• Journal of Periodontal and Implant Science
• /
• v.36 no.2
• /
• pp.473-488
• /
• 2006

Adequate bone quality and stress distribution to the bone are of decisive importance for implant success. Even though the success rates of dental implants have been high, implant failures do occur. Overloading has been identified as a primary factor behind dental implant failure. The purpose of this study was to theoretically investigate the effect of two types of implants on the stress distribution in poor bone quality. Employing the finite element method, the study modeled a 4.1 mm diameter, 12.0 mm length implant placed in cortical or spongeous bone. A static loading of lOON was applied at the occlusal surface at 0, 30 degrees angle to the vertical axis of the implant. von Mises stresses concentrations in the supporting bone were analyzed with finite element analysis program. The results were as follows; 1. The stresses at the marginal bone were higher under buccal oblique load(30 degrees off of the long axis) than under vertical load. 2. Under buccal oblique load, the stresses were higher at the lingual marginal bone than at the buccal marginal bone, and the differences were almost the same. 3, Under vertical and oblique load, the stress was the highest at the marginal bone and lowest at the bone around apical portions of implant in cortical bone. 4, Under vertical load, Model 1 showed more effective stress distribution than Model 2 irrespective of bone types. On the other hand, Model 2 showed lower stress concentration than Model 1 under buccal oblique load.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.19 no.3
• /
• pp.153-168
• /
• 2003

It is very important to arrange the artificial teeth correctly in bucco-lingual (labio- lingual) relation in reconstrcting dentition. Although many anatomic landmarks and techniques have been reported over the years, they are based on westerns. So this study was performd to examine the horizontal relations of mandibular teeth in Korean dentulous adults. 200 volunteers(mean age 22.9) who had natural dentition were selected. The impressions were taken with irreversible hydrocolloid impression material and mandibular study models were fabricated using class I dental stone. Then they were measured with 3-dimensional measuring device specially designed for this study. The results were as follows ; It is better to consider the lingual cusps of the lower posterior teeth as a guide than the linguoaxial surfaces of the lower posterior teeth, arranging the lower posterior teeth buccally to the line which starts from the mesial aspect of the lower canine and continue backward to the lingual aspect of the retromolar pad. It is better to arrange the fossae of the lower posterior teeth buccally to the line which starts from the cusp tip of the lower canine and continue backward to the top of the retromolar pad. The positions of the lower posterior teeth in the denture-bearing area ; considering the fossa as a guide, the 2nd premolar was positioned in center. considering the buccal cusp as a guide, the 1st molar and the 2nd molar were positioned in center. the distance ratio(d/a) was incresed constantly from the lower canine to the 2nd molar d ; the distance between the buccal vestibule(the lowest point) and the buccal cusp tips of the lower posterior teeth. a ; the distance between the buccal vestibule(the lowest point) and the lingual vestibule(the lowest point). The lower canine was positioned lingually($0.11{\pm}0.13$) than the labial vestibule, and the central incisor and the lateral incisor were positioned almost in the imaginary perpendicular plane of the labial vestibule(the lowest point).

