reflected lights. In other words, when mixing filler and matrix resin with a composite resin, light is diffused and reflected by surrounding dentin and colors. In the present study, composite resins with four different filler types, including a nano filler, were used in order to determine the effects of sample thickness, background color and filler morphology on color. The following conclusions were drawn: 1. When sample thickness was low, the spectral reflectivity of white and black backgrounds overlapped in the low wavelength region, and when sample thickness was high, spectral reflectivity was the same value in the high wavelength region. 2. Based on CIELAB, when thickness was low, hybrid composite resin with large filler and nano filler particles was less affected by L* value when compared when composite resin with small filler particles. 3. The contrast ratio of hybrid composite resin with large filler and nano filler particles was higher than that for composite resin with small filler particles when thickness was low. 4. For all samples, the greater the thickness, the lower the TP value and the smaller the rate of decrease in TP value.
The objective of this study was to examine the effect of specimen storage conditions on the dimensional change of light-cured restorative materials after curing. Ten commercially available conventional composite resins, six different products of flowable type composite resins and three different products of polyacid-modified composite resins were examined. The tapered cylindrical composite resin specimens were prepared using a stainless steel mold and the polymerization shrinkage of specimens after light curing was measured according to the method reported by Bowen et al. The specimens were weighed after determination of curing shrinkage. Then, the specimens were kept for 7 days in either air at 23±2℃ and 50±5% relative humidity or a moisture chamber at 37±2℃ and 95±5% relative humidity. The amounts of dimensional change and the weight of specimens were mensured again after storage of 7 days. In addition, the inorganic filler content in specimens was estimated by burning the specimens at 700℃ in a furnace. All the light-cured restorative materials shrank by light-curing. When the specimens were kept after curing in the moist condition, the amount of contraction was suppressed due to the absorption of water. A positive correlation was found after water sorption between the amounts of changes in weights and in dimensions of specimens. Changes in contraction of specimens after light-curing by water sorption appeared to be related to the nature of the matrix resin in composite resin.
Recently, bleaching treatment is requested not only for discolored teeth but also for healthy white teeth for esthetic reasons. Bleaching treatment is a minimal interventional treatment having the same concept as dental treatment without drilling. fore bleaching, and then LaserWhite10™ which includes carbamide peroxide was applied to all the teeth and activated with a semiconductor laser for bleaching. After bleaching. The color of the enamel surface of the specimens was measured and surface conditions were inspected by SEM. The bleaching procedure was done once (Group I), twice (Group II), and thrice (Group III). All measurements were compared among the three groups, and all SEM observations were inspected and the following results were obtained. 1. There were significant differences in color between pre-and post-treatment of teeth in Group I. The average color difference (ΔE) between the two was ΔE1=2.32±0.28. There were no obvious changes of enamel surfaces inspected by SEM. 2. The average color difference between the two was ΔE2=3.33±0.38 in Group II. The enelel surfaces were a little rough by SEM observation. 3. The average color difference between the two was ΔE3=3.53±0.41 in Group III. Enamel prism structures were found by SEM observation. A better bleaching effect was obtained with more times of bleaching, but the enamel surfaces became rougher. Therefore, the most effective bleaching procedure is once. The problem with carbamide peroxide that the bleaching effect became weak by increasing the number of bleaching times is improved. For clinical aspects, the bleaching procedureshould be performed no more than twice due to the surface condition of enamel, color alteration, and treatment time.
