Anatomical Prerequisites for the Placement of Transnasal Implants: A Cone-Beam Computed Tomography Study of 200 Consecutive Patients: A cross-sectional Study

ABSTRACT

Background

Rehabilitation of patients with severe atrophy of the anterior maxilla is a complex clinical task. Transnasal implants are considered an alternative to the anterior pair of zygomatic implants using the quad-zygoma protocol, allowing a reduction in the risk of complications and avoiding extensive bone grafting. However, the anatomical variability of the attachment area of the inferior nasal concha to the lateral nasal wall (“point Z”) and clear criteria for patient selection for this technique remain insufficiently studied.

Aim

To study the anatomical structure of point Z, its location and size, and to classify patients according to the volume of bone tissue in this area in order to prevent complications during transnasal implantation. METHODS:A cross-sectional analysis of CBCT scans of 200 patients (68 males, 132 females) aged 25 to 86 years was performed. Bone thickness in the area of attachment of the inferior nasal concha, the diameter of the nasolacrimal canal, and its distance from the lateral wall of the maxillary sinus were measured. Patients were divided into three groups according to bone thickness: 3 mm (insufficient), ≥3 mm, and ≥4.5 mm. RESULTS:The mean bone thickness at point Z was 3.77 mm (4.28 mm in males, 3.51 mm in females). Bone volume sufficient for transnasal implant placement (≥3 mm) was found in 62% of cases, of which in 36.5% the thickness exceeded 4.5 mm. The mean diameter of the nasolacrimal canal was 6.275 mm, and the mean distance from the canal to the lateral wall of the sinus was 5.70 mm. CONCLUSION:Anatomical conditions for transnasal implantation are present in the majority of patients (62%), and in men they are significantly more favorable (bone volume 22% greater than in women). The obtained quantitative data can be used for preoperative planning and patient selection. Prospective studies are required for the final implementation of the technique in clinical practice.