• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.88-94
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• 2020

Purpose: The purpose of this study was to analyze the sagittal root position of maxillary anterior teeth and report the frequency of each classification in Korean for immediate implant placement. Materials and Methods: A retrospective review of cone-beam computed tomography (cone-beam CT) images was conducted on 120 patients (60 male and 60 female) who fulfilled the inclusion criteria. After reorientation of the axis, cone-beam CT images were evaluated and the relationship of the sagittal root position (SRP) of the maxillary anterior teeth to its associated osseous housing was recorded. Class I, II, and III were classified respectively when the root was positioned on the labial, central, and palatal aspect of the alveolar bone. Class IV was the position that at least two thirds of the root is engaging both the labial and palatal cortical plates. Then, the angulation of the root axis and the alveolar bone axis was measured. Descriptive statistics and Kruskal-Wallis test were used to compare the angulation according to the root position and SRP class. Results: The frequency distribution of sagittal root position of maxillary anterior teeth indicated that 81.1%, 10.3%, 1.9%, and 6.7% were classified as Class I, II, III, and IV, respectively. The sagittal angulation at approximately 77.5% of central incisor, lateral incisor, and canine was < 20 degrees, but the angle at more than 42.7% of canine was ≥ 20 degrees. Within the class, the angulation was statistically significantly greater in Class I (16.19) compared to Class II (8.72) and Class III (9.93), and smaller in Class IV (3.79). Conclusion: Within the limitation of this study, a majority of the maxillary anterior roots were positioned close to the buccal cortical plate. However, some roots have very thin alveolar bone and sagittal angulation larger than 30 degrees. Therefore, cone-beam CT analyses of the sagittal root position and the sagittal angulation are recommended for the selection of the appropriate dental implant treatment approach.

• The korean journal of orthodontics
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• v.39 no.6
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• pp.362-371
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• 2009

Objective: The purpose of this study was to compare the longitudinal treatment effects of facemask with rapid maxillary expansion (FM/RME) and chincup (CC) therapy followed by fixed orthodontic treatment (FOT) in Class III malocclusion (CIII) patients. Methods: The samples consisted of twenty-one CIII patients who had similar skeletal and dental characteristics before FM/RME or CC therapy and good retention results (Class I molar/canine relationship and positive overbite/overjet) after FOT (Group 1, FM/RME, n = 11; Group 2, CC, n = 10). Lateral cephalograms were taken before (T0) and after FM/RME or CC therapy (T1), and after FOT and retention (T2). Skeletal and dental variables were measured. Mann-Whitney U-test and Wilcoxon signed-rank test were used for statistical analysis. Results: During T0-T1, FM/RME therapy induced forward movement of point A, and labioversion of the upper incisors. Both groups showed posterior repositioning of the mandible. FM/RME resulted in increase of the vertical dimension; however, CC caused an increase in articular angle and decrease in gonial angle. During T1-T2, both groups exhibited forward growth of point A. Group 1 showed forward growth and counterclockwise rotation of the mandible and increase of IMPA; however, Group 2, showed increase of ANS-Me/N-Me and decrease of overbite. Conclusions: The key factor for successful FM/RME and CC therapy and good retention results might be a harmonized forward growth of the maxilla that could keep pace with the growth and rotation of the mandible.

• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.563-580
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• 1998

