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    Amalgam repair: Evaluation of bond strength and microleakage
    (OPERATIVE DENTISTRY INC, 2002) Ozer, F; Unlu, N; Ozturk, B; Sengun, A
    This study evaluated the tensile bond strength of "repaired" amalgams and compared the degree of microleakage. Amalgam (Cavex avalloy) was condensed into plastic tubes (3 mm in diameter, 10 mm. in height) to the half-length. After storage in water at 37degreesC for two days, the remaining parts of tubes were filled with amalgam (A), cavity varnish (CV)+A, Liner Bond 2V (LB2V)+A, 3M Opal Luting Cement (3MOLC)+A, Panavia F(PF)+A, Metabond(MB)+A, Fuji BondLC(FB)+A, HytacOSB(HOSB)+Hytac Aplitip (H), Liner Bond2V+Clearfil AP-X(CAP). The bond strengths for 15 samples of each restoration group were determined. For the microleakage study, MOD cavities of 90 extracted human premolars were used. The distal half of cavities were filled with amalgam. After storage in water at 37degreesC for two days, the mesial half of the cavities were filled to simulate a clinical repair. The "repair" was placed using the procedures applied in the bond strength study. The teeth were stained with basic fuchsine (0.5%), sectioned and evaluated for dye penetration. In both parts of study, the data were analyzed by ANOVA and Duncan's multiple range tests. Bond strength values (MPa) were: A+PF+A 3.84+/-1.08, A+LB2V+A 3.15+/-0.97, A+LB2V+CAP 3.05+/-0.53, A+MB+A 2.86+/-0.88, A+HOSB+H 2.58+/-0.51, A+3MOLC+A 2.11+/-0.75, A+FB+A 0.68+/-0.59. The repaired A+A and A+CV+A groups were separated before testing. The A+PF+A group showed the highest bond strength (p<0.05). Microleakage in the cervical margins of repaired restorations was lower in the amalgam groups than microleakage in the resin composite and compomer groups. PF, MB, 3MOLC and FB performed better at the amalgam "repair" interface. The A+LB2V+A group showed no microleakage at both the occlusal and gingival test regions.
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    An evaluation of surface hardness, roughness and wear of restorative composites, porcelain, and enamel following abrasion by enamel
    (TRANS TECH PUBLICATIONS LTD, 2004) Unlu, N; Donmez, N; Sengun, A; Ozer, F
    This study was performed to evaluate wear, surface hardness and roughness characteristics of light cured restorative composites, porcelain and enamel when opposed by human enamel. Five composite resins (3MSilux, ClearfilAP-X, 3MFiltek Z250, Pekalite, SureFil), one ceramic (VitadurAlpha) and enamel were selected as experimental materials. The antagonist abrasives were made by using buccal enamel of anterior teeth. Ten rectangular specimens were prepared for each material. The at the beginning of the study, the mean weight, roughness and hardness values of specimens were obtained. Then the specimens were opposed by human enamel and subjected to 20.000 sliding cycles in a prototype wear machine. Surface characteristics and final weights of each materials were recorded and compared to the values obtained at the beginning. Statistically significant differences were found among the hardness and roughness of materials (p<0.05). After wear procedure, surface hardness of all materials increased. There was not any significant difference among the wear values of materials and enamel.
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    Microtensile bond strength of two resin composite materials placed with direct and indirect techniques under simulated pulpal pressure
    (QUINTESSENCE PUBLISHING CO INC, 2005) Sengun, A; Unlu, N; Ozturk, B; Ozer, F
    Purpose: The aim of this in vitro study was to compare the dentin bond strength of directly and indirectly inserted composite restorations. Materials and Methods: Twenty extracted human mandibular molars were prepared to form a flat occlusal dentin surface using an Isomet saw under water. Five-mm-thick composite restorations (Filtek Z 250 and Clearfil AP-X) were placed on the dentin surfaces by direct or indirect techniques. The direct restorations were bonded with Single Bond and Clearfil SE Bond bonding agents. Indirect restorations were cemented with two composite luting cements (3M Opal Luting Cement and Panavia F). All restorative procedures were applied under simulated pulpal pressure (15 cm H2O). Each tooth was then vertically sectioned with an Isomet saw through the composite buildups and the dentin. Thus, for microtensile testing, 0.65 x 0.65 mm specimens were obtained from pulpal and remote dentin regions. The results were analyzed according to the regional dentinal surfaces (pulpal and remote dentin). For statistical analyses, two-way ANOVA and Duncan post-hoc tests were used (p < 0.05). Results: Direct application of Clearfil AP-X showed that tensile bond strengths were higher than those obtained for directly and indirectly applied Filtek Z 250 and indirectly applied Clearfil AP-X. No significant difference in tensile bond strengths was demonstrated between pulpal and remote dentin (p > 0.05). Conclusion: It is concluded that the bond strengths of resin luting cements to dentin need further improvement.
