• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.8-19
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• 2009

The purpose of this study was to investigate the effects of four restorative materials under various occlusal loading conditions on the stress distribution at the CEJ of buccal. palatal surface and central groove of occlusal surface of endodontically treated maxillary second premolar, using a 3D finte element analysis. A 3D finite element model of human maxillary second premolar was endodontically treated. After endodontic treatment, access cavity was filled with Amalgam, resin, ceramic or gold of different mechanical properties. A static 500N forces were applied at the buccal (Load-1) and palatal cusp (Load-2) and a static 170N forces were applied at the mesial marginal ridge and palatal cusp simultaneously as centric occlusion (Load-3). Under 3-type Loading condition, the value of tensile stress was analyzed after 4-type restoration at the CEJ of buccal and palatal surface and central groove of occlusal surface Excessive high tensile stresses were observed along the palatal CEJ in Load-1 case and buccal CEJ in Load-2 in all of the restorations. There was no difference in magnitude of stress in relation to the type of restorations. Heavy tensile stress concentrations were observed around the loading point and along the central groove of occlusal surface in all of the restorations. There was slight difference in magnitude of stress between different types of restorations. High tensile stress concentrations around the loading points were observed and there was no difference in magnitude of stress between different types of restorations in Load-3.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.519-527
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• 1999

The purpose of this study was to estimate shear bond strength according to difference in luting cements and Targis surface treatment. 70 non-carious extracted human molars and Targis shade D210(Ivoclar, Liechtenstein) were used in the present study and they were randomly assigned into 7 experimental groups ; Group 1 : specimens were bonded with using vitremer(3M, U.S.A). Group 2, 4, 6 : specimens were not-treated with silane and bonded with Panavia 21(Kuraray Japan), Choice(Bisco, U.S.A.) and Variolink II(Vivadent, Liechtenstein) respectively Group 3, 5, 7 : specimens were treated with silane and bonded with Panavia 21, Choice and Variolink II respectively. After the surface treatment, the luting cement was mixed by manufacturer's recommendation and then applied between dentin and Targis and excess cement was removed by brush. All specimens were stored for 24 hrs in distiled water at $37^{\circ}C$. Shear bond strength for each group was then measured. To examine the failure patterns of targis to dentin, specimens were fabricated and observed under the SEM. The results were as follows ; 1. The mean shear bond strength of the groups using resin cements was significantly higher than that using resin-modified GI cements (P<0.05). 2. There is no significant difference in shear bond strength between Panavia 21 and Choice whether silane was used or not(P>0.05). However, bond strength for the groups using Variolink II was higher in the specimens not-treated with silane than the treated specimens (P<0.05). 3. There is no significant difference in bond strength among the groups using silane surface treatment and resin cement (group 3, 5, 7) (P<0.05). 4. The proportions of the specimens showing the mixed fracture failure were 20% in groups using Panavia 21 and Variolink II and 15% in group using Choice.

• The Journal of Advanced Prosthodontics
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• v.3 no.2
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• pp.90-95
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• 2011

PURPOSE. To compare the fracture resistance and the mode of failure of endodontically treated teeth restored with different post-core systems. MATERIALS AND METHODS. Root canal treatment was performed on 40 maxillary incisors and the samples were divided into four groups of 10 each. For three experimental groups post space preparation was done and teeth were restored with cast post-core (Group B), stainless steel post with composite core (Group C) and glass fiber post with composite core using adhesive resin cement (Group D). Control group (A) samples were selected with intact coronal structure. All the samples were prepared for ideal abutment preparation. All the samples were subjected to a load of 0.5 mm/min at $130^{circ}$.until fracture occurred using the universal testing machine. The fracture resistance was measured and the data were analyzed statistically. The fracture above the embedded resin was considered to be favorable and the fracture below the level was considered as unfavorable. The statistical analysis of fracture resistance between different groups was carried out with t-test. For the mode of failure the statistical analysis was carried out by Kruskal-Wallis test and Chi-Square test. RESULTS. For experimental group Vs control group the fracture resistance values showed significant differences (P<.05). For the mode of failure the chi-square value is 16.1610, which means highly significant (P=.0009) statistically. CONCLUSION. Endodontically treated teeth without post core system showed the least fracture resistance demonstrating the need to reinforce the tooth. Stainless steel post with composite core showed the highest fracture resistance among all the experimental groups. Teeth restored with the Glass fiber post showed the most favorable fractures making them more amenable to the re-treatment.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.120-128
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• 1990

