• The korean journal of orthodontics
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• v.45 no.6
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• pp.289-298
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• 2015

Objective: To evaluate and compare the effects of two appliances on the en masse retraction of the anterior teeth anchored by temporary skeletal anchorage devices (TSADs). Methods: The sample comprised 46 nongrowing hyperdivergent adult patients who planned to undergo upper first premolar extraction using lingual retractors. They were divided into three groups, based on the lingual appliance used: the C-lingual retractor (CLR) group (group 1, n = 16) and two antero-posterior lingual retractor (APLR) groups (n = 30, groups 2 and 3). The APLR group was divided by the posterior tube angulation; posterior tube parallel to the occlusal plane (group 2, n = 15) and distally tipped tube (group 3, n = 15). A retrospective clinical investigation of the skeletal, dental, and soft tissue relationships was performed using lateral cephalometric radiographs obtained pretreatment and post en masse retraction of the anterior teeth. Results: All groups achieved significant incisor and canine retraction. The upper posterior teeth did not drift significantly during the retraction period. The APLR group had less angulation change in the anterior dentition, compared to the CLR group. By changing the tube angulation in the APLR, the intrusive force significantly increased in the distally tipped tube of group 3 patients and remarkably reduced the occlusal plane angle. Conclusions: Compared to the CLR, the APLR provides better anterior torque control and canine tipping while achieving bodily translation. Furthermore, changing the tube angulation will affect the amount of incisor intrusion, even in patients with similar palatal vault depth, without the need for additional TSADs.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.280-289
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• 2016

Objective: The aim of this study was to analyze tooth movement and arch width changes in maxillary dentition following nonextraction treatment with orthodontic mini-implant (OMI) anchorage in Class II division 1 malocclusions. Methods: Seventeen adult patients diagnosed with Angle's Class II division 1 malocclusion were treated by nonextraction with OMIs as anchorage for distalization of whole maxillary dentition. Three-dimensional virtual maxillary models were superimposed with the best-fit method at the pretreatment and post-treatment stages. Linear, angular, and arch width variables were measured using Rapidform 2006 software, and analyzed by the paired t -test. Results: All maxillary teeth showed statistically significant movement posteriorly (p < 0.05). There were no significant changes in the vertical position of the maxillary teeth, except that the second molars were extruded (0.86 mm, p < 0.01). The maxillary first and second molars were rotated distal-in ($4.5^{\circ}$, p < 0.001; $3.0^{\circ}$, p < 0.05, respectively). The intersecond molar width increased slightly (0.1 mm, p > 0.05) and the intercanine, interfirst premolar, intersecond premolar, and interfirst molar widths increased significantly (2.2 mm, p < 0.01; 2.2 mm, p < 0.05; 1.9 mm, p < 0.01; 2.0 mm, p < 0.01; respectively). Conclusions: Nonextraction treatment with OMI anchorage for Class II division 1 malocclusions could retract the whole maxillary dentition to achieve a Class I canine and molar relationship without a change in the vertical position of the teeth; however, the second molars were significantly extruded. Simultaneously, the maxillary arch was shown to be expanded with distal-in rotation of the molars.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.415-421
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• 2021

The biomechanical prognosis of conventional removable partial denture is questionable in case of patient with few remaining teeth or periodontally compromised teeth. In this case, hybrid telescopic double crown RPD may be a successful treatment alternative. Hybrid telescopic double crown RPD has following advantages over conventional RPD: secondary splinting effect between abutments, more vertical stress direction and more convenient in repairing the denture after extraction of abutment tooth. In this clinical case, patient had deep overbite in anteriors and partially edentulous. The maxilla was restored with hybrid telescopic double crown RPD and the mandible was restored with implants and fixed prostheses. Long-term follow-up and supportive periodontal treatment were performed, and satisfactory results were achieved in terms of function and aesthetics.

