• Journal of Periodontal and Implant Science
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• v.47 no.5
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• pp.312-327
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• 2017

Purpose: This study assessed marginal bone remodeling and soft tissue esthetics after the loading of single bone-level implants in the anterior maxilla. Methods: An open, single-arm observational clinical trial with 3 years of follow-up was performed, including 22 implants. The patients presented with a single tooth gap in the anterior maxilla (tooth positions 14-24), with natural or restored adjacent teeth. An implant was placed at least 8 weeks post-extraction and healed submerged for 6 weeks. After the second-stage operation, a fixed provisional prosthesis was provided. The final restoration was placed 6 months after the provisional restoration. The time of the provisional crown connection was considered to be the baseline in this study. Esthetic parameters and the marginal bone level were assessed at 6, 12, 24, and 36 months. Results: All implants were well integrated in the bone. A statistically significant increase was found in the mean implant stability quotient between the time of the provisional prosthesis and the time of the final prosthesis. Most implants (95.5%) revealed marginal bone resorption (<0.5 mm), and just 1 implant (4.5%) showed a change of 2.12 mm from baseline to 36 months (mean $0.07{\pm}0.48mm$), while the crestal bone level decreased significantly, from $2.34{\pm}0.93mm$ at baseline to $1.70{\pm}1.10mm$ at 36 months. The facial gingival margin and papilla were stable and the esthetic scores indicated high patient and dentist satisfaction. Conclusions: Platform-switching bone-level implants placed in maxillary single-tooth gaps resulted in successful osseointegration with minimal marginal bone resorption. The peri-implant soft tissue was also esthetically satisfying and stable.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.293-297
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• 2009

Traumatic intrusion is a type of injury that involves axial displacement of a tooth toward the alveolar bone. Its occurance is relatively rare compared to other types of luxation in permanent dentition. It is more common in boys than in girls, and most common etiology of intrusion is fallen down. Various complication may occur following traumatic intrusion, such as pulp necrosis, root resorption, pulp obliteration and marginal bone loss. In addition, traumatic intrusion is commonly combined with hard or soft tissue injuries. Therefore, it is difficult to establish proper treatment plan. Choice of treatment for an intruded tooth by trauma include waiting for spontaneous re-eruption, orthodontic repositioning, and surgical repositioning. In this case, we repositioned the intruded central incisor using orthodontic traction, in a six-year old girl, which failed to re-erupt spontaneously.

• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.425-433
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• 1999

Dr. Youn-Sic Chun and coworkers invented the new machine for getting information about the relative effectiveness of the orthodontic appliances and we named it Calorific machine. The author and colleagues used this machine to compare with tooth moving mechanism by 3 types of the insertion method of precision-TPA for derotating the posterior teeth. We measured the distance of tooth movement and found out the rotational center on the occlusal X-ray film and the tooth movement on the occlusogram and then processed paired t-test by SAS program, The results were as follows : 1. In the intermolar width, the mesial insertion method showed the loss oi distance, and the other methods(-distal insertion method, mesial expansion method-) showed the increase of distance. 2. In the arch length, the distal insertion method was exhibited as most recommandable way for increasing the arch length .3. The rotation center of the mesial insertion method for derotating the molar, was located between mesial pit and central pit of the lower End molar. And, in the distal insertion method, it was located between distal pit and distolingual cusp, and in the mesial expansion method was located at distal pit.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.7 no.1
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• pp.25-28
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• 2011

Autism is a developmental, neuropsychiatric disorder that begins in early childhood. A patient with autism seen in the dental office frequently may have many complications. Therefore, it may be needed to consider modified or alternative therapy for dental care of autistic patients. This is the case of a 16-year old boy who have autism. He came to the department of the pediatric dentistry, Yonsei University Dental Hospital, for evaluation and treatment of dentigerous cyst associated with impacted teeth(#33,34,35). Under daily hospitalization and general anesthesia, the cyst was enucleated with surgical extraction of #34 and autotransplantation of #33,35. And during the periodic dental followup, apexification of #33,35 was performed for periapical lesion and root maturity. At 2 year 6 months follow- up, now, bony healing was completed and there are some complications like external resorption of #33 and space loss of #34 area. Generally, the marsupialization has been widely recommended for treatment of dentigerous cyst. However, in this case, there is a little possibility of spontaneous eruption after marsupialization considering of patient's age, location and angulation of the impacted tooth, root maturity. And there is necessity to choose the treatment that has low recurrence risk and needs short-term follow-up for autism. Above all, poor oral hygiene and lack of cooperation for decompression treatment is a matter of primary consideration. Consequently, enucleation of the cyst was chosen for the final treatment plan in this case. It is important to consider the conditions that affect the eruption of a dentigerous cyst-associated tooth to predict the successful eruption and special health care needs of the patient when the treatment plan is settled.

