• 대한치과의사협회지
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• 제21권12호통권175호
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• pp.1005-1010
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• 1983

To study the eruption process of the permanent tooth, esp., 1st molar, the author took 303 cases of oblique cephalogram (Male. 162 cases, Female: 141 cases) from age 3 to 8 yea old children, and observed the vertical change and axial change. The result were as follow: 1. The mesial end of upper 1st molar was closer to the occlusal plane than the distal, and they were erupting toward the occlusal plane by aging. In the case of lower 1st molar, the distal end was closer to the occlusal plane than the mesial and the occlusion showed the tendency to accord with the plane to be settled by aging. 2. Eruption rate of the upper and lower 1st permanent molar increased rapidly at 5 or 6 years of age. 3. Axial inclination of lower 1st permanent molar to the mandibular plane decreased gradually from 3 years of age, except for 6 years of age. There was some increase at 5 or 6 years of age.

• 대한치과의사협회지
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• 제50권6호
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• pp.322-328
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• 2012

Ectopic eruption of the permanent first molar is defined as the eruption of the tooth in an abnormal position or orientation. It may causes distal root resorption and premature exfoliation of the adjacent primary second molar and uncontrolled space loss is followed. Prolonged partial impaction of the permanent molar may also cause undetected caries or abscess formation of the neighbor teeth. The purpose of this paper is to provide a brief review regarding the etiology, classification, and different management techniques for correcting ectopic eruption of permanent first molar.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.416-422
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• 2017

PURPOSE. To investigate the effect of reducing tooth preparation and ceramic thickness on fracture resistance of lithium disilicate crowns. MATERIALS AND METHODS. Specimen preparation included a standard complete crown preparation of a typodont mandibular left first molar with an occlusal reduction of 2 mm, proximal/axial wall reduction of 1.5 mm, and 1.0 mm deep chamfer (Group A). Another typodont mandibular first molar was prepared with less tooth reduction: 1 mm occlusal and proximal/axial wall reduction and 0.8 mm chamfer (Group B). Twenty crowns were milled from each preparation corresponding to control group (n=5) and conditioned group of simultaneous thermal and mechanical loading in aqueous environment (n=15). All crowns were then loaded until fracture to determine the fracture load. RESULTS. The mean (SD) fracture load values (in Newton) for Group A were 2340 (83) and 2149 (649), and for Group B, 1752 (134) and 1054 (249) without and with fatigue, respectively. Reducing tooth preparation thickness significantly decreased fracture load of the crowns at baseline and after fatigue application. After fatigue, the mean fracture load statistically significantly decreased (P<.001) in Group B; however, it was not affected (P>.05) in Group A. CONCLUSION. Reducing the amount of tooth preparation by 0.5 mm on the occlusal and proximal/axial wall with a 0.8 mm chamfer significantly reduced fracture load of the restoration. Tooth reduction required for lithium disilicate crowns is a crucial factor for a long-term successful application of this all-ceramic system.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권2호
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• pp.86-90
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• 2023

Objectives: An ectopic tooth is a rare eruption of a tooth out of the normal dental apparatus and occurs commonly with the third molar. Thus, in this study, we reported a case series of ectopic teeth in rare jaw locations and highlight the associated pathology and our experience in the surgical management. Patients and Methods: All cases of ectopic tooth managed at the Department of Oral and Maxillofacial Surgery, University of Maiduguri Teaching Hospital from January 2011 to December 2020 were reviewed. The information retrieved includes biodata, location of the ectopic tooth, signs, symptoms, type of tooth and associated pathology, surgical approach and complications. Results: Ten cases of ectopic teeth were identified over the study period. This comprised 80.0% males with a mean age was 23.3 years. The antrum and lower border of the mandible accounted for 50.0% and 40.0% of the ectopic locations, respectively. Dentigerous cyst was the most associated pathology (70%) and usually presented with pain and swelling. Surgical intervention predominantly via the intraoral route was performed if indicated. Conclusion: Ectopic teeth are rare and not always associated with pathology. A high index of suspicion and radiological investigation are necessary for diagnosis. A more extensive multi-center study is however recommended to determine the prevalence of ectopic teeth other than the third molar.

