• The korean journal of orthodontics
• /
• v.50 no.3
• /
• pp.216-226
• /
• 2020

Root resorption can be caused by several factors, including contact with the cortical bone. Here we report a case involving a 21-year-old female with Angle Class II, division 1 malocclusion who exhibited significant root resorption in the maxillary right central incisor after orthodontic treatment. The patient presented with significant left-sided deviation of the maxillary incisors due to lingual dislocation of the left lateral incisor and a Class II molar relationship. Cephalometric analysis demonstrated a Class I skeletal relationship (A point-nasion-B point, 2.5°) and proclined maxillary anterior teeth (upper incisor to sella-nasion plane angle, 113.4°). The primary treatment objectives were the achievement of stable occlusion with midline agreement between the maxillary and mandibular dentitions and appropriate maxillary anterior tooth axes and molar relationship. A panoramic radiograph obtained after active treatment showed significant root resorption in the maxillary right central incisor; therefore, we performed cone-beam computed tomography, which confirmed root resorption along the cortical bone around the incisive canal. The findings from this case, where different degrees of root resorption were observed despite comparable degrees of orthodontic movement in the bilateral maxillary central incisors, suggest that the incisive canal could be an inducing factor for root resorption. However, further investigation is necessary to confirm this assumption.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.38 no.1
• /
• pp.75-81
• /
• 2011

Supernumerary teeth are in excess of the normal number of teeth in either the primary or permanent dentitions. They are classified into supplemental teeth resembling those of the normal series and rudimentary teeth with abnormal shapes, according to their form. Most of the supernumerary teeth are rudimentary form, and supplemental teeth are much less common. Sulppemental teeth are most common in the permanent maxillary lateral incisor area and clinicians should be careful with differential diagnosis from normal teeth. Unerupted supernumerary teeth may produce several complications such as delayed eruption, displacement of permanent teeth, diastema, root resorption and cyst formation. Early detection and proper treatment plan according to the tooth alignment and root formation stage are important. Here we report 3 cases of unilateral or bilateral normal incisor shaped supernumerary lateral incisors treated by eruption observation, surgical extraction and orthodontic treatment with resin build-up.

• The Journal of the Korean dental association
• /
• v.48 no.11
• /
• pp.819-828
• /
• 2010

Activator is a removable functional appliance used for correcting the skeletal Class II malocclusion in children with the mandibular deficiency. Berlin standard activator modified from Andresen activator has following characters; do not cover the palatal surface for tongue space, relief on lingual surface of mandibular incisors and resin capping 1/3-1/2 of crown height on mandibular incisors for preventing labioversion of mandibular incisors, L-hook between maxillary lateral incisor and canine for anterior high pull headgear, relief on mandibular posterior bite block for differential eruption of posterior teeth. Two cases presented here had a mandibular deficiency and slight maxillary protrusion. First case (an 11-year-old girl) treated with Berlin standard activator and anterior high pull headgear for 13 months followed by fixed orthodontic appliance for another 29 months. Second case (a 12-year-old boy) treated with Berlin standard activator for 6 months followed by fixed appliance for another 24 months. Treatment results showed a significant improvement in sagittal skeletal and occlusal relationship without premolar extraction. Mandibular condyles were concentric in TMJ [ossa, and masticatory muscle activities were normalized after treatment. In the retention period facial harmony and occlusal stability was maintained.

• The korean journal of orthodontics
• /
• v.49 no.5
• /
• pp.310-318
• /
• 2019

Objective: This study aimed to identify possible risk factors for external apical root resorption (EARR) in the maxillary incisors after orthodontic treatment. Methods: The root length of 2,173 maxillary incisors was measured on periapical radiographs of 564 patients who received orthodontic treatment. The Kappa test was performed to evaluate intraexaminer and interexaminer reproducibility. Multiple binary logistic regression was used to determine the association between EARR and various factors. Odds ratios and 95% confidence intervals were reported. Results: The risk of developing EARR was 70% higher in orthodontic treatment with maxillary premolar extraction (p = 0.004), 58% higher in patients with increased overjet (p = 0.012), 41% lower in two-phase orthodontic treatment (p = 0.037), and 33% lower in patients with deep bite (p = 0.039). The lateral incisors were 54% more likely to develop EARR (p < 0.001), dilacerated roots were 2.26 times more likely to develop EARR (p < 0.001), and for each additional millimeter of root length, the risk of EARR increased by 29% (p < 0.001). Conclusions: The potential risk factors for EARR after orthodontic treatment included treatment with maxillary premolar extraction, increased overjet at the beginning of treatment, and dilacerated roots.

