• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.17 no.1
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• pp.271-278
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• 1987

The purpose of the present study was to investigate associations between periapical and bitewing techniques by assessing the crestal alveolar bone. This article also reports the ability of these two techniques to correctly detect evidence of interproximal dental caries, and comparison between the interproximal overlapping of teeth. Bitewing and periapical radiographs were used from posterior quardants of 243 dental students in Seoul National University. The distance from cemento-enamel junction to the alveolar crest (CEJ-AC) was measured for each proximal surface from the distal of cuspid to the distal of second molar. Data were arranged according to the proximal surface examined, and bitewing and periapical measurements were compared using paired tests. The obtained results were as follows: 1. In maxilla, a significant t ratio with a P value of 0.05 or less reached for 100% and in mandible, reached for 94%. 2. The anatomic limitations imposed on periapical radiographic technique, most often result in somewhat foreshortened radiographic images. This situation would tend to be accentuated by the anatomical restrictions of the hard palate. 3. Consequently, since the significant differences frequently exist between measurements obtained from bitewing and periapical techniques, it is important to define which technique is used. 4. The number of the interproximal overlapping was the largest medial side of the maxillary second molar, while the smallest at the distal side of the mandibular second premolar. And the overall number of the interproximal overlapping was more (538) in the periapical technique than in the bitewing technique (372). 5. The interproximal dental carious lesions were detected more (74) on the bitewing films than on the periapical ones (23). The fact was resulted from the small number of interproximal overlapping and relative easi- ness of obtaining horizontal angulation in taking the bitewing radiographs.

• Applied Microscopy
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• v.41 no.4
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• pp.223-228
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• 2011

White light scanning interferometry has been employed to analyze surface features of diverse specimens. Long established in the field of materials engineering, the technique provides quantitative three-dimensional data as well as qualitative morphological images. It uses white light that is split and reflected from a reference mirror and an object. Merged together, the light generates interference patterns representing topographical contours of the object surface. The amplitude of the z-axis data is differentiated by gray scale. The technique allows the rapid, noncontact, and wide-field measurements for morphometry of biological specimens including chondrocytes, tooth enamel, and plant leaves. Quantification of the dimension of surface structures such as width, length, and elevation angle could be achievable by white light scanning interferometry. The light reflection from plant leaves has been assumed to be sufficient for the technique. Without special specimen preparations like conductive metal coating, the technique can be increasingly used for quantitative three-dimensional surface measurements of biological specimens.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.682-689
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• 1998

The purpose of this study was to evaluate the sealing ability of the Microseal$^{(R)}$, which was new obturation system made by Tycom company, U.S.A. Forty-five extracted single-rooted human teeth were resected at cemento-enamel junction and divided three groups. All canals were prepared using Profile system, and then each group was obturated by lateral condensation technique (group 1), vertical condensation technique (group 2) and Microseal$^{(R)}$ condensation technique (group 3) with root canal sealer. Teeth were immersed in resorcinol-formaldehyde resin for 5 days at $4^{\circ}C$ and the resin was allowed to polymerize completely for 4 days at room temperature. Teeth were resected horizontally at 1 mm (level I), 2 mm (level II), 3 mm (level III) from the anatomical root apex using low speed microtome and examined with Image analyzer (IBASR, Zeiss co., Germany.) at ${\times}25$ magnification. The gab between the canal wall and the filling material, which was filled with the resin, was measured at each of the three levels. Each ratio of leakage was expressed percentage by calculating the ratio of the area of the resin to the total area of the canal and was analyzed statistically (one-way ANOVA). The results were as follows; 1. The mean ratio of leakage (%) was 6.46% at group 1, 3.06% at group 2, 11.27% at group 3. 2. When evaluating the ratio of leakage at the three levels, there was level I> level II> level III in all groups. Especially, the difference between level I and level III was statistically significant (p<0.05). 3. When evaluating the ratio of leakage at the three groups, there was group 3> group 1> group 2 at all levels. Especially the difference between group 2 and group 3 was statistically significant (p<0.05).

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.83-91
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• 2004

This study was performed to examine treatment efficiency and patient discomfort rate according to used handpiece speed in clean-up technique. Brackets were bonded to extracted human premolar(50 teeth). After debonding, 50 extracted human premolar were divided Into each two groups(low speed handpiece group with tungsten carbide bur and high speed handpiece group with ultra-fine diamond finishing bur) of 25 according to used handpiece speed in clean-up technique. In clean-up procedure, teeth vibration and pulp thermal changes were measured. After clean-up procedure, the enamel surfaces of randomly selected 10 teeth from each two groups were taken by SEM and evaluated. The findings of this study were as follows ; 1. During resin removal, tooth vibrations of various amplitude in low speed handpiece group were more than those of high speed handpiece. 2. The pulpal thermal changes of high speed handpiece group were significantly higher than those of low speed handpiece group, also the resin removal time in high speed handpiece group was almost as twice as in low speed handpiece group. 3. The figures of SEM to enamel surfaces after resin removal showed that notches and resin remnants in high speed handpiece group were more than those in low speed handpiece group.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.218-224
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• 2010