This study was designed to analysis the displacement and stress distribution of individual tooth by orthodontic force during distal on masse movement of the maxillary dentition. In this study, three dimensional finite element analysis was used. Author made the finite element model of maxillary teeth, periodontal ligament, alveolar bone and bracket with anatomic and physiologic characteristics on computer. Author analysed and evaluated the displacement and stress distribution of individual tooth when extraoral force, Class II intermaxillary elastics, ideal arch wire, MEAW and tip back bend were used for distal on masse movement of the maxillary dentition. These analyses were also applied in the case of the maxillary second molar were not extracted. Author compared the results of the cases which maxillary second molar were extracted or not. The results were expressed quantitatively and visually. Author obtained following results, 1. When anterior headgear was applied, the posterior translation, posterior tipping, and vertical displacement of teeth were produced more in the anterior segment of the dentition. 2. When Class II intermaxillary elastics were applied in the ideal arch wire, the teeth displacement were usually produced in the anterior segment. But when tip back bend were added in the ideal arch wire, the orthodontic force produced by elastics were transmitted to the posterior segment. As increasing the tip back bend, posterior translation and lingual tipping of anterior teeth were decreased, posterior translation and tipping displacement of posterior teeth were increased, and extrusion of anterior teeth by Class II elastics were decreased 3. When MDAW and Class II elastics were applied, the teeth movement were sir flu with the case of ideal arch wire and Class II elastics, but more small and uniform teeth displacement were produced Compared with the ideal arch wire, posterior tipping of the posterior segment were more produced than lingual tipping displacement of the anterior segment. 4. When the maxillary second molar without orthodontic appliance existed, the displacement of maxillary first molar were decreased.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.506-512
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• 2007

Traumatic injury of tooth in children is commonly occurred problem. It is classified into tooth, periodontal tissue, supporting bone, soft tissue injury by it's area and extent. Among the periodontal tissue injuries, traumatically intruded teeth are common in anterior maxillary area, though the occurrence rate is rather low, the pulp and supporting tissue injury is possible by vertical impact. The treatment method of traumatically intruded teeth is various. Observation on the spontaneous reeruption for 3-4 weeks is recommended if the traumatized teeth are deciduous teeth or slightly intruded immature permanent anterior teeth. If this did not occur because the extent of intrusion is severe or the traumatized teeth are mature permanent anterior teeth, orthodontic traction is applied by fixed/removable appliances. At this time, light and continuous force is applied for the extrusive movement of the intruded teeth. When above procedures are impossible, surgical repositioning and fixation is recommended. In these cases, we performed conventional endodontic therapy for pulp necrosis and orthodontic traction with fixed appliance. We obtained satisfactory results and will report that.

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

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.547-556
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• 1996

The purpose of this study was to evaluate the skeletal, dental and soft tissue profile changes following the face mask therapy in growing skeletal class III malocclusion patients. The fifteen patients with the good results were selected among the patients who visited the Department of Orthodontics in Seoul National University Hospital. The mean age was 10.63(range 7.25-13.25) years and the mean treatment duration was 9.84(range 2.00-27.00) months. Lateral cephalograms were taken just before and after face mask application. After tracing the cephalograms, thirty five items(twety angular and fifteen linear) were measured. The differences before and after the face mask therapy were compared statistically by the paired t-test(p<0.05). The results were as follows : SNA and Co-A(effective maxillary length) increased significantly after using the face mask(p<0.001), which reflects the orthopedic changes of maxilla. SNB and Co-Gn(effective mandibular length) also showed an increase(p<0.01), which may be a result of the strong growth trends of the samples. FMA, SN-GoGn and Y-axis angle increased significantly(p<0.01), which means the backward and downward rotation of the mandible. This positional change seemed to have compensated an increase of effective mandibular length. There was no statistically significant difference in angulation of upper and lower incisors between pre-treatment and post-treatment(p>0.05). In soft tissue profile, the upper lip was positioned anteriorly(p<0.01) after treatment and approximated to the normal standards.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.772-781
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• 2016

