• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.359-369
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• 2005

It has been suggested that morphologic characteristics of the periodontium are partly related to the shape and form of the teeth. Furthermore, the severity of symptoms of periodontal disease have been proposed to differ among these various morphologic entities or "biotypes". The purpose of the present study was to examine the relationship between the form of the crowns in the maxillary anterior tooth segment and (1) a group of morphological characteristics and (2) the thickness of the gingiva. The thickness of gingiva was measured by ultrasonic device(SDM). 100 subjects devoid of symptoms of destructive periodontal disease were examined regarding, e.g., probing depth, gingival recession, width of keratinized gingiva, thickness of the keratinized gingiva. From maxillary study cast, the width(at the apical third-CW) and the length(CL) of the crowns of the 6 anterior teeth were determined. A CW/CL-ratio was calculated for each tooth and averaged for each tooth region. The individual mean CW/CL-ratio values for the central incisors were ranked. The 10 subjects ranked highest and the 10 ranked lowest were selected as having either a long-narrow(group N) or a short-wide(group W) form of the crown of the tooth. The data for each of the examined parameters were averaged for each tooth region in each subject and mean values for subjects in groups W and N were compared using the Student t-test. Stepwise multiple regression analysis, including data from the whole sample, was performed for each tooth region with the thickness of the free gingiva as the dependent variable. The results from the analyses demonstrated that individuals with a long-narrow form of the central incisors displayed, compared to individuals with a short-wide crown, form (l) a narrow zone of keratinized gingiva, (2) a pronounced "scalloped" contour of the gingival margin. There was no significant difference between groups N and W with respect to the thickness of the keratinized gingiva. The CW/CL-ratio data revealed that a certain form of the crowns in the central incisors was accompanied by a similar form in the lateral incisors and canine tooth region. The regression analyses demonstrated that the thickness of the keratinized gingiva in central, lateral incisors and canines was significantly related to the width of the keratinized gingiva.

• The Journal of the Korean dental association
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• v.18 no.8 s.137
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• pp.639-644
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• 1980

In cases with maxillary lateral incisor missing, the problems were usually treated by the choice between space opening for prosthetic lateral incisor replacement and space closure with cuspid sub stitution for the alteral insicors. The decision of the choice could be perplexing in evaluation of the individual case. Therefore, various diagnostic criteria, such as occlusion, dental esthetics, canine position and inclination, tooth size relationship, maxillary lip length, and skeletal relation had to be evaluated. On the basis of this diagnostic information, the treatment planning could be established. A case was shown to illustrate the treatment of patient with congenitally maxillary lateral incisor missing.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.169-178
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• 2007

Dental crowding is one of the most common type of malocclusions in the mixed dentition. During the period of transition from the primary to the permanent dentition, minor incisor crowding is often present in the normally developing dentitions, but severe crowding can be caused by arch length/tooth size discrepancy. To determine the need for and appropriate timing of treatment for arch-length discrepancies, clinicians must be knowledgeable about normal development. This paper reviewed the literature on normal dental arch development and proper management of dental crowding according to its severity. Due to variations in the timing and the sequence of permanent tooth eruption, management of dental crowding should be specific to the individual patient.

• The Journal of Korean Academy of Prosthodontics
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• v.16 no.1
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• pp.27-31
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• 1978

A total of 200 patients, ranging in age from 20 to 60 years, were selected for the study. Each had at least one tooth which was restored with complete cast gold crown and a nonrestored contralateral tooth with no clinical evidence of caries and periodontal disease. The gingival tissues adjacent to the crowned and nonrestored teeth were examined to determine the evaluation of the severity of inflammation and probed to determine individual pocket depth. The findings are listed here. 1. The average sulcus bleeding index of the gingival tissues adjacent to crowned teeth was 1.99. The average sulcus bleeding index of the gingival tissues adjacent to nonrestored teeth was 0.67. 2. The average gingival sulcus depth adjacent to crowned teeth was 2.19mm. The average gingival sulcus depth adjacent to non restored teeth was 1.68mm. 3. No difference could be found between the average gingival sulcus bleeding index and average gingival sulcus depth of male and those of female. 4. The difference between sulcus bleeding index of the gingival tissues adjacent to crowned teeth and sulcus bleeding index of the gingival tissues adjacent to nonrestored teeth increased with increased age of the cast crown.

