• The korean journal of orthodontics
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• v.46 no.5
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• pp.290-300
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• 2016

Objective: This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods: Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results: An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions: The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.4
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• pp.320-328
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• 2006

Purpose: The aim of this study was to evaluate the effects of pterygomaxillary separation on dimensional changes of dental arch following surgically-assisted rapid maxillary expansion (SARME). Patients and Methods: Eighteen adults who had been treated by SARME for transverse maxillary deficiency from May 2000 to August 2005 were evaluated. Thirteen patients (Group 1) were treated with subtotal Le Fort I osteotomy including pterygomaxillary separation and anterior midpalatal osteotomy. The same operation was performed in five patients (Group 2) except pterygomaxillary separation. Dental study casts were taken before operation and after removal of expansion device. And then, skeletal and dental parameters were measured pre- and post-operatively. Results: 1. Changes of mean interdental width 1) In group 1, mean maxillary interdental width was increased 70%($47{\sim}99%$), 95%($84{\sim}115%$), and 77%($57{\sim}94%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 2) In group 2, mean maxillary interdental width was increased 77%($59{\sim}100%$), 78%($45{\sim}107%$), and 86%($57{\sim}116%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 3) There was a statistical difference between the change of interdental width of group 1 and group 2 at first premolar(p<0.05). 2. Changes of mean interalveolar width 1) In group 1, mean maxillary alveolar bone width was increased 66%($42{\sim}84%$), 74%($42{\sim}104%$), and 57%($31{\sim}78%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 2) In Group 2, mean maxillary alveolar bone width was increased 73%($55{\sim}98%$), 67%($36{\sim}89%$), and 59%($48{\sim}73%$) of total expansion on canine, first premolar, and first molar region, respectively after retention. 3) There were no statistical differences between group 1 and group 2 at each teeth area. Conclusion: These results suggest that SARME without pterygomaxillary separation may allow the relatively equal expansion at both anterior and posterior teeth area and most amounts of maxillary interdental expansions were acquired with the expansion of the maxilla by SARME.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.322-331
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• 2016

Variation in the root and canal morphology of the maxillary first molars is quite common. The most common configuration is 3 roots and 3 or 4 canals. Nonetheless, other possibilities still exist. The presence of an additional palatal root is rather uncommon and has been reported to have an incidence of 0.06 - 1.6% in varying populations studied. Whenever two palatal roots exist, one of them is the normal palatal root, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis) or distolingually (radix distolingualis). This case report describes successful endodontic treatment of a maxillary first molar with radix mesiolingualis and radix distolingualis. Identification of this variation was done through clinical examination along with the aid of multiangled radiographs, and an accurate assessment of this morphology was made with the help of a cone-beam computed tomography imaging. In addition to the literature review, this article also discusses the epidemiology, classifications, morphometric features, guidelines for diagnosis, and endodontic management of a maxillary first molar with extra-palatal root.

• Journal of Periodontal and Implant Science
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• v.41 no.3
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• pp.143-148
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• 2011

Purpose: Few epidemiologic studies have investigated aggressive periodontitis in Koreans, but such studies of disease prevalence and other clinical characteristics would be invaluable in providing proper treatment. The aim of this study was to assess the prevalence of aggressive periodontitis and to measure the extent of associated periodontal breakdown. Methods: The study population consisted of 1,692 patients who visited the Department of Periodontology, Wonkwang Daejeon Dental Hospital from January to December, 2010. Clinical parameters (probing depth, gingival recession, periodontal attachment loss) were measured by a single examiner, and radiographic examination was performed at the baseline. Results: Twenty-eight (1.65%) patients showed clinical features of aggressive periodontitis, of which 27 patients exhibited the generalized form, and 1 exhibited the localized form. There was no significant difference between the percentage of male and female patients. The probing pocket depth of the maxillary first molar was deeper than that of the other teeth and gingival recession was also the most serious at the maxillary first molar. The periodontal attachment loss was the highest at the maxillary first molar. The average number of missing teeth was 1.29 per subject. Loss of the second molar was prominent. Conclusions: Within the limitations of this study, the periodontal breakdown evaluated by attachment loss was found to be most severe at the first molars of aggressive periodontitis patients. However, further large scale multicenter studies are necessary to access more precise data, including prevalence.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.1
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• pp.63-67
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• 2022

Controversies exist regarding the need for prophylactic extraction of mandibular third molars in patients who plan to undergo orthognathic surgery. An 18-year-old male patient was diagnosed with mandibular prognathism and maxillary retrognathism with mild facial asymmetry. He had a severely damaged mandibular first molar and a horizontally impacted third molar. After extraction of the first molar, the second molar was protracted into the first molar space, and the third molar erupted into the posterior line of occlusion. The orthognathic surgery involved clockwise rotation of the maxillomandibular complex as well as angle shaving and chin border trimming. Patients who are missing or have damaged mandibular molars should be monitored for eruption of third molars to replace the missing posterior tooth regardless of the timing of orthognathic surgery.

• Restorative Dentistry and Endodontics
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• v.28 no.3
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• pp.232-240
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• 2003

This study is to investigate the canal system in the mesiobuccal root of the maxillary first molar. 61 maxillary first molars were randomly selected. Serial transverse sections were made perpendicular to the long axis of the mesiobuccal root. Each section was placed in 3% sodium hypochlorite for 24 hours and rinsed in water and dried. The resected surface was stained with 2% methylene blue dye and examined with stereomicroscope. 1 Canal configuration analysis showed that 36.1% of the specimen classified as type I, 16.4% as type II , 37.7% as type III and 9.8% as type IV. 2. Type II canal was merged in one canal within 1 to 4mm of the apex. 40% of type II canal converged at 2mm of the apex. 3. Type IV canal was divided into two canal within 2 to 4mm of the apex. 66.6% of type IV canal branched off at 2mm of the apex. 4. None of the sections had more than two main root canal. 5. 48.4% of the sections in 3mm with two canals contained an isthmusand more than 70% with two canals has isthmus at 4 to 5mm sections. 63.9% of the mesiobuccal root of maxillary first molar had two canaland 76.5% of sections with two canals in 5 MM had an isthmus. Because of this complexity the clinician should always search for extra canal carefullyand root canal system, including an isthmus, should be cleaned and shaped completelyand obturated three dimensionally for successful endodontic treatment.

