23 research outputs found
Tomographic evaluation of the temporomandibular joint in malocclusion subjects: condylar morphology and position
Do skeletal cephalometric characteristics correlate with condylar volume, surface and shape? A 3D analysis
Condylar volume and surface in Caucasian young adult subjects
<p>Abstract</p> <p>Background</p> <p>There have been no quantitative standards for volumetric and surface measurements of the mandibular condyle in Caucasian population. However, the recently developed cone-beam computed tomography (CBCT) system allows measurement of these parameters with high accuracy.</p> <p>Methods</p> <p>CBCT was used to measure the condylar volume, surface and the volume to surface ratio, called the Morphometric Index (MI), of 300 temporo-mandibular joints (TMJ) in 150 Caucasian young adult subjects, with varied malocclusions, without pain or dysfunction of TMJs.</p> <p>Results</p> <p>The condylar volume was 691.26 ± 54.52 mm<sup>3 </sup>in males and 669.65 ± 58.80 mm<sup>3 </sup>in, and was significantly higher (<it>p</it>< 0.001) in the males. The same was observed for the condylar surface, although without statistical significance (406.02 ± 55.22 mm<sup>2 </sup>in males and 394.77 ± 60.73 mm<sup>2 </sup>in females).</p> <p>Furthermore, the condylar volume (693.61 ± 62.82 mm<sup>3 </sup>) in the right TMJ was significantly higher than in the left (666.99 ± 48.67 mm<sup>3</sup>, <it>p </it>< 0.001) as was the condylar surface (411.24 ± 57.99 mm<sup>2 </sup>in the right TMJ and 389.41 ± 56.63 mm<sup>2 </sup>in the left TMJ; <it>t </it>= 3.29; <it>p </it>< 0.01). The MI is 1.72 ± 0.17 for the whole sample, with no significant difference between males and females or the right and left sides.</p> <p>Conclusion</p> <p>These data from temporomandibular joints of patients without pain or clinical dysfunction might serve as examples of normal TMJ's in the general population not seeking orthodontic care.</p
Relationship between articular eminence inclination and alterations of the mandibular condyle: a CBCT study
The postglenoid tubercle: prevalence and growth
Aim: To quantify the prevalence and growth of the postglenoid tubercle
in a skull sample and in children. Material: a) ninety skulls ranging in
age from between 2 years and adulthood, b) sixtyfour corrected lateral
tomograms of left and right temporomandibular joints of 32 boys and
girls. Their age range was between 9 and 11 years.
Method: Impressions of the temporal fossae of the skull material were
taken with a silicone type impression material, using a face-bow for
leveling the base of the impression parallel to the FH plane. Each
impression was divided into two halves along a paramedian plane from the
tip of the postglenoid tubercle through the middle of the articular
eminence and the surface was photocopied to a 200% scale. Height was
measured with an electronic caliper. The presence or absence of a
postglenoid tubercle was established on the corrected tomograms.
Findings: Seventy-nine percent of the skulls had a postglenoid tubercle.
It steadily enlarged and reached almost its final dimension by the age
of 13 years. On corrected tomograms, 66% of the children showed a
postglenoid tubercle.
Conclusions: a) the postglenoid tubercle exists in a high percentage of
human temporomandibular joints b) growth is almost completed by the age
of 13, and c) there exists a right-left symmetry
Intermaxillary forces during activator treatment
The mode of action of the activator appliance is still unclear. Apart
from a possible mandibular growth enhancing effect, some investigators
believe that orthopedic forces may be applied to the maxilla,
contributing to Class II correction by inhibition of maxillary growth.
In addition, orthodontic forces may arise that produce dentoalveolar
changes. The purpose of this study was to measure the magnitude of
anteroposterior intermaxillary forces during wear of the activator
appliance. Ten consecutive patients with Class II dental and skeletal
relationships were treated with a modified activator appliance. The
appliance had maxillary and mandibular segments that could be detached
from each other during the measuring session, A force transducer was
placed at the anterior part of the maxillary segment, and the
anteroposterior force exerted by the mandibular segment was measured.
Measurements were taken in the upright and reclined position at every
patient visit for a period of 6 months. Results indicated that
intermaxillary forces were generally in the orthodontic range (median
values of 100 gf at the upright position and 123 gf at the reclined
position). A wide variation in force levels was noted, both between
patients and for the same patient during the experimental period. No
statistically significant change in force levels was observed during the
6 month period and no difference was noted between upright and reclined
posture