This study is to set the objective criteria on maxillary incisors shade selection by using the colorimetric Shade-Eye NCC as measuring in CIE $L^*$, $a^*$, $b^*$ values, and look into the meaning by analyzing its values. We explain the purpose of this study and gotten their agreement from patients visiting the dentist, 111 people's (men 50, women 61) three teeth, the maxillary central incisor, maxillary lateral incisor, maxillary canines, total of 333 teeth colorimetry. As a result of comparing the differences in colors between cervical margin and incisal edge, ${\Delta}E^*$ of canine is shown as low as $5.81({\pm}2.98)$, followed by lateral incisor of maxilla as $6.51({\pm}3.23)$ and central incisor of maxilla $7.51({\pm}3.04)$. Females show higher luminosity(L*) than males do in all teeth- central incisor, lateral incisor and canine; in yello chroma(b*) males' central incisor is slightly higher than that of females (p<0.05). Age significantly influences the luminosity and red (a*) and yellow chroma (b*) of central incisor(L*); the luminosity(L*), and yellow chroma(b*) of lateral incisor and canine (p<0.05). Smoking doesn't significantly influence the color of natural teeth. Drinking reduces the luminosity of central incisor as well as red chroma of lateral incisor(p<0.05). A chronic illness is likely to reduce the luminosity of central incisor and lateral incisor(p<0.05).

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.1-13
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• 2001

The extraction lot orthodontic treatment can be adopted for aligning crowded dentition, improving facial esthetics and solving a skeletal discrepancy as alternative for a surgical option. Mandibular second premolar extraction was often selected as treatment plan when there we very little or no space shortage in lower arch or limited retraction of the lower incisors was required. The primary object of this study was evaluate a pretreatment condition and examine the amount of tooth movement ior a mandibular second premolar extraction in growing patients. Pretreatment and posttreatment lateral cephalograms of 14 cases that had their four first premolar extracted (4/4 group), 15 cases with upper first and lower second premolar extraction (4/5 group) were selected. Structural method superimposition was conducted to evaluate a difference of dental change between 4/4 and 4/5 group. The results were as follows, 1. Pretreatment factor for 4/4 extraction or 4/5 extraction choice included maxillary incisor axis to occlusal plane, Class II molar relationship, IMPA and interincisal angle. 2. The amount of molar anterior movement in 4/5 group was greater than that of 4/4 group(p<0.05). 3. There was no significant difference between 4/4 group and 4/5 group in aspects of maxillary tooth movement(p<0.05).

• The korean journal of orthodontics
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• v.39 no.5
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• pp.278-288
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• 2009

Objective: The aim of this study was to investigate the changes in the center of resistance of the maxillary teeth in relation to alveolar bone loss. Methods: A finite element model, which included the upper dentition and periodontal ligament, was designed according to the amount of bone loss (0 mm, 2 mm, 4 mm). The teeth in each group were fixed with buccal and lingual arch wires and splint wires. Retraction and intrusion forces of 200 g for 4 and 6 anterior teeth groups and 400 g for the full dentition group were applied. Results: The centers of resistance were at 13.5 mm, 14.5 mm, 15 mm apical and 12 mm, 12 mm, 12.5 mm posterior in the 4 incisor group; 13.5 mm, 14.5 mm, 15 mm apical and 14 mm, 14 mm, 14.5 mm posterior in the 6 anterior teeth group; and 11 mm, 13 mm, 14.5 mm apical and 26.5 mm, 27 mm, 25.5 mm posterior in the full dentition group respectively according to 0 mm, 2 mm, 4 mm bone loss. Conclusions: The center of resistance shifted apically and posteriorly as alveolar bone loss increased in 4 and 6 anterior teeth groups. However, in the full dentition group, the center of resistance shifted apically and anteriorly in the 4 mm bone loss model.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.305-312
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• 2008

Crown-root fractures occur throughout both crown and root, and are defined as fractures involving enamel, dentin and cementum. The fractures may be grouped according to pulpal involvement into complicated and uncomplicated one. Crown-root fractures often occur on maxillary anterior teeth and comprise 5% of injuries affecting the permanent dentition and 2% in the primary dentition. To restore crown-root fractured tooth, biologic width must be maintained. For maintaining biologic width, such methods as gingivectomy following osteoplasty or orthodontic extrusion or surgical extrusion are available. Surgical extrusion is a method that extracts the tooth and replants the fractured tooth supragingivally. It is indicated when the length of the crown fragment is less than half the length of the clinical root. In these cases, root canal treatment and crown restoration using light-cured composite resin were performed after surgical extrusion. In following periodic examinations, favorable outcome was observed.