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Objective: To investigate the effect of sintering time on translucency and color of translucent zirconia ceramics.Materials and Methods: Sixty translucent zirconia (5Y-TZP) specimens (12 × 1.6 mm, Katana (KAT) and NexxZr (NEX)) were divided into six groups (n = 10) according to sintering time; 1, 2 (specified by manufacturer-control), and 3 hs. Color differences (ΔEab) within same material when sintered using different times and between materials when same sintering time was used were calculated, as well as translucency parameters (TP) after the use of each sintering time. Data for ΔEab and TP were analyzed with two-way ANOVAs, pairwise comparisons, and Fisher's LSD Test (Post-hoc).Results: When 1 or 3 h were used, color difference from the color of specimens when manufacturer-specified time (2 h) was used was similar for both KAT and NEX.ΔEab values of NEX were significantly higher than KAT when sintered for 1 or 3 h (P < 0.001). TP increased for KAT when sintered for 1 h, and was higher than NEX.TP for NEX increased when sintered for 3 h (P < 0.001), but was not significantly different than that of KAT.Conclusions: Effect of 1 or 3-h sintering on color was similar for both zirconias. For NEX, this effect resulted in greater differences from the color of specimens when manufacturer-specified time was used. Sintering for 1 h increased the translucency of KAT.

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This study aimed to investigate the effect of different cleansing solutions on the retention of precision attachments. A precision attachment patrix was embedded into acrylic resin and the matrix was placed onto the patrix. The red (high retention, 8 N), yellow (regular retention, 6 N), and green (reduced retention, 4 N) plastic matrixes of the attachments (n = 32) were soaked in three different denture cleansing solutions (sodium laureth sulfate, sodium bicarbonate-sodium perborate, sodium bicarbonate) for a duration simulating 6 months of clinical use. The control group was soaked in tap water. A universal testing machine was used to measure the retention values of attachments after they were soaked in denture cleansers. The retention values were compared among the groups with repeated-measures analysis of variance followed by the Tukey HSD test (p = 0.05). Yellow attachments were affected by sodium laureth sulfate, sodium bicarbonate-sodium perborate, and water (p = 0.012). Green attachments’ retention increased after immersion in sodium laureth sulfate (p = 0.04) and water (p = 0.02). Red attachments’ retention increased after immersion in sodium laureth sulfate or sodium bicarbonate-sodium perborate (p = 0.045). Water did not affect the retention of red attachments. Because sodium bicarbonate tablets did not affect the retention of attachments, clinicians may recommend their use as a cleanser. Clinicians also may inform patients using fixed and removable partial prostheses with precision attachments of a possible increase in retention after the use of sodium laureth sulfate or when using sodium bicarbonate-sodium perborate with yellow and red attachments.

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