• Journal of dental hygiene science
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• v.13 no.2
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• pp.203-212
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• 2013

The tooth morphology and qualitative mineral contents on enamel surface using energy dispersive X-ray spectroscopy, (EDX) were examined in the white-toothed shrew (genus Crocidura ) Crocidura lasiura and C. suaveolens and the red-toothed shrew (genus Sorex) Sorex caecutiens. In the case of C. lasiura and C. suaveolens, dental formula was found I 3/1 C1/1 P1/1 M3/3=28. The upper 1st and 2nd molars had an unequal W-shape formed by 5 cusps on the crown. The 3rd molar was found one-third the size of those of 1st and 2nd molars. The upper 1st incisor had two different sized hook-shapes and the lower 1st incisor was even. In the case of S. caecutiens, dental formula was found to be I3/1 C1/1 P3/1 M3/3=32. The upper 1st and 2nd molars had an equal W-shape on crown. The upper 3rd molar was half the size of those of the other molars. The upper 1st incisor possessed two similar sized hook-shapes and the lower 1st incisor had an uneven and serrated form. A comparison with the dental and cranial measurements revealed C. lasiura to be the largest of the three species (p<0.001) and C. suaveolens and S. caecutiens were similar in size (p>0.05). A qualitative analysis of mineral contents on enamel surface of the lower 1st incisor and lower 1st molar using EDX revealed C, O, P, Ca and Cu in all specimens and Pb was detected in several enamel specimens. No significant differences in the mineral contents (% weight) were observed among the three species (p>0.05). Fe was only detected on enamel surface of S. caecutiens with red pigmented teeth. Therefore, Fe is responsible for the red tip of the teeth. These results suggest that tooth morphological characteristics including the color of the tooth tip might be used as the key classifying species belonging to Crocidura and Sorex.

• The korean journal of orthodontics
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• v.42 no.1
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• pp.47-54
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• 2012

Objective: To determine and compare the frequency distribution of various arch shapes in ethnic Malays and Malaysian Aborigines in Peninsular Malaysia and to investigate the morphological differences of arch form between these two ethnic groups. Methods: We examined 120 ethnic Malay study models (60 maxillary, 60 mandibular) and 129 Malaysian Aboriginal study models (66 maxillary, 63 mandibular). We marked 18 buccal tips and incisor line angles on each model, and digitized them using 2-dimensional coordinate system. Dental arches were classified as square, ovoid, or tapered by printing the scanned images and superimposing Orthoform arch templates on them. Results: The most common maxillary arch shape in both ethnic groups was ovoid, as was the most common mandibular arch shape among ethnic Malay females. The rarest arch shape was square. Chi-square tests, indicated that only the distribution of the mandibular arch shape was significantly different between groups (p = 0.040). However, when compared using independent t-tests, there was no difference in the mean value of arch width between groups. Arch shape distribution was not different between genders of either ethnic group, except for the mandibular arch of ethnic Malays. Conclusions: Ethnic Malays and Malaysian Aborigines have similar dental arch dimensions and shapes.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.91-98
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• 2006

Supernumerary teeth are teeth which result from the continued budding of the enamel organ of the preceding tooth or from excessive proliferation of cells. They are most often found in the maxillary anterior region. And they can be responsible for a variey of irregularities in the primary and transitional dentition. There are two morphological types of supernumerary teeth, supplemental and rudimentary. Supplemental teeth have normal shape and size. In contrast, rudimental teeth have abnormal shape and smaller size. Supplemental supernumerary teeth are most common in permanent lateral incisor area. Its extraction must be decided more carefully with differential diagnosis between normal teeth, because it has normal shape and size. We reports 3 cases of the normal incisor shaped teeth in the maxillary anterior region. In all cases, we used the 3D Dental-CT as well as the conventional plain film such as periapical, occlusal, and panoramic radiograph. Consequently, 3B Dental-CT was valualble to figure out the exact position and morphology of supernumerary teeth, to do more conservative surgery and to reduce surgery stress and time.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.367-375
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• 1991

The clinical and radiographic features of 1,171 mesiodenses were studied with periapical radiograms and/or pantomograms in 942 persons visited the Department of Oral Radiology, School of Dentistry, Kyung Hee University during January 1980 to December 1989. The obrained results were as follows; 1. The incidence of mesiodens was higher in males (75.4%) than in females (24.6%). 2. In number of mesiodenses per individual, a single mesiodens was found to be 75.9%, 2-mesiodenses to be 23.8%, and 3-mesiodenses to be 0.2%. 3. In mesiodenses according to erupted and impacted status, the erupted mesiodens was found to be 16.5%, the impacted mesiodens in the interdental alveolar bone to be 66.6%, and in the region below root apex to be 16.9%. 4. In impacted mesiodenses according to direction of tooth crown, the inverted impaction was found to be 68.8%, the vertical impaction to be 15.1%, and the angulated impaction to be 16.1%. Among the impacted mesiodenses, a palatally located impaction was 87.5%, a middle 4.9%, and a labially 7.6%. 5. In mesiodenses according to shape of the tooth crown, a incisor-like type was found to be 1.6%, a canine-like type to be 6.8%, a conical type to be 79.2%, and a tuberculated type to e 12.4%. 6. In effect of mesiodens on adjacent tooth, non-specific influences were found to be 73.4%, crowding to be 0.3%, diastema to be 11.8%, rotation to be 5.7%, delayed eruption to be 3.8%, root resorption to be 2.6%, and dentigerous cyst to be 2.4%.

