• International Journal of Oral Biology
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• v.40 no.1
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• pp.1-9
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• 2015

Osteocalcin (OC) is the most abundant noncollagenous protein of extracellular matrix in the bone. In an OC deficient mouse, bone formation rates are increased in cancellous and cortical bones. OC is known as a negative regulator of mineral apposition. OC is also expressed in the tooth of the rat, bovine, and human. However, little is known about OC during tooth development in Xenopus. The purpose of this study is to compare the expression of OC with mineralization in the developing tooth of Xenopus, by using von Kossa staining and in situ hybridization. At stage 56, the developmental stage of tooth germ corresponds to the cap stage, and an acellular zone was apparent between the dental papilla and the enamel organ. From stage 57, calcium deposition was revealed by von Kossa staining prior to OC expression, and the differentiated odontoblasts forming predentin were located at adjoining predentin. At stage 58, OC transcripts were detected in the differentiated odontoblasts. At stage 66, OC mRNA was expressed in the odontoblasts, which was aligned in a single layer at the periphery of the pulp. These findings suggest that OC may play a role in mineralization and odontogenesis of tooth development in Xenopus.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.413-422
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• 1993

The purpose of this study was to evaluate the adaptation of light cured glass ionomer cement and composite resin using all- etch technique to tooth structure. In this study, class V cavities were prepared on the buccal surfaces of 10 extracted human premolar teeth with cementum margin and teeth were randomly assigned 2 groups of 5 teeth each. The cavities of glass ionomer cement group were filled with the light cured glass ionomer cement(Fuji II LC) and the cavities of composite resin group were filled with the light cured composite resion(P - 50) using all- etch technique with All- Bond 2. The restored teeth were stored in 100 % relative humidity at $37^{\circ}C$ for 48 hours. And then, the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of restorations. Adaptation at tooth - restoration interface were assessed occlusally, gingivally, and axially by scanning electron microscope. The results were as follows : 1. The adaptation to enamel walls of composite resin restorations using All - Bond 2 showed better than glass ionomer restorations. 2. The adaptation to gingival and axial walls of glass ionomer restorations showed better than composite resin restorations using All - Bond 2. 3. In both groups, occlusal margins of restorations showed better adaptation than gingival margins of restorations.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.168-176
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• 2013

In this study, hydroxyapatite (HAp) was incorporated into toothpaste and its effect on the remineralization and restoration of dental enamel was evaluated. Different sets of toothpaste were incorporated with HAp levels of 0%, 5%, 10 %, and 15 %. The filler particles of the resulting toothpaste samples were observed via SEM and XRD and compared with compositions of several commercially available toothpastes, showing that the HAp was successfully incorporated into the toothpaste samples. Different sets of human enamel were inflicted with lesions and then treated with the different fabricated toothpaste samples for five minutes three times a day for seven days. During the treatment, the teeth were subjected to demineralization and remineralization cycles to simulate the effect of natural saliva. The surface of the enamel samples were observed using SEM before and after one week of treatment, showing the formation of HAp layers on the surfaces of the enamel samples. The effect of the toothpaste on the lesions was observed using an inverted light microscope and the lesion depth was found to decrease as the concentration of HAp in the toothpaste used increased. HAp was successfully incorporated in the toothpaste and its presence was found to lessen lesion depths and improve tooth remineralization.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.240-250
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• 1999

