Abstract
ABSTRACT Objective The objective of this study was to 1) evaluate the reproducibility of natural head position (NHP) in different professional groups; 2) compare three cephalometric methods of estimating head position to the established natural head position and 3) investigate the applicability of a new method to estimated head position using a Centroid method. Methods The sample consisted of 105 individual cephalometric tracings and photographs. For the first evaluation, copies of the lateral photographs were reproduced for each patient and 3 professionals with different expertise (experienced orthodontists, orthodontic students and orthognatic surgeon) were instructed to position the photographs in NHP. Later, 3 different methods to obtain NHP were assessed: 1) the Frankfort Horizontal Plane (FRANK), 2) Sella-Nasion 7º Line (SN7) and 3) proposed Horizontal Reference Line based on Centroid. Angles formed by the evaluated planes/lines and True Vertical Line obtained were measured. Gender and skeletal discrepancy were considered. Results The results showed a significant difference between NHP obtained from orthodontists and surgeons compared to students (p<0.0001). Also results showed no effect of skeletal classification and gender did on measurement (p>0.05). Both SN minus 7º and FRANK methods showed a high variability (p < 0,01) compared to Centroid method. Conclusion NHP may be affected by the professional experience. The proposed horizontal line based on Centroid is a valid method for estimating head position, thus, may be indicated to use as a diagnostic tool in Orthodontics and Orthognatic Surgery.
Highlights
IntroductionIn order to determine skeletal maxillomandibular relationship by cephalometric analysis, two methods are most commonly used to guide head position, either using intracranial or extracranial references [2,3]
Cephalometric analyses have become indispensable in clinical Orthodontics and orthognatic surgery in order to obtain a proper diagnosis, treatment planning, therapy monitoring and evaluation of treatment results, as well as, craniofacial growth follow-up [1].In order to determine skeletal maxillomandibular relationship by cephalometric analysis, two methods are most commonly used to guide head position, either using intracranial or extracranial references [2,3]
The sample consisted of lateral photographs and cephalometric radiographs of 212 subjects, age varying from 12 to 48 years old divided in 4 groups: Group 1 consisted in 60 skeletal Class I patients, Group 2 in 79 skeletal Class II and III patients and Group 3 in 73 patients presenting vertical discrepancies
Summary
In order to determine skeletal maxillomandibular relationship by cephalometric analysis, two methods are most commonly used to guide head position, either using intracranial or extracranial references [2,3]. Intracranial reference, such as the Sella-Nasion line [1] and Frankfort horizontal [4] are widely used. Landmarks used to determine these intracranial references may not be stable and may change continuously during growth, leading to greater variability among individuals These lines/planes are inherently unreliable and likely to mislead orthodontic diagnosis and treatment planning [3]. A recent study has shown that skeletal cephalometrics may lead to a different diagnosis of patient’s facial characteristics [5]
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