[Facial volumes and vertical facial type: a three dimensional comparative study]

Three-dimensional evaluation of the nasomaxillary complex before and following rapid maxillary expansion compared to normal subjects

Objectives:

The objectives of the study were to evaluate the nasomaxillary complex (NMC) measurements before and following rapid maxillary expansion (RME) compared to normal subjects.

Materials and Methods:

Thirty consecutive patients (14 males and 16 females) with a mean age of 9.5 ± 1.8 years for males and of 11.8 ± 1.7 years for females, who underwent RME to correct their posterior unilateral or bilateral crossbite, were selected. Computed tomography (CT) scans done before treatment (BT) formed the Group BT and those after treatment constituted the Group AT. An untreated normal sample (Group NC) presenting a normal transverse occlusion and needing a cone beam CT for other purposes was formed by 30 subjects (14 males and 16 females) with a mean age of 10 ± 0.9 years for males and of 11.6 ± 1.0 years for females. The CT scans were compared between both groups BT and AT with Group NC and measurements were performed on scanned images. The mean differences between measurements were compared using the t-test (α = 0.05).

Results:

No significant differences in volumetric measurements representing the NMC were found between groups BT and NC. By comparing Group AT to NC, we found that all volumetric variables displayed statistically significant differences with an increase of those of Group AT. Linear transverse variables were increased in Group NC compared to Group BT and their differences were statistically significant. However, the same variables were larger in Group AT compared to Group NC.

Conclusion:

RME produces an increase of the NMC dimensions compared to normal controls, which supports the principle of overcorrection, needed to compensate the post-treatment relapse.

Evaluation of upper airway volume and craniofacial volumetric structures in obstructive sleep apnoea adults: A descriptive CBCT study

OBJECTIVE

The aim of this investigation was to assess, with a descriptive three-dimensional evaluation, the volume of upper airway (UAWV) and the volume of craniofacial structures in adult patients suffering from obstructive sleep apnoea (OSA) and compare them to the corresponding findings in adults with no sleep disorders.

MATERIALS AND METHODS

The sample consisted of 54 adult males, 27 suffering from OSA diagnosed by means of the Apnoea Hypopnea Index and 27 with no history of sleep disorders. All subjects had a cone beam computerized tomography scan performed with the same head position. UAWV was assessed with the Amira® software, and craniofacial volumes by means of a specially developed data-processing program, which allowed the construction of tetrahedrons using anatomical landmarks. Assessed volumes were naso-maxillary, cranium upper anterior, oral cavity, post-oral cavity, hyoid to mandible, and post-hyoid. SPSS (version 19.0) was used for the statistical analysis. The Levene's test for Equality of Variance, the t-test for Equality of Means and the Mann-Whitney test were used to evaluate the variables. The level of significance was set at P ≤ 0.05.

RESULTS

The mean value of UAWV was smaller in the OSA group. The post-hyoid volume, the calculated posterior volume, and the ratio of posterior to total volume showed differences between the groups.

CONCLUSIONS

Craniofacial structures did not show significant differences between the groups, but in the OSA group the posterior space released for upper airway was significantly bigger and UAWV was significantly smaller.

Differences in the mandibular premolar positions in Angle Class I subjects with different vertical facial types: A cone-beam computed tomography study

Objective

To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment.

Methods

Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured.

Results

The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type.

Conclusions

There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

Three-dimensional changes of the naso-maxillary complex following rapid maxillary expansion

OBJECTIVE

To assess the volumetric changes and the maxillary response of the naso-maxillary complex (NMC) following rapid maxillary expansion (RME).

MATERIALS AND METHODS

Thirty consecutive patients (14 males and 16 females) with a mean age at first observation of 9.5 ± 1.8 years for males and of 11.8 ± 1.7 years for females, presenting a posterior unilateral or bilateral crossbite and requiring RME, were selected for the study. Each patient underwent expansion to correct the transverse occlusal relationships. Computed tomography scans were taken before RME (T1) and at the end of the active expansion phase (T2). Measurements were performed on scanned images. The Kolmogorov-Smirnov test was performed; the mean differences between measurements at T1 and T2 were compared using the t-test (α = .05).

RESULTS

All volumetric, maxillary, transverse skeletal anterior and posterior variables as well as all dental anterior and posterior linear and angular variables representing the NMC displayed statistically highly significant increases after RME (P < .001).

CONCLUSIONS

After RME the total volume of the NMC increased by 12%, the nasal volume by 17%, and the maxillary volume by 10.6%. The maxillary and the nasal contributions represented 69.75% and 30.25%, respectively.

[Digitized impressions: myth and daily reality]

The digitizing of impressions, or models made from them, opens, in the same way that digitized 3D X-rays did, new horizons for practitioners in the management for their offices, in their interactions with patients, and in their shared work with dental laboratories. Mastery of digitized models improves the efficiency and reinforces the quality of dental treatment through the new perspectives digital analyses provide. Finally the maintenance of records is greatly simplified in far less space while still respecting all pertinent legal requirements, thus assuring total suitability for all current regulations.