The behaviour of titanium as a biomaterial: microscopy study of plates and surrounding tissues in facial osteosynthesis

Titanium or Biodegradable Osteosynthesis in Maxillofacial Surgery? In Vitro and In Vivo Performances

Osteosynthesis systems are used to fixate bone segments in maxillofacial surgery. Titanium osteosynthesis systems are currently the gold standard. However, the disadvantages result in symptomatic removal in up to 40% of cases. Biodegradable osteosynthesis systems, composed of degradable polymers, could reduce the need for removal of osteosynthesis systems while avoiding the aforementioned disadvantages of titanium osteosyntheses. However, disadvantages of biodegradable systems include decreased mechanical properties and possible foreign body reactions. In this review, the literature that focused on the in vitro and in vivo performances of biodegradable and titanium osteosyntheses is discussed. The focus was on factors underlying the favorable clinical outcome of osteosyntheses, including the degradation characteristics of biodegradable osteosyntheses and the host response they elicit. Furthermore, recommendations for clinical usage and future research are given. Based on the available (clinical) evidence, biodegradable copolymeric osteosyntheses are a viable alternative to titanium osteosyntheses when applied to treat maxillofacial trauma, with similar efficacy and significantly lower symptomatic osteosynthesis removal. For orthognathic surgery, biodegradable copolymeric osteosyntheses are a valid alternative to titanium osteosyntheses, but a longer operation time is needed. An osteosynthesis system composed of an amorphous copolymer, preferably using ultrasound welding with well-contoured shapes and sufficient mechanical properties, has the greatest potential as a biocompatible biodegradable copolymeric osteosynthesis system. Future research should focus on surface modifications (e.g., nanogel coatings) and novel biodegradable materials (e.g., magnesium alloys and silk) to address the disadvantages of current osteosynthesis systems.

In vivo performance of a rare earth free Mg–Zn–Ca alloy manufactured using twin roll casting for potential applications in the cranial and maxillofacial fixation devices

A magnesium alloy containing essential, non-toxic, biodegradable elements such as Ca and Zn has been fabricated using a novel twin-roll casting process (TRC). Microstructure, mechanical properties, in vivo corrosion and biocompatibility have been assessed and compared to the properties of the rare earth (RE) element containing WE43 alloy. TRC Mg-0.5 wt% Zn- 0.5 wt% Ca exhibited fine grains with an average grain size ranging from 70 to 150 μm. Mechanical properties of a TRC Mg-0.5Zn-0.5Ca alloy showed an ultimate tensile strength of 220 MPa and ductility of 9.3%. The TRC Mg-0.5Zn-0.5Ca alloy showed a degradation rate of 0.51 ± 0.07 mm/y similar to that of the WE43 alloy (0.47 ± 0.09 mm/y) in the rat model after 1 week of implantation. By week 4 the biodegradation rates of both alloys studied were lowered and stabilized with fewer gas pockets around the implant. The histological analysis shows that both WE43 and TRC Mg-0.5Zn-0.5Ca alloy triggered comparable tissue healing responses at respective times of implantation. The presence of more organized scarring tissue around the TRC Mg-0.5Zn-0.5Ca alloys suggests that the biodegradation of the RE-free alloy may be more conducive to the tissue proliferation and remodelling process.

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Mg-0.5Zn-0.5Ca alloy plates were fabricated by a twin-roll casting (TRC) process.

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TRC alloy showed an ultimate strength and elongation of 221 ± 2 MPa and 9 ± 2%.

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Gas development during in vivo degradation was analysed using μ-CT techniques.

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Histological analysis revealed a good biocompatibility and promoted healing.

Biocompatible Materials in Otorhinolaryngology and Their Antibacterial Properties

For decades, biomaterials have been commonly used in medicine for the replacement of human body tissue, precise drug-delivery systems, or as parts of medical devices that are essential for some treatment methods. Due to rapid progress in the field of new materials, updates on the state of knowledge about biomaterials are frequently needed. This article describes the clinical application of different types of biomaterials in the field of otorhinolaryngology, i.e., head and neck surgery, focusing on their antimicrobial properties. The variety of their applications includes cochlear implants, middle ear prostheses, voice prostheses, materials for osteosynthesis, and nasal packing after nasal/paranasal sinuses surgery. Ceramics, such as as hydroxyapatite, zirconia, or metals and metal alloys, still have applications in the head and neck region. Tissue engineering scaffolds and drug-eluting materials, such as polymers and polymer-based composites, are becoming more common. The restoration of life tissue and the ability to prevent microbial colonization should be taken into consideration when designing the materials to be used for implant production. The authors of this paper have reviewed publications available in PubMed from the last five years about the recent progress in this topic but also establish the state of knowledge of the most common application of biomaterials over the last few decades.

The Implications of Titanium Alloys Applied in Maxillofacial Osteosynthesis

Titanium alloys are known for their biological, mechanical and chemical properties, which have successfully expanded their use in the maxillofacial field. The internal fixation using titanium miniplates and screws offer a new perspective for the treatment of trauma and in orthognathic surgery and maxillofacial oncology. Although, titanium is highly recommended for its excellent biocompatibility, recent research has focused on identifying the potential local and general implications of the interactions between the human tissue and the metallic particles. This present review aims to outline the existing tissue changes, cellular alterations and future perspectives regarding the use of titanium-based alloys as osteosynthesis materials, taking into consideration the existing present debate whether the routinely removal of these materials should be an indication.