• Journal of the Korean Society of Radiology
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• v.7 no.4
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• pp.301-305
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• 2013

This thesis intends to analyze tooth distortion by mandibular arch form by reproducing existing panorama image and reconstructed panorama image of Cone Beam CT data with the three-dimensional computer program. The diameter of tooth measured in Cone Beam CT's cross-section image and reconstructed panorama was synchronized without any big change from incisors to posteriors. But, panorama showed serious distortion as going to posteriors after showing a little distortion in incisors. The panorama reconstructed for patients' individual arch showed reduced distortion than panoramas used generally. In addition, panorama showed serious distortion from incisors to posteriors and it means that distortion is reduced in reconstructed panorama.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.367-375
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• 1991

The clinical and radiographic features of 1,171 mesiodenses were studied with periapical radiograms and/or pantomograms in 942 persons visited the Department of Oral Radiology, School of Dentistry, Kyung Hee University during January 1980 to December 1989. The obrained results were as follows; 1. The incidence of mesiodens was higher in males (75.4%) than in females (24.6%). 2. In number of mesiodenses per individual, a single mesiodens was found to be 75.9%, 2-mesiodenses to be 23.8%, and 3-mesiodenses to be 0.2%. 3. In mesiodenses according to erupted and impacted status, the erupted mesiodens was found to be 16.5%, the impacted mesiodens in the interdental alveolar bone to be 66.6%, and in the region below root apex to be 16.9%. 4. In impacted mesiodenses according to direction of tooth crown, the inverted impaction was found to be 68.8%, the vertical impaction to be 15.1%, and the angulated impaction to be 16.1%. Among the impacted mesiodenses, a palatally located impaction was 87.5%, a middle 4.9%, and a labially 7.6%. 5. In mesiodenses according to shape of the tooth crown, a incisor-like type was found to be 1.6%, a canine-like type to be 6.8%, a conical type to be 79.2%, and a tuberculated type to e 12.4%. 6. In effect of mesiodens on adjacent tooth, non-specific influences were found to be 73.4%, crowding to be 0.3%, diastema to be 11.8%, rotation to be 5.7%, delayed eruption to be 3.8%, root resorption to be 2.6%, and dentigerous cyst to be 2.4%.

• Journal of Technologic Dentistry
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• v.42 no.3
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• pp.220-227
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• 2020

Purpose: This study aims to investigate the cusp variation pattern of the Korean mandibular second premolar and to determine the difference in tooth diameter and surface area using a virtual three-dimensional model. Methods: Dental casts from 69 students were scanned as a virtual dental models with a three-dimensional dental model scanner. Tooth diameter, absolute and relative individual areas, total crown area, the number of lingual cusps and central groove pattern were analyzed using RapidForm 2004. The Mann-Whitney U-test and the Kruskal-Wallis test were performed to verify sexual dimorphism, the difference in tooth diameter and surface according to the cusp variation pattern (α=0.05). Results: There was no significant difference except in buccolingual diameter (p<0.05) and buccolingual diameter at the cervix (p<0.05). The relative surface area of the total clinical crown was 65.76% for the buccal half and 34.24% for the lingual half, with a ratio of 2:1. In the case of the presence of two lingual cusps, the ratio was 21.47% for the mesiolingual half and 14.12% for the distaolingual half, with a ratio of 3:2. The dominant central groove patterns of the second premolar were the H-pattern (42.0%), followed by the Y-pattern (37.7%), then the U-pattern (20.3%). The relative buccal half was largest in the U-pattern central groove and the relative lingual half was largest in the Y-pattern central groove (p<0.05). Conclusion: This study is significant in that it measured quantitative surface areas and the findings could be a meaningful reference to comprehend dental anatomy in Koreans.

