Omer Sagsoz

Background: This study aimed to investigate the biomechanical behavior of conservative inlay restorations fabricated from different CAD/CAM materials by combining experimental flexural strength testing with finite element analysis. Methods: Five CAD/CAM materials were evaluated: feldspathic ceramic (Cerec Blocs), leucite-reinforced ceramic (IPS Empress CAD), resin nano-ceramic (Lava Ultimate), polymer-infiltrated ceramic network (VITA Enamic), and lithium disilicate ceramic (IPS e.max CAD). Young’s modulus and Poisson’s ratio were experimentally determined using three-point bending and nanoindentation tests and used as inputs for 3D FEA. Von Mises (VM) stress distributions within the inlays were analyzed under simulated occlusal loading. Results: Maximum VM stresses showed an inverse relationship with material elasticity. IPS e.max CAD exhibited the highest maximum VM stress (45.571 MPa), whereas the resin nano-ceramic showed the lowest (25.419 MPa). Despite higher stress concentrations in high-modulus ceramics, VM values for all materials remained well below their FS limits. Conclusions: All materials demonstrated adequate mechanical stability under physiological loading. Lithium disilicate showed a comparatively larger margin between stress levels and flexural strength, while lower-modulus materials tended to promote greater stress transfer to supporting structures.

This study aims to evaluate the effects of different surface treatments and adhesive systems on the shear bond strength (SBS) of additively manufactured (AM) and subtractively manufactured (SM) restorative materials. A total 675 rectangular specimens of three AM (Saremco Crowntec/SC, VarseoSmile CrownPlus/VC, and VarseoSmile TriniQ/VT) and two SM (Vita Enamic/VE and Cerasmart/CS) restorative materials were fabricated. Each material was randomly divided into three groups regarding surface treatments: control/C, sandblasting/S, and etching/E. Following surface treatments, each AM and SM restorative material was then divided into three subgroups (15 specimens/subgroup) on the basis of adhesive systems (etch-and-rinse, self-etch, and universal). All specimens were thermocycled at 10,000 cycles, 5–55 °C, 30 s dwell time, and tested under SBS until failure, and failure types were examined under a stereomicroscope. Representative specimens were examined by SEM to evaluate fracture morphology. Statistical analysis was set at p < 0.05. There were significant differences in bond strength according to the material, surface treatment, adhesives, and their interactions (p < 0.05). The highest SBS value was obtained with SC × sandblasting × etch-and-rinse (16.45 ± 0.93 MPa), while the lowest value was found in the CS × control × universal interaction (4.68 ± 1.1 MPa). Outcomes varied according to the materials, surface treatment, and adhesive strategy. Clinically, these findings indicate that SM materials may require various surface treatment to achieve reliable adhesion, whereas AM materials provide more similar bond strength performance with no surface treatment.

Denture hygiene is crucial for preventing oral infections, with Candida albicans being a common fungal pathogen that can colonize denture surfaces. This in vitro study evaluated the adherence of C. albicans on two denture base materials—polyamide and polymethyl methacrylate (PMMA)—and assessed the antifungal efficacy of various chemical and natural cleansers. A total of 100 polished specimens were inoculated with C. albicans and treated with chemical agents (Listerine at 2%, 20%, 50%; Corega^®, Block Drug Company, Jersey City, NJ, USA); Protefix^®, Queisser Pharma, Flensburg, Germany and natural products (15% apple vinegar, 2% tea tree oil, 2% peppermint oil) for different durations (5, 15, 30, 480 min). Chlorhexidine (2%) and untreated samples served as positive and negative controls, respectively. Corega^® and 15% vinegar eliminated C. albicans within 5 min on both materials. 50% Listerine was effective after 5 min on PMMA but required 480 min on polyamide. Protefix^® showed full efficacy in 5 min on PMMA and 30 min on polyamide. Tea tree oil required 30–480 min for activity, while peppermint oil showed minimal effect throughout. Under the tested conditions, Corega^® appeared most effective. Natural cleansers, particularly vinegar and tea tree oil, also showed considerable anticandidal potential, suggesting they may serve as alternative agents for denture hygiene applications.

