Immediate Versus Delayed Loading of Maxillary Overdenture Implants

The primary objective of this study is to evaluate radiographically at 6, 12, 24, and 36 months post-loading the performance of the BLX Roxolid™ implants placed using a flapless guided surgery and immediately loaded with a maxillary overdenture versus delayed loading 3 months after surgical placement. The outcome will be evaluated using peri-implant, radiographic bone level changes from baseline to 6, 12, 24, and 36 months post-implant placement. The secondary objectives include evaluation of the condition of the peri-implant mucosa (pocket depth and bleeding on probing); Implant survival at 6, 12, 24, and 36 months; The nature and the frequency of surgical and prosthetic complications; Patient-centred outcomes (OHIP 14). An initial evaluation will be conducted to determine whether a patient meets the study inclusion criteria. This evaluation will include medical history, clinical examination, and radiographic examination (OPT). A pre-operative prosthetic evaluation of the existing prostheses will be made to establish their quality and the need for a new set of complete dentures before the implant placement. The maxillary denture will be used as a radiographic guide for the pre-treatment CBCT assessment. The tridimensional image obtained with the CBCT will be used for the surgical planning of the implant positioning using a dedicated implant planning software (coDiagnostix, Dental Wings Gbmh, Chemniz Germany) and a stereo-lithographic surgical guide will obtained using a 3D printer (Formlab 3B, Formlabs Inc. Somerville MA.). The implants will be inserted under local anesthesia, following consumption of prophylactic antibiotic medications consisting of 2 grams of amoxicillin 1 hour before the surgical procedure. If the patient is allergic to penicillin or penicillin derivatives, azithromycin or other classes of antibiotics will be administered according to ADA guidelines. The implant placement will be performed using the stereo-lithographic surgical guide. A small crestal incision and a minimal flap elevation will be performed in the location of the implant sites. The osteotomy site will be prepared following the drilling sequence provided by the manufacturer's surgical manual. The implant will be placed, and the maximum value of insertion torque (peak of insertion torque, IT) will be measured during the seating of the most coronal implant threads using the surgical unit (W\&H, Burmoos, Austria) and recorded as 20, 30, 40, 50 N/cm IT category. In case of IT lower than 20 N/cm the patient will be excluded from the study and the implant treatment will be completed following the standard delayed protocol. After implant placement, the patient will be randomly allocated to the test or control group. BLX Roxolid dental implants will be used, and length and size will be chosen based on the available bone volume. A minimum amount of bone at the 2nd premolar position to house a 3.5 x 10 mm BLX-Roxolid will be required. The patient will be randomly assigned to have their implants immediately loaded or conventionally loaded/delayed. The randomization will be computer-generated and the subject's assignment will be placed in a sealed envelope. On the day of surgery, after the implants are placed, the investigators will open the envelope to see which group the patient has been assigned to. If assigned to the test group, the denture will be immediately connected to the implants. The abutment screw will be torqued at 15 Ncm. The Novaloc cap attachments will be picked up intra-orally using cold-curing resin. To avoid contact of the resin with the surgical wound, a circular portion of a sterile rubber dam sheet will be adapted on the cap attachment once placed on the abutment during the pickup procedure. Occlusion is then checked and adjusted if necessary as well as the adaptation on the residual ridges and the patient is dismissed. If assigned to the control group, a cover screw will be seated on the implants and the flap will be sutured for submerged healing. After 3 months of healing the implants will be exposed and connected to the prosthesis following the same prosthetic protocol as described for the test group. The abutment screw will be torqued at 35 Ncm. As per post-surgical instructions, the patients will be asked not to brush the operated areas and to rinse instead with 0,12% chlorhexidine solution twice a day for 1 minute for 14 days. Pain control is provided with 400 mg ibuprofen, as needed. A soft diet is recommended for 2 weeks. The patients in the test group will be instructed not to remove the prosthesis for one week. The patients in the control group will be asked not to wear the denture for 7 days. Patients will be recalled at 1, 2, 4, 12 weeks, and 6, 12, 24, and 36 months after surgery. At the post-operative visit occlusion will be checked, as well as stability and retention of the prostheses and the need for any prosthetic maintenance. At 12 weeks the test group patient will have the abutment screw torqued at 35 Ncm. The control group patient will have the implant exposed and connected to Novaloc using a 35 Ncm torque. Periapical radiographs will be taken at abutment connection and 6, 12, 24, 36 months visit by paralleling technique using a Rinnâ (Dentsply Rinn, Elgin, Illinois, USA) film holder. The film holder will be indexed on the attachment so that the film position can be reproduced for the follow-up radiographs. All patient complaints or any complications resulting from a change in health status from baseline or any implant-related complications such as pain, paraesthesia, or peri-implant infection will be recorded as an adverse event in the CRF and will be monitored until the condition is resolved. OHIP-14 questionnaire will be administered at baseline, at 4 weeks post-surgery, and months 6, 12, 24, and 36 months.

• Pocket Depth of the peri-implant mucosa [Time frame: 36 months]
• Bleeding on probing of the peri-implant mucosa [Time frame: 36 months]
• Implant survival [Time frame: 36 months]
• Complications [Time frame: 36 months]
• Patient-centered outcomes [Time frame: 36 months]