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    Shear bond strengths of tooth fragments reattached or restored
    (BLACKWELL PUBLISHING LTD, 2003) Sengun, A; Ozer, F; Unlu, N; Ozturk, B
    This study investigated the shear bond strengths of sectioned human mandibular incisor edge fragments reattached using luting cements, bonding agents or restored with composite resins. Seventy teeth were randomly distributed among six experimental groups and a control group. Leaving half of the anatomic crowns exposed, the teeth were embedded in self-cure acrylic resins with the exposed part then sectioned. The fragments in groups 1-4 were bonded to their respective teeth using Clearfil Liner Bond 2V, Scotch Bond Multi Purpose Plus, Panavia-F and 3M Opal Luting cement. The 5th and 6th groups were restored with composite resins (Silux 3M and Clearfil AP-X) using their bonding agents (Single Bond and Clearfil SE Bond). The results indicated that reattachment of fractured incisal fragments by using new generation bonding agents was effective against shear stresses, comparable with the intact teeth. Instead of restoration with composite resins therefore reattachment of a fractured fragment might be more preferable in cases of dental trauma.
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    Surface roughness and hardness of some dental ceramics and restorative resins
    (TRANS TECH PUBLICATIONS LTD, 2004) Karakaya, S; Unlu, N; Ovecoglu, HS; Ozer, F
    The aim of this study was to compare the surface hardness and roughness of seven composite resins AElite LS(AE), Clearfil Poto Posterior(CPP), SureFil (SF), Tetric Ceram (TC), Artglass (AG), Admira (AD), Estenia (ES)) and two ceramic materials (Vitadur Alfa (VA), Finesse(FI)). The composite speciemens were cured in cylindirical brass molds (4mm, in diameter and 2 mm in depth) against glass according to manufacturers' directions and polished. The ceramic specimens were prepared in same diameters, glazed. Hardness was determined at two different sites on one side specimens and the mean value was calculated as Vicker's Hardness Numbers (VHN). Surface roughness (SR) was measured tree times as Ra (mum) on each specimen and mean roughness values were obtained. For statistical analyses Mann Whitney U test was used. Surface roughness values of CPP, ES were very close to that of VA. Their surface roughness values were significantly higher than other materials. VHN of ES and AG were significantly lower than that of two ceramic materials. The surface hardness of ES was significantly harder than composite resins (P<0.05)
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    Three-year clinical evaluation of fiber-reinforced composite fixed partial dentures using prefabricated pontics
    (QUINTESSENCE PUBLISHING CO INC, 2006) Unlu, N; Belli, S
    Purpose: The purpose of this study was to evaluate the clinical performance of surface-retained adhesive composite fixed partial dentures reinforced by an ultra-high molecular weight polyethylene (UHMWP) fiber (Ribbond THM). Materials and Methods: Twenty-three surface-retained fiber reinforced composite (FRC) fixed partial dentures (FPD) were placed by two operators in 23 patients, each with a single missing tooth. The restorations included prefabricated composite resin pontics, and no preparations were done on the lingual surfaces of the abutment teeth. The patients were recalled for examinations every year for up to 3 years. Restorations were evaluated directly using the modified Ryge criteria. The minimum observation period was 1 year and the maximum observation period was 3 years. Results: At baseline, 23 restorations were graded as Alpha for all parameters. At one year and two years (n = 21), three Bravos for wear resistance and surface texture/gingival inflammation and two Bravos for color match were observed. Twenty-one of 23 restorations were retained at the end of two years (91.3%) and 78.3% were retained after a maximum of 3 years. Conclusion: The results of this clinical study suggest that UHMWP FRC FPDs are quite acceptable at least for three years. However, further clinical investigations are still needed for improved long-term clinical performance.