• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.284-295
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• 1999

The purpose of this study was to measure and analyze the bond strength of bonded amalgam using dental adhesives and to compare this with light-curing composite resin. Sections 8mm in diameter were punched out from the labial surface of bovine anterior teeth. These were embedded in clear acrylic resin blocks with labial surface facing out. 55 specimens were made for enamel and dentin each. After dividing these into 5 groups, group 1: Superbond C&B, group 2: Panavia 21, group 3: All-Bond 2, group 4: Fuji I Glass Ionomer Luting Cement, group 5: Scotchbond Multi-Purpose(Restorative Z-100), molds with holes of 6.3mm in diameter and 1.5mm in depth were placed over the specimens. The exposed tooth surfaces were treated with adhesives and the molds were filled with amalgam. In group 5, the mold was filled with composite resin and light-cured for 40 seconds. The author measured all specimens for bond strength 24 hours after amalgam filing and analyzed fracture surfaces. The following results were obtained: 1. Among the dentin groups, groups 1, 2 and 4 showed significantly lower bond strength compared with group 5(P<0.05). 2. Among the enamel groups, group 4 showed significantly lower bond strength compared with group 5(P<0.05). 3. In group 2, 2D showed significantly lower bond strength compared with group 2E(P<0.05). Other adhesives showed no such differences in bond strength between dentin and enamel(P>0.05). 4. Cohesive failure was observed in groups 1E and 5D, while mixed failure was seen in groups 1 and 5. Only adhesive failures were noted in groups 2, 3, 4.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.3
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• pp.157-170
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• 2002

The purpose of this study is to analyze the shear bond strength according to kinds of surface treatment agents and resin cements after acid etching of IPS Empress 2. For this purpose, test groups were classified into silane-treated bonding groups, silica-coated group and Targis link applied group. Then, nine bonding groups in total, each three groups per kind, were prepared by using three kinds of resin cements-Panavia F, Variolink II and Rely-X ARC, and thirty test specimens per group were prepared. To examine any changes in the oral environment, the shear bond strength of each test specimen was measured after dipping test for 24 hours and for five weeks, respectively, in distilled water at $37^{\circ}C$ and performing heat cycle 10,000 times in total, each 2,000 times per week, during a five weeks of dipping, under the condition similar to the oral environment. The bond failure modes were also observed by means of a scanning electron microscope. The results are summarized as follows 1. Statically significant differences between the surface conditioning materials were observed. The shear strength of the silane treatment was the highest of all three types of surface treatments(p<0.001). 2. Shear strengths varied significantly for different types of resin luting agents. But bond strength of Targis link surface treatments were not significantly different(p<0.05). 3. No significant difference of bonding strengths was found between storage time conditions(24 hours and 5 weeks). Only group II, IV, VII, IX were significantly different(p<0.05). 4. After thermocycling, the shear bond strengths of all groups were significantly decreased (p<0.05). Group III, V, VI were no significantly different. 5. On the SEM observation of fractured surfaces, all groups were shown complex failure.

• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.526-536
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• 2008

The purpose of this study was to compare the effect of various dentin bonding systems on microtensile bond strength of immediate dentin sealing (IDS) and delayed dentin sealing (DDS). Eighteen extracted permanent molars were used in this study. The teeth for DDS group were restored with a provisional restorations, and immersed in saline solution for 1 week, and divided into 3 subgroups according to various dentin bonding adhesives; SB subgroup (3 step total-etch adhesive), SE subgroup (2 step self-etch adhesive), XE subgroup (1 step self-etch adhesive). In IDS group, the teeth were divided into 3 subgroups, and applied with bonding adhesives as in DDS group. The teeth were restored with provisional restorations, and immersed in saline solution for 1 week. Indirect composite disc was cemented with resin cement, and all specimens were subjected to microtensile bond strength. The data were statistically analyzed with oneway ANOVA and Student t-test. The results were as follows: 1. The IDS group showed significantly higher ${\mu}TBS$ than DDS group in 3 step total-etch and 2 step selfetch adhesive (p < 0.05). 2. In IDS and DDS group, 3 step total-etch adhesive showed the highest ${\mu}TBS$ value, followed by 2 step self-etch, and 1 step self-etch adhesive. In IDS group, the ${\mu}TBS$ value for 1 step self-etch adhesive was significantly different from those of the other subgroups (p < 0.05), and in DDS group, there were statistical differences in all subgroup (p < 0.05). 3. Failure modes of tested dentin bonding adhesives were mostly mixed failure and only 1 step self-etch adhesive showed adhesive failure.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.269-281
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• 2008