• Restorative Dentistry and Endodontics
• /
• v.7 no.1
• /
• pp.25-31
• /
• 1981

One of the most important factors for successful endodontic therapy is an accurate length determination of physiological root apex. Some methods suggested for the measurement of root canal length, include digital-tactile sense and roentgenographic technique with measuring wire, scale and grid. But these methods do not derermine an accurate working length to physiological root apex. Recently electronic measuring devices are used to locate the physiological root apex in root canal length determination and these devices are accepted as an effective apparatus. The 89 patients (116 teeth, 144 canals) among the out-patients of Yonsei University Dental Infirmary, who had had an endodontic treatment in the Department of Operative Dentistry, were measured by the Root-Canal Meter$^{(R)}$ as an electronic device, and radiographs to determine the distribution and location of physiological root apex, then the following results were made: (1) Range of ${\pm}$1mm from the radiographic root apex were present in 88.88% (128 canals) of the subjects. (2) Physiological root apex and radiographic root apex were coincided in 31.94% (46 canals) of the subjects. (3) The actual length of the physiological root apex of the teeth were as follow; A : in the maxillary central incisor : 0.46mm B : in the maxillary lateral incisor : 0.44mm C : in the maxillary canine : 0.44mm D : in the maxillary 1st premolar : a) Buccal : 0.59mm b) Lingual : 0.34mm E : in the maxillary 2nd premolar : 0.54mm F : in the maxillary 1st molar : a) Mesio-buccal : 0.50mm b) Disto-buccal : 0.42mm c) Lingual : 0.56mm G : in the mandibular central incisor : 0.62mm H : in the mandibular lateral incisor : 0.45mm in the mandibular canine : 0.54mm J : in the mandibular 1st premolar : 0.47mm K : in the mandibular 2nd premolar : 0.34mm L : in the mandibular 1st molar : a) Mesio-buccal : 0.54mm b) Mesio-lingual : 0.31mm c) Distal : 0.37mm.

• Journal of Dental Anesthesia and Pain Medicine
• /
• v.19 no.1
• /
• pp.45-54
• /
• 2019

Background: Profound anesthesia with adequate duration is required in periodontal flap surgery, which involves the manipulation of both hard and soft tissues. The anterior middle superior alveolar (AMSA) injection may be an alternative to multiple injections required for this purpose in the maxilla. The present study aimed to assess the effectiveness of AMSA injection using computer-controlled local anesthetic delivery (CCLAD) system to anesthetize buccal hard tissue (BHT), buccal soft tissue (BST), palatal hard tissue (PHT), and palatal soft tissue (PST) around the maxillary teeth. Methods: Thirty-five patients who were indicated for open flap debridement in a whole maxillary quadrant were given AMSA injection using the CCLAD. The effectiveness of anesthesia was evaluated using subjective and objective parameters around each tooth. Supraperiosteal infiltrations were administered to complete the surgery wherever the AMSA injection was ineffective. Results: The AMSA injection was more effective on the palatal tissues than on the buccal tissues, as 94.14% of PST and 87.89% of PHT sites were anesthetized compared to 49.22% and 43.75% of BHT and BST sites, respectively. There was no significant difference in the frequency of anesthesia around the anterior and posterior teeth. The PHT was significantly more anesthetized (P = 0.003) in males than in females. Conclusions: The AMSA injection using CCLAD is highly effective on palatal tissues and could be used as a first-line anesthesia for periodontal flap surgery. However, its effect on buccal tissues is less predictable, with supraperiosteal infiltration often required to supplement the AMSA injection.

• The korean journal of orthodontics
• /
• v.51 no.1
• /
• pp.23-31
• /
• 2021

Objective: To evaluate the mandibular buccal shelf (MBS) in terms of the angulation and bone depth and thickness according to sex, age, and sagittal and vertical skeletal patterns in a Colombian population using cone-beam computed tomography (CBCT). Accordingly, the optimal site for miniscrew insertion in this area was determined. Methods: This descriptive, retrospective study included 64 hemi-arches of 34 patients. On CBCT images, the angulation, buccal bone depth (4 and 6 mm from the cementoenamel junction [CEJ] of MBS), and buccal bone thickness (6 and 11 mm from the CEJ of MBS) were measured at the mesial and distal roots of the mandibular first and second molars. Results: There were no statistically significant differences in the angulation, depth, and thickness of MBS between male and female patients. The values for the bone around the distal root of the mandibular second molar were significantly greater than the other values. The osseous characteristics were significantly better in participants aged 16-24 years. Class III patients exhibited the best osseous characteristics, with the bone depth at 6 mm being significantly different from that in Class I and Class II patients. Although values tended to be greater in patients with low angles, the difference was not statistically significant. Conclusions: MBS provides an optimal bone surface for miniscrew insertion, with better osseous characteristics at the distal root of the mandibular second molar, 4 mm from CEJ. Adolescent patients, Class III patients, and patients with a low angle exhibit the most favorable osseous characteristics in the MBS area.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.46 no.6
• /
• pp.403-408
• /
• 2020

