• Imaging Science in Dentistry
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• v.30 no.3
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• pp.155-158
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• 2000

The purpose of this paper is to explain the making procedure and the usage of receiver operating characteristic (ROC) curve for interpretation of radiographic images. The conventional radiograms obtained after the creation of the lesions in the acrylic plates and were enhanced in color. The observer were informed of which tooth to examine, the 'a priori' probability of a lesion present and the approximate diameter of the lesions. The two groups of films were interpreted separately by the same observer using the same rating scale. The following rating scale was used: A; definitely no lesion, B; probably no lesion, C; not sure, D; probably a lesion, and E; definitely a lesion. In analysis, for each observer the diagnostic results in terms of true positive (TP) and false positive (FP) decisions were plotted on a graph. The lowest point on the graph represents the TP and FP when only decisions designated as E according to the rating scale are included. The next point shows the TP and FP values when diagnoses designated as D are added and so forth. By connecting such plot points, a receiver operating characteristic (ROC) curves is obtained. The area under the curve represents the diagnostic accuracy resulting from a diagnostic performance at pure chance level and a value of 1.0 at perfect performance. This method has been known as an useful method to detect the minute difference for each radiographic technic, each observer and for the different lesion depths.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.110-117
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• 2008

Clinical performance of resin-based composite material depends on case selection and on the proficiency of the operator. Especially, composite resin restoration on permanent first molar in children have more limitations clinically than adult patients according to stage of tooth eruption and patient's compliance. This study was designed to evaluate the clinical performance of posterior composite resin restoration in children after 5 years. 35 teeth of 16 patients who were received composite resin restoration on permanent first molar in Department of Pediatric dentistry, Pusan National University Hospital between January 2001 and December 2001 were evaluated based on Modified USPHS criteria. From the finding in this study, following conclusions can be made. 1. 6 teeth(17%) of 35 teeth was replaced, so 5-years survival rate of posterior composite resin restoration is 82.9%. 2. As results of each evaluation criteria, on color match, anatomic form, surface roughness, sensitivity/ discomfort, ideal A grade score was 86.2%, 93.1%, 86.2%, 86.2%, clinically accepted B grade score was 13.8%, 0%, 13.8%, 10.3%. On marginal adaptation and marginal discoloration, A grade score was 13.8%, 44.8% and B grade score was 79.3%, 34.5% and secondary caries rate was 20.7%. 3. 69.1% of teeth (20 teeth) was clinically accepted on all evaluation criteria.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.522-528
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• 2006

When tooth is displaced within the alveolar bone, it could apply pressure and rupture the apical vessels. Pulpal reaction in such case is affected by the stage of root formation, amount of intrusion and pulpal infection. Determining the need of pulp treatment depends on the pulp vitality. Therefore, periodic vitality tests, coronal color changes and radiographic root resorption signs should be observed through periodic post-trauma follow-up. Pulp necrosis, pulp canal obliteration, external root resorption, root ankylosis and marginal bone loss could result from periodontal injuries. Negative sign changes from positive signs of vitality tests suggest pulp necrosis. In this case, pulp treatment should be held before root resorption occurs. By comparing the following two cases, complications of intrusion and factors producing them could be confirmed, thus we propose to report these two cases.

• Journal of dental hygiene science
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• v.8 no.4
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• pp.255-260
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• 2008

The purposes of this study were to examine the effect of 35% hydrogen peroxide (HP) bleaching agent on the changes in physical and chemical characteristics of tooth. The bleached teeth showed an apparent color changes. The whiteness increased linearly within the tested period as the period of bleaching increased. The microhardness between bleached groups after bleaching showed any statistically significant difference according to the paried t-test. The bleached enamel surface showed any apparent morphological changes compared to the enamel which was stored in distilled water only. The difference of the total mineral contents for the distilled water and hydrogen peroxide did not show statistical significance. These results demonstrated that bleaching using 35% hydrogen peroxide were adversely affects application time of experimental group and may confirm the safety of using these agents for a short time in dentist-monitored bleaching.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.26 no.1
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• pp.17-23
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• 2017