• 구강회복응용과학지
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• 제17권4호
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• pp.257-274
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• 2001

To properly prepare teeth, dentists require a direct view of the working area and are often placed in a difficult position, moreover, a high proportion of dentists suffer from headache and back pain. Dentists who make use of the dental mirror and position their patients carefully to gain a proper view report less headache, pain and discomfort in the shoulders. It is recommended that dentists learn the "Home Position(H.P.)" which among the various "Random Position(R.P.)" methods, enables dentists to approach their patients in a stable posture. The purpose of this study was to compare tooth preparation in the H.P. and the R.P., and evaluate the clinical efficacy of the H.P.. Tooth preparation for a full cast crown was performed on the maxillary left 1st molar using the H.P. and the R.P., and the shapes of the prepared tooth surfaces at the two different operating positions were compared. The amount of occlusal reduction, marginal width, height, and axial taper were measured and analyzed. A T-test was performed separately to compare the results of the H.P. and the R.P. with respect to the accuracy of the corresponding tooth reduction. The results were as follows. ; 1. The amount of occlusal reduction was excessive on the mesiobuccal cusp(P<0.05), and deficient on the lingual cusp in the H.P.(P<0.01). In the R.P., this was excessive on the buccal cusp and deficient on the fossa and distolingual cusp(P<0.01). 2. The amounts of marginal width were excessive in all areas except on the lingual and mesial surfaces in the H.P. and lingual surface in the R.P.(P<0.01). 3. The marginal heights were achieved more accurately in the R.P. than the H.P.(P<0.01). 4. Axial surface taper was excessive in all areas in the H.P.(P<0.01). But the axial taper of measured areas was even, and tooth is more like to retain its original axis after reduction. In the R.P., axial surface taper was excessive on the mesial and buccal area, and deficient on the distolingual area(P<0.01), and therefore, the axis of the prepared teeth was tipped in the distolingual direction. 5. The times needed for preparation were 12 minutes and 49 seconds in the H.P., and 11 minutes and 35 seconds in the R.P., and the R.P. was statistically faster(P<0.01). The tooth preparation in the H.P. achieved its goal, in that it enabled the operator to make even tooth reduction. In conclusion, the H.P. system offers an improved method that can be used in clinic after specific training.

• Journal of Dental Anesthesia and Pain Medicine
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• 제17권2호
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• pp.121-127
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• 2017

Background: There are no studies regarding 4% articaine infiltration injection into the retro-molar area for an impacted lower third molar (LITM) surgery. This study aimed to evaluate the efficacy of infiltration using 1.7 ml (single cartridge: SC) of 4% articaine versus 3.4 ml (double cartridges: DC) of 4% articaine with 1:100,000 epinephrine in LITM surgery. Method: This study involved 30 healthy patients with symmetrical LITM. The patients were assigned to receive either a DC or SC of 4% articaine with 1:100,000 epinephrine as a local anesthetic for each operation. Onset, duration, profoundness, need for additional anesthetic administration, total volume of anesthetic used, vitality of the tooth, and pain score during operation were recorded. Results: The DC of 4 % articaine had a significantly higher success rate (83.3%) than did the SC (53.3%; P<0.05). The duration of soft tissue anesthesia was longer in the DC group. The intra-operative pain was higher in the SC group with a significant (P < 0.05) requirement for a supplementary local anesthetic. Conclusion: We concluded that using DC for the infiltration injection had a higher success rate, longer duration of anesthesia, less intra-operative pain, and a lower amount of additional anesthesia than SC in the surgical removal of LITM. We recommend that a DC of 4% articaine and a 1:100,000 epinephrine infiltration in the retro-molar region can be an alternative anesthetic for LITM surgery.

• 대한치과교정학회지
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• 제50권4호
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• pp.268-277
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• 2020

This case report demonstrates two different uprighting mechanics separately applied to mesially tipped mandibular first and second molars. The biomechanical considerations for application of these mechanisms are also discussed. For repositioning of the first molar, which was severely tipped and deeply impacted, a novel cantilever mechanics was used. The molar tube was bonded in the buccolingual direction to facilitate insertion of a cantilever from the buccal side. By twisting the distal end of the cantilever, sufficient uprighting moment was generated. The mesial end of the cantilever was hooked over the miniscrew placed between the canine and first premolar, which could prevent exertion of an intrusive force to the anterior portion of the dentition as a side effect. For repositioning of the second molar, an uprighting mechanics using a compression force with two step bends incorporated into a nickel-titanium archwire was employed. This generated an uprighting moment as well as a distal force acting on the tipped second molar to regain the lost space for the first molar and bring it into its normal position. This epoch-making uprighting mechanics could also minimize the extrusion of the molar, thereby preventing occlusal interference by increasing interocclusal clearance between the inferiorly placed two step bends and the antagonist tooth. Consequently, the two step bends could help prevent occlusal interference. After 2 years and 11 months of active treatment, a desirable Class I occlusion was successfully achieved without permanent tooth extraction.