• The korean journal of orthodontics
• /
• v.35 no.2 s.109
• /
• pp.137-147
• /
• 2005

The purpose of this study was to investigate the stress distribution in the periodontal tissue and the displacement of teeth when active torque was applied to the maxillary incisors by three-dimensional finite element analysis A three-dimensional finite element model consisted of the maxillary teeth and surrounding periodontal membrane, $.022{\times}.028$ Roth prescription bracket and stainless steel, NiTi and TMA rectangular ideal arch wires which were modeled by hexahedron elements. Applied active torques were 2, 5 and 10 degrees ThHe findings of this study showed that the reaction force acting or the bracket was the extrusion force on the mesial side of the incisors and canine and the intrusion force on the distal side of the incisors and canine. The amount of force and moment was greatest at the lateral incisor. When active anterior labial crown torque was applied. labial crown and distal tipping and Intrusion of the incisors took place. and lingual crown distal tipping and extrusion of the canine occured. An excessive force was concentrated on the lateral incisor, when the stainless steel wire was used NiTi or TMA wire is desirable for torque control.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.24 no.1
• /
• pp.39-46
• /
• 1994

The purpose of this study was to evaluate the prevalence and distribution according to the types of tooth shape anomalies in permanent teeth of 6,082 persons by means of analysis of the full mouth periapical radiographs. And the following results were obtained ; 1. Among tooth shape anomalies, the highest incidence was observed on dilaceration (20.14%), foll owed by dens invaginatus(3.02%), peg lateralis(1.48%), taurodontism (0.34%), dens evaginatus (0.33%), talon cusp(0.20%), fusion(0.07%) and gemination(0%) in descending order of frequency. 2. Peg lateralis, dens invaginatus and dilaceration occurred more prevalent in females, and other types of tooth shape anomalies occurred more prevalent in males. 3. Dens evaginatus and taurodontism occurred with bilateral tendency, but other anomalies occur- ed with unilateral tendency. 4. As to the involved teeth, maxillary lateral incisors were the most frequently involved teeth on peg lateralis, dens invaginatus and talon cusp. And the mandibular premolars were the most frequently involved teeth on dens evaginatus, the maxillary first molars were on taurodontism, the maxillary second premolars were on dilaceration, and the mandibular incisors and canines were on fusion.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.22 no.2
• /
• pp.185-193
• /
• 1992

The purpose of this study was to evaluate the prevalence and distribution of tooth number anomaly by means of the analysis of panoramic radiographs in 6,531 patients visited the Dental Infirmary of Kyungpook National University Hospital from January 1983 to May 1992. The results were as follows: 1. The prevalence of congenitally missing teeth except third molar was revealed to be 10.8%, and there was a hihger prevalence in females(44.6%) than in males(55.4%). Mandibular 2nd premolars(23.2 %) were absent most frequently, followed by maxillary lateral incisors(18.4 %), mandibular lateral incisors(18.3%), and maxillary second premolars(15.4 %) in descending order of frequency. As to the number of congenitally missing teeth, the percentage of missing one tooth was 48%, missing two teeth was 35.4 %, missing three teeth was 6.6%. 2. he prevalence of congenitally missing third molars was revealed to be 39.7%. There was a higher prevalence n the maxilla(60.3%) than in the mandible(39.7%). Maxillary right 3rd molars(30.6%) were absent most frequently, followed by maxillary left 3rd molar(29.7%), mandibular right 3rd molar(202%), mandibular left 3rd molar(19.5%) in descending order of frequency. 3. The prevalence of supernumerary teeth was revealed to be 4.2%, and there was a higher prevalence in males(65.7%) than in females(34.3 ). They were ound most frequently in maxillary central incisor area(64.8%), followed by maxillary lateral incisor area(132%), posterior area of maxillary third molar(8.7%) in descending order of frequency. As to the number of supernumerary teeth; The percentage of one supernumerary tooth was 79.9%, two supernumerary teeth was 8.9%, three supernumerary teeth was 1.2 %.