Atomic Scale Origin of Metal Ion Release from Hip Implant Taper Junctions

Millions worldwide suffer from arthritis of the hips, and total hip replacement is a clinically successful treatment for end-stage arthritis patients. Typical hip implants incorporate a cobalt alloy (Co-Cr-Mo) femoral head fixed on a titanium alloy (Ti-6Al-4V) femoral stem via a Morse taper junction. However, fretting and corrosion at this junction can cause release of wear particles and metal ions from the metallic implant, leading to local and systemic toxicity in patients. This study is a multiscale structural-chemical investigation, ranging from the micrometer down to the atomic scale, of the underlying mechanisms leading to metal ion release from such taper junctions. Correlative transmission electron microscopy and atom probe tomography reveals microstructural and compositional alterations in the subsurface of the titanium alloy subjected to in vitro gross-slip fretting against the cobalt alloy. Even though the cobalt alloy is comparatively more wear-resistant, changes in the titanium alloy promote tribocorrosion and subsequent degradation of the cobalt alloy. These observations regarding the concurrent occurrence of electrochemical and tribological phenomena are vital to further improve the design and performance of taper junctions in similar environments.

No Need to Routinely Remove Titanium Implants for Maxillofacial Fractures

PURPOSE

Titanium implants are typically used to fix maxillofacial fractures and their routine removal is a controversial topic in maxillofacial surgery. This study aimed to estimate the removal rate and risk factors associated with removal.

MATERIALS AND METHODS

The authors designed and implemented a retrospective study. Adult patients who underwent open reduction and internal fixation with titanium implants for maxillofacial fractures were included and those who returned for implant removal were identified from January 2007 to December 2016. The predictor variables were gender, age, preoperative infection, injury time, trauma cause, and fracture site. The primary outcome variable was removal of titanium implants. Descriptive and bivariate statistics were computed. Kaplan-Meier survival methods were used to estimate rate of removal. Univariate and multivariate Cox proportional hazards models were used to identify risk factors associated with removal.

RESULTS

Of 2,325 patients (1,890 men and 435 women; average age, ∼35.49 yr) registered in this study, 163 (7.01%) had their titanium implants removed and 1-, 2-, and 10-year removal rates were 3, 7, and 8%, respectively. The risk factors most closely associated with removal were preoperative infection, injury by a blow from an object, obsolete fracture, and female gender.

CONCLUSIONS

Routinely removing titanium implants in patients with maxillofacial fracture is not necessary. When the risk factors listed earlier are present in these patients, follow-up should be scheduled more frequently.

Novel Nanoparticulate and Ionic Titanium Antigens for Hypersensitivity Testing

Titanium is used in a wide variety of materials ranging from medical devices to materials used in everyday life. Adverse biological reactions that could occur in patients, consumers, and workers should be monitored and prevented. There is a lack of available agents to test and predict titanium-related hypersensitivity. The aim of this study was to develop two bioavailable titanium substances in ionic and nanoparticulate form to serve as antigens for hypersensitivity testing in vitro. Peripheral blood mononuclear cells from 20 test subjects were stimulated with the antigens and secretion of monocytic and lymphatic cytokines and chemokines were measured by a multiplex bead assay. Lymphocyte stimulation indices were also determined in a subset of test subjects by measuring CD69 and HLA-DR expression by flow cytometry. Cytokine profiling revealed that both antigens increased production of typical monocyte and macrophage secreted cytokines after 24 h, with significant increases in IL-1β, IL-7, IL-10, IL-12, IL-2R, IL-6, GM-CSF, TNF-α, IL-1RA, MIP-1α, MIP-1β, IFN-α, and IL-15. Lymphatic cytokines and chemokines were not significantly induced by activation. After seven days of stimulation, ionic-Ti (2.5 μg/mL) caused proliferation (stimulation index > 2) of CD4+ cells and CD8+ cells in all persons tested (N = 6), while titanium dioxide nanoparticles (50 μg/mL) only caused significant proliferation of CD4+ cells. Our preliminary results show that the experimental titanium antigens, especially the ionic form, induce a general inflammatory response in vitro. A relevant cohort of test subjects is required to further elucidate their potential for predictive hypersensitivity testing.

Recent advances in the reconstruction of cranio-maxillofacial defects using computer-aided design/computer-aided manufacturing

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM) technology, it has been possible to reconstruct the cranio-maxillofacial defect with more accurate preoperative planning, precise patient-specific implants (PSIs), and shorter operation times. The manufacturing processes include subtractive manufacturing and additive manufacturing and should be selected in consideration of the material type, available technology, post-processing, accuracy, lead time, properties, and surface quality. Materials such as titanium, polyethylene, polyetheretherketone (PEEK), hydroxyapatite (HA), poly-DL-lactic acid (PDLLA), polylactide-co-glycolide acid (PLGA), and calcium phosphate are used. Design methods for the reconstruction of cranio-maxillofacial defects include the use of a pre-operative model printed with pre-operative data, printing a cutting guide or template after virtual surgery, a model after virtual surgery printed with reconstructed data using a mirror image, and manufacturing PSIs by directly obtaining PSI data after reconstruction using a mirror image. By selecting the appropriate design method, manufacturing process, and implant material according to the case, it is possible to obtain a more accurate surgical procedure, reduced operation time, the prevention of various complications that can occur using the traditional method, and predictive results compared to the traditional method.