• The Journal of the Korea Contents Association
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• v.11 no.10
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• pp.370-379
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• 2011

This study was carried out in order to offer basic data available for forming the better oral health habit by closely examining a cause for industrial workers' tooth loss. It analyzed correlation in missing teeth with general characteristics, subjective oral health recognition, habit related to oral health, and oral symptom targeting 6,976 of production workers and office workers who work at 49 industrial places where are located in Gumi city of Gyeongsangbuk-do Province from June 1, 2009 to December 31, thereby having obtained the following conclusions. 1. The higher age group led to the higher ratio of missing teeth. The ratio of missing teeth was lower in a case of having been removed plaque than having not been removed plaque. 2. The ratio of missing teeth was high in a case of having dental caries and periodontal disease. The ratio of missing teeth was high in a case of having smoked in the past or in a case of smoking now. 3. The ratio of missing teeth was high in a case of having less toothbrushing frequency and in a case of not using dental floss or interdental brush. 4. The ratio of missing teeth was high when a tooth is throbbing and when tongue and cheek are throbbing in addition to pain and bleeding in gum. 5. The ratio of missing teeth was high in a case of having unpleasant bad breath. The above results are expected to be likely conducive to offering basic data necessary for developing the oral health educational program for industrial places that can promote and maintain workers' oral health, and for improving oral health program and system available for promoting and maintaining workers' oral health hereafter.

• Journal of Life Science
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• v.18 no.6
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• pp.764-769
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• 2008

Mutations in the human connexin 32 (Cx32) gene are responsible for X-linked Charcot-Marie-Tooth (CMTX) disease. Although over 300 different mutations have been identified the detailed molecular etiology of CMTX disease is poorly understood. Several studies reported that connexin membrane channels share most biophysical properties with their parental gap junction channels. In this study, two connexin mutant membrane channels (one mutant channel called the M34T channel in which the methionine residue at the $34^{th}$ position of the Cx32 protein is replaced with threonine residue and the other mutant channel called the T86C channel in which the threonine residue at the $86^{th}$ position is replaced with cysteine residue) associated with CMTX mutations were characterized at the single-channel level instead of using mutant gap junction channels. The biophysical properties of the M34T channel were very similar to those of the gap junction channel formed by M34T mutation. In addition, the mutant membrane channel study revealed the reversal of the gating polarity, the loss of fast gating and the gain of slow gating. The T86C channel also behaves like its parental wild type Cx32 membrane channel. Taken together, these results suggest that a study using connexin membrane channels is useful to characterize CMTX mutants.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.567-578
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• 2007

Statement of problem: The endodontically treated tooth is generally restored with post and core, owing to the brittle and the loss of large amount of tooth structure. As periodontal treatment was developed, there are many cases that periodontally involved teeth used in prosthetic treatment. Purpose: The purpose of this study was to analyze the stress distribution in the dentin and post structures by the various post materials and the amount of remaining alveolar bone height. Material and method: The 3-dimensional finite element models of mandible 1st premolars were divided into six types according to the various amount of remaining alveolar bone and post type. All types were modeled using equal length, diameter and shape of the post. Three types of post and core materials were used: prefabricated titaniumpost and amalgam core, prefabricated stainless steel post and amalgam core, and cast gold post and core. 300 Newton force was applied to functional cusp of mandible 1st premolar. Results: The results were as follows: First, there was no apparent difference in the pattern of stress distribution according to the alveolar bone condition concentrate on the post middle area. Second, there was difference in pattern of stress distribution according to the core materials, gold post and core generated same than amalgam core. Third, there was no apparent difference in the pattern of stress distribution within the dentin according to the post and core materials. But a cast gold post and core generated the lowest maximum stress value, a stainless steel post generated the highest maximum stress value. Fourth, in the reduced alveolar bone model, maximum stress value is 1.5 times than that of the normal alveolar bone model. Conclusion: Within the limitations of this study, to provide minimal stress to the root with alveolar bone reduced, the post length may be as long as apical seal was not destroyed. To prevent fracture of tooth, it is rational to use gold alloy which material was good for stress distribution for post materials.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.47-59
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• 2016

