• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.560-568
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• 2007

This study was performed to compare the shear bond strength of primary enamel & dentin treated by AQ Bond $Plus^{TM}$ and G $Bond^{TM}$, recently developed 6th generation dentin bonding system, to that of Single $Bond^{TM}$ being widely used. Also by observing the resin tag under scanning electron microscope, Resin tags of each material were also observed under scanning electron microscope and compared to one another. The possibility of clinical application of All-in-One system which has an advantage to reduce chair-time for children with difficult behavior pattern was evaluated. The results obtained are as follows: 1. No statistically significant difference between groups was found in shear bond strength of primary enamel. 2. In primary dentin, the shear bond strength of AQ Bond $Plus^{TM}$ was $1.15\;{\pm}\;0.37\;MPa$, G $Bond^{TM}$ was $1.69\;{\pm}\;0.74\;MPa$ and Single $Bond^{TM}$ was $0.56\;{\pm}\;0.11\;MPa$. There were no statistical difference between AQ Bond $Plus^{TM}$ and G $Bond^{TM}$ and between G $Bond^{TM}$ and Single $Bond^{TM}$, whereas statistically significant difference was found between AQ Bond $Plus^{TM}$ and Single $Bond^{TM}$. 3. Under scanning electron microscope, resin tags observed in AQ Bond $Plus^{TM}$ and G $Bond^{TM}$ were very weak and tangled while strong and thick tags were shown with many lateral branches in Single $Bond^{TM}$. The result of the present study coupled with the advantages of less working time over the previous generation suggests that All-in-One system might be effectively used in adhesive dental procedures for primary teeth.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.741-755
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• 1995

Currently titanium is the material of choice for implants because of its biological acceptance. This high degree of biocompatibility is thought to result, in part, from the protective and stable oxide layer that presumably aids in the bonding of the extracellular matrix at the implant-tissue interface. Endosseous dental implants are interfaced with bone, connective tissue, and epithelium when implanted into the jaw bone. The soft tissue interface including connective tissue and epithelium is one of the most critical factors in the determination of implant maintenance and prognosis. For maintenance of failing or failed implants, it is essential to treat the implant fixture surface to remove bacterial endotoxins and make a surface tolerated by surrounding soft and hard tissues. In this study, the effect of mechanical treatment on titanium plasma sprayed implant on adhesiveness and proliferation of human gingival fibroblasts and changed surface characteristics were studied. titanium plasma sprayed discs manufactured by Friedrichsfeld company were treated with loaw speed stone bur, a rubber point and a jetpolisher. Its surface components were analyzed with Energy dispersive X-ray spectroscopy to evaluate whether the surface characteristics were altered or not. To observe the spreading pattern of the human gingival fibroblasts which attached to the all specimens author used the scanning electron microscope. The results were as follows : Pure titanium and plasma sprayed titanium, stone polished titanium showed titanium peak and small amout of aluminum, so there was no alteration on surface characteristics. Under the scanning electron microscopic examination in the initial attachment of human gingival fibroblast, there was a slight enhancement in pure titanium, stone polished titanium than plasma sprayed titanium. After 6 hours, the pure titanium and stone polished titanium showed human gingival fibroblasts were elongated and connected with numerous processes. Human gingival fibroblasts were more intimately attached on the pure titanium discs than on the other discs. The human gingival fibroblasts attached on the plasma sprayed titanium by thin and elongated processes. After 24 hours, the human gingival fibroblasts connected with each other via numerous processes and compeletly covered the pure titanium and stone polshed titanium discs. Human gingival fibroblasts had multiple point contacts with more long and thin lamellopodia and showed a little bare surface on plasma sprayed titanium discs.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.3
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• pp.156-161
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• 2012