Fatigue or overload can result in mechanical problems of implant components. The mechanical strength in the implant system is dependent on several factors, such as screw and fixture diameters, material, and design of the fixture-abutment connection and abutment. In these factors, the last rules the strength and stability of the fixture-abutment assembly. There have been some previous reports on the mechanical strength of the fixture-abutment assembly with the compressive bending test or short-term cyclic loading test. However, it is restrictive to predict the long-term stability of the implant system with them. The purpose of this study was to evaluate the influence of the design of the fixture-abutment connection and abutment on the mechanical strength and failure mode by conducting the endurance limit test as well as the compressive bending strength test. Tests were performed according to a specified test(ISO/FDIS 14801) in 4 fixture-abutment assemblies of the Osstem implant system: an external butt joint with Cemented abutment (group BJT), an external butt joint with Safe abutment (group BJS), an internal conical joint with Solid abutment (group CJO), and an internal conical joint with ComOcta abutment (group CJT). The following conclusions were drawn within the limitation of this study. Compressive bending strengths were decreased in order of group BJS(1392.0N), group CJO(1261.8N), group BJT(1153.2N), and group CJT(1110.2N). There were no significant differences in compressive bending strengths between group BJT and group CJT(P>.05). Endurance limits were decreased in order of group CJO(600N), group CJT(453N), group BJS(360N), and group BJT(300N). 3. Compressive bending strengths were influenced by the connection and abutment design of the implant system, however endurance limits were affected more considerably by the connection design.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.207-215
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• 2005

This study was performed to evaluate clinical practicality of the rebonding method with flowable resin without the removal of the residual resin on the debonded theeth and debonded bracket base after debonding. The samples of the control group (group I) were rebonded with Transbond XT using the usual rebonding method after the residual resin was removed. At experimental group, the brackets were rebonded with Transbond XT(group II) and CharmFil Flow (group III) without removal of residual resin which is the possibility becoming the index (or rebonding to similar position With initial bonding. The Shear bond Strength of the each group was measured. Patterns of bonding failure were evaluated with modified ARI score. and the shear bond strength according to patterns of bonding failure at experimental group was compared. Between the control group $(6.51\pm1.21MPa)$ and the group II rebonded with Transbond XT $(6.30\pm1.01MPa)$ did not have significantly difference in the shear bond strength (p=0.534), and the shear bond strength of group II was Significantly lower 4han the group III rebonded With CharmFil Flow $(7.29\pm1.54 MPa)$ (P=0.009). At control group, there was not large difference if distribution of bending failure pattern. But at experimental group, bond failure did not occur in interface between the resin-enamel. and bond failure between the resin-bracket, within the resin was distributed similarly. There was not significantly difference in the shear bond strength according to patterns of bonding failure at experimental group (P>0.05) The result of this study showed that the method suggested in this study aid flowable resin as rebonding adhesive could be useful in clinically.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.290-298
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• 2004

In children, change in lifestyles such as an increase in participation of physical activities has increased the chance of receiving an injury, harming the child and their parents. This study was carried out to give basic information of traumatic injuries to the upper anterior teeth which can be used in prevention of future complications that may arise. From June, 2002 to May, 2003, of the 8,799 children in their primary and mixed dentition visiting Department of Pediatric Dentistry, College of Dentistry, Yonsei University 955 upper anterior teeth(primary 543, permanent 412) of 487 children(male 316, female 171) with traumatic injures to the upper incisors were studied. The results were as follows: 1. Trauma to the primary teeth prevailed at the age of 1-3 and to the permanent teeth at the age of 7. The male to female ratio was 1.85:1. 2. Trauma to the upper incisors for both the primary and permanent teeth occurred in the afternoon. Primary teeth were injured most frequently in the home(44.1%) and the permanent teeth outdoors, in the street(17.5%). 3. Both the primary and permanent teeth were most injured by fall-down injuries(39.8%, 12.9%), and next were collisions(22.2%, 6.0%). For the primary teeth, high fall, traffic accident, violence and sports are next in order, and for the permanent teeth, violence, sorts, traffic accidents were next. 4. Average number of 1.6 primary teeth and 2.8 permanent teeth were injured with the right central incisor most prevailing. 5. Crown fracture without pulpal exposure and subluxation injures were highest in frequency in both the primary and permanent teeth.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.208-221
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• 2007

