• Imaging Science in Dentistry
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• v.43 no.3
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• pp.191-196
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• 2013

Purpose: This study assessed the accuracy of linear and angular measurements on panoramic radiographs taken at different positions in vitro. Materials and Methods: Two acrylic models were fabricated from a cast with normal occlusion. Straight and $75^{\circ}$ mesially and lingually angulated pins were placed, and standardized panoramic radiographs were taken at standard position, at an $8^{\circ}$ downward tilt of the occlusal plane compared to the standard position, at an $8^{\circ}$ upward tilt of the anterior occlusal plane, and at a $10^{\circ}$ downward tilt of the right and left sides of the model. On the radiographs, the length of the pins above (crown) and below (root) the occlusal plane, total pin length, crown-to-root ratio, and angulation of pins relative to the occlusal plane were calculated. The data were subjected to repeated measures ANOVA and LSD multiple comparisons tests. Results: Significant differences were noted between the radiographic measurements and true values in different positions on both models with linear (P<0.001) and those with angulated pins (P<0.005). No statistically significant differences were observed between the angular measurements and baselines of the natural head posture at different positions for the linear and angulated pins. Conclusion: Angular measurements on panoramic radiographs were sufficiently accurate and changes in the position of the occlusal plane equal to or less than $10^{\circ}$ had no significant effect on them. Some variations could exist in the pin positioning (head positioning), and they were tolerable while taking panoramic radiographs. Linear measurements showed the least errors in the standard position and $8^{\circ}$ upward tilt of the anterior part of the occlusal plane compared to other positions.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.70-86
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• 1996

The purpose of this study was to analyze the stress distribution in mandibular second premolars restored with different post and core techniques. Sixteen two-dimensional finite element model of mandibular second premolars restored with post and core and complete crown were developed according to the diameter, length, and material of post and core. Vertical force, 10N in magnitude, was applied first to the central fossa and then $45^{\circ}$ oblique force of same magnitude was applied to the buccal contact surface of buccal cusp. The obtained results were as follows : 1. Stress distribution within the dentin 1) Regardless of the material of the post and core and the diameter and length of the post, the pattern of stress distribution within the dentin was similar. 2) Maximum dentinal stress was observed on the lingual root surface of alveolar crest level with oblique loading and on lingual side of root dentin at the crown margin on vertical loading. 3) Cast post and cores produced the lowest dentinal stress concentrations and the highest stress concentration was observed in composite resin post and cores. 2. Stress distribution within the post and core 1) Within the amalgam and composite resin post and core, the patterns and maximum values of stress were similar. Maximum stress located at the central fossa of core portion on vertical loading and at the lingual junction of post and core with oblique loading. 2) Among the all post and cores, the cast post and core registered the highest stress concentration and maximum stress value within the post. Maximum stress located at the post apex on vertical loading and at lingual half of the post surface with oblique loading. 3) In case of Para-post and amalgam core, maximum stress located at the central fossa of core portion and lingual tip of the post head on vertical loading. With oblique loading, maximum stress located at the lingual half of the post surface.

• The Research Journal of the Costume Culture
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• v.22 no.5
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• pp.670-687
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• 2014

This study focused on Jungchimak (coats with side slits) which was typically worn by men in the mid and late Joseon Dynasty. It was done research by examining the case of wearing Jungchimak centering on literature and paintings and analyzing its changes in terms of its form based on the relics that have been found in order to suggest the standard for the evaluation of the period of Jungchimak. Results are as follows. First, men who wore Jungchimak were the king, crown prince and Aristocratic under the official uniform or other robes or as ordinary clothes and shroud. Second, Jungchimak for king was mostly made of Dan (satin damask) and mostly jade green & navy in color, and it commonly used dragon pattern, cloud and treasure pattern, or grape pattern. The fabric used to make Jungchimak for crown prince was Dan & Ju (coarse-finished silk) and puple, green, jade green & navy in color. The fabric used to make Jungchimak for Aristocratic was Ju and indigo or white in color. Third, 251 relics have been announced until now. Most of them were made of silk fabric and had cloud and flower patterns. Fourth, Jungchimak showed changes through time in terms of collar and sleeve shapes, the ratio of armhole to sleeve opening, Geotseop (panel sewn on front opening for overlapping), Dang and Mu (side panel), the ratio of the total length of outer collar to the length of side slits, and the ratio of chest size to the width of lower end.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.293-302
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• 2007