• The Journal of the Korean dental association
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• v.57 no.3
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• pp.149-160
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• 2019

Atrophic alveolar ridge of maxillary anterior area is commonly observed after the extraction of teeth in patients with severely compromised periodontal disease, causing difficulties with implant placement. Successful esthetics and functional implant rehabilitation rely on sufficient bone volume, adequate bone contours, and ideal implant positioning and angulation. The present case report categorized the ridge augmentation techniques using guided bone regeneration (GBR) on the maxillary anterior site by Seibert classification. Case I patient presented for implant placement in the position of tooth #11. The alveolar ridge was considered a Seibert classification I ridge defect. Simultaneous implant placement and GBR were performed. Eight months after implantation, clinical and radiological examinations were performed. Case III patient presented with discomfort due to mobility of the upper maxillary anterior site. Due to severe destruction of alveolar bone, teeth #11 and #12 were extracted. After three months, the alveolar ridge was considered a Seibert classification III ridge defect. A GBR procedure was performed; implantation was performed 6 months later. Approximately 1-year after implantation, clinical and radiological examinations were performed. During the whole treatment period, healing was uneventful without membrane exposure, severe swelling, or infection in all cases. Radiographic and clinical examinations revealed that atrophic hard tissues and buccal bone contour were restored to the acceptable levels for implant placement and esthetic restoration. In conclusion, severely resorbed alveolar ridge of the maxillary anterior area can be reconstructed with ridge augmentation using the GBR procedure so that dental implants could be successfully placed.

• Journal of Biomedical Engineering Research
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• v.44 no.5
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• pp.346-353
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• 2023

In this paper, we propose an innovative approach that leverages deep learning to find optimal reference points for achieving precise tooth segmentation in three-dimensional tooth point cloud data. A dataset consisting of 350 aligned maxillary and mandibular cloud data was used as input, and both end coordinates of individual teeth were used as correct answers. A two-dimensional image was created by projecting the rendered point cloud data along the Z-axis, where an image of individual teeth was created using an object detection algorithm. The proposed algorithm is designed by adding various modules to the Unet model that allow effective learning of a narrow range, and detects both end points of the tooth using the generated tooth image. In the evaluation using DSC, Euclid distance, and MAE as indicators, we achieved superior performance compared to other Unet-based models. In future research, we will develop an algorithm to find the reference point of the point cloud by back-projecting the reference point detected in the image in three dimensions, and based on this, we will develop an algorithm to divide the teeth individually in the point cloud through image processing techniques.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.4
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• pp.229-236
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• 2023

Maxillary bone defects may follow surgical treatment of benign and malignant tumors, trauma, and infection. Palatal defects often lead to problems with swallowing and pronunciation from the leakage of air into the nasal cavity and sinus. Obturators have been commonly used to solve these problems, but long-term use of the device may cause irritation of the oral mucosa or damage to the abutment teeth. Utilizing implants in the edentulous area for the fabrication of the obturators has gained attention. This case report describes a patient, who had undergone partial resection of the maxilla due to adenocarcinoma, in need of a new obturator after losing abutment teeth after long-term use of the previous obturator. Implants were placed in strategic locations, and an implant-retained maxillary obturator was fabricated, showing satisfactory results in the rehabilitation of multiple aspects, including palatal defect, masticatory function, swallowing, pronunciation, and aesthetics.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.349-358
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• 1996

To extract or not to extract permanent teeth for the correction of malocclusion has been a great debate in the history of orthodontics, and there is a variety of analytic methods and criteria to aid in the diagnosis. Extraction formulas that has been presented are many analytic methods that depend on arch length discrepancy, dental prominence, and skeletal pattern of the each patients. Of these analysis, the most important diagnostic factor is patient's skeletal pattern. Because the behavior of the dentition is closely dependent upon the skeletal pattern of each patient, dentition must be arranged within that person's skeletal frame. EI(Extraction Index) is composed of CF, interincisal angle, and lip position. CF is made of ODI and APDI that differentiate vertical and horizontal component of the skeletal pattern. So, EI not only represents patient's skeletal pattern, but also takes facial appearance into consideration. This study was undertaken to investigate EI and related cephalometric variables on the cephalogram of Korean adolescents which consisted of 153 persons with normal occlusion, harmonious skeleton and pleasing face. The following conclusions were obtained. 1. The mean value of the ODI is $73.5^{\circ}$, APDI $82.5^{\circ}$, CF $156.3^{\circ}$ 2. The mean value of the interincisal angle is $123.6^{\circ}$ 3. The mean distance of upper lip to E-line is 0.0mm, lower lip to E-line is 1.4mm. 4. The mean value of the EI is $153.8^{\circ}$.