• Journal of Periodontal and Implant Science
• /
• v.35 no.2
• /
• pp.359-369
• /
• 2005

It has been suggested that morphologic characteristics of the periodontium are partly related to the shape and form of the teeth. Furthermore, the severity of symptoms of periodontal disease have been proposed to differ among these various morphologic entities or "biotypes". The purpose of the present study was to examine the relationship between the form of the crowns in the maxillary anterior tooth segment and (1) a group of morphological characteristics and (2) the thickness of the gingiva. The thickness of gingiva was measured by ultrasonic device(SDM). 100 subjects devoid of symptoms of destructive periodontal disease were examined regarding, e.g., probing depth, gingival recession, width of keratinized gingiva, thickness of the keratinized gingiva. From maxillary study cast, the width(at the apical third-CW) and the length(CL) of the crowns of the 6 anterior teeth were determined. A CW/CL-ratio was calculated for each tooth and averaged for each tooth region. The individual mean CW/CL-ratio values for the central incisors were ranked. The 10 subjects ranked highest and the 10 ranked lowest were selected as having either a long-narrow(group N) or a short-wide(group W) form of the crown of the tooth. The data for each of the examined parameters were averaged for each tooth region in each subject and mean values for subjects in groups W and N were compared using the Student t-test. Stepwise multiple regression analysis, including data from the whole sample, was performed for each tooth region with the thickness of the free gingiva as the dependent variable. The results from the analyses demonstrated that individuals with a long-narrow form of the central incisors displayed, compared to individuals with a short-wide crown, form (l) a narrow zone of keratinized gingiva, (2) a pronounced "scalloped" contour of the gingival margin. There was no significant difference between groups N and W with respect to the thickness of the keratinized gingiva. The CW/CL-ratio data revealed that a certain form of the crowns in the central incisors was accompanied by a similar form in the lateral incisors and canine tooth region. The regression analyses demonstrated that the thickness of the keratinized gingiva in central, lateral incisors and canines was significantly related to the width of the keratinized gingiva.

• The Journal of Advanced Prosthodontics
• /
• v.4 no.2
• /
• pp.72-75
• /
• 2012

PURPOSE. This study evaluated the existence of golden proportion between the widths of the maxillary and mandibular anterior teeth in Indian population. MATERIALS AND METHODS. The clinical tooth width measurements were recorded with the digital vernier calipers on 576 patients of both sexes in the age group of 21 - 30 years. Flexible ruler was used to determine the width of maxillary and mandibular anterior teeth on the patients by the same operator. The data obtained was statistically analyzed using paired student t-test (${\alpha}$=.05). RESULTS. The golden proportion was not found between the width of the right central and lateral incisors in 53% of women and 47% of men. The results revealed the golden percentage was rather inconstant in terms of relative tooth width. CONCLUSION. The golden proportion is an inappropriate method to relate the successive widths of the maxillary anterior teeth in Indian population.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.7 no.1
• /
• pp.21-32
• /
• 1980

The purpose of this study is to determine the developmental relationship between the maxillary primary central incisors and their permanent successor. The auther took 315 cases of lateral cephalogram of the children (males were 171, females were 141) Angular change of the teeth and horizontal and vertical linear change were observed. The obtained results were as follows: 1. The inclination of the long axes of both incisor teeth was relatively stable and labio-version of both incisore was significant at 7 years of age. 2. The distance between the incisal edge of the permanent central insisor and the resorbing apex of the primary maxillary central incisor remained within 2mm of each other, 3. Vertical growth of the maxillary anterior portion was greater than horizontal growth from 6 to 7 years of age. 4. There was not a significant sexual difference.