Sabit Melih Ates

Influence of Tooth Preparation Design on Fitting Accuracy of CAD‐CAM Based Restorations

OBJECTIVE The purpose of this study was to evaluate the marginal fit of different zirconia and metal frameworks and compare them with each other on different finish line configurations. MATERIALS AND METHODS 20 stainless steel dies 10 with shoulder and 10 with chamfer finish line including 6 mm preparation height and 3 degree axial angle simulating a 6 degree total occlusal covergence of the prepared tooth were produced. After embedding the each group of die into the arch-shaped acrylic resin blocks, impressions were made using silicone based impression material and 120 casts were prepared subsequently. The dies were divided into six groups each having 20 specimens (10 with shoulder, 10 with chamfer finish line). Group CM consisted of Co-Cr produced by conventional casting procedure, group MM of Co-Cr prepared by metal milling, group LM of Co-Cr prepared by direct laser metal sinterization (DLMS), group ZZ of Zirkonzahn (Zirkonzahn GmbH, Gais, Italy), group LZ of Lava Zirconia (3 M ESPE Dental AG, Seefeld, Germany) and group DZ of DC-Zirkon (DCS Dental AG, Allschwil, Switzerland). Stereomicroscope were used to evaluate the marginal fit of frameworks and marginal gap values obtained from the images were analyzed using Mann-Whitney U Test and Kruskal-Wallis H Test with Bonferroni correction. RESULTS The lowest value of marginal gap was identified in the samples from the LZ group and the highest value was identified in those from ZZ in both finish lines. The effect of finish lines was not significant for most groups but CM frameworks with chamfer finish lines and the DZ frameworks with shoulder finish lines showed significantly lower marginal gap values. CONCLUSION The marginal gaps of the various tested zirconia and metal framework were within the range of clinical acceptability (120 µm). CLINICAL SIGNIFICANCE The results of this in vitro study suggest that margin preparation design and type of zirconia and metal framework materials for various CAD-CAM systems have a significant effect on marginal fit of the resulting restorations. (J Esthet Restor Dent 28:238-246, 2016).

Peel strength of denture liner to PMMA and polyamide: laser versus air-abrasion

PURPOSE This study investigated the effect of laser parameters and air-abrasion on the peel strength of silicon-based soft denture liner to different denture resins. MATERIALS AND METHODS Specimens (N=180) were prepared out of three different denture base resins (Rodex, cross-linked denture base acrylic resin; Paladent, heat-cured acrylic resin; Deflex, Polyamide resin) (75 mm × 25 mm × 3 mm). A silicon-based soft denture liner (Molloplast B) was applied to the denture resins after the following conditioning methods: a) Air-abrasion (50 µm), b) Er,Cr:YSGG laser (Waterlase MD Turbo, Biolase Technology) at 2 W-20 Hz, c) Er,Cr:YSGG laser at 2 W-30 Hz, d) Er,Cr:YSGG laser at 3 W-20 Hz, e) Er,Cr:YSGG laser at 3 W-30 Hz. Non-conditioned group acted as the control group. Peel test was performed in a universal testing machine. Failure modes were evaluated visually. Data were analyzed using two-way ANOVA and Tukeys test (α=.05). RESULTS Denture liner tested showed increased peel strength after laser treatment with different parameters (3.9±0.4 - 5.58±0.6 MPa) compared to the control (3.64±0.5 - 4.58±0.5 MPa) and air-abraded groups (3.1±0.6 - 4.46±0.3 MPa), but the results were not statistically significant except for Paladent, with the pretreatment of Er,Cr:YSGG laser at 3 W-20 Hz. Polyamide resin after air-abrasion showed significantly lower peel strength than those of other groups (3.1±0.6 MPa). CONCLUSION Heat-cured acrylic resin, PMMA, may benefit from Er,Cr:YSGG laser treatment at 3 W-20 Hz irradiation. Air-abrasion of polyamide resins should be avoided not to impair their peel bond strengths to silicon-based soft denture liners.

Evaluation of the bond strength of different adhesive agents to a resin-modified calcium silicate material (TheraCal LC).

This study evaluated the bond strength of different adhesive agents to TheraCal LC and mineral trioxide aggregate (MTA) and examined the morphologic changes of these materials with different surface treatments. A total of 120 specimens, 60 of MTA Angelus (AMTA), and 60 of TheraCal LC, were prepared and divided into six subgroups according to the adhesive agent used; these agents included Scotchbond Multipurpose, Clearfil SE Bond, Clearfil Protect Bond, Clearfil S3 Bond, OptiBond All-in-One, and G-aenial Bond. After application of adhesive agents, Filtek Z250 composite resin was placed onto the specimens. Shear bond strengths were measured using a universal testing machine, followed by examination of the fractured surfaces. The surface changes of the specimens were observed using scanning electron microscopy. Data were compared by two-way analysis of variance. Although no significant differences were found among the bond strengths of different adhesives to AMTA (p = 0.69), a significant difference was found in terms of bond strengths of different adhesives to the TheraCal LC surface (p < 0.001). The total-etch adhesive system more strongly bonded to TheraCal LC compared to the bond with other adhesives. TheraCal LC bonded significantly more strongly than AMTA regardless of the adhesive agents tested. Resin-modified calcium silicate showed higher bond strength than AMTA in terms of the composite bond to these materials with different bonding systems. On the other hand, the highest shear bond-strength values were found for composite bonds with the combination of TheraCal LC and the total-etch adhesive system. SCANNING 38:403-411, 2016.

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.