A Complex Evaluation of the In-Vivo Biocompatibility and Degradation of an Extruded ZnMgSr Absorbable Alloy Implanted into Rabbit Bones for 360 Days.

The increasing incidence of trauma in medicine brings with it new demands on the materials used for the surgical treatment of bone fractures. Titanium, its alloys, and steel are used worldwide in the treatment of skeletal injuries. These metallic materials, although inert, are often removed after the injured bone has healed. The second-stage procedure-the removal of the plates and screws-can overwhelm patients and overload healthcare systems. The development of suitable absorbable metallic materials would help us to overcome these issues. In this experimental study, we analyzed an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. From this alloy we developed screws which were implanted into the rabbit tibia. After 120, 240, and 360 days, we tested the toxicity at the site of implantation and also within the vital organs: the liver, kidneys, and brain. The results were compared with a control group, implanted with a Ti-based screw and sacrificed after 360 days. The samples were analyzed using X-ray, micro-CT, and a scanning electron microscope. Chemical analysis revealed only small concentrations of zinc, strontium, and magnesium in the liver, kidneys, and brain. Histologically, the alloy was verified to possess very good biocompatibility after 360 days, without any signs of toxicity at the site of implantation. We did not observe raised levels of Sr, Zn, or Mg in any of the vital organs when compared with the Ti group at 360 days. The material was found to slowly degrade in vivo, forming solid corrosion products on its surface.

Zn-0.8Mg-0.2Sr (wt.%) Absorbable Screws-An In-Vivo Biocompatibility and Degradation Pilot Study on a Rabbit Model.

In this pilot study, we investigated the biocompatibility and degradation rate of an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. An alloy screw was implanted into one of the tibiae of New Zealand White rabbits. After 120 days, the animals were euthanized. Evaluation included clinical assessment, microCT, histological examination of implants, analyses of the adjacent bone, and assessment of zinc, magnesium, and strontium in vital organs (liver, kidneys, brain). The bone sections with the implanted screw were examined via scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). This method showed that the implant was covered by a thin layer of phosphate-based solid corrosion products with a thickness ranging between 4 and 5 µm. Only negligible changes of the implant volume and area were observed. The degradation was not connected with gas evolution. The screws were fibrointegrated, partially osseointegrated histologically. We observed no inflammatory reaction or bone resorption. Periosteal apposition and formation of new bone with a regular structure were frequently observed near the implant surface. The histological evaluation of the liver, kidneys, and brain showed no toxic changes. The levels of Zn, Mg, and Sr after 120 days in the liver, kidneys, and brain did not exceed the reference values for these elements. The alloy was safe, biocompatible, and well-tolerated.

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.

Evaluation of complications following stock replacement of the temporomandibular joint performed between the years 2006 and 2015: a retrospective study.

PURPOSE: Alloplastic total temporomandibular joint replacement (TMJR) is now considered to be a standard procedure for temporomandibular joint (TMJ) reconstruction. TMJR can improve mandibular mobility, restore the dental occlusion and improve facial aesthetics. The purpose was to assess the presence of intraoperative and post-operative complications, including the presence of post-operative chronic pain. METHODS: This retrospective study evaluated the use of 62 stock TMJR devices implanted in 45 patients who underwent surgery between the years 2006 and 2015 by the same surgeon at the Department of Oral and Maxillofacial Surgery, Stomatology Clinic, General Teaching Hospital (VFN) Charles University, Prague, Czech Republic. RESULTS: Intraoperative and post-operative complications recorded were facial nerve dysfunction (14-22%), open bite/malocclusion (2-3.2%), condylar component dislocation (1-1.6%), infection requiring revision surgery (1-1.6%) and (27-43%) reported chronic pain 24 months after surgery. CONCLUSIONS: As with any surgical procedure, TMJR can have complications. The results of this study demonstrate that the most common post-operative complication was continued pain. Chronic pain after TMJR was more common in patients with a preoperative diagnosis of degenerative joint disease. Also, the incidence of post-operative TMJR pain increased with the duration of symptoms prior to TMJR, leading to a question of the best timing for TMJR.

Evaluation of Complications Following a Trans-masseteric Antero-parotid Approach for Patients with Sub-condylar Fractures of Their Temporomandibular Joint. A Retrospective Study.

Sub-condylar fractures of the temporomandibular joint can be treated by an extraoral or intraoral approach. Trans-masseteric antero-parotid approach (TMAP) is an extraoral approach utilising a retromandibular incision. The authors evaluated patients' status and any complications of using TMAP from the years 2013-2017. There were 39 patients (44 fractures). When using TMAP, in 43 fractures the fragments were favourably positioned, in one case the position was compromised. Of the complications, postoperative palsy of the facial nerve was reported 6.8% - in all cases this was only temporary. Late occlusion had an equal number of complications (in 2 cases this was as a result of an infectious complication of the wound, and in 2 cases due to resorption of the proximal fragment). Muscular pain and dysfunction of the temporomandibular joint following trauma were observed consistently in 6.8% of patients. Sialocoele, a non-conforming scar, and infectious complications were observed in 4.5% of patients. TMAP allows rapid surgical performance, with a good view for perfect repositioning and fixation of fragments of sub-condylar fractures of the temporomandibular joint. The complications associated with this approach are, for the most part, temporary, the aesthetic handicap of a scar is considered by patients to be acceptable. Overall, it is possible to evaluate retromandibular TMAP as safe, and the authors recommended it for treatment of sub-condylar fractures of the mandible.

Lingual infarction in Wegener's Granulomatosis: a case report and review of the literature.

Wegener's granulomatosis (WG) is a multi-system disease, characterised by the triad of necrotising granulomata affecting the upper and lower respiratory tracts, disseminated vasculitis and glomerulonephritis. Oral lesions are associated with up to 50% of cases, although are rare as a presenting feature. The most common oral lesions associated with WG are ulceration and strawberry gingivitis. We review the literature regarding oral manifestations of WG and present a case of lingual infarction, an extremely rare oral lesion associated with WG, in a severe, rapidly progressive and ultimately fatal form of the disease.