Immuno-inflammatory responses in the tissue adjacent to titanium miniplates used in the treatment of mandibular fractures

Frequency and Reasons for Fixation Hardware Removal After Orthognathic Surgery in Patients Treated in One Center

Background and Objectives: Despite the well-established position of orthognathic surgery as a field of surgical treatment of deformities within the facial skeleton, it has not been possible to develop unanimous recommendations on how to approach fixation hardware after the healing period. In the absence of clear guidelines from opinion leaders and scientific societies on how to approach osteosynthesis after surgery, the decision to leave or remove fixation hardware is made individually by treatment centers, mostly based on their own experience. It is also important whether or not surgical procedures are financed by public funds. This issue extends beyond orthognathic surgery, affecting all facial skeleton procedures involving osteosynthesis materials. The aim of this study is to analyze the frequency and reasons for fixation hardware removal after orthognathic surgery in patients treated in one center. Materials and Methods: This retrospective study examined the medical records from 2015 to 2020 of patients treated surgically for skeletal deformities at the Department and Clinic of Otolaryngology and Maxillofacial Surgery of Collegium Medicum (formerly the Otolaryngology Department of the Provincial Hospital in Zielona Góra). This study analyzed the age and sex of patients, the type of orthognathic procedure, and the type of skeletal deformity, as well as the reasons for fixation hardware removal in the groups of patients. Results: During this period, 124 orthognathic procedures were performed, including 56 one-jaw operations (BSSO or Le Fort I maxillary osteotomy), 2 one-jaw operations with genioplasty, 55 bimaxillary operations (BSSO + Le Fort I maxillary osteotomy), 6 bimaxillary surgery with genioplasty and 5 isolated genioplasty procedures. Fixation hardware was removed in 77 cases (62.10% of procedures), comprising 57 women and 20 men. Reasons for osteosynthesis removal were divided into three groups: complications such as the occurrence of inflammatory reaction/infection (n = 17), subjective discomfort (n = 23), and patient requests (n = 37). Conclusions: The findings underscore the need for scientific societies to establish unified guidelines on managing post-surgical fixation hardware to standardize care and enhance patient outcomes.

Cross-Sectional Study of Serum Metal Ions in Patients With Metal Implants in the Maxillofacial Region

Purpose

The purpose of the present study was to measure the serum metal ion levels (titanium, cobalt, chromium) in patients who have metal implants in the maxillofacial region.

Methods

The investigators implemented a cross sectional study on patients treated with procedures requiring metal implants for management of maxillofacial trauma, fixation for orthognathic surgery, and total temporomandibular joint replacement (TJR). Inductively coupled plasma mass spectrometry was used as an analytical method to detect metal ions in serum samples.

Results

The study comprised of 50 patients who were divided into 4 groups- group I- total TJR (n = 18), group II- orthognathic (n = 8), group III- trauma (n = 8), and group IV- control (n = 16). The mean values of metal ions level were raised than the control group.

Conclusion

The present study's results suggest a rise in serum metal ion levels after the metal implantation in maxillofacial region. None of the patients had any abnormal signs and symptoms due to raised metal levels. Further studies are warranted to correlate the serum metal ion levels and their clinical relevance.

Titanium Internal Fixator Removal in Maxillofacial Surgery: Is It Necessary? A Systematic Review and Meta-Analysis

Titanium plates and screws are essential devices in maxillofacial surgery since late 1980s, but despite their wide use there is no consensus in titanium internal fixators removal after bone healing. A systematic literature review and meta-analysis were conducted on seventeen retrospective studies. Effect size and 95% confidence intervals were calculated for plate removal (per plate and per patient) and for removal causes (infection, pain, screws complications, exposition, palpability). Odds ratio, 95% confidence intervals, and χ 2 test were measured for sex, smoking, and implant site. Heterogeneity was evaluated with Cochran and Inconstancy test. Obtained data were used to design Forest and Funnel plots. The aim of the study is to identify and clarify reasons and risk factors for plates and screws removal. Infection is the most frequent reason; the habit of tobacco usage and implant site (mandibula) are the main risk factors. The administration of antibiotic prophylaxis is essential, and patients must quit smoking before and after surgery. In conclusion there is no scientific evidence supporting the removal of internal devices as mandatory step of the postoperative procedure.

Resorbable Versus Titanium Rigid Fixation for Pediatric Mandibular Fractures: A Systematic Review, Institutional Experience and Comparative Analysis

Study Design

Pediatric mandible fractures mandate special consideration because of unerupted teeth, mixed dentition, facial growth and the inability to tolerate maxillomandibular fixation. No consensus exists as to whether resorbable or titanium plating systems are superior with regards to clinical outcomes.

Objective

This study aims to systematically review and compare the outcomes of both material types in the treatment of pediatric mandible fractures.

Methods

After PROSPERO registration, studies from 1990-2020 publishing on outcomes of ORIF of pediatric mandible fractures were systematically reviewed according to PRISMA guidelines. An additional retrospective review was conducted at a pediatric level 1 trauma center.

