Analysis of dimensions and shapes of maxillary and mandibular dental arch in Korean young adults

PURPOSE: The aim of this study was to investigate dental arch dimensions and to classify arch shape in Korean young adults. MATERIALS AND METHODS: The sample included 50 Koreans with age ranging from 24 to 32 years. Maxillary and mandibular casts were fabricated using irreversible hydrocolloid and type III dental stones. Incisor-canine distance, incisor-1(st) molar distance, incisor-2(nd) molar distance, intercanine distance, inter-1(st) molar distance, and inter-2(nd) molar distance in both the maxillary and mandibular arch were measured using a three-dimensional measuring device. The dental arch was classified into three groups using five ratios from the measured values by the K-means clustering method. The data were analyzed with one-way analysis of variance. RESULTS: Arch lengths (IM2D, incisal-2(nd) molar distance) were 44.13 mm in the maxilla and 40.40 mm in the mandible. Arch widths (M2W, inter 2(nd) molar width) were 64.12 mm in the maxilla and 56.37 mm in the mandible. Distribution of the dental arch form was mostly ovoid shape (maxilla 52% and mandible 56%), followed by the V-shape and the U-shape. The arch width for the U-shape was broader than for the other forms. CONCLUSION: This study establishes new reference data for dental arch dimensions for young Korean adults. The most common arch form is the ovoid type in the maxilla and mandible of Koreans. Clinicians should be aware of these references and classify arch type before and during their dental treatment for effective and harmonized results in Koreans.

The effect of dental arch on dental panoramic radiography / 中国医学装备

Through the analysis on principles of dental panoramic radiography, we analyzed the influence factors of the dental arch, and provided the main principles for optimizing design to improve the image quality. Through the analysis on the human dental arch’s form, we optimized the radiographic procedure. Many factors affect the quality panoramic image, but the focal trough’s design is one of the most important factors, especially for canine regions. Optimizing design of focal trough can lessen degrees of horizontal and vertical magnification, also can reduce geometric distortion and overlapped images of teeth.

Comparison between dental and basal arch forms in normal occlusion and Class III malocclusions utilizing cone-beam computed tomography / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to investigate the relationship between the mandibular dental and basal arch forms in subjects with normal occlusion and compare them with those of Class III malocclusion using cone-beam computed tomography (CBCT). METHODS: CBCT images of 32 normal occlusion (19 males, 13 females; 24.3 years) and 33 Class III malocclusion subjects (20 males, 13 females, 22.2 years) were selected. Facial axis and root center points were identified from the left to right mandibular first molars. Distances between the facial axis and root center points for each tooth were calculated, and 4 linear and 2 ratio variables were measured and calculated for each arch form. The variables were compared between groups by independent t-test. Pearson correlation coefficient was applied to assess the relationships between dental and basal variables within each group. RESULTS: The mandibular dental and basal intercanine widths were significantly greater in the Class III group than in normal occlusion subjects (p < 0.05). The dental and basal intercanine widths as well as the dental and basal intermolar widths were strongly correlated in normal occlusion and moderately correlated in Class III malocclusion. CONCLUSIONS: The dental arch form demon strated a strong positive correlation with the basal arch form in the normal occlusion group and moderate correlation in the Class III malocclusion group. These results might be helpful for clinicians to have a better understanding of the importance of basal arch form in the alveolar bone.

Comparison of arch forms between Korean and Japanese in Class I, II, and III malocclusion / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare arch dimensions and frequency distribution of arch forms between Korean and Japanese Class I, II, and III malocclusion groups. METHODS: The sample consisted of 368 Korean cases (114 Class I, 119 Class II, and 135 Class III malocclusion) and 160 Japanese cases (60 Class I, 50 Class II, and 50 Class III malocclusion). The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket slot points were calculated for each tooth based on mandibular tooth thickness data. Four linear and two proportional measurements were taken. Measurements are statistically analyzed in each malocclusion group. The dental arches were classified into square, ovoid, and tapered forms to determine and compare the frequency distributions between the two ethnic groups. RESULTS: The findings of this study showed that Japanese females in Class I and II groups had a statistically significant narrower mandibular dental arch width compared with the Japanese males, Korean males and Korean females. But in the Class III group, there was no significant difference in the mandibular dental arch size according to the two ethnic groups and genders. CONCLUSIONS: The majority of Koreans and Japanese in all the malocclusion groups exhibited square and ovoid arch forms. The most frequent arch forms found in Koreans was square but ovoid for Japanese.

Size and forms of the mandibular dental arch in Korean malocclusion patients / 대한치과교정학회지

The purpose of this study was to clarify morphological differences among mandibular dental arch forms in Korean malocclusion patients. The sample in this study consisted of 114 Class I, 119 Class II, and 135 Class III malocclusion cases. The most facial portions of 13 proximal contact areas were digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth based on the data of the mandibular tooth thickness. Four linear and two proportional measurements were undertaken. The dental arches were classified into square, ovoid, and tapered forms to compare the frequency distributions. Our results suggested that there was no single arch form specific to any particular Angle classification or sex. It appeared to be the frequency of a particular arch form that varies among the Angle classifications. In comparison of arch measurements between male and female, there was no statistical difference except in the intermolar width. In comparison of arch size measurements among the different Angle classifications, there were statistically significant differences between Class I and Class III malocclusion groups and between Class II and Class III malocclusion groups. In comparison of frequency distribution of arch forms in Class I and III malocclusion groups, the square form demonstrated the highest distribution followed by the ovoid and tapered forms in that order. In the Class II malocclusion group, the square form showed the highest distribution, followed by the tapered and ovoid forms in that order. There was no statistical difference in the frequency distribution of arch forms between male and female groups.