Alveolar bone is one of the most important target tissues for dental treatment by means of tissue engineering techniques. Bone metabolism is regulated by a variety of growth factors, including bone morphogenetic proteins and fibroblast growth factors, systemc hormones, such as parathyroid hormone, and locally produced cytokines. In addition to these fluid bone-regulating factors, mechanical forces on bone tissues also influence bone formation and bone resorption. However, the mechanism for the action of mechanical forces on bone remains to be studied. One such mechanical force is the carbon dioxide laser, which has been widely used in medical and dental treatment; and, low level laser treatment (LLLT) is of particular interest due to its stimulatory action in wound healing and tissue regeneration. In the present study, the effects of CO2 laser irradiation on bone formation in rat tibiae were histologically examined. The left tibia was irradiated daily at the midshaft for 15 min at a power of 1.0 W, and irradiation was continued for six days. Total energy density was 6.6 kj/cm2. At 7.14, and 21 days after irradiation was started, the tibiae were removed and subjected to histological and bone morphometric analysis. In the CO2 laser-irradiated groups, in the periosteum and endosteum, while soft X-ray analysis did not reveal and significant differences between the control and irradiated groups. Consistent with histological analysis, bone morphometric analysis showed that the rates of bone formation and bone mineral density were elevated in the irradiation groups. Alkaline phosphatase-positive osteoblasts lined the surface of the newly formed bone, and expression of type-I collagen and osteopontin was observed on the surface, with these proteins accumulating in the bone matrix. On the other hand, in nonirradiated groups, tartrate-resistant acid phosphatasepositive osteoclasts resided on the surface of cortical and trabecular bones. However, the number of osteoclasts was reduced by CO2 laser irradiation. Taken together, the present results indicate that the CO2 laser expands the mass of active osteoblasts in both periostium and endostium regions by stimulating the differentiation of osteogenic cells, and that it reduces the number of bone-resorbing osteoclasts, resulting in increased bone formation. These results may open the way for new applications of the CO2 laser in dental treatment.
The purpose of this study was to investigate the effect of polishing after the in-office bleaching method in terms of tooth color and roughness of the enamel surface. Shofu Hi-Lite™ (Shofu) was used as a bleaching agent, and Pressage (Shofu), a tooth-polishing paste, was used as a polishing agent. They were applied on bovine enamel. A handysurf E-30A (Tokyo Seimitsu) was used for measurements of the roughness of the enamel surface (Ra) after each treatment. The tooth color was measured with a spectral color-difference meter for micro-surface and evaluated with the CIE L*a*b* color system. Eighteen bovine crowns were assigned to three groups. The HP group underwent polishing after the bleaching treament; the H group underwent only bleaching; the P group underwent only polishing. Among these groups, roughness in the HP group increased significantly compared with the P group. The values ΔE*ab(ΔE*ab=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2), ΔL* and Δa* in the inter-group comparison increased significantly in the HP group and the H group compared with the P group. Δb* in the HP and H groups decreased significantly compared with the P group. In the intra-group comparison, ΔL* increased significantly and Δb* decreased significantly in the HP and H groups after the treatment compared with their preoperative values. No significant difference was found in Δa* in all the groups. The present study suggests that when polishing was conducted after bleaching, the surface became rougher than with only polishing or only bleaching. In the bleaching treatment group, ΔE*ab increased significantly. This was because the L* value increased and the b* value decreased significantly. No significant changes in color were found in the comparison between the group with only bleaching and the group with polishing after bleaching. The present study concluded that when the polishing was conducted after bleaching, the enamel surface became rougher, but tooth polishing after bleaching did not affect color.
Bleaching treatment has been becoming more popular for discolored teeth, as it does not require any cutting of enamel and dentine. However, the problem of color relapse after bleaching treatment remains unsolved. One of its causes is the rough enamel surface that is caused by chemical agents for bleaching. Thus, coating of the rough enamel surface with appropriate materials after bleaching treatment may be effective in preventing color relapse. In this study, seeking to protect the surface of bleached teeth, several properties of two types of experimental materials as enamel protectors, were examined as follows: 1. Evaluation of application methods: three kinds of application methods were compared. 2. Evaluation of discoloration: color changes after using strong staining solutions (coffee and artificial saliva) were measured. 3. Resistance to abrasing was evaluated following brushing with an electric toothbrush. 4. Observation of coated surfaces after thermal cycling. According to the results of color measurements and SEM observations, the following conclusions were obtained: 1. The best application method of the enamel protector on the teeth surface was a brush-on technique with sonic vibration. 2. Discoloration of the bleached tooth surface was reduced by using an enamel protector. 3. Double-layer application of enamel protectors gave better results in the abrasion test. 4. There was no difference between single- and double-layer applications in the thermal cycling test. There results suggest that the two kinds of enamel protector, applied with the double-layer methods, could reduce the color relapse of bleached teeth.
