Computer-guided implant placement and full-arch immediate loading with digitally prefabricated provisional prostheses without model: a prospective pilot case series

Background : Computer- guided surgery has been proposed to reduce the time between implant placement and provisional prostheses delivery. According to recent articles, guided surgery has shown an acceptable level of accuracy. Digital workflow could eliminate several treatment steps, such as impression taking, vertical dimension recording and the need for a reinforcement of the interim prostheses, due to the use of novel CAD- CAM materials. Aim/Hypothesis : The aim of this study is to evaluate the one- year results of digitally prefabricated PMMA provisional prosthesis for full- arch immediate loading when using computer guided surgery. Materials and Methods : The protocol involved the use of two surgical guides: the first was mucosa or teeth- supported, to drill the holes for fixating pins, the second guide was placed after raising a full- thickness flap and was supported by pins as well as soft or hard tissue distal support. Osteotomies and implant placement were performed through the surgical guide. Immediate loading was performed. The Screw- retained abutments (SRA) previously selected in the planning software were inserted. Interim titanium copings were, then, screwed on SRA. All patients received full- arch immediate loading with the prefabricated interim prosthesis, positioned with the same pins of the surgical guides. Prostheses were directly connected to titanium copings with a flowable resin. The prostheses were then unscrewed and polished; the connectors to the pins were cut off. The prostheses were delivered to the patient. Patents left the clinic with the interim fixed prosthesis the same day of surgery. Results : A total of 37 dental implants were placed in seven patients. One implant resulted in failure. All the prostheses had one year of functional loading to simulate the long provisional faze. No fracture of any kind occurred during the whole period of the prosthesis in situ. In all cases, interim prostheses allowed the insertion of titanium copings without need of wholes enlargement or adaptation. However, cases with tilted implants appear to be more technique sensitive, with tilted implants that should be placed in the exact planned position to let the corresponding SRA axis match with the axis of the holes in the prosthesis. Several studies demonstrate that patients use provisional prosthesis for several months. In the present study, milled PMMA restorations proved to be durable enough during the long provisional faze. Main limitation of this study is the small sample enrolled, however, the other studies in literature reporting data on prefabricated prostheses present just case- reports. Conclusions and Clinical Implications : With the limitations of the present study, the authors conclude that digitally prefabricated provisional prosthesis for full- arch immediate loading might be a valid alternative treatment modality when using computer guided surgery. CADCAM restorations are associated with less complications compared with conventional, as well as reduced treatment time. Analyzing the post- op CBCT data, the researchers conclude that suggested treatment modality offers predictable surgical and prosthetic outcomes.