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Objectives: To evaluate the relative translucency parameter (RTP) values of computer-aided design (CAD)-computer-aided manufacturing (CAM) materials after UV aging.Materials and methods: 70 specimens (n = 10) of Bruxzir Anterior (BA); E.max Cad (EC); Lava Ultimate (LU); Cerasmart (CE); Vita Enamic (VE); Vita Suprinity (VS); Vita Mark II (VM) were prepared (1 mm ± 0.01 mm). Color measurements were performed using a spectrofotometer (VITA Easyshade). RTP values of the specimens before (RTP 1 ) and after UV aging (RTP 2 ) were evaluated. Statistical analyses were done with repeated measurements of two-way-ANOVA with Bonferroni test (P < 0.05).Results: Evaluating RTP 1 and RTP 2 values; significant differences were found (P < 0.05). There were no significant difference between the RTP 1 values of CE and VS (P = 0.779); EC and VM (P = 0.952); VM and LU (P = 0.995); EP and LU (P = 0.653). Evaluating RTP 2 values; VE and BA were found significantly different from the others (P < 0.05). For all evaluated groups TP values decreased after UV aging (P < 0.05). The most RTP reduction was observed for LU; while VM and EC were less affected.Conclusion: Glass ceramic VE showed the highest RTP and zirconia-based BA was the most opaque restorative CAD-CAM material. UV aging caused the CAD-CAM materials get more opaque.Clinical significance: In cases where translucency is needed chosing VE would give better esthetic results; while zirconia-based BA should be used if more opaque restoration is needed.Clinicians should be aware of that restorations get more opaque after usage. K E Y W O R D S

PURPOSE To assess shear bond strengths (SBS) of resin composites on aged and non-aged prosthetic materials with various surface treatments. MATERIALS AND METHODS Cerasmart (CE), Vita Enamic (VE), Vita Mark II (VM), and IPS e.max CAD (EC) blocks were sliced, and rectangular-shaped specimens (14 × 12 × 1.5 mm; N = 352) were obtained. Half of the specimens were aged (5000 thermal cycles) for each material. Non-aged and aged specimens were divided into 4 groups according to the surface treatments (control, air abrasion, etching, and laser irradiation; n = 11) and processed for scanning electron microscopy (SEM). The repair procedure was performed after the surface treatments. SBS values and failure types were determined. Obtained data were statistically analyzed ( P ≤.05). RESULTS The material type, surface treatment type, and their interactions were found significant with regard to SBS ( P <.001). Aging also had a significant effect on prosthetic material-resin composite bonding ( P <.001). SBS values of non-aged specimens ranged from 12.16 to 17.91 MPa, while SBS values of aged specimens ranged from 9.46 to 15.61 MPa. Non-aged VM in combination with acid etching presented the highest score while the control group of aged CE showed the lowest. CONCLUSION Etching was more effective in achieving durable SBS for VM and EC. Laser irradiation could be considered as an alternative surface treatment method to air abrasion for all tested materials. Aging had significant effect on SBS values generated between tested materials and resin composite.

ObjectiveThe objective of the present research was to evaluate the effect of sintering temperatures (1350°C, 1450°C, and 1600°C) of a novel multi‐layered esthetic zirconia material (Katana 12Z/STML) on the grain sizes and on the translucency parameters (TP00) for 2 different shades (A2‐A3) and 2 different thicknesses (1‐1.5 mm).Material and MethodsA total of 120 non‐sintered specimens were randomly divided into three subgroups according to sintering temperatures. The TP00 and grain sizes of the sintered specimens were calculated. Statistical analyses were performed using 3‐way ANOVA, 1‐way ANOVA, and Tukey's post hoc tests.ResultsTP00 increased 1.2 to 1.5 times as the specimen thickness decreased from 1.5 to 1 mm (P ≤ .05). The lowest TP00 values were recorded for sintering at 1350°C for the investigated thicknesses and shades (P ≤ .05). The interaction of sintering temperature and shade was significant (P ≤ .05). Grain sizes were ordered according to sintering temperature as 1350°C < 1450°C < 1600°C (P ≤ .05).ConclusionsTP00 values decreased with the increase in the thickness of the monolithic zirconia. The sintering temperatures and their interaction with shade significantly affected TP00 values. The grain size increased with increasing sintering temperature.Clinical significanceThe translucency of a novel multi‐layered monolithic zirconia increased with higher sintering temperatures and lower thickness. The grain size increased with the increase in the sintering temperature. The sintering temperature of 1600°C led to a significant change in translucency for shade A3.

Objective. To evaluate the effect of different desensitizing toothpastes and coffee staining on the discoloration rate of natural human tooth and composite materials. Materials and Methods. A total of 56 human teeth and 56 composite specimens were used. After initial color measurements were taken, specimens and teeth were exposed to simulated toothbrushing with six desensitizing toothpastes containing different active ingredients: stannous fluoride, strontium acetate, potassium citrate and hydroxyapatite, cetylpyridinium chloride, arginine, and novamin. Specimens were then exposed to coffee staining. Throughout the staining procedure, the storing solution was refreshed every day and the specimens were brushed with the tested toothpastes. Color measurements and changes were recorded at each stage and analyzed with one-way ANOVA, Dunnett tests, and paired sample t-test (p<0.05). Results. The largest color change was obtained with the stannous fluoride toothpaste after coffee staining for natural teeth (2.6 ΔE00⁎) and composite specimens (3.1 ΔE00⁎). Coffee staining resulted in significant changes for ΔE00⁎ values of all groups, except for natural teeth brushed with a novamin-based (p= 0.06) toothpaste. For composite specimens, only the stannous fluoride and cetylpyridinium chloride-based toothpastes resulted in significant color changes relative to the control group. ΔL⁎ and Δb⁎ values were also increased after staining for all groups (p<0.05). Conclusions. Desensitizing toothpastes alone did not cause perceptible color changes; however, in combination with coffee staining, it tended to increased discoloration for both composites and natural teeth.