Formation of hydroxyapatite on titanium implants in vivo precedes bone-formation during healing

The bone material interface has been an area of intense study over many decades, where studies of the healing process ranging from simple mineral deposition in vitro to actual healing in vivo have given important clues to the importance of calcium minerals in the bone/implant interface. Here, the authors use a combination of in vitro cell culture methods and in vivo implantation to study how the role of the spontaneously formed hydroxyapatite layer on Ti-implants for the in vivo-healing into the bone tissue of rat tibia. Initial experiments were made in reduced systems by incubation of TiO₂ in cell culture medium and analysis by time of flight secondary ion mass spectrometry (ToF-SIMS) and energy-dispersive x-ray spectroscopy followed by subsequent exposure of human embryological stem cells analyzed by von Kossa staining and environmental scanning electron microsopy. In vivo studies of the bone-material interface was analyzed by ToF-SIMS depth profiling using both C₆₀⁺ ions as well as a gas cluster ion source beam, Ar₁₅₀₀⁺ as sputter source. The low ion yield of the Ar₁₅₀₀⁺ for inorganics allowed the inorganic/organic interface of the implant to be studied avoiding the erosion of the inorganic materials caused by the conventional C₆₀⁺ beam.

Evolution of design considerations in complex craniofacial reconstruction using patient-specific implants

Previously published evidence has established major clinical benefits from using computer-aided design, computer-aided manufacturing, and additive manufacturing to produce patient-specific devices. These include cutting guides, drilling guides, positioning guides, and implants. However, custom devices produced using these methods are still not in routine use, particularly by the UK National Health Service. Oft-cited reasons for this slow uptake include the following: a higher up-front cost than conventionally fabricated devices, material-choice uncertainty, and a lack of long-term follow-up due to their relatively recent introduction. This article identifies a further gap in current knowledge – that of design rules, or key specification considerations for complex computer-aided design/computer-aided manufacturing/additive manufacturing devices. This research begins to address the gap by combining a detailed review of the literature with first-hand experience of interdisciplinary collaboration on five craniofacial patient case studies. In each patient case, bony lesions in the orbito-temporal region were segmented, excised, and reconstructed in the virtual environment. Three cases translated these digital plans into theatre via polymer surgical guides. Four cases utilised additive manufacturing to fabricate titanium implants. One implant was machined from polyether ether ketone. From the literature, articles with relevant abstracts were analysed to extract design considerations. In all, 19 frequently recurring design considerations were extracted from previous publications. Nine new design considerations were extracted from the case studies – on the basis of subjective clinical evaluation. These were synthesised to produce a design considerations framework to assist clinicians with prescribing and design engineers with modelling. Promising avenues for further research are proposed.

Titanium wound chambers for wound healing research

Standardized and reproducible animal models are crucial in medical research. Rodents are commonly used in wound healing studies since, they are easily available, affordable and simple to handle and house. However, the most significant limitation of rodent models is that the wounds heal by contraction while in humans the primary mechanisms of healing are reepithelialization and granulation tissue formation. The robust contraction results in faster wound closure that complicates the reproducibility of rodent studies in clinical trials. We have developed a titanium wound chamber for rodent wound healing research. The chamber is engineered from two pieces of titanium and is placed transcutaneously on the dorsum of a rodent. The chamber inhibits wound contraction and provides a means for controlled monitoring and sampling of the wound environment in vivo with minimal foreign body reaction. This technical report introduces two modalities utilizing the titanium chambers in rats: (1) Wound in a skin island model and, (2) Wound without skin model. Here, we demonstrate in rats how the "wound in a skin island model" slows down wound contraction and how the "wound without skin" model completely prevents the closure. The titanium wound chamber provides a reproducible standardized models for wound healing research in rodents.

Surface analytical studies of maxillofacial implants: influence of the preoperational treatment and the human body on the surface properties of retrieved implants

In the present work, surface analytical investigation of unimplanted as well as retrieved pyrolytic carbon-covered carbon/carbon composite implants and Ti osteosynthesis plates is reported. The Ti plates were covered by a 200-nm-thick, anodically and thermally formed TiO2 layer. Our results suggest that although the oxide layer on the Ti miniplates remained stable during the time spent in the human body, there is still material transport between the implant and the human body. In case of the carbon/carbon composite implants, damage of the carbon fibers constituting the material was found on one side of the sterile implant and attributed to the manufacturing process. The NaCl crystals originally present on the surface of the sterile material disappeared during the time spent in the human body. As a result of the interaction with the human body, a new surface layer (mainly constituted of carbon) appeared on the implant. The results indicate that both the time spent in the human organism and the preparation of the implants before operation can have detectable effects on the investigated surface properties. Surface analytical investigations could therefore provide information not only about the biocompatibility of these materials but also about the effect of their treatment before operation.

Are bioresorbable polylactate devices comparable to titanium devices for stabilizing Le Fort I advancement?

