Fractures of the mandibular condyle: A comparison of patients, fractures and treatment characteristics between Groningen (The Netherlands) and Dresden (Germany).

PURPOSE: To explore differences in patient, fracture, accident and treatment characteristics between patients treated for a mandibular condyle fracture in the University Centres of Dresden and Groningen, as an explanation for differences treatment results. MATERIALS AND METHODS: Patients' fracture, accident and treatment characteristics were obtained from the medical records of Dresden and Groningen from January 1, 2008, to August 31, 2011, and were analysed using logistic regression analysis. RESULTS: In Dresden, compared to Groningen, patients were generally older (OR 1.03, 95% CI 1.02; 1.05, per year), were more often male (OR 2.54, 95% CI 1.48; 4.34) and more often had intracapsular (OR 2.95, 95% CI 1.67; 5.22) and low condylar (OR 1.86, 95% CI 1.14; 3.04) fractures. In Groningen 98% of patients received closed treatment and in Dresden 42%. CONCLUSION: Significant differences in patients and fractures and treatments were found between both Centres. These differences can partly be explained by the demographics of the cities and differences in imaging techniques (e.g., computed tomography, Orthopantomogram, Towne projection) applied to identify fractures. This study illustrates that differences in diagnosis, treatment and outcome are not only related to the health care system but also to differences in patient characteristics between centres.

Hemostatic action of polyurethane foam with 55% polyethylene glycol compared to collagen and gelatin.

BACKGROUND: For most topical hemostatic agents the mechanism of hemostatic action is not fully understood. OBJECTIVE: This work aimed to investigate the hemostatic mechanism of action and viscoelastic properties of polyurethane foam (PU) in comparison to the widely used collagen and gelatin. METHODS: The hemostatic mechanism of action of the materials was tested using human whole blood and platelet-poor plasma (PPP). The ability of the hemostatic agent to exert pressure on the wound was quantified in terms of its viscoelastic properties both under dry and wet conditions using a low load compression tester (LLCT). RESULTS: It has been shown that collagen and PU initiate hemostasis through both thrombocyte aggregation and contact activation of the coagulation cascade. Gelatin did not show improved thrombocyte aggregation or initiation of the coagulation cascade compared to the negative control group. PU is more firm under wet conditions and shows more springback than collagen and gelatin. CONCLUSIONS: We conclude that PU is promising as a topical hemostatic agent because it initiates both the coagulation cascade and thrombocyte aggregation. Furthermore, it has favorable viscoelastic properties compared to collagen and gelatin which leads to increased pressure on a wound.

In vivo degradation of polyurethane foam with 55 wt % polyethylene glycol.

Most topical hemostatic agents are based on animal-derived products like collagen and gelatin. They carry the potential risk of pathogen transmission while adjustments in the production process of these materials are limited. A synthetic hemostatic agent based on polyurethane (PU) and polyethylene glycol (PEG) was developed to overcome these disadvantages. The goal of this study was to compare the degradation process of this biomaterial to collagen and gelatin hemostatic agents. Samples of the test materials were implanted subcutaneously in both rats and rabbits. The animals were sacrificed at certain time intervals up to three years and the explanted samples were microscopically assessed. The histological examination showed a comparable pattern of degradation for the different test materials. Remnants of gelatin and collagen were seen up to 26 and 39 weeks, respectively. For PU, it took up to three years before micro-particles of the material were no longer detected. All biomaterials showed a good biocompatibility and no severe foreign body reactions occurred. The good biocompatibility and predictable pattern of resorption indicate that PU can be used as a topical hemostatic agent. However, a degradation time comparable to collagen and gelatin would be favorable.

Risk of bleeding after dentoalveolar surgery in patients taking anticoagulants.

