• The korean journal of orthodontics
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• v.41 no.3
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• pp.184-190
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• 2011

Objective: The purpose of this study was to investigate the relationship between the enamel thickness of proximal surfaces and the morphologic features of mandibular incisors. Methods: Mesiodistal/faciolingual (MD/FL) index, MD width, and height of contour width/cervical width ratio were measured in 40 incisors extracted from Koreans. For determining the height of contour width/cervical width ratio, the cervical width was measured as the distance between proximal cementoenamel junctions. Then, the labial surface was ground to the height of the contour level to measure enamel thickness. Pearson correlation analysis was used to investigate the correlation between enamel thickness and morphologic features. Results: Enamel thickness was $0.75{\pm}0.07mm$ per side, and MD width was $5.56{\pm}0.40mm$. Enamel thickness and MD width were significantly correlated. However, a significant relationship was not observed between enamel thickness and MD/FL index or the height of contour width/cervical width ratio. Conclusions: The results suggest that enamel thickness is affected only by MD width. Therefore, if the MD width is the same for mandibular incisors with a large MD/FL index or triangular shape and mandibular incisors with normal shape, then the limit of enamel reduction for reproximation will be the same.

• Restorative Dentistry and Endodontics
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• v.35 no.1
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• pp.1-4
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• 2010

The final preparation (MAF) size in infected root canals is still controversial. Nonetheless, recent studies demonstrated that larger apical preparation sizes produces a greater reduction in remaining bacteria and dentinal debris as compared to smaller apical preparation sizes. Therefore, clinicians should be practiced with treatment strategies guided by evidence-based information, especially in infected/failed root canals.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.91-95
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• 2009

The use of stainless steel crowns are indicated for restoration of primary or permanent molars with proximal dental caries, extensive dental caries, or previous pulp treatment with increased danger of tooth fracture. Stainless steel crowns were introduced by Humphrey in 1950. For their improved durability, longevity, and success rate, they have been strongly considered for restoring extensive and multi-surfaced dental caries of molars in pediatric dentistry. However, they also have shortcomings, such as possibility of pulpal exposure or damaging proximal surface of adjacent teeth. In addition, when oversized stainless steel crowns are used, eruption of the adjacent permanent teeth may be disturbed by their prominent margin. As a means to compensate the shortcomings of stainless steel crowns, use of orthodontics bands may be considered. It is an alternative restoration method, where an orthodontic band is placed on a tooth first and cavity is restored with filling material, such as composite resin, glass ionomer, or amalgam. The use of an orthodontic band is indicated for molar restoration with cervical dental caries, extensive dental caries, enamel hypoplasia, or previous pulp treatment. Because it requires shorter chair time compared to stainless steel crown, its application is very useful for children with poor behavior. However, restoration using an orthodontic band requires good oral hygiene after its application. This case report illustrates the conservative restoration of primary molars and permanent molars with extensive dental caries using orthodontic bands.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.1
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• pp.41-56
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• 2018

The purpose of this study was to provide clinical recommendations for restoration with selection of the most similar zirconia crown by 3-dimensional analysis of the shape of the maxillary primary central and lateral incisors in Korean individuals and prefabricated zirconia crowns. The average shape of the sound maxillary primary central and lateral incisors in 300 children was reproduced by 3-dimensional scanning. Zirconia crowns of 4 manufacturers (NuSmile $ZR^{(R)}$ Crown, Cheng $Crowns^{(R)}$, Kinder $Krowns^{(R)}$, and EZ $Pedo^{(R)}$ Crown) were scanned 3-dimensionally, and coordinates for comparison of the shape were measured to evaluate the similarity between the teeth and crowns. The most similar crowns were selected by comparing the mesiodistal length, crown height, crown shape ratio, distance between the same coordinates of a tooth and crown, the radius of curvature of the labial surface, and the volume. As a result of analysis, Cheng $Crowns^{(R)}$ size 3 and NuSmile $ZR^{(R)}$ Crown size 2 were the most similar crowns in the maxillary primary central and lateral incisors, respectively. Scanning the inner surface of the crowns and evaluating the amount of tooth reduction required suggested that an overall lesser amount of tooth reduction compared to that presented by the manufacturer's guidelines should be performed.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.125-131
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• 2002