Results

1,144 patients met inclusion criteria (30.5% resorbable vs. 69.5% titanium). Total complication rate was 13%, and 10% required a second, unplanned operation. Complication rates in the titanium and resorbable groups were not significantly different (14% vs. 10%; P = 0.07), and titanium hardware was more frequently removed on an elective basis (P < 0.001). Condylar/sub-condylar fractures were more often treated with resorbable hardware (P = 0.01); whereas angle fractures were more often treated with titanium hardware (P < 0.001). Within both cohorts, fracture type did not increase the risk of complications, and comparison between groups by anatomic level did not demonstrate any significant difference in complications.

Conclusions

Pediatric mandible fractures requiring ORIF are rare, and hardware-specific outcomes data is scarce. This study suggests that titanium and resorbable plating systems are equally safe, but titanium hardware often requires surgical removal. Surgical approach should be tailored by fracture anatomy, age-related concerns and surgeon preference.

Biocompatible Materials for Orbital Wall Reconstruction-An Overview

The reconstruction of an orbit after complex craniofacial fractures can be extremely demanding. For satisfactory functional and aesthetic results, it is necessary to restore the orbital walls and the craniofacial skeleton using various types of materials. The reconstruction materials can be divided into autografts (bone or cartilage tissue) or allografts (metals, ceramics, or plastic materials, and combinations of these materials). Over time, different types of materials have been used, considering characteristics such as their stability, biocompatibility, cost, safety, and intraoperative flexibility. Although the ideal material for orbital reconstruction could not be unanimously identified, much progress has been achieved in recent years. In this article, we summarise the advantages and disadvantages of each category of reconstruction materials. We also provide an update on improvements in material properties through various modern processing techniques. Good results in reconstructive surgery of the orbit require both material and technological innovations.

In Silico Biomechanical Evaluation of WE43 Magnesium Plates for Mandibular Fracture Fixation

Titanium fixation devices are the gold standard for the treatment of mandibular fractures; however, they present serious limitations, such as non-degradability and generation of imaging artifacts. As an alternative, biodegradable magnesium alloys have lately drawn attention due to their biodegradability and biocompatibility. In addition, magnesium alloys offer a relatively high modulus of elasticity in comparison to biodegradable polymers, being a potential option to substitute titanium in highly loaded anatomical areas, such as the mandible. This study aimed to evaluate the biomechanical competence of magnesium alloy WE43 plates for mandibular fracture fixation in comparison to the clinical standard or even softer polymer solutions. A 3D finite element model of the human mandible was developed, and four different fracture scenarios were simulated, together with physiological post-operative loading and boundary conditions. In a systematic comparison, the material properties of titanium alloy Ti-6Al-4V, magnesium alloy WE43, and polylactic acid (PLA) were assigned to the fixation devices, and two different plate thicknesses were tested. No failure was predicted in the fixation devices for any of the tested materials. Moreover, the magnesium and titanium fixation devices induced a similar amount of strain within the healing regions. On the other hand, the PLA devices led to higher mechanical strains within the healing region. Plate thickness only slightly influenced the primary fixation stability. Therefore, magnesium alloy WE43 fixation devices seem to provide a suitable biomechanical environment to support mandibular fracture healing in the early stages of bone healing. Magnesium WE43 showed a biomechanical performance similar to clinically used titanium devices with the added advantages of biodegradability and radiopacity, and at the same time it showed a remarkably higher primary stability compared to PLA fixation devices, which appear to be too unstable, especially in the posterior and more loaded mandibular fracture cases.

Is titanium-zirconium alloy a better alternative to pure titanium for oral implant? Composition, mechanical properties, and microstructure analysis

Introduction

Titanium (Ti) is widely accepted as a biomaterial for orthopaedic and dental implants, primarily due to its capacity to integrate directly into the bone and its superior corrosion resistance. It has been suggested that titanium–zirconium alloy (TiZr), with 13–17% of zirconium, has better mechanical properties than pure Ti, but there are very few published studies assessing the suitability of TiZr for high-load- bearing implants. This study aimed to compare the mechanical properties and microstructures of TiZr and commercially pure titanium (Ti).

Methodology

Pure Ti and TiZr alloy discs were prepared and subjected to characterisation by nanoindentation, electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD).

Results

The TiZr alloy was found to have significantly lower elastic modulus value (p < 0.0001) and greater hardness than Ti (p < 0.05). The EDS results confirmed the presence of Zr (13–17%) in the TiZr alloy, with XRD and EBSD images showing microstructure with the alpha phase similar to commercially available Ti.

Conclusion

The lower elastic modulus, higher hardness, presence of alpha phase, and the finer grain size of the TiZr alloy make it more suitable for high-load-bearing implants compared to commercially available Ti and is likely to encourage a positive biological response.

