Purpose: Measuring viability of a three-dimensional in vitro organotypic human oral tissue model has been suggested as an alternative test method to the oral mucosa irritation test of oral care products. The aim of this study was to investigate the production of two different cytokines using organotypic human oral tissue model following exposure to chemicals that are commonly used in oral care products. Materials and Methods: The organotypic human oral tissues were exposed to ethanol, sodium lauryl sulphate or hydrogen peroxide for 90 minutes. Following exposure, interleukin (IL)-1α and IL-8 productions were assessed and correlated with cell viability testing as well as histology of the organotypic human oral tissues. Result: High levels of IL-8 were released from organotypic human oral tissues in all of the test and control groups without any significant differences between them. In contrast, differences were found in IL-1α release between the test and control groups. Additionally, the trend of IL-1α release corresponded to the phenotypes observed in histological analysis while different trend existed between IL-1α release and cell viability. Conclusion: The study concluded the non-specific release of IL-8 for the assessment of oral care product chemicals' toxicity, while potential of measuring IL-1α cytokine level as the possible alternative test method.

Purpose: The aim of this study was to investigate the outcomes of endodontic treatment of mandibular second molar with C-shaped canal in elderly patients and related factors affecting the survival of the tooth. Materials and Methods: From 2010 to 2015, the survival rate following endodontic treatment was evaluated in elderly patients over 60 years who visited the Veterans Health Service Medical Center for endodontic treatment. The presence of C-shaped canals was confirmed using clinical records and radiographic features. Patient's age, sex, systemic diseases, tooth location, vitality, signs and symptoms, fractures, caries, apical radiolucency, canal shaping methods, sealer leakage, filling voids, and restoration of prosthesis were included in the analyses as confounding variables. The survival rate of teeth was analyzed using Kaplan-Meire analysis and the relationship between the survival rate and variables was analyzed using Simple and Multiple Cox regression analysis. Result: In total, 107 teeth in elderly patients had C-shaped canal. The survival rate of teeth that received endodontic treatment was 63.70%. None of the factors investigated significantly influenced the survival rate (P>0.05). Conclusion: In elderly patients with C-shaped canal, the survival rate after root canal treatment was not significantly different from that of other mandibular molars.

Purpose: The primary objective of this study was to evaluate the change in the temperature of the adhesive resin in polycrystalline ceramic brackets irradiated using a diode laser at different irradiation energy levels and times. Materials and Methods: For the measurement of the temperature of the adhesive resin, it was applied at the base of the ceramic bracket, a thermocouple was placed at the center of the base surface, the bracket was placed on prepared resin specimens for light curing, and a laser was irradiated to the center of the bracket slot at 5, 7, and 10 W. For the measurement of the temperatures of the enamel under the bracket and pulp cavity, extracted premolar was fixed to a prepared mold and the ceramic bracket was bonded to the buccal surface of the premolar. The Kruskal-Wallis H test and Friedman test were used for statistical analysis. Result: At 5 W, the temperature of the adhesive resin did not reach the resin softening temperature of 200℃ within 30 seconds. At 7 W, it reached 200℃ when the ceramic bracket was irradiated continuously for 28 seconds. At 10 W, it reached 200℃ when the ceramic bracket was irradiated continuously for 15 seconds. During laser irradiation, the temperature of the enamel under the bracket increased by over 5℃ within 15 seconds. Conclusion: The use of diode laser irradiation for bracket debonding should be carefully considered because the pulp cavity temperature increases by over 5℃ within the irradiation time for resin thermal softening.

