• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.122-130
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• 2006

Congenital Missing Teeth(hypodontia, oligodontia) is the developmental absence of one or more teeth. It has been reported as being the most common anomaly of dental development in human, relatively common in the permanent dentition. In a recent review, Vastardis has quoted incidence ranges of $1.6%{\sim}9.6%$ in the permanent dentition. Brook has quoted a prevalence of $3.5%{\sim}6.5%$ in most populations, with severe hypodontia, defined as the absence of six or more teeth, having a prevalence of $0.3{\sim}0.4%$. The most commonly affected teeth are third molars, followed by maxillary lateral incisor, and second premolars. The etiology is unknown, several hypotheses include trauma, nutritional deficiency, infection, metabolic abnormalities, systemic disease and genetic influence. The multiple congenital missing is commonly associated with specific syndrome or severe systemic abnormalities such as cleft lip & palate and Down's syndrome. These cases present that children have multiple congenital missing teeth in the permanent dentition, without any systemic disease. Management of this condition must be considered orthodontic and prosthodontic treatment comprehensively. In these cases, children were treated by space maintainer or orthodontic appliance and follow-up checked.

• Imaging Science in Dentistry
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• v.38 no.3
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• pp.169-176
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• 2008

Purpose : To assess the diagnostic accuracy and value in an imaging technique field through the comparison of cone beam computed tomography and conventional panoramic radiography in assessing the topographic relationship between the mandibular canal and impacted third molars. Materials and Methods : Participants consisted of 100 patients offered the images through cone beam computed tomography and panoramic radiography. PSR-$9000^{TM}$ Dental CT system (Asahi Roentgen Ind. Co., Ltd, Japan) was used as the unit of cone beam computed tomography. CE-II (Asahi Roentgen Ind. Co., Ltd, Japan) and Pro Max (Planmeca Oy, Finland) were used as the unit of panoramic radiography. The images obtained through panoramic radiography were classified into 3 types according to the distance between mandibular canal and root of mandibular third molar. And they were classified into 4 types according to the proximity of radiographic feature. The images obtained through cone beam computed tomography based on the classification above were classified into 4 types according to the location between the mandibular canal and the root and were analyzed. And they were classified into buccal, inferior, lingual, and between roots, according to the location between mandibular canal and root. The data were statistically analyzed and estimated by $X^2$-test. Results : 1. There was no statistical significance according to 3 types (type I, type II, type III) through CBCT. 2. The results of 4 types (type A, type B, type C, type D) through CBCT were as high prevalence of CBCT 1 in type A, CBCT 2 in type B, CBCT 3 in type C, and CBCT1 in type D and those of which showed statistical significance (P value=0.03). 3. The results according to location between mandibular canal and root through CBCT recorded each 49, 25, 17, 9 as buccal, inferior, lingual, between roots. Conclusion : When estimating the mandibular canal and the roots through the panoramic radiography, it could be difficult to drive the views of which this estimation was considerable. Thus it is required to have an accurate diagnostic approaching through CBCT that could estimate the location between mandibular canal and roots.

• The korean journal of orthodontics
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• v.25 no.1 s.48
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• pp.13-18
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• 1995

Craniofacial asymmetry was analyzed in 39 patients with complete unilateral cleft lip and palate(UCLP). The samples are devided into three groups nine below 9 years, twenty three from 9 years 1 month to 14 years and seven over 14 years group. Seventeen measurements were obtained from the tracing of PA X-ray cephalometric headfilms to evaluate the asymmetric characteristics and changes accdording to aging in UCLP. The obtained results were as follows. 1. Facial asymmetry in UCLP is variable(1.22-3.47 $mm/^{\circ}$) and the length from midsagitta1 reference line to maxillary 1st molar, to upper central incisor and the length of mandibular ramus showed significant asymmetry 2. Nasal septum and anterior nasal spine were deviated In the cleft side and the lower border of nasal cavity was 1ower in cleft side. 3. The deviation of nasal septum was continued significantly till after 14 years old.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.6
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• pp.492-498
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• 2009