The fracture toughness test is believed as a clinically relevant method for assessing the fracture resistance of the dentinal restoratives. The objectives of this study were to measure the fracture toughness $(K_{1C})$ and microtensile bond strength of dentin-resin composite interface and compare their relationship for their use in evaluation of the integrity of the dentin-resin bond. A minimum of six short-rod specimens for fracture toughness test and fifteen specimens for microtensile bond strength test was fabricated for each group of materials used. After all specimens storing for 24 hours in distilled water at $37^{\circ}C$, they were tensile-loaded with an EZ tester universal testing machin. Statistical analysis was performed using ANOVA and Tukey's test at the 95% confidence level, Pearson's coefficient was used to verify the correlation between the mean of fracture toughness and microtensile bond strength. FE-SEM was employed on fractured surface to describe the crack propagation. Fracture toughness value of Clearfil SE Bond (SE) was the highest, followed by Adper Single Bond 2 (SB), OptiBond Solo (OB), ONE-STEP PLUS (0S), ScotchBond Multi-purpose (SM) and there was significant difference between SE and other 4 groups (p < 0.05). There were, however, no significant difference among SB, OB, OS, SM (p > 0.05). Microtensile bond strength of SE was the highest, followed by SB, OB, SM, OS and OS only showed significant lower value (p < 0.05). There was no correlation between fracture toughness and microtensile bond strength values. FE-SEM examination revealed that dentin bonding agent showed different film thickness and different failure pattern according to the film thickness. From the limited results of this study, it was noted that there was statistically no correlation between K1C and ${\mu}TBS$. We can conclude that for obtaining the reliability of bond strength test of dentin bonding agent, we must pay more attention to the test procedure and its profound scrutiny.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.1-6
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• 2000

Dentinogenesis imperfecta is an inherited disorder of dentin formation, usually exhibiting an autosomal dominant mode of transmission. Type I dentinogenesis imperfecta occurs in patients afflicted with osteogenesis imperfecta. Type II dentinogenesis imperfecta is not associated with osteogenesis imperfecta. Type III dentinogenesis imperfecta (Brandywine type) occurs in a racial isolate area in the state of Maryland. In all three types, teeth of both dentitions are affected with variable clinical appearances. The teeth are opalescent with the color ranging from bluish-gray to brown to yellowish. The dentin is abnormally soft, providing inadequate functional support to the overlying enamel. Although the enamel is normal, it fractures or chips away easily, exposing the occlusal and incisal dentin. The exposed soft dentin often undergoes rapid and severe functional attrition. The teeth exhibit bulb-shaped crowns with constricted cementoenamel junctions and thin roots. The teeth will exhibit varying stages of obliteration of the coronal and root pulpal chambers. The cementum, periodontal ligament and supporting alveolar bone appear normal. The enamel is normal. The mantle dentin remains nearly normal, whereas the remaining dentin is severely dysplastic. The dentinal tubules are disoriented, irregular, widely spaced, and usually larger than normal.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.2
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• pp.225-234
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• 2018

The purpose of this study was to analyze the ratio and rate of apical closure when inducing root growth of necrotic immature permanent teeth using alternative triple antibiotics. 24 permanent teeth in the treatment group and 27 premolars in the control group were retrospectively studied using periapical radiographs for more than 300 days after the first visit. The difference in the growth rate between the two groups was statistically compared using the Mann-Whitney test at a significance level of 0.05. There were no statistically significant differences between the two groups in the first month and during months 1 - 3, 3 - 6, and 6 - 12. After 12 months, the cumulative rate of decrease in the apical foramen width in the treatment group was 50.59% and that in the control group was 71.82%, which revealed a significant difference between the two groups. There were significant differences in the rates of decrease in the apical foramen width after 3, 6 months, and later period in the treatment group, respectively. The cumulative rate of increase in the root dentin area presented no statistically significant differences between the treatment group and control group during the entire period of examination.