İmplantlı destekli kronlarda, kron tutuculuğunu artırmak için yapılan yüzey işlemlerinin etkilerinin karşılaştırılması
omparison of the effects of surface treatments for increasing the retention of implant-supported crowns. In the treatment of missing teeth it has become a preferred treatment option that is the use of implant abutments. Implant-supported fixed prostheses have two ways to be connected to the abutment which is a component of the implant; that the screw connection or to be cemented. Although there is no decision that one of two systems is better than the other, cemented implant-supported fixed prostheses are more commonly preferred because of ease of application, cost, less risk of fracture in the occlusal and aesthetic reasons. The retentiveness is the most common problem for cemented- implant supported fixed prosthesis. Improper preparation of abutment, insufficient distance between the arches, unsuitabl e tapered abutments and the properties of the inner surface of crowns that applied on abutments are the reasons of the retentiveness. The aim of our study is to compare the surface treatments that applied on abutments to improve the retention of crowns for cemented- implant supported fixed prosthesis. 55 implant analogs and abutments have been used in our study. All abutments are prepared 4 mm in height and combined with analogs. Then 35 Ncm torch applied properly about manufacturers' recomendations. All analogs were embedded in cylindrical acrylic blocks that have 11 mm diamater and 20 mm heights. 5 experimental groups were formed containing 11 samples; the control group, roughened group by acid etching, roughened group by milling, roughened group by sandblasting and roughened group by fiber laser etching. Any surface treatment was not applied to the control group. HCl and H₂SO4 are used for roughened group by acid etching. Spherical pits are formed in roughened group by milling. 250 µm Al₂O₃ particles sprayed to the surface for roughening the sanblasting group. In the fiber laser group, using the power of 20 W, 70 kHz frequency of the surface roughening is made. Cotton pellets are placed in the space of the occlusal surface of the abutment screw, and each abutment is sealed with a temporary filling material. Crowns were placed on abutments and zinc phosphate cement mixed and applied according to the manufacturers' recommendations, then a 5 kg weight was applied for 10 min. Excess cement was removed. After 24 hours, all samples were subjected to long aging process in the aging device 1000 rpm / 20 sec. Each coping was pulled from the abutment along the path of insertion using a specially fabricated jig with a universal testing machine at a crosshead speed 0.5 mm/min. The retentive force was determined as the maximum force required for coping removal. As a result of tensile tests applied to the abutment-crown sample implementation, the difference between those of the control group were statistically significant for all groups. However the tensile strength of the group, made using laser etching is defined as more than any other groups. Sandblasting and laser groups results of tensile tests showed considerably higher values than the other groups, but the difference was statistically significant. Laser etching process can be recommended instead of sandblasting for roughening the implant supported fixed prosthesis routinely. It can be said that, laser etching is more advantageous than sandblasting because of decreasing the risk of contamination.