• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.2
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• pp.549-558
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• 1996

Light-cured orthodontic composite resin has been widely advertised recently for use in bonding brackets. However, the curability of light-cured resin when light waves are diffused through metal brackets in questionable. The purposes of this study were to evaluate shear bond strength and failure patterns of visible light-cured resin(Lightbond) and chemically cured-resin(Mono-Lok 2), and to determine the relative value of light-cured resin as an alternative to conventional chemically cured resin. Each of the two resins was tested on twenty extracted human first premolars. Standard edgewise metal brackets were bonded to the teeth in accordance with the manufacturers' recommendation. After bonding, the teeth were stored for 24 hours at $37^{\circ}C$, 100% humidity. The shear bond strength was tested with a universal testing machine(Instron 4302), at 0.5mm/min crosshead speed. After debonding, brackets and enamel surfaces were examined with a scanning electron microscope and a stereoscopic microscope. The results were as follows : 1. Metal brackets bonded with Lightbond showed statistically higher shear bond strength than metal brackets bonded with Mono-Lok2. 2. The predominant failure site in Lightbond was the enamel-resin interface, and in Mono-Lok 2 it was the resin itself. 3. Enamel cracks were not found in any specimen. The above results suggest that direct bonding of metal brackets to enamel with light-cured resin bonding agent can be used effectively in clinics.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.4
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• pp.582-610
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• 1992

The long-term success of any dental implant is dependent upon the optimization of stresses which occur during oral function and parafunction. Especially, it has been suggested that there is an unique set of problems associated with joining an osseointegrated implant and a natural tooth with a fixed partial denture. For this particular case, although many literatures suggest different ways to avoid high stress concentrations on the bone surrounding the implant under static and dynamic loading conditions, but few studies on the biomechanical efficacy of each assertion have been reported. The purpose of this investigation was to evaluate the efficacies of clinically suggested methods on stress distribution under static load and shock absorption under dynamic load, using two dimensional finite element method. In FEM models of osseointegrated implant-natural tooth supported fixed partial dentures, calculations were made on the stresses in surrounding bone and on the deflections of abutments and superstructure, first, to compare the difference in stress distribution effects under static load by the flexure of fastening screw or prosthesis, or intramobile connector, and second, to compare the difference in the shock absorption effects under dynamic load by intramobile connector or occlusal veneering with composite resin. The results of this analysis suggest that : 1. Under static load condition, using an implant design with fastenign screw connecting implant abutment and prosthesis or increasing the flexibility of fastening screw, or increasing the flexibility of prosthesis led to the .increase in height of peak stresses in cortical bone surrounding the implant, and has little effect on stress change in bone around the natural tooth. 2. Under static load condition, intramobile connector caused the substantial decrease in stress concentration in cortical bone surrounding the implant and the slight increase in stress in bone around the natural tooth. 3. Under dynamic load condition, both intramobile connector and composite resin veneering showed shock absorption effect on bone surrounding the implant and composite resin veneering had a greater shock absorption effect than intramobile connector.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.229-235
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• 2015

Objectives: To determine and compare the fracture resistance of endodontically treated maxillary central incisors restored with different posts and cores. Materials and Methods: Forty-eight upper central incisors were randomly divided into four groups: cast post and core (group 1), fiber-reinforced composite (FRC) post and composite core (group 2), composite post and core (group 3), and controls (group 4). Mesio-distal and bucco-lingual dimensions at 7 and 14 mm from the apex were compared to ensure standardization among the groups. Twelve teeth were prepared for crown restoration (group 4). Teeth in other groups were endodontically treated, decoronated at 14 mm from the apex, and prepared for posts and cores. Resin-based materials were used for cementation in groups 1 and 2. In group 3, composite was used directly to fill the post space and for core build-up. All samples were restored by standard metal crowns using glass ionomer cement, mounted at $135^{\circ}$ vertical angle, subjected to thermo-mechanical aging, and then fractured using a universal testing machine. Kruskal-Wallis and Mann-Whitney U tests were used to analyze the data. Results: Fracture resistance of the groups was as follows: Control (group 4) > cast post and core (group 1) > fiber post and composite core (group 2) > composite post and core (group 3). All samples in groups 2 and 3 fractured in restorable patterns, whereas most (58%) in group 1 were non-restorable. Conclusions: Within the limitations of this study, FRC posts showed acceptable fracture resistance with favorable fracture patterns for reconstruction of upper central incisors.

• The Journal of the Korean dental association
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• v.54 no.1
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• pp.21-26
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• 2016

The requirements for the successful treatment of all-ceramic restorations are not so different from the ones of conventional restorations. "The provisional restoration followed by an adequate tooth reduction" and "the accurately fitting prostheses with corresponding to final impression" can be the examples of them. Nevertheless, the one which all-ceramic restorations are distinguished from conventional restorations is the additional procedure of so called "bonding". In addition to the application of resin cement between "inner surface of restoration and outer surface of abutment", bonding technology can be also applied to the treatment process of "Post and Core" in particular if the abutments are non-vital teeth. Core build-up for all-ceramic crown is conducted with fiber post and tooth colored composite by considering the properties of the restorations transmitting light. I would like to share my clinical experience about "silica based ceramic and non silica based ceramic restoration.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.26 no.1
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• pp.39-51
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• 2017

In order to solve the problem of repositioning the old hader bar attachment and to restore the non-esthetic facial profile and improper occlusion of the edentulous patient due to inadequate jaw relation, determination of vertical dimension of occlusion and tooth arrangement were performed similar to the natural teeth before the teeth loss. In addition to improving the esthetics by restoring the inadequate facial appearance, the composite resin was used to maximize the patient's secondary esthetic satisfaction with the denture.