Objectives: Appropriate and accurate local anesthetic (LA) techniques are indispensable in the field of oral and maxillofacial surgery to obtain a satisfactory outcome for both the operating surgeon and the patient. When used alone, the inferior alveolar nerve block (IANB) technique requires supplemental injections like long buccal nerve block for extraction of mandibular molars leading to multiple traumatic experiences for the patient. The aim of this study was to anesthetize the inferior alveolar, lingual, and long buccal nerves with single-needle penetration requiring a minimal skillset such as administering a conventional IANB through introduction of the Benny Joseph technique for extraction of mandibular molars. Materials and Methods: This was a prospective study conducted in the Department of Oral and Maxillofacial Surgery, Kunhitharuvai Memorial Charitable Trust (KMCT) Dental College, Calicut, India. The duration of the study was 6 months, from June to November 2017, with a maximum sample size of 616 cases. The LA solution was 2% lignocaine with 1:100,000 adrenaline. The patients were selected from a population in the range of 20 to 40 years of age who reported to the outpatient department for routine dental extraction of normally positioned mandibular right or left first or second molars. Results: Of the 616 patients, 42 patients (6.8%) required re-anesthetization, a success rate of 93.2%. There were no complications such as hematoma formation, trismus, positive aspiration, and nerve injuries. None of the cases required re-anesthetization in the perioperative period. Conclusion: The Benny Joseph technique can be employed and is effective compared with conventional IANB techniques by reducing trauma to the patient and also requires less technique sensitivity.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.17 no.4
• /
• pp.283-305
• /
• 2001

The purpose of this study was to analyze the stress distribution of condylar regions and edentulous mandible with implant-supported cantilever prostheses on the certain conditions, such as amount of load, location of load, direction of load, fixation or non-fixation on the condylar regions. Three dimensional finite element analysis was used for this study. FEM model was created by using commercial software, ANSYS(Swanson, Inc., U.S.A.). Fixed model which was fixed on the condylar regions was modeled with 74323 elements and 15387 nodes and spring model which was sprung on the condylar regions was modeled with 75020 elements and 15887 nodes. Six Br${\aa}$nemark implants with 3.75 mm diameter and 13 mm length were incorporated in the models. The placement was 4.4 mm from the midline for the first implant; the other two in each quardrant were 6.5 mm apart. The stress distribution on each model through the designed mandible was evaluated under 500N vertical load, 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. The load points were at 0 mm, 10 mm, 20 mm along the cantilever prostheses from the center of the distal fixture. The results were as follows; 1. The stress distribution of condylar regions between two models showed conspicuous differences. Fixed model showed conspicuous stress concentration on the condylar regions than spring model under vertical load only. On the other hand, spring model showed conspicuous stress concentration on the condylar regions than fixed model under 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. 2. Fixed model showed stress concentration on the posterior and mesial side of working and balancing condylar necks but spring model showed stress concentration on the posterior and mesial side of working condylar neck and the posterior and lateral side of balancing condylar neck under vertical load. 3. Fixed model showed stress concentration on the posterior and lateral side of working condylar neck and the anterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior sides of working and balancing condylar necks under horizontal load linguobuccally. 4. Fixed model showed stress concentration on the posterior side of working condylar neck and the posterior and lateral side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 20 degree oblique load. 5. Fixed model showed stress concentration on the anterior and lateral side of working condylar neck and the posterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 45 degree oblique load.. 6. The stress distribution of bone around implants between two models revealed difference slightly. In general, magnitude of Von Mises stress was the greatest at the bone around the most distal implant and the progressive decrease more and more mesially. Under vertical load, the stress values were similar between implant neck and superstructure vertically, besides the greatest on the distal side horizontally. 7. Under horizontal load linguobuccally, buccal 20 degree oblique load and buccal 45 degree oblique load, the stress values were the greatest on the implant neck vertically, and great on the labial and lingual sides horizontally. After all, it was considered that spring model was an indispensable condition for the comprehension of the stress distributions of condylar regions.

