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.

Preliminary three-dimensional analysis of tooth movement and arch dimension change of the maxillary dentition in Class II division 1 malocclusion treated with first premolar extraction: conventional anchorage vs. mini-implant anchorage / 대한치과교정학회지

OBJECTIVE: This study aimed to compare the effects of conventional and orthodontic mini-implant (OMI) anchorage on tooth movement and arch-dimension changes in the maxillary dentition in Class II division 1 (CII div.1) patients. METHODS: CII div.1 patients treated with extraction of the maxillary first and mandibular second premolars and sliding mechanics were allotted to conventional anchorage group (CA, n = 12) or OMI anchorage group (OA, n = 12). Pre- and post-treatment three-dimensional virtual maxillary models were superimposed using the best-fit method. Linear, angular, and arch-dimension variables were measured with software program. Mann-Whitney U-test and Wilcoxon signed-rank test were performed for statistical analysis. RESULTS: Compared to the CA group, the OMI group showed more backward movement of the maxillary central and lateral incisors and canine (MXCI, MXLI, MXC, respectively; 1.6 mm, p < 0.001; 0.9 mm, p < 0.05; 1.2 mm, p < 0.001); more intrusion of the MXCI and MXC (1.3 mm, 0.5 mm, all p < 0.01); less forward movement of the maxillary second premolar, first, and second molars (MXP2, MXM1, MXM2, respectively; all 1.0 mm, all p < 0.05); less contraction of the MXP2 and MXM1 (0.7 mm, p < 0.05; 0.9 mm, p < 0.001); less mesial-in rotation of the MXM1 and MXM2 (2.6degrees, 2.5degrees, all p < 0.05); and less decrease of the inter-MXP2, MXM1, and MXM2 widths (1.8 mm, 1.5 mm, 2.0 mm, all p < 0.05). CONCLUSIONS: In treatment of CII div.1 malocclusion, OA provided better anchorage and less arch-dimension change in the maxillary posterior teeth than CA during en-masse retraction of the maxillary anterior teeth.

Comparison of arch form between ethnic Malays and Malaysian Aborigines in Peninsular Malaysia / 대한치과교정학회지

OBJECTIVE: To determine and compare the frequency distribution of various arch shapes in ethnic Malays and Malaysian Aborigines in Peninsular Malaysia and to investigate the morphological differences of arch form between these two ethnic groups. METHODS: We examined 120 ethnic Malay study models (60 maxillary, 60 mandibular) and 129 Malaysian Aboriginal study models (66 maxillary, 63 mandibular). We marked 18 buccal tips and incisor line angles on each model, and digitized them using 2-dimensional coordinate system. Dental arches were classified as square, ovoid, or tapered by printing the scanned images and superimposing Orthoform arch templates on them. RESULTS: The most common maxillary arch shape in both ethnic groups was ovoid, as was the most common mandibular arch shape among ethnic Malay females. The rarest arch shape was square. Chi-square tests, indicated that only the distribution of the mandibular arch shape was significantly different between groups (p = 0.040). However, when compared using independent t-tests, there was no difference in the mean value of arch width between groups. Arch shape distribution was not different between genders of either ethnic group, except for the mandibular arch of ethnic Malays. CONCLUSIONS: Ethnic Malays and Malaysian Aborigines have similar dental arch dimensions and shapes.

Comparison of arch form between Koreans and Egyptians / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate morphologic differences in the mandibular arch between Egyptian and Korean subjects. METHODS: The Egyptian sample consisted of 94 mandibular casts (35 Class I, 32 Class II and 27 Class III). The Korean sample consisted of 462 mandibular casts (114 Class I, 119 Class II, and 135 Class III). The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth. The subjects were grouped according to arch form to compare the frequency distribution of the 3 arch forms between the ethnic groups in each Angle classification. RESULTS: Egyptians had significantly narrower intermolar and intercanine widths (p < 0.001), and shallower intermolar and intercanine depths (p < 0.001) than Koreans. There was an even frequency distribution of the 3 arch forms within the Egyptian group (p = 0.46). However, in the Korean group, the most frequent arch form was the square arch form (46.7%), while the frequency of the tapered arch form was significantly lower (18.8%). CONCLUSIONS: These results might provide helpful information in evaluating morphologic differences between ethnic groups in selection of preformed superelastic archwires.

