Objective: The purpose of this study was to compare volumetric dimensional accuracy and stability of polyvinylsiloxane, polyether and new formulated polyvinylsiloxanether impression materials by using micro-computed tomography.Methods: A total of 42 impressions were made of stainless steel metal dyes. Polyvinylsiloxane, Polyether and Polyvinylsiloxanether impressions were taken for volumetric dimensional accuracy and stability to measure by Micro-computed tomography (μCT). Impression materials were measured for dimensional stability after the impression was taken, 24 hours later and 144 hours later. For dimensional accuracy 21 impressions and 21 stone models of these impressions were measured. One-way analysis of variance was be used to test for statistically significant difference within groups and Tukey’s test was be used to test for across groups with a significance value of p < 0.05.Results: After polymerization, although polyether impression negative was shown to have the highest volumetric expansion, the highest shrinkage was observed in the same group after pouring to dental stone. Stone model of the polyether was observed as the most accurate value of volume in comparison to the master model. The lowest volumetric dimensional change was observed in polyvinylsiloxanether at day 1 (-0.004±0.001%) and the highest change was observed in polyether at day 7 (-0.052±0.004%).Conclusion: From the standpoint of volumetric accuracy and stability, all three elastomeric impressions are acceptable and μCT is a useful tool for assesments of volumetric dimensional changes.

Objective: With the widespread use of CAD/CAM (computer aided design and manufacture) systems in dentistry, many restorative materials have been produced. In our study, we aimed to evaluate the change in optical properties of newly developed translucent monolithic zirconia (TMZ) (Cercon HT Dentsply, Sirona, USA), zirconia-reinforced lithium silicate (ZLS) (Celtra Duo, Dentsply, Germany) and lithium disilicate (LS2) (IPS e.max CAD, Ivoclar Vivadent, Liechtenstein) materials with aging. Methods:10 discs of 12mm diameter and 1.2 mm thickness were produced from high translucent A2 color of each material. The aging process was applied in an autoclave under 134ºC, 0.2MPa pressure. For optical evaluation, L*, a*, b* values of the samples were measured by spectrophotometry before aging, after 3 hours and 6 hours aging. ΔE00 values and translucency parameters (TP) were calculated. The data were evaluated statistically. Results: In the present study, all the materials had undergone color change as a result of aging, but this change was within acceptable limits (ΔE00 0.8). There was a decrease in the translucency of all materials used in the study, but this decrease was not statistically significant. Conclusion: In the light of the findings obtained from this in vitro study, aging did not cause color and translucency changes in TMZ, ZLS, LS2 monolithic CAD/CAM materials.

Objective: To evaluate the shear bond strength (SBS) of yttrium-stabilized tetragonal zirconia polycrystals bonded to titanium alloys via different surface treatment methods using four different cements. Methods: Eighty titanium and monolithic zirconia discs were prepared with computer-aided design/manufacturing (CAD/CAM) technology. All titanium discs and 40 of monolithic zirconia discs were polished by using silicon carbide paper and sandblasted with 50 μm aluminum oxide (Al2O3). Tribochemical silica coating was applied to remaining 40 monolithic zirconia discs. The monolithic zirconia discs were divided into eight groups after surface treatment (n=10). Titanium discs were cemented using conventional glass ionomer cement (GIC), resin-modified GIC, self- adhesive resin cement, and dual-cure resin cement. The SBS test was performed using a universal testing machine. The failure patterns were examined by using a scanning electron microscope (SEM). Data were statistically analyzed with one-way analysis of variance (ANOVA), two-way ANOVA and Tukey’s test (α<.05). Results: The SBS values differed according to the surface treatment methods and cements used (p<.001). The highest and lowest SBS values were measured in the tribochemical-silica-coated G-CEM ONE (34.77±5.53 MPa) and Al2O3 sandblasted GC Fuji I (3.30±0.77 MPa) cement groups, respectively. Failure analysis revealed that 41.25%, 31.75% and 25% of the failures were cohesive, adhesive, and combined failures, respectively. Conclusion: The SBS values between the monolithic zirconia and titanium alloy were significantly higher in the resin cement groups containing 10-methacryloyloxydecyl dihydrogen thiophosphate and 10 methacryloyloxydecyl dihydrogen phosphate (p<.05). While adhesive and combined failures were observed at high SBS values, cohesive failures were detected as the bonding values decreased.

CAD/CAM, computer aided design ve computer aimed manufacturing kelimelerin baş harfleri ile elde edilmiş kısaltmadır. Türkçesi, bilgisayar destekli dizayn ve bilgisayar destekli üretim anlamına gelmektedir. CAD/CAM sağlık sektöründe, fizyoterapi ve ortez-protez alanında protez soketi ve ortezleme ölçü alımı ve üretiminde, ayak basınç analizine bağlı bireysel tabanlık uygulamalarında ve diş hekimliğinde çeşitli alanlarda kullanılmaktadır. Diş hekimliğinde CAD/CAM ilk defa 1970’li yıllarda kullanılmıştır. Diş hekimliğinde CAD/CAM dijital ortodonti, cerrahi kılavuz ve modellerde, dental implantlarda ve protetik diş tedavilerinde kullanılmaktadır. CAD/CAM ile protetik restorasyonların üretilmesi alternatif bir yaklaşım sunmaktadır. CAD/CAM geleneksel yöntemler ile kıyaslandığında mum modelaj, döküm gibi hataya yol açabilen basamakları atlayabilme avantajına sahiptir. CAD/CAM sistemlerinin gelişmesi ile estetik ve fonksiyonel beklentiler de artmıştır. Bu beklentileri karşılamak için yeni materyaller geliştirilmiştir. Üretimde kullanılan materyaller özetle şu şekilde sınıflandırılmaktadır; kompozitler, metaller, polimerler, polimetilmetakrilatlar ve seramiklerdir.

Objective: Novel strength-gradient monolithic zirconia is a developed material recently introduced to the market and its mechanical properties should be investigated in vitro. The aim of the study is to compare the wear rates of three different CAD/CAM materials with a chewing simulator after one year of dynamic loading. Methods: 7x7x3 mm discs were prepared from lithium disilicate, strength-gradient monolithic zirconia, and zirconia-reinforced lithium silicate glass ceramic. Both groups were divided into two subgroups (n=12) as glazed and mechanically polished. The samples were scanned with a laser scanner device (SD Mechatronic Laser Scanner LAS-20, Westerham, Germany) to determine the amount of wear. The samples were placed in a chewing simulator (SD Mechatronic Chewing Simulator CS-4.2, Westerham, Germany) for 240 000 cycles which is equivalent to 1 year of clinical use. After the dynamic loading in the chewing simulator, the samples were scanned again in the laser scanner, and the data was obtained. Kruskal Wallis test was used to analyze the data. Results: The amount of wear of each material was found to be statistically significant (p< .05). No significant differences between the polished and glazed groups of Zir and LD were found but glazed CD was significantly more wear-resistant than polished CD (p< .05). Conclusions: Wear is a phenomenon that can be affected by different factors such as microstructure and surface finishing of the materials. Wear resistance should be taken into consideration when choosing a material.