Zeynep Yesil Duymus

Shear Bond Strength of Repair Composite Resin to an Acid-Etched and a Laser-Irradiated Feldspathic Ceramic Surface

OBJECTIVEnThe purpose of this study was to evaluate the shear bond strength of a repair composite resin to a feldspathic ceramic surface that had been either etched with 9.5% hydrofluoric acid (HFA), irradiated by an Er:YAG or Nd:YAG laser, or etched with 9.5% HFA after being irradiated by each laser type.nnnBACKGROUND DATAnNew findings have shown that combined laser irradiation and acid etching of a ceramic surface can be used to roughen ceramic surfaces.nnnMETHODSnSeventy-eight feldspathic ceramic discs were assigned to six surface treatment groups (n = 13): C, no treatment; HFA, 9.5% HFA etching; ER, Er:YAG laser irradiation; ND, Nd:YAG laser irradiation; ER + HFA, Er:YAG laser irradiation followed by HFA etching; ND + HFA, Nd:YAG laser irradiation followed by HFA etching. The surface of one disc from each treatment group was examined under a scanning electron microscope. After the surface treatments and silanization, a repair composite resin was applied to each disc using a commercial ceramic repair kit. Shear bond strength testing was then done after storing the specimens in distilled water for 24 h at 37 degrees C and thermocycling. Each ruptured specimen was examined under a stereoscopic light microscope.nnnRESULTSnThe highest shear bond strength was found after HFA etching, and the lowest was found after Er:YAG laser irradiation. HFA etching also caused the most pronounced changes of all the surface treatments. When HFA was applied after either laser irradiation, the fissures and cracks were larger than those seen on the only laser-irradiated surfaces.nnnCONCLUSIONSnHFA etching is the most effective surface treatment for increasing the shear bond strength between a repair composite resin and a feldspathic ceramic surface. The shear bond strength after laser irradiation can be increased by HFA etching, but the strength of the bond is still smaller than that after HFA etching alone.

Use of mouthguard rates among university athletes during sport activities in Erzurum, Turkey

The purpose of this study was to determine the attitudes of mouthguard users in Erzurum, Turkey. The participants appreciation in the use of protective devices, such as mouthguards, during sport activities was also evaluated. In this study, a 10-item questionnaire was distributed to 50 coaches and a 10-item questionnaire was distributed to 768 university athletes of three different sport modalities (basketball, soccer and volleyball) in the Atatürk University Sport Competitions. The Sport Competitions are composed of 20 faculty, except the faculty of dentistry. The result of the coaches questionnaires indicated that none of the athletes used mouthguards while participating in sports. Of the coaches, 64% had seen orofacial trauma in their athletes during sport activities and 76% believed that mouthguards prevented oral injuries. Of the coaches, 76% reported that university athletes should use mouthguards in sport activities. The result of the university athletes questionnaires revealed that the mouthguard utilization rate was 0%. Of all players, 78.1% were males (age 17-29) and 21.9% were females (age 18-23). Of all players, 7.31% had suffered from one or more type of oral injury while not wearing mouthguards. The results indicate that in Turkey, the use of mouthguards is rare in sports. It should be a combined duty of dentists, sports physicians, and coaches to encourage the use of mouthguards during training and sport activities. Doctors and dentists need to recommend a more intensive education of students in sports medicine and sports dentistry.

