Effect of Geometric Modifications of Implant Scan Bodies

Effect of Geometric Modifications of Implant Scan Bodies Compared to Conventional Transfer Techniques on Passivity of Mandibular All on Four Restorations

The aim of this clinical study will be the effect of geometric modifications of implant scan bodies compared to conventional transfer techniques on passivity of all on four mandibular restorations

The aim of this study will be the effect of geometric modifications of implant scan bodies compared to conventional transfer techniques on passivity of all on four mandibular restorations. Evaluation method: The trueness of the final impression and the passivity of the final prosthesis will be evaluated by two methods: Invitro evaluation For each patient in every group, the standard tessellation language (STL) files of scanned impressions will be superimposed on the reference file to determine the 3D surface, linear, and angular position analysis. The STL files for both frameworks will be superimposed on the reference file to determine the passivity. In vivo (Clinical) evaluation Radiographic evaluation using long cone parallel technique will be done for the framework after 6 month (T6) after one year (T12), and after 18 month (T18) from insertion.

For group (I): For each patient, two final impressions will be made a) Final impression will be done by conventional one-step impression technique.For the same patient, another final impression using unmodified scan bodies will be done by direct intraoral scan technique. For group (II): For each patient, two final impressions will be made a) Final impression will be done by conventional one-step impression technique.For the same patient another final impression using subtractive modified scan bodies will be done by direct intraoral scan technique. Conventional impression for both groups will be poured into stone cast with multiunit abutments analogues, then scanned to be as a reference file for each patient.

Final impression will be done by conventional one-step impression technique. For the same patient, another final impression using unmodified scan bodies will be done by direct intraoral scan technique.

Final impression will be done by conventional one-step impression technique. For the same patient another final impression using subtractive modified scan bodies will be done by direct intraoral scan technique

For each patient, implant supported mandibular hybrid prosthesis will be fabricated digitally. Frameworks will be tried in patient's mouth, scanned intraorally by intraoral scanner (IOS).

For each patient in every group, the standard tessellation language (STL) files of scanned impressions will be superimposed on the reference file to determine the 3D surface, linear, and angular position analysis

Inclusion Criteria: 1. All selected patients will have four implants placed in the mandibular interforaminal region according to all -on -four concept. 2. All selected patients have a healthy mucosa and with no clinical complications. 3. All patients are cooperative and approve the proposed treatment protocol. Exclusion Criteria: 1. Patients who reject to participate in the study. 2. Patients who need implant placement as a result of previous implant failure.