Combined photographic and ultrasonographic measurement of the ANB angle: a pilot study

Oral Radiol (2017) 33:212–218 DOI 10.1007/s11282-017-0275-y ORIGINAL ARTICLE Combined photographic and ultrasonographic measurement of the ANB angle: a pilot study Alberto Di Blasio1 · Chiara Di Blasio2 · Giuseppe Pedrazzi4 · Diana Cassi3 · Marisabel Magnifico1 · Edoardo Manfredi1 · Mauro Gandolfini1 Received: 1 August 2016 / Accepted: 23 November 2016 / Published online: 21 March 2017 © The Author(s) 2017. This article is an open access publication Abstract Objective This study was performed to evaluate the feasibility of noninvasive measurement of the ANB angle using photographic and ultrasonographic methods. Methods Twenty consecutive orthodontic patients were evaluated. The ANB angle and soft tissue thickness covering the N, A, and B cephalometric points were measured by lateral teleradiography; these measurements were made by two expert operators. The soft tissue thickness covering the N, A, and B cephalometric points was measured by ultrasonography; these measurements were also made by two expert operators. On a 1:1 photographic profile print on which the ultrasonographic points were marked, the ANB ultrasonographic angle was measured. The following comparisons were considered: averaged and single measurements of N, A, and B points by first versus second ultrasonographer; averaged and single ultrasonographic versus radiographic soft tissue thickness covering the N, A, B points; and averaged and single ultrasonographic versus radiographic measurements of ANB angle. Results High correlation and concordance of the averaged and single measurements, but no significant difference, was found between the two ultrasonographers. No statistically * Chiara Di Blasio 1 S.Bi.Bi.T. Department, University of Parma (Italy), Via Gramsci 14, 43126 Parma, Italy 2 Head and Neck Department, University of Parma (Italy), Via Gramsci 14, 43126 Parma, Italy 3 Doctoral School in Life and Health Science, University of Parma (Italy), Via Gramsci 14, 43126 Parma, Italy 4 Neuroscience Department, University of Parma (Italy), Via Volturno 39, 43125 Parma, Italy 13 Vol:.(1234567890) significant difference was found between the two methods for measuring averaged soft tissue thickness, but a 20% difference was found for the single measurements. High correlation and concordance between the ultrasonographic and radiographic measurements, but no significant difference, was found between the single and averaged ANB angle measurements. Conclusion Ultrasonography seems to be a noninvasive and reliable technique for measurement of the ANB angle and may replace radiographic measurement in some cases. Keywords Orthodontics · Cephalometry · Ultrasonography · Dimensional measurement accuracy · Radiation protection Introduction Although some controversy regarding the correct use of lateral cephalometric radiographs is still present in orthodontic textbooks, cephalometric analysis is the basis of every type of orthodontic treatment planning [1–3]. For most orthodontists, cephalometric radiography is the standard imaging technique and an invaluable means of obtaining diagnostic information for the management of malocclusion and skeletal disharmony. Cephalometric radiographs, introduced to the field of orthodontics by Broadbent [4, 5] in 1931 in the US, were soon employed by early investigators [6–9] to assess the skeletal relations of the facial bones and the long-axis inclination of the anterior teeth. In 1953, Steiner [10–12] proposed his original analysis containing a description of the ANB angle. This angle relates the anterior limit of the maxillary bone (A point) and mandibular bone (B point) with the anterior limit of the nasofrontal suture (N point). The ANB angle measures the relative Oral Radiol (2017) 33:212–218 anteroposterior position between the maxilla and mandible. In normal individuals, the ANB angle is 2° ± 2° at the end of growth. Since its first description in 1953, the ANB angle has remained one of the most frequently measured cephalometric data to assess the maxillomandibular relations, even in complex cases involving orthodontic or orthognathic surgery [13–16]. From 1950 to 1970, the progress in orthodontic cephalometry was logarithmic, and a large number of analyses were proposed. The golden age of cephalometry ended in 1970 with the complex analysis proposed by Delaire [17–19] and Delaire et al. [20]. Today, orthodontists are able to measure the proportions of the human face with a high degree of precision using a very wide range of different cephalometric analyses. Not every orthodontist uses the same analysis in clinical practice; each orthodontist selects the technique that best meets his or her needs and expectations. Despite these differences, all clinicians agree that cephalometry is an unavoidable step in orthodontic treatment planning. However, concerns regarding radiographic exposure, particularly in growing individuals, may limit its use [21]. This is especially problematic because the use of longitudinal radiographs to assess a patient’s growth and therapeutic outcome is still a common practice [22]. A new radiographic technique may only be advised when its outcome results in a different treatment decision. Other clinical analysis techniques such as anthropometry may be used to avoid frequent radiographic exposure and may be useful in further understanding the patient’s structure. Using anthropometrics, the orthodontist directly examines the patient’s face or facial photographs to understand the deformity and appreciate the progressive effect of the therapy [23]. Several authors have proposed anthropometric evaluations, sometimes creating a very complex analysis, as in Arnett’s soft tissue cephalometric analysis [24–28]. Unfortunately, this clinic facial evaluation cannot fully replace cephalometry because skeletal orthodontic therapy is indicated in growing patients while facial anthropometry has only been well studied in adults, and not every face presents the same soft tissues thickness covering important points such as the N, A, and B points. Another way to perform noninvasive evaluation of the facial structure, the DigiGraph work station, was described in 1990 by Chaconas et al. [29, 30], in 1995 by Prawat et al. [31], and in 1999 by Tsang and Cooke [32]. Despite the good reliability of this method among 11 sonic cephalometric measurements, 26 values demonstrated a weak correlation with the relative radiographic values [33]. Unfortunately, the patient’s actual clinical skeletal situation and the precise effect of therapy are still only evaluable by cephalometry. Every cephalometric analysis employs several anatomical skeletal points; some of these points are deep within the skull, such as the sella (S) or basion (Ba) points, and some are on the surface of the bone near the skin, such as the 213 N, A, or B points. Deep points are often used to identify reference planes such as the ideal horizontal plane, despite the fact that the ability to accuratel (...truncated)