Evaluation of possible reasons for asymmetries associated with Class II subdivision, Class II division 1 and normal malocclusion

: To evaluate and compare the asymmetries in subjects with two malocclusions that is Class II subdivision, Class II div 1 and normal occlusion.: 90 subjects ranging from 15 to 30 years divided into 3 groups A, B, C. Group A – Class II subdivision, Group B – Class II division I, Group C – Normal Class I occlusion. Angular, linear paired, linear unpaired measurements were calculated based on the Van De Coppell analysis using PA views.: Asymmetry was found in all the three groups where Group A patients showed greater degree of asymmetry near maxillary buttress and piriform aperture areas compared to the three groups. Group C patients showed greater degree of asymmetry in the occlusal plane angle. All the three malocclusions that is Class II div 1 Subdivision, Class II div 1 and Class I malocclusions showed equal amounts of asymmetry. Class II subdivision patients showed greater asymmetry near maxillary buttress area and piriform aperture. Class I malocclusion showed deviation in occlusal plane angle. Along with the lower third involving mandible, maxillary area also can equally show asymmetry in both skeletal and dental parameters.

Morphometric study of nasal bones and piriform apertures in human skulls

The piriform aperture (PA) is the skeletal aperture located in the middle part of the face. There are many variations in morphometric measurements of nasal bones, piriform apertures and their shapes in different population. Objective of present study was to study morphological and morphometric features of nasal bone and piriform aperture. Adult human skulls available from collection of dried skulls were used for study purpose. Skull bones of unknown age and sex were obtained. Height, width of nasal bone, height, upper and lower width of piriform aperture, shapes of nasal bone and piriform aperture were observed. Height, upper width and lower width of piriform aperture were greater in male as compared to female. This difference was not statistically significant for upper width of piriform aperture (p=0.49) and for lower width of piriform aperture (p= 0.65) while the difference in height of piriform aperture was statistically significant. (p <0.0001).Differences in Height and width of nasal bone were not statistically significant among male and female nasal bones. Most common shape of nasal bone observed was Type A followed by Type B and C. Most common shape of piriform aperture was triangular to oval (50.00) in both the gender. Majority finding of the present study are in concordance with Indian population studies while significant differences have been noted in comparison to the morphometric measurements of Turkish, Korean, Brazilian and Anatolian population. These variations might be because of differences in ethnicity.

The skull

The human skull is the skeleton of the head and is considered along with the mandible. It consists of paired bones and unpaired midline bones that contribute to the muscular attachments for mastication and facial expression, a bony foundation for the upper aerodigestive tract and support and housing for the special sensory organs, brain and other structures susceptible to trauma. The skull without the mandible is termed the cranium and consists of the neurocranium and viscerocranium (facial skeleton). The upper third of the skull is principally formed by the frontal bones and exaggerated at the superciliary ridges of the superior orbit and smooth glabella region centrally. The paired maxillary bones form the middle third, creating the circumference of the piriform aperture between, and are separated from the frontal and temporal bones by the zygoma laterally. They house the maxillary sinuses and meet in the midline inferiorly to form the upper jaw and most of the hard palate at the intermaxillary suture.

A safe, stable, and convenient three-dimensional device for high Le Fort I osteotomy

Background Le Fort I osteotomy is a highly effective treatment for skeletal jaw deformities and is commonly performed. High Le Fort I osteotomy is a modified surgical procedure performed for improving the depression of the cheeks by setting the osteotomy higher than the conventional Le Fort I osteotomy. Developments in three-dimensional (3D) technology have popularized the use of 3D printers in various institutions, especially in orthognathic surgeries. In this study, we report a safe and inexpensive method of performing a high Le Fort I osteotomy using a novel 3D device and piezosurgery, which prevent tooth root injury without disturbing the operation field for patients with a short midface and long tooth roots. Results A 17-year-old woman presented with facial asymmetry, mandibular protrusion, a short midface, and long tooth roots. We planned high Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. Prevention of damage to the roots of the teeth and the infraorbital nerve and accurate determination of the posterior osteotomy line were crucial for clinical success. Le Fort I osteotomy using 3D devices has been reported previously but were particularly large in size for this case. Additionally, setting the fixing screw of the device was difficult, because of the risk of damage to the roots of the teeth. Therefore, a different surgical technique, other than the conventional Le Fort I osteotomy and 3D device, was required. The left and right parts of the 3D device were fabricated separately, to prevent any interference in the surgical field. Further, the 3D device was designed to accurately cover the bone surface from the piriform aperture to the infra-zygomatic crest with two fixation points (the anterior nasal spine and the piriform aperture), which ensured stabilization of the 3D device. The device is thin and does not interfere with the surgical field. Safe and accurate surgical performance is possible using this device and piezosurgery. The roots of the teeth and the infraorbital nerve were unharmed during the surgery. Conclusions This device is considerably smaller than conventional devices and is a simple, low-cost, and efficient method for performing accurate high Le Fort I osteotomy.