• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.523-534
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• 1996

This study was to investigate the horizontal & vertical bone change pattern when using cervical headgear in Class II malocclusion of growing children and compared the skeletal features between the group with increased lower facial height and the group without increase in lower facial height. The results are as follows ; 1. Forward growth of maxilla was inhibited, downward tipping of anterior palatal plane could be seen and distal movement of maxillary first molar was observed. 2. There was relative forward movement of Mandible against the Maxillary cranial base, and relative forward movement of mandibular 1st molar against the Maxilla and vertical increase due to alveolar growth of Mandible. 3. There was significant increase in anterior and posterior facial heights but the ratio of facial height showed no significant difference. 4. The group with increased lower facial height has shorter ramus length, than the smaller palatal plane angle, and more distal movement of Maxillary 1st molar than the group without increase Ha-young Hyun

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.347-357
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• 1997

An accurate working length is an essential factor in the success of endodontic treatment. There are several methods for determining working length; electronic apex locator, tactile sense by clinician, and radiography. Among these methods, the most commonly used method is radiography. But this method requires excessive radiation, long developing time, and many equipments. In additon, it could give an image distortion and two dimensional image. To improve these disadvantages, an intraoral digital radiographic system (Digora$^{(R)}$) which use an imaging plate instead of a film, was developed. The purpose of this investigation was to compare Digora imaging with conventional radiography in determining the working length. Maxillary first or second molars of human dried skull were used. Files were inserted into canals at randomly selected lengths, from 2mm short of the radiographic apex to 2rnm beyond. Radiographs and Digora images(Digora positive and Digora negative) were evaluated to determine the adjustment needed to place the file 0.5mm from the radiographic apex. The results were as follows ; 1. There was no significant difference in accuracy between those evaluated in ${\pm}0.5mm$ and those accurately evaluated in the 3 images. 2. When comparing the accuracy of each image without distinguishing the 3 images, in the group accurately determined within ${\pm}0.5mm$, the mesiobuccal group showed significantly higher accuracy compared to the palatal group(p<0.05).

• The korean journal of orthodontics
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• v.18 no.2
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• pp.421-433
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• 1988

The purpose of this study was to investigate the characteristics of craniofacial morphology in adult with crowded dentition. The craniofacial morphology associated with normal and crowded of mandibular dentition was studied in lateral cephalometric radiograph obtained from 145 subjects grouped 44 males and 40 females in normal group, 33 males and 28 females in crowded group. The conclusions were as follows: Means, standard deviations and facial polygons from measurements were obtained from normal and crowded groups. Palatal plane to SN, occlusal plans to SN, mandibular plane to SN, mandibular plane to palatal plane and gonial angle measurements of crowded group were significantly different from normal group and were larger than normal group. SNA, SNB measurements of crowded group were significantly different from normal group and were smaller than normal group. Significant differences were observed between normal group and crowded groups on the basis of $SN/{\underline{1}}$, PP/1, $MP/{\bar{1}}$, and compared with normal group, upper incisors of crowded group were inclined more labially, whereas lower incisors of crowded group were inclined more lingually. Posterior facial height and ramal height were shorter in males of crowded group than those of normal group. Posterior facial height, mandibular length and posterior cranial base length were shorter in females of crowded group than those of normal group. Anterior facial height was longer in females of crowded group than those of normal group.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.25-35
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• 2020

The purpose of this study is to evaluate the morphological characteristics of the roots and roots canals of primary molar teeth using Cone-Beam Computed Tomography (CBCT). A total of 68 CBCT images of children aged 4 - 5 years was used for this study. A total of 160 molar teeth were analyzed. Various parameters such as the number of roots and canals, length of root and root canal, and the angulation and shape of the roots were analyzed. All maxillary primary molars had 3 roots. The presence of 2 root canals in 1 root was only observed in the mesiobuccal root of maxillary primary second molars. Most mandibular primary molars had 2 roots, and most mesial roots had 2 root canals. Concerning the length of the roots, the palatal root of the maxillary primary molar was found to be longest whereas the distobuccal root was shortest. In mandibular primary molars, the mesial root was longer than the distal root. In maxillary primary molars, the palatal root had the greatest angulation whereas the distal root has the greatest in mandibular molars. The root and root canals of maxillary primary molars were more curved in shape whereas mandibular primary molars were straight.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.3
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• pp.238-246
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• 2007