The prevalence of developmental defects of enamel and lesios by post-orthodontic decalcification has been reported with increasing frequency. Even though there have been increasing interests and clinical challenges in esthetic improvement of these lesions, few of studies were reported for using non-invasive approach which is a very significant matter for child and young adults. This study was conducted to assess clinical effect on the improvement in color of these lesions via resin infiltration method developed as minimum invasive technique for white spot. For the 38 maxillary anterior teeth with calcification problem, the changes in color between before- and after- infiltration treatment, were evaluated and summarized as following. 1. A week after infiltration, 25% of developmental defects and 61% of decalcification lesions were improved in color as the value of ${\Delta}E $ below 3.7. 2. 40% of the developmental defects and 6% of decalcification lesions showed no significant change. 3. The developmental defects showed more remarkable changes in color 1 week after infiltration rather than immediately after the treatment. From our study results, it is considered that the amount of color improvement depended on the depth of lesion. In other words, for the lesion having more depth than the depth infiltrant resin can penetrate into, infiltration treatment showed no significant effect. Therefore, for clinical indication of resin infiltration treatment, further research on precise measurement technique of lesion depth is strongly required.

• Restorative Dentistry and Endodontics
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• v.27 no.3
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• pp.249-256
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• 2002

The use of flowable composite resins as liners in class II packable composite restoration has been suggested by some manufacturers. However, the contributions of this technique are unproven. The purpose of this study was to compare the gingival microleakage in class II packable composite restorations with or without the use of flowable composite resins as liners. Slot cavities were prepared on both proximals of 80 extracted human molars and randomly assigned to 8 groups of 20 each. The gingival margins were located at 1mm above CEJ in 80 cavities (group1-4) and 1mm below CEJ in 80 cavities (group5-8). The prepared teeth were mounted in the customized tray with adjacent teeth to simulate clinical conditions and metallic matrix band (Sectional matrix) and wooden wedges were applied. After acid etching and application of Single Bond, each group was restored with the following materials using incremental placement technique: Group 1,5 (Filtek P60), group 2, 3, 4 and group 6, 7, 8 (AeliteFlo, TetricFlow, Revolution/ Filtek P60). All specimens were thermocycled 500 times between 5$^{\circ}C$ and 55$^{\circ}C$ with 1 mimute dwell time, immersed 2% methylene blue dye for 24 hours and then rinsed with tab water. The specimens were embedded in clear resin and sectioned longitudinally through the center of restoration with a low speed diamond saw. Dye penetration at gingival margin was viewed at 20 magnification and analyzed on a scale of 0 to 4. Kruscal-Wallis One way analysis and Mann-Whitney Rank sum test were used to analyze the results. The results of this study were as follows. 1. The leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. On the enamel margin, packable composite resins with flowable liners showed lower leakage than those without flowable liners, but there were no significant differences among the four groups(P>0.05). 3. On the dentin margin, four groups demonstrated moderate to severe leakage, and there were no significant differences in leakage values(P>0.05).

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.334-346
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• 1997

Incidence of using esthetic composite resin in the posterior area is increasing but there were lots of inconsistent reports about their microleakage and marginal adaptation. The purpose of this study was to evaluate the differences of microleakage and marginal adaptation according to restorative techniques. 30 cavities with enamel gingival margin were prepared and restored with 3 types of composite resin [Z-100($Scotchbond^{TM}$ MP), AELITEFIL ($Onestep^{TM}$), Her culite XRV(Fuji BOND LC)] in direct technique and another 30 cavities were restored with preformed CR inlays and 3 different modern resin and resin-modified GI cements (Superbond C&B, Choice, Fuji Duet). Samples were chemically stressed in 75% ethanol for 24 hours and were thermocycled (5-$55^{\circ}C$(500 times. The degree of microleakage through proximal and gingival margins was examined by 1 % MB dye and the degree of marginal adaptation by examining the margins via SEM. The following results were obtained ; 1. In direct groups, Herculite XRV [Fuji BOND LC, 35.13 (15.50) %] group showed statistically different, less microleakage than Z-100 [$Scotchbond^{TM}$ MP, 72.91 (16.91 %] group and AELITEFIL [One-step, 93.73 (13.66) %] group (p<0.05). 2. In indirect groups, the degree of microleakage in Mean(S.D.) were: Super bond C & B [39.00 (24.35) %], Choice [57.19 (33.80) %], Fuji Duet [58.22 (40.36) %]. But there was no significant difference. 3. There was no significant difference between resin cement and resin-modified GI cement. 4. There were gaps at the interface with the tooth structure, but no gap was seen at the interface with restoration in all specimens. 5. In direct groups, Herculite XRV(Fuji BOND LC) group made little gap compared with other groups, but 40-$50{\mu}m$ thickness of bonding agent, Fuji BOND LC, looked like a cement used in indirect technique. 6. All indirect groups showed a variety of cement thickness, from less than $20{\mu}m$ to over $100{\mu}m$ and that dimension of buccal/lingual margin was less than that of gingival margin.

