Comparison of osseous healing after sagittal split ramus osteotomy and intraoral vertical ramus osteotomy

The sagittal split ramus osteotomy (SSRO) is generally associated with greater postoperative stability than the intraoral vertical ramus osteotomy (IVRO); however, it entails a risk of inferior alveolar nerve damage. In contrast, IVRO has the disadvantages of slow postoperative osseous healing and projection of the antegonial notch, but inferior alveolar nerve damage is believed to be less likely. The purposes of this study were to compare the osseous healing processes associated with SSRO and IVRO and to investigate changes in mandibular width after IVRO in 29 patients undergoing mandibular setback. On computed tomography images, osseous healing was similar in patients undergoing SSRO and IVRO at 1year after surgery. Projection of the antegonial notch occurred after IVRO, but returned to the preoperative state within 1year. The results of the study indicate that IVRO is equivalent to SSRO with regard to both bone healing and morphological recovery of the mandible.

Predictors of obstructive sleep apnoea-hypopnea severity and oral appliance therapy efficacy by using lateral cephalometric analysis

Obstructive sleep apnoea-hypopnea (OSAH) is a common disorder characterised by repetitive complete or partial closure of the upper airway during sleep, which results in sleep fragmentation and oxygen desaturation. There is growing interest in the use of oral appliances (OAs) to treat OSAH. The purpose of this study was to clarify the cephalometric factors that are associated with OSAH severity and that predict the outcome of OA therapy. Two hundred nine patients with OSAH were recruited and analysed retrospectively. They had a polysomnographically documented apnoea-hypopnea index (AHI) of more than five respiratory events per hour. Lateral skull radiographs were used for cephalometric analysis. Only 67 of the 209 recruited patients underwent a second polysomnography (PSG) to evaluate the efficacy of OA therapy. In all recruited patients, the angle formed by the subspinal point (A) to the nasion (N) to the supramental point (B) (i.e. ANB angle) and the distance between the mandibular plane and hyoid bone (MP-H) were predictive factors of OSAH severity. In only 67 patients underwent PSG with an OA, the mean rate of decrease in the AHI was 47·8 ± 29·1%. OA therapy effectively treated OSAH in some patients with a very severe form of OSAH. However, patients who had a high position of the hyoid bone had a poor response to OA therapy. This study suggested that cephalometric analysis is useful for predicting OSAH severity and OA therapy efficacy.

An updatable holographic three-dimensional display

Holographic three-dimensional (3D) displays provide realistic images without the need for special eyewear, making them valuable tools for applications that require situational awareness, such as medical, industrial and military imaging. Currently commercially available holographic 3D displays use photopolymers that lack image-updating capability, resulting in restricted use and high cost. Photorefractive polymers are dynamic holographic recording materials that allow updating of images and have a wide range of applications, including optical correlation, imaging through scattering media and optical communication. To be suitable for 3D displays, photorefractive polymers need to have nearly 100% diffraction efficiency, fast writing time, hours of image persistence, rapid erasure, and large area-a combination of properties that has not been shown before. Here, we report an updatable holographic 3D display based on photorefractive polymers with such properties, capable of recording and displaying new images every few minutes. This is the largest photorefractive 3D display to date (4 x 4 inches in size); it can be recorded within a few minutes, viewed for several hours without the need for refreshing, and can be completely erased and updated with new images when desired.