The aim of this study is to evaluate the color stability, translucency and hardness of eight different composite resins, after thermal cycling and immersion in beverages. Six light-cured dimethacrylate-based composite (Clearfil Majesty Esthetic, Clearfil Majesty Posterior, Grandio, Grandio Flow, Arabesk Top, Valux Plus), an ormocer (Admira) and a silorane-based composite (Filtek Silorane) were tested in this study. Fifteen samples (8x2 mm) from each composite were prepared. All samples were subjected to thermal cycling [(5.0 ± 0.5)~(55.0 ± 1.0) °C, 1000 cycles]. After thermal cycling, fifteen specimens in each group were divided into three subgroups (n = 5): distilled water (control), coffee, and red wine at 37°C for 30 days. With a spectrophotometer, the △E and Translucency Parameter (TP) were calculated against white and black backgrounds. Color, translucency and hardness of all samples were remeasured baseline, after thermal cycles and after immersion in beverages. The data were analyzed using repeated measured analysis of variance and Bonferroni multiple-comparison test (P 3.3). The effect of thermal cycles on color and transluceny was not statistically significant (P>0.05). TP values generally decreased especially after immersion in red wine (P<0.05). Hardness values were varied among composite resins but generally decreased after thermal cycles and immersion especially in red wine. Thermal cycling and immersion in beverages caused to decrease in hardness values for composite materials. Because of negative effects on color and translucency, it should be noted especially red wine consumption.

BACKGROUND: The chemical properties of the oral environment have an appreciable influence on the in vivo degradation of CAD/CAM materials. OBJECTIVE: The aim of the present study was to investigate the effect of organic acids, heptane and ethanol (th

The purpose of this study was to evaluate the bond strength between CAD/CAM materials and a resin cement using hydroxyapatite coating as a surface treatment method. Different surface treatments (Control, no treatment-C; Sandblasting-SB; Hydrofluoric acid etching-HF; applying tooth desensitizer-TeM; applying topical crème-ToM, HAp coating with Pulse Laser Deposition technique-PLD) were applied to three different CAD/CAM materials (LAVA Ultimate, VITA Enamic, and Cerec Blocs). After surface treatments, a universal adhesive (Single Bond Universal, 3M ESPE) was applied and adhesive resin (Rely X Ultimate, 3M ESPE) were cemented on each material surface using plastic tubes (4 mm in diameter). The shear bond strength values were measured using a universal testing machine. Scanning electron microscope analysis were performed to evaluate failure modes and effects of surface treatments. Obtained data were statistically analyzed using two-way ANOVA and Tukey’s post hoc test (p = 0.05). The bond strength of PLD groups were significantly higher than other groups in resin-ceramics (p < 0.05). In Cerec Blocs, HF resulted significantly higher bond strength than other groups (p < 0.05). SEM analysis of surface treatment methods (except TeM and ToM) revealed an increase in surface alterations compared to control groups. Failure modes were dominantly adhesive in groups C, TeM, and ToM, whereas mostly mix or cohesive failures were observed in PLD, HF, and SB. Hydroxyapatite coating with PLD technique exhibited promising bond strength results for CAD/CAM resin-ceramics. HAp coating can be used as a replacement for hydrofluoric acid etching and sandblasting in CAD/CAM resin-ceramic materials to obtain better bond strength values.

Dspathic ceramic, CEREC blocs; leucite-reinforced ceramic, IPS Empress CAD; resin nano ceramic, 3M ESPE Lava Ultimate; hybrid ceramic, VITA Enamic; and lithium disilicate ceramic, IPS e.max CAD) using CEREC 4 CAD/CAM system. Samples were adhesively cemented to metal analogs with a resin cement (3M ESPE, U200). The fracture tests were carried out with a universal testing machine. Furthermore, five samples were prepared from each CAD/CAM material for micro-Vickers hardness test. Data were analyzed with statistics software SPSS 20 (IBM Corp., New York, USA). Results: Fracture strength of lithium disilicate inlays (3949 N) was found to be higher than other ceramic inlays (P < 0.05). There was no difference between other inlays statistically (P > 0.05). The highest micro-Vickers hardness was measured in lithium disilicate samples, and the lowest was in resin nano ceramic samples. Conclusion: Fracture strength results demonstrate that inlays can withstand the forces in the mouth. Statistical results showed that fracture strength and micro-Vickers hardness of feldspathic ceramic, leucite-reinforced ceramic, and lithium disilicate ceramic materials had a positive correlation....

