• Imaging Science in Dentistry
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• v.52 no.2
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• pp.197-207
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• 2022

Purpose: This study evaluated the associations of the dental arch form, age-sex groups, and sagittal root position (SRP) with alveolar bone thickness of the maxillary central incisors using cone-beam computed tomography (CBCT) images. Materials and Methods: CBCT images of 280 patients were categorized based on the dental arch form and age-sex groups. From these patients, 560 sagittal CBCT images of the maxillary central incisors were examined to measure the labial and palatal bone thickness at the apex level and the palatal bone at the mid-root level, according to the SRP classification. The chi-square test, Kruskal-Wallis test, and multiple linear regression were used for statistical analyses. Results: Significant differences were found in alveolar bone thickness depending on the arch form and SRP at the apex level. The square dental arch form and class I SRP showed the highest bone thickness at both levels of the palatal aspect. The taper dental arch form and class II SRP presented the highest bone thickness at the apex level of the labial aspect. No association was found between the dental arch form and SRP. Elderly women showed a significant association with thinner alveolar bone. Age-sex group, the dental arch form, and SRP had significant associations with alveolar bone thickness at the apex level. Conclusion: The patient's age-sex group, dental arch form, and SRP were associated with alveolar bone thickness around the maxillary central incisors with varying magnitudes. Therefore, clinicians should take these factors into account when planning immediate implant placement.

• The korean journal of orthodontics
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• v.45 no.2
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• pp.74-81
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• 2015

Objective: The purposes of this study were 1) to classify lingual dental arch form types based on the lingual bracket points and 2) to provide a new lingual arch form template based on this classification for clinical application through the analysis of three-dimensional virtual models of normal occlusion sample. Methods: Maxillary and mandibular casts of 115 young adults with normal occlusion were scanned in their occluded positions and lingual bracket points were digitized on the virtual models by using Rapidform 2006 software. Sixty-eight cases (dataset 1) were used in K-means cluster analysis to classify arch forms with intercanine, interpremolar and intermolar widths and width/depth ratios as determinants. The best-fit curves of the mean arch forms were generated. The remaining cases (dataset 2) were mapped into the obtained clusters and a multivariate test was performed to assess the differences between the clusters. Results: Four-cluster classification demonstrated maximum inter-cluster distance. Wide, narrow, tapering, and ovoid types were described according to the intercanine and intermolar widths and their best-fit curves were depicted. No significant differences in arch depths existed among the clusters. Strong to moderate correlations were found between maxillary and mandibular arch widths. Conclusions: Lingual arch forms have been classified into 4 types based on their anterior and posterior dimensions. A template of the 4 arch forms has been depicted. Three-dimensional analysis of the lingual bracket points provides more accurate identification of arch form and, consequently, archwire selection.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.3
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• pp.431-443
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• 1994

As the dental arch is the curve connecting the cusp tip of tooth, the dental arch form, composing of the occlusion, is one the important factors of occlusal reconstruction. Many studies about the horizontal dental arch form have been reported, but until now, it is unclear to infer the position of the teeth in dental arch form, to evaluate the effect of the horizontal dental arch form on chewing movement. The purpose of this study is to make objective criteria to infer the position of the teeth in dental arch. In this study, 100 subjects with individdual normal occlusion were evaluated. By multiple regression analysis on the basis of the relation of the canine and the first molar, the positions of teeth in dental arch were inferred. According to buccolingual relationship of maxillary to mandibular posterior teeth, the dental arch forms were classified into five groups, i, e. the normal group, the group which the maxillary second molar positions buccal side, the group which the maxillary premolars position buccal side, the group which the maxillary premolar position lingual side. From the results, objective criterial to infer the positons of the first premolar, the second premolar, the second molar in dental arch were made.

• The korean journal of orthodontics
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• v.35 no.1 s.108
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• pp.15-22
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• 2005

The Purpose of this study was to clarity 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 on 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 oi 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 Journal of Korean Academy of Prosthodontics
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• v.32 no.4
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• pp.565-572
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• 1994

According to the classification of dental arch form and the analysis of patterns of chewing movement, the patterns of chewing movement in each group were evaluated and compared with those of the normal group. Results were summarized as follows ; 1. Opening phase in chewing movement In the group which the maxillary second molar positionsbuccal side, the chewing patterns which have the Vertical Guide Openings in frontal plane, the Posterior Guide Openings in hjorizontal plane were observed. In the group which the maxillary premolars position lingual side, the chewing paterns which have the Protrusive Shift Openings in horizontal plane and sagittal plane were observed. 2. Closing phase in chewing movement. In each group except for the normal group, the chewing patterns which have the Concave Closure in frontal plane and in Horizontal plane were observed. In the group which the maxillary premolars position buccal side, the chewing patterns which have the Lateral Guide Closure in frontal plane and in horizontal plane, the Vertical Guide Closre in sagittal plane were observed: From the results, as the characteristics of the dental arch form have appeared in chewing movement, the close relationships were found between dental arch form and chewing movement. It is suggested that the evaluation of dental arch form is effective in the diagnosis of function of stomatognathic system.

