• The Journal of the Korean dental association
• /
• v.10 no.3
• /
• pp.155-158
• /
• 1972

As a factor of dentistry, the form of the tooth especially the size plays an important part. And in orthodontics the relation between the tooth size, arch length and the basal arch is regarded important, and it is closely related to the extraction and retension probolem in treatment planning. The auther's study of the mesio-distal crown diameters of permanent teeth, width and length of the dental arch and basal arch from the cast of 50 men and 53 women who could be measured clerly, among 102 men and 107 women regarded as the normal occlusion showed the followings. 1. Table 1 and table 2 showed the measurement of the mesio-distal maximum width of the permanent teeth, width and length of the dental arch and basal arch of the upper and lower dentitions. 2. Men's mesio-distal width of the teeth, arch length and arch width of the upper and the lower dentition, basal arch width and basal arch length are larger than those of wonen's 3. We compared the Koreans with the American white. Upper central incisors, upper first molars and lower second premolars of the latter were larger than those of the former. And the Koreans's rest tooth of the rest were comparatively larger.

• The Journal of Advanced Prosthodontics
• /
• v.9 no.2
• /
• pp.93-98
• /
• 2017

PURPOSE. The purpose of this study was to compare the width ratio of maxillary anterior teeth according to age in the Korean population and to evaluate the maxillary central incisor width-to-length (W/L) ratio, given differences in age and gender. MATERIALS AND METHODS. Ninety-three Korean adults were divided into 3 groups (n = 31) by age. Group I was 20 - 39 years old, Group II was 40 - 59 years old, and Group III was over 60 years of age. After taking an impression and a cast model of the maxillary arch, the anterior teeth width ratio and central incisor W/L ratio were calculated from standard digital images of the cast models using a graph paper with a digital single lens reflex (DSLR) camera. The calculated ratios were compared among all groups and central incisor W/L ratio were analyzed according to age and gender. All comparative data were statistically analyzed with one-sample t-tests, one-way ANOVAs with Tukey tests, and independent t-tests. RESULTS. No significant differences in maxillary anterior teeth ratios were found among the age groups. The maxillary central incisor W/L ratios in Group III were the greatest and were significantly higher than those in the other groups. The central incisor W/L ratio of men was higher than that of women in Group II. CONCLUSION. Maxillary anterior teeth width ratios were similar in all age groups in the Korean population. The maxillary central incisor was observed as worn teeth in the group over 60 years of age, and a significant difference between genders was found in 40 to 50 year olds.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.882-884
• /
• 2000

This paper deals with the effect of teeth width variation in Permanent Magnet DC motor. As teeth width varies, effective flux density is influenced, which is closely related to torque-speed characteristics, output power, and efficiency of the motor. In this study. motor design was carried out using finite element method with various teeth width. Prototype motors under constraints of same armature diameter, material and axial length were made and their performances were tested.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.2
• /
• pp.365-374
• /
• 1996

The prupose of this study was to obtain standard measurements of the tooth size, Bolton ratio, width and length of dental arch and basal arch, overbite and overjet of the children who have normal dentition. The plaster cast of 97 children(47 boys and 50 girls) among the contestants in 1992, 1994, 1995 Healthy Dentition contest in Seoul were measured and following results were obtained. 1. Means and standard deviations of the mesio-distal maximum width of the permanent teeth, Bolton ratio, width and length of the dental arch and basal arch of the upper and lower dentition and overbite and overjet of the children were obtained. 2. Mesio-distal width of the teeth, width and length of the dental arch and basal arch of the upper and lower dentition of the boys were larger than those of the girls. 3. Bolton Overall ratio, Anterior ratio and overjet of the boys were larger than those of the girls and overbite of the boys were smaller than those of the girls, but no significant differences were noted between the boys and the girls(p>0.05). 4. In the comparision of the Healthy Dentition Contestants with Korean adults of Shur, all teeth of the Contestants were larger than those of Korean adults, especially upper and lower bicuspids(p<0.01). In the comparision of the Healthy Dentition Contestants with Caucasians, all teeth except upper and lower central incisor and upper first molar of the contestants were larger than those of Caucasians(p<0.05).

• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.4
• /
• pp.533-541
• /
• 1993

This study was designed to help to be given esthetics in construction of denture and prosthodontic rehabilitation of anterior tooth region. The author took the facial straight photograph of 100 old aged people(male 50, female 50) above 55 years of age, who have natural teeth in anterior tooth region, in a resting and a smiling position. And the author measured and analyzed the lip shape, the relation between the lip and the teeth and the change of lip length and height when they were smiling. The results of this study were as follows : 1. In the shape of the upper lip, when the upper lip curved downward, it was 53%, straight was 28% and curved upward was 9%. 2. In the relation between the upper lip and the teeth, average smile was 53% , high smile was 26% and low smile was 21%. 3. In the parallel relation between the lower lip and maxillary anterior incisal curvature, the group of straight was 54%, the group of parallel was 40% and the group of reverse was 6%. 4. In the relationship between maxillary anterior incisor and lower lip, the group of not-touching was 92%, the group of touching was 5% and the group of the maxillary anterior incisor were slightly covered by the lower lip was 3%. 5. In the teeth displayed in a smile, displayed to second premolar was 50%, displayed to first molar was 34%, displayed to first premolar was 12%, and displayed to canine and second molar were 2%. 6. At smiling, the width of the mouth was 0.94 times of the interpupillary distance and 0.45 times of the full face width. 7. At smiling, the length of the upper lip was 0.73 times and lower lip was 0.98 times of the length in a resting postion and the width of the mouth corner was 1.19 times of the resting position.

• The Journal of Advanced Prosthodontics
• /
• v.4 no.1
• /
• pp.13-17
• /
• 2012

PURPOSE. We aimed to identify a more esthetic width-to-length ratio by analyzing maxillary central incisor of Korean adult population. Information regarding tooth ratio in the Korean population may be useful to clinicians when restoring anterior teeth. MATERIALS AND METHODS. A total of 40 men and 40 women were included in this study. The NON-MEDIA group included 40 non-celebrities, who were healthy and 25 to 39 years old, with normal dentofacial appearance. The MEDIA group consisted of 40 celebrities selected only on the basis of their soft-tissue facial appearance. The facial photographs of 40 celebrities were collected from the Internet websites. The width and length of the maxillary central incisor were measured using Adobe $Photoshop^{(R)}$ 7.0, a software for analysis, measurement and edition of photographs. Data were analyzed statistically using the Independent t-test at 5% statistical significance level. RESULTS. The mean ratio for the MEDIA group was 0.77, whereas that of the NON-MEDIA group was 0.88. The difference between the two groups was statistically significant. No significant gender differences were found in the width-to-length ratio in MEDIA group. In NON-MEDIA group, however, there were significant differences between female and male. CONCLUSION. After analyzing maxillary anterior teeth of Korean adults, our results were in accordance with the general Western standards of esthetics. A dentist restoring the natural look and beauty of teeth will have to consider those standards.

• Journal of Periodontal and Implant Science
• /
• v.34 no.1
• /
• pp.19-28
• /
• 2004

Tooth is the most important element in esthetic consideration on facial area. Tooth alignment which is in harmony with gingiva, lips, and face is also key element. The purpose of this study was to give a clinical discipline for restoration of gingival contour, which contains a ratio of maxillary 6 anterior teeth, research for gingival contour etc., in case of rehabilitation of maxillary anterior teeth. 300 Dankook university dental school students ,who is their twenties and free from periodontitis, participate in this study. The result was from each 70 males and females who had normal occlusion and tooth alignment. Length, width and length/width ratio of maxillary 6 anterior teeth were 0.74-0.81 in male, 0.81-0.84 in female. There was significant difference between male and female. The most deepest position of gingiva in maxillary central incisor and canine was located in distal part of teeth and maxillary lateral incisor was middle portion. In maxillary central incisors, gingival line of the most deepest point appeared significant difference between male and female (p<0.01) whereas there was no difference in lateral incisors and canines. Distance between interdental papilla apex and the most deepest portion appeared significant difference between male and female. Distance of the deepest position of gingiva is statistically significant except maxillary central incisors and lateral incisors. Standard deviation and mean of the width of labio-lingual were measured in cervical area and there was a significant difference both male and female.(p<0.01) From this result, we could get the mean of maxillary anterior gingival line and these results have great value in clinical guidance in studying maxillary anterior teeth.

