• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.214-218
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• 2009

The occlusal force of the tooth leads to loss of tooth tissue owing to attrition and abrasion, and may cause abfraction and pathological change of the dentin. Thus, we developed finite element models, examined them by applying ordinary occlusal force, and analyzed the stress distribution. Specimens used were mandibular first premolars from 15 Korean males and 13 females and were made into finite element models from medical images that were obtained using a Micro-CT. We have found that the irregular feature of the tooth is not only useful to masticating and pronouncing as well known, but it is also suitable for protecting inner tissue by dispersing stress and delivering proper pressure to periodontal tissue to continue a physiological action. Also, image analysis could let us know the factor that is the cause of a disorder due to stress concentration in the cervical line. These results are expected to support the field of dental treatment planning, operating procedure and clinical trial, and the advance of technical expertise to develop implants and dentures.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.3
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• pp.258-265
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• 2008

Purpose. This multicenter retrospective study was performed to evaluate the survival and success rates of immediate placement of USII and SSII Osstem implant (Osstem implant Co, Korea) on the maxillary and mandibular anterior and premolar areas. Materials and methods. Dental records were obtained in 37 patients who were treated with immediate implantation on the maxillary and mandibular anterior and premolar areas in 6 different clinics. The 98 implants were evaluated both clinically and radiographically using predefined success criteria. Results. There was no failed implant in all patients. The mean follow up period was 24.7 months (ranged from 12 to 58 months), and 25.1 months (ranged from 16 to 35 months) in USII and SSII implants, respectively. The crestal bone loss was 3 mm in 3 USII implants during 41 months, and in 1 SSII implant during 22 months. The overall success rate was 94.2% and 97.7% in USII and SSII implants, respectively. The age, gender, diameter, or length of implants, and type of surgery were not influenced to the success rate of immediate implantation. Conclusion. These results suggest that USII and SSII Osstem implant can be used successfully in immediate implantation on the maxillary and mandibular anterior and premolar areas.

• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.89-100
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• 1993

The purpose of this study was to evaluate the effect of orthodontic force on periodontal cellular activity by immunoperoxidase stain of epidermal growth factor, one of the tissue hormone. And supplementarily, to investigate of the changes of periodontal structures, periodontium was stained by H-E, Masson's Trichrome, P. A. S. stain after orthodontic force application. The experimental animals were four young adult dogs of average 8 month old. The fixed orthodontic appliance was cemented on mandibular right 4th premolar and 1st molar of each animal as experimental site. Mandibular left 4th premolar area of the same animal was used as control. The appliance consist of two silver crown soldered with 0.030' tube, $0.018\times0.022'$ S.S. sectional arch wire, and 0.009' open coil spring for manifestating of orthodontic force for bodily tooth movement of mandibular 4th premolar toward mesial direction. Experimental group was sacrificed at 1, 2, 3, 5 weeks from beginning of the experiment, and was investigated immunohistochemically and bistochemically by several staining methods. Findings were as follows: 1. The degree of EGF staining in control group was highest in epithelium of periodontium, and osteoclasts, osteoblasts and fibroblasts around the capillary were stained at higher level in periodontium. Generally, control group shows positive distribution of EGF all around the periodontal area. 2. The degree of EGF staining in control and 5 week group were similar, and did not show the significant different level between tension and pressure side. 3. All of 1, 2, 3 week group showed the same staining degree and distribution of EGF, and the tension side was more positive reaction of EGF stain than the pressure side. 4. The features of collagen fiber and periodontal fiber arrangement observed by H-E, Masson's Trichrome and P. A. S. stain revealed that oblique periodontal fibers were strectched in tension side, compressed in pressure side of all experimental group. Some fiber group in pressure side of 5 week group recovered the regular arrangement along the capillaries.