Purpose: This study was conducted to obtain difference in fracture strength according to the diameter of one-body O-ring-type of mini implant fixture, to determine the resistance of mini implant to masticatory pressure, and to examine whether overdenture using O-ring type mini implant is clinically usable to maxillary and mandibular edentulous patients. Materials and methods: For this study, 13 mm long one body O-ring-type mini implants of different diameters (2.0 mm, 2.5 mm and 3.0 mm) (Dentis, Daegu, Korea) were prepared, 5 for each diameter. The sample was placed at $30^{\circ}$ from the horizontal surface on the universal testing machine, and off-axis loading was applied until permanent deformation occurred and the load was taken as maximum compressive strength. The mean value of the 5 samples was calculated, and the compressive strength of implant fixture was compared according to diameter. In addition, we prepared 3 samples for each diameter, and applied loading equal to 80%, 60% and 40% of the compressive strength until fracture occurred. Then, we measured the cycle number on fracture and analyzed fatigue fracture for each diameter. Additionally, we measured the cycle number on fracture that occurred when a load of 43 N, which is the average masticatory force of complete denture, was applied. The difference on compressive strength between each group was tested statistically using one-way ANOVA test. Results: Compressive strength according to the diameter of mini implant was $101.5{\pm}14.6N$, $149{\pm}6.1N$ and $276.0{\pm}13.4N$, respectively, for diameters 2.0 mm, 2.5 mm and 3.0 mm. In the results of fatigue fracture test at 43 N, fracture did not occur until $2{\times}10^6$ cycles at diameter 2.0 mm, and until $5{\times}10^6$ cycles at 2.5 mm and 3.0 mm. Conclusion: Compressive strength increased significantly with increasing diameter of mini implant. In the results of fatigue fracture test conducted under the average masticatory force of complete denture, fracture did not occur at any of the three diameters. All of the three diameters are usable for supporting overdenture in maxillary and mandibular edentulous patients, but considering that the highest masticatory force of complete denture is 157 N, caution should be used in case diameter 2.0 mm or 2.5 mm is used.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.2
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• pp.113-120
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• 2014

This study will evaluate the effectiveness of various pretreatments when fiber-reinforced composite (FRC) post is bonded to endodontically treated tooth with resin cement. Materials and methods: Canal shaping of FRC post (DT Light post, Size 3, Bisco Inc., Schaumburg, IL, USA) was performed on endodontically treated premolars at 1.5 cm from CEJ. Samples were divided into 6 groups of surface treatment after conventional washing and drying to the canal. Total of 24 FRC posts were randomly divided into 6 groups of surface treatment as follows: Group C: control - no surface treatment, Group A: airborne-particle abrasion (Cojet sand, 3M ESPE), Group S: silanization (Bis-silane, Bisco Inc.), Group M: universal primer (Monobond-plus primer, Ivoclar Vivadent Inc.), Group AS: silanization after airborne-particle abrasion, Group AM: universal primer treatment after airborne-particle abrasion. Pretreated fiber posts were cemented with resin-based luting material and photo-polymerized and cut to the thickness of 1 mm. Push-out test using a universal testing machine was performed. Bonding failure strength of post dislodgement was measured and the type of bonding failure was classified. Data were analyzed with Kruskal-Wallis test and multiple comparison groups were performed using Tukey HSD value of rank test (${\alpha}=0.05$). Results: Group AS showed significantly highest bonding strength. Group S, group AM, group A, and group M showed lower bonding strength in order. The control group showed the lowest bonding strength. Conclusion: Surface treatment with silane showed to be the most effective of the surface pretreatment methods for cementation of FRC post. Surface treatment with universal primer showed no significant difference compared with no surface treatment group as for bonding strength.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.470-478
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• 2008

