Ipek Caglar

The Effect of Sandblasting, Er:YAG Laser, and Heat Treatment on the Mechanical Properties of Different Zirconia Cores

OBJECTIVE The purpose of this study was to evaluate the effect of surface and heat treatments on the mechanical properties and phase transformation of yttria-stabilized tetragonal zirconia (Y-TZP) materials. BACKGROUND DATA Zirconia is exposed to several treatments during dental application process. Knowing the effect of applied treatments on zirconia is essential for clinical success. MATERIAL AND METHODS Forty disk specimens of Zirkonzahn (Z) and DC-Zirkon (DC) materials were fabricated. The specimens were randomly divided into four groups according to surface [control, sandblasting, Erbium: Yttrium Aluminum Garnet (Er:YAG) laser irradiation] and heat (firing) treatments. The surface roughness (Ra, μm) was measured using a surface profilometer. The relative amount of the transformed monoclinic (m) phase was analyzed by X-ray diffractometry (XRD). Biaxial flexural strength was tested using piston-on-three-ball technique. The data were analyzed with the Kruskal-Wallis H test with Bonferroni correction, and the Mann-Whitney U test was used for pairwise comparisons. RESULTS There were no significant differences in surface roughness among the treated groups (p > 0.05), whereas sandblasting showed higher surface roughness than other treatments for both materials. Scanning electron microscopic (SEM) analyses revealed changes in surface morphology after surface treatments, especially in laser groups with the formation of cracks, and in sandblasting groups with the formation of microretentive grooves. The greatest amount of the monoclinic phase was measured after sandblasting (8.13%) for Z and (19.8%) for DC. The monoclinic phase reverted to the tetragonal phase after heat treatment. Heat treatment groups showed significantly lower flexural strength than other treatments (p < 0.05). CONCLUSIONS Heat and surface treatments influenced the mechanical properties of zirconia ceramic. The biaxial flexural strength and crystalline phase of materials decreased after heat treatments.

The effect of various polishing systems on surface roughness and phase transformation of monolithic zirconia

PURPOSE The purpose of this study was to evaluate and compare three polishing systems on the surface roughness and phase transformation of monolithic zirconia. MATERIALS AND METHODS 100 disk shaped specimens (10 mm diameter, 3 mm thickness) were fabricated from monolithic zirconia blocks. 20 specimens were left as a control group and remaining specimens were grinded by diamond bur to simulate the occlusal adjustments. Grinded specimens were randomly divided into 4 groups: group G (no polishing), group M (Meisinger, zirconia polishing kit), group E (EVE Diacera, zirconia polishing kit), and group P (EVE Diapol, porcelain polishing kit). Surface roughness was measured with profilometer and surface topography was observed with SEM. XRD analysis was performed to investigate the phase transformation. Statistical analysis was performed with one-way ANOVA and Tukeys post hoc tests at a significance level of P=.05. RESULTS All polishing groups showed a smoother surface than group G. Among 3 polishing systems, group M and group E exhibited a smoother surface than the group P. However, no significant differences were observed between group M and group E (P>.05). Grinding and polishing did not cause phase transformations in zirconia specimens. CONCLUSION Zirconia polishing systems created a smoother surface on zirconia than the porcelain polishing system. Phase transformation did not occur during the polishing procedure.

The effect of different surface pretreatments on the bond strength of veneering resin to polyetheretherketone

Abstract The aim of this study was to investigate the effect of different surface pretreatment methods on the bond strength of veneering resin to polyetheretherketone (PEEK) based aesthetic frameworks. Five hundred and forty PEEK disks were fabricated and divided into 6 pretreatment groups (n = 90); (C) untreated control group, (B) airborne-particle abrasion, (S) silica coating, (L) etching with Er:YAG (erbium-doped yttrium aluminium garnet) laser, (LB) etching with Er:YAG laser and airborne-particle abrasion and (LS) etching with Er:YAG laser and silica coating. After topographical surface examinations, specimens were conditioned with adhesive and veneering resin was polymerized onto the PEEK specimens. Twenty-four hours after veneering, specimens were subjected to thermal aging. Afterwards, shear bond strength (SBS) tests were performed and the obtained data were analyzed with one-way ANOVA and Tukey test at a significance level of α = .05. Group B (1.58 ± 0.15 μm), Group L (1.79 ± 0.29 μm), Group LB (2.20 ± 0.23 μm) and Group LS (2.31 ± 0.52 μm) demonstrated significantly higher surface roughness (SR) values compared to Group C (1.03 ± 0.11 μm). Group B (10.97 ± 2.88 MPa), Group S (12.07 ± 2.82 MPa), Group LB (12.09 ± 2.08 MPa) and Group LS (13.14 ± 1.45 MPa) demonstrated significantly higher SBS values compared to Group C (6.35 ± 1.21 MPa). Airborne-particle abrasion, silica coating or their combined use with Er:YAG laser system establish durable bond between PEEK and resin; however, only Er:YAG laser treatment has no positive effect on resin-PEEK bond.

