• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.155-172
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• 1989

The purpose of this study is to measure the bonding strength at the enamel and dentin of extracted bovine incisors when they are irradiated by W Nd: YAG, EoQ Nd: YAG, and CW $CO_2$ laser, etched and then attached by composite resin. The laser-irradiated surface, the etched surface after the laser-irradiation and the interface of the treated surface and resin are observed by using scanning electron microscope. The NP Nd:YAG laser is used at the peam power of 207 KW. The EOQ Nd: YAG laser is used at the peak power of 1.15Mk. The CW $CO_2$ laser is used at the energy output of 5W and 10W in enamel; in dentin, at the energy output of 2W. The obtained results were as follows: 1. The shear bond strength of enamel decreased in the following order: EOQ Nd:YAG laser group, NP Nd:YAG laser group, CW $CO_2$ laser groups, unlased group. The unlased group showed a significant difference from EOQ Nd:YAG laser group (P<0.01), NP Nd:YAG laser group (P<0.05), but no significant difference from CW $CO_2$ laser group (P>0.05). 2. The shear bond strength of dentin decreased in the following order: CW $CO_2$ laser group, NP Nd:YAG laser group, unlased group, EOQ Nd:YAG laser group. The unlased group showed a significant difference from CW $CO_2$ laser group (P<0.01), but no significant difference from Nd:YAG laser groups (P>0.05). 3. The scanning electron microscope of enamel revealed irregular microcrack and pore at the surface in the NP Nd:YAG laser group and CW $CO_2$ laser group, but the crackless flat surface in the EOQ Nd:YAG laser group. 4. The scanning electron microscope of dentin revealed obstruction of in most of dentinal tubule and decrease of diameter. 5. The scanning electron microscope of the interface of resin and enamel revealed prominent penetration of resin tag in the EOQ Nd:YAG laser group.

• Journal of Korean Academy of Oral Health
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• v.42 no.4
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• pp.118-123
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• 2018

Objective: This study aimed to investigate the effects of fluoride-containing acidic tea beverages on bovine teeth surfaces. Methods: The pH values and fluoride concentrations of 11 kinds of mineral water and 23 kinds of tea were measured. The fluoride-containing Seopyenje black tea beverages with pH 3.48 were chosen for the experimental group. Distilled water that did not contain fluoride and had the same pH value as that of the Seopyenje black teas served as the positive control. The Jeju Samdasoo mineral waters with neural pH (pH 7.52) and no fluoride were chosen as the negative control. Bovine teeth in each group were submerged for 10 minutes. Thereafter, surface microhardness of each bovine teeth was measured and the results were analyzed. Results: The pH value range was 6.94-8.09 ($mean=7.37{\pm}0.08$) for the 11 kinds of mineral water and 3.48-6.74 ($5.62{\pm}0.05$) for the 23 tea beverages. Titratable acidity of the Seopyenje black tea beverages was higher than that of the distilled water mixed with citric acid, and the pH was 5.5 and 7.0, respectively. The fluoride content of the 11 kinds of mineral water was 0-1.09 ppm ($mean=0.44{\pm}0.02ppm$) that of the 23 tea beverages was and 0-0.74 ppm ($0.64{\pm}0.06ppm$). In terms of enamel microhardness reduction of the bovine teeth, the tea beverages had the largest effects. There was no significant difference in microhardness reduction between the tea beverages and distilled water mixed with citric acid (P>0.05). Conversely, a significant difference was found between the kinds of mineral water and tea beverages, and also between mineral water and distilled water mixed with citric acid (P<0.05). Conclusions: Acidic tea beverages appeared to erode the surfaces of bovine teeth. The amount of fluoride in the tea beverages was not enough to inhibit erosion. Therefore, frequent intakes of acidic tea beverage are likely to increase erosion on the surfaces of bovine teeth, by affecting the enamel microhardness of teeth.

• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.393-410
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• 2004

The purpose of this study was to investigate effect of enamel matrix derivative on guided bone regeneration with intramarrow penetration in rabbits. Eight adult male rabbits (mean BW 2Kg) were used in this study. Intramarrow penetration defects were surgically created with round carbide bur(HP long #6) on calvaria of rabbits. Defects were assigned to the control group grafted with mixture of the same quantity of demineralized freeze-dried bone allograft and deproteinized bovine bone mineral. Then, guided bone regeneration was carried out using resorbable membrane and suture. Enamel matrix derivative applied to defects was assigned to the test group. And treated as same manners as the control group. At 1, 2, 3 and 8 weeks after the surgery, animals were sacrificed, specimens were obtained and stained with Hematoxylin-Eosin for light microscopic evaluation. The results of this study were as follows : 1. At 1, 2 and 3 weeks, no differences were observed between the control group and the test group in the aspect of bone formation around bone graft. 2. Proliferation of blood capillary was faster in the test group than in the control group. 3. Bone regeneration in intramarrow penetration was faster in the test group than in the control group. 4. At 8 weeks, new osteoid tissue formation around bone graft was more prominent in the test group than in the control group. From the above results, enamel matrix derivative might be considered as the osteopromotion material and effective in the guided bone regeneration with intramarrow penetration.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.387-394
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• 1993

In order to investigate the effects of continuous and pH cyclic remineralization, artificial enamel carious lesions were produced on sections of about 2mm thickness of bovine incisor. 0.1M lactic acid solution adjusted to a pH of 4.3 and saturity of $2.98{\times}10^{-8}$ was used as demineralizing solution. The lesions were remineralized with the solution of pH 7.0 containing 1.5mM $CaCl_2$, 0.9 mM $KH_2PO_4$ and 20mM Hepes. In continuous remineralization procedure, the specimens were immersed in remineralizing solution continuously for 72 hours. In pH cyclic remineralization procedure, the sections were immersed in remineralizing solution for 6 hours and in dermineralizing solution for 20 minutes alternately during 72 hours. The effect of remineralization was determined by polarizing microscopy and electron microprobe analysis. The obtained results were as follows. 1. In case of continuous remineralization, the lesion depth was reduced partially or unchanged. 2. In pH cyclic condition, the thichness of surface layer and the lesion depth were increased simultaneously. 3. The mineral content of lesion was recovered to the level of sound enamel by remineraiization.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.3
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• pp.640-658
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• 1996

The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

• The korean journal of orthodontics
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• v.52 no.1
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• pp.75-79
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• 2022

Objective: To investigate remineralizing effect of three fluoride regimens on artificially demineralized enamel around orthodontic bracket by analyzing mineral density (MD) acquired from micro-computed tomography (micro-CT). Methods: Forty-eight bracket bonded bovine incisors were prepared to create demineralized enamel (DE) surface. The samples were divided into four groups according to the fluoride regimen: 1) no fluoridation, 2) 1.23% acidulated phosphate fluoride (APF) gel, 3) fluoridated toothpaste, and 4) 0.05% sodium fluoride mouthwash. Micro-CT was scanned after demineralization (T0), and 2 weeks (T1) and 4 weeks (T2) of fluoridation. Results: APF gel showed highest remineralization of DE during T1-T0 interval among the groups (p < 0.05); followed by toothpaste, mouthwash and no fluoridation. APF gel and toothpaste demonstrated significant increase in MD after 4 weeks of application (p < 0.05). Conclusions: Remineralization effects of three fluoride regimens were depicted through micro-CT analysis, of which APF gel was most effective.

• The korean journal of orthodontics
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• v.35 no.1 s.108
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• pp.43-50
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• 2005

The purpose of this study was to evaluate the effects of a sealant resin on enamel demineralization In orthodontic bracket bonding. The forty eight extracted sound bovine teeth were subdivided into four groups and treated with Phase II (Reliance, itasca. III) on the surface Group 1 was not treated. Group 2 was acid etched with 37% phosphoric acid for 30 seconds. Group 3 was applied with sealant after acid etching. Group 4 was applied with resin paste after acid etching and sealant application. Each group was demineralized in artificial caries solution. Demineralized enamel depth was measured by confocal laser scanning microscopy. The results were as follows: the mean demineralized enamel depth was $47.4{\mu}m$. (Group 1), $61.8{\mu}m$ (Group 2), $13.9{\mu}m$ (Group 3). $8.2{\mu}m$ (Group 4) the demineralized enamel depth was increased in Group 2 than in Group 1 (p<0.05); the demineralized enamel depth was reduced in Group 3 than in Group 1 and Group 2 with statistically significant differences (p<0.05): and demineralization in Group 4 was very little. The results of the present study indicate that sealant application is useful for reducing enamel demineralization in orthodontic bracket bonding.