Statement of problem: Use of all-ceramic prostheses fabricated with CAD/CAM systems is increasing in the dentistry. Marginal fidelity in production of all-ceramic restoration has important clinical implications and is a key consideration issue in CAD/CAM production as well. Purpose: The objective of this study was to analyse marginal fidelities of $Procera^{(R)}$ Allceram Crown. Material and methods: On 56 patients treated with $Procera^{(R)}$ system Allceram Crown at Dankook Dental Hospital, marginal discrepancies of 101 abutments were measured by stereomicroscope at coping and final restoration stages. Paired t-test and one-way analysis of variance on marginal discrepancy data were conducted to determine the presence of significant differences between measurement and measuring point stages. Results: Marginal discrepancies of final restoration ($45.82{\pm}30.84\;{\mu}m$) were lower than alumina coping ($53.84{\pm}38.83\;{\mu}m$). Furthermore, the differences were found to be statistically significant at 95% confidence level. Anterior marginal discrepancies were lower than posterior marginal discrepancies, but they were not statistically significant. Lingual marginal discrepancies were higher than other measurement sites, and the differences were found to be statistically significant at 95% confidence level. Conclusion: Within the conditions of this study, marginal fidelities of $Procera^{(R)}$ Allceram Crown were acceptable, and after porcelain build-up, marginal fitness improved over alumina coping. More careful scanning is needed for better results.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.520-527
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• 2008

Purpose: This study was conducted to evaluate the shear bond strength of composite resin to dentin when etched with laser instead of phosphoric acid. Material and methods: Recently extracted forty molars, completely free of dental caries, were embedded into acrylic resin. After exposing dentin with diamond saw, teeth surface were polished with a series of SiC paper. The teeth were divided into four groups composed of 10 specimens each; 1) no surface treated group as a control 2) acid-etched with 35%-phosphoric acid 3) Er:YAG laser treated 4) Er,Cr:YSGG laser treated. A dentin bonding agent (Adapter Single Bond2, 3M/ESPE) was applied to the specimens and then transparent plastic tubes (3 mm of height and diameter) were placed on each dentin. The composite resin was inserted into the tubes and cured. All the specimens were stored in distilled water at $37^{\circ}C$ for 24 hours and the shear bond strength was measured using a universal testing machine (Z020, Zwick, Germany). The data of tensile bond strength were statistically analyzed by one-way ANOVA and Duncan's test at ${\alpha}$= 0.05. Results: The bond strengths of Er:YAG laser-treated group was $3.98{\pm}0.88$ MPa and Er,Cr:YSGG laser-treated group showed $3.70{\pm}1.55$ MPa. There were no significant differences between two laser groups. The control group showed the lowest bond strength, $1.52{\pm}0.42$ MPa and the highest shear bond strength was presented in acid-etched group, $7.10{\pm}1.86$ MPa (P < .05). Conclusion: Laser-etched group exhibited significantly higer bond strength than that of control group, while still weaker than that of the phosphoric acid-etched group.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.375-390
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• 2009

Statement of problem: Implant supported overdenture is accepted widely as a way to restore edentulous ridge providing better retention and support of dentures. Various types of attachment for overdenture have been developed. Purpose: The purpose of this study was to investigate the influence of attachment type in implant overdentures on the biomechanical stress distribution in the surrounding bone, prosthesis and interface between implant and bone. Material and methods: Finite element analysis method was used. Average CT image of mandibular body(Digital $Korea^{(R)}$, KISTI, Korea) was used to produce a mandibular model. Overdentures were placed instead of mandibular teeth and 2mm of mucosa was inserted between the overdenture and mandible. Two implants($USII^{(R)}$, Osstem, Korea) were placed at both cuspid area and 4 types of overdenture were fabricated ; ball and socket, Locator, magnet and bar type. Load was applied on the from second premolar to second molar tooth area. 6 times of finite element analyses were performed according to the direction of the force $90^{\circ}$, $45^{\circ}$, $0^{\circ}$ and unilateral or bilateral force applied. The stress at interface between implants and bone, and prosthesis and the bone around implants ware compared using von Mises stress. The results were explained with color coded graphs based on the equivalent stress to distinguish the force distribution pattern and the site of maximum stress concentration. Results: Unilateral loading showed that connection area between implant fixture and bar generated maximum stress in bar type overdentures. Bar type produced 100 Mpa which means the most among 4 types of attachments. Bilateral loading, however, showed that bar type was more stable than other implants(magnet, ball and socket). 26 Mpa of bar type was about a half of other types on overdenture under $90^{\circ}$ bilateral loading. Conclusions: In any directions of stress, bar type was proved to be the most vulnerable type in both implants and overdentures. Interface stress did not show any significant difference in stress distribution pattern.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.231-242
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• 2008