This study is aimed to elucidate the abnormal growth pattern of human fetal maxilla with cleft lip and palate (CLP). Total 71 fetal maxillae with CLP were obtained from aborted human fetuses. They were examined radiologically for the dimensional changes of maxillary trapezoid (MT) formed by maxillary primary growth centers (MxPGC)(Lee et al., 1992). In palatal radiogram of the CLP maxilla, the MT was traced by the anterior and posterior MxPGCs, and the dimensions of anterior and posterior maxillary widths, maxillary length, and MT length (MTL), and MT area were measured for evaluation of the basic growth pattern of the developing maxilla. The growth of anterior and posterior MxPGCs was severely retarded in the prenatal maxillae with CLPs, showing abnormal shape of MT. Cleft lip subjects without cleft palate also showed arrested growth of MT. Unilateral cleft lipalveolar cleft or cleft palate (UCL-AC/CP) and bilateral cleft lip-alveolar cleft or cleft palate (BCL-AC/CP) showed enhanced abnormal MT pattern. The abnormality of MT was most marked in BCL-AC/CP. It was also observed that the craniofacial malformations other than CLPs produced abnormal MT. In conclusion, the MT growth of prenatal CLP maxilla was severely arrested and resulting in abnormal MT shape on the palatal radiogram. BCL-AC/CP showed more protruded nasal septum than other types of CLPs, while UCL-AC/CP showed severe deviation of the protruded nasal septum towards the non-cleft side. Cleft lip only subjects also showed the abnormal growth of MT. These data suggest that the MT is primarily involved in CLPs, and MT shape could be utilized as a sensitive indicator for the analysis of maxillary malformation in different types of CLPs.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.25-38
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• 2001

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.459-466
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• 2010

Alveolar distraction osteogenesis (ADO) has been regarded as an acceptable treatment for the alveolar bone deficiency. For ADO at anterior maxillary area, the vector should be oriented to forward and down-ward direction to get an adequate occlusion with mandibular teeth and to increase bone length and width for implant placement. However, the conventional commercial distraction devices for ADO are designed to allow mainly downward movement of alveolar segment, even though a forward movement can be obtained a little by controlling of inclination of device. To make ADO with controllable bidirectional vector possible, we used customized devices using self-manufactured ABDUL (Alveolar Bone Distractor Using Lag screw principle) and commercial orthodontic palatal expansion device ($Hyrex^{(R)}$). In all cases (n = 4), ADO could be performed successfully and dental implants were able to placed with adequate occlusion. We report the procedures, advantages and disadvantages of these methods.

• The Journal of the Korean dental association
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• v.51 no.6
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• pp.330-336
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• 2013

Considering the high prevalence, transverse control in adult patients presenting relatively narrow maxillary width is a challenging issue. This study compared the pattern of arch expansion induced by either miniscrew-assisted rapid palatal expander (MARPE) or continuous archwire engaged on self-ligating brackets. Age-matched adults groups(N=15 each) were treated with respective appliance. In both groups, all intercanine, interpremolar, and intermolar widths increased, and significantly greater change was noted in the intermolar region. Buccal tipping was minimal in both groups. Subsequent arch length increase, lingual tipping of incisors and distal tipping of molars were also found in both groups. According to the results, it can be concluded that the MARPE induced generally more arch expansion, particularly in the intermolar width, indicating that the adults showing buccal crossbite of the molars may have to undergo expansion via MARPE prior to arch alignment using continuous archwire.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.115-125
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• 1984

A comparative study was undertaken to investigate the collapse of maxillary dental arch and palate in unilateral cleft lip and palate individuals. The material for this study consisted of 39 subjects with repaired unilateral cleft lip and palate (30 males, 9 females). The measurements of unilateral cleft lip and palate individuals were compared with the measurements of normal individuals (30 males, 30 females). All the subjects were in the mixed dentition stage and the mean age was almost the same. The following conclusions were obtained. 1. A large number of the maxillary dental arch of the unilateral cleft lip and palate individuals showed ${\Omega}$-shape, and the arch length was shorter than that of normal individuals. The intermolar width did not show significant difference between cleft group and group, but the intercanine width was mcuh smaller than that of normal individuals. 2. The palate of the unilateral cleft lip and palate subjects showed shorter and shallower form than that of normal subjects. 3. The palatal area of the unilateral cleft lip and palate subjects was smaller than that of normal subjects, and the cleft side area was much smaller than the opposing side area. 4. There was no significant sexual difference in measurements of maxillary dental arch and palate of the unilateral cleft lip and palate subjects.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.317-323
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• 2003

When making crown and bridges on anterior regions, many practitioners consider the esthetics the most. For this reason functional aspect are not considered as much as the esthetics. If the occlusion on the anterior region are not formed correctly, movement of the temporomandibular joint can be disturbed and excessive stress can be occur that pathologic condition can be under lied. On this case presentation will show the importance of the anterior guidance and suggest the appropriate protocol of using customized anterior guide table. A 45years old male had to remake both of the upper central and lateral PFM because of the porcelain fracture. The new PFM crowns were made conventional methods without considering the anterior guidance. After the temporary setting, the patient complained of discomfort and short looking upper anteriors. To solve these problems we had to restore the palatal contour and length of the new crowns by making customized anterior guide table using temporary crowns that contains patient's old anterior guidance. This procedure which is copying the pt's comfortable anterior guidance to the final prosthesis made them to be esthetic and patients to feel comfortable.