METHODS: Six master dies were duplicated from the prepared maxillary first premolar tooth using nonprecious metal alloy (Wiron 99). Thirty copings (Procera AllCeram) of 0.6-mm thickness were manufactured. Three types of luting media were used: zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and dual-cured composite resin cement (Panavia F). Ten copings were cemented with each type. Two master dies were used for each group, and each of them was used to lute five copings. All groups were cemented according to manufacturer's instructions and received a static load of 5 kg during cementation. After 24 hours of distilled water storage at 37 degrees C, the copings were vertically compressed using a universal testing machine at a crosshead speed of 1 mm/min.

RESULTS: ANOVA revealed significant differences in the load at fracture among the three groups (p < 0.001). The fracture strength results showed that the mean fracture strength of zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and resin luting cement (Panavia F) were 1091.9 N, 784.8 N, and 1953.5 N, respectively.

Objectives: The aim of this study was to assess the relationship between khat and occlusal caries progression.

Methods: A cohort study was carried out among 98 Yemeni khat chewers and 101 non-chewers aged 18-35 years old with early occlusal caries lesions. All participants answered questions on socio-demographic, khat , oral hygiene , sugar intake, and oral health knowledge at baseline. All posterior teeth with an early enamel lesion on occlusal surfaces detected by visual inspection at baseline were also subjected to DIAGNOdent assessment to confirm early lesion (DIAGNOdent reading 13-24). Participants were re-examined after 12 weeks. Caries progression was considered to occur when the DIAGNOdent reading was >25. Data were analyzed using Relative risk, Mann-Whitney U test, a Wilcoxon Signed-Rank test and logistic regression analysis.

Results: Occlusal caries progression incidence between khat chewers and non-chewers, with the relative risk was 1.68. There was no significant difference in occlusal caries progression on chewing side and non-chewing side among khat chewers. Khat chewing was a statistical predictor for those with low income.

AIM: To evaluate the shear bond strength of Zinc phosphate cement Elite, glass ionomer cement Fuji I, resin-modified glass ionomer cement Fuji Plus and resin luting cement Panavia-F to Turkom-Cera all-ceramic material.

MATERIALS AND METHODS: Turkom-Cera was used to form discs 10mm in diameter and 3 mm in thickness (n = 40). The ceramic discs were wet ground, air - particle abraded with 50 - μm aluminium oxide particles and randomly divided into four groups (n = 10). The luting cement was bonded to Turkom-Cera discs as per manufacturer instructions. The shear bond strengths were determined using the universal testing machine at a crosshead speed of 0.5 mm/min. The data were analysed using the tests One Way ANOVA, the nonparametric Kruskal - Wallis test and Mann - Whitney Post hoc test.

RESULTS: The shear bond strength of the Elite, Fuji I, Fuji Plus and Panavia F groups were: 0.92 ± 0.42, 2.04 ± 0.78, 4.37 ± 1.18, and 16.42 ± 3.38 MPa, respectively. There was the statistically significant difference between the four luting cement tested (p < 0.05).