• 대한소아치과학회지
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• 제48권2호
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• pp.229-236
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• 2021

하악 제1대구치의 맹출 장애는 매우 드물지만, 발생할 경우 교합 발육에 다양한 문제를 초래할 수 있으므로, 하악 제1대구치의 맹출 장애의 조기 진단과 치료는 매우 중요하다. 이번 연구의 목적은 맹출 장애를 가진 하악 제1대구치의 두 증례에 대한 치료 방법을 제시하는 것이다. 하악 제2유구치를 고정원으로 하는 cantilever-type의 spring을 추가한 견인 장치를 적용하여 매복된 제1대구치 견인을 시행했다. 따라서, 건전한 제2유구치가 존재하는 환자에서 이 장치가 짧은 시간 안에 매복된 하악 제1대구치의 정상적인 맹출을 유도할 수 있음을 확인 할 수 있었다.

• 대한소아치과학회지
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• 제39권4호
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• pp.404-411
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• 2012

치아의 매복은 맹출로 내의 물리적 장애물이나 치아의 비정상적 위치에 의해 발생한 치아 맹출의 정지로, 하악 제2대구치의 매복은 비교적 드물다. 매복된 하악 제2대구치는 우식, 치주염, 제1대구치 치근흡수 등을 유발하므로 조기 진단과 치료가 요구된다. 첫 번째 증례는 10세 남자 환자로 하악 양측 제2대구치의 매복을 구리선을 이용하여 치료하였다. 두 번째 증례는 12세 여자 환자로 구강검진 도중 하악 좌측 제2대구치의 매복이 발견되어 Humphrey 장치를 이용하여 치료하였다. 세 번째 증례는 17세 여자 환자로 하악 우측 소구치부에 식립한 미니 임플란트를 고정원으로 하는 uprighting spring을 이용하여 하악 우측 제2대구치의 매복을 치료하였다. 네 번째 증례는 18세 남자 환자로 매복된 하악 좌측 제2대구치에 부착한 교정용 버튼과 하악지에 식립한 미니 임플란트를 elastic thread로 연결하여 치료하였다.

• 치과방사선
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• 제22권2호
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• pp.185-193
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• 1992

경북대학병원 치과에 내원한 8세에서 27세까지의 환자 6,531명의 파노라마 X선사진에서 제3 대구치를 제외한 선천성 결손치, 제3대구치의 선천성 결손, 과잉치의 발생율, 성별분포, 호발 부위 및 수에 따른 분포를 조사하여 다음의 결과를 얻었다. 1. 제3대구치를 제외한 선천성 결손치의 발생율은 10.8%였으며, 남성이 44.6%, 여성이 55.4%였다. 하악 제2소구치가 23.2 %로 가장 많았으며, 상악 측절치 18.4%, 하악 측절치 18.3%, 상악 제2소구치 15.4%의 순으로 나타났다. 결손치의 수는 1개 인 경우가 48%로 가장 많았으며, 2개인 경우가 35.4%, 3개인 경우가 6.6%로 나타났다. 2. 제3대구치 선천성 결손의 발생율은 39.7%였으며, 남성이 48.6%, 여성이 51.4%였고, 상악 60.3%, 하악이 39.7%였다. 결손치의 수는 1개인 경우가 28.7%, 2개인 경우가 37.2%, 3개인 경우가 12.5%, 4개인 경우가 21.6%로 나타났다. 3. 과잉치의 발생율은 4.2%였으며, 남성이 65.7%, 여성이 34.3%였다. 상악 중절치부가 64.8%로 가장 많았으며, 상악 측절치부 13.2%, 상악 제3대구치 후방부 8.7%의 순으로 나타났다. 과잉치의 수는 1개인 경우가 79.9%로 가장 많았고, 2개인 경우가 18.9%, 3개인 경우가 1.2%로 나타났다.