• Korean Journal of Head & Neck Oncology
• /
• v.36 no.2
• /
• pp.69-72
• /
• 2020

We report a surgically challenging case of a large lipoma located from the temple, across the zygomatic region to the buccal area, resembling two different masses. An 82-year-old man presented with two persistently growing soft masses at his left temple and cheek. A computed tomographic scan revealed a single large radiolucent mass extending from the submuscular layer of the left temple crossing beneath the zygomatic arch to the buccal region, rather than two individual masses. Excision was performed through upper gingivobuccal and temporal incisions. The mass was dissected through both incisions, cut in half, and extracted from both sides. No complications were observed. The biopsy result was consistent with a lipoma. Four months later, the scars were inconspicuous, and the patient was satisfied. Considering the size, shape, and location, this is a rare and intriguing case. The bi-directional approach allowed for successful total excision without any complications, leaving inconspicuous scars.

• Animal Systematics, Evolution and Diversity
• /
• v.28 no.3
• /
• pp.149-160
• /
• 2012

Heterotrichous ciliates were isolated from marine and brackish habitats in Korea, and their morphology, infraciliature and morphometrical characters were investigated using silver impregnated methods. These three Condylostoma species were identified as Condylostoma curva Burkovsky, 1970, C. minutum Bullington, 1940 and C. spatiosum Ozaki and Yagiu in Yagiu, 1944. The species of Condylostoma based on morphology are highly variable in most of characters and distinguished as following. Condylostoma curva is oval to elongate ellipsoidal, size about $245{\times}100{\mu}m$ in vivo, and conspicuously dark greenish brown with cortical granules on their surface, buccal cavity relatively large about 40% of body length, 5-11 macronuclear nodules, 4-8 frontal cirri serially arranged and 22-38 somatic kineties. Condylostoma minutum is elongate ellipsoidal and the size about $310{\times}55{\mu}m$ in vivo, buccal field about 35% of body length, 12-20 macronuclear nodules, adoral zone consisted of 82-107 membranelles, large and long one frontal cirrus and 38-44 somatic kineties. Condylostoma spatiosum is large elongate ellipsoidal, size about $670{\times}105{\mu}m$ in vivo, buccal cavity about 25% of body length, 11-25 macronuclear nodules, 111-144 adoral membranelles, membrane-like 2 frontal cirri, 49-74 somatic kineties. These three Condylostoma species are described here for the first time in Korea.

• Journal of Oral Medicine and Pain
• /
• v.20 no.2
• /
• pp.449-459
• /
• 1995

To investigate the relationship between recurrent aphthous ulcer and oral mucosal keratinization, exfoliative cytology in buccal mucosa, lip mucosa, tongue mucosa were performed on 25 recurrent aphthous ulcer patients and 25 controls whose age ranged from 10 to 65. Keratinization cell ratio was then measured. The results were as follows : 1. Yellow cell ratio in the control group was more than that in the patient group in buccal mucosa, lip mucosa, tongue mucosa. Red cell ratio in the control group was more than that in the patient group in lip mucosa. Blue cell ratio in the patient group was more than that in control group in all regions( p(0.01) 2. In the comparison by sex, the patient group showed no significant difference in all site but, the control group showed different results according to the site; males were more than females in yellow cell, but less than females in red cell Females were more than males in yellow cell, but less than males in red cell. 3. In the comparison by age, patient group showed no significant difference in all site, but the control group showed significantly high yellow cell ratio in buccal and tongue mucosa over the age of 50. In conclusion, there was close relationship between recurrent aphthous ulcer and decreased oral mucosal keratinization. In other words, reduced oral mucosal keratinization must be recommended for prevention of recurrent aphthous ulcer.