two groups of patients will be selected according to special inclusion criteria n=13 in each group total of 26. each group will receive one of the crowns used in this study either ( monolithic zirconia or zirconia reinforced lithium silicate glass) after crown delivery wear and patient satisfaction will be recorded at 0,3,6,12 moths follow-up periods.
evaluation of wear behavior and patient satisfaction of monolithic zirconia and zirconia reinforced glass crowns after follow-up periods 0,3,6,12 months.