Purpose: The purpose of this study was to investigate the bond strength of the core-veneer interface in all ceramic systems. Material and Methods: The all ceramic systems tested with their respective veneer were IPS Empress 2 with IPS Eris, IPS e.max Press with IPS e.max Ceram and IPS-e.max ZirCAD with IPS e.max Ceram. Cores (N=36, N=12/group, diameter: 10mm, thickness: 3mm) were fabricated according to the manufacturer's instruction and cleaned with ultrasonic cleaner. The veneer(diameter: 3mm, thickness: 2mm) were condensed in stainless steel mold and fired on to the core materials. After firing, they were again ultrasonically cleaned and embedded in acrylic resin. The specimens were stored in distilled water at $37^{\circ}C$ for 1 week. The specimens were placed in a mounting jig and subjected to shear force in a universal testing machine(Z020, Zwick, Germany). Load was applied at close to the core-veneer interface as possible with crosshead speed of 1.00mm/min until failure. Average shear bond strengths(MPa) were analyzed with a one-way analysis of variance and the Tukey test(${\alpha}=.05$). The failed specimens were examinated by scanning electron microscopy(JSM-6360, JEOL, Japan). The pattern of failure was classified as cohesive in core, cohesive in veneer, mixed or adhesive. Results: The mean shear bond strength($MPa{\pm}SD$) were IPS e.max Press $32.85{\pm}6.75MPa$, IPS Empress 2 $29.30{\pm}6.51MPa$, IPS e.max ZirCAD $28.10{\pm}4.28MPa$. IPS Empress 2, IPS e.max Press, IPS e.max ZirCAD were not significantly different from each others. Scanning electron microscopy examination revealed that adhesive failure did not occur in any all ceramic systems. IPS Empress 2 and IPS e.max Press exhibited cohesive failure in both the core and the veneer. IPS e.max ZirCAD exhibited cohesive failure in veneer and mixed 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.

• Korean Journal of Environmental Agriculture
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• v.35 no.4
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• pp.270-277
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• 2016

BACKGROUND: Significant amount of bisphenol A has been released from the manufacturing process of plastics, epoxy resins, dental material and flame retardants. Bisphenol A has been detected at trace levels in wastewater, surface water, landfill leachate and drinking water. However, the residual survey of bisphenol A has not been performed in agricultural reservoir beside agricultural environment cultivating crops. This study was conducted to monitor the residual bisphenol A in national agricultural reservoirs and understand a level of contamination of bisphenol A in the agricultural environment in Korea. METHODS AND RESULTS: The water and water sediment were collected at agricultural reservoirs in Chungnam, Chungbuk, Kyunggi, Jeonnam, Jeonbuk, Kyungnam and Kyungbuk province. Bisphenol A was analyzed by the LC-MS/MS with triple quad 4500. The recovery of water and water sediment in the agricultural reservoirs showed the level of 95.7~97.2% and 91.5~100.3%, respectively. CONCLUSION: Bisphenol A was detected at the level of $0.05{\mu}g/L{\sim}0.18{\mu}g/L$ and $0.1{\mu}g/kg{\sim}34{\mu}g/kg$ in water and water sediment of the reservoirs, respectively. Based on the results, the residue of bisphenol A will be tried in the crops surrounding these agricultural reservoirs where bisphenol A detected above $10{\mu}g/kg$ of bisphenol A.