Purpose We have reported the efficacy of Nd:YAG laser irradiation for pain control in dental or periodontal treatments. However, there are few reports on the fundamental mechanisms of the effect of this laser on the sensory nervous systems. In this study, we investigated some factors which influenced the suppressive effect on the conduction of action potentials, in order to obtain data for producing a guide book for Nd:YAG laser irradiation in dental clinical treatment. Materials and Methods African clawed frog (Xenopus laevis) was immobilized with ice water and the spinal cord was destroyed. Dorsal surface skin together with three pairs of tactile nerve fine bundles (6 fine bundles in total) was removed, and cut into three pieces each with two tactile nerve bundles. Each piece of skin was put on filter paper soaked with physiological buffer solution, and was fixed on a rubber mat with metal pins. Chinese ink was painted on the dissected fine nerve bundle. Tactile stimulus was given with a single fiber of hemp palm at a tactile pressure 1-2 gf. Under audio visual monitoring, action potentials to the tactile stimulus were recorded by a silver electrode, and counted by a spike counter. Finally, rates of the action potential responses were recorded by a pen recorder. After Nd:YAG laser irradiation with various durations or pulse energies, tactile responses were periodically recorded, taking care to stimulate the same surface area under a dissection microscope. Results The suppression of action potentials depended upon the total energy rether than the pulse energy of the laser irradiation. The suppression was irreversible when the laser irradiation exceeded a certain total energy. Reversible suppression of action poten tials was obtained with sweeping mode irradiation, but it was very difficult to get this effect with fixed mode irradiation. This result endorses the propriety of the recommendation of the sweeping mode irradiation in dental treatment in our department. We think that these results would be useful for making a guideline for Nd:YAG laser irradiation in dental clinical treatment.
It is accepted that statins widely used as cholesterol-lowering drugs induce bone formation or expression of BMP-2 on several osteogenic cells. Since the statins may induce dentin regeneration on dental treatment, the effects of simvastatin, which is one type of statins, on the induction of odontoblastic differentiation in human dental pulp cells (HDPC) were examined. Alkaline phosphatase (ALP) activity as an index of odontoblastic differentiation in HDPC was measured after the application of simvastatin. and the gene expressions of growth factors (BMP-2 and TGF-β1) were analyzed by the method of luciferase reporter gene assay and RT-PCR. The expressions of specific dentin proteins were also analyzed by RT-PCR. When the HDPC was cultured with adding the simvastatin, the ALP activity of HDPC was decreased according to the simvastatin dose. When both TGF-β1 and BMP-2 were applied together, they decreased multiplicatively the ALP activity similar to the application of simvastatin, although TGF-β1 increased the ALP activity of HDPC whereas BMP-2 reduced the activity. The increases of TGF-β1 and BMP-2 and their mRNAs in HDPC culture with adding simvastatin were detected by luciferase reporter gene assay and RT-PCR, respectively. Since simvastatin inhibits choresterol synthesis via the inhibition of mevalonic acid synthesis, the effect of adding mevalonic acid in HDPC culture with simvastatin was examined. The result showed that it reduced the expression of both TGF-β1 and BMP-2. This indicates that the inhibition of mevalonic acid synthesis by simvastatin enhances the expression of TGF-β1 and BMP-2 of HDPC. In long-term culture of HPDC with adding simvastatin, the expression of dentin sialophosphoprotein (DSPP) was increased by the detection of RT-PCR. The result shows that simvastatin enhances the promotion of odontoblastic differentiation of HPDC. These results indicate that simvastatin enhances the expression of TGF-β1 and BMP-2 and promotes odontoblastic differentiation of HPDC. Simvastatin may thus be useful for dentin regeneration on tooth treatment of dental pulp disease.
Platelet-rich plasma (PRP) is an autologous source of platelet-derived growth factors, and has been used successfully in oral surgery repair. However, little is known about the underlying release mechanisms for these factors or the manner in which stimulation of human dental pulp cells is regulated. The present study investigated the efficacy of PRP as a stimulator of human dental pulp cell proliferation. Cell proliferation was weakly stimulated by treatment with PRP, while washed platelet (WPLT) treatment was more effective in stimulating cell growth. Moreover, platelet-poor plasma (PPP) dose-dependently inhibited the growth of cultured human dental pulp cells. Indomethacin and dexamethazone, a selective inhibitor of prostaglandins, markedly inhibited the WPLT-induced cell proliferation. In addition, SB431542, a specific inhibitor of TGF-β1 and TGF-β1, completely inhibited WPLT-induced PGE2 production and cell proliferation of the cells. WPLT rapidly induced COX-2 expression and PGE2 production, which in turn stimulated cell proliferation. These results suggest that WPLTs are potent stimulators of human dental pulp cells, and that the local release of the TGF-β-induced PGE2 is involved in WPLT-induced cell proliferation.