Benefits and Biosafety of Use of 3D-Printing Technology for Titanium Biomedical Implants: A Pilot Study in the Rabbit Model

BACKGROUND

Titanium has been used in osteosynthesis for decades and its compatibility and safety is unquestioned. Studies have shown that there is release and collection of titanium in the organ systems with little note of toxicity. The gold standard is considered to be titanium osteosynthesis plate produced by milling methods. The use of customized titanium plates produced with 3D printing, specifically direct metal laser sintering, have found increasing use in recent years. It is unknown how much titanium is released in these printed titanium implants, which is known to be potentially porous, depending on the heat settings of the printer. We hypothesize that the amount of titanium released in printed titanium implants may be potentially more or equal compared to the gold standard, which is the implant produced by milling.

METHODS

We studied the biosafety of this technology and its products by measuring serum and organ titanium levels after implantation of 3D-printed versus traditionally fabrication titanium plates and screws in a pilot study using the rabbit model. A total of nine rabbits were used, with three each in the control, milled and printed titanium group. The animals were euthanized after six months. Serum and organs of the reticuloendothelial system were harvested, digested and assayed for titanium levels.

RESULTS

Organ and serum titanium levels were significantly higher in rabbit subjects implanted with titanium implants (milled and printed) compared to the control group. However, there was no significant difference in organ and serum titanium levels of subjects implanted with milled and traditionally fabricated titanium implants.

CONCLUSIONS

The biosafety of use of 3D-printed titanium implants and traditionally fabricated titanium implants are comparable. With this in mind, 3D-printed custom implants can not only replace, but will very possibly surpass traditionally fabricated titanium implants in the mode and extent of use.

Titanium and Other Metal Hypersensitivity Diagnosed by MELISA® Test: Follow-Up Study

This study is aimed at proving the clinical benefit of the MELISA® test in the minimization or complete elimination of health problems in patients with confirmed hypersensitivity to metals used for tissue replacements. A group of 305 patients aged 20-75 years with previously proven metal hypersensitivity (initial MELISA® test), mainly to titanium and then to another fifteen metals, was chosen from the database at the Institute of Dental Medicine. From these patients, a final group of 42 patients agreed to participate in the study, 35 of which were female and 7 were male. The patients completed a special questionnaire aimed at information regarding change of health status from their last visit and determining whether the results of the initial MELISA® test and recommendations based on it were beneficial for patients or not. They were clinically examined, and peripheral blood samples were taken to perform follow-up MELISA® tests. Questionnaire data was processed, and the follow-up MELISA® test results were compared with the results of the initial MELISA® tests. For statistical analysis, the Fisher's exact test and paired T-test were used. Thirty-two patients reported that they followed the recommendations based on the results of the initial MELISA® tests, and of these, 30 patients (94%) confirmed significant health improvement. Six patients did not follow the recommendation, and from these, only one patient reported an improvement in his health problems. By comparison of the initial and follow-up MELISA® test results, it can be stated that the hypersensitivity to the given metal decreased or disappeared after the therapeutic interventions performed based on the initial MELISA® test results. The evaluation of the data obtained from patients in this study confirmed a significant clinical benefit of MELISA® test.

Resorbable Versus Titanium Hardware for Rigid Fixation of Pediatric Upper and Midfacial Fractures: Which Carries a Lower Risk Profile?

PURPOSE

Titanium associated risks have led to interest in resorbable hardware for open reduction and internal fixation (ORIF) of pediatric facial fractures. This study aims to systematically review and compare the outcomes of titanium/resorbable hardware used for ORIF of upper/midfacial fractures to determine which hardware carries a higher complication rate in the pediatric patient.

METHODS

Studies published between 1990 and 2020 on the ORIF of pediatric upper/midfacial fractures were systematically reviewed. A retrospective institutional review was also conducted, and both arms were compiled for final analysis. The primary predictor value was the type of hardware used and the primary outcome was the presence of a complication. Fisher's exact test and 2-proportion 2-tailed z-test calculations were used to determine statistical significance, which was defined as a P value < .05. The low quality of published evidence precluded meta-analysis.

RESULTS

Systematic review of 23 studies identified 659 patients, and 77 patients were identified in the institutional review. A total of 736 patients (299 resorbable, 437 titanium) were included in the final analysis. Total complication rate was 22.8%. The titanium group had a higher complication rate (27 vs 16.7%; P < .01), and more often underwent elective hardware removal (87.3 vs 0%, P < .01). In each hardware subgroup, the incidence of complications was analyzed by fracture site. In the titanium group, complication incidence was higher when treating maxillary fractures (32.8 vs 22.9%, P = .03). When comparing the 2 hardware groups by fracture site, maxillary fractures had a higher rate of complications when treated by titanium hardware compared with resorbable hardware (32.8 vs 18%, P < .01).

CONCLUSIONS

Upper/midfacial pediatric fractures requiring ORIF, especially maxillary fractures, may be best treated with resorbable hardware. Additional hardware-specific outcomes data is encouraged.