I. Objectives The purpose of this study was to compare the shaping ability between the single length technique performed with Mtwo instruments (VDW, Munich, Germany) and the crown-down technique using K3 (SybronEndo, West Collins, CA, USA) and RaCe (FKG, La Chaux-de-Fonds, Switzerland) instruments. II. Materials & Methods Forty five curved canals in resin blocks were equally divided in to three groups. Group 1 (Mtwo) was instrumented used the full length of canal according to the manufacturer's instructions. The simulated canals was prepared to an instrument size of 35, 0.04 taper canal terminus. In group 2 (Race) and group 3 (K3) was instrumented in a crown-down manner and prepared to an instrument size of 30, 0.06 taper canal terminus. Pre- and post-instrumentation images were scanned and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 7 measuring points, beginning 1mm from the end point of preparation. Differenced of centering ratio were statistically analyzed using One-way ANOVA followed by Duncan's test. II. Results & Conclusion There was no significant difference on 1, 2, 3 and 7mm measuring point. At 4 and 5 measuring point, significant difference showed between the Mtow instruments and other two instruments. (p<0.05)

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.147-154
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• 2012

Purpose: This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods: The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results: The periapical radiographs of 564 teeth showed that the average root resorption was $1.39{\pm}1.27$ ($8.24{\pm}7.22$%) and $1.69{\pm}1.14$ mm ($10.16{\pm}6.78%$) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion: These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.1
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• pp.85-97
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• 1995

The arrangement of anterior artificial teeth is an important factor on the esthetics in the construction of complete denture and prosthesis. During construction of the complete denture the position of maxillary central incisor plays an important role in the arrangements of artificial teeth. The proper position of maxillary central incisor provides natural appearance of anterior teeth and the anterior reference point of occlusal plane. Many methods have been utilized to eatablish the position of the maxillary central incisor in complete denture prosthodontics. However, there has not been provided for the reference for Korean yet. This study was aimed to extablish the position of the maxillary central inciosr in Korean. The horizontal and vertical distance between the maxillary central incisor and incisive papilla in korean were measured. The results were as follows : 1. The mean value of horizontal distance from the maxillary central incisor to the incisive papilla had significant sexual difference, the average distance was 12.648mm (male), 11.385mm(female). 2. The horizontal distance of incisive papilla had sexual difference, the average distance was 6.182mm(male), 5.622mm(female). 3. The vertical distance from the maxillary central incisor to the incisive papilla had not sexual difference, the average distance was 7.21mm. 4. The crown length of maxillary central inciosrs from the distal interdental papilla had not sexual difference, the right central incisor was 6.40mm(mean) and the left central inciosr was 6.43mm(mean). 5. The clinical crown length of the maxillary central incisors had not sexual difference, the right central incisor 10.35mm(mean) and the left central incisor was 10.43mm(mean). 6. The anatomic shapes of incisive papilla were pear(68.4%), oval(16%), triangular(6%), irregular(5%), rectangular(4%), and inverted pear(1%) shape.

• Journal of Periodontal and Implant Science
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• v.38 no.3
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• pp.475-482
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• 2008

Purpose: To evaluate the safety and efficiency of bone regenerative abilities of silk fibroin nanomembrane(Nanoguide-S) Material and Methods: The objects were 38 patients who had large defect at extraction sockets caused by chronic periodontitis and silk fibroin nano matrix were used on experimental group(N=19) and PLA/PLGA matrix were used on control group(N=19). The width, height, and length by crown-apical direction(socket depth) of defects were measured with the occlusal plane as a reference plane, and tooth axis direction, perpendicular to tooth axis direction were measured on radiographs at 3 months pre-operative, 3 months post-operative. Result: Tissue response to silk fibroin nano matrix and Biomesh were clinically satisfactory and complications such as swelling, exudation, ulceration and vesicles were not found except the ordinary discomfort of operated portion. 3 months later, the width, height, and length by crown-apical direction (socket depth) of defects were clinically improved in both groups with no significant difference. 3 months later radiolucency of tooth axis direction and perpendicular to tooth axis direction were all increased in both groups with no significant difference. Conclusion: By these results biodegradadable silk fibroin nano matrix was efficient in GBR on alveolar bone resorption caused by periodontitis compared to Biomesh.