When a tooth is fracture with the pulp exposure, and if a fragment is large enough to save, reattachment of the fragment would be a choice of treatment and reattachment of the fragment provides several advantages over other forms of dental restoration following crown fracture. For the purpose of tooth reattachment, it is important to preserve the sound enamel around fracture area. For young patients, tooth reattachment has more advantages in the sense that they recover faster and that it enables other treatments at the same time. Through the continuous advancement in adhesion technology and the effort for aestheticism, various reattachment methods have been practiced and more efforts are considered necessary. The presented cases are that we had practiced in our department in Kyung Hee Medical center, I may address that fragmentation has been successfully done with aesthetically fine results, and no pathologic changes were found in short term follow-ups.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.327-334
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• 2007

The purpose of this study was to evaluate the effect of burs on microleakage of Class V resin restorations when a self-etching primer adhesive was used. Forty Class V cavities were prepared with four different cutting burs on extracted third molars, and divided into one of four equal groups (n = 10); Group 1-plain cut carbide bur (no. 245), Group 2-cross cut carbide bur (no. 557), Group 3-fine diamond bur (TF-21F), Group 4-standard diamond bur (EX-41). The occlusal and gingival margin of cavities was located in enamel and dentin, respectively. Cavities were treated with Clearfil SE Bond and restored with Clearfil AP-X. Specimens were thermocycled, immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed leakages at enamel and dentinal margins. Data were analyzed using Mann-Whitney and Wilcoxon signed ranked test. The results of this study were as follows; 1. At enamel margin, microleakage of group 4 was statistically higher than those of group 1, 2 and 3 (p < 0.01). 2. At dentinal margin, microleakage of group 4 was statistically higher than group 3 (p < 0.01), but group 1 and 2 were not statistically different with group 3 and 4. 3. Enamel microleakage was statistically higher than dentinal microleakage in group 1, 2 and 3 (p < 0.05), but statistical difference between the microleakage of enamel and dentinal margin was not in Group 4. In conclusion, the use of coarse diamond bur showed high microleakage at both enamel and dentinal margin when Clearfil SE Bond was used in class V cavity.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.211-218
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• 2019

Purpose: The purpose of the present study was to compare the accuracy of four different metal copings fabricated by CAD/CAM technology and to evaluate clinical effectiveness. Materials and methods: Composite resin tooth of the maxillary central incisor was prepared for a metal ceramic crown and duplicated metal die was fabricated. Then scan the metal die for 12 times to obtain STL files using a confocal microscopy type oral scanner. Metal copings with a thickness of 0.5 mm and a cement space of $50{\mu}m$ were designed on a CAD program. The Co-Cr metal copings were fabricated by the following four methods: Wax pattern milling & Casting (WM), Resin pattern 3D Printing & casting (RP), Milling & Sintering (MS), Selective laser melting (SLM). Silicone replica technique was used to measure marginal and internal discrepancies. The data was statistically analyzed with One-way analysis of variance and appropriate post hoc test (Scheffe test) (${\alpha}=.05$). Results: Mean marginal discrepancy was significantly smaller in the Group WM ($27.66{\pm}9.85{\mu}m$) and Group MS ($28.88{\pm}10.13{\mu}m$) than in the Group RP ($38.09{\pm}11.14{\mu}m$). Mean cervical discrepancy was significantly smaller in the Group MS than in the Group RP. Mean axial discrepancy was significantly smaller in the Group WM and Group MS then in the Group RP and Group SLM. Mean incisal discrepancies was significantly smaller in the Group RP than in all other groups. Conclusion: The marginal and axial discrepancies of the Co-Cr coping fabricated by the Wax pattern milling and Milling/Sintering method were better than those of the other groups. The marginal, cervical and axial fit of Co-Cr copings in all groups are within a clinically acceptable range.

