Color Stability of Monolithic Zirconia in Various Staining Liquids: An In Vitro Study

This study aimed to compare the color stability of monolithic zirconia (MLZ) after immersion in various staining liquids. Fifty MLZ samples (n = 50) were color infiltrated by brushing/painting the samples pre-sintering. All zirconia samples were then brushed inside a toothbrushing simulator machine to create abrasion. Ten samples each were immersed in artificial saliva (gp-1), coffee (gp-2), protein shake (gp-3), chlorhexidine mouthwash (gp-4), and a soft drink (gp-5). Besides chlorhexidine mouthwash (immersion time: 14 days), the samples were immersed in the liquids for 28 days. A spectrophotometer was utilized to observe the color differences (∆E) at the baseline vs. 28 days post-immersion. The means and standard deviations were compared using analysis of variance (ANOVA) and a multiple comparisons test. A p-value p p p > 0.05). The results of the present study demonstrate that coffee immersion of MLZ samples causes more significant discoloration (increased ∆E values) than other liquids. Further in vitro and clinical studies are warranted to corroborate the present study’s findings

Push-Out Bond Strength of Endodontic Posts Cemented to Extracted Teeth: An In-Vitro Evaluation

(1) Background: An ideal bond strength between endodontic posts and root canal dentin is essential for optimal retention and good prognosis. This study aimed to evaluate the push-out bond strength (PBS) of prefabricated fiber and metal posts, luted with resin cement to natural dentin. (2) Methods: Extracted premolars with similar root dimensions were assigned into two groups of 30 each for the metal and fiber posts. Teeth were mounted in acrylic blocks exposing 2 mm of the coronal root. Teeth were subjected to endodontic treatment and post-space preparations. Two groups were further subdivided into three sub-groups (n = 10) according to the size of the posts (# 4, 5 and 6). Posts were cemented with resin cement. Specimens were sectioned into 4 mm slices and subjected to the PBS test. (3) Results: The mean PBS was similar for the metal and fiber posts bonded with resin cement, showing a statistically significant result. An increase in post size increased the bond strength initially, but a further increase in size did not show any marked difference. A total of 71.66% of tested specimens failed with the adhesive failure mode. (4) Conclusions: Metal posts showed slightly higher retention compared to the fiber posts, although the p-value was similar for both types. An increase in the size of posts showed increased retention. The most common mode of failure was adhesive failure between cement and dentin