• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.359-371
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• 2008

Purpose: The purpose of this study was to investigate the stress distribution in mandibular implant overdentures with telescopic crowns compared to bar attachment. Material and methods: Three-dimensional finite element models consisting of the mandibular bone, 4 implants, and primary bar-splinted superstructure or secondary splinted superstructure with telescopic crowns were created. Vertical and oblique loads were directed onto the occlusal areas of the superstructures to simulate the maximal intercuspal contacts and working contacts such as group function occlusion. Maximum stress and stress distribution were analysed in mandibular bone, implant abutments, and superstructures. Results: 1. In comparison of von Mises stress on mandibular bone, telescopic overdenture had a little lower stress values in vertical load and working side load except oblique load. In the mandible, the telescopic overdenture distributed more uniform stress than the bar overdenture. 2. In comparison of von Mises stress on implant abutments, telescopic overdenture had much lower stress values in all load conditions. In implant abutments, the telescopic overdenture distributed stress similar to the bar overdenture. Stress was concentrated on the distal surfaces of the posterior implant abutments in both mandibular overdentures. 3. In comparison of von Mises stress on superstructures, the telescopic overdenture had much more stress values in all load conditions. However, the telescopic overdenture distributed more uniform stress on superstructure than the bar overdenture. In the bar overdenture, stress was concentrated on each cental area of bar structures and connected area between implant abutments and bar structures. Conclusion: In the results of this study, the telescopic overdenture had lower stress values than the bar overdenture in mandibular bone and implant abutments, but more stress values in superstructures. However, if optimal material was selected in making superstructures, the telescopic overdenture was compared to the bar overdenture in stress distribution.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.3
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• pp.317-326
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• 2011

The mental foramen and anterior loop of the mandibular canal are important landmarks for mandibular surgical procedures. The purpose of this study was to analyze the shape and position of the mental foramen and anterior loop of the mandibular canal on the computed tomography (CT) images, and apply the results clinically. CT images of 96 patients (33 male, 36 female, age range 17~43 years, mean $24.6{\pm}4.99$ years) were enrolled. The horizontal and vertical position of the mental foramen, as well as the distance from the root apices were measured. The distance of the anterior loop of the mandibular canal to the root apices, and the buccal angle were measured. The mental foramen was found mostly below the second premolar observed in 81 cases (46.0%), between the first and second premolars in 67 cases (38.0%), and between the second premolar and first molar in 19 cases (10.2%). The mean distance between the mental foramen and the lower border of the mandible was $12.20{\pm}1.77$ mm, the mean distance between the mental foramen and root apex was $5.16{\pm}0.98$ mm. The mean distance of the anterior loop of the mandibular canal was $5.80{\pm}2.00$ mm. The buccal angle measured at $47.7{\pm}9.07^{\circ}$. The distance between the root apex and mental foramen measured as $5.16{\pm}0.98$ mm on panoramic radiography, and $6.2{\pm}3.07$ mm on CT. The mean distance between the mental foramen and mandibular canal was $5.39{\pm}1.62$ mm. When performing surgical procedures such as installing dental implants, it is important to minimize surgical trauma, especially the risk of damage to the mental nerve. To optimize the surgical outcome, a careful assessment of the shape and position of the mental foramen and the anterior loop of the mandibular canal must be made. CT images are useful for finding such anatomic structures.

• The korean journal of orthodontics
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• v.11 no.1
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• pp.7-15
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• 1981

Tooth movement by orthodontic force is based upon alveolar bone resorption at compression site and bone formation at tension site of tooth. The function of cyclic AMP is to participate not only in initial action of bone cells by mechanical forces but also in the continuous cellular response leading to bone remodeling. This experiment was performed to clarify the role of cyclic AMP in bone remodeling by mechanical forces. The orthodontic forces of about 80 gm and 100 gm were applied to the right canines of maxillary and mandibular bone, respectively, in cats, treated for periods of time ranging from one hour to 28 days. Alveolar bones were obtained from compression and tension sites surrounding tipping maxillary and mandibular canines as well as from contralateral control sites. The samples were extracted, boiled and homogenized, and the supernatants were assayed for cyclic AMP by a radioimmunoassay method. The results were as follows: 1. The orthodontic movement of canines was increased to the end of experimental period and the action of orthodontic forces on tooth movement was more effective in maxillary canine. 2. The cyclic AMP levels of alveolar bones in compression and tension sites initially decreased, then increased and remained elevated to the end of experiment. The differences of the cyclic AMP levels between treated sites and non-treated sites were gradually increased. 3. The cyclic AMP levels in treated sites of mandibular alveolar bone was higher than that of maxillary alveolar bone.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.4
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• pp.275-282
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• 2001

