• The Journal of the Korean dental association
• /
• v.13 no.5
• /
• pp.415-416
• /
• 1975

1. The author have had a case of class V and class Ⅲ combined carious lesion extended on to root surface of upper right lateral incisor. 2. The patient was 40 years old female. 3. After routine root canal treatment of the tooth, the gingival flap was made by vertical incision on gingival tissue between distal surface of upper right lateral incisor and mesial surface of upper right canine. 4. Cavity preparation and amalgam filling on the carious lesion were performed and the flap was sutured.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.8
• /
• pp.678-684
• /
• 2008

A general treatment is to restore abfraction lesions with dental filler materials to reduce stress concentration. A material should be selected from various dental products based on long term experiences of dentist or personal preference concerning filler methods. A quantitative criterion is necessary to make an evaluation of the results as dentists decide treatment methods and dental materials relying on their clinical experiences. The purpose of this study is to find an optimal restoration method and material for noncarious cervical lesions using the finite element method. An objective function was defined to minimize the sum of tension or compression stress. Trial-and-error and approximation were used to find an optimal restoration method. An optimal solution was to fill TetricFlow inside the lesion and Z100 in the remaining region. The most desirable thickness ratio of the two filler materials was 0.125 with trial-and-error and it was similar to the results of approximation, 0.121 and 0.132.

• Restorative Dentistry and Endodontics
• /
• v.33 no.1
• /
• pp.28-38
• /
• 2008

This study was to investigate the influence of composite resins with different elastic modulus, cavity modification and occlusal loading condition on the stress distribution of restored notch-shaped noncarious cervical lesion using 3-dimensional (3D) finite element (FE) analysis. The extracted maxillary second premolar was scanned serially with Micro-CT. The 3D images were processed by 3D-DOCTOR. ANSYS was used to mesh and analyze 3D FE model. A notch-shaped cavity and a modified cavity with a rounded apex were modeled. Unmodified and modified cavities were filled with hybrid or flowable resin. After restoration, a static load of 500N was applied in a point-load condition at buccal cusp and palatal cusp. The stress data were analyzed using analysis of principal stress. The results were as follows: 1. In the unrestored cavity, the stresses were highly concentrated at mesial CEJ and lesion apex and the peak stress was observed at the mesial point angle under both loading conditions. 2. After restoration of the cavity, stresses were significantly reduced at the lesion apex, however cervical cavosurface margin, stresses were more increased than before restoration under both loading conditions. 3. When restoring the notch-shaped lesion, material with high elastic modulus worked well at the lesion apex and material with low elastic modulus worked well at the cervical cavosurface margin. 4. Cavity modification the rounding apex did not reduce compressive stress, but tensile stress was reduced.

• Restorative Dentistry and Endodontics
• /
• v.25 no.1
• /
• pp.91-108
• /
• 2000

Most of cervical abrasion and erosion lesions show gingival margin where the cavosurface angle is on cementum or dentin. Composite resin restoration of cervical lesion shrink toward enamel margin due to polymerization contraction. This shrinkage has clinical problem such as microleakage and secondary caries. Several methods to diminish contraction stress of composite resin restoration, such as modifying cavity form and building up restorations in several increments have been attempted. The purpose of this study was to compare polymerization contraction stress of composite resin in Class V cavity subjected to cavity forms and placement methods. In this study, finite element model of 5 types of Class V cavity was developed on computer tomogram of maxillary central incisor. The types are : 1) Box cavity 2) Box cavity with incisal bevel 3) V shape cavity 4) V shape cavity with incisal bevel 5) Saucer shape cavity. The placement methods are 1) Incisal first oblique incremental curing 2) Bulk curing. An FEM based program for light activated polymerization is not available. For simulation of curing dynamics, time dependent transient thermal conduction analysis was conducted on each cavity and each placement method. For simulation of polymerization shrinkage, thermal stress analysis was performed with each cavity and each placement method. The time-temperature dependent volume shrinkage rate, elastic modulus, and Poisson's ratio were determined in thermal conduction data. The results were as follows : 1. With all five Class V cavifies, the highest Von Mises stress at the composite-tooth interface occurred at gingival margin. 2. With box cavity, V shape cavity and saucer cavity, Von Mises stress at gingival margin of V shape cavity was lower than the others. And that of box cavity was lower than that of saucer cavity. 3. Preparing bevel at incisal cavosurface margin decreased the rate of stress development in early polymerization stage. 4. Preparing bevel at incisal cavosurface margin of V shape cavity increased the Von Mises stress at gingival margin, but decreased at incisal margin. 5. At incisal margin, stress development by bulk curing method was rapid at early stage. Stress development by first increment of incremental curing method was also rapid but lower than that by bulk curing method, however after second increment curing final stress was the same for two placement methods. 6. At gingival margin, stress development by incremental curing method was suddenly rapid at early stage of second increment curing, but final stress was the same for two placement methods.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.7 s.196
• /
• pp.112-119
• /
• 2007