• Journal of the korean academy of Pediatric Dentistry
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• v.1 no.1
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• pp.57-61
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• 1974

The Study reported here was designed to analyze the prevalence of Dental Caries in the primary teeth of monozygote twins, and to ascertain and compare the intrapair differences with the intrapair differences in control pairs. The prevalence of dental caries in the primary teeth of 40 pairs of presumably monozygote twins, based on phenotypic analysis, was studied. The age range was from 3 to12 years. The control group consisted of pairs that included a twin chosen at random and an unrelated child of the same sex and age, so that for each pair of twins there was a corresponding control pair. The clinical examination was carried out by an operator using an oral mirror and sharp explorers, and with good lighting. 40 pairs of twins were examined with a total of 4,950 primary tooth surfaces (990 primary teeth) and 40 control pairs with a total of 4,935 primary tooth surfaces (987 primary teeth). Five surfaces were considered for each tooth. After the def individual index was determined, the ratio between this index and the number of examined surfaces was established in each case, the cer (Caries experience rate) index. The def and cer averages were determined for the subjects and the controls. All intrapair differences in twin and control groups were compared following the paired sampling method. The following conclusions were made: 1. Intrapair differences in the control group were significantly greater than in twins, when defs, ds, es, fs, and cer were compared. 2. The genotype appeared to be a determining factor in dental caries susceptibility or resistance, although the environment played an important role as well. 3. Intrapair differences in American children were significantly greater than in Korean when defs, es, fs, and cer were compared, but ds was equal.

• The Journal of Advanced Prosthodontics
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• v.11 no.3
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• pp.187-192
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• 2019

PURPOSE. The purpose of this in vitro study was to investigate the fracture loads and modes of failure for the full range of natural teeth under simulated occlusal loading. MATERIALS AND METHODS. One hundred and forty natural teeth were taken from mandibles and maxillas of patients. There were 14 groups of teeth with 10 teeth in each group (5 males and 5 females). Each specimen was embedded in resin and mounted on a positioning jig, with the long axis of the tooth at an inclined angle of 30 degrees. A universal testing machine was used to measure the compression load at which fracture of the tooth specimen occurred; loads were applied on the incisal edge and/or functional cusp. RESULTS. The mean fracture load for the mandibular first premolar was the highest (2002 N) of all the types of teeth, while the mean fracture load for the maxillary first premolar was the lowest (525 N). Mean fracture loads for the mandibular and maxillary incisors, and the first and second maxillary premolars, had significantly lower values compared to the other types of teeth. The mean fracture load for the teeth from males was significantly greater than that for the teeth from females. There was an inverse relationship between age and mean fracture load, in which older teeth had lower fracture loads compared to younger teeth. CONCLUSION. The mean fracture loads for natural teeth were significantly different, with dependence on tooth position and the sex and age of the individual.

• Journal of Oral Medicine and Pain
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• v.46 no.2
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• pp.21-32
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• 2021

Purpose: The purpose of the present study was to investigate the correlation between age and 34 radiomorphometric parameters on panoramic radiographs, and to provide generalized linear models (GLMs) as a non-invasive, inexpensive, and accurate method to the forensic judgement of living individual's age. Methods: The study included 417 digital panoramic radiographs of Korean individuals (178 males and 239 females, mean age: 32.57±17.81 years). Considering the skeletal differences between the sexes, GLMs were obtained separately according to sex, as well as across the total sample. For statistical analysis and to predict the accuracy of the new GLMs, root mean squared error (RMSE) and adjusted R-squared (R²) were calculated. Results: The adjusted R²-values of the developed GLMs in the total sample, and male and female groups were 0.623, 0.637, and 0.660, respectively (p<0.001), while the allowable RMSE values were 8.80, 8.42, and 8.53 years, respectively. In the GLM of the total sample, the most influential predictor of greater age was decreased pulp area in the #36 first molar (beta=-26.52; p<0.01), followed by the presence of periodontitis (beta=10.24; p<0.01). In males, the most influential factor was the presence of periodontitis (beta=9.20; p<0.05), followed by the number of full veneer crowns (beta=2.19; p<0.001). In females, the most influential predictor was the presence of periodontitis (beta=18.10; p<0.001), followed by the tooth area of the #16 first molar (beta=-11.57; p<0.001). Conclusions: We established acceptable GLM for each sex and found out the predictors necessary to age estimation which can be easily found in panoramic radiographs. Our study provides reference that parameters such as the area of tooth and pulp, the number of teeth treated, and the presence of periodontitis should be considered in estimating age.