• Imaging Science in Dentistry
• /
• v.53 no.1
• /
• pp.61-67
• /
• 2023

Purpose: The aim of this study was to objectively detect simulated tooth ankylosis using a novel method involving cone-beam computed tomography (CBCT). Materials and Methods: Tooth ankylosis was simulated in single-rooted human permanent teeth, and CBCT scans were acquired at different current levels (5, 6.3, and 8 mA) and voxel sizes (0.08, 0.125, and 0.2). In axial reconstructions, a line of interest was perpendicularly placed over the periodontal ligament space of 21 ankylosed and 21 non-ankylosed regions, and the CBCT grey values of all voxels along the line of interest were plotted against their corresponding X-coordinates through a line graph to generate a profile. The image contrast was increased by 30% and 60% and the profile assessment was repeated. The internal area of the resulting parabolas was obtained from all images and compared between ankylosed and non-ankylosed regions under different contrast enhancement conditions, voxel sizes, and mA levels using multi-way analysis of variance with the Tukey post hoc test(α=0.05). Results: The internal area of the parabolas of all non-ankylosed regions was significantly higher than that of the ankylosed regions(P<0.05). Contrast enhancement led to a significantly greater internal area of the parabolas of non-ankylosed regions (P<0.05). Overall, voxel size and mA did not significantly influence the internal area of the parabolas(P>0.05). Conclusion: The proposed novel method revealed a relevant degree of applicability in the detection of simulated tooth ankylosis; increased image contrast led to greater detectability.

• The korean journal of orthodontics
• /
• v.18 no.1 s.25
• /
• pp.217-225
• /
• 1988

This study was undertaken to examine relationship between tooth size and arch dimension in dental crowding. Two groups of dental casts were selected on the basis of dental crowding. One group, consisting of 51 pairs of dental casts (24 male and 27 female), exhibited remarkable dental crowding. A second group, consisting of 60 pairs of dental casts (30 male and 30 female), exhibited little or no crowding. Mean and standard deviation of the following parameters were used to compare two groups. individual and collective mesiodistal tooth diameters, buccal and lingual arch widths and arch area. The following results were obtained. 1. The crowed group revealed larger tooth size than noncrowded group. (p < 0.01) 2. The crowded group smaller maxillary dental arch dimension than noncrowded group except lingual arch width at canine region. (p < 0.01) 3. The corwded group revealed smaller mandibular dental arch dimension than noncrowded group except lingal arch width at second premalar region in the male and buccal arch width at canine, premolar region in the female. (p < 0.01) 4. The crowded group revealed smaller arch area than noncrowded group in the female (p < 0.01), but there was no significance in the male.

• The Journal of Advanced Prosthodontics
• /
• v.2 no.4
• /
• pp.122-127
• /
• 2010

PURPOSE. The aim of this study was to examine the relationship between tooth loss and sub-clinical atherosclerosis in Korean adults. MATERIALS AND METHODS. The subjects were part of a cohort study conducted in Ansan city by the Korea University medical school as part of the Korean Genome project. 749 subjects over than 40 years old were evaluated. After taking panoramic radiography, the amount of tooth loss was calculated. The intima-media thickness (IMT) was assessed by using ultrasonography at the common carotid artery. Traditional cardiovascular risk factors for atherosclerosis were also evaluated. The relationship between tooth loss and the IMT was evaluated using ANOVA with Scheffe's multiple comparison method in univariate analysis. Multiple regression analysis was also performed to determine the significance between the IMT and tooth loss. RESULTS. With age, tooth loss increased, but there was no significant increase in other traditional cardiovascular risk factors. Univariate analysis revealed the IMT to be positively related with the amount of tooth loss. Regression analysis of the IMT in the anterior and posterior tooth loss revealed that only the posterior tooth loss was significantly related with the IMT at all sites of the common carotid artery (right far wall, P = .015; left far wall, P = .008; right near wall, P < .001; left near wall, P = .001). CONCLUSION. This study verified the positive relationship between the increased tooth loss at the posterior area and the accumulation of atheroma in arteries.

