• Journal of the Korean Chemical Society
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• v.8 no.4
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• pp.183-187
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• 1964

The excess molar surface entropies of each surface layers are calculated applying the modified significant structure theory of liquid. The calculated excess molar surface entropy for the first top surface layer is slightly greater than the entropy of surface formation of ideal molecules,$^5$ the latter is equal to Rln2. The excess entropy for the second surface layer is small and that for the third layer is negligible at low temperatures. The surface tensions of argon, nitrogen, methane, benzene and halogens are calculated applying the modified significant structure theory of liquid.

• 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

• Journal of The Korean Dental Society of Anesthesiology
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• v.10 no.1
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• pp.27-33
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• 2010

The gag reflex is a physiologic reaction which safeguards the airway from foreign bodies. But, an exaggerated gag reflex can be a severe limitation to a patient's ability to accept dental care and for a clinician's ability to provide it. The overactive gag reflex can be due to psychological factors or physiological factors, or both. Psychological factors can include fear of loss of control and past traumatic experiences. A 58-year-old man, scheduled for extraction of left upper second molar, left lower second and third molar and implantation of left upper second molar, and left lower second molar had no specific underlying medical problems. He had exaggerated gag reflex. Dental treatment was successfully performed using intravenous sedation. Intravenous sedation with midazolam and propofol was a useful management technique for reflex control during dental treatment extended to the posterior regions in the oral cavity.

• Journal of Periodontal and Implant Science
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• v.38 no.1
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• pp.103-108
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• 2008

Purpose: Studies reported controversial results about prognosis of root resection with 0%-38% failure rate. The purpose of this study is to consider clinical efficacy of root resection. Materials and Methods: This study reported three cases of root resection which were performed on different sites. In first case, lower right first molar showed pus discharge and 7 mm of probing pocket depth. It was diagnosed as fracture of mesial root. Hemisection of mesial root was performed. In second case, upper right first molar showed severe bone loss on disto-buccal root and 7 mm of probing pocket. Resection of disto-buccal root was performed In third case, lower left second molar showed severe bone loss on distal root including apex and 15mm of probing pocket depth. Hemisection of distal root was performed. Result: In these three cases of root resection, compromised molars were treated successfully and conserved. Conclusion: Root resection is a successful procedure treating compromised multi-rooted teeth and conserving teeth when proper case selection is performed.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.1
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• pp.29-35
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• 2017

Background: No study has compared lidocaine with articaine, each at a concentration of 4% and combined with epinephrine. The purpose of this study was to compare the effectiveness of 4% lidocaine with that of 4% articaine, with a concentration of 1:100,000 epinephrine added to each, in an inferior alveolar nerve block for surgery on impacted lower third molars. Method: This study was conducted at the Faculty of Dentistry, Mahidol University in Bangkok, Thailand. The randomized, single-blind, comparative split-mouth study was carried out in patients with symmetrically impacted lower third molars, as identified on panoramic radiographs. Each patient underwent surgery for the removal of the lower third molars by the same surgeon under local anesthesia at two separate visits, 3 weeks apart. The onset and duration of local anesthesia, intra-operative pain, surgical duration, and number of additional anesthetics administered were recorded. Results: The subjective and objective onset of action for the local anesthetics showed statistically significant differences (P < 0.05). However, the intra-operative pain, surgical duration, duration of local anesthesia, and number of additional anesthetics administered did not show statistically significant differences. Conclusion: The use of 4% articaine for the inferior alveolar nerve block was clinically more effective in the onset of subjective and objective anesthesia as compared with the use of 4% lidocaine. Based on the pain scores from the visual analogue scale, 4% lidocaine provided more analgesia during the procedure, and patients noted less intra-operative pain than with 4% articaine; however, the difference was not clinically significant.

• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.1
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• pp.9-17
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• 2020

Background: This study aimed to compare the pain levels during anesthesia and the efficacy of the QuickSleeper intraosseous (IO) injection system and conventional inferior alveolar nerve block (IANB) in impacted mandibular third molar surgery. Methods: This prospective randomized clinical trial included 30 patients (16 women, 14 men) with bilateral symmetrical impacted mandibular third molars. Thirty subjects randomly received either the IO injection or conventional IANB at two successive appointments. A split-mouth design was used in which each patient underwent treatment of a tooth with one of the techniques and treatment of the homologous contralateral tooth with the other technique. The subjects received 1.8 mL of 2% articaine. Subjects' demographic data, pain levels during anesthesia induction, tooth extractions, and mouth opening on postoperative first, third, and seventh days were recorded. Pain assessment ratings were recorded using the 100-mm visual analog scale. The latency and duration of the anesthetic effect, complications, and operation duration were also analyzed in this study. The duration of anesthetic effect was considered using an electric pulp test and by probing the soft tissue with an explorer. Results: Thirty patients aged between 18 and 47 years (mean age, 25 years) were included in this study. The IO injection was significantly less painful with lesser soft tissue numbness and quicker onset of anesthesia and lingual mucosa anesthesia with single needle penetration than conventional IANB. Moreover, 19 out of 30 patients (63%) preferred transcortical anesthesia. Mouth opening on postoperative first day was significantly better with intraosseous injection than with conventional IANB (P = 0.013). Conclusion: The IO anesthetic system is a good alternative to IANB for extraction of the third molar with less pain during anesthesia induction and sufficient depth of anesthesia for the surgical procedure.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.6
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• pp.309-315
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• 2019