• Restorative Dentistry and Endodontics
• /
• v.38 no.2
• /
• pp.59-64
• /
• 2013

Apical surgery cuts off the apical root and the crown-to-root ratio becomes unfavorable. Crown-to-root ratio has been applied to periodontally compromised teeth. Apical root resection is a different matter from periodontal bone loss. The purpose of this paper is to review the validity of crown-to-root ratio in the apically resected teeth. Most roots have conical shape and the root surface area of coronal part is wider than apical part of the same length. Therefore loss of alveolar bone support from apical resection is much less than its linear length.The maximum stress from mastication concentrates on the cervical area and the minimum stress was found on the apical 1/3 area. Therefore apical root resection is not so harmful as periodontal bone loss. Osteotomy for apical resection reduces longitudinal width of the buccal bone and increases the risk of endo-perio communication which leads to failure. Endodontic microsurgery is able to realize 0 degree or shallow bevel and precise length of root resection, and minimize the longitudinal width of osteotomy. The crown-to-root ratio is not valid in evaluating the prosthodontic prognosis of the apically resected teeth. Accurate execution of endodontic microsurgery to preserve the buccal bone is essential to avoid endo-perio communication.

• Journal of Veterinary Science
• /
• v.21 no.6
• /
• pp.83.1-83.14
• /
• 2020

Background: Bovine and porcine teeth are often used in in vitro experiments as substitutes of human teeth. Objectives: The aim of the present study was to perform a comparative analysis of enamel morphology of permanent human, bovine and porcine teeth under the scanning electron microscope. Methods: As many as 10 human, 10 bovine, and 10 porcine teeth were studied. All the teeth were sectioned and the halves were randomly divided into 2 groups according to the examined tissue (vestibular enamel at the mid-height of the dental crown and in the cervical area). Human and bovine enamel was etched for 15 sec and porcine enamel for 30 sec. The scanning electron microscope analysis was performed. The length and width of enamel prisms were determined with the "Met-Ilo" 1.1 computer program. Results: All enamel samples revealed the same etching pattern-Silverstone's type 2. Bovine enamel showed a similar porosity and the amount of interprismatic enamel compared to human enamel while the amount and width of interprismatic enamel bands in porcine enamel were evidently greater. The shape of the porcine prisms was visually similar to human prisms, although dimensions were significantly different. However, bovine prisms differed in form and appeared to be distinctly elongated. Conclusions: Reported findings indicate that the results of experimental studies carried out on bovine and porcine enamel should not be compared with the results obtained on human enamel.

• The Journal of Advanced Prosthodontics
• /
• v.9 no.4
• /
• pp.315-320
• /
• 2017

PURPOSE. The aim of this investigation was to analyze the dimensions of clinical crowns and to classify the crown and the gingival type in the anterior teeth in Korean young adults. MATERIALS AND METHODS. Casts were obtained from 50 subjects ranging in age from 24 to 32. Measurements of length and width were made on the casts using a pair of digital calipers on the entire dentition. Crown thickness and papilla height were also measured and MDW/CL (mesiodistal width to clinical length) and CW/CL (cervical width to clinical length) ratios of the maxillary anterior teeth were calculated. The K-clustering method was used for CW/CL to classify the anterior tooth shape into three groups (tapered, ovoid, and square), and one-way analysis of variance and Duncan's post-hoc comparison were used to evaluate statistical significance between the groups. Pearson's correlation analysis was performed between tooth shape and papillary height (PH) to demonstrate the correlation between tooth shape and gingival morphological characteristics. RESULTS. The average length of the maxillary central incisors was 9.89 mm; the mesio-distal width was 8.54 mm; and the ratio of width/length was 0.86 in Korean young adults. The average bucco-palatal thickness of the central incisor was 3.14 mm at the incisal 1/3 aspect. Ovoid type was the most common tooth shape (48%), followed by square type (29%) and taper type (23%) in the central incisors of Korean young adults. Tooth shape and gingival type were correlated with each other. CONCLUSION. New reference data were established for tooth size in Korean young adults and the data show several patterns of tooth shape and gingival type. Clinicians should diagnose and treat based on these characteristics for better results in the Korean population.