• The Journal of the Korean dental association
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• v.57 no.10
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• pp.588-594
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• 2019

The fusion is an anomalous union of two or more tooth germ at some stage in the development process resulting in a decreased number of teeth in the dental arch. Fusion is common odontogenic anomaly but triplication of primary teeth is a rare phenomenon. We report a case of a 3 - year - old girl who visited our clinic for the pain on maxillary anterior tooth. The patient was diagnosed by the fusion of a the maxillary primary right central and lateral incisor with a supernumerary tooth and caries of dentine. And then, Endodontic treatment and composite resin restoration were performed on the triple teeth. After follow-up of 6 months period, there was no marked complications.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.46-52
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• 2009

Statement of problem: Recently, titanium has become popular as superstructure material in implant dentistry because titanium superstructure can be easily milled by means of computer-aided design and manufacture (CAD/CAM) technique. But retention form such as nail head or bead cannot be cut as a result of technical limitation of CAD/CAM milling and bond strength between titanium and porcelain is not as strong as that of conventional gold or metal alloy. Purpose: The objective of this study was to evaluate the shear bond strength of three different materials: heat curing resin, composite resin, porcelain which were bonded to grade II commercially pure Titanium (CP-Ti). Material and methods: Thirty seven CP-Ti discs with 9 mm diameter, 10 mm height were divided into three groups and were bonded with heat curing resin (Lucitone 199), indirect composite resin (Sinfony), and porcelain (Triceram) which were mounted in a former with 7 mm diameter and 1 mm height. Samples were thermocycled for 1000 cycles at between $5-55^{\circ}C$. Shear bond strength (MPa) was measured with Instron Universal Testing Machine with cross head speed of 1 mm/min. The failure pattern was observed at the fractured surface and divided into adhesive, cohesive, and combination failure. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (${\alpha}=0.05$). Results: Lucitone 199 ($17.82{\pm}5.13\;MPa$) showed the highest shear bond strength, followed by Triceram ($12.97{\pm}2.11\;MPa$), and Sinfony ($6.00{\pm}1.31\;MPa$). Most of the failure patterns in Lucitone 199 and Sinfony group were adhesive failure, whereas those in Triceram group were combination failure. Conclusion: Heat curing resin formed the strongest bond to titanium which is used as a CAD/CAM milling block. But the bond strength is still low compared with the bond utilizing mechanical interlocking and there are many adhesive failures which suggest that more studies to enhance bond strength are needed.

• The korean journal of orthodontics
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• v.43 no.4
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• pp.186-192
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• 2013

Objective: To analyze the fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro. Methods: Roots of human mandibular central incisors were covered with silicone, mimicking the periodontal ligament, and embedded in polymethylmethacrylate. The specimens (N = 50), with two teeth each, were randomly divided into five groups (n = 10/group) according to the retainer materials: (1) Interlig (E-glass), (2) everStick Ortho (E-glass), (3) DentaPreg Splint (S2-glass), (4) Ribbond (polyethylene), and (5) Quad Cat wire (stainless steel). After the recommended adhesive procedures, the retainers were bonded to the teeth by using flowable composite resin (Tetric Flow). The teeth were subjected to 10,00,000 cyclic loads (8 Hz, 3 - 100 N, $45^{\circ}$ angle, under $37{\pm}3^{\circ}C$ water) at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (${\times}40$ magnification). Data were analyzed by one-way analysis of variance. Results: All the specimens survived the cyclic loading. Their mean debonding forces were not significantly different (p > 0.05). The DentaPreg Splint group (80%) showed the highest incidence of complete adhesive debonding, followed by the Interlig group (60%). The everStick Ortho group (80%) presented predominantly partial adhesive debonding. The Quad Cat wire group (50%) presented overlying composite detachment. Conclusions: Cyclic loading did not cause debonding. The retainers presented similar debonding forces but different failure types. Braided stainless steel wire retainers presented the most repairable failure type.

• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.69-79
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• 1983

This study was undertaken to evaluate the effects of varnish application and thermocycling on the marginal leakage. 240 cavities of Class V were prepared on the 120 extracted premolars, and the cavities were filled with amalgam, Heliosit$^{(R)}$, and Hipol$^{(R)}$ after application of Copalite$^{(R)}$ or Duraphat$^{(R)}$. All specimens were immersed in methylene blue solution for 24 hours after thermocycling at $4^{\circ}C$ and $60^{\circ}C$, embedded in acrylic resin, and sectioned with low speed saw into two parts. The sectioned specimens observed with the metallurgical microscope. The following results were obtained: 1. The marginal seal was more effective in the amalgam-filled cavities after application of Copalite$^{(R)}$ threetimes or an application of Duraphat$^{(R)}$ varnish than in those without varnish applications. 2. Of the composite resin-filled cavities, the leakage of the varnish applied cases showed much more than without application. 3. There was no significant difference in the effect of marginal sealing between Copalite$^{(R)}$ and Duraphat$^{(R)}$ applications. 4. There was a significant difference in the degree of the marginal leakage of amalgam-filled cavities between the groups of thermocycling times, but no significant difference in the resin-filled cavities. 5. There was no significant difference in the degree of the marginal leakage between the Heliosit$^{(R)}$ and the Hipol$^{(R)}$ resin-filled cavities.

• The Journal of Advanced Prosthodontics
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• v.9 no.1
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• pp.57-66
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• 2017

PURPOSE. Cementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin. MATERIALS AND METHODS. Ninety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders ($3{\times}3\;mm$) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed. RESULTS. Initial and repeated bond strengths to enamel were similar for all the groups. The first ($15.3{\pm}2.2\;MPa$) and second ($10.4{\pm}2.2\;MPa$) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001). CONCLUSION. All resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.