The effect of ultraviolet photofunctionalization of titanium instrumentation in lumbar fusion: a non-randomized controlled trial.

BACKGROUND: Titanium instrumentations are widely used in orthopedics; the metal bonds with bone in a process called osseointegration. Over time, hydrocarbons adhere to the instrumentation, which weakens the bone-binding ability. Ultraviolet photofunctionalization enhances the bone-binding ability of instrumentation by reducing hydrocarbons. The process has been proven effective in dentistry, but its effects in orthopedics are unverified. We aimed to determine the effect of ultraviolet photofunctionalization of titanium instrumentation used in lumbar fusion. METHODS: This was a non-randomized controlled trial. We prospectively enrolled 13 patients who underwent lumbar fusion surgery. We inserted two pure titanium cages into each intervertebral space; one cage had undergone ultraviolet photofunctionalization, while the other was untreated. The degree of osteosclerosis around both cages was then compared by measuring the densities around the cages on imaging at 2, 3, 6, and 12 months postoperatively compared with 1 month postoperatively. The carbon attachment of the titanium cages was measured using X-ray photoelectron spectroscopy. RESULTS: There was no significant difference between the degree of osteosclerosis (as assessed by the density) around the treated versus untreated cages at any timepoint. The ratio of carbon attachment of the titanium cages was only 20%, which was markedly less than the ratio of carbon attachment to titanium instrumentation previously reported in the dentistry field. CONCLUSIONS: The effect of ultraviolet photofunctionalization of titanium instrumentation in spine surgery is questionable at present. The biological aging of the titanium may be affected by differences in the manufacturing process of orthopedics instrumentation versus dentistry instrumentation. TRIAL REGISTRATION: UMIN Clinical Trials Registry (Identifier: UMIN000014103 ; retrospectively registered on June 1, 2014).

The effect of alendronate soaking and ultraviolet treatment on bone-implant interface.

OBJECTIVE: Rapid and stable fixation of dental implants is crucial for successful treatment. Herein, we examined whether the simultaneous treatment of titanium implants with ultraviolet (UV) and alendronate (ALN) synergistically improved the bone-to-implant contact. MATERIALS AND METHODS: We assessed the in vitro effects of UV radiation-treated (UV+/ALN-), ALN-soaked (UV-/ALN+), and UV radiation/ALN-treated (UV+/ALN+) titanium implants on cell proliferation, cytotoxicity, cell adhesion, and osteoblast differentiation using MG-63 osteoblast-like cells by the assays of MTS, live/dead, scanning electron microscopy (SEM), alkaline phosphatase (ALP) activity, and alizarin red S (AR-S) staining, respectively. Furthermore, in vivo bone formation at the bone-implant interface efficiency determined using a rabbit tibia implantation. Implants were divided into 3 experimental groups (UV+/ALN-, UV-/ALN+, UV+/ALN+) and the non-treated control (UV-/ALN-) group and transplanted into the proximal tibia of rabbits. At 1, 2, 4, and 8 weeks post-operation, bone formation at the bone-implant interface was evaluated by micro-computed tomography and histological analysis. RESULTS: MG-63 cells cultured on UV+/ALN+ implants showed significantly higher cell proliferation, ALP activity, and calcium mineralization than those cultured on other implants (P < 0.05). Furthermore, SEM observation showed the highest increase in cell attachment and growth on the UV+/ALN+ implants. In vivo, experimental groups at all time points showed greater peri-implant bone formation than the control group. At 8 weeks post-implantation, in the UV+/ALN+ group, significantly higher bone formation was observed than the UV+/ALN- or UV-/ALN+ group, respectively (P < 0.05). CONCLUSIONS: Treatment of titanium surfaces with UV and ALN may synergistically enhance osteoblastic differentiation and mineralization in vitro and enhance bone formation at the bone-implant interface in vivo. These data suggest that UV and ALN treatment may improve the osseointegration of titanium implants.

Effect of UV Photofunctionalization on Osseointegration in Aged Rats.