• Journal of Periodontal and Implant Science
• /
• v.33 no.3
• /
• pp.383-393
• /
• 2003

The aim of this retrospective study was to compare the amount of marginal bone loss between upper anterior area and upper posterior area with 71 upper single-tooth restorations on 2 stage machined $Br{{\aa}}nemark$ implants since Jan 1995. The second aim was to compare the bone defect group which had dehiscence and fenetration and the others in the upper anterior region. The results were as follows. 1. The most frequent reason of missing tooth in the upper anterior region was trauma by 61%. While upper posterior region showed various reasons such as congenital missing, advanced periodontitis, trauma. 2. Peri-implantitis with fistula occurred 1 of 41 implants in the upper anterior group in 1 year after loading and 2 of 32 implants in the upper posterior group failed before loading. The 1 year success rate of upper anterior group was 97.56 %, and 93.75 % for upper posterior group. 3. The mean marginal bone loss in the upper anterior group was 0.44${\pm}$0.25 mm, while 0.57${\pm}$0.32 mm in the upper posterior group. There was statistically significant difference in the amount of mean marginal bone loss (P${\pm}$0.10 mm at one year, and 0.48${\pm}$0.26 mm for the control group. No statistically significant difference of mean marginal bone loss was showen between bone defect group and the others at implantation. According to the results, the upper anterior region showed less marginal bone loss than the upper posterior region. In case of missing single upper tooth, careful consideration on recipient residual ridge to determine proper implant diameter and length, sufficient healing time, proper loading would lead to implant success. Single tooth implants in the maxilla seemed to be an alternative to fixed partial dentures without damage to adjacent teeth.

• Journal of Oral Medicine and Pain
• /
• v.23 no.2
• /
• pp.193-209
• /
• 1998

In identifying bodies that are severely decayed or damaged, methods using fingerprints and various biochemical tests are known to have its limits. To overcome this, forensic odontological method which is based on the analysis of the cranium, tooth and dental restoration is used to enhance the accuracey of individual identification. For this reason, I have come to analysis of the dental materials that exists between the teeth that is perceived to have been previously restored and the one adjacent to it. By analyzing the constituents of gold crown-restored, non-precious metal-restored, gold inlay-restored and amalgam -restored teeth, and adjacent teeth using EDX(energy dispersive X-ray microanalysis) which was invented to analyze very small amount of elements, the nature of the restoration could be predicted and the results obtained were as follows. 1. Some of constitute of gold alloy was extracted from residual cement of gold crown restoration, but that was not extracted from the restored tooth and the one adjacent to it. 2. Some of constituents of non-precious metal alloy was extracted both in the residual cement on the tooth with no-precious metal restoration and in the tooth with the restoration itself. However, none of its constituents were found in the tooth adjacent to it. 3. Some of constituents of gold alloy were found in the residual cement of gold inlay, but they were not found in the restored tooth and the adjacent tooth. 4. Some of constituents of amalgam alloy were found both in tooth restored with amalgam and in the adjacent tooth. From the results obtained above, it is possible to utilize the data obtained from analyizing residual dental materials in a more effective way. This data compensates for the lost data due to any harm done to the restorations prior to individual identification and further enhances the accuracy. Therefore, it could be concluded that this process of analyzing residual dental materials could be beneficial to individual identification in the area of forensic odontoldogy.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.4
• /
• pp.718-724
• /
• 2008

