• Journal of the korean academy of Pediatric Dentistry
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• v.51 no.3
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• pp.279-289
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• 2024

This study aimed to identify the clinical characteristics of molar root-incisor malformation (MRIM) and provide clinical considerations for treatments. Panoramic radiographs and electronic medical records of 64 patients with MRIM were retrospectively reviewed. Age, gender, follow-up period, medical history, complications, distribution of MRIM teeth, treatment, and prognosis were analyzed. Females were affected 1.56 times more than males, and the average age was 8.2 years. Dental complications, including periapical lesions, abscesses, and alveolar bone loss, were observed in 71.9%, and eruption disturbance of adjacent teeth was noticed in 37.5%. Most patients had medical histories in the first year of life. The most prevalent history was prematurity or low birthweight, followed by neurological conditions, surgeries, medications, and infections. All patients had MRIM on permanent first molars. The primary second molars were the second most frequently involved, followed by maxillary permanent central incisors and primary first molars. The prevalence was low on permanent lateral incisors and canines. Extraction was the most prevalent treatment done on MRIM-affected teeth, and most extraction sockets were managed by the eruption of permanent second molars. Few cases received endodontic treatment but with low success rates. Early detection of MRIM and prompt, appropriate treatment are important to avoid unnecessary discomfort from complications.

• Journal of radiological science and technology
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• v.33 no.2
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• pp.109-120
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• 2010

The purpose of this study was first to analyze the utilization of dental examination through questionnaire to develop a diagnostic reference level of patient doses for dental radiography in korea. 77 dental institutions were classified into three groups: A group for the dental hospitals of the college of dentistry (11 institutions), B group for dental hospitals (30 institutions) and C group for dental clinics (36 institutions). The results were as follows : The mean numbers of unit chairs and medical staffs were 140.2, 15.3 and 5.8 sets, 112.6, 7.3 and 1.7 dentists, 3.1, 0.5 and no one radiologic technologists, and 19.7, 12.5 and 3.3 dental hygienists in A, B and C groups, respectively. The mean numbers of dental X-ray equipments were 14.64, 3.21 and 2.19 in A, B and C groups, respectively. Intraoral dental X-ray unit was used the most, the following equipments were panoramic, cephalometric, and cone-beam CT units. The most used X-ray imaging system was also digital system (above 50%) in all three groups. Insight dental film (Kodak, USA) having high sensitivity was routinely used for periapical radiography. The automatic processor was not used in many dental institutions, but the film-holding device was used in many dental institutions. The utilization rates of PACS in A, B and C groups were 90.9%, 83.3% and 16.7% respectively, and the PACS software program was used the most PiView STAR (Infinitt, Korea). The annual mean number of radiographic cases in one dental institution in 2008 for A group was 6.8 times and 21.2 times more than those for B and C groups, and periapical and panoramic radiographs were taken mostly. Tube voltage (kVp) and tube current (mA) for periapical radiography were similar in all three groups, but exposure time in C group was 12.0 times and 3.5 times longer than those in B and C groups. The amount of radiation exposure in C group, in which dental hygienists take dental radiographs, was more than those in other groups. The exposure parameters for panoramic radiography were similar in all three groups. In conclusion, the exposure parameters in dental radiography should be determined with reference level, not past experiences. Use of automatic processor and film-holding devices reduces the radiation exposure in film system. The quality assurance of dental equipments are necessary for the reduction of the patient dose and the improvement of X-ray image quality.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.1-7
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• 2016

The developmental age of permanent teeth was evaluated in children and adolescents according to age and gender using the Nolla Method. A retrospective study was performed on panoramic radiographs of 1,200 subjects aged 4-15 years, including 50 children for each age/gender group. Three well-trained examiners estimated the developmental stage of upper and lower permanent teeth using the Nolla Method. The inter-examiner reliability was excellent (intra-class correlation coefficient value = 0.973). The mean developmental age was calculated. In boys, Nolla stage 6, indicated by crown completion, was seen in the central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar at 5.4, 6.4, 6.7, 7.5, 7.8, 4.6, and 8.1 years, respectively, in the maxilla and at 4.8, 5.1, 6.0, 6.5, 7.2, 4.5, and 8.0 years, respectively, in the mandible. In girls, Nolla stage 6 was seen at 5.3, 6.0, 6.3, 7.3, 7.7, 4.8, and 8.1 years, respectively, in the maxilla and at 4.8, 5.1, 5.9, 6.5, 7.2, 5.0, and 7.9 years, respectively, in the mandible. In this study, the developmental age of permanent teeth was evaluated in Korean children and adolescents who visited Yonsei University Dental Hospital. This study may be helpful in diagnosis and treatment planning in the clinic.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.41.1-41.6
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• 2016