To avoid increasing the risk of thromboembolic events, it is recommended that treatment with anticoagulants should be continued during dentoalveolar operations. We have evaluated the incidence of bleeding after dentoalveolar operations in a prospective study of 206 patients, 103 who were, and 103 who were not, taking anticoagulants. Seventy-one were taking thrombocyte aggregation inhibitors and 32 vitamin K antagonists. Patients were treated according to guidelines developed at the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands. The operations studied included surgical extraction (when the surgeon had to incise the gingiva before extraction), non-surgical extraction, apicectomy, and placement of implants. Patients were given standard postoperative care and those taking vitamin K antagonists used tranexamic acid mouthwash postoperatively. No patient developed a severe bleed that required intervention. Seven patients (7%) taking anticoagulants developed mild postoperative bleeds. Patients taking vitamin K antagonists reported 3 episodes (9%) compared with 4 (6%) in the group taking thrombocyte aggregation inhibitors. Among patients not taking anticoagulants, two (2%) developed mild bleeding. The differences between the groups were not significant. All bleeding was controlled by the patients themselves with compression with gauze. We conclude that dentoalveolar surgery is safe in patients being treated with anticoagulants provided that the conditions described in the ACTA guidelines are met.

In vivo hemostatic efficacy of polyurethane foam compared to collagen and gelatin.

OBJECTIVES: Topical hemostatic agents are used in all surgical disciplines. Most of these hemostats are based on animal-derived products like collagen and gelatin. They carry the potential risk of pathogen transmission. A newly developed biodegradable, fully synthetic hemostatic agent based on polyurethane foam (PU) with 55 % polyethylene glycol (PEG) would prevent these potential risks. MATERIALS AND METHODS: The hemostatic efficacy of this new agent was compared to gelatin and collagen in humans who underwent extraction of an upper and lower molar (split-mouth model). After extraction of a molar in the maxilla and mandible, a PU foam and collagen or gelatin were inserted in the extraction socket for 2 min. Hereafter, the agents were removed and stored in ethylenediaminetetraacetic acid to stop coagulation. Then, the concentration of coagulation parameters thrombin-antithrombin III (TAT) complexes, fibrinogen, and thromboxane B2 (TxB2) in blood extracts from the agents was measured. The concentrations were also determined in baseline blood samples which were collected from the extraction socket. RESULTS: The concentrations of TAT and TxB2 were significantly increased, and fibrinogen concentration was significantly reduced compared to baseline wound blood concentrations indicating enhanced hemostasis. No significant differences were seen in the concentrations of these coagulation parameters in the three different hemostatic agents. CONCLUSIONS: These results show that PU combined with 55 % PEG is a promising alternative for the animal-derived hemostatic agents. CLINICAL RELEVANCE: The synthetic hemostatic agent could replace the animal-derived products like collagen and gelatin and therewith prevent the potential risk of pathogen transmission.

Composite materials based on poly(trimethylene carbonate) and ß-tricalcium phosphate for orbital floor and wall reconstruction.

Poly(trimethylene carbonate) and ß-tricalcium phosphate (PTMC/ß-TCP) composite materials were prepared by coprecipitation and compression molding. The effect of different amounts of the ceramic component (15 and 30 vol %) on the properties was investigated. The effect of lamination with minimal amounts of poly(D,L-lactide) (PDLLA) was assessed as well. It was hypothesized that these composites would be suitable for orbital floor reconstruction, as the polymer component resorbs enzymatically without the formation of acidic compounds, while the ceramic component could induce bone formation. To asses their suitability as load bearing devices, the flexural properties of the prepared (laminated) composites were determined in three point bending experiments and compared with those of currently used reconstruction devices. The flexural modulus of PTMC composites increased from 6-17 MPa when introducing 30 vol % ß-TCP. A laminate of this composite with PDLLA (with respective layer thicknesses of 0.8 and 0.2 mm) had a flexural modulus of 64 MPa. When evaluated in a mechanical engineering model of the orbital floor the (laminated) composites materials showed similar behavior compared to the currently used materials. The results suggest that from a mechanical point of view these (laminated) composite sheets should be well suited for use in orbital floor reconstruction.

In vitro analysis of polyurethane foam as a topical hemostatic agent.

Topical hemostatic agents can be used to treat problematic bleedings in patients who undergo surgery. Widely used are the collagen- and gelatin-based hemostats. This study aimed to develop a fully synthetic, biodegradable hemostatic agent to avoid exposure to animal antigens. In this in vitro study the suitability of different newly developed polyurethane-based foams as a hemostatic agent has been evaluated and compared to commonly used agents. An experimental in vitro test model was used in which human blood flowed through the test material. Different modified polyurethane foams were compared to collagen and gelatin. The best coagulation was achieved with collagen. The results of the polyurethane foam improved significantly by increasing the amount of polyethylene glycol. Therefore, the increase of the PEG concentration seems a promising approach. Additional in vivo studies will have to be implemented to assess the application of polyurethane foam as a topical hemostatic agent.

