• The korean journal of orthodontics
• /
• v.15 no.1
• /
• pp.115-121
• /
• 1985

This study was intended to investigate the effect of mesiodistal crown widths of the anterior teeth on the incisor relationship and to determine whether incisor width ratio and anterior width ratio could be used to assess interarch tooth width harmony. From the casts taken from 63 subjects, 26 of open bite, 18 of deep bite and 19 of normal over bite with age of 17-20, mesiodistal crown widths of maxillary and mandibular 6 anterior teeth were measured with Boley gauge. On the basis of tooth measurements, anterior and incisor width ratio were calculated. The cephalograms were taken from same subjects to measure the degree of over bite and over jet and to compare the craniofacial bony structures between open bite, deep bite and normal over bite. Correlations among the anterior width ratio, incisor width ratio, over bite and over jet were calculated. The results were as follows. 1. There were no differences in mesiodistal widths of anterior teeth, incisor width ratio and anterior width ratio between open bite, deep bite and normal over bite. 2. The incisor width ratio and anterior width ratio can be useful in the assessment of tooth width harmony because the incisor width ratio and anterior width ratio were stable statistically and significantly correlated with each other. 3. Over bite and over jet were not correlated with incisor width ratio and anterior width ratio.

• The korean journal of orthodontics
• /
• v.25 no.5 s.52
• /
• pp.593-604
• /
• 1995

Mandibular incisor crowding is one of the most common features of malocclusion and is interesting characteristic in view of relapse and stability after orthodontic treatment. There are many potential factors in the etiology of lower anterior crowding. The tooth size variation is one of them, but biologic significance for the faciolingual width of the teeth has been overlooked. Peck and Peck reported that persons with ideal mandibular incisor alignment were shown to have incisor with smaller mesiodistal and larger faciolingual dimensions than persons with incisor crowding. On the basis of these findings they suggested MD/FL index as a clinical guideline for the assessment for lower incisor crowding. The present study was undertaken to examine the relationship between mandibular incisor crowding and mandibular incisor dimension, and determine their correlation with arch length discrepancy. 154 dental casts of people from 11 to 17 years of age were made, and were divided into normal group with irregularity index less than of 1, and crowding group with irregularity index greater than 1.The casts were measured and analyzed statistically. The results were as follows. 1. The mean mesiodistal width for mandibular incisor was larger in crowding group, and has significant difference in central inciosr measurement. There are no significant differences in the faciolingul width and MD/FL index. 2. Irregularity index has significant correlation coefficients with mesiodistal width and MD/FL index for mandibular incisor in crowding group, but no correlation with faciolingual width. It also has correlation with maxillary and mandibular arch length discrepancy, total tooth material, mandibular intercanine width, and mandibular inter first premolar width. 3. Upper and lower arch length discrepancy have significant correlation with mesiodistal width of mandibular incisor and overbite, but have no correlation with faciolingual width. Lower arch lenth discrepancy has significant correlation with MD/FL index for mandibular incisor and upper arch length discrepancy has correlation with MD/FL index for mandibular lateral incisor. 4. Significant differences were observed between normal and crowding group for the mandibular arch length discrepancy and overbite.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.2
• /
• pp.125-130
• /
• 2016

PURPOSE. The purpose of this study was to determine the effect of changes in the horizontal plane angle on the mesiodistal width ratios of the maxillary anterior teeth during the acquisition of frontal view photographs, derive these ratios for Korean adults on the basis of the data obtained, and analyze them using the Golden Proportion as a reference. MATERIALS AND METHODS. In experiment I, 30 plaster casts were mounted on an articulator and positioned on the angle-measuring device with a center setting of $0^{\circ}$. The device was rotated to $10^{\circ}$ in $1^{\circ}$ increments in a counterclockwise direction. At each angle, photographs were obtained and analyzed. Experiment II was based on 60 patients who visited the Department of Prosthodontics at Kyungpook National University Dental Hospital from February 2012 to February 2015. The patients were divided into three groups [Male (M), Female (F), Total (M + F)]. Frontal views were obtained for all groups and analyzed. RESULTS. From $1^{\circ}$ to $10^{\circ}$, the relative mesiodistal width ratios for the maxillary anterior teeth showed no significant differences from those at $0^{\circ}$. In all three groups, the relative width ratio of the maxillary central incisor was smaller than that specified in the Golden Proportion; the opposite was true for the canine. CONCLUSION. Our results suggest that the mesiodistal width ratios of the maxillary anterior teeth do not follow the Golden Proportion in Korean adults, and that a change in the horizontal plane angle from $1^{\circ}$ to $10^{\circ}$ during frontal photography does not affect these ratios.