An improved process for the fabrication and surface treatment of custom-made titanium cranioplasty implants informed by surface analysis

Cranioplasty implants are routinely fabricated from commercially pure titanium plates by maxillofacial prosthetists. The differing fabrication protocols adopted by prosthetists working at different hospital sites gives rise to considerable variations in surface topography and composition of cranioplasty implants, with residues from the fabrication processes having been found to become incorporated into the surface of the implant. There is a growing recognition among maxillofacial prosthetists of the need to standardise these protocols to ensure quality and consistency of practice within the profession. In an effort to identify and eliminate the source of the inclusions associated with one such fabrication protocol, the present study examined the surfaces of samples subjected to each of the manufacturing steps involved. Surface and elemental analysis techniques identified the main constituent of the surface inclusions to be silicon from the glass beads used to texture the surface of the implant during fabrication. Subsequent analysis of samples prepared according to a revised protocol resulted in a more homogeneous titanium dioxide surface as evidenced by the reduction in area occupied by surface inclusions (from 8.51% ± 2.60% to 0.93% ± 0.62%). These findings may inform the development of improved protocols for the fabrication of titanium cranioplasty plates.

Evaluation of insertion torque and surface integrity of zirconia-coated titanium mini screw implants

INTRODUCTION

The aim of this study was to devise a modification of a temporary anchorage device (TAD) by coating titanium mini screw implants with yttrium stabilized zirconia and to evaluate the insertion torque and surface integrity of it.

METHOD

Five titanium implants (Absoanchor, Dentos, South Korea) from each of the four groups comprising of 6 SH 13-08, 6 SH 13 -10 cylindrical and 6 SH 1312-08, 6 SH 1312-10 tapered mini screw implants were selected to be in the experimental group (Zr Ti) of implants, wherein they were coated with yttrium stabilised zirconia using a RF/DC magnetron sputtering unit. One mini screw implant from each of the four groups remained without coating to serve as control (Ti). After the coating of the titanium mini screw implants, scanning electron microscope (SEM) study was performed to evaluate the thickness and uniformity of the coating obtained. The insertion torque of all implants were evaluated by inserting the implant into bone sample using a manual torque wrench (ADIN). The implants were retrieved from the bone sample and a post insertion SEM study was performed to evaluate any changes in the surface of the Zr-Ti and Ti implants. X-ray diffraction (XRD) analysis was done to confirm the presence of Zirconia in the implants from the experimental group.

RESULTS

There was no statistically significant difference between the insertion torque for the zirconia coated mini screw implants and the titanium mini screw implants, where the P value < 0.05 was considered as statistically significant. The values for insertion torque for Zr Ti cylindrical group of 8 mm length ranged from 19-20 N-cm and that for the tapered group of 8 mm length ranged from 15-17 N-cm. The insertion torque for the Zr Ti tapered group of 8 mm ranged from 21-22 N-cm and that of the tapered group ranged from 16-18 N-cm.The insertion torque values for the Ti cylindrical implant for length of 8 mm was 20 N-cm and 21 N-cm for length of 10 mm. The insertion torque values for the Ti tapered implant was 15N-cm for 8 mm length and 16N-cm for 10 mm length.

CONCLUSION

The Zirconia coating on the Titanium mini screw implants was of 2.6 µm in thickness. There was no statistically significant difference in the insertion torque of the Zirconia coated mini screw implants and the non-coated titanium mini screw implants which retained their structural integrity.

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.

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.

Bioabsorbable magnesium versus standard titanium compression screws for fixation of distal metatarsal osteotomies - 3 year results of a randomized clinical trial

BACKGROUND

For the treatment of hallux valgus commonly distal metatarsal osteotomies are performed. Persistent problems due to the hardware and the necessity of hardware removal has led to the development of absorbable implants. To overcome the limitations of formerly used materials for biodegradable implants, recently magnesium has been introduced as a novel implant material. This is the first study showing mid-term clinical and radiological (MRI) data after using magnesium implants for fixation of distal metatarsal osteotomies.

MATERIAL AND METHODS

26 patients with symptomatic hallux valgus were included in the study. They were randomly selected to be treated with a magnesium or standard titanium screw for fixation of a modified distal metatarsal osteotomy. The patients had a standardized clinical follow up and MRI investigation 3 years' post-surgery. The clinical tests included the range of motion of the MTP 1, the AOFAS, FAAM and SF-36 scores. Further on the pain was evaluated on a VAS.

RESULTS

Eight patients of the magnesium group and 6 of the titanium group had a full clinical and MRI follow up 3 years postoperatively. One patient was lost to follow-up. All other patients could be interviewed, but denied full study participation. There was a significant improvement for all tested clinical scores (AOFAS, SF-36, FAAM, Pain-NRS) from pre-to postoperative investigation, but no statistically relevant difference between the groups. Magnesium implants showed significantly less artifacts in the MRI, no implant related cysts were found and the implant was under degradation three years postoperatively.

CONCLUSION

In this study, bioabsorbable magnesium implants showed comparable clinical results to titanium standard implants 3 years after distal modified metatarsal osteotomy and were more suitable for radiologic analysis.

LEVEL OF EVIDENCE

2.

The Clinical Feasibility of Newly Developed Thin Flat-Type Bioresorbable Osteosynthesis Devices for the Internal Fixation of Zygomatic Fractures: Is There a Difference in Healing Between Bioresorbable Materials and Titanium Osteosynthesis?

