Diagnostic value of Digital Radiography in Gap Detection of Implant-Abutment Connection with Zirconia Abutments in Different vertical X-ray Projection Angles

Introduction: Accurate seating of abutments on implants is an important factor for long term success of implant supported restorations. Among different methods of evaluating abutment seating, radiography is most commonly used, while some clinical factors such as angulation of radiography film and radiography tube can adversely affect its diagnostic value. Aim: To evaluate diagnostic value of digital periapical radiographs in terms of sensitivity, specificity and accuracy of gap detection at implant-abutment connection with different angles of X-ray projection when using a zirconia abutment. Materials and Methods: In this in vitro study radiographs were made of three different implant connections (internal tri-channel, external hex and internal hex with platform switching) to which zirconia abutments were fastened, once with and once without using a spacer between implant and abutment. Radiographs were taken at different projection angles of -20, -15, -10, -5, 0, +5, +10, +15, and +20. Then 10 prosthodontists were asked to assess all the radiographs, two times for each one with an interval of 10 days. Sensitivity, specificity and accuracy indices were calculated for each system. Results: Findings showed that sensitivity of gap detection in all study groups was amongst acceptable range (85-100%). In general external hex connection system showed better results (95-100%) while the platform switching internal hex system had the weakest results (85-100%). Conclusion: Angle of X-ray projection is better to be between -10 to +10 when evaluating complete seat of zirconia abutments on implants especially if a platform switching system is used.