CBCT assessment of posterior cranial base and surrounding structures in orthodontically treated adolescents.

OBJECTIVE: Understanding craniofacial growth and development is important for accurate diagnosis, treatment planning and post-treatment evaluation of orthodontic cases. Paramount to this is knowledge of the cranial base growth and development, since it is the foundation upon which the remaining facial structures develop. The purpose of this study was to analyse different anatomical structures in the posterior cranial base and determine its changes during the adolescent years (13-15 year of age) using CBCT. MATERIALS AND METHODS: Sixty CBCT images of the adolescent population that received orthodontic treatment at two time-points (mean age T1: 13.1 years/T2: 14.6years) were used to assess growth related dimensional changes using 33 selected landmarks. Inter-rater, intra-rater and accuracy of 33 selected landmarks in the posterior cranial base and surrounding area were then evaluated via three-dimensional (3D) cone-beam computed tomography (CBCT). Linear differences were then calculated among the different landmarks to determine the changes present in the sample. RESULTS: The selected landmarks in the posterior cranial base and surrounding area were found to be reliably and accurately located in 3D. Over the growth period studied (17.5months), minor statistically significant changes occurred, but they were deemed clinically irrelevant. CONCLUSIONS: The studied landmarks in the posterior cranial base and surrounding area showed minor clinically insignificant changes over the study period. The observed changes could be attributed to measurement error. The posterior cranial base is deemed to be stable in all three dimensions of study during the adolescent growth period studied.

Reliability of different three-dimensional cephalometric landmarks in cone-beam computed tomography : A systematic review.

OBJECTIVES: Conventional two-dimensional (2D) cephalometric radiography is an integral part of orthodontic patient diagnosis and treatment planning. One must be mindful of its limitations as it indeed is a 2D representation of a vaster three-dimensional (3D) object. Issues with projection errors, landmark identification, and measurement inaccuracies impose significant limitations, which may now be overcome with the advent of cone-beam computed tomography (CBCT). A systematic review of the reliability of different 3D cephalometric landmarks in CBCT imaging was conducted. MATERIALS AND METHODS: Electronic database searches were administered until October 2017 using PubMed, MEDLINE via OvidSP, EBMR and EMBASE via OvidSP, Scopus, and Web of Science. Google Scholar was used as an adjunctive search tool. RESULTS: Thirteen articles considering CBCT scans of human subjects from preexisting data sets were selected and reviewed. Most of the studies had methodological limitations and were of moderate quality. Because of their heterogeneity, key data from each could not be combined and were reported qualitatively. Overall, in 3D, midsagittal plane landmarks demonstrated greater reliability compared with bilateral landmarks. A minimum number of dental landmarks were reported, although most were recommended for use. CONCLUSIONS: Further research is required to evaluate the reliability of 3D cephalometric landmarks when evaluating 3D craniofacial complexes.

Posterior cranial base natural growth and development: A systematic review.

OBJECTIVE: To provide a synthesis of the published studies evaluating the natural growth and development of the human posterior cranial base (S-Ba). MATERIALS AND METHODS: The search was performed on MEDLINE, Embase, PubMed, and all EBM Reviews electronic databases. In addition, reference lists of the included studies were hand-searched. Articles were included if they analyzed posterior cranial-base growth in humans specifically. Study selection, data extraction, and risk of bias assessment were completed in duplicate. A meta-analysis was not justified. RESULTS: Finally, 23 published studies were selected: 5 cross-sectional and 18 cohort studies. Articles were published between 1955 and 2015, and all were published in English. The sample sizes varied between 20 and 397 individuals and consisted of craniofacial measurements from either living or deceased human skulls. Validity of the measurements was not determined in any of the studies, while six papers reported some form of reliability assessment. All the articles included multiple time points within the same population or data from multiple age groups. Growth of S-Ba was generally agreed to be from spheno-occipital synchondrosis growth. Basion displaced downward and backward and sella turcica moved downward and backward during craniofacial growth. Timing of cessation of S-Ba growth was not conclusive due to limited identified evidence. CONCLUSIONS: Current evidence suggests that S-Ba is not totally stable, as its dimensions change throughout craniofacial growth and a minor dimensional change is observed even in late adulthood.

Diagnostic methods for assessing maxillary skeletal and dental transverse deficiencies: A systematic review.

OBJECTIVE: To evaluate the accuracy and reliability of the diagnostic tools available for assessing maxillary transverse deficiencies. METHODS: An electronic search of three databases was performed from their date of establishment to April 2015, with manual searching of reference lists of relevant articles. Articles were considered for inclusion if they reported the accuracy or reliability of a diagnostic method or evaluation technique for maxillary transverse dimensions in mixed or permanent dentitions. Risk of bias was assessed in the included articles, using the Quality Assessment of Diagnostic Accuracy Studies tool-2. RESULTS: Nine articles were selected. The studies were heterogeneous, with moderate to low methodological quality, and all had a high risk of bias. Four suggested that the use of arch width prediction indices with dental cast measurements is unreliable for use in diagnosis. Frontal cephalograms derived from cone-beam computed tomography (CBCT) images were reportedly more reliable for assessing intermaxillary transverse discrepancies than posteroanterior cephalograms. Two studies proposed new three-dimensional transverse analyses with CBCT images that were reportedly reliable, but have not been validated for clinical sensitivity or specificity. No studies reported sensitivity, specificity, positive or negative predictive values or likelihood ratios, or ROC curves of the methods for the diagnosis of transverse deficiencies. CONCLUSIONS: Current evidence does not enable solid conclusions to be drawn, owing to a lack of reliable high quality diagnostic studies evaluating maxillary transverse deficiencies. CBCT images are reportedly more reliable for diagnosis, but further validation is required to confirm CBCT's accuracy and diagnostic superiority.