INTRODUCTION

In recent years, bioresorbable plates have undergone remarkable development. However, there has been no attendant improvement in their strength, because strength requires thickness, and complications such as palpability are related to the thickness of bioresorbable plate systems. In this clinical study, we compared the surgical management of zygomatic fractures using newly developed thinner bioresorbable materials or conventional titanium miniplates.

METHODS

Twelve patients with zygomatic fractures were randomly divided equally into 2 groups (6 with new bioresorbable osteosynthesis materials and 6 with standard titanium miniplates). Using computed tomography, we evaluated the thickness of the soft tissue and plate at the zygomaticofrontal sutures in each patient with the help of detailed radiographic computed tomography data at 6 months postoperatively. We compared the amount of soft-tissue volume increase between the uninjured healthy and injured operated sides in each patient.

RESULTS

Both groups eventually achieved satisfactory healing, with a favorable restoration of form and function and without any complications, including palpability. The amount of soft-tissue volume increase at the operated side relative to the uninjured healthy side using new thin bioresorbable plates was 131.1% (range: 101.5-165.8). On the other hand, that of titanium miniplates was 126.4% (range: 102.2-167.6). There was no statistically significant difference (P > 0.05).

CONCLUSION

This newly developed thinner flat-type bioresorbable plate system could be considered clinically useful in the treatment of zygomatic fractures even in easily palpated areas, such as the infraorbital rim or zygomaticofrontal sutures, without any healing differences in skeleton as compared with conventional titanium miniplates.

Biomaterials in Orthopedic Surgery: Effects of a Nickel-Reduced Stainless Steel on in Vitro Proliferation and Activation of Human Osteoblasts

A new austenitic stainless steel compound, P558, has been widely recognized to have good mechanical properties, excellent potential for corrosion resistance and negligible nickel ion release, making it a promising substitute for more expensive metallic prostheses with limited machinable features. The effect of P558 was studied in vitro and human osteoblast- like cells (MG63) were cultured directly on P558, Ti6Al4V alloy (Ti), and polystyrene (Control) for 72 hours. Osteoblast functions were evaluated by assaying cell proliferation and synthetic activity after 1.25(OH)2D3 stimulation. Results demonstrated that growth of MG63 on P558 was not negatively affected when compared to the Ti and Control groups and showed no alteration in the production of ALP, NO and PICP. Moreover, IL-6 was lower, whereas OC and TGFbeta1 were significantly higher. SEM images revealed that cells proliferated and differentiated on P558 without any alteration in their morphology. The current findings have demonstrated that P558 promotes osteoblast proliferation, activation and differentiation without negative effects and, thus, its good biocompatibility when used for orthopedic application.

Early results using a biodegradable magnesium screw for modified chevron osteotomies

This is the first larger study analyzing the use of magnesium-based screws for fixation of modified Chevron osteotomies in hallux valgus surgery. Forty-four patients (45 feet) were included in this prospective study. A modified Chevron osteotomy was performed on every patient and a magnesium screw used for fixation. The mean clinical follow up was 21.4 weeks. The mean age of the patients was 45.5 years. Forty patients could be provided with the implant, in four patients the surgeon decided to change to a standard metallic implant. The AOFAS, FAAM and pain NRS-scale improved markedly. The hallux valgus angle, intermetatarsal angle and sesamoid position improved significantly. Seven patients showed dorsal subluxation, rotation or medial shifting of the metatarsal heads within the first 3 months. One of these patients was revised, in all others the findings were considered clinically not significant or the patients refused revision. This study shows the feasibility of using magnesium screws in hallux valgus-surgery. Surgeons starting with the use of these implants should be aware of the proper handling of these implants and should know about corrosion effects during healing and its radiographic appearance. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2207-2214, 2016.

Tissue response to titanium implant using scanning electron microscope

Most of the surgeons now use titanium miniplates because of its biocompatibility and corrosion resistant properties; studies have shown that these titanium particles are released in the surrounding tissues causing tissue necrosis and if these implants are placed for a long period, the adverse effect of these implants are more severe. It therefore necessitates a study to find out whether these titanium particles are released into surrounding tissues from titanium miniplates used for maxillofacial fractures so that we could use these implants, that is, bone plates and screws with more confidence.

Treatment of malar and midfacial fractures with osteoconductive forged unsintered hydroxyapatite and poly-L-lactide composite internal fixation devices

PURPOSE

To evaluate the internal fixation of malar and midfacial fractures, long-term results, and biocompatibility of osteoconductive internal fixation devices composed of a forged composite of unsintered hydroxyapatite and poly-L-lactide (F-u-HA/PLLA).

MATERIALS AND METHODS

From January 2006 to June 2010, 29 patients (24 males and 5 females; age 33 ± 15 years) were included in the present prospective study. The fracture type was malar in 24 patients, midfacial in 5, isolated orbital floor blowout in 2, and frontal sinus, cranial base in 2 patients. The fractures were fixed with internal fixation devices; these were plates and screws composed of F-u-HA/PLLA. The 24 patients with malar fractures were treated with a single 4-hole L-plate or a straight plate at the infrazygomatic crest.