Background: The goal of this study was to retrospectively evaluate the prognosis of minimal invasive horizontal ridge augmentation (MIHRA) technique using small incision and subperiosteal tunneling technique. Methods: This study targeted 25 partially edentulous patients (10 males and 15 females, mean age $48.8{\pm19.7years$) who needed bone graft for installation of the implants due to alveolar bone deficiency. The patients took the radiographic exam, panoramic and periapical view at first visit, and had implant fixture installation surgery. All patients received immediate or delayed implant surgery with bone graft using U-shaped incision and tunneling technique. After an average of 2.8 months, the prosthesis was connected and functioned. The clinical prognosis was recorded by observation of the peri-implant tissue at every visit. A year after restoration, the crestal bone loss around the implant was measured by taking the follow-up radiographs. One patient took 3D-CT before bone graft, after bone graft, and 2 years after restoration to compare and analyze change of alveolar bone width. Results: This study included 25 patients and 39 implants. Thirty eight implants (97.4 %) survived. As for postoperative complications, five patients showed minor infection symptoms, like swelling and tenderness after bone graft. The other one had buccal fenestration, and secondary bone graft was done by the same technique. No complications related with bone graft were found except in these patients. The mean crestal bone loss around the implants was 0.03 mm 1 year after restoration, and this was an adequate clinical prognosis. A patient took 3D-CT after bone graft, and the width of alveolar bone increased 4.32 mm added to 4.6 mm of former alveolar bone width. Two years after bone graft, the width of alveolar bone was 8.13 mm, and this suggested that the resorption rate of bone graft material was 18.29 % during 2 years. Conclusions: The bone graft material retained within a pouch formed using U-shaped incision and tunneling technique resulted with a few complications, and the prognosis of the implants placed above the alveolar bone was adequate.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.114-118
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• 2009

Sialolithiasis is the formation of calcific concretions within the ductal system of major or minor salivary glands. The submandibular gland is most involved because of its high viscosity of the saliva and the long, curved duct. It may occur at any age but, it is most common in middle-aged adults and rare in childhood. Clinical symptoms in sialolithiasis are variable but, swelling is the most common, followed by the pain. Clinical examination and radiographic examination(panoramic and mandibular occlusal radiographs, sialography, intraoral-, extraoral- ultrasound, CT scan, MRI and sialoendoscopy) can help to confirm a diagnosis and localize a stone. The treatment is surgical intervention, either removal of the sialolith or sialoadenectomy. However, non-invasive techniques including shock-wave lithotripsy, $CO_2$ laser and endoscopic treatment used in selected cases. A 5-Year-old girl referred from private practice for evaluation of a yellowish mass on the floor of the mouth. She complained that it had became three times bigger than four months ago when it was found for the first time and she had some pain on submandibular gland area occasionally. On physical examination, a firm and yellowish mass could be seen at the orifice of the submandibular duct. Diagnosis is the submandibular sialolithiasis in the anterior Wharton`s duct. Under local anesthesia, stone was removed.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.56-63
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• 2017

Delayed eruption of the first molar, without a generalized or localized cause, is usually associated with delayed development of the affected tooth. The aim of this study was to investigate the clinical features of the first permanent molar showing delayed development and eruption, and its association with developmental anomalies of other teeth. Panoramic radiographs of 40 healthy children showing delayed development and eruption of first permanent molars were analyzed. The clinical features of affected first molars and developmental anomalies of other teeth (except third molars) were evaluated. Delayed first molars were more frequent in the maxilla. The incidence of bilateral delayed development of first molars was greater than that of unilateral cases in female patients. In contrast, male patients showed unilateral delayed development of the first molar more frequently. A higher incidence of congenitally missing teeth was observed in patients with delayed first molar. In each case, delayed development or congenital absence was observed in the second molar adjacent to the delayed first molar. Overall, delayed first molar seems to be associated with congenital absence of additional teeth. Understanding the developmental mechanisms of this phenomenon requires further studies.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.128-139
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• 2020

The purpose of this study was to examine the prevalence of developmental anomalies of permanent lateral incisor and eruption disturbances and analyze the association between two components. Panoramic radiographs of 3984 patients (aged 5 to 13 years) who visited the Department of Pediatric Dentistry of Seoul National University Dental Hospital between November 2016 and October 2017 were screened. The prevalence of developmental anomalies of permanent lateral incisors was 10.2%. The most common developmental anomalies were congenitally missing teeth(66.1%), followed by peg lateralis(33.5%). The prevalence of eruption disturbances was 16.5%. Among the patient with developmental anomalies of permanent lateral incisors, associated eruption disturbances were appeared on 31.1% of patients. Peg lateralis(p < 0.001), underdeveloped lateral incisors(p < 0.001) and dens invaginatus(p = 0.004) were associated significantly with eruption disturbance of permanent teeth. Eruption disturbance in patients with peg lateralis and dens invaginatus was most prevalent in maxillary canine. For patients with underdeveloped lateral incisor, eruption disturbance of maxillary central incisor was most frequent. It is important for patients with developmental anomalies of lateral incisors to detect associated eruption disturbance early through regular checkup. Diagnosis and treatment plan in view of such relationships is important in order to treat appropriately at the optimal time.

• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.67-78
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• 1996

This study was performed to compare the TMJ sounds by means of vibration-related items by Sonopak such as integral, high integral, above 300/(0-300) ratio, peak amplitude, peak frequency and median frequency before and after occlusa1 splint therapy as well as counselling, physical modalities. For this study 22 patients with craniomandibular disorders (CMDs) were selected and examined by routine diagnostic procedure for CMDs including Transcranial and Panoramic radiographs and were classified into 3 CMDs subgroups : disc displacement with reduction, disc displacement without reduction, and degenerative joint disease. Visual analogue scale (VAS) about joint sound was recorded during treatment period and VAS treatment index (VAS Ti) was calculated from the VAS data and treatment duration. The author evaluated and compared treatment results by several parmeters such as symptom duration, timing of joint sound, parafunctional habits, trauma, and diagnostic classification. The obtained results were as follows : 1. Before the treatment, the highest value of peak amplitude was observed in disc displacement with reduction group and value of median frequency was highest in degenerative joint disease group. In addition the highest values of peak frequency and ratio ware observed in degenerative joint disease group, though they were not significant. Furthermore the lowest value of high integral was observed in disc displacement without reduction group and though it was not significant, value of integral was lowest in that group. 2. Among 3CMDs subgroups disc displacement with reduction group showed the significantly decreased value of high integral and degenerative joint disease group had the significantly decreased value of integral after conservative treatment including occlusal splint therapy. Conclusively conservative treatment including occlusal splint therapy vay be effective in the treatment of CMDs including TMJ sound. 3. Fair prognosis for conservative treatment was observed in acute group under 6 months than chronic group, 6 months over in symptom duration but there was no statistical difference. The result for conservative treatment was observed slightly poor in subjects with bruxism, clenching, unilateral chewing habit and trauma history but there were no statistical differences.

• Journal of Oral Medicine and Pain
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• v.39 no.2
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• pp.69-77
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• 2014

Purpose: It aims to verify the applicability of existing age estimation methods derived from data of foreign population groups to Korean population groups. Moreover it is to suggest a new way applicable to practical age estimation on the basis of newly calculated regression formulae from data of Korean population groups and develop a subsidiarily applicable method to the existing method. Methods: Ratio of pulp cavity to dental crown was calculated by measuring the height and width of dental crowns and pulp cavities at the cervical line from 4,034 first and second upper molars, first and second upper premolars, first and second lower molars and first and second lower premolars on both left and right sides of 400 patients who had been treated in Dental Hospital of Yonsei University College of Dentistry, and regression equations were derived from the values of the ratio. Results: The equation with correlation coefficients the highest among females was as follows: age=$107.96-75.684{\times}{\sharp}17$ TCHI-$53.741{\times}{\sharp}26$ TCVI-$40.664{\times}{\sharp}45$ TCVI-$56.307{\times}{\sharp}46$ TCVI. Randomized anohter Korean female subjects (n=20) are applicated to the new equation. Mean of error of estimate is 10.322 years, standard deviation is 12.852 years. Minimum of error of estimate is 1.018 years, maximum is 21.365 years Conclusions: The error range of age estimation was found to be slightly wider when the existing regression formulae of Drusini were applied to Korean population groups. Also age estimation in females using the ratio of pulp cavity to dental crown measured with the length and width of dental crowns and pulp cavities from maxillomandibular molars was observed to have the highest reliability in the research. However, we consider that advanced equations of regression are needed to apply to both molars and premolars of males and females in the future.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.1
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• pp.46-52
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• 2002

Purpose : We examined the relationships between the root curvatures of the mandibular third molars and their locations on the mandible, so that it might be contributed to elucidate the origin of the formation and development of the Korean mandibular third molar and help many clinicians to treat the mandibular third molars. Materials and Methods : Panoramic radiographs of 237 patients who had been treated at Korea University Ansan Hospital from March, 2000 to April, 2001 and had bilateral mandibular third molars were examined and analyzed. Results : There was no statistically significant difference between men and women (p<0.05). But there were significantly fewer subjects with bilateral curved roots in bilateral third molars regardless of their status (p<0.01) and were statistically significant differences between the groups with bilateral curved roots in the mandibular third molars with same status and with unilateral curved roots in the mandibular third molars with different status and between the groups with unilateral curved roots in the mandibular third molars with same status and with bilateral curved roots in the mandibular third molars with different status(p<0.05). Subjects with bilateral curved roots in the mandibular third molars with bilateral partial impacted status and with bilateral curved roots in the mandibular third molars with bilateral complete eruption status were significantly fewer (p<0.01) and subjects with the mandibular third molars with partial impacted and complete impacted status and with the mandibular third molars with complete erupted and partial impacted status had significantly fewer bilateral curved roots (p<0.05). Conclusions : When we postulate that it is genetic and environmental factors that affect the root formation, it seems that environmental factors have more effects on the formation of the mandibular third molars than on that of the mandibular first and second molars