LAUSR

Computer-aided design and computer-aided manufacturing (CAD/CAM) technology has revolutionized mandibular reconstructive surgery. The possibilities of planning margins of bone resection, flap segmentation, and plate design allow highly precise reconstructions with great improvement of functional and esthetic results (Rana et al., 2012). Despite some initial concerns limiting the application of these systems, daily practice and several reports in the literature have resolved many of these issues (Wilde, Cornelius, & Schramm, 2014). In particular, the accuracy of planning transfer from virtual planning into the operating room, precision of reconstructive plates, and reliability of cutting guides have been largely documented in the international literature (Tarsitano, Ciocca, Scotti, & Marchetti, 2016; Wilde et al., 2015). Cost is the greatest factor limiting the adoption of such technologies, but recent studies have suggested that sparing of surgical time and increasingly accurate results minimize this problem, and several reports indicate that the costs are comparable to those of freehand procedures (Bolzoni et al., 2019). A careful literature review indicated that the majority of articles are focused on the aspects mentioned above, such as accuracy, costs, and functional or esthetic results. Deek and Wei (2016) reviewed their own experience with CAD/CAM reconstructive systems, and concluded that the literature is lacking a consensus on the indications and limitations of these techniques, underlining the primary relevance of these aspects in the validation of new technologies. Indeed, despite the topic is quite exhaust and fewnew information can be added to literature, it is still useful to determine which subgroups of patients can benefit from such systems and which others can be approached using freehand procedures because the advantages of custom-made reconstructions are not substantial. Our multicenter group, which includes 10 Maxillofacial Surgery Units in 7 different regions of Italy, developed a questionnaire (Data S1) focusing on indications for CAD/CAM mandibular reconstruction consisting of 6 domains, each composed of multiple queries, with a total of 36 items. Domain 1 inspected sites of mandibular defects, Domain 2 evaluated the impact of number of fibular segments on indications, Domain 3 focused on patient features, Domain 4 assessed the importance of histological diagnosis, Domain 5 analyzed indications based on the possibility of intraoperative preplating, and Domain 6 was used to assess whether the access route chosen was an important variable. The questionnaire was submitted to 20 surgeons belonging to the group with different ages and expertise, and they were asked to assess how each item counted in the decision of whether to use a CAD/CAM reconstructive system in each proposed situation, giving a score ranging from 0 to 10, with 0 indicating “useless” and 10 indicating “indispensable.” Then the scores were collected and the mean values were chosen to assess the opinion of the whole group. Of course, without any concrete evidence such as physiologic or biomechanical or any evidence directly from the clinical arena, such opinions are inherently biased. For example, technology availability or costs would vary significantly throughout international community and thus an opinion onwhen to apply this technology could be different elsewhere. However, despite the relevance of the survey should be considered limited to Italian country and its scientific value is biased by the small number of surgeons and centers enrolled, some interesting points emerged and it seemed to be useful to share these with the international community. Highest scores, meaning strong indication for CAD/CAM reconstruction, were achieved for complex defects (symphysis + body + ramus/ condyle) with a value of 9.05, or when more than three segments were planned (8.8). This could be explained not only by the complexity of the case but also by the time spared in the operating room, which is the most important parameter to amortize costs of the system. Also dentition and expectation of dental rehabilitation resulted to be important, with a score of 8.1: on the other hand in edentulous patients, millimeter-scale accuracy is not needed to achieve satisfactory reconstruction, while a few millimeters could bias a good reconstruction if occlusion is not preserved or if dental implants cannot be placed properly because the fibula is not in the ideal position in patients who have retained their teeth. For what concern diagnosis, CAD/CAM resulted to be strongly indicated in benign tumors (score 8.6) or other benign conditions, such as osteoradionecrosis, bisphosphonate-induced osteonecrosis, osteomyelitis, and so forth. These patients require the best results, as they are often young and fully dentate, with long-life expectancies, and dental rehabilitation is usually an integrated part of the treatment. Furthermore in these cases planning time is largely acceptable, while in malignant tumors it is still a variable to consider. On the other hand, when malignant tumors involving the mandible are treated, patients are usually older, neck dissection and soft tissue resection are required, radiation therapy is planned, and this biases the cosmetic and functional outcomes more than the accuracy of bone reconstruction, thus reducing the strength of indication for CAD/CAM. The highest scores of the survey (8.9) were achieved for patients when preplating is not feasible, because of tumors enveloping the mandible or of absence of jaw in secondary reconstructions. In these situations, CAD/CAM reconstruction is indeed very useful: the possibility of using mirroring to properly define mandibular angle position, Received: 27 June 2019 Revised: 25 July 2019 Accepted: 9 August 2019