Cavities of Class V are caused by heavy occlusal loads due to bruxism and clenching habit. It is general to restore abfraction lesions with dental filler materials to reduce stress concentration. A material should be selected from various dental products based on long term clinical experiences or personal preference concerning filler methods. A quantitative criterion is necessary to make an evaluation of the results as dentists decide treatment methods and dental materials relying on their clinical experiences. The purpose of this study is to find an optimal restoration method and material for noncarious cervical lesions using the finite element method. An objective function was defined to minimize the sum of tensile and compressive stresses. Several models with different combinations of resins were suggested and compared in terms of the values of objective function. An optimal solution was to fill TetricFlow inside the lesion and Z100 in the remaining region with a thickness ratio of 0.125.

• Journal of Periodontal and Implant Science
• /
• v.39 no.1
• /
• pp.17-26
• /
• 2009

Purpose: The non-carious cervical lesion(NCCL) is a loss of tooth structure at the neck of affected teeth that is unrelated to tooth caries. The reported prevalence of NCCL varies from 5% to 85%. Prevalence and severity of lesions have been found to increase with age. They are becoming more significant as people live longer and become more aware of the importance of oral health. The purposes of this study were first, to examine the periodontal conditions associated with NCCL, and second, to investigate the clinical effects of class V restorations of NCCL on periodontal tissues. Materials and methods: The sample size was 982 teeth of 50 subjects(25 male, mean age $52{\pm}7$) who were seen at the Department of Periodontology, Pusan National University Hospital. At the baseline examination, clinical periodontal parameters were measured. After the initial examination, 24 patients who were absent from hypersensitivity were selected. The teeth with NCCL were randomly divided into the test and control groups. The teeth in the test group were restored with flowable resin; the control teeth were not restored. Six months later, the clinical examinations were repeated. The data were analyzed using the SPSS program. Results: The results were as follows: 1) NCCL occurred on 45.8% of examined teeth. The percentage of affected teeth was higher in maxillary and premolar teeth. 2) The shallow saucer type was the most common. 3) Teeth with NCCL had more gingival recession, lower attachment level, and higher incidences of bleeding on probing(BOP) and plaque than NCCL-free teeth. 4) Six months later, gingival recession, attachment level, the percentages of BOP and plaque in the test group were lower than in the control group(p<0.05). Conclusion: NCCLs were more found in maxillary teeth, especially in premolar teeth. The results suggest that the restoration of NCCL could affect some periodontal parameters favorably.

• Journal of Chest Surgery
• /
• v.6 no.1
• /
• pp.41-46
• /
• 1973

This is a report on four cases of atelectasis which were implicated as one case of mucoid impaction and three cases of blood clots in main bronchus. The 1st case was found to be massive atelectasis on Lt. entire lung due to mucoid impaction with pulmonary tuberculosis. This case was performed the Lt. pneumonectomy. There are contain-ing impacted yellowish-gray jelly like thick materials on the Lt. whole bronchial trees and pathologic findings were consistent with tuberculosis including caseation necrosis and multinucleated giant cell on whole left lung thoroughly in microscopic findings. The 2nd and 3rd case [25 years old female and 30 years old female] were diagnosed as one sided entire lung ateletasis which were led by accumulation of old blood clots on bronchus following incomplete expectoration of sudden massive hemoptysis from pulmonary tuberculosis lesion. These two cases were recovered by removal of blood clots and bronchial irrigation under bronchoscopy. Follow up chest film revealed well aeration. The 4th case [45 years old] was taken the removal of old blood clots and tissue debris under the bronchoscopy as bronchial obstruction following massive hemoptysis. The cytologic findings revealed the class III in fresh sputum and class 1V in bronchial irrigation which may suggest of malignancy. However, we could not found the causative lesions suggestive malignancy by the bronchography and other diagnostic measurements.

