Conventional Coronectomy vs Coronectomy in Combination Vital Pulp Treatment Using Calcium Silicate

The aim of this study was to compare the conventional coronectomy and the combined coronectomy technique with vital pulp treatment. The primary outcome of the study was to evaluate the success rates of two treatment techniques based on clinical and radiologic observations regarding inferior alveolar nerve injury, root exposure and formation of periapical lesion. The secondary outcome was to evaluate the change in periodontal condition of the second molar adjacent to the operation area, dentin bridge formation and root migration.

Between March 2018 and February 2022 eligible patients attended University Hospital for the removal of lower third molar with risk of inferior alveolar nerve (IAN) damage invited to the study. 60 teeth meeting the inclusion criteria in 52 participants were randomized to Test (with BiodentineTM, n=30) and Control (without BiodentineTM, n=30) groups. Neurological injury and post-operative pain were clinically evaluated at 12th months and 1st week, respectively. Root migration, dentin bridge formation and periapical lesion development were evaluated using Cone Beam Computed Tomography (CBCT) at 12th month. The change in the periodontal status of second molar was evaluated by measurement of pocket depth at 1st, 3rd and 12th months and the distance between base of the bone defect and the marginal crest and cemento-enamel junction and at 6th and 12th months month.

The surgical removal of mandibular third molar teeth is one of the most frequently performed oral surgical procedures. One of the complications might occur during surgical removal of these teeth is injury to inferior alveolar nerve (IAN) which may lead to altered or loss of sensation to lower lip, chin, teeth and gingiva on the operated side. The risk for IAN injury may not be avoidable, even though the surgery was performed by an experienced surgeon and the positional relationship between the mandibular third molar and IAN was assessed accurately prior to surgery.

Pericoronitis, dental caries and periodontal disease are the most common pathologies associated with mandibular third molar teeth. Theoretically, removal of crown part of the teeth with a vital pulp and leaving the roots behind might be adequate to relive clinical symptoms arise from these pathologies. This technique was first described by Ecuyer and Debien in 1984 as coronectomy to prevent injury in case of close relationship of mandibular third molar with inferior IAN.

As shown previously in randomized clinical trials, fewer complications in terms of post-operative pain, IAN deficiency and dry socket were observed after coronectomy. Systematic reviews have confirmed that incidence of IAN injury was lower with coronectomy when compared to total removal in case of the lower third molar radiographically closely related with the IAN. Nerve injury was reported to occur in up to 20% of cases temporarily and 1-4% of cases permanently after total extraction, whereas 0-5.5% of cases temporarily after coronectomy.

Radiographic assessment using panaromic radiographs is the first step for coronectomy procedure. Presence of the interruption of the white line of the mandibular canal wall, darkening around the root(s), diverging of the mandibular canal, narrowing of the mandibular canal, narrowing of the root(s) and deflection of the root(s) are the indicators of increased risk for IAN injury. In recent years, cone beam computer tomography (CBCT) scanning is widely used method for further investigation to demonstrate the three-dimensional relationship between the tooth and IAN. Additionally, eligibility of the third molar for coronectomy should also be evaluated to be free of caries, pulpal inflammation and abnormal surrounding tissue. Coronectomy is contraindicated for non-compromised patients with good healing potential due to medical conditions such as diabetics, long-term steroid use, chemotherapy or radiotherapy.

One of the possible complications after coronectomy is migration and eruption of the roots left in the bone. Bone formation over the retained roots is expected to avoid eruption of these roots in the oral cavity. In case of eruption, remaining roots should be extracted. Another possible complication is periapical lesion development due to necrosis of the pulp. With conventional coronectomy procedure, no pulp treatment of the remaining roots is performed. Previous in vivo studies demonstrated that pulp retained vital after coronectomy. However, presence of pain and infection after coronectomy was reported in randomized clinical trials. Vital pulp treatment of the remaining roots with a bioactive material may have the potential to enhance both dentin and bone formation leading to reduced complications related with periapical inflammation and tooth migration.

In the literature, there is no study concerned with the clinical success of coronecyomy in combination with vital pulp treatment, except a case report. Therefore, the aim of this randomized clinical trial was to compare clinical success of conventional coronectomy and coronectomy in combination with vital pulp treatment based on clinical and radiologic evalutions. The null hypothesis tested in this study was that application of calcium silicate (Biodentine, Septodont, St Maur-des-Fosses, France) after coronectomy had no benefits to reduce above mentioned post-operative complications.

Eligibility Criteria:
Inclusion Criteria:

* - Patients without any systemic disorders
* Close relationship of the lower third molar and inferior alveolar nerve (IAN) on orthopantomography (OPTG) and Cone Beam Computed Tomography (CBCT)
* Pericoronitis around the third molar
* Caries presence or risk for caries development on the distal surface of adjacent second molar
* Follicle enlargement of less than 3 mm around the crown of the mandibular third molar on OPTG
* Teeth with complete apex development

Exclusion Criteria:

* -Presence of active infection (irreversible pulpitis) and/or pathology in the tooth
* In the presence of mobility in tooth
* Teeth with a horizontal position that are closely related to the IAN at the coronal portion
* Teeth undergoing resorption
* Smokers
* Patients who declined to take part in the study.