The purpose of this study was to evaluate whether skeletal and dental outcomes following Le Fort I surgery differed when stabilization was performed with polylactate bioresorbable devices or titanium devices. Fifty-seven patients with preoperative records and at least 1 year postoperative records were identified and grouped according to the stabilization method. All cephalometric X-rays were traced and digitized by a single operator. Analysis of covariance was used to compare the postsurgical change between the two stabilization methods. Twenty-seven patients received bioresorbable devices (group R), while 30 received titanium devices (group M). There were no statistically significant differences between the two groups with respect to gender, race/ethnicity, age, or dental and skeletal movements during surgery. Subtle postsurgical differences were noted, but were not statistically significant. Stabilization of Le Fort I advancement with polylactate bioresorbable and titanium devices produced similar clinical outcomes at 1 year following surgery.

Genotoxicity of Endosseous Implants Using Two Cellular Lineages In Vitro

The genotoxic potential of corrosion eluates obtained from a single dental implant using murine fibroblasts or osteoblasts cells in vitro by the single-cell gel (comet) assay was examined. A single commercially available dental implant (Biotechnology) was eluted in a solution consisting of equal amounts of acetic acid and sodium chloride (0.1 M) for 1, 3, 7, 14, and 21 days. Murine fibroblast or osteoblast cultures were then exposed to all corrosion eluates obtained from endosseous dental implants for 30 minutes at 37°C. The results suggest that none of the eluates produced genotoxic changes in murine fibroblasts regardless of the length of exposure to the eluate. Similarly, no genotoxicity was found in osteoblasts. The results suggest that the dental implant eluates tested in this study did not induce genetic damage as depicted by the single-cell gel (comet) assay. Because DNA damage is an important event during oncogenesis, this study represents a relevant contribution to estimate the real risks to the cellular system induced by the corrosion products of a dental implant.

Peculiarities of employment of polymeric miniplates for mandibular osteosynthesis: a preliminary study

Searching for new materials for bone substitution, fixation, and reconstruction is a challenging task that attracts scientists and researchers of different fields of medicine. During the last few decades, much interest has been paid to polymeric materials, polyethylene in particular. The aim of this study is to present generalizations about our own experience in the employment of polyethylene miniplates for the surgical treatment of mandibular fractures. Ninety patients with 139 uni- and bilateral mandibular fractures in different locations were involved. Treatment modalities included open reduction and internal fixation with self-made polyethylene miniplates of straight, T-shaped, Y-shaped, and X-shaped configurations and titanium screws. In 88 (97.8%) cases of surgical treatment of mandibular fractures using polymer miniplates, good anatomical and functional results were achieved. Regardless of the necessity for improvement of some mechanical properties of polyethylene, the results obtained in our clinical investigation allow us to recommend polyethylene miniplates for routine practice.

Current requirements for polymeric biomaterials in otolaryngology

In recent years otolaryngology was strongly influenced by newly developed implants which are based on both, innovative biomaterials and novel implant technologies. Since the biomaterials are integrated into biological systems they have to fulfill all technical requirements and accommodate biological interactions. Technical functionality relating to implant specific mechanical properties, a sufficiently high stability in terms of physiological conditions, and good biocompatibility are the demands with regard to suitability of biomaterials. The goal in applying biomaterials for implants is to maintain biofunctionality over extended periods of time. These general demands to biomaterials are equally valid for use in otolaryngology. Different classes of materials can be utilized as biomaterials. Metals belong to the oldest biomaterials. In addition, alloys, ceramics, inorganic glasses and composites have been tested successfully. Furthermore, natural and synthetic polymers are widely used materials, which will be in the focus of the current article with regard to their properties and usage as cochlear implants, osteosynthesis implants, stents, and matrices for tissue engineering. Due to their application as permanent or temporary implants materials are differentiated into biostable and biodegradable polymers. The here identified general and up to date requirements for biomaterials and the illustrated applications in otolaryngology emphasize ongoing research efforts in this area and at the same time demonstrate the high significance of interdisciplinary cooperation between natural sciences, engineering, and medical sciences.

Biodegradable fixation for craniomaxillofacial surgery: a 10-year experience involving 761 operations and 745 patients

Patient acceptance, safety, and efficacy of poly-l/dl-lactic acid (PLLDL) bone plates and screws in craniomaxillofacial surgery are reported in this article. Included in the sample are 745 patients who underwent 761 separate operations, including more than 1400 surgical procedures (orthognathic surgery (685), bone graft reconstruction (37), trauma (191) and transcranial surgery (20)). The success (no breakage or inflammation requiring additional operating room treatment) was 94%. Failure occurred because of breakage (14) or exuberant inflammation (31). All breakage occurred at mandibular sites and the majority of inflammatory failure occurred in the maxilla or orbit (29), with only two in the mandible. Failures were evenly distributed between the two major vendors. PLLDL 70/30 bone plates and screws may be used successfully in a variety of craniomaxillofacial surgical applications. The advantages include the gradual transference of physiological forces to the healing bone, the reduced need for a second operation to remove the material and its potential to serve as a vehicle to deliver bone-healing proteins to fracture/osteotomy sites. Bone healing was noted at all sites, even where exuberant inflammation required a second surgical intervention.