• Imaging Science in Dentistry
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• v.34 no.1
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• pp.7-12
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• 2004

Purpose: To investigate the anatomical structure of the incisive canal radiographically by a cone beam computed tomography. Materials and Methods: 38 persons (male 26, female 12) were chosen to take images of maxillary anterior region in dental CT mode using a cone beam computed tomography. The tube voltage were 65, 67, and 70kVp, the tube current was 7 mA, and the exposure time was 13.3 seconds. The FH plane of each person was parallel to the floor. The images were analysed on the CRT display. Results: The mean length of incisive canal was 15.87 mm±2.92. The mean diameter at the side of palate and nasal fossa were 3.49 mm±0.76 and 3.89 mm± 1.06, respectively. In the cross-sectional shape of incisive canal, 50% were round, 34.2% were ovoid, and 15.8% were lobulated. 87% of incisive canal at the side of nasal fossa have one canal, 10.4% have two canals, and 2.6% have three canals, but these canals were merged into one canal in the middle portion of palate. The mean angles of the long axis of incisive canal and central incisor to the FH plane were 110.3°±6.96 and 117.45°±7.41, respectively. The angles of the long axis of incisive canal and central incisor to the FH plane were least correlated (r= 0.258). Conclusion : This experiment suggests that a cone beam computed radiography will be helpful in surgery or implantation on the maxillary incisive area.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.2
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• pp.166-173
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• 2012

Dilaceration is a developmental disturbance in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth. Dilacerations are estimated to occur in 3% of all permanent dentitions. However, the etiology of dilaceration is not yet fully understood. Traumatic injury to the deciduous predecessors and ectopic development of the tooth germ are the two commonly cited causes of this anomaly. The involved tooth is usually the maxillary central incisor and it also shows high prevalence of impaction. At first, We tried to do surgical exposure with orthodontic traction but to no avail. After then surgical repositioning of the dilacerated tooth was performed. Finally, Satisfactory results were obtained at the end of treatment, with improvement in dental esthetics and functional aspects.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.3
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• pp.170-179
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• 2019

The prosthodontic treatments in maxillary anterior teeth focus on achieving esthetic appearances. It is possible to improve the esthetic appearance by adjusting the shape, arrangement, and color of the maxillary anterior teeth. For anterior teeth restoration, it is necessary to evaluate the relationship of teeth, lip and gingival architecture with the facial profile of patient. Also, clinician needs to fully understand what the patient wants to. DSD (digital smile design) concept can be applied as a tool to improve communication with the clinician, technician and patient. In addition, DSD can help to meet the needs of the patient. In this case, it was impossible to achieve symmetry due to congenital missing of maxillary central incisor. The definitive treatment goal was to get the harmony of maxillary anterior teeth, lip and the patient's face. This case report describes that the patient and clinician got the satisfying esthetic outcome by using DSD.

• Journal of Technologic Dentistry
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• v.46 no.1
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• pp.1-7
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• 2024

Purpose: The goal of this study was to determine the clinical acceptability of various cement space settings for the marginal and internal fit of a zirconia core manufactured using additive manufacturing. Methods: The maxillary right incisor served as the master model. After scanning the maxillary right incisor with a dental 3D (three-dimensional) scanner, the stereo lithography file was created using different cement space settings of 40, 120, and 200 ㎛ using computer-aided design software (Dental System 2018; 3Shape). The marginal and internal fit of the 3 groups were determined using the silicon replica technique. Measurement points were divided into the following three categories: margin, axial wall, and incisal. To ensure more accurate measurements, these three measurement points were divided into 8 points. The Shapiro-Wilk, one-way ANOVA, and Tukey's honestly significant difference test (for all tests α=0.05) were the statistical analyses that were included in the study. Results: The CS (cement space)-200 group had better marginal and internal fit than the CS-40 and CS-120 groups, and there were statistically significant differences at the marginal and incisal points, except for the axial wall points. CS-200 group, both marginal and internal fit were within 120 ㎛, which is the clinically acceptable value. Conclusion: This study suggests that a 200 ㎛ cement space setting is ideal for optimal marginal and internal fit of 3D-printed ceramic crowns.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.91-98
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• 1987

This study was designed to investigate the changing depositional pattern of inorganic enamel substances during enamel formation and maturation. For this purpose, white rat incisors which continuously grow and develop during the life, were chosen as specimens. And after treated with 20% KOH solution, outer surface of forming inorganic enamel were observed with the scanning electron microscope, dividing into 6 types according to the forming pattern from apical to cuspal direction. The observations lead to the following conclusions: 1. During the initial enamel forming stage, inorganic enamel substances were deposited with very irregular pyramidal shape on the root dentin surface. 2. During the enamel forming stage, inorganic enamel substances were deposited with relatively regular hexagonal, honey-comb appearance. 3. During the later enamel forming stage, inorganic enamel substances were deposited with very irregular and roughly amorphous appearance. 4. During the later enamel maturating stage, very small and round inorganic enamel substances were deposited densely, and made a flat enamel surface.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1678-1684
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• 2018

Dental caries is one of the most popular oral disease. The aim of automatic dental cavity detection system is helping dentist to make accurate diagnosis. It is very important to separate cavity from the teeth in the detection system. In this paper, We compared two active contour algorithms, Snake and DRLSE(Distance Regularized Level Set Evolution). To improve performance, image is selected ROI(region of interest), then applied bilateral filter, Canny edge. In order to evaluate the algorithms, we applied to 7 tooth phantoms from incisor to molar. Each teeth contains two cavities of different shape. As a result, Snake is faster than DRLSE, but Snake has limitation to compute topology of objects. DRLSE is slower but those of performance is better.