Microtensile Bond Strength of Resin Cement to a Feldspathic Ceramic

OBJECTIVEnThe purpose of this study was to evaluate the microtensile bond strength of resin cement to a feldspathic ceramic after treating the surface with (a) hydrofluoric (HF) acid, (b) air abrasion, (c) Er:YAG laser irradiation, (d) Nd:YAG laser irradiation, and (e) HF acid etching after either air abrasion or laser irradiation.nnnBACKGROUND DATAnIt is unknown whether the laser application or its combination with another treatment method can be used as a tool to roughen the surface of a feldspathic ceramic in order to increase the bond strength between the resin cement and ceramic surface.nnnMATERIALS AND METHODSnForty feldspathic ceramic blocks (Ceramco(TM)) were prepared and divided into eight equal groups (nu2009=u20095) according to the following surface treatments: no treatment; etching with 9.5% HF acid; air abrasion with 50u2009μm Al(2)O(3); Er:YAG laser irradiation; Nd:YAG laser irradiation; air abrasion plus acid etching; Er:YAG laser plus acid etching; and Nd:YAG laser plus acid etching. After surface treatment, a silane-coupling agent and resin cement (Panavia F(TM)) were applied to each block. After storing for 24u2009h at 37°C and thermocycling between 5°C and 55°C for 1000 cycles, the microtensile bond strength of each specimen was measured.nnnRESULTSnThe highest bond strength was obtained from HF acid etching. HF acid etching after each laser irradiation significantly increased the bond strength (pu2009<u20090.05). However, HF acid etching after air abrasion decreased bond strength when compared to air abrasion alone.nnnCONCLUSIONSnHF acid etching is the most effective surface treatment method for a feldspathic ceramic. However, laser irradiation with either the Er:YAG or Nd:YAG laser is not an adequate method for improving the bond strength of Panavia F. The laser application should be combined with HF acid etching.

Comparison of the metal-ceramic bond after recasting and after laser sintering

STATEMENT OF PROBLEMnFailure of the bond between metal and ceramic is common with metal ceramic prostheses.nnnPURPOSEnThe purpose of this in vitro study was to investigate how recasting affects the metal-ceramic bond strength for 1 base metal and 1 noble alloy compared with laser-sintered Co-Cr alloy by using a procedure based on ANSI/ADA Specification No. 38.nnnMATERIAL AND METHODSnOne laser-sintered (Co-Cr) and 2 metal (Co-Cr, Pd-Ag) alloys were used. Metal strips (25 × 3 × 0.5 mm) were obtained with 2 different methods: torch melting and laser sintering. Twelve alloy specimens were processed for each group. Vita VM13 porcelain layers (8 × 3 × 1.1 mm) were fabricated at the centers of the metal frameworks. Specimens containing 100% fresh alloy were used in the first casting group (control). Metal ceramic specimens were prepared for each alloy, and no new metal was added to the second and third castings. The findings were statistically analyzed and compared with a 2-way analysis of variance (ANOVA).nnnRESULTSnThe second casting of the noble alloy-ceramic specimen had the highest mean metal-ceramic bond strength in flexure. No significant differences were found between the laser-sintered Co-Cr and the Pd-Ag metal ceramic specimens after the first and third castings.nnnCONCLUSIONnAll groups had adequate porcelain bond strength, except C2 (second casting of Co-Cr alloy) and C3 (third casting of Co-Cr alloy). Co-Cr alloy fabricated with new laser-sintering techniques is a promising alternative for metal ceramic restorations. Further research is needed before its use can be advocated in the dental laboratory.

Evaluation of the flexural strength of dual-cure composite resin cements.

The aim of this study was to evaluate of flexural strength of some adhesive resin cements. Three dual-cure composite resin cements (Nexus 3; Variolink II, Panavia F) were prepared. The manufacturers mixing directions for the cements were followed. Adhesive resin cement was mixed, placed in the rectangular portion of the mold. Fifteen specimens were prepared for each cements. The cements were light-activated with light lamp for 40 s on both and top and bottom surfaces. The each cement specimens were divided into three groups according to time of storage and stored in distilled water for 24 h, 15, and 30 days. Total 45 specimens were stored at 37°C (98.6 0F) in distilled water for 24 h, 15, and 30 days prior to tests. The flexural strength was tested wıth a universal testing machine at a crosshead speed of 0.5 mm/min (0.02 in.) The maximum load was recorded as MPa. The results were analyzed by Analysis of Variance and Duncan test. The Panavia F resin cements content Bisphenol A was showed the highest flexural strength (80.80 MPa) (11.71 ksi) for 24 h. The lowest flexural strength was observed in Nexus 3 (51.00 MPa) (7.39 ksi). It was found significant interaction of material and time (p < 0.05). The types of cement and time of storage was statistically significant on the flexural strengths (p < 0.001).