RESULTS

All fractures with internal fixation using devices composed of F-u-HA/PLLA healed well. All malar and midfacial fractures had satisfactory long-term stability. The follow-up examinations at 12 to 67 months after surgery showed that most patients had no complaints, although 2 patients (15%) had a foreign body reaction that was treated by implant removal, with complete symptom resolution. At 5 years after fracture fixation, 2 patients had ultrasound and 2 had radiographic evidence of residual material. An exemplar biopsy showed direct bone growth into the material.

CONCLUSIONS

In patients with malar and midfacial fractures, hardware composed of the F-u-HA/PLLA composite provided reliable and satisfactory internal fixation, intraoperative handling, long-term stability, and biocompatibility. Direct bone growth into the material could be histopathologically exemplified, in contrast to previous polymer fixations that were resorbed and surrounded by a connective tissue layer. This finding indicates that long-term F-u-HA/PLLA residual material will be included into the remodeled bone, which was confirmed on long-term follow-up radiographs.

An electrochemical investigation of TMJ implant metal alloys in an artificial joint fluid environment: the influence of pH variation

OBJECTIVE

To investigate the corrosion behaviour of commonly used TMJ implants alloys (CoCrMo and Ti6Al4V) under simulated physiological conditions.

METHODS

Corrosion behaviour was evaluated using standard electrochemical corrosion techniques and galvanic corrosion techniques as per ASTM standards. Standard electrochemical tests (E(corr), I(corr), R(p) and C(f)) were conducted in bovine calf serum (BCS), as a function of alloys type and different pHs. Galvanic corrosion tests were conducted in BCS at a pH of 7.6. Alloy surfaces were characterized using white-light interferometry (WLI) and scanning electron microscopy (SEM).

RESULTS

The potentiodynamic test results exhibited the enhanced passive layer growth and a better corrosion resistance of Ti6Al4V compared to CoCrMo. Electrochemical impedance spectroscopy measurements demonstrated the influence of protein as a function of pH on corrosion mechanisms/kinetics. Galvanic coupling was not a major contributor to corrosion. SEM and WLI images demonstrated a significantly higher in surface roughness in CoCrMo after corrosion.

CONCLUSIONS

The results of this study suggest that Ti6Al4V shows superior corrosion behaviour to CoCrMo due to its strong passive layer, simulated joint fluid components can affect the electrochemical nature of the metal/electrolyte interface as a function of pH, and the galvanic effect of coupling CoCrMo and Ti6Al4V in a single joint is weak.

Allergy related to dental implant and its clinical significance

The oral cavity provides an ideal and unique environment for study of biological processes involving metallic dental aids. Dental materials within the mouth interact continually with physiological fluids. Oral tissues are exposed to a veritable bombardment of both chemical and physical stimuli as well as the metabolism of many species of bacteria; yet, for the most part, oral tissues remain healthy. The pH of saliva varies from 5.2 to 7.8. Teeth, restorations, or any prosthesis including dental implants in the oral cavity have to function in one of the most inhospitable environments in the human body. They are subject to larger temperature and pH variations than most other parts of the body. Corrosion, the graded degradation of materials by electrochemical attack, is of concern particularly when dental implants are placed in the hostile electrolytic environment provided by the human mouth. Allergic reactions may occur from the presence of ions produced from the corrosion of implants. The present article describes various manifestations of allergic reactions due to implant material in the oral cavity.

Hypersensitivity to titanium: a less explored area of research

Titanium is considered as an excellent biocompatible metal and it is used in implant dentistry. Literature suggests that Ti can induce clinically relevant hypersensitivity and other immune dysfunctions in certain patients chronically exposed to this reactive metal. At the same time, no standard patch test for Ti has so far been developed, and positive reactions to Ti have therefore only rarely been demonstrated with skin testing. This article reports about the corrosion of dental implants, their significance when hypersensitivity is present, and the literature available till date regarding hypersensitivity of titanium.

Patients' preoperative expectations and postoperative satisfaction of dysgnathic patients operated on with resorbable osteosyntheses

BACKGROUND

This study evaluated whether personal expectations and satisfaction throughout orthognathic surgery were fulfilled. In addition, patients were interrogated about their experience of resorbable osteosynthesis.

METHODS

A total of 50 patients were interviewed 3 times each throughout the study by a mixed questionnaire of standard psychologic tests and a tailored itemized questionnaire regarding their expectations regarding resorbable osteofixation and their postoperative satisfaction.

RESULTS

A postoperative increase in self-esteem and approach to life were evident. An examination of Oral Health-Related Quality of Life showed constant quality of life; an examination of Oral Health Impact Profile-Germany) showed no postoperative difficulties in dental hygiene and nutrition. No statistically significant change in any of the tests could be expressly determined. Avoidance of secondary surgery motivated 94% to choose resorbable osteofixations, although a mere 66% had heard of them before; 90% of patients were satisfied with the operation result.

