The reported results showed that eventual surgical errors may arise during surgical procedures. When intraoperatively detected, they can be solved at the same moment avoiding a secondary corrective surgery.
No guidelines exist in the literature regarding the indications of using intraoperative imaging in the maxillofacial region [15]. However, the main indication of ICBCT reported in the literature was facial trauma surgery Alternatively to the literature, the main indication of ICBCT in this study was orthognathic surgery. The explanation is that the study was performed in a pediatric hospital, where the incidence of facial trauma surgery was low. In contrast, the vast majority of patients had an underlying cleft lip and palate and other craniofacial syndromes and therefore underwent orthognathic (60.37%) and reconstructive (24.52%) surgery. In the same context, the mean age in the study was 15.96 +/- 3.31 (SD), which is lower compared to other samples from different studies related to ICBCT in maxillofacial surgeries, where the mean age described is 37.4 to 37.5 years [18, 19].
In the present study, the total revision rate was 18.87%, including minor adjustments and refinements. The major revision rate was 7.55%. In other words, these patients would have needed secondary surgery. An example is shown in Fig. 4.
Compared to other studies, it was a low revision rate, probably because our protocol also involves 3D virtual surgical planning, printing of 3D stereolithographic models and CAD/CAM customized implants. Alasraj et al. reported a revision rate of 50% in a retrospective study composed of 22 patients with facial fractures [20]. Other authors described in a retrospective study of 71 patients with ZMC fractures a revision rate of 23.9% [19].
Beyond facial trauma surgery, other indications of ICBCT are described in the literature [14]. Although the use of ICBCT in orthognathic surgery to date is limited, some publications have reported its usefulness: R. Seeberger et al., evaluated in 22 patients the proximal condylar segment positioning with high oblique sagittal split osteotomy with ICBCT [13]. In another study, ICBCT was used to ensure screw penetration and depth to avoid inferior alveolar nerve injury during bilateral sagittal split osteotomy [21]. However, the authors have designed and implemented an extensive check-list protocol for evaluation of ICBCT in maxilla-mandibular surgery (Fig. 3), which helps to properly evaluate intraoperative results while reduces ICBCT assessment time.
Moreover, ICBCT can be useful to look for foreign bodies, as described in patients with gunshot injuries [11]. Our sample reported one patient with a non-palpable 5mm sialolithiasis in the Wharton’s duct which was not found during surgery. An ICBCT was performed to locate its new position and then it was easily reached and removed. As in our sample, it is described the use of ICBCT in bone remodeling [17].
Similarly, there is lack of bibliography regarding other indications of ICBCT such as, reconstruction of temporomandibular joint with prosthesis and iliac bone graft, among others. However, the authors believe ICBCT with superimposition of preoperative data is useful in the abovementioned surgeries in order to check surgical accuracy.
On the other hand, ICBCT entails two main concerns: radiation exposure and additional operative time. First, radiation dosage for a maxillofacial fan beam CT scan is approximately 2–5 mSv and for a CBCT scan is approximately 0.35 mSv [22]. In the present study, a low-dose protocol was performed, with doses of 0.56 mSv for each CBCT. Indeed, those patients who did not undergo an intraoperative CBCT, underwent a control postoperative CBCT scan, with a radiation dose of 1.31mSv. Second, although the additional operative time has not been recorded in the present study, it is described an average additional time between 14.9 and 18.5 minutes [18, 20]. However, in some situations where not a direct vision of the surgical field is provided, an ICBCT might reduce the operative time.
To sum up, based on this study and on the reviewed literature, the main advantages of ICBCT were 1) detecting and solving problems during the surgery, decreasing the need for additional secondary corrective surgeries; 2) direct field visualization might be reduced because surgical results can be checked intraoperatively, thus avoiding extensive surgical approaches; 3) imaging bone with high quality, comparable to conventional ICT, with low level of metal artifacts [15]; 4) low radiation exposure [22]; 5) if superimposition of preoperative data, minor adjustments can be done and a higher degree of accuracy can be reached. The main disadvantages of ICBCT were 1) limitations for soft tissue imaging; 2) although low radiation exposure, it is not a harmless method; 3) increasing operative time, although slight; 4) elevated costs, being difficult to establish the device in most hospitals.
The study has some limitations, such as it is a retrospective study, with the inherent bias involved. Moreover, imaging acquisition time was not been recorded.
Further high-quality prospective randomized clinical trials, with bigger sample size investigations in this topic are needed, as well as its combination with other new technologies such as intraoperative navigation and updated ICBCT indications and guidelines. ICBCT has a role not only in facial trauma, but also in orthognathic surgery and other maxillofacial pathologies. While adding a few minutes in operative time, it provides invaluable intraoperative information that can significantly lower the threshold for a surgical revision. In combination with superimposition of preoperative data, it potentially increases surgical precision.