Recently, some manufacturers have developed new resin adhesive systems in which the conditioning, priming, and bonding procedures are set into one step. In those systems, clinical manipulations and procedures are so improved and simplified that clinicians are allowed to use them, and they do so more effectively. However, it is important to understand the effect of each treatment, especially adhesive application duration and air-blowing, since these can be the technique-sensitive factors of one-step adhesive systems. The purposes of this study were: 1) to compare the bond strength of seven kinds of one-step adhesive systems using microtensile bond testing and dye penetration testing, and 2) to investigate the influence of the adhesive application duration and airblowing variables on dentin bond strength of onestep odhesive systems: S3 Bond and G-Bond. 1) Freshly extracted human molars were used in this study. The dentin surfaces were created using abrasive paper. S3 Bond (Kuraray), G-Bond (GC), Adper™Pronpt™L-pop™(3M), Absolute (Dentsply Sankin), One-up Bond F Plus (Tokuyama Dental), AQ Bond Plus (Sun Medical), and iBond (Heraeus Kulzer) were used in this study. According to each manufacturer's instruction, adhesives were applied to prepared dentin surfaces, and then composite resins were placed onto each bonded experiment surface. After 24h, microtensile bond testing was performed in a bonded area of 1.0 × 1.0 mm at a crosshead speed of 0.5 mm/min. Cylinder-shaped cavities were prepared on the enamel surfaces of extracted human molars. These specimens were treated according to each manufacturer's instruction, and composite resins were condensed and then lightactivated. Bonded specimens were subjected to thermal cycling between 5-60℃ for 1,000 repetitions. 2) Freshly extracted human molars were used, and S3 Bond and G-Bond were employed in this study. The prepared dentin surfaces were treated according to each manufacturer's instructions and with various adhesive application durations (long or short) and air-blowing (gentle or hard). Microtensile bond tests were performed, and SEM observation was also performed to examine each of the resin-dentin interfaces. The results were as follows: 1) all of the seven kinds of one-step adhesive systems demonstrated good bonding performances, and there were no significant differences between the thickness of the resin bonding layer and the microtensile bond strength; 2) the dentin bond strength of S3 Bond and G-Bond decreased with various adhesive application durations and air-blowing. This tendency was more pronounced with G-Bond.
The prevalences of osteoporosis and periodontitis are very high in long-term facilities, so the quality of life becomes lower. The air of this study was to evaluate the effects of alendronate for the periodontium of elderly people in long-term homes. The subjects were 21 elderly people who lived in nursing homes. They were split into two groups: the drug-taking group (test group of 12 subjects) and the non-drug-taking group (control group of nine subjects). We had them take 'Fosamac' (5 mg) in the morning once a day for 21 months. The tooth of study was the voluntary canine. However, if this tooth was missing, another tooth was selected for research. Clinical periodontal parameters (GI, gingival index; PlI, plaque index; PD, pocket depth; LA, loss of attachment; BOP, bleeding on probing), bone mineral density (the methods of CXD: computed X-ray densitometry; DXA: dual X-ray absorptiometry; and QUS: quantitative ultrasound), and NTx (crosslinked N-telopeptides of type I collagen) were examined at baseline and at 7, 14, and 21 months after the beginning of the drug consumption. In addition, dental X-ray photographs to examine BL (bone loss) were taken during the same periods. Significant decreases in NTx were found between the baseline and 7 and 14 months in the test group, and the difference between baseline and 21 months in the test group increased. PD tended to improve in the test group, but it did not change significantly in the control group. BL did not change during the research periods in the test group, although it tended to increase in the control group. In contrast, differences of other clinical periodontal parameters during the study period were not found between the two groups including the bone mineral density (CXD, DXA, and QUS). These results suggest that alendronate possibly prevents periodontitis from becoming worse, although it does not improve the periodontium in the nursing home patients.