CONCLUSIONS

Orthognathic surgery cannot change preexistent depression or a problematic social background. Mastication and oral health improved, and postoperative happiness and confidence increased. When given the choice between resorbable fixation and titanium osteofixation, patients generally preferred resorbable fixations.

Comparison of morphological changes in efferent lymph nodes after implantation of resorbable and non-resorbable implants in rabbits

Background

Magnesium alloys as biodegradable implant materials received much interest in recent years. It is known that products of implant degradation can induce several types of immune response. Hence, the aim of this study was to examine the morphological changes of efferent lymph nodes after implantation of different resorbable magnesium alloys (MgCa0.8, LAE442) in comparison to commercially available resorbable (PLA) and non-resorbable (titanium) implant materials as well as control groups without implant material.

Methods

The different implant materials were inserted intramedullary into the rabbit tibia. After postoperative observation periods of three and six months, popliteal lymph nodes were examined histologically and immunhistologically and compared to lymph nodes of sham operated animals and animals without surgery. Haematoxylin and eosin staining was performed for cell differentiation. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection, mouse anti-CD68 primary antibodies for macrophage detection. Evaluation of all sections was performed applying a semi quantitative score.

Results

The histological evaluation demonstrated low and moderate levels of morphological changes for both magnesium alloys (LAE442 and MgCa0.8). Higher than moderate values were reached for titanium in sinus histiocytosis and histiocytic apoptosis (3 months) and for PLA in histiocytic apoptosis (3 and 6 months). The immune response to all investigated implants had a non-specific character and predominantly was a foreign-body reaction. LAE442 provoked the lowest changes which might be due to a lower degradation rate in comparison to MgCa0.8. Therewith it is a promising candidate for implants with low immunogenic potential.

Conclusion

Both examined magnesium alloys did not cause significantly increased morphological changes in efferent lymph nodes in comparison to the widely used implant materials titanium and PLA. LAE442 induced even lower immunological reactions. Therewith MgCa0.8 and especially LAE442 are appropriate candidates for biomedical use.

Biomaterials for craniofacial reconstruction

Biomaterials for reconstruction of bony defects of the skull comprise of osteosynthetic materials applied after osteotomies or traumatic fractures and materials to fill bony defects which result from malformation, trauma or tumor resections. Other applications concern functional augmentations for dental implants or aesthetic augmentations in the facial region. For ostheosynthesis, mini- and microplates made from titanium alloys provide major advantages concerning biocompatibility, stability and individual fitting to the implant bed. The necessity of removing asymptomatic plates and screws after fracture healing is still a controversial issue. Risks and costs of secondary surgery for removal face a low rate of complications (due to corrosion products) when the material remains in situ. Resorbable osteosynthesis systems have similar mechanical stability and are especially useful in the growing skull. The huge variety of biomaterials for the reconstruction of bony defects makes it difficult to decide which material is adequate for which indication and for which site. The optimal biomaterial that meets every requirement (e.g. biocompatibility, stability, intraoperative fitting, product safety, low costs etc.) does not exist. The different material types are (autogenic) bone and many alloplastics such as metals (mainly titanium), ceramics, plastics and composites. Future developments aim to improve physical and biological properties, especially regarding surface interactions. To date, tissue engineered bone is far from routine clinical application.

Titanium allergy: could it affect dental implant integration?

PURPOSE

Degradation products of metallic biomaterials including titanium may result in metal hypersensitivity reaction. Hypersensitivity to biomaterials is often described in terms of vague pain, skin rashes, fatigue and malaise and in some cases implant loss. Recently, titanium hypersensitivity has been suggested as one of the factors responsible for implant failure. Although titanium hypersensitivity is a growing concern, epidemiological data on incidence of titanium-related allergic reactions are still lacking.

MATERIALS AND METHODS

A computer search of electronic databases primarily MEDLINE and PUBMED was performed with the following key words: 'titanium hypersensitivity', 'titanium allergy', 'titanium release' without any language restriction. Manual searches of the bibliographies of all the retrieved articles were also performed. In addition, a complementary hand search was also conducted to identify recent articles and case reports.

RESULTS

Most of the literature comprised case reports and prospective in vivo/in vitro trials. One hundred and twenty-seven publications were selected for full text reading. The bulk of the literature originated from the orthopaedic discipline, reporting wear debris following knee/hip arthroplasties. The rest comprised osteosynthesis (plates/screws), oral implant/dental materials, dermatology/cardiac-pacemaker, pathology/cancer, biomaterials and general reports.

CONCLUSION

This review of the literature indicates that titanium can induce hypersensitivity in susceptible patients and could play a critical role in implant failure. Furthermore, this review supports the need for long-term clinical and radiographic follow-up of all implant patients who are sensitive to metals. At present, we know little about titanium hypersensitivity, but it cannot be excluded as a reason for implant failure.

Maxillofacial trauma--developments, innovations and controversies

Despite seat belt and alcohol legislation, craniofacial trauma still remains a common health problem and significant workload in many maxillofacial units. Although management has evolved considerably from "wiring teeth together", complex fractures can still result in cosmetic and functional deformity. Today's challenge is to consistently restore patients back to their pre-injury form and function-but this is not always possible. Greater understanding and developments have significantly improved outcomes, although controversy still exists in some areas. This review outlines some of these topics.