• The korean journal of orthodontics
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• v.32 no.3 s.92
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• pp.165-174
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• 2002

The purpose of this study was to compare on masse retraction of six anterior teeth with separate canine retraction in the amount of the anchorage loss and the retraction of the anterior teeth. The subjects consisted of 30 adult female patients with Angle Class 1 malocclusions who were treated by .022' straight wire appliance with 4 first permolar extraction. They were composed of two groups. Group 1 consisted of 15 subjects, whose six anterior teeth were retracted by on masse retraction. Group 2 consisted of 15 subjects, whose canines were retracted separately. Pre-treatment and post-treatment lateral cephalometric radiographs were analyzed. All data were processed statistically with independent samples t-test, and the conclusions were as follows. 1. There was no significant difference in the amount of the anchorage loss between two groups(p>0.05). 2. There was no significant difference in the amount of the retraction of the anterior teeth between two groups(p>0.05). 3. There was a significant difference in the amount of the inclinational change of the upper incisors between two groups. It was greater in Group 2. 4. There was a significant difference in the vertical positional change of the upper incisal edges between two groups. The upper incisal edges in Group 2 were more extruded than Group 1 by about 1mm. 5. There was no significant difference in the vertical positional change of the root apex of the upper incisors between two groups(p>0.05). And there was no significant difference in the vertical positional change of the upper molar(p>0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.2
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• pp.238-247
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• 2021

Congenital tooth agenesis is the most common developmental dental anomaly, of which oligodontia is defined as the absence of six or more permanent teeth, except the third molars. Tooth agenesis causes malocclusion, alveolar atrophy, aesthetic and psychosocial problems. This clinical report describes a multidisciplinary treatment for a patient diagnosed as oligodontia, who exhibited absence of 14 permanent teeth, atrophy of maxillary alveolar bone, and mandibular protrusion. Restoration space was secured and tooth axis was improved by the extraction of deciduous teeth and orthodontic treatment. However, edge-to-edge bite of posterior teeth and arch dimension discrepancy due to atrophic maxilla was remained. To restore the aesthetics and functionality, implant retained prosthesis was planned. Considering minimal bone grafts, location and number of dental implants and prostheses design were determined. Through the gradual adjustment of provisional restoration, the appropriate centric and eccentric occlusion was reflected into a definitive prosthesis. Currently, stable functional results were attained, however, regular follow up and maintenance care over lifetimes should be performed.

• Imaging Science in Dentistry
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• v.54 no.2
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• pp.129-137
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• 2024

Purpose: Patients with head and neck cancer (HNC) who undergo dental procedures during radiotherapy (RT) face an increased risk of developing osteoradionecrosis (ORN). Accordingly, new tools must be developed to extract critical information regarding the dose delivered to the teeth and mandible. This article proposes a novel approach for visualizing 3-dimensional planned dose distributions on panoramic reconstruction computed tomography (pCT) images. Materials and Methods: Four patients with HNC who underwent volumetric modulated arc therapy were included. One patient experienced ORN and required the extraction of teeth after RT. In the study approach, the dental arch curve (DAC) was defined using an open-source platform. Subsequently, pCT images and dose distributions were generated based on the new coordinate system. All teeth and mandibles were delineated on both the original CT and pCT images. To evaluate the consistency of dose metrics, the Mann-Whitney U test and Student t-test were employed. Results: A total of 61 teeth and 4 mandibles were evaluated. The correlation coefficient between the 2 methods was 0.999, and no statistically significant difference was observed (P>0.05). This method facilitated a straightforward and intuitive understanding of the delivered dose. In 1 patient, ORN corresponded to the region of the root and the gum receiving a high dosage (approximately 70 Gy). Conclusion: The proposed method particularly benefits dentists involved in the management of patients with HNC. It enables the visualization of a 3-dimensional dose distribution in the teeth and mandible on pCT, enhancing the understanding of the dose delivered during RT.