The aim of the study was to evaluate the marginal bone status around two types of implant abutment junction, which are platform switched and non-platform switched types using cone beam CT. 8 patients, 4 males and 4 females with an average age 32 year (range from 22 to 43 years), with posterior edentulous area of the mandible were included in this study. A thorough preoperative assessment of all patients was carried out including history taking, clinical examination including plaque and gingival index and radiographic examination. Study casts were created for evaluation of edentulous areas and occlusion, cone beam computed tomography(CBCT) scans were used as the final investigation, it was possible to correctly assess the width of each implant site, the thickness and density of the cortical plates and the cancellous bone, as well as the ridge angulation and a virtual implant treatment plane was performed. The implants used in this study were 3.4 mm in diameter, Submerged superline fixtures with dual abutments and non-submerged tissue level simple line implants with dual abutments (Dentium Co., Ltd., Gangnam-gu, Seoul, Korea). Implant insertion was performed according to manufacturer's instructions. Non submerged installation procedures were performed. Para crestal incisions with releasing incisions were done at surgical sites and Full-thickness flaps were reflected exposing the alveolar ridge, Sequential drills were used until the 3.4 diameter final drill under constant irrigation. Abutments were installed at time of surgery, and flaps were closed by interrupted sutures using 3"0" silk. At 2 months, a definitive abutment level impression was made and Acrylic restorations were cemented to the abutments. Modified plaque index (mPlI) and modified Sulcus Bleeding Index (mBI) was carried out was carried out. Cone beam computed tomography (CBCT) has been carried out to evaluate buccal and lingual crestal bone changes . All radiographs for each case were taken under constant conditions. CBCT scans were carried out at baseline and 9 months post-surgically. The Comparison between the two groups showed no statistically significant difference between amounts of crestal bone loss in the two groups after 9 months.