Feasibility of conical biodegradable polyurethane foam for closure of oroantral communications.

PURPOSE: To assess the feasibility of a conically shaped biodegradable polyurethane (PU) foam for closure of oroantral communications (OACs). PATIENTS AND METHODS: In 10 consecutive patients, fresh OACs (present for <24 hours) were closed with PU foam. Standardized evaluations were performed at 2 and 8 weeks after closure of the OAC. Success was considered permanent closure of the OAC. RESULTS: No complications were observed in 7 of the 10 patients. Of the other 3 patients, 1 developed a maxillary sinusitis that was successfully managed with antibiotics and the OAC recurred in 2 patients. CONCLUSIONS: Permanent closure of the OAC using PU foam was accomplished in 8 of 10 patients. The results obtained in the present study were more favorable than in a previous feasibility study. Therefore, the alterations in the treatment protocol were maintained for additional research of this new and straightforward treatment strategy. In general, closure of OACs with biodegradable PU foam is feasible and has the potential to make surgical treatment unnecessary for a large number of patients with OACs.

Fixation of osteochondral fragments in the human knee using Meniscus Arrows.

The aim of this study is to compare the hold in bone of Meniscus Arrows and Smart Nails, followed by the report of the results of the clinical application of Meniscus Arrows as fixation devices. First, pull-out tests were performed to analyse the holdfast of both nails in bone. Statistical analysis showed no significant difference; therefore, the thinner Meniscus Arrow was chosen as fixation device in the patient series of two patients with a symptomatic Osteochondritis dissecans fragment and three patients with an osteochondral fracture of a femur condyle. The cartilage margins were glued with Tissuecoll. All fragments consolidated. Second look arthroscopy in three patients showed fixed fragments with stable, congruent cartilage edges. At an average follow-up period of 5 years no pain, effusion, locking, restricted range of motion or signs of osteoarthritis were reported. Based on the results of the pull-out tests and available clinical studies, Meniscus Arrows and Smart Nails are both likely to perform adequately as fixation devices in the treatment of Osteochondritis dissecans and osteochondral fractures in the knee. They both provide the advantage of one stage surgery. However, based on their smaller diameter, the Meniscus Arrows should be preferred for this indication.

Closure of oroantral communications using biodegradable polyurethane foam: a feasibility study.

PURPOSE: The aim of this study was to assess the feasibility of biodegradable polyurethane (PU) foam for closure of oroantral communications (OACs). PATIENTS AND METHODS: Ten consecutive patients with OACs (existing <24 hours) were treated with PU foam. Standardized evaluations were performed at 2 weeks and 8 weeks after closure of the OAC. RESULTS: In 5 patients, the OACs were closed successfully without complications. Three patients developed sinusitis, which was conservatively managed with antibiotics in 2 cases. In 1 case the sinus was reopened for irrigation, after which a buccal flap procedure was performed. In 2 patients the OAC recurred and was surgically closed with a buccal flap after thorough irrigation. CONCLUSION: In this feasibility study, closure was achieved in 7 of the 10 patients without further surgical intervention. Complications of the procedure using PU foam may be related to the fit of the foam in the socket and the size of the perforation. In general, closure of OACs with biodegradable polyurethane foam is feasible and has the potential to spare a large number of patients with OACs a surgical procedure. Furthermore, in case the treatment with PU foam fails to close the OAC, the attending physician can always fall back on the standard surgical procedure.

Closure of oroantral communications using biodegradable polyurethane foam: a long term study in rabbits.

