• Imaging Science in Dentistry
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• v.45 no.3
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• pp.147-151
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• 2015

Purpose: The aim of this study was to investigate the effects of metal artifacts on the accurate diagnosis of root fractures using cone-beam computed tomography (CBCT) images with large and small/limited fields of view (FOVs). Materials and Methods: Forty extracted molar and premolar teeth were collected. Access canals were made in all teeth using a rotary system. In half of the teeth, fractures were created by the application of mild pressure with a hammer. The teeth were then randomly put into a wax rim on an acryl base designed in the shape of a mandible. CBCT scans were obtained using a Newtom 5G system with FOVs of $18cm{\times}16cm$ and $6cm{\times}6cm$. A metal pin was then placed into each tooth, and CBCT imaging was again performed using the same fields of view. All scans were evaluated by two oral and maxillofacial radiologists. The specificity, sensitivity, positive predictive value, negative predictive value, and likelihood ratios (positive and negative) were calculated. Result: The maximum levels of sensitivity and specificity (100% and 100%, respectively) were observed in small-volume CBCT scans of teeth without pins. The highest negative predictive value was found in the small-volume group without pins, whereas the positive predictive value was 100% in all groups except the large-volume group with pins. Conclusion: The specificity of CBCT decreased with the presence of a pin in the large-volume group, but not in the small-volume group.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.85-92
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• 2017

PURPOSE. The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS. Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. RESULTS. The highest bond strength values for all cements were achieved with etching and primer on enamel ($25.6{\pm}5.3-32.3{\pm}10.4MPa$). On dentin, etching and priming produced the highest bond strength values for all cements ($8.6{\pm}2.9-11.7{\pm}3.5MPa$) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only ($15.3{\pm}4.1MPa$). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. CONCLUSION. The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.225-233
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• 1998

The principle, design, and application of a gear-tooth sensor for the rough environmental conditions such as high temperatures of up to $150^{\circ}C$ are studied. The rotation of a tooth wheel is detected by a couple of Hall elements manufactured on the SIMOX wafer by a methode of differential detection using bipolar silicon technology. The product sensitivity of the Hall element is about 510 V/AT over a wide temperature range of $-40^{\circ}C{\sim}150^{\circ}C$. The differential Hall sensor makes the maximum possible distance between sensor and tooth wheel wider than that when single Hall element is used over a wide temperature range, and the maximum detectable distance is 4.5mm at driving current of 4mA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.91-98
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• 2008

Hypoid gears are widely used in rear drive and 4WD vehicle axles. Investigation of their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. The deflection test is performed in the actual gear mounting using completely processed gear. This test should cover the fun operating range of gear loads from no load to peak load. Under peak load the contact pattern should extend to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. Transmission error is tested on an axle assembly triaxial real car load condition.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1040-1047
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• 2008

Hypoid gears are widely used in rear drive and 4WD vehicle axles. Investigation of their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. The deflection test is performed in the actual gear mounting using completely processed gear. This test should cover the full operating range of gear loads from no load to peak load. Under peak load the contact pattern should extend to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. Transmission error is tested on an axle assembly triaxial real car load condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.127-137
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• 2009

Hypoid gears are widely used in rear drive and 4WD vehicle axles. Investigation of their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. The deflection test is performed in the actual gear mounting using completely processed gear. This test should cover the full operating range of gear loads from no load to peak load. Under peak load the contact pattern should extend to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. Transmission error is tested on an axle assembly triaxial real car load condition.

• Journal of Korean society of Dental Hygiene
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• v.20 no.3
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• pp.303-312
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• 2020

Objectives: The purpose of this study was to investigate the relationship between periodontal disease, number of remaining teeth with high-sensitivity C-Reactive protein in Korean adults aged 40 and older. Methods: The study used the Sixth Korea National Health and Nutrition Examination Survey (KNHANES VI-3), 2015. The study sample consisted of 3,883 aged 40 years or older who had completed the health survey and the health examination. Logistic regression analyses were performed to examine the odds ratios of high-sensitivity C-Reactive protein by periodontal disease and number of remaining teeth, adjusting for demographic characteristics, chronic diseases and oral health behavior-related variables. Results: When the demographic and chronic diseases were adjusted, the risk of high-sensitivity C-Reactive protein (hs-CRP) average 1.23 mg/L or higher was 1.36 times higher in patients with periodontal disease between the ages of 40 and 49, but it was not significant (OR=1.36; 95% CI=0.82-2.23). In addition, in the group of 0~23 remaining teeth aged 40~49 years, the risk of higher than the average 1.23 mg/L of high-sensitivity C-Reactive protein was 2.03 times higher (OR=2.03; 95% CI=1.10-3.74), and 1.49 times higher in 60~69 years (OR=1.07; 95% CI=1.04-2.76). Conclusions: This study found that periodontal disease and tooth loss in Korean adults aged 40 and older was significantly associated with high-sensitivity C-reactive protein.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.613-619
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• 2001