• Proceedings of the KACD Conference
• /
• 2008.05a
• /
• pp.184-197
• /
• 2008

This study was to investigate the influence of combining composite resins with different elastic modulus, and occlusal loading condition on the stress distribution of restored notch-shaped non-carious cervical lesion using 3D finite element (FE) analysis. The extracted maxillary second premolar was scanned serially with Micro-CT. The 3D images were processed by 3D-DOCTOR. ANSYS was used to mesh and analyze 3D FE model. A notch-shaped cavity was modeled and filled with hybrid, flowable resin or a combination of both. After restoration, a static load of 500N was applied in a point-load condition at buccal cusp and palatal cusp. The stress data were analyzed using analysis of principal stress. Results showed that combining method such that apex was restored by material with high elastic modulus and the occlusal and cervical cavosurface margin by small amount of material with low elastic modulus was the most profitable method in the view of tensile stress that was considered as the dominant factor jeopardizing the restoration durability and promoting the lesion progression.

• Restorative Dentistry and Endodontics
• /
• v.33 no.3
• /
• pp.184-197
• /
• 2008

This study was to investigate the influence of combining composite resins with different elastic modulus, and occlusal loading condition on the stress distribution of restored notch-shaped non-carious cervical lesion using 3D finite element (FE) analysis. The extracted maxillary second premolar was scanned serially with Micro-CT. The 3D images were processed by 3D-DOCTOR. ANSYS was used to mesh and analyze 3D FE model. A notch-shaped cavity was modeled and filled with hybrid, flowable resin or a combination of both. After restoration, a static load of 500N was applied in a point-load condition at buccal cusp and palatal cusp. The stress data were analyzed using analysis of principal stress. Results showed that combining method such that apex was restored by material with high elastic modulus and the occlusal and cervical cavosurface margin by small amount of material with low elastic modulus was the most profitable method in the view of tensile stress that was considered as the dominant factor jeopardizing the restoration durability and promoting the lesion progression.

• Childhood Kidney Diseases
• /
• v.7 no.2
• /
• pp.150-156
• /
• 2003

Purpose : Efforts to predict the clinicopathological outcome of IgA nephropathy have been made but have yielded conflicting results and have not helped in deciding the appropriate timing of the renal biopsy. In this study, we reviewed the predictive factors of clinicopathological outcome for finding out the criteria of renal biopsy timing of IgA nephropathy. Methods : Forty children diagnosed with biopsy proven IgA nephropathy at Wonju Christian Hospital were studied retrospectively, based on medical records. Results : Among 39 patients, 2 children progressed to higher serum creatinine level. One of them reached to the end stage renal disease within 2 year 7 months. According to WHO histopathological classification, there were 15 cases of class I, 14 cases of class II, 7 cases of class III, and 3 cases of class IV. In the mild histological classes(class I, II), gross hematuria was shown in 23 out of 29 children(P=0.02). In the severe histological classes(class III, IV), gross hematuria was noted in 4 out of 10(P>0.05). The tubulointerstitial changes were grade 1 in 24 cases, grade 2 in 4 cases, grade 3 in 8 cases, and grade 4 in 3 cases. With an increase in the tubulointerstitial grade, the 24 hour urine protein/albumin ratio increased. Serum creatinine less than 0.79 mg/dL could predict the lower grade(grade 1 and 2) of tubulointerstitial changes. But serum creatinine greater than 1.13 mg/dL could predict the higher grade(grade 3 and 4) of tubulointerstitial changes. In children with gross hematuria(n=27), serum creatinine was lower(0.78 vs 1.09 mg/dL, P=0.027), serum IgA was higher(316.3 vs 198.8 mg/dL), and the cases of lower WHO classification(I and II) were more common(23 vs 4, P=0.029) than the children with microscopic hematuria. Conclusion : Serum creatinine less than 0.79 mg/dL, macroscopic hematuria, and higher 24 hour urine protein/albumin ratio would predict the lower grade glomerulo tubulointerstitial lesion in IgA nephropathy and could be used as the criteria delaying the renal biopsy.