• The korean journal of orthodontics
• /
• v.3 no.1
• /
• pp.7-13
• /
• 1972

Many geometric curves are presented as representative form of normal dental arches by many authors; circle, ellipse, parabola or catenary curve. Among them those except circle seems difficult to be adopted as a guide in ideal arch form construction and practically many orthodontists chose circle as a standard. Author preferred circle of Bonwill's theory in study of anterior teeth alignment of Korean adults. Eighty three dental models which possess proper occlusion and good arch form were selected and copies of their occlusal surfaces obtained by Ricopy machine. The use of Ricopy machine made it possible to draw arch form exactly. Mesiodistal widths of six anterior teeth were measured and they were added to combined mesiodistal width of six anterior teeth. Circle, that include the points of two cuspal tips of canines and one incisal edge of central incisor were drawn. Distances of lateral incisors that are deviated from arc of this circle were measured and classified into four grades by degree and three groups by kind of teeth deviated. By counting the number of samples involved degree of fit of the circle to arch contour of Korean adult was described. Then, size of radius of circle, intercanine width and intermolar width were measured and evaluated their ratios to combined mesiodistal width of six anterior teeth. In normal occlusion of Korean adult anterior teeth seems to be arranged on an arc of circle the radius of which is similar to combined mesiodistal width of six anterior teeth. Intercanine width and intermolar width have rather constant ratios to combined width of six anterior teeth.

• The Journal of Korean Academy of Prosthodontics
• /
• v.53 no.4
• /
• pp.310-317
• /
• 2015

Purpose: The purpose of this study was to evaluate the validity of reference points for edentulous patient by examining the correlation of teeth and face, and intraoral anatomic landmarks. Materials and methods: We examined a facial outline, length, bizygomatic width, nasion - gnathion length, glabella - nasion distance in 270 men and 280 women satisfied with inclusion criteria from Seoul National School of Dentistry. The shape of maxillary central incisor, mesiodistal crown width and length of maxillary 6 incisors, distance from incisive papilla to labial surface of maxillary central incisor, and perpendicular distance from incisive papilla to intercanine line were measured in the stone model. We analyzed the ratio and relevant relation statistically. Results: The probability on having the same shape of face and the relative same shape maxillary incisor was 55.56% and 46.43% for men and women. The facial length proved to be a more valuable measurement in women in the tooth selection. The ratio of bizygomatic width to mesiodistal width of maxillary central incisor, and the ratio of bizygomatic width to width of maxillary 6 incisors were 16.8 : 1 and 3.0 : 1 and were positively correlated with each other. The distance of the canines from the maxillary incisal papilla was $1.33{\pm}1.28mm$. The distance between the center of the incisal papilla and the labial surface of their maxillary central incisor was $9.23{\pm}1.20mm$. Conclusion: It was showed that anatomical reference points in tooth selection and arrangement for edentulous patient are useful and have validity in our limited study.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.3
• /
• pp.510-521
• /
• 2006

This investigation was undertaken to examine the extent to which tooth size and arch dimension each contribute to dental crowding. The sample included 50 subjects with well aligned dentition (25 males, 25 females) and those of 40 subjects with gross dental crowding(20 males, 20 females). Plaster model and digital model made from alginate impression taken at the one visit. Tooth size, arch length, arch perimeter, intercanine width and intermolar width was measured on the plaster and digital models. The findings in this study lead to the following conclusions. 1. In maxilla, the mesiodistal diameters of lateral incisor and premolars of the crowded group were significantly larger than those of the normal occlusion group (P<0.05). 2. In mandible, the mesiodistal diameters of central incisor, canine and premolars of crowded group were significantly larger than those of the normal occlusion group (P<0.05). 3. In maxilla, arch perimeter and intermolar width of crowded group were significantly smaller than normal occlusion group but intercanine width of crowded group were larger than normal occlusion group (P<0.05). There was no significantly difference in arch length (P>0.05). 4. In mandible, arch perimeter of crowded group was smaller than normal occlusion group(P<0.05). There were no difference in arch length intermolar width and intercanine width (P>0.05) 5. In the analysis of correlation coefficients of arch length discrepancy with variables, arch perimeter, intermolar width and mesiodistal width of 2nd premolar showed positive correlations in maxilla. 6. There was a significant difference between tooth width measurements made by the 2 methods, with all the digital model measurement larger than plaster model measurements (P<0.05) : the magnitude of the differences does not appear to be clinically relevant. 7. In the analysis for reproducibility, the plaster model measurement was showed lower degree of correlation between 1st and 2nd measurement than digital model.

