The effect of different height titanium base abutments on the internal fit of a zirconia crown

Background and objectives. This in vitro study aimed to evaluate the effect of titanium base abutment height on the internal fit of CAD/CAM-fabricated zirconia crowns. Achieving a precise internal fit is critical to the long-term success of implant-supported restorations, yet limited data exist regarding how abutment height may influence this parameter. Materials and methods. Twenty implant analogues made of Grade 4 titanium (diameters: 4.5 mm and 3.75 mm; lengths: 12 mm and 13 mm) and twenty titanium base abutments (diameter: 3 mm) with two different sulcular heights (6 mm and 4 mm), along with their corresponding scan bodies, were selected. The specimens were divided into two groups of 10 each. Group A employed Dentium® scan bodies and analogues with 6 mm abutment height, while Group B used SGS® scan bodies and analogues with 4 mm abutment height. Crown design and milling were performed using a standardized CAD/CAM workflow. Internal fit was assessed using the digital silicone replica technique and 3D analysis with Geomagic Control X software, both before and after thermocycling. Mechanical performance was evaluated by measuring removal torque values (RTVs) before and after cycli