• Restorative Dentistry and Endodontics
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• v.26 no.1
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• pp.32-40
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• 2001

The aim of this study was to evaluate the effect of various polymerization techniques on the microleakage of compomer restorations. Fifty extracted human premolars and molar were used and randomly divided into 5 groups. After cavity preparation, compomer (F2000$^{\circledR}$) was filled according to the manufacturer's directions. All groups, except group 5, were filled using an incremental technique. Group 1 was polymerized for 40 seconds at a continuous 485mW/$\textrm{cm}^2$ with a VIP$^{\circledR}$(Bisco, USA) light cure unit. Group 2 was polymerized for 20 seconds at 345mW/$\textrm{cm}^2$ and then for 20 seconds at 645mW/$\textrm{cm}^2$ with the VIP equation omitted light cure unit. Group 3 was polymerized at 400mW/$\textrm{cm}^2$, gradually increased to 50mW/$\textrm{cm}^2$ 10 seconds until 550mW/$\textrm{cm}^2$ was reached; total 40 seconds with a Spectrum 800$^{\circledR}$ (Dentsply Caulk, USA) light cure unit. Group 4 was polymerized for 3 seconds using an incremental technique with a Flipo$^{\circledR}$ (LOKKi, France) light cure unit. Group 5 was polymerized for 3 seconds using a bulk fill technique with the Flipo$^{\circledR}$ light cure unit. The specimens were embedded with acrylic resin, and were sectioned with diamond saws in a mesiodistal direction along the longitudinal axis of the tooth so as to pass through the center of the restoration, and three surfaces (occlusal, pulpal, and gingival) were examined with SEM. The results were as follows ; 1. Group 5 showed a significantly larger gaps compared to other groups on the gingival, occlusal, and pulpal walls. 2. All groups except group 5 had no statistically significant gap on the gingival, occlusal, and pulpal walls. 3. There was no significant correlation between the amount of enamel on the gingival and occlusal walls and polymerization shrinkage.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.570-577
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• 1999

Intuitively, higher bond strengths should result in less leakage. However, the relationship between bond strengths and microleakage value is complex and not clearly understood. The purpose of this study was to evaluate the relationship between tensile bond strengths and microleakage values in the same restorations to understand the behavior of resin bonding to tooth structure. One-hundred and twenty enamel or dentin specimens from freshly extracted bovine mandibular incisors were used. The specimen was treated with 32% phosphoric acid for 15 seconds and rinsed for 20 seconds. the teeth were divided into four groups by means of wet bonding technique or dry bonding. One-Step$^{TM}$ adhesive were applied to the specimen. The specimens were immersed in 2% methylene blue solution for 7 days, and tensile bond strength and microleakage were measured. The results were as follows: 1. Significant negative correlation was found between bond strengths and micro leakage values. Hence, higher bond strengths seem to be associated with lower microleakage, and vice versa (r=-0 50, p<0.05). 2. The Enamel/Wet group showed significantly higher bond strength than Enamel/Dry one, and Dentin/Wet group showed higher strength than Dentin/Dry one (p<0.05). 3. Microleakage was significantly less ill wet bonding than in dry one at dentin (p<0.05), however, there was no significant difference between wet and dry bonding at enamel (p>0.05).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.377-392
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• 1991

The aim of this study was to investigate the thickness of alveolar lamina dura and alveolar bone height by the change of periodontal status. The periapical radiograms of the 853 cases were taken by paralleling technique. The conclusions from this study were as follows: 1. In the normal periodontal status, the alveolar lamina dura was the thickest at alveolar crest, followed by apex, midroot, and the average thickness of the posterior teeth was thicker than that of the anterior teeth. 2. In Russel's Periodontal Index 0 and 1, no significant differences of thickness were found to be 3 areas. In Russel's Periodontal Index 2 and 6, the thickness of alveolar lamina dura at alveolar crest was decreased, only. 3. In Russel's Periodontal Index 0 and 1, distance from the cemento-enamel junction to the alveolar crest was within 1.5㎜. In Russel's Periodontal Index 2 and 6, the distance was 3. increased over 1.5㎜.