Tooth impaction is a frequently observed eruption anomaly in pediatric dental practice. Young patients with impacted or unerupted teeth have more prediction for dentigerous cyst formation. Dentigerous cyst presents radiographic features, unilocular or multilocular radioluscency. Cysts occur most frequently in the premolar region except third molar. Dentigerous cysts can grow to a considerable size, and large cysts may be associated with a painless expansion of the bone in the involved area. Extensive lesions may result in facial asymmetry, osseous destruction, root resorption of proximal teeth and displacement of associated tooth. The nature of the causative tooth influences the type of surgical treatment required for the dentigerous cyst. If the cyst is associated with a supernumerary or wisdom tooth, complete enucleation of the cyst along with extraction of tooth may be the first treatment choice. Otherwise, preservation of the associated teeth should be considered to prevent a young patient from psychological and mental trauma because of the loss of tooth. We should consider the degree of tooth displacement, osseous destruction and growth pattern of oromaxillofacial area when planning treatment. Thus a proper and logical treatment planning can help a proper growth and development of oromaxillofacial area and can save the patient from a psychological and mental trauma. This report describes 4 cases of the management of impacted premolars and molars associated with dentigerous cysts in children.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.30 no.6
• /
• pp.551-553
• /
• 2004

The displacement of an entire tooth into the adjacent anatomical area is an uncommon complication of a tooth extraction. We encountered a 23-year-old woman who had previously undergone surgery under local anesthesia to remove the lower third molar about 12 weeks prior and the upper third molar was extracted 2 days prior to visiting this hospital. Upon admission, she complained of a swallowing discomfort and a mouth opening limitation. Panoramic radiograph and a CT scan revealed a displacement of the entire tooth into the lateral pharyngeal space. The tooth was retrieved via the transoral approach under general anesthesia. The removed tooth had an indentation formed by a dental bur. Therefore, it was concluded that the tooth displaced into the lateral pharyngeal space was the lower third molar. This report describes an unusual case of a third molar that was displaced into the lateral pharyngeal space with a review of the relevant literature.

• Imaging Science in Dentistry
• /
• v.47 no.2
• /
• pp.117-122
• /
• 2017

Purpose: The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement. Materials and Methods: Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient(ICC) was used to assess intraobserver reliability. Results: The root surface area measurements ($230.11{\pm}41.97mm^2$) obtained using CBCT were slightly greater than those ($229.31{\pm}42.46mm^2$) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT. Conclusion: This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.857-860
• /
• 1996

The area of gear dynamics has recently been the focus of many studies. A new tooth profile modification was proposed by author for reducing vibration and noise of involute gears. A comparative dynamic analysis of the gear drive with the involute tooth and the modified tooth profile(using cubic splines) is performed to the unuformal transmission error reduces the gear vibration and noise due to less dynamic tooth load variation during the meshing cycle. This work also include a gear design process by the meaning of a practical approach, such as Win95 based simulation program with all using basic geardesign variables. Especially this program enables gear designers to dynamic analysis based on G.U.I.

• The Journal of Korea Assosiation for Disability and Oral Health
• /
• v.10 no.2
• /
• pp.84-88
• /
• 2014

Traditional method of pulpectomy for a necrotic primary anterior tooth was done on lingual side. But it could not recover the discoloration of crown effectively. For the purpose of treating the discoloration of crown after lingual pulpectomy, additional methods of crown restoration were needed like : celluloid crown, open-faced crown, rasin-faced crown. Neverthless, these kinds of complete coverage methods had some disadvantages such as possibility of tooth fracture by increased tooth preparation. In order to overcome the shortcomings of lingual pulpectomy, labial treatment could be considered as an alternative. It is a method that treats necrotic pulp through the labial access opening. After finishing the pulp treatment, discolored labial tooth structure was removed extending from access opening. Discoloration of deep area could be masked effectively using opaque sealant. Cavity on labial side was restored with composite resin. This labial approach method has several advantages. First, it gives a direct vision for effective pulp treatment which is also very useful for children with poor behavior. Second, most of lingual tooth structure could be saved and occlusal contact of lingual surface remains undisrupted. Only nonfunctional discolored labial surface may removed. Third, complete removal of discolored part of a labial tooth and immediate resin restoration could be done effectively after pulp treatment. Moreover, it also could be used for pulp treatment having serious dental caries on labial surface with sound lingual tooth structure. This report presents cases with discolored upper anteior primary tooth, approaching labial side with successful restoration.