FRACTURE STRENGTH EVALUATION OF CAD/CAM LAMINATE VENEERS PREPARED WITH DIFFERENT METHODS AND DIFFERENT CEMENT THICKNESSES Amaç: Bu çalışmanın amacı; 2 farklı siman aralığında ve 2 farklı preparasyon tekniği ile CAD/CAM kullanılarak hazırlanan laminate veneerlerin kırılma direncini karşılaştırmaktadır. Gereç ve Yöntem: Çalışmada 40 adet benzer boyut- larda seçilen üst anterior diş kullanıldı. Her dişe lamina- te preparasyonu yapıldıktan sonra laminate veneer ile restore edildi. Dişler, preparasyon teknikleri; insizalde sonlanan geleneksel kesim ve insizali içine alan kesim ile siman aralıkları; 50 µm ve 200 µm olacak şekilde 4 gruba ayrıldı. Laminateler feldspatik seramik bloklar kullanılarak Cerec CAD/CAM cihazı yardımıyla hazırlanıp self etch rezin siman ile uygulandı. 125 derecelik açıyla kendinden sertleşen akril silindirik bloklara gömülen dişlere üniversal test cihazıyla (Instron 3344) sabit hızda kuvvet uygulanarak kırma testi gerçekleştirildi. Laminatelerin kırılma kuvvetleri kaydedildi. Elde edilen sonuçlar SPSS 20 istatistik yazılımı kullanılarak tek yönlü varyans analizi ve Tukey post hoc testi kullanılarak istatiksel olarak değerlendirildi. Bulgular: Siman aralığı karşılaştırıldığında 50 µm, 200 µm siman aralığına göre daha yüksek kırılma direnci gösterdi. Kesim teknikleri karşılaştırıldığında geleneksel kesim insizale overlap kesime göre daha yüksek kırılma direnci gösterdi. En yüksek ortalama kırılma direnci geleneksel kesim ve 50 µm siman aralığında (643 N), en düşük değer insizale overlap kesim ve 200 µm siman aralığında (359.8 N) kaydedildi. Sonuç: Geleneksek kesim tekniği laminate veneerlerin kırılma direncini arttırır. Siman aralığı azaldıkça kırılma direnci artar. Anahtar keli meler: Kesim tekniği, kırılma direnci, laminate veneer, siman aralığı ABSTRACT Aim: The aim of this investigation is to evaluate fracture resistance of veneer materials which prepared in two different methods with two different cement thicknesses by CAD/CAM. Material and Method: Forty maxillary incisors in similar sizes were used in this study. Each tooth restored with laminate after preparation. Teeth were divided into 4 groups according to preparation techniques; traditional preparation and incisal-overlap preparation, and cement thicknesses; 50 µm and 200 µm . Laminates were milled with Cerec CAD/CAM device (Sirona) from feldspathic ceramic blocks and applied using self etch resin cement. Fracture tests were performed applying load with constant speed using a universal testing machine (Instron 3344) to teeth embedded into cylindrical self-cure acrylic resin blocks with 125-degree angle. Fracture load values of laminates were recorded. Results were evaluated statistically with one-way ANOVA and Tukey post hoc tests using SPSS 20 software. Results: In terms of cement thickness, 50 µm showed statistically higher fracture strength values than 200 µm. In terms of preparation technique, traditional technique showed higher fracture strength than incisal-overlap technique. The highest mean fracture strength was recorded for traditional preparation with 50 µm (643 N), while the lowest was for incisal-overlap preparation with 200 µm (359.8 N). Conclusion: Traditional preparation technique increa- ses fracture strength of laminate veneers. Fracture strength increases as cement thickness reduced. Keywords: Preparation technique, fracture resistance, laminate veneer, cement thickness * Atatürk Üniversitesi, Diş Hekimliği Fakültesi, Restoratif Diş Tedavisi Anabilim Dalı

Sagsoz O, et al. J Adv Prosthodont. 2016 Dec;8(6):417-422. https://doi.org/10.4047/jap.2016.8.6.417