Purpose: This retrospective study is to evaluate whether the timing of implant placement and the result of esthetic outcomes are related. Materials and Methods: Among the patients who had undergone single implant surgery on anterior area from 2010 to 2013 in Veterans Health Service Medical Center, 34 implants in 27 patients (24 male and 3 female) were selected and categorized into 3 groups according to the timing of placement, which are group D (Delay), group E (Early) and group I (Immediate). Aesthetic indices used included the Pink Esthetic Score (PES). It has 7 variables scores, such as mesial papilla, distal papilla, a level of soft-tissue margin, soft-tissue contour, alveolar process, soft-tissue color, and soft-tissue texture. Each variable ranges from 0 to 2, therefore total 14 points are highest. All patients were received by regular follow-up at least 1-year. One examiner measured PES on the intraoral photos. Each patient was considered as a statistical unit for statistical analysis. Statistical analyses were performed using a commercially available statistical software (SPSS Statistics 21.0, IBM Corp., Armonk, NY, USA). Kruskal-Wallis test was used for inter-group comparisons. Statistical significance was set at P<0.05. Result: Mean score in Group D, Group I, and Group E were $11.5{\pm}1.5$, $11.4{\pm}1.8$, and $11.3{\pm}1.8$ respectively. In Kruskal-Wallis test, there are no differences (P=0.989). Conclusion: In this limited study suggests that clinical aesthetic results can be achieved with all treatment protocols. Finally, various factors can be considered to produce the esthetic results.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.269-281
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• 2006

This study evaluated the effectiveness and safety of an experimental bleaching strip (Medison dental whitening strip. Samsung medical Co., Anyang, Korea) containing 2.9% hydrogen peroxide. Twenty-three volunteers used the bleaching strips for one and a half hour daily for 2 weeks. As control group. the same strips in which hydrogen peroxide was not included were used by 24 volunteers with the same protocol. The shade change (${\Delta}E^{*}$, color difference) of twelve anterior teeth was measured using Shade Vision (X-Rite Inc., S.W. Grandville, MI, USA). Chroma Meter (Minolta Co., Ltd. Osaka. Japan) and Vitapan classical shade guide (Vita Zahnfabrik, Germany). The shade change of overall teeth in the experimental group was significantly greater than that in the control group (p < 0.05) and was easily perceivable. The change resulted from the increase of lightness (CIE $L^{*}$ value) and the decrease of redness (CIE $a^{*}$ value) and yellowness (CIE $b^{*}$ value). The shade change of individual tooth was greatest in canine. and smallest in central incisor. The safety of the bleaching strip was also confirmed.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.168-174
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• 2022

In case of gingival recession or bone defect in maxillary anterior implant treatment, it is not easy to obtain satisfactory clinical results. In this case, loss of the labial alveolar plate was diagnosed in the maxillary right central incisor, so after tooth extraction, soft tissue was secured and implant placement with bone graft was planned. In addition, digital guide surgery was performed for the ideal implant position, and GBR (Guided Bone Regeneration) was accompanied with the xenogeneic bone and the autologous bone collected from the mandibular ramus since alveolar bone defects were extensive. After a sufficient period of osseointegration of the implant, a temporary prosthesis was fabricated through secondary stage surgery and impression taking, and through periodic external adjustment, the shape of soft tissue was improved. In the final prosthesis fabrication, a color tone of natural teeth was induced by an gold anodized customized abutment, and an aesthetic and functional zirconia prosthesis with reproducing the shape of the temporary prosthesis through intraoral scan was delivered.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.1
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• pp.6-19
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• 2024

With the advancement of Computer-Aided Design/Computer-Aided Manufacturing (CAD-CAM) technology, fabrication of dentures using this technology has gained popularity. As one of CAD-CAM technologies, digital complete denture system has been introduced, which fabricates complete dentures using subtractive manufacturing of monolithic block containing both the color of a denture base and an artificial tooth. In this case, two pairs of upper and lower dentures were fabricated for two patients. Two pairs of complete dentures were fabricated for a 74-year-old male and a 73-year-old female respectively by conventional denture fabrication method and digital method of milling. To obtain a digital complete denture, monolithic block (Ivotion, Ivoclar Vivadent, Schaan, Liechtenstein) was chosen for the materials to fabricate the digital complete dentures. An individual tray was designed using CAD software and manufactured by 3D printing technique. The final impression and interocclusal relationship were recorded using the fabricated individual tray. The final impression was scanned, and the complete denture design and try-in denture were 3D printed using CAD-CAM software. Subsequently, the monolithic block was milled, and the final dentures were fabricated and tried on patients. Previously mentioned two patient cases compared and analyzed stability, fit, speaking, mastication, aesthetics, and patient satisfaction of two pairs of dentures: one fabricated using CAD-CAM system and the other using traditional methods. This was performed to evaluate and report the findings from both denture-making approaches.