The new approach to maxillary and mandibular anterior dental arch forms: The prediction to maxillary and mandibular anterior occlusal relationship by computer program / 대한치과교정학회지

When we deal with maxillary and mandibular anterior dental arches showing problems in occlusal relation and aesthetics caused by malformations of teeth and congenital missing, et al during the orthodontic treatment, we could not often decide the functional occlusion by only relying on the orthodontic treatment. If orthodontists can predict what kinds of treatments are needed for functional occlusion in maxillary and mandibular anterior dental arches, they can not only effectively treat patients but also facilitate the cooperation with other field during the treatment. Our previous research showed the correlation among intercanine width, segment depth and arch perimeter by using the Korean normal occlusion model. At this time, we produced the computer application program by taking advantage of this correlation. And then, we applied this program to setting up the treatment plans for 2 patients with the damaged maxillary and mandibular dentures. With the help of this program, we could not only easily acquire the information about the change of variables required by treatment plans but also understand the change of the anterior dental occlusion corresponding to the change of each variables such as the intercanine width, segment depth and arch perimeter. Later, if we can have the information about the relationship between the change of the angle of incisors depending on facial types and arch forms and, in addition, can acquire the appropriate intercanine width, we can have the ability to produce the 3 dimensional occlusogram for the anterior dental arch forms.

The new approach to maxillary and mandibular anterior dental arch forms : In Korean normal occlusion models / 대한치과교정학회지

Maxillary and mandibular anterior dental arches often have the problems of occlusal relation and esthetics by malformations of teeth, congenital missing, et al. Though the clinician usually use the anterior ratio to overcome this problems, he has the limitation of a direct application this ratio to the prediction of anterior occlusal relationship by the change of anterior ratio as dental arch form, intercanine width, segment depth and arch perimeter. So this study examine maxillary and mandibular anterior dental arch forms by least square method using Korean normal occlusion models(man : 20 casts, woman : 20 casts). Maxillary and mandibular anterior dental arches of Korean normal occlusion models are curve fitted to polynomial function, beta function, hyperbolic cosine function in order. And this accuracy of curve fitting is constant regardless of man/woman and maxilla/mandible. The relationships between intercanine width, segment depth, and arch perimeter based on this curve fitted dental arch form are acquired. This relationships will give the prediction of anterior dental arch form and the information of more accurate anterior ratio according to intercanine width.

Difference in dental arch form between Angle Ⅱ division 1 and normal occlusion assessed by Euclidean distance matrix analysis / 实用口腔医学杂志

Objective: To evaluate differences in dental arch forms between the subjects with Angle II division 1(AngleⅡ1 ) and those with normal occlusion. Methods:60 AngleⅡ1 patients and 60 normal occlusion subjects aged 13-17 years old were selected. Fourteen landmarks, corresponding to the cusp tips and incisor edges, were identified on the upper and lower dental casts of all subjects by YM-21115 three dimension measuring machine. Arch form differences between AngleⅡ1 and normal occlusion subjects were assessed by Euclidean distance matrix analysis (EDMA). Results:(1) In both sexes, the upper arch of AngleⅡ1 subjects was larger than that of normal occlusion (1.8% for females and 2.7% for males); and arch shape difference was also significantly different(P

A study of mandibular dental arch form of the Korean with normal occlusion / 대한치과교정학회지

The purpose of this study was to classify mandibular dental arch forms based on Raberin's method, and to compare Raberin's arch forms with that of the Korean's, and to designate arch form of bracket level according to distance between cusp tip and buccal surface of bracket level. The sample consisted of 159 mandibular dental casts showing normal occlusion which was taken from 62 males and 97 females of the Korean, aging from 13 to 25 years. The model was taken by X-ray. The landmarks were cusp points which expressed the mandibular dental arch line of cusp tips and buccal points which were measured from cusp tips to buccal surfaces of bracket level. The landmarks on the film were digitized, and measurements and statistics were performed. The results were as follows; 1. The models were classified as type I, type 2, type 3, type 4 and type 5 by the author, and polynomial functions of the six degree and R-square values were calculated using statistical method, and each calculated equations explained each group with the least R-square value of 0.97, and each arch forms were plotted. 2. The distribution of type I was 17.6 %, type 2 20.8%, type 3 20.8%, type 4 16.3% and type 5 24.5%. 3. The Korean arch form was characterized by larger width, smaller height compared to the French arch form. 4. The designated arch form of bracket level, viz the distance between cusp point and buccal point was calculated. The distance between cusp point and buccal point of incisor was 1mm, canine 1.9mm, first premolar 2.5mm, second premolar 2.6mm, first molar 2.7mm and second molar 2.7mm.