The purpose of this study was to evaluate the effect of different etching time on the shear bond strength and adaptibility of composite to enamel and dentin when used one-bottle adhesive Prime & Bond$^{TM}$ 2.0. The proximal and occlusal surfaces of 88 extracted human molars were ground to expose enamel(n=44) and dentin (=44) using diamond wheel saw. Teeth were randomly assigned to four test groups(n=11) and received the following treatments : Control group were conditioned with 36% phosphoric acid for 20 sec. according to the manufacturer's directions. Experimental 10 sec. group, 30 sec. group and 60 sec. group were conditioned with 36% phosphoric acid for 10 sec., 30 sec. and 60 sec., respectively. Teeth were rinsed and dried for 2 sec. Prime & Bond$^{TM}$ 2.0 were applied according to the manufacturer's directions and Spectrum$^{TM}$ TPH composite resins were bonded to enamel and dentin surfaces. All specimens were stored in distilled water for 24 hours. Eighty specimens were sheared in a Universal Testing Machine with a crosshead speed of 5mm/minute. One way ANOVA and LSD test were used for statistical analysis of the data. Failure modes of all specimens after shear bond strength test were examined and listed. Also, representive postfracture modes and eight specimens were examined under scanning electron microscope. The results of this study were as follows: 1. The shear bond strength to enamel was the highest value in 30 sec. group (20.68${\pm}$8.54MPa) and the lowest value in 10 sec. group (14.92${\pm}$6.07MPa), so there was significant difference of shear bond strength between two groups (p<0.05). But there was no significant difference among other groups (p>0.05). With longer etching time to enamel from 10 sec. to 30 sec., higher the shear bond strength was obtained, but the shear bond strength was decreased at 60 sec. etching time. 2. The shear bond strength to dentin was the highest value in control group (13.08${\pm}$6.25MPa) and the lowest value in 60 sec. group (9.47${\pm}$3.35MPa), but there was no significant difference among the all groups (p>0.05). The eching time over 20 sec. decreased the shear bond strength to dentin. 3. In SEM observation, the enamel and resin interfaces were showed close adaptation with no relation to etching time of enamel. And the dentin and resin interfaces were showed close adaptation at 20 sec. and 30 sec. etching time, but showed some gaps at 10 sec. and 60 sec. etching time. Accordingly, these results indicated that a appropriate etching time in Prime & Bond$^{TM}$ 2.0 was required to be 30 sec. in enamel and 20 sec. in dentin for the high shear bond strength and good adaptation between the composite resin and tooth substance.

• Restorative Dentistry and Endodontics
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• v.31 no.6
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• pp.445-451
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• 2006

The purposes of this study were to compare the effects of one or two applications of all-in-one adhesives on microtensile bond strengths (${\mu}$TBS) to unground enamel and to investigate the morphological changes in enamel surfaces treated with these adhesives using a scanning electron microscopy (SEM). Twenty-five noncarious, unrestored human mandibular molars were used. The unground enamel surfaces were cleansed with pumice. The following adhesives were applied to lingual, mid-coronal surfaces according to manufacture's directions; Clearfil SE bond in SE group, Adper Prompt L-Pop$^{TM}$1 coat in LP1 group, 2 coats in LP2 group, Xeno$^{\R}$III1 coat in XN1 group, and 2 coats in XN2 group. After application of the adhesives, a hybrid light-activated resin composite was built up on the unground enamel. Each tooth was sectioned to make a cross-sectional area of approximately 1.0 mm$^2$ for each stick. The microtensile bond strength was determined. Each specimen was observed under SEM to examine the morphological changes. Data were analyzed with one-way ANOVA. The results of this study were as follows; 1. The microtensile bond strength values were; SE (19.77 ${\pm}$ 2.44 MPa), LP1 (13.88 ${\pm}$ 3.67 MPa), LP2 (14.50 ${\pm}$ 2.52 MPa), XN1 (14.42 ${\pm}$ 2.51 MPa) and XN2 (15.28 ${\pm}$ 2.79 MPa). SE was significantly higher than the other groups in bond strength (p < 0.05). All groups except SE were not significantly different in bond strength (p < 0.05). 2. All groups were characterized as shallow and irregular etching patterns.

• Current Optics and Photonics
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• v.6 no.1
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• pp.86-91
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• 2022

Two-photon fluorescence microscopy was performed on the enamel-dentin junction area of a human tooth using a femtosecond pulsed laser. We obtained a clear image contrast between the bright dentin and dark tubules with the autofluorescence generated from the endogenous fluorophores in dentin. The autofluorescence shows a broad spectrum due to complex cross links between dentinal collagens, which extend from blue to orange wavelengths (470-590 nm), but a gradual autofluorescence loss in photobleaching was observed for a long-term exposure under strong excitation. For increasing excitation power, we found that two-step decay becomes significant in the spectrally integrated autofluorescence.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.427-433
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• 2013

The aim of this study was to evaluate the efficacy of bleached tooth with white toothpaste on the whitening effect, microhardness test. Forty-four human interior teeth were randomly assigned to two groups as follows: Group 1 was used general toothpaste as control, Group 2 exposed to white toothpaste at 3 times a day for 3 minutes. The total application time was 4 weeks. After each application, all tooth were washed with distilled water and immersed in artificial saliva. The color change and microhardness were measured using CIELab Color system and microhardness tester. The data were analyzed by student t-test, using SPSS 20.0 statistical computer program (SPSS Inc., USA). The overall color changes (${\Delta}E$) by white toothpaste have a capability of the whitening efficacy by factor of 2.3 times larger compared with general toothpaste. Moreover, the application of white toothpaste did not cause any microhardness reduction on enamel surface.