Release of metals from osteosynthesis implants as a method for identification: post-autopsy histopathological and ultrastructural forensic study

Metal structures--especially of stainless steel, titanium and their alloys (biomaterials)--are widely used in orthopaedic practice and the subject of constant study in bioengineering and preventive medicine. This study presents the first experience of forensic research into the presence of permanent tissue variations around metal implants in various bone structures for the purpose of identification, with particular reference to skeletal remains or severely decomposed corpses in the absence of other identifying elements. The evaluation was conducted on 12 corpses who had undergone osteosynthesis intra-vitam, whose implants were still in place or had been removed, in comparison with five controls who had never undergone osteosynthesis. Bone fragments taken during autopsy were subjected to histopathological and scanning electron microscope-energy dispersive electroscopy examination in order to reveal and characterise any metal particles originating from osteosynthesis. The study enabled the discovery of intra-bone metal particles in tissues treated by osteosynthesis even in bone areas where the implants had been removed and even where there were no longer any radiological signs of their application. These results are therefore of considerable forensic importance, especially in the area of identification, providing a valid means of recognition beyond that of the well-established use of in situ metal implants.

Air gun pellet remaining in the maxillary sinus for 50 years: a relevant risk factor for the patient?

The authors report the case of a 62-year-old man referred to the department of oral and maxillofacial surgery because of a clinical suspicion of palate carcinoma. Incidentally, diagnostic radiology showed a metallic foreign body in the left maxillary sinus. Anamnestic data revealed that a shot from an air gun accidentally hit the patient's left cheek in 1957. The lead-containing air gun pellet was removed by endoscopic antrostomy and the diagnosis of squamous cell carcinoma was confirmed by histopathological examination. 50 years after the pellet's impact, toxicological blood analysis showed no increased blood lead level. It remains unclear whether the air gun pellet has a potential toxicological effect or is related to the development of the patient's oral carcinoma. In this context the article reviews the literature and discusses the necessity of removing metal-containing foreign bodies, the role of lead in chronic toxicity and its possible carcinogenic effect in humans.

Clinical implementation of a multidirectional, angular stable osteosynthesis system in maxillofacial traumatology

AIM

To investigate whether a multidirectional, angular stable osteosynthesis system is suitable for the treatment of mandibular fractures and to compare it with well established available systems.

MATERIAL AND METHODS

Following preliminary testing in an animal model, the multidirectional angular stable system TiFix 2.3 obtained from Litos (Hamburg, Germany) was utilised for internal fixation of 39 mandibular fractures. These involved four symphyseal fractures, 17 parasymphyseal, 16 of the angle of the mandible and two comminuted fractures. The surgical and postoperative course was closely scrutinised. Radiographs were taken after 6 months and all plates removed under local anaesthesia. Photographs were taken intraoperatively and the plates and surrounding soft tissues were salvaged for histological analysis. Additionally, these operations were compared with treatment of equivalent fractures which were treated with conventional, non-angular stable systems. The relative costs have also been evaluated.

RESULTS

In 33 of the 39 fractures one TiFix plate sufficed for osteosynthesis. The plate most often used was a 2-hole plate which was applied in 25 (55.5%) fractures, followed by the 4-hole plates used in 16 (35.5%) fractures. In two comminuted fractures, four 6-hole plates were used (9%). In 17 patients the operation lasted less than 30 min, in 20 patients less than 60 min, in two less than 120 min. In all cases, the operations were shorter, and due to the plates' dimensions fewer screws had to be used, thus reducing the costs.

DISCUSSION

This angular stable system enabled reduction of the amount of the implant material. Also reduced were the operation time and the cost of the procedure. Furthermore, in the future it will allow smaller access incisions and better preservation of the soft tissue integrity.

Effect of human organism on the oxide layer formed on titanium osteosynthesis plates: a surface analytical study

The question of whether or not to remove the titanium osteosynthesis plates used in maxillofacial surgery is not yet answered. These plates can be left a long time in the organism if there is no harmful interaction between the plates and the organism. The authors examined the properties of the surface oxide layers formed on osteosynthesis titanium plates by subsequent thermal and anodic oxidation, together with the properties of plates removed from patients after three years. Surface analytical method Secondary Ion Mass Spectroscopy (SIMS) was chosen. It was found that inside of the about 200-mum thick oxide on the original plates the concentration of impurities is much lower than near the oxide/titanium interface. On the surface of plates removed from the human body, a C (carbon), Ca (calcium) and P (phosphorus) enrichment was detected, suggesting a biological interaction between the organism and the plate. The passivating layer formed with thermal and anodic oxidation has not changed significantly in three years; it resisted to the corrosive effect of the human organism.

A retrieval study on morphological and chemical changes of titanium osteosynthesis plates and adjacent tissues

AIM

To examine (a) morphological and chemical changes of retrieved titanium osteosynthesis plates, (b) findings in adjacent soft tissues during plate removal and to evaluate possible correlations among the above-mentioned issues.

MATERIAL AND METHODS

Ninety-four osteosynthesis plates were retrieved, of which 60 were studied and evaluated (including the adjacent soft tissue) in more details, 4-36 months following osteosynthesis in 26 trauma cases, 12 orthognathic and 6 maxillofacial reconstructive cases. Selected clinical parameters during plate removal, were studied. Specialized laboratory methods including light and electron microscopy as well as spectrometry and X-ray microanalysis were used to analyse the retrieved material.