We sought to evaluate the relationship between the mandibular canal and impacted mandibular third molars by using dental cone beam computed tomograph(CBCT) for third molar surgery. A total of 111 patients(177 teeth) offered the images through CBCT and panoramic radiography for the extraction of the mandibular third molars. In CBCT, the accurate relationship between the third molar and the mandibular canal were evaluated. In panoramic radiographies, we evaluated the impacted level and superimposition sign of the mandibular third molar with the mandibular canal, and also, the radiopacity of the white line in the canal. Data were statistically analyzed and estimated by $X^2$-test. In CBCT finding, high prevalence of contact between the mandibular canal and roots occured in the deep impacted third molars, narrowing mandibular canals, bending mandibular canals and cases where the radiopacity of white line of canals were "absence" on panoramic images. It showed statistical significance (P<0.05). When evaluating the mandibular canal and the roots through the panoramic radiography for third molar extraction, it could be difficult to diagnosis accurately. Thus, it is required to have an accurate diagnostic approach through CBCT that could evaluated the location between mandibular canal and root.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.1
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• pp.48-60
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• 2003

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the lower First Molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan). The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine(Zwick Z020, Zwick, Germany)was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 2.5mm depth and $12^{\circ}$ inclination was the highest (1789 N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength (1091 N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth. Size of fragment was affected by the amount of occlusal reduction.

• Journal of The Korean Dental Society of Anesthesiology
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• v.4 no.1 s.6
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• pp.13-16
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• 2004

Background: Articaine, a new amide-type local anesthetic, was recently commercially available in Korea. The purpose of this study was to compare the anesthetic efficacy between articaine HCl and lidocaine HCl for the surgical extraction of bilateral mandibular impacted third molars. Patients and Methods: Forty young and healthy patients with bilateral impacted third molars were selected with permission. Randomly, one side of impacted third molar was operated under local anesthesia using 4% articaine and the other side under 2% lidocaine after 1 or 2 week recovery time. Intraoperative pain was evaluated via 0-10 cm visual analog scale (VAS) by both the patient and operator immediately after the operation. After 1 day and 7 days, the complications of local anesthesia were checked. Results: The pain VAS scores in articaine group, evaluated by both the patient and operator, were lower than those in lidocaine group, but they were not statistically significant (P = 0.44 and 0.54, respectively). The incidence of complications of local anesthesia between articaine and lidocaine was similar. Conclusion: In this study, articaine showed at least equal efficacy compared to lidocaine. The further dose-controlled study with more pharmacokinetic parameters will be needed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.6
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• pp.474-480
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• 2005

We evaluated the need for prophylactic postoperative oral antibiotic medication in extraction of asymptomatic impacted mandibular third molars. All patient didn't show sign of pain, inflammation, swelling and trismus at the time of extraction. In the experimental group, oral antibiotic medication(Amoxicillin) was carried out for 5 days postoperatively. In the control group, the patients received no antibiotic medication. All groups didn't use antibiotic irrigation solution. Rule of group composition randomized. The surgical technique was the same in all cases. Parameters that were evaluated were infection, pain, facial swelling, trismus. We could not find any significant difference between the experimental and control groups.(P<0.05) The results of our study show that post operative oral prophylactic antibiotic medication after the extraction of impacted mandibular third molars does not contribute to less infection, pain, facial swelling and increased mouth opening after surgery. Therefore we suggest that prophylactic postoperative oral antibiotic medication is not needed in extraction of asymptomatic impacted mandibular third molars.

