The
clinical relevance of this anatomic feature is underlined by the growing
diffusion of implant treatments at the mandibular midline and by reports of
complications deriving from such procedures. Interforaminal section is a best
choice for the placement of the implant which supports the fixed partial
dentures or over dentures. One of the autologous area in the oral cavity is the
symphysis which required excessive ridge augmentations. Lingual artery supplies
the arteries from the submental branch and the sublingual branch which includes
genioglossus muscles, geniohyoid, sublingual gland, mylohyoid, lingual gingiva and,
mucous membranes in the floor of the mouth floor.

From
the branch of the inferior alveolar artery mental artery arises and communicate
with the sublingual artery in the region of the internal mandible (9WU1 ).
Even though the interforaminal is comparatively a safe region for to place the
implants, the perforation in the lingual cortex can leads to the severe
haemorrhage during the placement of the implant. Further if drilling ruptures
lingual periosteum, the bleeding might be enhanced due to damage in the
anatomical structures in the sublingual spaces, these results in the hematoma
in the mouth floor. Apart from the interforaminal region, the lingual foramen
present in the molar area is also well reported (9WU2 ).
The cadaveric studies showed that the sublingual and submental arteries both
were perforated through the lingual foramina in the mandible (9). WU3 

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Subsequent
to the tooth extraction, horizontal bone loss is primarily in labial side. This
pattern of resorption leads to lingually angulated trajectory of the mandible.
If the atrophying mandible is not noticed prior to the implant placement, the
lingual perforation complication will increase. The bony architecture and its
surrounding anatomical structures were well depicted through the CT which is
frequently used imaging technique. The three dimensional assessment of the particular
area is extremely suggested to achieve favourable prosthetic angulations which
also excludes the complications.24WU4 

            The recent studies emphasizes that
the structures which increases the risk of complications includes the anterior
dilation of inferior alveolar neural tubes, concavity of lingual bones, lingual
foramina, and lingual tubes. However, there are cases were atypical haemorrhage
have been caused due to lingual plate perforation (8)WU5 .
The mucosal branches which are present along with the lingual side of the mandible
requires  special care pre surgical
period, as they are known to deposit lingual cortical bone into the mandible (9WU6 ).

The
bleeding along with severe edema, in the process of the implant surgery due to
the direct damage of the sublingual arteries followed by lingual cortical bone
perforation. If the bleeding is delayed the possibility of the bleeding in sublingual
artery branch have to be considered. However the risk of bleeding should be
assessed in patients with hypertension / patients who were on anticoagulation
drugs. The pre surgical assessment is mandatory if foramen’s diameter is higher
than 1mm in CT scan.  Increased risk is
prevalent among the elderly patients who are in the need of alveoloplasty (for
dental procedurs) and patients with severe alveolar bone atrophy. As in these
patients lingual foramina is closer to alveolar ridge and the frequency of appearance
of lingual foramina is higher.  

Anatomical
considerations:

Clinical considerations
related to sublingual haemorrhage:

The
anatomical feature and its clinical relevance underpinned by the increasing
implant treatments in the mandibular midline and the increasing report of the complications
during such procedures. Secondary to the implant treatment, life threatening
haemorrhage and haematoma formation in the floor of the mouth were recorded in
many earlier reports.  In humans, three
major subdivision namely superior, inferior and the middle sublingual alveolar
branches have been identified.  In
general facial artery is the fourth successive and third anterior branches of the
external carotid artery, except it originates along with the lingual artery
through the common linguofacial trunk.

This
anatomical attention lays the basic foundation for the role of submental artery
is either a major vessel or a supplementary vessel in this region and deserving
the consideration so as to understand the nature of haemorrhages descending
from the perforation of the mandibular lingual cortical during implant surgery.
The mechanical injury in the branches of the arterial plexus might possibly
leads to the dangerous haemorrhage. The elaborate knowledge on the anatomy of the
fine arterial structures is necessary for the implant surgeries. From the level
of the hyoid bone, lingual artery is the third sequential and second anterior
branch from the external carotid artery. This lingual artery provides the body
and the top of the tongue through the terminating deep dorsal branches along
with lingual artery. At the frontal border of the hyoglossus muscle, the lingual
artery leads to sublingual artery.   

Recommendations:

Clinically
attention has to be given to recognize the situation where this risk might
occur. Subsequently, following recommendations has to be followed. An
appropriate preoperative planning is mandatory before any surgical procedures
concerning the median mandible, bearing in mind that the degree of osseous
atrophy along with the mandibular inclination. If necessary radiographic examination
of these endoosseous canals through computed tomography. An accurate knowledge
on the anatomy of the region is necessary. The positioning of implants in the mandibular
midline has to be given most priority. A wise opting of even number of implants
in the interforaminal region can avoids the risk of trauma to the lingual
cortical plate of the mandibular midline.

Conclusion:

The
present review showed that the variations in the anatomical landmarks and the
measurements of lingual foramen vary in every individuals, thus it is important
to think about the lingual foramen during the planning session for surgery and
particularly during the placement of anterior mandibular implants, to avoid post-operative
related complications. The clinicians has to note the position of the midline
mandibular lingual canal and should approach with precautions, specifically if the
alveolar ridge has to be decreased prior to the placement of the implant.