RESULTS

Plates showed major mechanical changes (scratches, scraping and deformation) without corrosion. Soft tissue inflammation-mainly mild and chronic-was found in 53 of 94 plates removed, a statistically significant percentage. Pigmented deposits in the soft tissues manifested only traces of titanium when analysed elementally. There was no statistically significant correlation between the laboratory findings of plates and tissues, or between plate morphology and clinical findings recorded.

CONCLUSIONS

According to the findings of this study, inflammation in tissues adjacent to osteosynthesis plates should not be attributed to mechanical changes in the plates. Pigmented tissue deposits were neither found to be titanium to the extent previously reported, nor were they correlated with tissue inflammation. These findings lead to the assumption that titanium plates do not have to be removed to avoid local inflammatory problems.

Genotoxicity of Corrosion Eluates Obtained From Endosseous Implants

PURPOSE

Commercially pure titanium alloys are currently used as metallic biomaterials in implantology. Corrosion phenomena appear to play a decisive role in metallic implant long-term behavior. Thus, the goal of this study was to examine the genotoxic potential of corrosion eluates obtained from dental implants using Chinese ovary hamster cells in vitro by the single-cell gel (comet) assay. This technique detects deoxyribonucleic acid strand breaks in individual cells in alkaline conditions.

MATERIALS AND METHODS

The materials tested included 3 dental implants commercially available. Each of the tested materials was corroded in a solution consisting of equal amounts of acetic acid and sodium chloride (0.1 M) for 1, 3, 7, 14, and 21 days. The Chinese ovary hamster cultures were then exposed to all corrosion eluates obtained from endosseous dental implants for 30 minutes at 37 degrees C.

RESULTS

None of the eluates was found to exhibit genotoxicity, regardless of the type of dental implant used.

CONCLUSION

The results suggest that all dental implants tested in this study did not induce deoxyribonucleic acid breakage as depicted by the single-cell gel (comet) assay.

Plate removal in traumatic facial fractures: 13-year practice review

Various complications can result from titanium plate internal fixation, including infection, exposure, pain, cold intolerance, and palpability. The incidence of such complications has become a topic of recent interest with the advent of resorbable plating. We undertook a retrospective review to determine complication rates of titanium fixation in a facial fracture population. Out of 266 patients with operative management of traumatic facial fracture between 1991 and 2004, 135 patients had titanium plate fixation. We evaluated 16 panfacial fractures, 22 zygomatic-orbital complex fractures, 49 midface fractures, and 48 fractures of the mandible. Overall, 33.3% (45/135) of patients had plates removed; 64.4% (29/45) of plate removals were for complications, ie, discomfort, exposure, and infection; 35.6% (16/45) were removed during secondary reconstruction. The most common complication was discomfort related to palpability, cold intolerance, and pain. This constituted 72.4% (21/29) of all plate removals for complications. Higher rates of plate discomfort were noted near the supraorbital, infraorbital, and mental foramina.

Self-reinforced biodegradable screw fixation compared with titanium screw fixation in mandibular advancement

PURPOSE

This report compares the skeletal stability and treatment outcomes of 2 similar cohorts undergoing bilateral sagittal osteotomies of the mandible for advancement. The study groups included patients stabilized with 2-mm self-reinforced polylactate (PLLDL 70/30), biodegradable screws (group B), and 2-mm titanium screws placed in a positional fashion (group T).

MATERIALS AND METHODS

Sixty-nine patients underwent bilateral sagittal osteotomies of the mandibular ramus for advancement utilizing an identical technique. There were 34 patients in group B and 35 patients in group T. Each patient had preoperative, immediate postoperative, splint out, and 1-year postoperative cephalometric radiographs available for analysis. The method of analysis and treatment outcomes parameters are identical to those previously used. Repeated measures analysis of variance was performed with means of fixation as the between-subject factor and time as the within subject factor. The level of significance was set at .01.

RESULTS

There were no clinical failures in group T and a single failure in group B. The average difference in stability between the groups is small and subtly different at the mandibular angle. The data documented similarity of the postsurgical changes in the 2 groups with the only statistically significant difference being the vertical position of the gonion (P < .001) and the mandibular plane angle (P < .01) with greater upward remodeling at gonion in group T.

CONCLUSIONS

Two-mm self-reinforced PLLDL (70/30) screws can be used as effectively as 2-mm titanium screws to stabilize the mandible after bilateral sagittal osteotomies for mandibular advancement. The difference in 1-year stability and outcome is minimal.

Release of elements from retrieved maxillofacial plates and screws

Vitallium appliances and surrounding tissues were investigated to evaluate the release and accumulation of elements. Four microplates, sixteen screws and surrounding tissues were removed from three patients presenting inflammation 4 to 6 years after surgery and were submitted to SEM and X-ray microprobe analysis. Histology was performed on paraffin or PMMA sections of tissues.A continuous release of elements from metallic appliances into soft tissues was observed. Cobalt, chromium, and nickel were detected in soft and boney tissues in close proximity to the appliance. Aluminium, as a component of screw coatings, accumulated in soft tissues, and a remarkable amount of aluminium was detected in the dense lamella of lamellar bone. The results suggest that coatings containing aluminium should be avoided and the time these appliances are allowed to remain in patients should be shortened. Further studies on element release and the fate of aluminium in bone are warranted.