Bleaching does not require tooth grinding, and it has become the preferred initial choice for patients who want to improve the color of their teeth. Although there are clinical reports on bleaching, few have evaluated the bleached enamel surface properties. The purpose of this study was to examine the effrece of 35% hydrogen peroxide on the surface properties of extracted bovine enamel. The bleaching agent used was the Shofu Hi-Lite® bleaching system. We investigated the change in the surface micro-hardness (Vicker's hardness) and nanohardness (Universal hardness) in enamel surface before and after exposure in vitro to the bleaching agent. Creck resistance indirectly related to the fracture toughness was also measured. A Vicker's hardness indenter was used to initiate crackes into bleached enamel surface. In addition the microstructure and compositional changes (Ca, P) of the bleached enamel surface and its cross section were assessed using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). A laser fluorescence diagnostic device (DIAGNOdent™) was also used to detect degenerate organic substance in the bleaching enamel surface. This investigation revealed no significant differences in micro and nanohardness values and fracture touthness values among the surface of bleached enamel treated three and 18 times. Following Vicker's micro-hardness indentation on the bleaching enamel, significant cracking fracture and deformation pattern were not observed. However, results of the bleached enamel in a cross section at 0-50 μm depth showed a statistically significant (p<0.05) decrease in micro and nano-hardness compared with the control. The analysis of the SEM, EPMA, and DIAGnodent™ measurement showed differences in surface topography and composition and peak value for enamel treated with the bleaching agent. Surface destruction was seen; however, it was not as severe as that seen in the control. The bleaching caused a decrease of Ca and P at 0-50 μm depth compared with the polished surface.
Many types of light-curing units have been marketed in recent years. Light sources for use instead of the halogen lamp (HL) have been developed and used in the dental field, such as the xenon lamp (XL) and the blue Light Emitting Diode (LED). However, little is known about the influence of the polymerization and the adhesion of the newly developed fluoride-releasing one-step bonding systems to teeth by using different types of curing units. The purpose of this study was to investigate the tensile bond strength and nanohardness of a fluoride-releasing one-step resin bonding system cured by three types of light curing units. An LED curing unit (DC®] BlueLex, Yoshida), a conventional HL curing unit (Coltlux4, Coltene), and an XL curing unit (Apollo™ 95E, DMD) were tested. The light intensities of the light-curing units were measured. Two resin restorative systems: One-Up Bond F Plus/Palfique Estelite Σ(shade A3, Tokuyama Dental) and Fluoro Bond Shake One/Beautifil (shade A3, Shofu), were used. Bovine freshly extracted incisors were mounted in self-curing resin facial surfaces and were ground with 800 grit SiC paper. The enamel and dentin surfaces were tested according to each manufacturer's instructions, and the composite resins were condensed into a Teflon mold (1 mm height, 3 mm internal diameter). The adhesives were cured with the HL for 10 seconds, the XL for 6 seconds, and the LED for 10 seconds, respectively. The composite resins were cured with the HL for 40 seconds, the XL for 6 seconds, and the LED for 20 seconds. The specimens were stored in distilled water at 37℃ for 24 hours, and then the enamel and the dentin bond strength were tested in a tensile mode using universal testing machine at a cross-head speed of 1.0 mm/min (n=10). Selective SEM examinations were made on the interfaces of debonded specimens. Nano hardness of the resin adhesives was also measured using a nano-indentation tester (MZT-522) with 20 mN load. Means and standard deviation were calculated for all tests. One-way Anova and Scheffe's test (post-hoc test) were performed to compare the results of each material (p<0.05). As results, the tensile bond strength of Fluoro Bond Shake One/Beautifil was about 8.5-14.9 MPa to the enamel, and about 8.7-12.8 MPa to the dentin, which was not significantly different from One-Up Bond F Plus/Palfique Estelite Σ (enamel:8.3-20.6 MPa, dentin: 9.4-14.6 MPa). The tensile bond strength of Fluoro Bond Shake One/Beautifil with the XL curing was higher than the strengths obtained with the HL and the LED curing. The tensile bond strength of One-Up Bond F Plus/Palfique Estelite Σ with the XL curing was lower than the strengths obtained with the HL and the LED curing. However, there was no statistically significan difference in average tensile bond strength among the three light-curing units. The SEM images of debonded surfaces showed a higher number of cohesive failures in enamel and dentin for specimens. The most common failure pattern was mixed type (cohesive and adhesive failure). Nano-hardness in One-Up Bond F Plus cured with the XL was significantly lower than the hardness cured with the HL and the LED, however; the hardness in Fluoro Bond Shake One cured with the XL was significantly higher than that cured with the HL and the LED. The light intensity for the HL, the XL, and the LED was regulated in the range from 150-300 mW/cm^2, 1,200-1,350 mW/cm2 and 900-1,050 mW/cm2 by measuring the Light Checker (3M), respectively. These results suggested that compatibility between catalytic system and light sources was to be considered as well as energy of light-curing units in resin adhesives.