The aims of this study were to compare the accuracy, sensitivity and specificity of cnventional visual examination, radiography and a new laser fluorescence method, KaVo Diagnodent, for the detection of occlusal caries lesions. One hundred sound human premolars and molars which had no restorations or interproximal cavities were tested by three methods. Tooth lesions depth was assessed at histologic examination using Caries detector dye The following results were obtained. 1. Diagnodent show 7.8 in sound tooth, 25.4 in initial caries, 30.5 in enamel caries, and 53.8 in dentin caries with average score 2. Spearman and Pearson relation coefficient was high between tooth-specimen test with dye and Diagnodent(0.736, 0.619), visual examination(0.664, 0.666), and was low between tooth-specimen test with dye and radiographic examination(P<0.01, total) 3. Accuracy of occlusal caries was highest on Diagnodent(65%) and lowest on radiographic examination(35%) 4. In initial caries, the sensitivity and specificity of Diagnodent method was the highest. In enamel caries, the sensitivity of visual examination was the highest and specificity of Diagnodent method was the highest. In dentinal caries, the sensitivity and specificity of Diagnodent method was the highest and sensitivity of visual examination was the lowest.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.103-115
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• 1998

Adhesion of composite resin to tooth structure has been of tremendous signgicance in clinical dentistry. Due to the lack of adhesion between composite restorative resins and enamel and dentin, microleakage occurs at the tooth/restoration interface. This may lead to discoloration, secondary caries, marginal breakdown, postoperative sensitivity, and even pulpal pathology. According to extensive use of composite resin, every effort on improving bonding strength and reducing microleakage between a tooth and composite resin has been continued. This study was conducted to determine the difference in microleakage in enamel and dentin treated with air-abrasion, acid etching and combination when restored with composite resin. Class V cavities were prepared on 30 premolars. The specimens were divided into following groups. group 1:air-abrasion+Scotchbond Multi-purpose group 4 :air-abrasion+All-Bond 2 group 2:acid etching+Scotchbond Multi-purpose group 5 :acid etching+All-Bond 2 group 3:combination+Scotchbond Multi-purpose group 6 :combination+All-Bond 2 #combination:air-abrasion + acid etching The specimens were filled with Z-100 after application of Scotchbond Multi-purpose and All-Bond 2. Thermocycling was conducted by alternately dipping the specimens in $5^{\circ}C$ and $55^{\circ}C$ water for 30 seconds 500 times. 1% methylene blue was applied and the specimens were left for 24 hours at $37^{\circ}C$. After washing out the dye, the tooth was sectioned buccolingually along the axis. The sectioned surface was observed with stereoscope for dye penetration. The author has measured the microleakage in teeth prepared with air-abrasion, acid ethching and combination to study the difference in microleakage following different methods of tooth surface treatment and has come to following results. 1. In comparing microleakage between groups, group 1 and 4 showed statistically significant difference from group 2, 3, 5 and 6(p<0.05). There was no significant difference among group 2, 3, 5, 6(p>0.05) nor between group 1 and 4(p>0.05). 2. In comparing microleakage among tooth surface treatment methods, Air-abrasion group showed significantly more microleakage than acid etching group and combination(airabrasion + acid etching) group(p<0.05). Combination(acid etching+air-abrasion)group tended to show lesser microleakage than acid etching group, but this was not statistically significant(p>0.05). 3. In comparing microleakage between bonding agents, there was no statistically significant difference between Scotch bond Multi-purpose and All-Bond 2(p>0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.2
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• pp.143-152
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• 2023

Although tooth wear is a normal process due to aging, severe tooth wear causes various complications such as increased tooth sensitivity, loss of tooth structure, and pulp complications. In the treatment of patients with excessive tooth wear, the evaluation of loss of vertical occlusal dimension should be prioritized. If it is necessary to increase the vertical dimension to secure the restoration space, it is important to establish a treatment plan with the comprehensive analysis and determine the minimum vertical dimension elevation. In this case, 66-year-old male patient with severe worn dentition wanted to restore masticatory function and improve esthetic restoration. In order to determine the appropriate vertical dimension of the patient, we evaluated oral examination, radiographic examination, and diagnostic cast examination, and performed rehabilitation with minimum vertical dimension elevation. As a result of observation for 8 months, the definitive prosthesis was completed with contact of all teeth in centric occlusion, and proper anterior/posterior guidance. Through the above process, satisfactory aesthetic and functional outcomes were obtained.