Comparing two different dental bridge designs made of translucent zirconia

INTERVENTION: Patients have been divided randomly into two group: Group A: received anatomic designed translucent zirconia bridges. Group B: received traditional designed translucent zirconia bridges. Follow up for two years. CONDITION: Patients who have lost one tooth or more and in need for dental prosthesis. ; Oral Health PRIMARY OUTCOME: ; Measured using visual inspection at one month, 6 months, one year, two years:; 1. Prothesis fracture: no fracture/color change or small fracture/zirconia fracture/complete fracture in the prosthesis; 2. Marginal fit: complete fit/there is evidence of leakage/the probe can access the prothesis/prothesis is movable; 3. Discoloration: no discoloration/surface discoloration/discoloration towards the pulb; SECONDARY OUTCOME: ; Oral health index collected using oral examination and with UNC15 probe (university of North Carolina). Oral data collected from each patient on three different time intervals (after one month, after 6 months, after one year, after two years); 1. Plaque index (PI); 2. Gingival index (GI); 3. Decayed, missing, filled teeth index; INCLUSION CRITERIA: 1. Lost second premolar in one side or more 2. Good oral hygiene 3. The pontics have good stability 4. Absence of oral dysfunction