Surface Analysis Methods of Biomaterials Used in Oral Surgery: Literature Review

Titanium is the most frequently used biomaterial in oral surgery because of its positive physical and chemical properties. Clinical studies proved that the properties of titanium can be improved by surface modification techniques. To study the surface of biomaterials, the positive effects of the coatings, the response of the organism (corrosion resistance, physical and chemical stability, the thickness of various coatings, biocompatibility), one must choose and use the adequate analytical method for one's goal. In this article, the authors present the most frequently used analytical methods for the study of the surface morphology and composition of biomaterials. Also, they outline the advantages and disadvantages of specific analytical methods and the field where they are used.

Tissue response to poly-L-lactide acid-polyglycolic acid absorbable screws in autogenous bone grafts: a histologic morphological analysis

OBJECTIVES

To evaluate the local bone condition of autogenous chin grafts in contact with resorbable polymers fixation devices.

MATERIAL AND METHODS

Seven patients presenting severe maxillary and mandibular atrophy underwent alveolar ridge reconstruction with autogenous chin grafts fixed with conventional metallic screws, who received poly L-lactide acid-polyglycolic acid and titanium test screws for histological evaluation after 4 months of implantation.

RESULTS

Viable bone tissue could be seen in the specimens related to titanium test screws, with no signs of bone resorption or inflammation. A thick layer of fibrous connective tissue was observed between the resorbable test screws and bone tissue, which presented a few areas of resorption.

CONCLUSION

There are no contraindications of both materials for use as fixation devices in autogenous bone grafts. However, care must be taken when using absorbable screws in a period of 4 months, which can interfere with the sequence of the treatment with endosseous dental implants.

Closing anterior open bites by intruding molars with titanium miniplate anchorage

The intent of this study was threefold: (1) to validate true intrusion of molars in adults, (2) to test the stability of miniplates as anchorage for intruding posterior teeth in the maxilla, and (3) to record the skeletal and dental changes of open-bite closure. Four adult patients who had anterior open-bite malocclusions were selected to undergo posterior intrusion with miniplate anchorage to close the open bite; all had true intrusion of the maxillary molars. Mean molar intrusion was 1.99 mm (range, 1.45-3.32 mm). No movement of miniplates occurred at any time during their use or before intentional clinical removal. Open-bite closure was achieved for all 4 patients. Mean closure of incisors was 3.62 mm (range, 3.0-4.5 mm) as the mandibular plane closed 2.62 degrees (range, 1.5 degrees -4.5 degrees ), and the occlusal plane decreased 2.25 degrees (range, 1.0 degrees -3.5 degrees ). Anterior facial heights decreased as the mandible closed and B-point rotated anteriorly and upward.

Surface analysis of titanium maxillofacial plates and screws retrieved from patients

This investigation is a controlled human plate-retrieval study. The surface appearances and elemental composition of 50 titanium maxillofacial plates and associated screws retrieved from 39 patients were compared with a control sample of unused plates and screws using stereomicroscopy, scanning electron microscopy and energy dispersive X-ray analysis. There were two surface finishes, either anodized or non-anodized. Surface contamination was detected on both retrieved and control plates consisting of aluminium and silica and was more commonly present on non-anodized specimens. Manufacturing defects comprising rough metal edges and protuberances were identified on the unused controls and surgical damage was evident on the retrieved specimens. There were no signs of corrosion or surface deterioration on the retrieved plates and screws which had been in the tissues for between 1 month and 13 years. There was no evidence from this study to support the routine removal of titanium maxillofacial miniplates plates due to corrosion up to a period of 13 years.

Removal of titanium plates coated with anodic titanium oxide ceramic: retrospective study

Transformation of the surface of metallic titanium with titanium oxides prepared in various ways is a modern procedure. For more than 15 years, the authors have been utilizing fixing elements coated with titanium oxide ceramics, prepared by anodic oxidation and thermal treatment, for purposes of jawbone osteosynthesis. The aim of the authors' work was to assess the extent to which the titanium oxide ceramic coating influences the fate of the plates used for osteosynthesis within the human organism, in regard to the possible need for their removal. During a 5-year period, 108 of 1,396 plates coated with anodic titanium oxide had to be removed for various reasons: plate exposure (47), osteomyelitis (25), palpable swelling and tenderness (21), patient request for psychological reasons (13), or fracture of the plate (2). In none of these 108 cases was metallosis observed, which otherwise is reported relatively frequently in the vicinity of traditional titanium fixing elements, nor was any tissue damage connected with the surface of the plates. The results indicate the favorable properties of the titanium oxide ceramic surface.