• The korean journal of orthodontics
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• v.31 no.6 s.89
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• pp.559-566
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• 2001

This study was undertaken to demonstrate the forces in the mandibular alveolar bone generated by activation of the mandibular posterior crossbite appliance in the treatment of buccal crossbite caused by lingual eruption of mandibular second molar. A three-dimensional photoelastic model was fabricated using a photoelastic material (PL-3) to simulate alveolar bone. We observed the model from the anterior to the posterior view in a circular polariscope and recorded photogtaphically before and after activation of the mandibular posterior crossbite appliance. The following results were obtained : 1. When the traction force was applied on the buccal surface of the mandibular second molar, stress was concentrated at the lingual alveolar crest and root apex area. The axis of rotation also was at the middle third of the buccal toot surface and the root apex, so that uncontrolled tipping and a buccal traction force for the mandibular second molar were developed. 2. When the traction force was applied on the lingual surface of the mandibular second molar more stress was observed as opposed to those situations in which the force application was on the buccal surface. In addition, stress intensity was increased below the loot areas and the axis of rotation of the mandibular second molar was lost. In result, controlled tipping and intrusive tooth movements were developed. 3. When the traction forte was applied on either buccal or lingual surface of the second molar, the color patterns of the anchorage unit were similar to the initial color pattern of that before the force application. So we can use the lingual arch for effective anchorage in correcting the posterior buccal crossbite. As in above mentioned results, we must avoid the rotation and uncontrolled tipping, creating occlusal interference of the malpositioned mandibular second molar when correcting posterior buccal crossbite. For this purpose, we recommend the lingual traction force on the second molar as opposed to the buccal traction.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.4
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• pp.406-415
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• 2009

Purpose: The purpose of this study was to compare the marginal fitness and fracture load of the zirconia copings according to the design with different thickness and coloration. Material and methods: The evaluation was based on 80 zirconia copings. Zirconia copings were fabricated in design with different thicknesses using CAD/CAM system (Everset, KAVO dental GmbH, Biberach, Germany). The designs of copings were divided into four groups. The first group consisted of copings with uniform thickness of 0.3 mm. The thickness in the second group was 0.3 mm on the buccal surface and 0.6 mm on the lingual surface. The third group consisted of coping with uniform thickness of 0.6 mm. The thickness in the fourth group was 0.6 mm on the buccal surface and 1mm on the lingual surface. Each group consisted of 10 colored and 10 uncolored copings. Half of the copings (40) processed with a milling system according to the specific design were sent to be given a color (A3) through saturation in special dye by a manufacturing company. Just after sintering, the marginal discrepancies of copings were measured on the buccal, lingual, mesial and distal surfaces of metal die, under a Video Microscope System (sv-35, Sometech, Seoul, Korea) at a magnification of $\times$ 100. It was remeasured after the adjusting of the inner surface. Next, all copings were luted to the metal dies using reinforced cement {GC FujiCEM (GC Corp. Tokyo, Japan)} and mounted on the testing jig in a Universal Testing Machine (Instron 4467, Norwood, MA, USA). The results were analyzed statistically using the one-way ANOVA test. Results: The obtained results were as follow: 1. The measured value of marginal discrepancy right after sintering was the greatest in the contraction of the buccal area in all groups, except for group I2. 2. There was no significant difference of marginal fitness among the groups in the colored zirconia group (P<.05). 3. When the marginal fitness among the groups in the uncolored zirconia group was considered, group II2 had the smallest marginal discrepancy. 4. When the colored and uncolored groups with the same design were compared, there was a significant difference between I1 and II1 groups. In group 2, 3, and 4, the uncolored zirconia had the greatest marginal fitness (P<.05). 5. After adjustment of inner surface, there was no significant difference in the marginal fitness in all groups when color and design of the zirconia coping were compared. 6. The fracture load of CAD/CAM zirconia copings showed significant difference in group 1, 2, 3, and 4. I4 and II4 had the strongest fracture load. 7. When groups with different color and same design were compared, all colored groups showed greater fracture load (P>.05), with no significance. Conclusion: There was difference in the marginal fitness according to the design and coloration of zirconia copings right after sintering, but it was decided that the copings may well be used clinically if the inner surface are adjusted. The copings should be thick enough for the reinforcement of fracture strength. But considering the esthetics of the visible surfaces (labial and buccal surface), the thickness of copings may be a little thin, without giving any significant effect on the fracture strength. This type of design may be considered when giving priority to preservation of tooth or esthetics.