An oroantral communication (OAC) is an open connection between the oral cavity and maxillary sinus. Closure of OACs is commonly performed with a surgical procedure using a mucoperiosteal flap. An alternative technique using synthetic biodegradable polyurethane (PU) foam for closure of OACs is presented. This PU foam is composed of hard urethane segments, and soft segments made of D/L lactide (50/50), epsilon-caprolactone, and 5% polyethyleneglycol (PEG). To evaluate the use of PU foam for this application, OACs were created in the edentulous part of the maxilla in 21 rabbits, after which PU foams were fitted in the defects. Results showed complete healing of the oral mucosa after 4-10 weeks, healing of the antral mucosal lining after 6 months and complete bony regeneration after 1 year. No reopening of the defects occurred and no maxillary sinusitis was observed. Degradation of the PU foam had not yet reached completion 1 year after implantation. In conclusion, PU foam with 5% PEG provides adequate closure of an OAC in the rabbit model to support healing of the oral and maxillary sinus mucosa. Longer time intervals are needed to assess the complete degradation of the PU foam.

Is the pull-out force of the Meniscus Arrow in bone affected by the inward curling of the barbs during biodegradation? An in vitro study.

BACKGROUND: Inward curling of the barbs of Meniscus Arrows during degradation was observed in a previous study, in which swelling, distention, and water uptake by Meniscus Arrows was evaluated. This change of configuration could have consequences with respect to anchorage capacity in bone. MATERIAL/METHODS: Eight non-degraded Meniscus Arrows in the original configuration were pulled out of thawed, fresh-frozen human femoral condyle, and pull-out force was measured and compared with that of 6 Meniscus Arrows after 31 days of degradation under controlled conditions. RESULTS: No significant difference was found between the 2 groups with respect to the required pull-out force (t test), the distribution of the data, or the interaction between degradation and location, as evaluated by Mann-Whitney test, and no significant difference was found between the 2 groups with respect to the degradation state or position in the condyles, as evaluated by 2-way analysis of variance. CONCLUSIONS: Our results indicate that the decrease in barb-barb diameter during the first month of degradation of the Meniscus Arrows has no significant effect on the tensile pull-out force required for removal from human femur condyle. Further research should be undertaken to examine whether the same is true for other biodegradable devices with barbs.

Mechanical strength and stiffness of the biodegradable SonicWeld Rx osteofixation system.

PURPOSE: To determine the mechanical strength and stiffness of the new 2.1 mm biodegradable ultrasound-activated SonicWeld Rx (Gebrüder Martin GmbH & Co, Tuttlingen, Germany) osteofixation system in comparison with the conventional 2.1 mm biodegradable Resorb X (Gebrüder Martin GmbH & Co) osteofixation system. MATERIALS AND METHODS: Plates and screws were fixed to 2 polymethylmethacrylate blocks to simulate bone segments and were subjected to tensile, side bending, and torsion tests. During testing, force and displacement were recorded and graphically presented in force-displacement diagrams. For the tensile tests, the strength of the osteofixation system was measured. The stiffness was calculated for the tensile, side bending, and torsion tests. RESULTS: The tensile strength and stiffness as well as the side bending stiffness of the SonicWeld Rx system presented up to 11.5 times higher mean values than the conventional Resorb X system. The torsion stiffness of both systems presents similar mean values and standard deviations. CONCLUSIONS: The SonicWeld Rx system is an improvement in the search for a mechanically strong and stiff as well as a biodegradable osteofixation system. Future research should be done to find out whether the promising in vitro results can be transferred to the in situ clinical situation.

Should in the treatment of osteochondritis dissecans biodegradable or metallic fixation devices be used? A comparative study in goat knees.

Most of the metallic devices have to be removed, treating osteochondritis dissecans lesions. This animal study describes the biological and mechanical behavior of screws and pins, made of commercially available PGA/PLA and PLA96 and metallic screws and pins, used for fragment fixation. A sham operation served as control. A tissue reaction with cavity formation was observed around every PGA/PLA screw, beginning at 12 weeks following insertion, in contrast to once around a PLA96 screw (p < 0.001), once around one of the 16 PGA/PLA pins and never around those, made of PLA96 (no significance). Disintegration of the PGA/PLA devices started 6 weeks following implantation against 34 weeks for the PLA96 implants. The gap between the fragment and the recipient cartilage disappeared only in the sham group. Many fragments of PGA/PLA material were found in the synovia, in contrast with just a few fragments in the PLA96 group, causing a mild cellular reaction. No polymer particles were found in the draining lymph nodes at any interval. In conclusion, the tested biodegradable screws should not be used for fragment fixation in the treatment of osteochondritis dissecans. Either an undesirable tissue reaction can be expected (PGAPLA), or, because of the slow degradation (PLLA), a screw might damage the opposite cartilage during weight bearing. Two biodegradable pins provide a safe rotational stability and should be combined with one metallic screw, providing compression. This screw has to be removed before loading the limb to prevent cartilage wear of the opposite tibia plateau.