• The korean journal of orthodontics
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• v.49 no.6
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• pp.349-359
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• 2019

Objective: The aim of this study was to analyze three-dimensional (3D) changes in maxillary dentition in Class II malocclusion treatment using arch wire with continuous tip-back bends or compensating curve, together with intermaxillary elastics by superimposing 3D virtual models. Methods: The subjects were 20 patients (2 men and 18 women; mean age 20 years 7 months ${\pm}$ 3 years 9 months) with Class II malocclusion treated using $0.016{\times}0.022-inch$ multiloop edgewise arch wire with continuous tip-back bends or titanium molybdenum alloy ideal arch wire with compensating curve, together with intermaxillary elastics. Linear and angular measurements were performed to investigate maxillary teeth displacement by superimposing pre- and post-treatment 3D virtual models using Rapidform 2006 and analyzing the results using paired t-tests. Results: There were posterior displacement of maxillary teeth (p < 0.01) with distal crown tipping of canine, second premolar and first molar (p < 0.05), expansion of maxillary arch (p < 0.05) with buccoversion of second premolar and first molar (p < 0.01), and distal-in rotation of first molar (p < 0.01). Reduced angular difference between anterior and posterior occlusal planes (p < 0.001), with extrusion of anterior teeth (p < 0.05) and intrusion of second premolar and first molar (p < 0.001) was observed. Conclusions: Class II treatment using an arch wire with continuous tip-back bends or a compensating curve, together with intermaxillary elastics, could retract and expand maxillary dentition, and reduce occlusal curvature. These results will help clinicians in understanding the mechanism of this Class II treatment.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.1
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• pp.27-31
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• 2010

Purpose of study: The purpose of this study was to provide adequate diagnostic guideline for the maxillary sinuses prior to dental implant treatment for edentulous posterior maxillary areas. For this purpose, our procedure involves the estimation of the remaining alveolar bone height, the examination of the anatomical variation in the maxillary sinuses (e.g. sinus septum), and the evaluation of the incidence of preoperative pathological conditions in the maxillary sinuses. Materials and Methods: We selected 189 patients to undergo computerized tomography (CT) in order to account for the posterior maxillary anatomy found in patients of Korean ethnicity. We evaluated the following using Dentascan software: Remaining alveolar bone height, incidence of sinus septum, and rate of preoperative pathologic conditions in the maxillary sinus. The average amount of remaining alveolar bone height was analyzed using the student's t-test for differences according to anatomical site, and the ANOVA was used for the differences according to age group with the level of significance set at 0.05. Results: Alveolar bone heights of upper first premolar, second premolar, first molar, and second molar was 12.24 mm, 10.37 mm, 7.16 mm, and 7.15 mm, respectively with statistical significance (P < 0.05). Incidence of sinus septum as an anatomic variation was 17 out of 189 cases (9.0%). Incidence of mucosal thickening as a pathologic variation was 82 out of 189 cases (43.4%). Conclusion: In treatment planning of posterior maxillary edentulous area of Koreans, the consideration of augmentation surgery for maxillary sinus is required in maxillary molar area before dental implant installation, and preoperative screening of the asymptomatic maxillary sinuses can be regarded as a reasonable preoperative procedure in the planning of dental implant treatment on the posterior maxillary edentulous area.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.1
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• pp.61-67
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• 2000

It was the aim of present study to grope the relationship of the maxillary first molar width to the various transverse skeletal measurements in frontal headfilm, and to formulate the predictive equations of the maxillary intermolar width (U6-U6) from each of the variables. Frontal cephalograms of 17 males from 18 to 26 YO and 13 females from 17 to 25 YO who manifested balanced skeletal profiles, normal occlusion, and no history of orthodontic and prosthodontic treatment were employed as subjects. Nine transverse measurements were scrutinized with Pearson's correlation analysis, simple and stepwise multiple regression analysis in specific regards to the intermolar width of maxillary first molar. Statistical output demonstrated that there were intimate relationships within the various transverse skeletal measurements each other, and among the others, high correlation was found between facial width and maxillary first intermolar width. Regression analyses provided the reliable and clinically applicable predictive equations to set the ideal maxillary first intermolar width(U6-U6) from the given skeletal framework.

• Journal of the korean academy of Pediatric Dentistry
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• v.5 no.1
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• pp.12-18
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• 1978

The author has observed the ectopic eruption pattern on oblique cephalogram of 195 children. (5years: 78, 6 years: 58, 7 years: 59). The results were as follows; 1) Making a comparison between hold type and jump type of ectopic eruption, there are 4 cases in Hold type, 5 cases in jump type. 2) Making a comparison of ectopic eruptin between male and female, there are 7 cases in male, 2 cases in female. 3) Making a comparison of ectopic eruption between right side and left side, there are 5 cases at right side, 4 cases at left side. 4) Making a comparison of ectopic eruption among 5 years to 7 years, there are 4 cases in 5 years, 3 cases in 6 years, 2 cases in 7 years. 5) The prevalence of ectopic eruption of the maxillary first molar was 4.61%. 6) Normal eruption angle of the maxillary first molar is prevailing in $80^{\circ}{\sim}85^{\circ}$.