The purpose of this study was to examine the effect of surface treatment on the flexural strength of glass ionomer cement with time elapsed. Glass ionomer cement (Fuji ionomer type II, (GC Co.) was used as experimental materials. Glass ionomer cement was placed in a beam-shaped teflon mold (3mm ${\times}$ 3mm ${\times}$ 25mm) that was rest on a glass plate. Another flat glass was placed on the top of the mold with pressure. After the cement was set, the specimens were divided into three groups and thirty two specimens in each group were surface-treated as follows: No treatment group: Specimens were no surface-treated and stored at $35.6^{\circ}C$ in distilled water. Fuji varnish application (FA) group: Specimens were surface-treated with Fuji varnish (GC Co.) and stored at $35.6^{\circ}C$ in distilled water. Vaseline storage (VS) group: Specimens were no surface-treated and stored at $35.6^{\circ}C$ in vaseline. The flexural strength was measured after I day, 1 week, 2 weeks, 4 weeks from the start of mixing using Instron Universal Testing Instruments. Results were as follows: 1. After 4 weeks, vaseline storage group exhibited the maximum flexural strength (p <0.0005). 2. The flexural strengths in no treatment group were slightly increased with time elapsed, but its difference was not significant, statistically. 3. The flexural strengths in Fuji varnish application group were increased with time elapsed (p <0.05). 4. The flexural strengths in Fuji varnish application group and vaseline storage group were greater than that in no treatment group (p <0.0005).

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.191-205
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• 1992

The purpose of this study was to evaluate the microleakage of class II composite resin inlays and compare them with the conventional light-cured resin filling restorations. Class II cavities were prepared in 60 extracted human molars with which cervical margins were located below 1.0mm at the cemento-enamel junction using No. 701 tapered fissure carbide bur. All of the prepared cavities were restored as follows and divided into 6 groups. Group I and 2 were restored using direct filling technique and group 3,4,5 and 6 were restored using direct inlay technique that was cemented with dual-cured resin cements. group I: Cavities were restored with light-curing composite resin, Brilliant Lux. group 2. Cavities were restored with light-curing composite resin, Clearfil PhotoPosterior. group 3: Cavities were restored with Clearfil CR Inlay and heat treated at $125^{\circ}C$ for 7 minutes. group 4: Cavities were restored with same material as group 3 and heat treated at $100^{\circ}C$ for 15 minutes. group 5: Cavities were restored with Brilliant (Indirect esthetic system) and heat treated at $125^{\circ}C$ for 7 minutes. group 6: Cavities were restored with same material as group 5 and heat treated at $100^{\circ}C$ for 15 minutes. All specimens were polished with same method and thermocycled between $6^{\circ}C$ and $60^{\circ}C$, then immersed in a bath of 2.0% aqueous solution of basic fuchsin dye for 24 hours. Dyed specimens were sectioned longitudinally and dye penetration degree was read on a scale of 0 to 4 by Tani and Buonocore's method 45). The results were as follows: 1. Microleakage was observed rather at the cervical margins than at the occlusal margins in all groups. 2. Composite resin inlay groups showed significantly less leakage than direct filling groups at the cervical margins (p < 0.001). 3. In composite resin inlay groups, there was no significant difference in microleakage between specimens by heat treating temperature and time (p > 0.05). 4. There was no significant difference in leakage between each groups at the occlusal margins (p > 0.05).

