Özlem Acar

Effect of different surface-cleaning techniques on the bond strength of composite resin restorations

STATEMENT OF PROBLEM Different techniques have been suggested for cleaning dentin surfaces after the removal of an interim prosthesis and before the application of a bonding agent. How different surface-cleaning techniques affect the bond strength of the composite resin restorations is not clear. PURPOSE The purpose of this study was to investigate the effects of different surface-cleaning techniques on the bond strength of composite resin restorations and the surface topography of the prepared tooth surfaces. MATERIAL AND METHODS The occlusal surfaces of 25 molars were ground until the dentin was exposed. A bonding agent and interim cement were applied on the teeth. The teeth were divided into 5 groups (n=5) according to the method used for surface-cleaning (microairborne-particle abrasion, alcohol, rubber-rotary instrument, desiccating agent, and control). Once the surfaces of the teeth had been cleaned, the same bonding material was applied to the teeth. A 5-mm-thick composite resin layer was built up. Each specimen was sectioned to microbars, and 6 centrally located beams were selected for microtensile testing (n=30) (1.10 ±0.10 mm). The data were statistically analyzed with 1-way ANOVA (1-sample Kolmogorov-Smirnov test). The Bonferroni test was used for significantly different groups (α=.05). One specimen from each group was observed under a scanning electron microscope and an atomic force microscope. Energy dispersive x-ray analysis also was performed. RESULTS Bond strength values were in the following descending order: microairborne-particle abrasion, desiccating agent, alcohol, rubber-rotary instrument, control. Differences between the microairborne-particle abrasion group and the remainder of the groups, desiccating agent--rubber-rotary instrument, desiccating agent-control, alcohol--rubber-rotary instrument, and alcohol-control groups, were statistically significant (P<.05). The microairborne-particle abrasion group displayed the roughest surface and a different surface topography from the remainder of the groups. Increased aluminum was observed in the microairborne-particle abrasion group. CONCLUSIONS Surface-cleaning techniques, except for the rubber-rotary instrument, increased the bond strength of composite resin. The roughest dentin surfaces and highest bond strength were achieved with the microairborne-particle abrasion technique.

Effect of different denture cleansers on surface roughness and microhardness of artificial denture teeth.

PURPOSE The aim of this study was to compare the effects of different denture cleansers on the surface roughness and microhardness of various types of posterior denture teeth. MATERIALS AND METHODS 168 artificial tooth specimens were divided into the following four subgroups (n=42): SR Orthotyp PE (polymethylmethacrylate); SR Orthosit PE (Isosit); SR Postaris DCL (double cross-linked); and SR Phonares II (nanohybrid composite). The specimens were further divided according to the type of the denture cleanser (Corega Tabs (sodium perborate), sodium hypochlorite (NaOCl), and distilled water (control) (n=14)) and immersed in the cleanser to simulate a 180-day immersion period, after which the surface roughness and microhardness were tested. The data were analyzed using the Kruskal–Wallis test, Conovers nonparametric multiple comparison test, and Spearmans rank correlation analysis (P<.05). RESULTS A comparison among the denture cleanser groups showed that NaOCl caused significantly higher roughness values on SR Orthotyp PE specimens when compared with the other artificial teeth (P<.001). Furthermore, Corega Tabs resulted in higher microhardness values in SR Orthotyp PE specimens than distilled water and NaOCl (P<.005). The microhardness values decreased significantly from distilled water, NaOCl, to Corega Tabs for SR Orthosit PE specimens (P<.001). SR Postaris DLC specimens showed increased microhardness when immersed in distilled water or NaOCl when compared with immersion in Corega Tabs (P<.003). No correlation was found between surface roughness and microhardness (r=0.104, P=.178). CONCLUSION NaOCl and Corega Tabs affected the surface roughness and microhardness of all artificial denture teeth except for the new generation nanohybrid composite teeth.

Beyazlatma sonrasında antioksidan uygulamasının minenin bağlanma kuvvetine etkisi