Objectives: The aim of this study was to evaluate the validity of the existing classification and difficulty index of impacted mandibular third molars in clinical situations and propose a more practical classification system. Materials and Methods: This study included 204 impacted mandibular third molars in 154 patients; panoramic x-ray images were obtained before tooth extraction. Factors including age, sex, and pattern of impaction were investigated. All impacted third molars were classified and scored for spatial relationship (1-5 points), depth (1-4 points), and ramus relationship (1-3 points). All variables were measured twice by the same observer at a minimum interval of one month. Finally, the difficulty index was defined based on the total points scored as slightly difficult (3-4 points), moderately difficult (5-7 points), very difficult (8-10 points), and extremely difficult (11-12 points). Results: The strength of agreement of the total points scored and difficulty index were 0.855 and 0.746, respectively. Most cases were classified as moderately difficult (73.0%). Although only 13 out of 204 cases (6.4%) were classified as extremely difficult, patients classified as extremely difficult were the oldest (P<0.05). Conclusion: For difficulty classification, the authors propose one more difficult category beyond the existing three-step difficulty index: the clinician should consider the patient's age in the difficulty index evaluation.

• Journal of Korean Dental Science
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• v.3 no.2
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• pp.4-11
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• 2010

Purpose: This study aimed at examining the thickness of lateral cortical bone in the mandibular posterior body and the location of the inferior alveolar nerve canal as well as investigating the clinically viable bone grafting site(s) and proper thickness of the bone grafts. Subjects and Methods: The study enrolled a total of 49 patients who visited the Department of Oral and Maxillofacial Surgery at Kyung Hee University Dental Hospital to have their lower third molar extracted and received cone beam computed tomography (CBCT) examinations. Their CBCT data were used for the study. The thickness of lateral cortical bone and the location of inferior alveolar nerve canal were each measured from the buccal midpoint of the patients' lower first molar to the mandibular ramus area in the occlusal plane of the molar area. Results: Except in the external oblique ridge and alveolar ridge, all measured areas exhibited the greatest cortical bone thickness near the lower second molar area and the smallest cortical bone thickness in the retromolar area. The inferior alveolar nerve canal was found to be located in the innermost site near the lower second molar area compared to other areas. In addition, the greatest thickness of the trabecular bone was found between the inferior alveolar nerve canal and the lateral cortical bone. Conclusions: In actual clinical settings involving bone harvesting in the posterior mandibular body, clinicians are advised to avoid locating the osteotomy line in the retromolar area to help protect the inferior alveolar nerve canal from damage. Harvesting the bone near the lower second molar area is judged to be the proper way of securing cortical bone with the greatest thickness.

• Journal of Korean Dental Science
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• v.9 no.1
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• pp.42-48
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• 2016

Prophylactic removal of impacted third molars is a common procedure in dentistry, but the necessity of routine extraction is still controversial. When impacted third molars caused severe apical root resorption of the second molars, orthodontic traction of the third molars after extraction of the damaged second molars could minimize alveolar bone defect and preserve the patient's natural teeth. By well-planned orthodontic treatment, functional occlusion was established avoiding extraction of the impacted teeth and eliminating the possibility of a large bone defect after extraction.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.5
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• pp.251-258
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• 2016

Objectives: The aim of this retrospective study was to investigate factors associated with increased difficulty in the surgical extraction of impacted lower third molars and to improve identification of difficult cases. Materials and Methods: A total of 680 patients who required 762 surgical extractions of impacted lower third molars from 2009 to 2014 were enrolled in the study. Demographic factors, clinical factors, radiographic factors, surgical extraction difficulty, and presumed causes of difficulty were collected. Data were statistically analyzed using IBM SPSS Statistics version 23. Results: Age, sex, depth of impaction, and blurred radiographic image influenced difficulty in surgical extraction. The position of the impacted tooth influenced surgical difficulty, especially when it was accompanied by other factors. Conclusion: It is challenging to design a reliable and practical instrument to predict difficulty in surgical extraction of impacted lower third molars. To identify very difficult cases, root investigation using computed tomography is advised when impacted tooth position suggests difficult extraction.