Titanium allergy in dental implant patients: a clinical study on 1500 consecutive patients

BACKGROUND

In dentistry, allergic reactions to Ti implants have not been studied, nor considered by professionals. Placing permanent metal dental implants in allergic patients can provoke type IV or I reactions. Several symptoms have been described, from skin rashes and implant failure, to non-specific immune suppression.

OBJECTIVE

Our objective was to evaluate the presence of titanium allergy by the anamnesis and examination of patients, together with the selective use of cutaneous and epicutaneous testing, in patients treated with or intending to receive dental implants of such material.

MATERIAL AND METHODS

Thirty-five subjects out of 1500 implant patients treated and/or examined (2002-2004) were selected for Ti allergy analysis. Sixteen presented allergic symptoms after implant placement or unexplained implant failures [allergy compatible response group (ACRG)], while 19 had a history of other allergies, or were heavily Ti exposed during implant surgeries or had explained implant failures [predisposing factors group (PFG)]. Thirty-five controls were randomly selected (CG) in the Allergy Centre. Cutaneous and epicutaneous tests were carried out.

RESULTS

Nine out of the 1500 patients displayed positive (+) reactions to Ti allergy tests (0.6%): eight in the ACRG (50%), one in the PFG (5.3%)(P=0.009) and zero in the control group. Five positives were unexplained implant failures (five out of eight).

CONCLUSIONS

Ti allergy can be detected in dental implant patients, even though its estimated prevalence is low (0.6%). A significantly higher risk of positive allergic reaction was found in patients showing post-op allergy compatible response (ACRG), in which cases allergy tests could be recommended.

Biodistribution of titanium dioxide from biologic compartments

The layer of titanium dioxide (TiO(2)) of the implant is chronically exposed to the internal electrolyte milieu in the peri-implant biological compartment. Corrosion results from electrochemical attack and ensuing gradual degradation of the metallic materials and is thus of biological interest when these biomaterials are employed in clinical implantology. Herein we evaluated and compared the chronic effect and the biodistribution of TiO(2) administered subcutaneously or intraperitoneally. We propose that the compartmentalization of titanium in the area of subcutaneous injection would reproduce the biological compartment of the implant and its microenvironment from which metal ions could be released and migrate systemically. Potential TiO(2) deposits were identified and characterized in skin, liver and lung by histological and EDX analyses. After both treatments, the skin, liver, and lungs exhibited histological evidence of TiO(2) deposits. In order to characterize in situ macrophage-like cells, tissue sections were immunohistochemically stained for CD68. Tissue specimens from all organs assayed showed positive staining for anti-macrophage monoclonal antibody CD68 (PGM1). Despite the compartmentalization of titanium within nodular areas in rats treated subcutaneously, systemic migration occurred. We concluded that systemic migration of TiO(2) occurred regardless of the administration route.

Correlation of histology of healed fractures and tissue surrounding implants with ultrasonographic and radiographic appearance

OBJECTIVES

To determine if there was histological correlation with ultrasonographic images of healed fractures and implant-associated tissue after fracture treatment by plate osteotomy.

METHODS

Eight adult dogs were included in this retrospective study. Ultrasonography (B-mode and power Doppler) and radiography were performed before plate removal. Surgical biopsies were taken of the fracture site and the tissue adjacent to the plate. These were stained with haematoxylin and eosin to assess histomorphology and bone content and immunolabelled with CD31 to assess vascularity.

RESULTS

Ultrasound and radiographic diagnoses of a healed fracture correlated with histological finding of bone healing. Ultrasonography and histology findings of vascularity were also highly correlated. The tissue surrounding the surgical implants was significantly more vascularised on both ultrasonography and histology than that at the fracture site itself.

CLINICAL RELEVANCE

Ultrasonography can be used to diagnose fracture healing in plated fractures. Power Doppler ultrasonography examination of fracture healing should be performed away from surgical implants to avoid false-positive results of vascularisation.

Ultrasonographic assessment of fracture healing after plate osteosynthesis

The goals of this study were to assess the ability of ultrasonography (US) to assess uncomplicated fracture healing and to establish normal images. Twenty-two dogs, ranging in age from 6 to 180 months were studied. Body weight ranged from 2.2 to 60 kg. All fractures were treated by plate osteosynthesis. US (B-mode and power Doppler) and radiography were performed until both were consistent with complete healing. B-mode US was performed in all dogs, and power Doppler US in 14. Fracture healing was judged to be complete based on US earlier than when based on radiography. The tissue immediately adjacent to the plate appeared vascularized on power Doppler images at a time when the tissue at the fracture site had a negative power Doppler exam. US appears useful for assessment of primary fracture healing and power Doppler was useful for detecting vascularization at the fracture site in nonhealed fractures. Power Doppler interrogation should be performed away from any metal implant, as a result from an interrogation adjacent to an implant will not reflect actual vascularization at the fracture site.