Amac: Bu calismanin amaci, % 10 sodyum askorbat (SA), %6.5 uzum cekirdegi ozu (UCO) ve % 10 alfa-tokoferol (α-TP)’ un farkli uygulama surelerinde, beyazlatilmis mineye, adeziv rezin simanin makaslama baglanma kuvvetini degerlendirmektir.Gerec ve Yontemler: 108 adet insan ust santral disi 9 gruba ayrilmistir (n:12). Kontrol grubu disindaki butun gruplara % 40’lik hidrojen peroksit (HP) kullanarak beyazlatma islemi uygulanmistir. Gruplar; GK: Beyazlatma uygulanmadan restorasyon yapilan (kontrol grubu), GB: Beyazlatma yapildiktan sonra restorasyon yapilan, GT7g: Yapay tukurukte 7 gun bekledikten sonra restorasyon yapilan, GSA15: 15 dakika sureyle % 10 SA uygulandiktan sonra restorasyon yapilan, GSA60: 60 dakika sureyle % 10 SA uygulandiktan sonra restorasyon yapilan, Gα-TP15: 15 dakika sureyle % 10 α-TP uygulandiktan sonra restorasyon yapilan, Gα-TP60: 60 dakika sureyle % 10 α-TP uygulandiktan sonra restorasyon yapilan, GUCO15: 15 dakika sureyle % 6.5 UCO uygulandiktan sonra restorasyon yapilan, GUCO60: 60 dakika sureyle %6.5 UCO uygulandiktan sonra restorasyon yapilan. Antioksidan uygulamasindan hemen sonra, indirekt restorasyonlar adeziv rezin simanla dis yuzeyine baglanmistir. Ornekler distile suda 24 saat 37°C’de bekletildikten sonra, makaslama baglanma kuvveti testi yapilmistir. Kirilma tipleri stereomikroskop altinda degerlendirilmistir. Veriler tek yonlu varyans analizi, Levene ve Tukey HSD testleri kullanilarak yapilmistir (α

Yıkama süresinin elastomerik ölçü materyallerinin ıslanabilirliği üzerine etkisi: in vitro çalışma

AMAC: Farkli yikama surelerinin polimerize olmus elastomerik olcu materyallerinin islanabilirlik degerleri uzerindeki etkisini degerlendirmektir. GEREC VE YONTEM: Panasil Contact Plus (PCP), Panasil Contact Surfaktansiz Deney Materyali (PCNS), Panasil Initial Contact (PIC), Express (EXP) ve Impregum (IMP) olcu materyalleri degerlendirildi. Olcu yuzeylerin islanabilirligi , 10 sn, 15 sn ve 20 sn surelerince su ile yikanan ornekler uzerinde temas acisi olcum cihazi kullanilarak olculdu (n=7). Olcum suresi 60 sn idi. Kontrol grubunda yikama yapilmadi. Olcumler 5 noktada yapildi (0, 6, 15, 30 ve 60. saniyeler). Kruskal Wallis testi ve tum olasi coklu karsilastirmalar icin Conover Coklu Karsilastirma testi kullanildi. Tip I hatayi kontrol etmek amaciyla Bonferroni duzeltmesi yapildi (p 0.002). SONUC: Yikama isleminin surfaktan iceren polivinilsiloksan olcu materyallerinin islanabilirliginin azalmasina neden oldugu, surfaktan icermeyen polivinilsiloksan olcu materyali ve polieter olcu materyalinde ise etkili olmadigi sonucuna ulasildi.

Surface detail reproduction under simulated pulpal pressure: A 3-dimensional optical profilometer and scanning electron microscopy evaluation

STATEMENT OF PROBLEM It is not clear whether more hydrophilic impression materials are better able to copy and transfer dentin surface detail than less hydrophilic ones. PURPOSE The purpose of this study was to evaluate the reproduction of dentin surface detail by means of hydrophobic and hydrophilic elastomeric impression materials under simulated pulpal pressure and their ability to transfer surface detail onto casts produced from such impressions. MATERIAL AND METHODS The wettability of the impression materials (n=8) was determined by contact angle measurement with an evolution period of 135 seconds. Dentin moisture was provided by means of pulpal pressure simulation, and objective analyses were performed by measuring the average roughness value (Ra) with a 3-D optical profilometer (n=10). One specimen from each group was analyzed with scanning electron microscopy. Contact-angle values were analyzed with a repeated measures ANOVA, and detail reproduction was tested with 3-way ANOVA (α=.05). The Bonferroni correction was used to control Type I error for follow-up analyses. RESULTS Contact angle measurements revealed significant differences depending on the impression material used and time of the measurement (P<.001). The Ra values of the hydrophilic impression materials, which were made from dry specimens, and the pulpal pressure simulated dentin surfaces did not differ from the dentin surfaces (P>.013). The hydrophobic impression material showed similar detail reproduction ability in a dry field, but loss of detail (evaluated subjectively) and increased roughness values (evaluated objectively) were recorded in a moisturized field (P=.004). Polyurethane-based cast material successfully reproduced the surface texture (P≥.006), whereas Type IV gypsum material was unable to reproduce this texture to the same extent. CONCLUSIONS The hydrophilic impression materials tested showed similar ability to reproduce detail under simulated pulpal pressure. Polyurethane-based cast material successfully reproduced the surface texture.