• Journal of dental hygiene science
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• v.10 no.4
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• pp.295-300
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• 2010

The aim of this study were to elucidate effects of fluoridated bleaching agents and post-treatment fluoride application on the color and microhardness of enamel surface. Twenty freshly extracted human adult molar were each sectioned into halves, the specimens divided and treated according to four experimental groups: 1, untreated controls: 2, treatment with 10% carbamide peroxide (CP) bleaching agent; 3, treatment with 10% CP containing 0.11% fluoride; 4, treatment with 10% CP followed by a 0.9% sodium fluoride gel application. Group 2-4 were compared with the baseline data. treated 8 h per day for 14 days then immersed in distilled water for 2 weeks. Changes in enamel color and microhardness were evaluated on Days 7 and 14. All the bleached enamel specimens revealed increased whiteness and overall color value. Groups 2 and 4 showed significantly decreased enamel microhardness compared to their baseline. The specimens treated with fluoridated bleaching agents showed relatively less reduction in enamel microhardness than those treated with nonfluoridated agents during the bleaching treatment. The addition of fluoride did not impede the tooth whitening. The fluoridated bleaching agents reduced the microhardness loss of enamel.

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.201-206
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• 2016

PURPOSE. The aim of this study was to compare the radiopacity of 6 modern resin cements with that of human enamel and dentine using the Digora digital radiography system, to verify whether they meet the requirements of ANSI/ADA specification no. 27/1993 and the ISO 4049/2000 standard and assess whether their radiopacity is influenced by the thickness of the cement employed. MATERIALS AND METHODS. Three 3-thickness samples (0.5, 1 and 1.5 mm) were fabricated for each material. The individual cement samples were radiographed on the CCD sensor next to the aluminium wedge and the tooth samples. Five radiographs were made of each sample and therefore five readings of radiographic density were taken for each thickness of the materials. The radiopacity was measured in pixels using Digora 2.6 software. The calibration curve obtained from the mean values of each step of the wedge made it possible to obtain the equivalent in mm of aluminium for each mm of the luting material. RESULTS. With the exception of Variolink Veneer Medium Value 0, all the cements studied were more radiopaque than enamel and dentin (P<.05) and complied with the ISO and ANSI/ADA requirements (P<.001). The radiopacity of all the cements examined depended on their thickness: the thicker the material, the greater its radiopacity. CONCLUSION. All materials except Variolink Veneer Medium Value 0 yielded radiopacity values that complied with the recommendations of the ISO and ANSI/ADA. Variolink Veneer Medium Value 0 showed less radiopacity than enamel and dentin.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.947-954
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• 1998

The purpose of this study was to compare shear bonding strengths and debonding patterns of the ceramic brackets attached on the crystal which were grown on the enamel surface of a tooth with different concentrations of lithium sulphate-contained polyacrylic acid in different application times. Four kinds of concentrations of mixed solutions were made and applied to the enamel surface on extracted human premolars. The solutions were made by adding 0.3M or 0.6M of lithium sulfate to $50\%\;or\;65\%$ of polyacrylic acid with 0.3M sulfuric acid. The solutions were applied for 30 or 60 seconds. After bonding, a universal testing machine was used to measure the shear bond strength, and then observations were made of debonding patterns through the stereoscope. And the enamel surface was observed through the scanning electron microscope to examine the pattern of crystal growth and debonding. The results were as follows: 1. Shear bond strength in the enamel surface treated with $50\%$ polyacrylic acid was higher than that with $65\%$ polyacrylic acid. 2. There were no statistical differences in shear bond strength according to concentration of lithium sulfate and application time of solutions . 3. Enamel surface was almost free of resin debris after debonding. 4. Enamel surface treated with $50\%$ polyacrylic acid showed higher density of crystal growth than that with $65\%$ polyacrylic acid under scanning electron microscope.