• The korean journal of orthodontics
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• v.40 no.5
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• pp.334-341
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• 2010

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.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.2
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• pp.235-248
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• 1994

There were many studies that distribute the partial edentulous states and examine the removable partial denture designs in the planning of removable partial denture treatment. This study was performed in the point of removable partial denture prescription to evaluate partial edentulism and its removable partial denture designs. The data was collected from the dental laboratory of each three dental colleges in Seoul and from two dental laboratories only for removable partial dentures as a prescription form. A total of 1411 cases with prescription form collected from dental laboratories were distributed for this study, then 788 cases were selected for this study. The case selection was done according to the contents of prescription form. The selected cases were divided into maxillary arch and mandibular and classified in terms of types of major connector and direct retainer, unbroken anterior teeth, Kennedy classification, the number of remaining teeth, and distribution of age and sex. The analyzed results were as follows : 1. The Kennedy classification I showed highest frequency both in maxilla and mandible. 2. The arch distribution of removable partial denture was 50.08% for maxilla and 49.92% for mandible. 3. The highest frequency in the distribution of direct retainer was the RPA clasp design. 4. The frequency of unbroken anterior 6 was 73.36% for maxilla and 82.30% for mandible. 5. The design of broad palatal strap and lingual bar revealed the highest prevalence in the major connector construction. 6. The mean number of remaining teeth per arch was 8.25 for maxilla and 8.37 for mandible. 7. The mean age of the patients supplied with removable partial denture was 52.25 years for men, 51.68 years for women, 52.11 years for maxilla, and 51.76 years for mandible and women showed more prevalence.

• The korean journal of orthodontics
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• v.37 no.5
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• pp.364-375
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• 2007

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.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.1-11
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• 2004

Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch fen the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. $\cdot$ Angle classification I malocclusion with bialveolar protrusion $\cdot$ Extraction of 4 1st bicuspids $\cdot$ No tooth anomaly or prosthesis $\cdot$ No abnormal attrition $\cdot$ No ectopically erupted teeth $\cdot$ Angle classification I canine and molar relationship $\cdot$ Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the Posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.4
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• pp.553-564
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• 1994

Using Sirognathograph Analyzing System, the patterns of chewing movement were analyzed into opening phase and closing phase, each phase to frontal plane, horizontal plane, and sagittal plane by maruyama's classification. In opening phase, the chewing patterns of frontal plane were classifed into Chopping Opening, Grinding Opening, Concave Opening, Lateral Shift Opening, Vertical Guide Opening, Convergence Opening. Those of horizontal plane were classified into Chopping Opening, Grinding Opening, Concave Opening, Protrusive Shift Opening, Posterior Guide Opening, Convergence Opening. Those of sagittal plane were classified into Normal Opening, Protrusive Shift Opening, Vertical Guide Opening, Convergence Opening. In closing phase, the chewing patterns of frontal plane were classified into Normal Closure, Concave Closure, Lateral Shift Closure, Lateral Guide Closure, Vertical Guide Closure, Convergence Closure, Those of horzontal plane were classified into Normal Closure, Concave Closure, Lateral Shift Closure, Protrusive Shift Closure, Lateral Guide closure, Posterior Guide Closure, Convergence Closure. Those of sagittal plane were classified into Normal Closure, Protrusive Shift Closure, Vertical Guide. Closure, Convergence Closure. Results were summarized as follows : 1. Opening phase in chewing movement The Normal Openings in 3 planes(frontal, horizontal, sagittal), the Concave Openings in frontal plane and horizontal plane, the Vertical Guide Opening in frontal plane and the Posterior Guide Opening in horizontal plane were many observed. 2. Closing phase in chewing movement The Concave Closure in frontal and horizontal plane, the Normal Closure in 3 planes (frontal, horizontal, sagittal), the Concave Closure in horizontal plane were many observed.