The effect of denture cleansers on surface roughness and bond strength of a denture base resin

Abstract Purpose: The purpose of this study was to evaluate the effect of different denture cleaning regimens on surface roughness of denture base material and bond strength to hard reline material. Materials and methods: 100 disk-shaped specimens were prepared from a denture base resin and immersed into the following five groups (n = 20): Group C: Corega Tabs, Group P: Protefix Tabs, Group CU: ultrasonic device with Corega Tabs and Group PU: ultrasonic device with Corega Tabs, and Control: distilled water. All cleaning protocols were applied for 90 times to each specimen according to the instructions of the manufacturers. Surface roughness values were measured using a profilometer and surface evaluations were performed with scanning electron microscope (SEM). Reline materials were applied on the specimens and shear tests were performed using a Universal Testing Machine. Data were analyzed using One-way ANOVA and Tukey’s post hoc tests were used for comparison among groups with a significance level of 0.05. Results: Group PU and group CU showed significant increase in surface roughness values compared to group P, C, and Control (p < 0.05). Control group showed significantly lower shear bond strength values compared to the other groups (p < 0.01). Group P exhibited higher shear bond strength values compared to group C (p = 0.003). No significant differences were found between group P and PU (p = 0.945), same results were found between group C and CU (p = 0.283). Conclusion: Using denture cleansers with ultrasonic devices significantly affected the surface topography of denture bases. All tested cleaning regimens increased the bond strength of hard reline material to the denture base.

Farklı mekanik yüzey işlemleri ile tamir edilen akrilik kaide rezininin transvers dayanımı

Amac: Bu calismanin amaci geleneksel isi ile polimerize olan akrilik rezinin tamirinde, tamir yuzeylerine uygulanan farkli mekanik yuzey islemlerinin akrilik rezinin transvers dayanimina etkisini arastirmaktir. Gerec ve Yontem : Ozel bir kalip yardimiyla dikdortgenler prizmasi seklinde 160 adet akrilik rezin ornek hazirlandi ve tamir yuzeylerine farkli islemler uygulamak uzere 4 farkli gruba ayrildi; Grup 1 islem uygulanmayan kontrol grubunu, Grup 2 kumlama uygulanan grubu, Grup 3 plazma uygulanan grubu ve Grup 4 Er:YAG lazer uygulanan grubu temsil etmektedir. Yuzey islemlerini takiben tamir yuzeyleri taramali elektron mikroskobu (SEM) ve enerji dagilimi spektroskopi (EDS) kullanilarak incelendi. Daha sonra ornekler otopolimerizan akrilik ile tamir edilerek yine dikdortgenler prizmasi seklinde (65×10×3.3 mm) toplam 80 adet ornek (n=20/grup) elde edildi. Tamir edilen orneklerin transvers dayanimi isisal dongu uygulandiktan sonra uc nokta bukme testi ile universal test cihazi kullanilarak olculdu. Sonuclarin istatistiksel analizi tek yonlu ANOVA ile yapildi ve sonrasinda Tukey HSD testi kullanilarak gruplara ait ortalamalar karsilastirildi. Sonuclar α =0.05 icin anlamli kabul edildi. Bulgular : Grup 2 (27.06 ± 5.02 MPa) ve Grup 4 (26.06 ± 3.44 MPa), kontrol grubuna (Grup 1; 18.26 ± 5.27 MPa) ve Grup 3’e (11.19 ± 2.73 MPa) gore istatistiksel olarak anlamli sekilde daha yuksek transvers dayaniklilik degerleri gosterdi (p<0.05), Grup 3 (11.19 ± 2.73 MPa) tum gruplardan istatistiksel olarak anlamli sekilde daha dusuk transvers dayaniklilik degerleri gosterdi (p<0.05). Sonuc : Geleneksel isi ile polimerize olan akrilik rezinin otopolimerizan akrilik rezin ile tamirinde, tamir yuzeylerine kumlama veya Er;YAG lazer uygulamasi akrilik rezinin transvers dayanimini arttirirken, plazma uygulamasi transvers dayanimi azaltti.