• The korean journal of orthodontics
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• v.48 no.4
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• pp.245-252
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• 2018

Objective: We aimed to perform in-vitro evaluation to compare 1) shear bond strength (SBS), adhesive remnant index (ARI), and color change between self-etched and acid-etched primers; 2) the SBS, ARI and color change between direct and indirect bonding; and 3) the enamel roughness (ER) between 12-blade bur and aluminum oxide polisher debonding methods. Methods: Seventy bovine incisors were distributed in seven groups: control (no bonding), direct (DTBX), and 5 indirect bonding (ITBX, IZ350, ISONDHI, ISEP, and ITBXp). Transbond XT Primer was used in the DTBX, ITBX, and ITBXp groups, flow resin Z350 in the IZ350 group, Sondhi in the ISONDHI group, and SEP primer in the ISEP group. SBS, ARI, and ER were evaluated. The adhesive remnant was removed using a low-speed tungsten bur in all groups except the ITBXp, in which an aluminum oxide polisher was used. After coffee staining, color evaluations were performed using a spectrophotometer immediately after staining and prior to bonding. Results: ISONDHI and ISEP showed significantly lower SBS (p < 0.01). DTBX had a greater number of teeth with all the adhesive on the enamel (70%), compared with the indirect bonding groups (0-30%). The ER in the ITBX and ITBXp groups was found to be greater because of both clean-up techniques used. Conclusions: Direct and indirect bonding have similar results and all the primers used show satisfactory adhesion strength. Use of burs and polishers increases the ER, but polishers ensure greater integrity of the initial roughness. Resin tags do not change the color of the teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.96-104
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• 2001

This study was performed to compare the abrasiveness and wear resistance of several restorative materials occluding enamel and gold alloy. Intact labial surface of bovine incisor and the plain portion of type III gold alloy were used as plate specimens, and pin specimens were fabricated using $Artglass^{(R)},\;Targis^{(R)},\;Sculpture^{(R)}$. After two-body wear test using pin and plate model, amount of vertical height loss of plate and pin specimens were measured and statically analyzed. The amount of vertical height loss of plate specimens against pin specimens were measured by a roughness measurement instrument. The amount of vertical height loss of pin specimens against plate specimens were measured by an image analyzing program after taking scanning electron micrographs of pin specimens. The results were as following. 1. As fir the amount of enamel wear. gold group showed least amount of wear. There was no significant difference among Sculpture, Targis and Artglass groups(p<0.05). 2. As for the amount of gold wear Sculpture group standed first and Targis and Artglass group followed respectively, and there was significant difference between Sculpture and Artglass groups(p<0.05). 3. As for the amount of restorative materials against enamel, Artglass group showed greatest, and there was no significant difference among gold. Sculpture, Targis groups(p<0.05). 4. As for the amount of restorative materials against gold, Artglass group standed first and Targis and Sculpture group followed respectively, and there was significant difference among each groups(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.2
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• pp.489-501
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• 1996

This study was to evaluate shear bond strength of fluoride-releasing sealant and nonfluoride releasing sealant to enamel surface of bovine tooth. 80 extracted bovine teeth were randomly assigned to four groups, and four kinds of sealants including Teethmate-A(Kuraray Co.), Teethmate-F(Kuraray Co.), Helioseal(Vivadent Co.), Helioseal-F(Vivadent Co.) were bonded to exposed enamel surfaces using silicon plate. Shear bond strength was determined in an instron universal testing machine at a crosshead speed of 1mm/min. Then, the fracture surfaces of test specimens were investigated with scanning electron microscope. The obtained results were as follows; 1. The shear bond strength decreased in the following order : Teethmate-A(18.31MPa), Teethmate-F(11.90MPa), Helioseal (11.74 MPa), Helioseal-F(10.64MPa). 2. The shear bond strength of Teethmate-A showed significantly higher than that of Teethmate-F(P<0.05), but Helioseal and Helioseal-F didn't showed statistically different(P<0.05). 3. According to the SEM, Teethmate-A group showed cohesive failure, and Teethmate-A group & Helioseal group showed mixed pattern of cohesive and adhesive failure and Helioseal-F group showed adhesive failure.