Mandibular incisive canal in relation to periapical surgery.

The aim of the present paper is to emphasize the importance of the mandibular interforaminal neurovascular bundle with a case and make a warning to dentists and surgeons during oral and maxillofacial surgeries, such as implant replacement, bone harvesting, genioplasty, open reduction of a mandibular fracture, and cyst enucleations at this region. In this paper, we present a 58-year-old male who referred with pain and a tingling sensation on the left lower lip. After radiographical, extraoral and intraoral examinations, findings indicated the lesion to be a cyst which was related with a periapical lesion of the canine tooth and extracted socket of first premolar tooth. After removal of a cyst, the mandibular incisive nerve was documented which was in relation to cyst cavity.

Introduction

The mandibular incisive nerve (MIN) is described as a terminal branch of the inferior alveolar nerve and provides innervation to the mandibular anterior teeth. This nerve is located in a canal which is the extension of the mandibular canal.[12]

The mandibular intermental region is generally considered as a safe area, involving few risks of damage to vital anatomical structures. Nevertheless, the anatomic description of anterior mandibula, with its potential clinical effects, is still controversial. Some authors even neglect existence of a true incisive canal.[345]

Contrary to above-mentioned, in the literature, the interforaminal region is assumed to have an excellent risk benefit ratio, following chin bone harvesting, complications can occur on the donor side which involves intraoperative bleeding, pulp canal obliteration, as well as loss of pulp sensitivity of the anterior lower teeth, and the latter presenting neuropraxia of the MIN.[6] In addition, complications including pulsatile bleeding from the anterior mandibular incisive canal, hemorrhages, neuropathic pain, neurosensory disturbances, and failure of osteointegration of implants during or after the implant surgery were also reported in the interforaminal region of mandibula.[3578]

This presentation was conducted to remind the importance of the MIN before surgeries at the anterior region of the mandibula. Operations such as implant placement, bone harvesting, genioplasty, open reduction of a mandibular fracture, and cyst enucleation with a documented case with photos of the incisive nerve and mental nerve.

Case Report

A 58-year-old male patient, suffering from paresthesia of the left lower lip, was referred to the Near East University, Faculty of Dentistry, Department of Oral and Maxillofacial Surgery in Nicosia, Cyprus. The patient's chief complaints were pain at the left premolar region of the mandibula and a tingling sensation on the left lower lip. This sensory disorder had initiated 2 months previously. Despite taking painkillers, the condition had persisted. After the radiographic examination, there was a well-defined, unilocular, radiolucent area at the left premolar region of the mandibula. This lesion had a relationship with a periapical lesion of canine tooth and extracted socket of the first premolar tooth [Figure 1].

Figure 1

Preoperative panoramic view of the patient

Extraoral examination using sharp/dull and two-point discrimination tests revealed sensory disorders in mental nerve dermatome on the lower lip. The patient had facial symmetry and regional lymph nodes were palpable and not tender. Intraorally, there was a root of the left lower canine tooth which was tender on percussion but not on palpation. In addition, there was no swelling both extraorally and intraorally. Clinical and radiographic findings indicated the lesion to be a radicular cyst [Figure 1].

Treatment planned was surgical enucleation of the cystic lesion, followed by placement of platelet-rich fibrin (PRF) gel into the cystic cavity. Surgery was performed under local anesthesia, using nerve blocking agents in the inferior alveolar, lingual (regional anesthesia), and buccal nerves (infiltration anesthesia), (2 mL Ultracaine D-S Forte Ampul; Sanofi-Aventis). An incision was made and a mucoperiosteal flap was raised. After mucoperiosteal flap reflection, mental nerve and foramen mentale were seen and corticotomy was performed using a 1.6 mm round bur mounted on a W and H implanted surgical high-speed handpiece, at 40,000 rpm under abundant irrigation. Bone was removed and the top of the lesion was opened like a sinus window [Figure 2]. After enucleation of the cyst, a nerve which was found to be nervus incisivus was exposed [Figure 2]. After removal of the canine tooth, cavity of the cyst was cleaned with sterile physiologic saline solution containing no antibacterial agents and PRF gel was carefully placed inside the bony defect [Figure 2]. Following soft tissue closure with 3–0 silk sutures, patient was instructed to take amoxicillin (1000 mg) 3 times/day for five days and to use antiseptic (povidone-ıodine 7.5%) mouthwash 3 times/day for seven days. Flurbiprofen (100 mg) was also prescribed postoperatively, to be taken as required. Sutures were removed after seven days and the wound healed uneventfully. Furthermore, paresthesia had completely resolved after 2 months. At the 7th month follow-up, a panoramic radiograph showed that the lesion area was completely healed [Figure 3].

Figure 2

Mental nerve together with mandibular incisive nerve extension and the surgical site with application of platelet-rich fibrin

Figure 3

At the 7th month follow-up radiography indicated good healing on the site

Preparation of platelet-rich fibrin gel

PRF was prepared according to the technique described by Dohan et al.[9] Approximately 15 min before surgery, a blood sample was taken without anticoagulant in 10 mL glass-coated plastic tubes that were immediately centrifuged (Elektro-mag M415P) at 3000 rpm for 10 min. The platelet-poor plasma that accumulated at the top of the tubes was discarded. PRF was dissected approximately 2 mm below its contact point with the red corpuscles situated beneath, to include any remaining platelets that may have localized below the junction between the PRF and red corpuscles.[9] 10 mL tube produced one PRF clot, and it was adequate to fill the bony defect.

Discussion

In this presentation, we documented the incisive nerve and mental nerve [Figure 2] which are very important for complications at the anterior region of the mandibula. According to Juodzbalys et al.,[10] the mandibular incisive canal, mental foramen, and associated neurovascular bundle exist in different locations and possess many variations. Individual, gender, age, race, assessing technique used, and degree of edentulous alveolar bone atrophy largely influence these variations. de Souza Tolentino et al.[1] reported that cone beam computed tomography allows a greater accuracy in the diagnosis of anatomical variations in the jaws compared to panoramic radiograph. Mraiwa et al.[5] stated that both neurosensory disturbances and hemorrhages after implant surgery have been reported in anterior region of mandibula, for this reason should also pay particular attention to the anatomical peculiarities of this region to avoid any neurovascular complications. Fifty-five patients with suspected relationship between mandibular incisive canal and dental implant were included in Kütük et al.[8] study. Computed tomography scans were obtained from ten patients who had postoperative neuropathic pain. A three-dimensional software program was used to evaluate relationship between dental implant and the MIN. In all ten patients, an MIN perforation by at least one implant was observed. According to the results of this study, neuropathic pain may occur after implant surgery and the mandibular incisive canal and nerve perforation should be consider as a complication of implant surgery in the mandibular anterior area.

Conclusions

The presence, location, and dimensions of mandibular incisive canal are an additional required data needs to be elicited before planning oral and maxillofacial surgeries at the anterior region of mandibula and surgeons are responsible to prevent their patients from complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.