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.45-63
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• 1994

128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.247-256
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• 1998

To evalutate the change in shear bond strength according to dentin surface treatment, 4 materials were divided into control group(A) and experimental group(B). Group A was treated according to the instruction of manufacture. Group B was treated with 32% phosphoric acid. After dentin surface treatment, each material was bonded and stored in 100% humidity during 7 days, and then, the shear bond strength was evaluated. The results were as follows: 1. In the case of treatment according to the instruction of manufacture, the shear bond strength according to material showed Z-100 to be highest with 12.42 MPa, Compoglass had the lowest shear bond strength with 4.23 MPa and there was significant difference between Compoglass and Z-100, Dyract (p<0.01). 2. The group treated with 32% phosphoric acid showed lower shear bond strength than that of the group treated according to the instruction of manufacture but there was no statistical significance. 3. As a result of observation under SEM, the fracture pattern was a mixture of cohesive and adhesive failure in group 1, and there was more adhesive failure in group 2, and in group 3 and 4 there was cohesive failure of material or tooth structure. From the results above Dyract showed shear bond strength levels between resin and resin -modified glass ionomer but Compoglass showed much lower shear bond strength than that of resin-modified glass ionomer thus indicating that even though they are the same type of material they show evident differences in physical properties. And it is thought that the treatment of dentin surface with phosphoric acid did not increase the shear bond strength, unlike enamel.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.2 no.2
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• pp.33-40
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• 2007

Objectives : This study was peformed to evaluate the effect of Chuna Traction, Correction and conservative treatment. Methods : The patient was diagnosed as cervical bulging disc, protrusion and Uncovertebral joint arthrosis through Cervical spine MRI and treated with conservative treatment(Chuna, Acupunture etc.). We measured Visual Analog Score(VAS) and Range Of Motion(ROM) to evaluate treatment effects. Results and Conclusions : ROM of Cervical spine has improved. VAS score was also decreased.

• Journal of Korean Dental Science
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• v.9 no.1
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• pp.28-34
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• 2016

Purpose: The purpose of the present retrospective cohort study was to investigate the incidence of sinus perforation during endodontic microsurgery and to assess healing of cases with sinus perforation. Materials and Methods: Clinical and radiographic records were collected from patients who were treated with endodontic microsurgery in the Microscope Center of the Department of Conservative Dentistry at Yonsei University College of Dentistry, Seoul, Korea, between March 2001 and January 2016. To determine the incidence of sinus perforation, all cases involving maxillary premolar and molar teeth were assessed, and cases with perforation of maxillary sinus during the procedure were counted. To assess the outcome of the endodontic microsurgery, cases with sinus perforation were recalled at least 1 year after surgery. Result: Two hundred and forty-nine maxillary premolars and molars were treated with endodontic microsurgery. Among these cases, 16 cases had sinus perforations. Overall incidence of sinus perforation was 6.4%. Thirteen cases with sinus perforation were followed up for 1 year after endodontic microsurgery. Outcome assessment revealed that 2 of 13 cases with sinus perforation had failed. The success rate of endodontic microsurgery with sinus perforation was 84.6%. Conclusion: Endodontic surgery performed using microsurgical techniques decreases the risk of sinus perforation. Predictable outcomes of endodontic microsurgeries and healing of sinus membrane can be expected with adequate treatment steps and careful periodic follow-ups in cases with maxillary sinus perforations.

• Journal of Korean Physical Therapy Science
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• v.3 no.1
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• pp.843-853
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• 1996

The purpose of this study was to determine whether extension exercise is effective in reducing low back pain. Nine patients with low back pain were randomly assigened to one of two groups-one was an experimental group in which the patient were treated with extension exercise(McKenzie method) and conservative therapy. The other was a control group in which the patients were treated with conservative therapy only. Treatment was performed for a period of ten days during Which we examed each patient three times: the first exam was done at the begining of treatment, the second after fives days, and the third after ten days. We used 'The Oswestry low back pain disability questionnaire'(r=.99) as the examination tool. The results were as follows: 1. Both experimental and control groups showed nonsignificant differences before and after treatment, and the between group difference was also non-significant(P>.05). 2. There was no effective reduction of low back pain by MecKenzie's extension exercise(p>.05). We admit that our study protocol had several shortcomings. If they had been accounted for, the result might have been different. Further study should be done with a better experimental design, a larger sample, and a longer experimental duration.