• The korean journal of orthodontics
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• v.42 no.5
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• pp.227-234
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• 2012

Objective: To evaluate the presurgical orthodontic tooth movement of mandibular teeth after dental decompensation for skeletal Class III deformities on the basis of vertical skeletal patterns. Methods: This cohort was comprised of 62 patients who received presurgical orthodontic treatment. These patients were divided into 3 groups according to their vertical skeletal patterns. Changes in the positions of the mandibular central incisor, canine, premolar, and 1st molar after presurgical orthodontic treatment were measured using a cone-beam computed tomography (CBCT) superimposition method. Results: The incisors moved forward after dental decompensation in all 3 groups. The canines in group I and the 1st premolars in groups I and III also moved forward. The incisors and canines were extruded in groups I and II. The 1st and 2nd premolars were also extruded in all groups. Vertical changes in the 1st premolars differed significantly between the groups. We also observed lateral movement of the canines in group III and of the 1st premolar, 2nd premolar, and 1st molar in all 3 groups (p < 0.05). Conclusions: Movement of the mandibular incisors and premolars resolved the dental compensation. The skeletal facial pattern did not affect the dental decompensation, except in the case of vertical changes of the 1st premolars.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.529-533
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• 2006

Supernumerary teeth are defined as an excess in the number of teeth when compared to the normal dental formula. They are more prevalent in the permanent dentition than the primary dentition. Supernumerary teeth can occur in the maxilla, mandible, or both. But the majority are found in the maxilla and most of it is found in the premaxilla region The present cases documents about the uncommon cases of supernumarary teeth on maxillarty premolar area and mandibular incisal area.

• Journal of Veterinary Science
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• v.21 no.5
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• pp.75.1-75.8
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• 2020

Background: Dental diseases are common in dogs and cats, and accurate measurements of dentoalveolar structure are important for planning of treatment. The information that the comparison computed tomography (CT) with dental radiography (DTR) is not yet reported in veterinary medicine. Objectives: The purpose of this study was to compare the DTR with CT of dentoalveolar structures in healthy dogs and cats, and to evaluate the CT images of 2 different slice thicknesses (0.5 and 1.0 mm). Methods: We included 6 dogs (2 Maltese and 1 Spitz, Beagle, Pomeranian, mixed, 1 to 8 years, 4 castrated males, and 2 spayed female) and 6 cats (6 domestic short hair, 8 months to 3 years, 4 castrated male, and 2 spayed female) in this study. We measured the pulp cavity to tooth width ratio (P/T ratio) and periodontal space of maxillary and mandibular canine teeth, maxillary fourth premolar, mandibular first molar, maxillary third premolar and mandibular fourth premolar. Results: P/T ratio and periodontal space in the overall dentition of both dogs and cats were smaller in DTR compared to CT. In addition, CT images at 1.0 mm slice thickness was generally measured to be greater than the images at 0.5 mm slice thickness. Conclusions: The results indicate that CT with thin slice thickness provides more accurate information on the dentoalveolar structures. Additional DTR, therefore, may not be required for evaluating dental structure in small-sized dogs and cats.

• The Journal of the Korean dental association
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• v.48 no.11
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• pp.819-828
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• 2010

Activator is a removable functional appliance used for correcting the skeletal Class II malocclusion in children with the mandibular deficiency. Berlin standard activator modified from Andresen activator has following characters; do not cover the palatal surface for tongue space, relief on lingual surface of mandibular incisors and resin capping 1/3-1/2 of crown height on mandibular incisors for preventing labioversion of mandibular incisors, L-hook between maxillary lateral incisor and canine for anterior high pull headgear, relief on mandibular posterior bite block for differential eruption of posterior teeth. Two cases presented here had a mandibular deficiency and slight maxillary protrusion. First case (an 11-year-old girl) treated with Berlin standard activator and anterior high pull headgear for 13 months followed by fixed orthodontic appliance for another 29 months. Second case (a 12-year-old boy) treated with Berlin standard activator for 6 months followed by fixed appliance for another 24 months. Treatment results showed a significant improvement in sagittal skeletal and occlusal relationship without premolar extraction. Mandibular condyles were concentric in TMJ [ossa, and masticatory muscle activities were normalized after treatment. In the retention period facial harmony and occlusal stability was maintained.