Will the hold of solid biodegradable implants be influenced by swelling during the degradation process? An in-vitro study with Meniscus Arrows.

Water uptake after implantation of biodegradable devices induces swelling, as mentioned in literature. The hold in bone of solid devices will increase if the swelling is substantial enough. The results of weighing six Meniscus Arrows (MAs) before and after immersion in a sterile phosphate buffered saline solution during different time intervals were compared with the outcome of measurements under a field emission scanning electron microscope of six other MAs, stored under comparable conditions. The data were statistically evaluated with the Wilcoxon's signed rank test. The weight increase of 2.1 mg or 9.16% was statistically significant in the first 2 h following immersion, remaining stable afterwards with an average weight gain of 1.7 mg or 7.18%. The core diameter of the MAs increased to 0.01 mm or 1.01% with time. Although this is statistically significant, it is not expected to have any consequences for the hold. However, a remarkable and statistically significant decrease in the outer inter-barb diameter of 0.15 mm or 8.6% was noted with time. Mechanical testing should reveal the clinical relevance of the results of this study.

Nonsurgical closure of oroantral communications with a biodegradable polyurethane foam: A pilot study in rabbits.

PURPOSE: Surgical closure of oroantral communications (OACs) has several disadvantages. An animal study was performed to test whether OACs can be closed nonsurgically with a biodegradable polyurethane (PU) foam. MATERIALS AND METHODS: In 6 rabbits, an OAC was created on both sides of the maxilla. Three rabbits were used to evaluate the animal model by applying a surgical treatment on 1 side and by leaving the other defects untreated. In the 3 other rabbits, OACs were closed with PU foam. Wound healing was evaluated clinically and histologically. RESULTS: The surgically treated defects healed without complications. The untreated defects showed complicated and delayed healing. Healing of the foam-treated OACs was dependent on the type of foam that was used. CONCLUSIONS: The rabbit is a suitable animal model for OAC investigations. It is possible to close an OAC with a biodegradable PU foam. Further research is needed to show the most suitable composition of the PU for this purpose.

Resorbable screws for fixation of autologous bone grafts.

The aim of this study was to evaluate the suitability of resorbable screws made of poly (D.L-lactide) acid (PDLLA) for fixation of autologous bone grafts related to graft regeneration and osseointegration of dental implants. In eight edentulous patients suffering from insufficient retention of their upper denture related to a severely resorbed maxilla, the floor of both maxillary sinus and width of the alveolar crest were augmented with an autologous bone graft from the iliac crest. Randomly, the bone graft used to augment the alveolar crest was fixed with two titanium screws on one side and two resorbable screws on the other side (split-mouth design). Three months after the reconstruction, a bone biopsy was taken with a trephine including one resorbable screw (N = 8). Subsequently, six implants were placed in the left and right posterior maxilla. Six months later, at the abutment connection, a bone biopsy was taken including the other resorbable screw (N = 8). The biopsies were processed for light microscopic examination. In addition, clinical parameters were scored. Wound healing was uneventful. Clinically no difference in wound healing was observed between sides treated with either a resorbable or titanium screw. No implants were lost. Six months after implantation, implant retained overdentures could be fabricated in all patients. All patients functioned well with their overdentures (follow-up 22.2 +/- 4.3 months). Three as well as 9 months after insertion (remnants of), the resorbable screws were still visible after reflecting the mucoperiosteum. Histological examination confirmed that a considerable quantity of remnants of the resorbable screws was still present, although areas with some fragmentation of the PDLLA were also observed. The screws were separated by a fibrous tissue layer containing many giant cells from the bone. Particles of PDLLA were observed within these giant cells. This study revealed that resorbable screws made of PDLLA can be used for fixation of bone grafts. The bulk of the PDLLA material is still present after 9 months.