The stomatognathic system is multifunctional, and is related to mastication, deglutition, phonation, breathing, postural activity, and mimicry. This system and all the associated muscles are directly linked with the hyoid system and cervical spine. This correlational study aimed to relate the convex, the angle Pro Fa, and the angle Pro Max with the location of the hyoid bone in vertical and sagittal direction. The sample consisted of 30 patients, aged between 16 and 20 years, with an average of 18 years and six months that met the following inclusion criteria: absence of previous treatments with equipment fixed or functional, kinesiology, or phonetic. Those patients who suffered cervical skull injuries and disease carriers of systemic diseases were excluded. For this study, cephalograms were performed in the Radiology Department of the FOUNNE under standardized conditions. The mapping of anatomical structures was performed manually and by a single operator. Using multi Max paper, OHP polyester film, and microprobe Faber Castell Multimark 421-S Permanent, measures were taken with Benvenga template and expressed to the half a millimeter and next grade. They were used as references to cephalometric points: Na, Pr, Or, Po, and Pt. It then proceeded to trace levels of Frankfurt, facial plane, and flat Na-A. Facial depth (Prof Fa) angle and angle of the jaw depth (Prof Max) measures were obtained to determine the commitment of the maxilla or the mandible in the skeletal class. This facial convexity was established for the determination of skeletal class and the distance from point A to the facial plane was measured. The subgroups were set according to age-adjusted values of Pro Max and Pro Fa angles, distributed as follows: Group III s1 consisted of 14 patients, and s2 consisted of 16 patients. The position of the hyoid bone was determined in vertical and horizontal direction for which was measured the height of the hydroid triangle (H-H1) and the distance of the hyoid point to vertical pterygoid (H-PTV), respectively. The association of convex-PTV variables approached significance with p value = 0.06, while Pro Fa association with H-PTV was statistically significant in both s1 and s2. As for Pro Max, it was statistically significant only in s1. These results would indicate that the position of the bone in the anteroposterior direction was influenced by the traction of the suprahydroid musculature that tries to accompany the mandibular function and position.
(Rev Esp Ortod. 2017;47(2):090-097)