• The Journal of the Korean dental association
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• v.19 no.7 s.146
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• pp.635-639
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• 1981

• The Journal of the Korean dental association
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• v.51 no.5
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• pp.265-273
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• 2013

The insurance payment plan for dental implants in Korea has been criticized because the payment priority has not been properly established, and the benefits are concentrated among middle-class citizens. In the current study, the relationship between the oral health condition and socioeconomic status of the elderly was analyzed using data from the Korea National Health and Nutrition Examination Survey (KNHANES). This study aims to determine the reason underlying the criticism of the insurance payment plan. The subjects were >65-year-old individuals in the 2010 and 2011 database of KNHANES. Data from 2,812 subjects were analyzed. The socioeconomic status was determined based on edentulousness, molar tooth loss, and presence of 28 teeth. According to the analysis, the average income was 1,560,000 won for edentulous elderly, 1,811,000 won for elderly who had lost molar teeth, and 1,896,000 won for elderly with 28 teeth (p<0.05). In addition, elderly with a low education level demonstrated a poor oral health condition (p<0.001). In conclusion, the insurance plan currently under examination is not properly designed for economically impoverished elderly because the plan only covers 50% of the costs and is limited to implantation of molar teeth only. This plan will not provide practical benefits to elderly with a poor socioeconomic status; therefore, the insurance payment plan needs to be improved so that the appropriate beneficiaries can be targeted.

• Journal of Oral Medicine and Pain
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• v.13 no.1
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• pp.13-21
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• 1988

The author studied the vertical height of tooth crown and the amounts of alveolar bone resorption with age. All 84 subjects(44 male, 40female) who visited Dental hospital of Wonkwang University with no history of sever periodontal disease and no experience of periodontal surgery. 84 subject were divided into 3 groups by age, that is, group I(28-32yrs), group II(38-42yrs), and group III(48-52yrs). Informal radiogram with bite wing film(horizontal angulation : $0^{\circ}$, vertical angulation : $+5^{\circ}~+10^{\circ}$) were taken on premolar and molar area. The distances from cusp tip to cementoenamel junction (vertical height of tooth crown) and from cementoenamel junction alveolar crest(amount of alveolar bone resorption) were measured, and then recorded data from 946 teeth were statistically analysed. This study was undertaken to obtain the data for age estimation by the changes of tooth crown height and alveolar bone resorption in the point of forensic odontology. The obtained results were as follows : 1. The average crown height of mandibular right 1st. molar was 7.1mm in group I, 6.7mm in group II, and 6.6mm group III, and the average amount of alveolar bone resorption on mandibular right 1st. molar were 1.8mm in group I, 2.5mm in group II, and 3.0mm in group III. Ratio of tooth crown height to amount of alveolar bone resorption was 4.0:1 in groupI, 2.7:1 in group II, and 2.2:1 in group III, the ratio was decreased with age. 2. In comparison with upper teeth and lower teeth in ipsilateral side, the average value of tooth crown height and amount of alveolar bone resorption were slightly higher in upper arch than those in lower arch, but there was not a statistically significant difference. 3. The ratio of height of tooth crown to amount of alveolar bone resorption was decreased with age, and which depended mainly upon the change of amount of alveolar bone resorption rather than the change of tooth crown height.

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.214-218
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• 2016

PURPOSE. We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS. To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by $10-20^{\circ}$ on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (${\alpha}=.05$). RESULTS. The differences with regard to repeatability were 4.5, 2.7, and $3.1{\mu}m$ for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and $11.0{\mu}m$ indicating the poorest reproducibility for the molar (P=.007). CONCLUSION. Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.3
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• pp.431-443
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• 1994

As the dental arch is the curve connecting the cusp tip of tooth, the dental arch form, composing of the occlusion, is one the important factors of occlusal reconstruction. Many studies about the horizontal dental arch form have been reported, but until now, it is unclear to infer the position of the teeth in dental arch form, to evaluate the effect of the horizontal dental arch form on chewing movement. The purpose of this study is to make objective criteria to infer the position of the teeth in dental arch. In this study, 100 subjects with individdual normal occlusion were evaluated. By multiple regression analysis on the basis of the relation of the canine and the first molar, the positions of teeth in dental arch were inferred. According to buccolingual relationship of maxillary to mandibular posterior teeth, the dental arch forms were classified into five groups, i, e. the normal group, the group which the maxillary second molar positions buccal side, the group which the maxillary premolars position buccal side, the group which the maxillary premolar position lingual side. From the results, objective criterial to infer the positons of the first premolar, the second premolar, the second molar in dental arch were made.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.300-307
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• 2018

PURPOSE. To investigate the fatigue and fracture resistance of computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic molar crowns on dental implants and human teeth. MATERIALS AND METHODS. Molar crowns (n=48; n=8/group) were fabricated of a lithium-disilicate-strengthened lithium aluminosilicate glass ceramic (N). Surfaces were polished (P) or glazed (G). Crowns were tested on human teeth (T) and implant-abutment analogues (I) simulating a chairside (C, crown bonded to abutment) or labside (L, screw channel) procedure for implant groups. Polished/glazed lithium disilicate (E) crowns (n=16) served as reference. Combined thermal cycling and mechanical loading (TC: $3000{\times}5^{\circ}C/3000{\times}55^{\circ}C$; ML: $1.2{\time}10^6$ cycles, 50 N) with antagonistic human molars (groups T) and steatite spheres (groups I) was performed under a chewing simulator. TCML crowns were then analyzed for failures (optical microscopy, SEM) and fracture force was determined. Data were statistically analyzed (Kolmogorow-Smirnov, one-way-ANOVA, post-hoc Bonferroni, ${\alpha}=.05$). RESULTS. All crowns survived TCML and showed small traces of wear. In human teeth groups, fracture forces of N crowns varied between $1214{\pm}293N$ (NPT) and $1324{\pm}498N$ (NGT), differing significantly ($P{\leq}.003$) from the polished reference EPT ($2044{\pm}302N$). Fracture forces in implant groups varied between $934{\pm}154N$ (NGI_L) and $1782{\pm}153N$ (NPI_C), providing higher values for the respective chairside crowns. Differences between polishing and glazing were not significant ($P{\geq}.066$) between crowns of identical materials and abutment support. CONCLUSION. Fracture resistance was influenced by the ceramic material, and partly by the tooth or implant situation and the clinical procedure (chairside/labside). Type of surface finish (polishing/glazing) had no significant influence. Clinical survival of the new glass ceramic may be comparable to lithium disilicate.