• Imaging Science in Dentistry
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• v.37 no.2
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• pp.103-110
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• 2007

Purpose: To examine the danger zone of mesial root of mandibular first molar of patient without extraction using CBCT (cone-beam computed tomography) to avoid the risk of root perforation. Materials and Methods: 20 mandibular first molars without caries and restorations were collected, CT images were obtained by CBCT ($PSR9000N^{TM}$, Asahi Roentgen Co., Japan), reformed and analyzed by V-work 5.0 (CyberMed Inc., Korea), Distance between canal orifice and furcation was measured. In cross sectional images at 3, 4 and 5 mm below the canal orifice, distal wall thickness of mesiobuccal canal (MB-D), distal wall thickness of mesiolingual canal (ML-D), distal wall thickness of central part (C-D), mesial wall thickness of mesiobuccal canal (MB-M) and mesial wall thickness of mesiolingual canal (ML-M) were measured, Results: The mean distance between the canal orifice and the furcation of the roots is 2.40 mm, Distal wall is found to be thinner than mesial wall. Mean dentinal wall thickness of distal wall is about 1 mm, The wall thickness is thinner as the distance from the canal orifice is farther. But significant differences are not noted between 4 mm and 5 mm in MB-D and C-D, MB-D is thinner than ML-D although the differences is not significant. Conclusion: The present study confirmed the anatomical weakness of distal surface of the coronal part of the mesial roots of mandibular first molar by CBCT and provided an anatomical guide line of wall thickness during endodontic treatment.

• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.91-99
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• 1986

In order to evaluate the community dental health level the actual health capacity of the lower-first permanent molar is suitable as a indicator for assessment. So we had surveyed decayed, missed and filled lower permanent first molar of 460 persons who were in the age from 20 to 29 in Iri City. The obtained results were as follows: 1. The DMFT indices of the lower first permancent molars showed in 1.40 in the age group of from 20 to 24 and 1.44 from 25 to 29. 2. The actual dental health capscities of the lower first permanent molars showed in 84.86% in the age group of from 20 to 24 and 81.03% from 25 to 29. 3. The DMF indices of the lower first permanent molars showed 15.15% in the age group of from 20 to 24 and 18.98% of from 25 to 29. 4. The DMF rates of the lower first permanent molars showed 85.66% in the age group of from 20 to 24 and 88.70% of from 25 to 29. 5. The DMF rates of the lower first permanent molars showed 70.00% in the age group of from 20 to 24 and 71.96% of from 25 to 29. 6. The DT rates of the lower first permanent molars showed 48.84% in the age group of from 20 to 24 and 39.55% of from 25 to 29. 7. The FT rates the lower first permanent molars showed 40.22% in the age group of from 20 to 24 and 43.98% of from 25 to 29. 8. The MT rates of the lower first permanent molars showed 10.94% in the age group of from 20 to 24 and 16.17% of from 25 to 29.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.3
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• pp.217-225
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• 2001

Any fracture passing through the socket of a teeth is compounded intraorally, even if the fracture is not displaced and the tooth is firm in its socket. Before the advent of antibiotic therapy the danger of infection in a compounded fracture posed severe problems in treatment. Infection is reduced by antibiotic therapy but prolonged use of antibiotics is not justified in an attempt to save a tooth which might eventually be sacrificed. There is still controversy in the management of third molar in mandibualr angle fracture, particulary in regard to their retention or removal at the time of fracture treatment. So we surveyed the 159 patients who were treated with open reduction of mandibular angle fracture containing third molar in fracture line, and compared with the postoperative infection rate depending on time intervals between injury and operation, eruption state of third molar, non-extraction or extraction of third molar related to eruption state, non-extraction or extraction of third molar related to condiition of third molar and its surrounding periodontium and were to propose treatment guidline of third molar in mandibular angle fracture The results obtained were as follows : 1. There were no statistical significance between the time from injury to operation and postoperative infection. 2. There were no statistical significance between eruption state of third molar and postoperative infection. 3. In case of retention of the third molar, there were no statistical significance between eruption state of third molar and postoperative infection, but in case of extraction, postoperative infection was high rate in complete impacted cases. 4. There were no statistical significance between non-extraction or extraction of third molar and postoperative infection depending on condition of third molar. There are no difference in infection rate statistically according to the time from injury to operation, eruption state and condition of third molar, but retention of third molar revealed lowered infection rate in completely impacted cases. By terms of the manegement of third molar, we should extract or preserve third molar in the line of the mandibular angle fracture according to possibility of infection.