PubMed · 11307419
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D Nordstrom. 2000. Craniometer/Aqualizer techniques.. https://pubmed.ncbi.nlm.nih.gov/11307419/
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The purpose of this study was to identify the potential projection errors of posteroanterior cephalometric radiographs due to head rotation in the vertical Z-axis. For this investigation, 20 human dry skull samples with permanent dentition were collected from the Department of Anatomy in the College of Medicine, Chosun University, Korea. They had no gross asymmetries and were well preserved. Each dry skull was rotated from 0 degrees to +/- 10 degrees at 1 degrees intervals. A vertical axis, the Z-axis, was used as a rotational axis for the exposure of 420 posteroanterior cephalometric radiographs. Most of the abscissa values of each landmark showed statistically significant differences in the head rotation from each rotational angle (P < .05), whereas the ordinate values were almost the same in all rotational angles regardless of the head rotation. The abscissa values of each landmark anterior to the vertical rotational axis displaced in the same direction as the head rotation, whereas those of other landmarks posterior to the vertical rotational axis displaced in the opposite direction. The mean differences of the abscissa values, per 1 degrees of head rotation, were larger as the landmark was located further anteroposteriorly from the vertical rotational axis and smaller as the landmark was located nearer the vertical rotational axis. In view of the projection error, a posteroanterior cephalometric radiograph is a more valuable diagnostic tool when it is exposed with no head rotation about the vertical Z-axis.
This study was conducted to examine the effect of treatment with a maxillary protraction appliance on the development of the craniofacial structures and upper-airway dimensions. A total of 25 patients (mean age: 9.8 years) with Class III malocclusions were evaluated by the use of lateral cephalograms. A significant increase in maxillary forward growth, inhibition of mandibular forward growth, and clockwise rotation of the mandible were observed. The maxillary incisors were significantly proclined and the mandibular incisors significantly retroclined. A multiple-regression analysis revealed that maxillary growth had a significant positive effect on the superior upper-airway dimension. These findings indicate that the superior upper-airway dimension can be altered during maxillary protraction.
OBJECTIVE: To define parameters that enable the objective diagnosis of anomalies of the position and/or size of the fetal mandible in utero. DESIGN: Fetuses at 18-28 gestational weeks were examined by two- and three-dimensional ultrasound. The study included normal fetuses and fetuses with syndromes associated with known mandible pathology: Pierre Robin sequence or complex (n = 8); hemifacial microsomia (Treacher-Collins syndrome, n = 3); postaxial acrofacial dysostosis (n = 1). Fetuses with Down syndrome (n = 8) and cleft lip and palate without Pierre Robin sequence or complex (n = 18) were also studied. Retrognathia was assessed through the measurement of the inferior facial angle, defined on a mid-sagittal view, by the crossing of: 1) the line orthogonal to the vertical part of the forehead at the level of the synostosis of the nasal bones (reference line); 2) the line joining the tip of the mentum and the anterior border of the more protruding lip (profile line). Micrognathia was assessed through the calculation of the mandible width/maxilla width ratio on axial views obtained at the alveolar level. Mandible and maxilla widths were measured 10 mm posteriorly to the anterior osteous border. RESULTS: In normal fetuses, the inferior facial angle was constant over the time span studied. The mean (standard deviation) value of the inferior facial angle was 65.5 (8.13) degree. Consequently, an inferior facial angle value below 49.2 degree (mean - 2 standard deviations) defined retrognathism. All the fetuses with syndromes associated with mandible pathology had inferior facial angle values below the cut-off value. Using 49.2 degree or the rounded-up value of 50 degree as a cut-off point, the inferior facial angle had a sensitivity of 1.0, a specificity of 0.989, a positive predictive value of 0.750 and a negative predictive value of 1.0 to predict retrognathia. In normal fetuses, the mandible width/maxilla width ratio was constant over the time interval studied. The mean (standard deviation) value was 1.017 (0.116). Consequently, a mandible width/maxilla width ratio < 0.785 defined micrognathism. Mandible width/maxilla width ratio values were below this cut-off point in eight and in the normal range in four fetuses with syndromes associated with mandible pathology. CONCLUSIONS: Retrognathia and micrognathia are conditions that can be separately assessed. The use of inferior facial angle and mandible width/maxilla width ratio should help sonographic recognition and characterization of fetal retrognathic and micrognathic mandibles in utero.