External fixation greatly improves outcomes in the surgical treatment of osteoradionecrosis of the jaws without affecting quality of life: a five-year retrospective study.

Osteoradionecrosis of the jaw can be treated using both conservative treatment and surgery. External fixation may be used to bridge large resection defects after sequestrectomy for stabilisation and before secondary mandibular reconstruction. We designed a retrospective analysis of 70 patients with osteoradionecrosis treated between the years 2014 and 2018, and found that the use of external fixation greatly improves their outcomes. Patients were grouped according to Notani's classification: those who had Notani I disease were treated surgically but without external fixation; and those with Notani II and Notani III disease were eligible for external fixation. In those with Notani II disease, there was a significant reduction in the number of pathological fractures that occurred with external fixation. In those with Notani III disease, the success rate of primary sequestrectomy was only 1:14; however, those treated with external fixation all successfully healed after their first operation. It was hypothesised that although external fixation would improve outcome, it would come at a detriment to their quality of life (QoL). However, in a subset of these patients, we showed that in addition to increasing successful healing, patients' QoL with the external fixator was no worse than when they had an active osteonecrotic lesion. The treatment of osteoradionecrosis is cumbersome and advanced stages are associated with more complications. The use of an external fixator significantly reduces the probability of pathological fractures and increases the rate of successful healing in patients after mandibular resection. It does this without greatly interfering with patients' lives, while improving their condition sufficiently to allow for subsequent mandibular reconstruction.

Movement of the patient and the cone beam computed tomography scanner: objectives and possible solutions.

OBJECTIVE: This study aimed (1) to determine whether scanner arm rotation causes significant movement of the head restraint and (2) to measure patient movement and its variation during the scan. STUDY DESIGN: The iCAT scanner and a high-speed camera were used. The 40 patients were divided into 2 groups: the open-eyed group and the blindfolded group. RESULTS: The mean level of head restraint movement was 0.130 mm, with a significantly higher level at the beginning, probably owing to the accelerating arm. Mean movement of patients was 1.135 mm and 1.119 mm in the open-eyed and blindfolded groups, respectively. Patient movement was also significantly higher at the beginning of the scan, when noise and vibrations are likely to surprise the patient. CONCLUSIONS: Patient instruction and a dry-run scan should be done by clinicians. Manufacturers should consider separating the seat and head restraint from the rest of the scanner to avoid vibration transfer.

The influence of orthognathic surgery on ventilation during sleep.

Orthognathic surgery has varying effects on respiratory parameters. The authors undertook a prospective study of patients requiring mandibular advancement, mandibular setback and maxillary Le Fort I advancement, and surgically assisted rapid maxillary expansion (SARME). Breathing parameters were monitored in a sleep laboratory the night before the operation and in a mean of 9.5 months after the operation. In patients treated with mandibular advancement, the respiratory disturbance index (RDI), oxygen desaturation index (ODI), and number of obstructive apnoeas (OAs) improved significantly. In patients treated with mandibular setback and maxillary Le Fort I advancement, the RDI, ODI, index of flow limitations (IFL), number of obstructive hypopnoeas (OHs), OA, and oxygen saturation deteriorated. In contrast, patients treated with SARME improved only mildly. These results indicate that bimaxillary surgery for Class III malocclusion increased upper airway resistance, probably because of a more dorsal positioning of the base of the tongue, representing an iatrogenic obstructive sleep apnoea (OSA). A young person would probably be able to balance such a decline in respiratory function using different adaptative mechanisms. Mandibular advancement significantly improved respiratory parameters during sleep. The possible effect of orthognathic surgery on the upper airways should be incorporated into the treatment plan.

Myosin heavy chain proteins are responsible for the development of obstructive sleep apnea syndrome.

We introduce a hypothesis that obstructive sleep apnea syndrome (OSAS) is primarily caused by an inherited reduced adaptability of upper airway striated muscles such that they cannot maintain patency when there is reduced consciousness (sleep). This reduced ability is caused by a deficiency of the genes for specific myosin heavy chain (MHC) proteins, which are the primary source of muscle adaptability in adults and were initially described in the chewing muscles. The development of OSAS must be linked to problems with striated muscle because affected patients are capable of normal breathing when awake but their respiratory parameters deteriorate during sleep; OSAS must, therefore, be caused by a factor that is voluntarily active during waking but inactive during sleep, and this can only be striated muscle. Congenital or acquired anatomical abnormalities are involved only partially, because OSAS patients with anatomical abnormalities do not begin to snore or to have apneas or hypopneas when lying in bed awake, but begin to do so only when sleeping.