• The korean journal of orthodontics
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• v.48 no.3
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• pp.153-162
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• 2018

Objective: The aim of this trial was to compare the alignment efficiency and intermaxillary arch dimension changes of nickel-titanium (NiTi) or copper-nickel-titanium (CuNiTi) round archwires with increasing diameters applied sequentially to the mandibular arch. Methods: The initial alignment phase of fixed orthodontic treatment with NiTi or CuNiTi round archwires was studied in a randomly allocated sample of 66 patients. The NiTi group comprised 26 women, 10 men, and the CuNiTi ($27^{\circ}C$) group comprised 20 women, 10 men. The eligibility criteria were as follows: anterior mandibular crowding of minimum 6 mm according to Little's Irregularity Index (LII), treatment requiring no extraction of premolars, 12 to 18 years of age, permanent dentition, skeletal and dental Class I malocclusion. The main outcome measure was the alignment of the mandibular anterior dentition; the secondary outcome measure was the change in mandibular dental arch dimensions during 12 weeks. Simple randomization (allocation ratio 1:1) was used in this single-blind study. LII and mandibular arch dimensions were measured on three-dimensional digital dental models at 2-week intervals. Results: No statistically significant difference was observed between NiTi and CuNiTi according to LII (p > 0.05). Intercanine and intermolar arch perimeters increased in the CuNiTi group (p < 0.001). Inter-first premolar width showed a statistically significant interaction in week ${\times}$ diameter ${\times}$ application (p < 0.05). Conclusions: The effects of NiTi and CuNiTi round archwires were similar in terms of their alignment efficiency. However, the intercanine and intermolar arch perimeters, and the inter-first premolar width changes differed between groups.

• The korean journal of orthodontics
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• v.21 no.2 s.34
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• pp.341-351
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• 1991

Dental maturity is one of the index of physiological maturity indicators. To investigate the relationship between dental maturity and chronological age, the author took the orthopantomograms of 984 students, aged 7 through 17 years, having normal occlusion. The orthopantomograms were examined and calcification degree of each tooth on the left side was rated according to the method described by Demirjian. On the basis of findings of this study, the following results were obtained. 1. The root completion periods of mandibular permanent teeth were as follows; Central Incisor M $8.32{\pm}1.03\;years$ F $7.96{\pm}1.04\;years$ Lateral Incisor M $9.40{\pm}1.30\;years$ F $9.01{\pm}0.90\;years$ Canine M $12.81{\pm}1.24\;years$ F $11.42{\pm}0.94\;years$ 1st Premolar M $12.76{\pm}1.74\;years$ F $12.19{\pm}1.33\;years$ 2nd Premolar M $13.31{\pm}1.88\;years$ F $12.88{\pm}1.49\;years$ 1st Molar M $9.60{\pm}1.69\;years$ F $9.30{\pm}1.16\;years$ 2nd Molar M $14.38{\pm}1.73\;years$ F $13.96{\pm}1.63\;years$ 2. Sexual differences in same age group at given calcification stage were not significant statistically. 3. The developmental order in mandibular permanent teeth was as follows; a) central incisor, b) lateral incisor, c) 1st molar, d) canine and 1st premolar, e) 2nd premolar, f) 2nd molar.

• The Journal of Advanced Prosthodontics
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• v.7 no.1
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• pp.51-55
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• 2015

PURPOSE. Bone density at implant placement site is a key factor to obtain the primary stability of the fixture, which, in turn, is a prognostic factor for osseointegration and long-term success of an implant supported rehabilitation. Recently, an implant motor with a bone density measurement probe has been introduced. The aim of the present study was to test the objectiveness of the bone densities registered by the implant motor regardless of the operator performing them. MATERIALS AND METHODS. A total of 3704 bone density measurements, performed by means of the implant motor, were registered by 39 operators at different implant sites during routine activity. Bone density measurements were grouped according to their distribution across the jaws. Specifically, four different areas were distinguished: a pre-antral (between teeth from first right maxillary premolar to first left maxillary premolar) and a sub-antral (more distally) zone in the maxilla, and an interforaminal (between and including teeth from first left mandibular premolar to first right mandibular premolar) and a retroforaminal (more distally) zone in the lower one. A statistical comparison was performed to check the inter-operators variability of the collected data. RESULTS. The device produced consistent and operator-independent bone density values at each tooth position, showing a reliable bone-density measurement. CONCLUSION. The implant motor demonstrated to be a helpful tool to properly plan implant placement and loading irrespective of the operator using it.