A novel osteosynthesis plate design for routine corrective facial surgery

Plating systems for the osteosynthesis of facial osteotomies have different requirements to those used to treat facial fractures. The aim of fracture treatment is anatomical fragment reduction, functional/rigid immobilization, restoration of occlusion and aesthetics, and occasionally defect bridging. In corrective facial surgery however there is a need for intra-operative adjustments related to changes in occlusion and aesthetics, and defect bridging occurs frequently. Postoperatively, training elastics are used to control temporary neuromuscular imbalance. To accommodate these demands a new plating system is presented, based on five requisites: allowance of occlusal and aesthetic adjustment without hardware removal, plate dimensions that accommodate routine skeletal repositionings, reduced hardware volume compared with trauma plating systems, screws that fit the inter-dental spaces when tension banding, and capability for micro-screw fixation of bone grafts in the osteotomy site. The files of 1000 non-congenital facial deformity patients were analyzed. The sagittal, vertical and transverse movements were drawn and the bridging distances calculated. Slotted plates with double-armed interconnections were designed for maxillary, zygomatic-sandwich, chin and segmental osteotomies. A separate design was made for the sagittal split plate. A pilot study was performed using 20 patients. The system showed great versatility and adaptability, but a multicenter morbidity study is necessary, mainly to study postoperative stability.

The efficacy of resorbable plates in head and neck reconstruction

OBJECTIVE/HYPOTHESIS

The advent of malleable macroporous resorbable plates has allowed the surgeon a greater range of reconstructive options and has decreased the morbidity of conventional plating procedures. Completely malleable after warming to 55 degrees C, resorbable plates can readily conform to most morphologic appearances of fractures or defects and provide rigid fixation when cooled. The plating systems used in head and neck reconstruction are described.

STUDY DESIGN

Nine patients were selected for reconstruction using a resorbable plating system. The resorbable system was tested under a variety of clinical situations including frontal sinus fractures (three patients), midface fractures (two patients), mandibular defects (two patients), and laryngeal fractures (two patients).

METHODS

Each case was evaluated for rigidity of fixation, and ease of plate contouring and application. Furthermore, the postoperative functional and cosmetic results and complications were contrasted between the resorbable plating systems and each surgeon's vast experience with traditional plating systems.

RESULTS

The resorbable plating system was found to be as effective as traditional plating systems with respect to rigidity of fixation, functional results, and complications. In addition, the resorbable system was far easier to contour and, consequently, to apply, while producing higher cosmetic satisfaction after plate resorption than traditional plating.

CONCLUSIONS

Based on our experience, resorbable plates appear to be safe, easy to contour and apply, as well as effective for a wide range of head and neck reconstructive applications. In addition, the shortcomings of permanently retained plates such as plate migration, bone growth restriction, and imaging artifact are avoided.

Tissue changes adjacent to titanium plates in patients

INTRODUCTION

Titanium miniplates are widely used for osteosynthesis in maxillofacial surgery. Titanium is considered to be well tolerated but the long-term effects of titanium retained within human tissues are unclear.

AIMS

This study was designed to evaluate histomorphologically the soft tissues adjacent to titanium maxillofacial miniplates and screws in patients, and to determine the nature of pigmented, particulate debris found in the tissues.

MATERIALS

Thirty-five soft tissue specimens were excised from the tissues adjacent to titanium miniplates which had been in situ for between 1 month and 13 years.

METHODS

All of the soft tissue specimens were prepared for examination under the light microscope. Four specimens were examined under the scanning electron microscope and the transmission electron microscope. Energy dispersive X-ray analysis (EDX) was used to confirm the elemental composition of the particles under investigation.

RESULTS

All of the soft tissues showed fibrosis. Pigmented debris was present in 70% of the specimens and titanium was identified by EDX analysis. The debris was predominantly extra-cellular and was not associated with any inflammatory response or giant cell reaction. Fibroblasts were the predominant cell with small aggregates of lymphocytes and scattered macrophages.

CONCLUSION

Titanium is apparently well tolerated for up to 13 years.

Dynamic study about metal release from titanium miniplates in maxillofacial surgery

It has been shown that titanium (Ti) has had dramatic success in many surgical procedures as a result of its excellent mechanical properties and resistance to corrosion. There is still concern, however, about the release of metal and controversy surrounding whether or not the plates should be removed after bone healing. This study has been conducted to investigate whether or not there is a relationship between duration of plating and metal release from Ti miniplates in maxillofacial surgery. A prospective cohort study design was used. The concentration of Ti, in the soft tissues covering the plates, was examined in all patients who underwent removal of Ti miniplates from January 1998 to April 1999 (51 cases). Inductively Coupled Plasma-Optical Emission Spectrometry was used to measure Ti. Total ti and soluble Ti levels were compared to duration of plating (ranged from 15 days to 3 years, mean = 8 months). Correlation coefficients and two-way ANOVA were data processed. The average amount of total Ti in the soft tissues surrounding the plates was 1306 micrograms/g dry tissue. The mean of soluble Ti was 0.53 microgram/g dry tissue. The results of this study do not support the existence of a relationship between duration of plating and total Ti (correlation coefficient = 0.093 (P > 0.1) nor soluble Ti (correlation coefficient = 0.009 (P > 0.1) in the soft tissue surrounding the plates. Moreover, the only independent factor of Ti release found was associated with mechanical constraints during surgery. Almost 100% of Ti is released during the osteosynthesis. Then Ti levels remain constant in the surrounding tissues. Most of the time, Ti seems to be clinically inert. Compared to the possible risks of a second operation, removal of Ti miniplates should not be a routine procedure except in the case of complaints from patients, particularly in the case of infection, hypersensitivity, dehiscence or screw loosening.