X-ray beam angulation can compromise 2-dimensional diagnosis of interradicular space for mini-implants

• Published in: American journal of orthodontics and dentofacial orthopedics Vol. 156; no. 5; pp. 593 - 602
• Main Authors: Barros, Sérgio Estelita, Abella, Matilde, Janson, Guilherme, Chiqueto, Kelly
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2019
• Subjects: Alveolar Process; Cone-Beam Computed Tomography; Dental Implants; Dentistry; Humans; Tooth Root - diagnostic imaging
• ISSN: 0889-5406; 1097-6752
• DOI: 10.1016/j.ajodo.2018.11.012

The aim of this research was to evaluate the influence of x-ray projection geometry on interradicular space of the posterior maxillary arch. Cone-beam computed tomography (CBCT) scans of 32 patients (16.85 ± 4.93 years) who met the selection criteria were enrolled. One hundred ninety-two interradicular sites of the posterior maxillary arch were evaluated. Before measurements, each side of the maxillary arch was orientated in all 3 planes of space to obtain CBCT synthesized periapical radiographs with 0° projection geometry (orthogonal x-ray beam—orthogonal X-ray angulation [OX]). Standardized CBCT axial rotations (10°, 20°, –10°, and –20°) were used to simulate periapical radiographs taken with mesial and distal angulation of the x-ray beam (mesial x-ray angulation [MX] and distal x-ray angulation [DX]). Interradicular space widths were measured on OX, MX, and DX CBCT synthesized periapical radiographs. Measurements were performed parallel to the occlusal plane at 3 mm and 6 mm apical to the midpoint of the alveolar crest. Interradicular distances were statistically compared (P <0.05). Interradicular distances measured on MX and DX CBCT synthesized periapical radiographs were significantly smaller than those measured on OX. Interradicular distance was significantly correlated with the horizontal angulation of the x-ray beam. X-ray projection angle was the most influential variable on interradicular distance. About 30% reduction in interradicular space was observed for every 10° of deviation from orthogonal x-ray. Two-dimensional radiographs obtained away from the 0° projection geometry can reduce the actual interradicular space for mini-implants, inducing misdiagnosis. •Interradicular space width was influenced by x-ray projection angle.•High correlation was observed between the interradicular space and horizontal angle of the x-ray beam.•About 30% reduction in interradicular space was observed for each 10° of deviation from orthogonal x-ray projection.•X-ray projection geometry can mask the actual septum width, inducing misdiagnosis.