Steps in short: Single tooth in the esthetic zone requiring full coverage crown is prepared to receive an all-ceramic crown, The restorations will be divided into two groups: I: Teeth receiving restorations fabricated from Lithium disilicate II: Teeth receiving restorations fabricated from yttria stabilized multilayered zirconia. Shade will be measured using intraoral spectrophotometer and evaluated. The colour difference (ΔE) will be calculated for each sample using the following equation: ΔE =[(ΔL) ²+(Δa) ² + (Δb) ²] ½, ΔE (perceptibility threshold) will be evaluated for each group. Participant timeline the patient will be treated in visits designated as follows: Visit 1: Preoperative records, face-to-face adherence reminder session, clinical, radiographic for examination, intraoral photographs and primary impression (Alginate impression) diagnostic cast construction. Visit 2: teeth preparation and secondary impression using addition silicone rubber base material and temporary restoration. Visit 3: placement and permanent cementation of the final restoration using resin cement.