Centric relation is defined the horizontal position between maxilla and mandible when condylar head of mandible is positioned adequately in mandibular fossa. The most recent concept of centric relation position is defined as the mandibular position in which the condyles are in their most superoanterior position in the articular fossa, resting against the posterior slope of the articular eminences, with the articular disk properly interposed. To be suitable as a reference point during occlusal management, a mandibular position of centric relation has to be functionally acceptable to the patient and clinically reproducible and achievable during everyday practice. There are numerous methods for determination of centric relation, and in this study we used three of them, Gothic arch tracing(Group I), leaf gauge(Group II), and anterior jig(Group III). The subjects were 10, 8 men and 2 women, age-ranged from 23 to 26 years old, had no prosthetics in thier mouth, and had no sign and symptom of temporomandibular disorders. We gained three occlusal records using each method, and then the degree of the reproducibility was examined with split cast technique. In this study the reproducibility of centric relation using split cast technique was greater in the order of Group I(mean 1.6), Group II(mean 1.4), and Group III(mean 1.3), but there was no significant differences among them statistically(p>0.05).

• Journal of Oral Medicine and Pain
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• v.16 no.1
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• pp.85-93
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• 1991

In this study, 88 dental students were examined to evaluate the relationship between occlusal states and TM disorders for the epidemiologic study of TM disorders. The clinical evaluation were composed of mandibular movement, TMJ noise, occlusal states and muscle palpation. The following results were disclosed. 1. The frequencies of pain on mandibular movement were 3.4% on maximum opening, 1.13% on protrusion and no pain on laterotrusion. 2. The frequencies on TMJ sound were 21.6% in click, 1.13% in crepitus. 3. The frequency of tenderness on palpation was 12.5% on extra oral, intraoral and neck muscles, tenderness on palpation of TMJ capsule were reported 5 cases, and 4 of them were female. 4. The distribution of Angle's classification was found 79.5% in class I, 4.5% in clasII-div.1 and 15.9% in class III. There was no significant differences on TM disorders between Angles classifications. 5. There was no significant differences on TM disorders between the subjects of canine guided occlusion and group function occlusion, and also for the differences between the subjects of nonworking side interferences and no interferences on laterotrusion. 6. There was no significant differences on TM disorders between the subjects of anterior teeth trauma in C.C. and no anterior teeth trauma, but there were significant differences between the subjects of posterior protrusive contact and no posterior protrusive contact.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.1
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• pp.24-30
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• 2002

The facial patterns were expressed by the interrelation of variable factors such as heredity, function and environment. Such variable factors have an effect on the growth and development of maxillofacial bones. The malocclusions with skeletal discrepancies are caused by abnormal forms, sizes and positions of cranial base, maxilla and mandible. For the proper diagnosis and treatment planning, the analysis of such structures is necessary. Lateral cephalograms of 54 adults with class III malocclusion patients (test group) and 61 adults with normal occlusion (control group) were analyzed. Anteroposterior relations and sizes of cranial base, maxilla, mandible were estimated to compare with those of normal ones. In test group, the anterior cranial base length was within normal range, but posterior cranial base, maxilla and mandibular body were longer than those in control group, significantly. Based on the cranial base, the location of maxilla in test group was normal, but the location of mandible was more anterior than that in control. Based on the maxilla, the location of mandible was more anterior in test group than that in control. Both mandibular body and ramus anteroposterior lengths in test group were larger than those in control. Both mandibular plane angle and upper gonial angle were within normal range, but lower gonial angle was significantly high in test group.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.1
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• pp.73-79
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• 2006