Purpose: The technique introduced in this study describes a technique for surface treatment that applies a photocuring resin to the surface of an interim crown fabricated by three-dimensional (3D) printing without a conventional polishing method. The purpose of this study was to evaluate marginal and internal fit and the intaglio surface trueness of interim crowns after surface treatment of 3D-printed crowns for clinical application. Materials and Methods: An interim crown was fabricated using a 3D printer with digital light-processing technology, and the surface support was removed. After the posttreatment process, the resin was thinly applied to the surface of the interim crown and polymerized to solve the esthetic problem of the surface without the conventional polishing process. In addition, the marginal and internal fits were measured to verify the clinical use of this technique, and the trueness was evaluated to confirm the deformation of the inner surface according to the technical application of the outer surface of the interim crown. The difference before and after the evaluation by a statistical method was verified using an independent t-test (α=0.05). Result: There was no significant difference in the marginal and internal fit before and after the application of this technique (P>0.05). There was no significant difference in intaglio surface trueness before and after the application of this technique (P=0.963). Conclusion: There was no change in the marginal and internal fit or in intaglio surface trueness of the interim crowns to which this technology was applied. This surface treatment technique is a more convenient method for interim crowns fabricated using 3D-printing technology without the conventional polishing process.

Purpose: The aim of this study was to evaluate the degree of achievement of anterior tooth movement using a thermoplastic clear aligner by superimposing pretreatment, setup, and post-treatment models and to analyze the factors that influence it. Materials and Methods: Forty patients who underwent clear aligner treatment at the Department of Orthodontics were included in the study. The pretreatment, setup, and post-treatment models were superimposed, and the achievement rates were evaluated. We analyzed the factors that caused changes in achievement rate on each condition. Result: The average achievement rate of total tooth movement was 57.65%. Mesiodistal and anteroposterior displacements were achieved better than vertical displacement and rotation. In each displacement, posterior, mesial, and extrusive movements were better achieved than the rotation. Spacing was better corrected than crowding, especially in the mesiodistal direction. Most of the tooth movements were achieved better when using 3-step thicknesses of aligners were used. Conclusion: The treatment results of clear aligners may differ depending on the type of tooth movement, age and other treatment conditions. Clinicians should consider unfavorable conditions based on the results of this study.

Purpose: For minimally invasive procedures, three-dimensional (3D) anatomical knowledge of the structures of the face is essential. This study aimed to describe the thickness of the skin and subcutaneous tissue and depths of the facial muscles located in the infraorbital region using a 3D scanner to provide critical clinical anatomical guidelines for improving minimally invasive cosmetic procedures. Materials and Methods: The 3D scanning images of 38 Korean cadavers (22 males and 16 females; age range: 51~94 years at the time of death) were analyzed. Eight facial landmarks (P1~P8) were marked on the cadaveric faces. The images were scanned in three steps-undissected face, hemiface after skinning, and revealing the facial muscles. Student's t-test was used to identify significant differences. Result: The skin and subcutaneous tissue tended to become thicker from the upper to lower and medial to lateral aspects, and the muscles followed the same pattern as that of the most superficial located muscle and the deepest located muscles. No significant sex-related differences were found in the skin at any landmark. However, the muscles tended to be deeper in the female participants. Conclusion: The study data can serve as a basis for creating or enhancing clinical anatomy-based guidelines or improving procedures in the infraorbital region.

Purpose: The purpose of this article is to study the relationship of unintentionally extended split in the distal segment during the bilateral sagittal split ramus osteotomy (BSSRO) and skeletal relapse. Materials and Methods: Twenty patients with mandibular prognathism were divided into two groups according to whether or not unintentionally extended split had occurred. Cone-beam computed tomography images were taken before surgery (T0), immediately after surgery (T1), and postoperatively at 6 months (T2). The stability was evaluated by measuring the change of Nasion perpendicular-Pogonion (N-Pog) distance. Result: Both groups showed mild advancement of Pog during follow-up. In both groups, the condyle head rotated inward and moved posterioinferiorly after surgery, but tended to return to their original position during follow-up. Conclusion: There was no statistically significant difference between the two groups in mandible position. Moreover, the condylar position was stable. If it is difficult to proceed reduction of the unintentionally extended split, careful inspection should be performed to prevent subsequent complications during follow-up.