OBJECTIVES: This study evaluated the effect of photofunctionalization on osseointegration under the biologically adverse conditions of aging. MATERIALS: First of all, bone marrow-derived osteoblastic cells from young (8 weeks old) and aged (15 months old) rats were biologically characterized. Then, the osteoblasts from aged rats were seeded on titanium discs with and without photofunctionalization, and assessed for initial cell attachment and osteoblastic functions. Titanium mini-implants, with and without photofunctionalization, were placed in the femur of aged rats, and the strength of osseointegration was measured at week 2 of healing. Periimplant tissue was examined morphologically and chemically using scanning electron microscopy and energy dispersive x-ray spectroscopy, respectively. RESULTS: Cells from the aged rats showed substantially reduced biological capabilities compared with those derived from young rats. The cells from aged rats showed significantly increased cell attachment and the expression of osteoblastic function on photofunctionalized titanium than on untreated titanium. In addition, the strength of osseointegration was increased by 40% in aged rats carrying the photofunctionalized implants. Robust bone formation was observed around the photofunctionalized implants with strong elemental peaks of calcium and phosphorus, whereas the tissue around untreated implants showed weaker calcium and phosphate signals than titanium ones. CONCLUSION: These in vivo and in vitro results corroboratively demonstrate that photofunctionalization is effective for enhancing osseointegration in aged rats.

UV Photofunctionalization Effect on Bone Graft in Critical One-Wall Defect around Implant: A Pilot Study in Beagle Dogs.

The purpose of this study was to compare and evaluate, through histomorphometric and radiological analysis, the effects of UV photofunctionalization on an implant placed over a critical defect area with and without a bone graft. Four female beagle dogs were first divided into control and bone graft groups. Each group was then subdivided into UV-treated and UV-untreated groups. The mandibular premolars in each dog were extracted. 12 weeks after extraction, implants were placed according to the condition of each group. Four and 12 weeks after implantation on left and right mandible, the dogs were sacrificed. The specimens were prepared for histomorphometric and micro-computed tomographic analysis. In both 4-week and 12-week groups, UV-treated implant surfaces showed better osseointegration than SA implant surfaces. Also, with implant surfaces placed over the critical defect with bone graft, UV photofunctionalization increased bone-to-implant contact (BIC) and new bone formation at the initial stage (4 weeks). Based on the results of this study, it can be suggested that UV photofunctionalization on the surface of implants placed over large critical defects with bone graft aids initial osseointegration and osteogenesis.

Engineering bone-implant integration with photofunctionalized titanium microfibers.

There are significant challenges in regenerating large volumes of bone tissue, and titanium implant therapy is extremely difficult or contraindicated when there is no supporting bone. Surface conditioning of titanium implants with UV light immediately prior to use, or photofunctionalization, improves the speed and degree of bone-implant integration. Here, we hypothesized that photofunctionalized titanium microfibers are capable of promoting bone ingrowth into the microfiber scaffold to improve bone-implant integration in bone defects. Titanium implants (1 mm in diameter, 2 mm in length) enfolded with 0.7 mm-thick titanium microfibers were placed into 2.4-mm diameter osteotomy in rat femurs. Titanium microfibers and implants were photofunctionalized by treatment with UV light for 12 min using a photo device immediately prior to surgery. Photofunctionalized microfibers and implants were hydrophilic, while as-made microfiber-enfolded implants were hydrophobic. Implant anchorage strength was 2.5 times and 2.2 times greater for photofunctionalized microfiber-enfolded implants than as-made ones at weeks 2 and 4 of healing, respectively. Robust bone formation was only seen at the implant surface of photofunctionalized microfiber-enfolded implants. Bone formation as measured by the Ca/Ti ratio was 5 to over 20 times greater for photofunctionalized than as-made microfiber scaffolds. The Ca/P ratio was 1.55-1.65 in the tissue produced in photofunctionalized microfibers and 1.1-1.3 in tissue in as-made microfibers. In vitro, the number of attached osteoblasts and their alkaline phosphatase activity, both near zero on as-received microfibers, were significantly increased on photofunctionalized microfibers. In conclusion, bone ingrowth occurred in photofunctionalized titanium microfiber scaffolds, enabling successful bone-implant integration when the microfiber-enfolded implants were placed in a site without primary bone support. The combined use of titanium microfibers and photofunctionalization may provide a novel and effective strategy to regenerate and integrate bone in a wider range of applications.