The management of mandibular prognathism and retrognathism was revoluted by the advent of the technique of bilateral sagittal split ramus osteotomy(BSSRO) as described by Obwegeser and Trauner in 1957. The BSSRO of the mandible has been used for nearly 50 years and has undergone numerous modifications and improvements. Most patients, treated by this surgical operation, express their satisfaction with improved facial esthetics, masticatory function and others. But several complications associated with BSSRO may appear. Especially among them, facial nerve palsy following BSSRO is rare but serious problem. We treated for facial nerve palsy following BSSRO by physical therapy, steroid therapy and surgical intervention and then the result was favorable. Therefore we would like to report a case about a patient with facial nerve palsy after BSSRO with a review of the literatures.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.53-65
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• 1984

The purpose of this study was to investigate the histopathological change and adaptation process of the mandibular joint of the rat by muscle alteration. For this study, one hundred and twenty eight rats of 25 - and 60 - day old of age were used. Unilateral and bilateral detachment, with anterior positioning of the Masseter muscle, was performed under anesthesia. The animal was sacrified 10, 20, 50, 80 days postoperatively. This alteration in muscle function led to change in neuromuscular activity and demonstrated the adaptive nature of the condyle cartilage to functional demand. The results were as follows : 1. In the right muscle detached group, operated at 25 days of age, marked decrease on the chondroblastic zone was found in the condyle head on the right side of animals examined 10 days postoperatively. Comparing with the control group, no difference was found on the chondroblastic zone in the condylar head of animals examined 20, 50 and 80 days postoperatively. 2. In the bilateral muscle detached group, operated at 25 days of age, the chondroblastic zone was slightly decreased in the anterior parts of condylar head of animals examined 10 days postoperatively. 3. In the unilateral and bilateral muscle detached group, operated at 60 days of age, no significant change was found in the mandibular joint regardless of the post operative experimental periods. 4. Under Toluidine blue staining, slightly decreased metachromasia was found in the condyle head on the right side of unilateral experimental animals, operated at 25 days of age and examined 10 days postoperatively. 5. Under Masson's trichrome staining, increased metachromasia was found in the condyle head on the right side of unilateral experimental animals, operated at 25 days of age and examined 10 days postoperatively. In summary, the condyle of the rat could respond to changes in neuromuscular activity depend on the level of maturation of the tissue, because the endochondral bone formation of the condyle of the rat was almost ended within 3 months.

• Journal of Oral Medicine and Pain
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• v.24 no.1
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• pp.37-47
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• 1999

This study was performed to investigate the factors related to vibration of temporomandibular joint during mandibular opening movement. For this study, 144 patients with temporomandibular disorders were randomly selected. Angle's classification, lateral guidance pattern, range of maximal mouth opening, preferred chewing side, and affected side were investigated clinically. Mandibular torque rotational movement during opening was recorded with $BioEGN^{(R)}$ and vibration of temporomandibular joint during opening was recorded with $Sonopak^{(R)}$. After clinical diagnosis was made, visual analogue scale(VAS) was used for evaluation of clinical progress of the subject's chief complaints. The author calculated VAS treatment index(VAS Ti) from the record of VAS. The more VAS Ti was, the less remission of subjective symptom was, The data were analyzed with SAS/Stat program and the results of this study were as follows: 1. There were no significant difference in all the variables of joint vibration by age and sex. 2. Integral and peak amplitude in patients of Angle's class I were higher than those of class II or III patients. Integral in patients of group function was higher than that in patients of canine guidance or other types of lateral excursion. 3. As to Angle's classification or lateral guidance type, there were almost not significant difference between subgroup of same class or type and subgroup of different class or type on both sides. And there were also almost not difference between one side and the other side related to preferred chewing side or affected side. 4. Patients with disk displacement with reduction showed higher value of integral and peak amplitude than any other patients. 5. Joint vibration variables significantly correlated with VAS Ti of pain. with clinical range of mouth opening, and with ingredients of mandibular torque rotational movement.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.184-191
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• 2014

In the mandibular posterior molar area, ridge deficiency is an unfortunate obstacle in the field of implant dentistry. Many techniques are available to rebuild the deficient ridge. Selection and necessity of these techniques are associated with significant morbidity and often require a second surgical site. With the advent of guided bone regeneration (GBR), one may now graft the deficient ridge with decreased morbidity and without a second surgical site. In this case, guided bone regeneration procedures were performed with a combination of allograft, xenograft, and alloplast, excepting autogerous bone at severe defected mandibular alveolar ridge and then placed to the implant successfully. We report that implant placement were good in two cases.