• Restorative Dentistry and Endodontics
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• v.32 no.5
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• pp.437-444
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• 2007

The purpose of this study was to compare the marginal microleakage of different 2-step adhesive systems in Class V cavities prepared with different diamond points. Forty Class V cavities were prepared with two different (coarse or fine) diamond points on cervical third of extracted molars. The occlusal and gingival margin of cavities was located in enamel and dentin, respectively. They were divided into one of four equal groups (n = 10) and ; Group 1-prepared with coarse diamond point (EX-41), restored with Single Bond and Z 250, Group 2-prepared with fine diamond piont (TF-21F), restored with Sing)e Bond and Z 250, Group 3-prepared with coarse diamond point (EX-41), restored with Clearfil SE Bond and Clearfil AP-X, Group 4-prepared with fine diamond point (TF-21F), restored with Clearfil SE Bond and Clearfil AP-X. Specimens were thermocycled, immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed leakages at enamel and dentinal margins. Data were analyzed using Mann-Whitney and Wilcoxon signed ranked test. In this study, marginal microleakage or Single Bond was not affected by type of diamond points. But Clearfil SE Bond showed higher marginal microleakage at both enamel and dentinal margin when Class V cavity was prepared with coarse diamond point.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.194-201
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• 2011

A dentigerous cyst is the most common developmental odontogenic cyst. Patients with dentigerous cyst usually feel no pain or discomfort. If it is not treated, tooth eruption might not only be impeded, but also let the tooth translocate to the unusual area. So, early detection and appropriate treatment are important. Enucleation & marsupialization are the best options to treat a dentigerous cyst. Treatment plan depends on patient's age, health, preserve & protect of important structures, and sort of cyst. In these dentigerous cysts cases, by marsupialization and using obturator, affected tooth could be achieved spontaneous eruption into the dental arch even though they were badly dislocated.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.88-95
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• 2010

The purpose of this study was to compare the root canal shaping ability of 4 rotary NiTi instruments in simulated root canals. For the preparation of thirty two curved root canals, Mtwo instruments using "single length"technique, and Profile, ProTaper Universal, and K3 using crown-down technique (N = 8) were used. All canal samples were prepared by reaching an apical canal size of #30. Pre- and post-instrumentation digital images were recorded and an assessment of canal shape was determined using a computer image analysis program SigmaScan Pro (Systat Software Inc., San Jose, CA, USA). The changes of the dimension of inner walls of canals, (2) the changes of the dimension of outer walls of canals, and (3) the centering ratio were measured at 7 measuring points, and then data were statistically analyzed using one-way ANOVA and Duncan's test. The results were as below; 1. The root canal shaping ability of Profile was significantly faster than that of other rotary NiTi instruments (p < 0.05). 2. The deformation and fracture of all instruments used for this study were not experienced. 3. In the degree of changes of the dimension of inner walls of canals, Profile demonstrated the lowest changes of the dimension of inner walls of canals except at the measuring points of the 1 and 2 mm (p < 0.05). However, the ProTaper Universal showed the highest changes of the dimension of inner walls of canals at all measuring points (p < 0.05). 4. In the degree of changes of the dimension of outer walls of canals, Mtwo demonstrated the lowest changse of the dimension of outer walls of canals except at the measuring point of the 1 mm (p < 0.05). However, Profile exhibited the highest changes of the dimension of outer walls of canals at the measuring points of 3 and 4 mm and ProTaper Universal and K3 showed the largest changes of the dimension of outer walls of canals at the measuring points of 1, 2, 6, and 7 mm (p < 0.05). 5. In degree of centering ratio, Profile demonstrated the least centering ratio comparing with the centering ratio shown by other NiTi instruments at the measuring points of 1, 4, 5, and 6 mm. Results suggest that in the coronal part of canal preparation, active cutting files such as ProTaper Universal may efficiently flare the canal orifice and form a better taper, and in the apical part of the canal, files which have a better centering ability such as Profile may maintain the original canal curvature and reduce the shaping time.