Spacing and crowding of the primary dentition in Korean children - relationship to tooth sizes and dental arch dimension / 대한치과교정학회지

The aims of this study were to investigate the prevalence of spaced, closed, and crowded primary dentitions by sex and arch in Korean children from Kanghwa, and to determine the frequency of the primate and developmental spaces. The differences in the mesiodistal crown diameters and the arch dimensions between the spaced, closed, and crowded primary dentitions were also evaluated. Dental casts of 102 preschool children (57 males and 45 females, aged 4 ~ 5 years) were studied. The prevalence of spacing in the primary dentition was 63.2% in males and 57.8% in females. The frequency of spacing was greater in males than in females, and greater in the maxillary arch than in the mandibular arch. The crowns were significantly larger and the arches significantly narrower in closed and crowded dentitions than in those with spacing (p < 0.05). The results showed that the prevalence of spacing was lower than that found in previous studies and the presence of spacing in the anterior region was related to the mesiodistal crown diameter and the intercanine width.

Craniofacial structure and arch dimension of adult Class III malocclusion / 대한치과교정학회지

This study was conducted to discern-differences of craniofacial, dentnalveolar structure and model measurements between sex and between class III openbite group and non-openbite group. The sample consisted of 49 adult patients with class III malocclusion. 24 linear measurements, 22 angular measurements and 12 ratios were -selected in lateral cephalometry. Also, arch width, length, antericr crowding, average molar relation were measured or calculated in diagnostic model. The data were evaluated by t-test and multiple discriminant analysis. The results were as follows ; 1. Most linear measurements, with the exception of MnBL and AUDH, were significantly larger in male(p0.05). but openbite group showed significantly increased gonial angle(p<0.05), FH-CoGo(p<0.01), FH-NA(p<0.01) and FH-NB, FH-NPog (p<0.05). 4. ALFH and PUDH were larger(p<0.05) in openbite group. this result served as compensation for the spatial position of mandible relative to cranial base. AUPUDH (p<0.001) and ALPLDH(p<0.05) were lower in openbite group. upper anterior crowding was the only measurement which showed difference between openbite and non-openbite group(p<0.05). 5. For the purpose of classifying adult class III openbite and non-openbite group, multiple discriminant analysis was done. gonial angle, ALPLDH, AUPUDH, FH-NA were included in multiple discrinunant equation. 39 cases(92.86%) were correctly classified when applied to the sample used in this study.

Effect of changes in the anterior arch dimension on precision of Bolton analysis / 实用口腔医学杂志

Objective:To investigate whether the changes of anterior arch dimension have an impact on the precision of Bolton analysis. Methods:A mathematic-geometric model was used to evaluate the data. Results:The ideal anterior tooth size ratio may need adjustments, depending on the dimensions in radii of the upper and lower anterior dental arches. The ideal ratio is lower for dental arches with a high anterior curvature. There is a deficiency in the upper arch, a flatter anterior segment may compensate for some of the discrepancy and vice versa. Conclusion:An ideal Bolton value may not guarantee an ideal occlusion. Anterior tooth size ratio is not precise in predicting the anterior inter relationship post-treatment.

A comparative study on dental arch dimension of high school females according to the region of residence and facial type / 대한치과교정학회지

This study was performed to compare the dental arch dimensions of urban and rural high school females according to the region of residence and facial type. A model and cephalometric analysis was made from 48 urban and 48 rural high school females. The results of this study were obtained as follows: 1. Arch width in the urban group were similar to the rural group. 2. Lingual arch length at upper 1st premolar level in the urban group was larger than the rural group and lingual arch length at lower canine level in rural group was larger than the urban group. 3. Palatal height at canine level in the rural group was higher than the urban group. 4. Palatal heights at 2nd premolar and 1st molar level had correlation with the VERT index. In comparison of lingual arch dimensions according to Rickett's facial group, palatal heights at 2nd premolar and 1st molar level in dolichofacial group were lower than other groups.