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.

Evaluating the Effect of Conservative Therapy in Patients with Wilkes Stage III Temporomandibular Joint Derangement.

The authors evaluated effects of physiotherapy in patients experiencing Wilkes III temporomandibular joint (TMJ) derangement with clinically limited joint mobility, but no pain. The group consisted of 31 patients with unilateral temporomandibular joint involvement, 3 men and 28 women (average age was 30.93, ranging from age 12 to 61). None of the patients in the group had experienced any previous TMJ therapy. The patients underwent conservative therapy in the form of home exercise (mobilisation and isometric exercises) as the first step in treatment. The authors evaluated the improvement in jaw movement (maximal interincisal opening - MIO) and the patients' subjective assessments of their condition. Disc position before and after two months of exercise was also evaluated using ultrasound examination. The average MIO value in patients before starting the exercises was 33.5 mm, and after two months of exercises, 42.4 mm. Subjective assessment by patients: 26 patients (83%) described their condition as completely satisfactory, not requiring further therapy. Of these patients, ultrasound examination showed 10 patients with complete disc reduction, 9 patients with a change in disc displacement with reduction, and 7 patients with a continuing (unchanged) state of disc displacement. Results of our study show the effect of conservative therapy in patients with painless TMJ due to disc displacement (WIII). Effect of home exercises which were easy to perform, simple and acceptable to the patient were demonstrated.

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.

A prospective assessment of outcomes following the use of autologous blood for the management of recurrent temporomandibular joint dislocation.

PURPOSE: The objective of the study was to compare results of treatment for chronic recurrent temporomandibular joint dislocation (CRTMD) by autologous blood injection (ABI) using two different methods of administration (combination intra- and peri-articular, and peri-articular alone). MATERIALS AND METHODS: Forty patients diagnosed with CRTMD were randomly divided into two groups of 20 each (A and B). Group A were treated by intra- and peri-articular blood injection, group B were treated by peri-articular injection alone. The follow-up was done at 1, 3, 6, and 12 months. The study assessed presence of dislocations, pain (VAS, 0-10), interincisal mouth opening (IMO), and the presence of sound phenomena. The treatment was considered successful in patients without the persistence of CRTMD symptoms, as well as with a VAS of 0-1. RESULT: After 12 months, a beneficial therapeutic effect in group B was seen in 11 patients, while 16 patients from group A had a therapeutic effect. CONCLUSION: Intra- and peri-articular ABI is more effective than peri-articular blood application alone in the treatment of CRTMD, although the difference was not statistically significant.

In vivo study on biodegradable magnesium alloys: Bone healing around WE43 screws.

Introduction A standard osteosynthetic material for maxillofacial skeleton is titanium and its alloys. The convenience of degradable material is avoiding of second surgery in cases, where removal of the material is necessary. Magnesium biodegradable alloys have similar mechanic properties as cortical bone - reasonable corrosion and sufficient biologic properties. They might be used in facial skeleton fixation. Materials and methods The study included a total of 16 rabbits, and they were randomly divided into two groups. Each group received two screws (WE4 and titanium as a standard material) in artificially drilled defect into right tibia. Animals were euthanized at four-week intervals. Bone samples with implants underwent microfocus CT scans and were histologically examined. Results WE43 alloys showed fragmentation of the material on the 16th week - statistically significant volume loss was found between weeks 12 and 16. Bone healing around the WE43 screws was of similar quality as around titanium screws, and no adverse effect was noticed. Conclusion The study showed good quality of bone healing around WE43 implants. From this point of view, the WE43 alloy meets the requirements of osteosynthetic material for maxillofacial skeleton.