• Journal of Korean Dental Science
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• v.7 no.2
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• pp.66-79
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• 2014

Purpose: To analyze the amount and pattern of tooth movement and the changes in arch dimension of mandibular dentition after orthodontic treatment using a new three-dimensional (3D)-indirect superimposition method. Materials and Methods: The samples consisted of fifteen adult patients with class I bialveolar protrusion and minimal anterior crowding, treated by extraction of four first premolars with conventional sliding mechanics. After superimposition of 3D-virtual maxillary models before and after treatment using best-fit method, 3D-virtual mandibular model at each stage was placed into a common coordinate of superimposition using 3D-bite information, which resulted in 3D-indirect superimposition for mandibular dentition. The changes in mandibular dental and arch dimensional variables were measured with Rapidform 2006 (INUS Technology). Paired t-test was used for statistical analysis. Result: The anterior teeth moved backward, displaced laterally, and inclined lingually. The posterior teeth showed statistically significant contraction toward midsagittal plane. The amounts of backward movement of anterior teeth and forward movement of posterior teeth showed a ratio of 6 : 1. Although the inter-canine width increased slightly (0.8 mm, P<0.05), the inter-second premolar, inter-first molar, and inter-second molar widths decreased significantly with similar amounts (2.2 mm, P<0.05; 2.3 mm, P<0.01; 2.3 mm, P<0.001). The molar depth decreased (6.7 mm, P<0.001) but canine depth did not change. Conclusion: A new 3D-indirect superimposition of the mandibular dentitions using best-fit method and 3D-bite information can present a guideline for virtual treatment planning in terms of tooth position and arch dimension.

• Journal of Periodontal and Implant Science
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• v.39 no.4
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• pp.431-435
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• 2009

Purpose: The purpose of this study is to evaluate the long term clinical and radiographic outcome and stability after transplantation of third molar with complete root formation. Methods: The subjects were 31 teeth (male 17, female 14, aged 22-55, average 39.9 yr old) of 31 patients who visited the department of periodontics and passed more than two years after autotransplantation procedure and still under regular check up. Modified success criteria of Chamberlin and Goerig was applied to determine the success of autotransplantation. Results: Three out of 31 teeth failed and resulted 90.3% of success rate. When compared according to sex, 15 out of 17 teeth had succeeded in male, 13 out of 14 succeeded in female. When compared the success rate according to cause of extraction, tooth loss due to caries and root fracture had all succeeded but 3 out of 24 had failed in tooth loss due to periodontal disease. When compared according to donor teeth, 12 out of 14 maxillary third molars and 16 out of 17 mandibular third molars had succeeded. Conclusions: In long term evaluation over two years, if appropriate surgical procedure and proper case selection is made, autotransplantation of the third molar with complete root formation can be the alternative choice that substitutes prosthetic or implant treatment and it is a functionally acceptable procedure.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.2 no.1
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• pp.37-39
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• 1972

The author has observed on the impacted teeth of 11 cases from 484 full-mouth roentgenograms of dental students S. N. U. (except 3rd molar) These studies are very significant in oral surgery and orthodontic problems. Most of the impacted teeth are located in maxilla and among them 7 cases are impacted central incisors the others are lateral incisors, and cuspids. The form of impactions are vertical, horizontal and inverted positions.

• Journal of Periodontal and Implant Science
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• v.36 no.4
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• pp.809-816
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• 2006

Periodontal disease accompany the inflammation around periodontal tissue and generally periodontal destruction is followed, This destruction often makes the molar teeth have furcation defect. And to treat molar furcation involvement, resective surgery such as root resection and ostectomy and regenerative procedure such as guided tissue regeneration were introduced. Also implant can be considered as one of the good treatment methods, Among these treatment alternatives, root resection can be considered as a good procedure in the point of saving one's natural teeth or amount of cost. Therefore the purpose of this article is to evaluate root-resected teeth which were done at least 2 years ago. 70 root-resected teeth in 58 patient who visited Kyungpook National University Hospital were included in this study. They were evaluated by two clinical method. One is subjective evaluation and another is objective evaluation. To evaluate subjective outcome, 58 patients answered to the questionnaire if they experienced tooth extraction, bleeding, swelling, pain, mobility and chewing problem. To evaluate objective outcome, 28 teeth was evaluated according to Langer's criteria. The subjective result showed 82% of success rate and 18% of failure rate. 13 of 70 teeth showed discomfort and were considered as failure, which include chewing problem (39%) and pain (23%). The objective outcome showed that 4 failure (14% failure rate) which were 2 cases of bone loss by periodontal problem, one endodontic problem and one untreatable caries. By these limited results, some of clinical consideration in root resective procedure can be suggested. Periodontal support and less occlusal loading on resected tooth should be evaluated before the procedure, moreover, good oral hygiene is essential. When these factors are considered carefully, the root resection may produce predictive outcomes in the treatment of furcational involvement.