• The korean journal of orthodontics
• /
• v.30 no.1 s.78
• /
• pp.115-126
• /
• 2000

Dental arch expansion is one of the method used to solve the dental crowding problem by non-extraction. Many formulae using tooth size have been suggested to predict ideal inter-premolar and inter-molar width. The purpose of this study was to evaluate the adequacy of some upper dental arch width prediction methods, namely Pont's method, Schmuth's method and Cha's method. The sample consisted of the casts of 119 Korean young adults who had no muscular abnormality, no skeletal discrepancy, and Angle's Class I molar relationships. Measurements were obtained directly from plaster casts; they Included mesiodistal crown diameters of the four maxillary incisors, as well as maxillary inter-first-premolar and inter-first-molar arch widths as specified by Pont. The correlation coefficients between the sum of incisors(SI) and upper dental arch width were calculated. The differences between predicted width and actual width were classified as overestimated, properestimated, and underestimated. The data obtained from each group were analyzed for statistical differences. The results were as follows : 1. Upper dental arch width indices were calculated from SI in normal occlusion (81.96 : premolar index, 62.55 : molar index). 2. Low correlations between SI and arch width were noted in normal occlusion (0.50 in the inter-premolar width, 0.39 in the inter-molar width). 3. Pont's formula and Schmuth's formula tended to overestimate the inter-premolar width. A more even distribution of estimates was noted in Cha's fomula. 4. Cases within $\pm$1 mm range of observed inter-premolar width were $45\%$ in the Cha's formula, $40\%$ in the Pont's formula, and $39\%$ in the Schmuth's formula. 5. All formulae had a tendency to underestimate the inter-molar width, but Cha's formula had better predictability than others. 6. Cases within $\pm$1 mm range of observed inter-molar width were $40\%$ in the Cha's formula, $29\%$ in the Pont's formula, and $13\%$ of Schmuth's formula. The data presented in this study does not support the clinical usefulness of ideal arch width prediction methods using the mesiodistal width of maxillary incisors.

• Journal of dental hygiene science
• /
• v.6 no.1
• /
• pp.29-34
• /
• 2006

This study was undertaken to compare the tooth and arch size between crowding patient and normal subjects. Two group of dental casts were selected on the basis of crowding patients and normal subjects. One group, consisting of 40 pair of dental casts(20 male and 20 female), exhibited noncrowded dentitions. A second group, consisting of 40 pairs of dental cast(21 male and 21 female), exhibited remarkably crowding need for orthodontic treatment. Tooth width measurements were made with a sliding digital caliper with Vernier scale neared 0.01 mm. Mean, standard deviation, T-test of the following parameters were used to compare two group : individual mesiodistal crown widths, arch width and arch length. The following result were obtained. In the mesiodistal crown widths, normal subjects had generalized larger teeth than Wheeler's results(human tooth size index), except for maxillary central incisor, maxillary 2nd premolar, mandibular canine, and mandibular 1st molar. In the orthodontic patients with crowded dentitions, the mesiodistal tooth crown widths were generalized larger teeth than noncrowded normal subjects. In the arch width and arch length, the crowded dentition group had smaller arch width and arch length than the normal group.

• 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.

• The korean journal of orthodontics
• /
• v.45 no.4
• /
• pp.190-197
• /
• 2015

Objective: The aim of the study was to analyze the prevalence and distribution of ectopic eruption of the permanent maxillary first molar (EEM) in individuals scheduled for orthodontic treatment and to investigate the association of EEM with dental characteristics, maxillary skeletal features, crowding, and other dental anomalies. Methods: A total of 1,317 individuals were included and randomly divided into two groups. The first 265 subjects were included as controls, while the remaining 1,052 subjects included the sample from which the final experimental EEM group was derived. The mesiodistal (M-D) crown width of the deciduous maxillary second molar and permanent maxillary first molar, maxillary arch length (A-PML), maxillomandibular transverse skeletal relationships (anterior and posterior transverse interarch discrepancies, ATID and PTID), maxillary and mandibular tooth crowding, and the presence of dental anomalies were recorded for each subject, and the statistical significance of differences in these parameters between the EEM and control groups was determined using independent sample t -tests. Chi-square tests were used to compare the prevalence of other dental anomalies between the two groups. Results: The prevalence of maxillary EEM was 2.5%. The M-D crown widths, ATID and PTID, and tooth crowding were significantly greater, while A-PML was significantly smaller, in the EEM group than in the control group. Only two subjects showed an association between EEM and maxillary lateral incisor anomalies, which included agenesis in one and microdontia in the other. Conclusions: EEM may be a risk factor for maxillary arch constriction and severe tooth crowding.