DIMENSIONAL ACCURACY OF DIRECT AND INDIRECT IMPLANT IMPRESSION TECHNIQUES FOR COMPLETELY EDENTULOUS PATIENTS

Background: Accurate recording of implant location is required for a successful definitive restoration.
Aim: This study was conducted to compare the accuracy of two implant impression techniques (direct and indirect) in transferring implant positions to the master casts in comparison to implant position in patients’ mouth using radiographic imaging.
Materials and Methods: Ten completely edentulous male patients were selected. 2 Root-form implants 3.7 mm in diameter and 16 mm in length were utilized in this study in the canine regions. For each patient two special trays were fabricated, one for the registration of direct impression technique and the other for the indirect impression technique. Cone beam computed tomography (CBCT radiograph) was done for all patients, the casts obtained from direct and indirect implant impression techniques were taken to evaluate the accuracy of the two impression techniques in comparison with the patients’ radiographs regarding the distance between the implants. The horizontal dimensional accuracy of the impression techniques was determined by measuring the inter-implants’ distance in the x-axis between the copings. Measurements were done on radiographic images of the following; casts obtained from direct impression technique, casts obtained from indirect implant impression technique and radiographs of patients.
Results: The mean and SD values of casts radiographs obtained from both impression techniques and from patients’ radiographs were calculated. Group I (Deviation of distance between direct impression technique and patients’ radiograph) had a mean value of 1.45mm (SD 0.03); Group II (Deviation of distance between indirect impression technique and patients’ radiograph) had a mean value of 2.08 mm (SD 0.04). The direct impression technique showed more accurate results.
Conclusion: Casts obtained from the direct impression technique were significantly more accurate than those obtained from indirect impression technique. Comparison of both impression techniques retrieved from patients in relation to patients’ CBCT provided more reliable results than in vitro studies. So this study suggests that direct impression technique is more accurate.