Comparison to Color Stability Between Amine with Benzoyl Peroxide Includes Resin Cement and Amine-reduced, Amine-free, Lacking of Benzoyl Peroxide Resin Cements After Thermocycle

Objective: This study aims to compare the color change (ΔE) of 5 resin cements (Panavia SA, Panavia V5, RelyX U200, Variolink NLC clear and +1) after thermocycling. Changes in color of specimens were determined after 10,000 cycles of thermocycling by spectrophotometer in the CIELAB. Materials and Methods: Ceramic disks, simulating laminate veneers, with thicknesses of 0.5, 0.7, and 1.0 mm (A1, IPS e.max) were fabricated. Color differences (ΔE) between the control and test groups were calculated. Data were statistically analyzed by 2-way analysis of variance (ANOVA). Also, Tukey’s multiple comparison tests were applied to know the difference between the groups (α = 0.05). Results: The factors of cement type and thickness of ceramic showed significant influence on ΔE values (P < .05). After thermocycling, all resin cements, except benzoyl peroxide including resin cement (Pan SA), were showed clinically acceptable to color change limits (ΔE < 3.3). On evaluating the effects of ceramic thickness on color change after thermocyle aging, control group (no ceramic thickness) showed color change (P < .05) visually. Conclusion: Amine-reduced, amine-free and lacking benzoyl peroxide resin cement showed minimal color change and better color stability.

Effect of ceramic surface treatments on the bond strength of different composite resins

Abstract This study was aimed to observe the relationship between the different surface treatments and the bond strength of both composite based adhesive cement and zirconia ceramic. Thirty-two zirconia ceramic discs were fabricated by following the instructions of manufacturer (5 × 5 × 1.5 mm). Four subgroups were obtained from the specimens according to the specified surface treatments respectively: (a) C: control groups: no treatment; (b) SB: sandblasting with 125 μm aluminum oxide particles for 10 s; (c) SC: silica coating for 10 s; (d) Nd :YAG laser . The composite resin specimens Panavia F and Clearfil SA were introduced and polymerized to the treated bonding areas. Afterwards the specimens were stored in distilled water at 37 °C during 24 h, and the shear test was applied. The data were statistically analyzed by ANOVA and Duncan tests. The bond strength was stated significantly higher in silica coating/Panavia F group (23.35 MPa). The lowest bond strength was stated in control groups cemented with Clearfil SA (12.25 MPa). As a result it was determined that the bond strength has affected the both surface treatments and cement types (p < 0.001). The silica coating –treated zirconia ceramic recorded a significant increase in mean bond strength values.

Effect of polymerization cycles on flexural strengths and microhardness of different denture base materials

The purpose of this study was to evaluate the effect of different polymerization cycles on the flexural strengths and microhardness of two denture base materials (Meliodent and Paladent). Heat-polymerized acrylic resin specimens (65.0 mm long×10.0 mm wide×2.5 mm in height) were prepared using different short and long polymerization cycles. After the specimens had been polymerized, they were stored in distilled water at 37±1°C for 24 h. Flexural strength test was performed at a cross-head speed of 5 mm/min and Vickers microhardness was measured. Data were analyzed with a 1-way analysis of variance followed by Tukey test, and Student t-test (α=0.05). The flexural strengths and microhardness were significantly different between Meliodent and Paladent (p<0.05). Significant differences were found among the polymerization cycles in terms of flexural strengths and microhardness (p<0.05). Polymerization with G cycle may be suggested for Meliodent and H cycle may be suggested for Paladent.

Influence of impression materials on choice of dental stone and improved dental stone

Abstract The surface hardness and compressive strength of dental stone and improved dental stone were investigated when crystallised in contact with impression materials. Vickers hardness tests were performed at 45 min, 2 h and 24 h, and compressive strength tests were performed at 24 h after the beginning of stone mixing. For the surface hardness of stone models, the impression material type, stone type and measurement time were found statistically significant (p<0·001) and for the compressive strength, the impression material type and stone type were found statistically significant (p<0·001). Within the measurement times, the hardness values were statistically different from each other. The highest hardness values were obtained from the 24 h measurements, followed by the 2 h measurements, while the lowest hardness values were obtained from the 45 min measurements. Specimens obtained from improved dental stone showed higher hardness values and compressive strength than those from dental stone.