Assessing mandibular body changes in growing subjects: a comparison of CBCT and reconstructed lateral cephalogram measurements

Abstract

the aim of this study is to compare cone-beam computed tomography (cBct) and bi-dimensional reconstructed lateral cephalograms (RLcs) in assessing mandibular body length and growth and to evaluate how mandibular reshaping influences the error in measuring mandibular body growth in bi-dimensional radiographs. Twenty-five patients with two CBCT scans taken at a mean distance of 2.21 ± 0.5 years were selected. The following measurements were performed: right and left mandibular body length at each point in time, mandibular growth, inter-gonial distance and mandibular symphyseal angle. From each CBCT, an RLC was obtained, and mandibular body length and growth were measured. Data analysis revealed a statistically and clinically significant difference in CBCT and RLC regarding the mandibular length of each patient at each point in time. However, mandibular growth was almost identical. A linear regression was performed to predict growth distortion between RLCs and CBCT depending on the ratio between transverse and sagittal mandibular growth. The expected maximum and minimum distortion, however, appeared not to be significant. In fact, a second linear regression model and a Bland-Altman test revealed a strong correlation between measurements of average mandibular body growth by CBCT and RLCs. As the same distortion occurs in the first and second RLCs, bi-dimensional radiographs remain the method of choice in evaluating mandibular body growth. Mandibular length is an important indicator of therapeutic success. In the literature, this variable has been measured using different radiographic techniques. In 1931, Broadbent 1 described a method to study facial growth by lateral teleradiographs. Despite some drawbacks, such as variable magnification, different grades of distortion, and limited repeatability of head position, the technique of superimposing cephalometric tracings taken over time has been accepted for clinical and research purposes in orthodontics 2. Several aspects of the growth of the maxillofacial complex have been studied so far, such as the direction and intensity of growth in different cohorts of patients with a sequence of cephalometric radiographs 2-4. The growth of the maxillofacial complex is steep during the first 4 years of life 5 , and it becomes flatter until puberty, when it becomes steeper again during the adolescent growth spurt 6. The timing of maxillofacial growth differs between boys and girls; its onset and peak occur at ages 12 and 14 years, respectively, in boys and 9.5 and 11.5 years, respectively, in girls 6-8. Modifications that occur in the human mandible during growth were first studied by Bjork 9,10 and Enlow 11,12. Small pointed pins were implanted into the mandible and used as a fixed reference for evaluating bone growth. While useful baseline information was provided by this and subsequent studies 2,4 , the data were limited to two-dimensional (2D) measurements.

Increased Risk of Temporomandibular Joint Disorder in Patients with Rheumatoid Arthritis: A Longitudinal Follow-Up Study

“…TMJ pain could have a negative effect on the normal activities and quality of life in patients with RA [45,46]. These findings were similar to those of previous studies, in which degenerative bone changes were observed on radiographic or magnetic resonance imaging, in patients with TMJ and RA (MRI) [47][48][49]. Meanwhile, Uchiyama et al demonstrated that the incidence of bony deformation in the mandibular condyle was not related to the duration of RA or changes in the other joints [50].…”

Limited Mandibular Movements as a Consequence of Unilateral or Asymmetrical Temporomandibular Joint Involvement in Juvenile Idiopathic Arthritis Patients

“…It should be emphasized, however, that CBCT examination allowed the precise analysis of condylar morphology, but it did not enable the diagnosis of soft tissue inflammation. The abnormalities visible in the radiological examinations result from irregularities within the bone tissue and indicate the chronic nature of the disease [ 26 , 27 ]. The gold standard in TMJ diagnostics in JIA patients is MRI, with which it is possible to visualize not only chronic deformations resulting from a long-term degenerative process but also active inflammation of TMJ, i.e., synovitis [ 27 , 28 , 29 , 30 ].…”

“…TMJ arthritis may cause damage to articular structures in addition to affecting the mandibular growth center, located below the thin cartilage layer of the articular head of the condylar process, thus contributing to the inhibition of mandibular growth [ 4 , 27 ]. The growth center is responsible for the growth of the entire mandible (body, ramus, and angle).…”

“…Subsequently, as a result of bone accumulation on the base of the mandibular body, the mandible grows downwards. At the same time, the ramus lengthens due to the bone growth within the condylar process [ 27 , 29 , 31 ]. Unilateral TMJ involvement (or a more advanced form in one of the joints) may cause uneven growth of the right and left side of the jaw and cause ramus shortening as well as reducing the size mandibular body on the damaged side [ 5 , 28 ].…”

“…Genetically determined malocclusion may contribute to a more pronounced deformation of the lower face in JIA patients. Moreover, the degree of deformation is closely related to the growth potential of the mandible and depends on the child’s age at the onset of the disease [ 4 , 27 ]. The most intensive growth phase of the mandible takes place up until six years of age.…”