Purpose: The aim of this study was to investigate the changes in occlusal force after loss of the lower first molar depending on the inclination and extrusion of the adjacent and opposing teeth by using a strain gauge. Materials and Methods: Anatomic teeth were used to reconstruct the normal dental arch with loss of the lower right first molar. A uniformly thick layer of silicone was applied to the root to mimic the periodontal ligament. Four stages of dies with varying degrees of inclination and extrusion of the adjacent and opposing teeth were constructed and attached to master model interchangeably by using a CAD/CAM fabricated customized die system. The strain gauges were attached to teeth and a universal testing machine was used to determine the changes in occlusal force. An independent t-test and one-way ANOVA were performed (${\alpha}=.05$). Results: While simulating chewing food, the upper first, second premolar and lower second molar showed greater occlusal force than before extraction. When the change of adjacent teeth's occlusal force with their progressive movement after molar loss was evaluated, the difference among four die models was significant and was in the decreasing aspect (P < 0.05). Conclusion: When the lower first molar was lost and the adjacent teeth did not move yet, the occlusal force in adjacent teeth was higher than that when the lower first molar still existed. In addition, the occlusal force in the upper premolars and lower second molar decreased significantly with the progressive movement of adjacent teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.674-696
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• 1997

There're many cases that should be reconstructed with post and core when clinical crown is destructed. But this post and core restoration may cause damaging stress on the teeth. Previous finite element study was restricted to normal bone model relatively close to cemen-toenamel junction. Moreover, the test of a model with diminished bone support was rare. The purpose of this study is to test the effects of alveolar bone loss on the magnitude, stress distribution and displacement of post reconstructed teeth. In this study, it was assumed that the coronal portion of upper incisor was severely destructed. After conventional endodontic treatment, it was restored with post and core. The PFM restoration was made on it. This crown was cemented with ZPC. Alveolar bone was classified by 4 types of bone, such as normal, 2 mm, 4 mm, 6 mm bone, according to the bone loss. Meanwhile, the material of post are divided into 2 types of materials, such as gold, co-cr. Force was applied to two directions. One was fuctional maximum bite force (300 N) applied to the spot just lingual to the incisal edge with the angle of 45 degree to the long axis of the tooth, and the other one was horizontal force (300 N) applied to the labial surface. The results analyzed with three dimensional finite element method were as follows : 1. Stress was concentrated on the adjacent dentin of the post apex, one third portion of the post apex and the labial & lingual mid-portion of the root in all case. The stress of middle third of the root was apparently concentrated on the labial aspect. 2. The stress on adjacent dentin of the post apex and one third of the post apex increased as alveolar bone height moved apically. This increase was dramatic beyond 4 mm bone loss model. 3. The stress of the post apex was spreaded to the middle third of the post and greater than gold post in the case of metal post. 4. The displacement of the neck of post was the greatest in one of the post-cement interface and this increased as alveolar bone height moved apically. Besides the displacement of the metal post is slightly lower than one of the gold post.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.1-12
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• 2010

The aim of this study was to evaluate the preventive effect of commercially available anticariogenic products, specifically, the tooth cream containing Casein phosphopeptide-amorphous calcium phosphate(CPP-ACP), fluoride varnish and low-level fluoride mouthrinse on enamel erosion induced by carbonated beverage in a short period of time. Enamel specimens were treated as follows and were then kept in artificial saliva for 24 hours followed by further processing by alternately soaking them in Cola beverage and in distilled water for 1 minute each five times. Group 1: control group (no treatment) Group 2: tooth cream with CPP-ACP Group 3: fluoride varnish (1,000 ppm F) Group 4: low-level fluoride mouthrinse (227 ppm F) Group 5: fluoride varnish + tooth cream with CPP-ACP Group 6: low-level fluoride mouthrinse + tooth cream with CPP-ACP Microhardness and erosion depth were measured and the mineral loss of each specimen was evaluated by measuring the volumetric fluorescence change(${\Delta}Q$) against the stable fluorescent grid using quantitative light-induced fluorescence(QLF). The experiment lasted for 6 days repeated each day. The results were as follows: 1. The microhardness was increased as follows: Group $1{\leq}2{\leq}4$<6<$3{\fallingdotseq}5$. 2. The mean erosion depth was increased as follows: Group $5{\fallingdotseq}3$<6<$4{\fallingdotseq}2{\fallingdotseq}1$. 3. The ${\Delta}Q$ was increased as follows: Group $1{\fallingdotseq}2{\leq}4{\leq}6{\leq}3{\fallingdotseq}5$. The decrement of ${\Delta}Q$ was similar between group 1 and 2, group 4 and 6 and group 3 and 5. 4. The ${\Delta}Q$ showed positive correlation with microhardness (r=0.96, p<0.05), while it was negatively correlated to erosion depth (r=-0.96, p<0.05).