Bleeding is a common complication or, at least, one contemplated in the context of any surgical procedure: in this sense, oral surgery and, in particular, implant surgery are no exception. In most cases, the bleeding is limited in terms of quantity and time, and can easily be managed to employ compressive hemostasis or other local operations.
The involvement of vascular structures, especially arterial ones, which are relatively important, can lead to a profusion of bleeding: even in these cases, it is difficult that complications of this type, especially in healthy patients, can constitute serious obstacles to circulatory compensation. The problems will, in most cases, be limited locally and can be traced back to the visual obstacle at the level of the operating field. The most severe cases will be more easily linked to obstruction of the upper airways and, therefore, will represent respiratory emergencies even before distributive and circulatory.
A relatively high-risk hemorrhagic area in implant surgery is the lingual side of the mandibular arch.
Several reports on the subject refer to the perforation of the lingual cortical during the drilling phase as a procedural trigger. Some of these cases hesitate in a real respiratory emergency resulting from blood accumulation at the level of the oral floor with the lifting of the same and risk of swallowing the tongue.
When questioning the vascular origin of these bleedings, Woo observed the high risk of sublingual artery involvement. Isaacson proposed that these may be collateral branches of the same sublingual artery and, also, of the submental artery. These indications were difficult to interpret and, for this reason, more recently, Fujita conducted an anatomical study on the subject.
In this regard, anatomical studies are not limited to ascertaining the origin of the vessels in the region (i.e., the lingual and facial arteries) but can assess the site of penetration of the branches at the bone level.
Loukas’ studies focus again on the sublingual artery, which in this region provides bilateral branches, then anastomizes and, finally, emits perforating branches close to the midline.
Other reports have instead reported cases of submental artery perforation.
Another aspect to be evaluated is the need to further study the course (and possible variations in this regard) of the lingual artery, which leads upwards, is the facial artery, which instead runs on the lower part of the muscle miloideo, a structure that is conventionally identified as the floor of the oral cavity.
The study referred to above, whose indications will be taken up in the second part of the text, has precisely considered the vascular anatomy of the region. As is desirable, attention is paid to the possible forms of variability, even at the level of anastomosis and perforation traits, to reread the implant complication on an anatomical basis.
Fujita and colleagues conducted a major anatomical study that considered a total of 50 corpses, of which five were unfixed. The study could be exposed to an aspect of criticality on an ethnic basis, as it considered only adult subjects (aged between 59 and 93 years) of Japanese origin. This problem is, however, at least partly overcome by a large number of samples studied.
The dissection of the anterior mandibular region, lingual side, was conducted as follows: the mucous membrane of the oral floor was removed intraorally. On the skin side, after the dissection of the teguments themselves, the platysma muscle was excised.
The pathway of the lingual artery was evaluated starting from the origin at the level of the external carotid artery; the excision of the halibut muscle was also necessary. The lingual artery runs in a posterior-anterior direction, medially to the same ioglossal muscle. The deep lingual artery releases two to three branches and extends from the two-thirds covered posteriorly by the halibut muscle to the body of the tongue. This morphology was homogeneous in all the samples evaluated in the study.
The pattern of the sublingual and submental arteries, the same called for by Isaacson, was observed, respectively, extra orally and from the lower margin of the mandible.
The sublingual artery was present in 55% of cases (each patient was evaluated bilaterally, so 100 sides were considered). In all the remaining 45 cases, the deficit was vicariate by branches of the submental artery, perforating the mylohyoid muscle, in one-third of the cases (26.7% of the 45) on the anterior third.
In nine of the 55 cases; instead, the sublingual artery was anastomosed to the same submental artery.
The submental perforates the mylohyoid muscle at an average linear distance of 25.1 mm (± 10.6). At this point, the vessel has an average pario diameter of 2.03 (± 0.69) mm.
The distal arterial branches were evaluated according to criteria defined by the aforementioned Loukas, thus identifying an ascending branch directed to the alveolar crest, a median branch covering the mucosa and finally a descending branch. The most constant was the ascending branch, present in 94% of cases, followed in order by the median (72%) and descending branch (52%).
In the final analysis, the terminal branches perforating the alveolar mucosa on the lingual side, in the incisal area, and the premolar area, were searched. These results were respectively affected by branches of a single artery in 44 and 17% of cases. In 37% of cases, both were involved. Under no circumstances, however, were two branches able to reach the same area. In the same way, no upward branch has reached the molar region.
To prevent the involvement of these vessels, Fujita recommends identifying the location of the lingual foramen on computer tomography.