• Anatomy and Cell Biology
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• v.57 no.2
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• pp.288-293
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• 2024

The temporal fascia is a double lamina sandwiching a thick fat layer above the zygomatic bony arch. To characterize each lamina, their developmental processes were examined in fetuses. We observed histological sections from 22 half-heads of 10 mid-term fetuses at 14-18 weeks (crown-rump length, 95-150 mm) and 12 near-term fetuses at 26-40 weeks (crown-rump length, 215-334 mm). The superficial lamina of the temporal fascia was not evident at mid-term. Instead, a loose subcutaneous tissue was attached to the thin, deep lamina of the temporal fascia covering the temporalis muscle. At near-term, the deep lamina became thick, while the superficial lamina appeared and exhibited several variations: i) a mono-layered thick membrane (5 specimens); ii) a multi-layered membranous structure (6) and; iii) a cluster of independent thick fasciae each of which were separated by fatty tissues (1). In the second and third patterns, fatty tissue between the two laminae was likely to contain longitudinal fibrous bands in parallel with the deep lamina. Varying proportions of the multi-layered superficial lamina were not attached to the zygomatic arch, but extended below the bony arch. Whether or not lobulation or septation of fatty tissues was evident was not dependent on age. The deep lamina seemed to develop from the temporalis muscle depending on the muscle contraction. In contrast, the superficial lamina developed from subcutaneous collagenous bundles continuous to the cheek. Therein, a difference in development was clearly seen between two categories of the fasciae.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.761-776
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• 2005

The purpose of the present study was to examine the relationship between the form of the clinical crowns in the maxillary anterior segment and the clinical feature of gingiva such as morphological characteristics and the gingival thickness. Fifty periodontally healthy subjects were clinically examined regarding the probing depth, the thickness of the free gingiva, and the width of the keratinized gingiva. From study models of the maxillary anterior region, the width at cervical third(CW) and the length(CL) of the clinical crown, the papillary height, and the gingival angle of the 6 anterior teeth were measured. Each tooth was classified into 4 groups (longnarrow, NL; narrow, N; wide, W; short-wide, WS) according to CW/CL ratio and all the data were compared between groups NL and WS using independent t-test. Stepwise multiple regression analysis was performed for each tooth region with the gingival thickness at the level of sulcus bottom, the width of keratinized gingiva, and gingival angle as the dependent variables. As the results, the NL group of the upper anterior teeth displayed, higher papilla height, and narrower keratinized gingiva, more acute gingival angle resulting in pronounced "scalloped" contour of the gingival margin, compared to the WS group. There was no significant difference between groups NL and WS with respect to probing depth and the gingival thickness. The regression analyses demonstrated that the gingival thickness in central incisors was significantly associated to the mesio-distal width and bucco-lingual width of the crown, and labial probing depth. The width of keratinized gingiva was significantly associated with labial probing depth in central incisors and with proximal probing depth and gingival angle in lateral incisors, and with labial and proximal probing depth, and gingival angle in canines. The gingival angle was significantly associated with papillary height and CW/CL ratio and additionally with proximal probing depth in central incisors, with the width of keratinized gingiva in lateral incisors, and with labial probing depth and the width of keratinized gingiva in canines. These results indicate that the form of clinical crown in upper anterior region could influence the clinical feature of gingiva and the influencing factors might be different according to the tooth region.

• The korean journal of orthodontics
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• v.47 no.6
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• pp.365-374
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• 2017

Objective: The objective of this study is to investigate the eruption pattern and root resorption of the bovine anterior dentition in relation to growth-related parameters based on dental maturity. Methods: A cross-sectional study was conducted on 110 bovine anterior mandibles by using standard radiography, cone-beam computed tomography (CBCT), and actual measurements. We determined the relationships between the stages of dental maturity by using a modification of Demirjian's method and various growth-related parameters, such as the activity of the root-resorbing tissue and mobility of the deciduous teeth. The correlation of growth-related parameters with interdental spacing and distal unusual root resorption (DRR) of the deciduous fourth incisor was assessed. The cause of mesial unusual root resorption (MRR) of the deciduous fourth incisor was determined on the basis of the arrangement of the permanent third incisor. Results: An independent t-test and chi-square test indicated significant differences in growth-related parameters associated with dental arch length discrepancy and factors related to the shedding of deciduous teeth between the low and high dental maturity groups. The samples with interdental spacing and DRR showed a larger sum of mesiodistal permanent crown widths and higher dental maturity than did the respective controls. Samples with MRR tended to show a lingually rotated distal tip of the adjacent tooth crown. Conclusions: Dental maturity has relevance to the interdental spaces and unusual root resorption of mixed dentition. The position of the adjacent tooth crown on CBCT may be correlated with the occurrence of unusual root resorption of the incisor.