Effect of Photofunctionalization on Ti6Al4V Screw Stability Placed in Segmental Bone Defects in Rat Femurs.

PURPOSE: Ultraviolet-mediated photofunctionalization is a new technology to improve bone and titanium integration. We hypothesized that photofunctionalization would enhance the stability of titanium screws used for segmental bone defects. MATERIALS AND METHODS: Disks were prepared of a titanium alloy (Ti6Al4V) for an in vitro study to evaluate the attachment, proliferation, and differentiation of osteoblasts. Commercially available Ti6Al4V screws were used in vivo. Segmental bone defects were created in rat femurs as an immediate loading reconstruction model. The defects were reconstructed with commercially available titanium plates and Ti6Al4V screws, with or without photofunctionalization. The screw survival rates and mechanical stability were evaluated at 2 and 4 weeks, and the bone formation around the screws was analyzed. RESULTS: Osteoblasts showed greater attachment, proliferation, and differentiation on the photofunctionalized Ti6Al4V disks. Photofunctionalized screws had significantly greater survival rates and mechanical stability at 2 and 4 weeks. The bone formation around the photofunctionalized screws was significantly greater than that around the untreated screws at 4 weeks. CONCLUSIONS: The results of the present study have demonstrated the efficacy of photofunctionalization on enhancing the survival and stability of Ti6Al4V screws under a loaded condition in the reconstruction of segmental defects. This was associated with increased bioactivity and bone formation around the photofunctionalized Ti6Al4V material.

Histologic and Resonance Frequency Analysis of Peri-Implant Bone Healing After Low-Level Laser Therapy: An In Vivo Study.

PURPOSE: To evaluate the effects of low-level laser therapy (LLLT) on peri-implant bone regeneration by means of resonance frequency analysis and histologic analysis of bone-to-implant contact (BIC). MATERIALS AND METHODS: Thirty-two male New Zealand rabbits were randomly divided into four groups of eight animals each, one control group (nonirradiated animals) and three experimental groups that received LLLT (group E5 = 5 J per session; group E10 = 10 J per session; group E20 = 20 J per session). The mandibular left incisor was surgically extracted in all animals, and a nanoparticle-treated-surface osseointegrated implant was placed immediately afterward. The experimental groups were irradiated with aluminum-gallium-arsenide laser diode every 48 hours over a 13-day period for a total of seven sessions. Implant stability quotients (ISQs) were measured at the time of implant placement and 30 days after the last LLLT session. The animals were then euthanized and dissected, and histologic slides of the implant region were obtained for BIC evaluation. RESULTS: Significant differences in ISQ were detected between groups before and after LLLT, with group E20 showing significantly higher values than controls. The percentage of BIC was also significantly higher in group E20 than in control animals. CONCLUSION: Laser therapy at a dose of 20 J per treatment session, based on the irradiation protocol used in this study, was able to significantly increase ISQ values and BIC after implant placement, indicating that laser irradiation effected an improvement in peri-implant bone healing.

3D silicone rubber interfaces for individually tailored implants.

For the fabrication of customized silicone rubber based implants, e.g. cochlear implants or electrocortical grid arrays, it is required to develop high speed curing systems, which vulcanize the silicone rubber before it runs due to a heating related viscosity drop. Therefore, we present an infrared radiation based cross-linking approach for the 3D-printing of silicone rubber bulk and carbon nanotube based silicone rubber electrode materials. Composite materials were cured in less than 120 s and material interfaces were evaluated with scanning electron microscopy. Furthermore, curing related changes in the mechanical and cell-biological behaviour were investigated with tensile and WST-1 cell biocompatibility tests. The infrared absorption properties of the silicone rubber materials were analysed with fourier transform infrared spectroscopy in transmission and attenuated total reflection mode. The heat flux was calculated by using the FTIR data, emissivity data from the infrared source manufacturer and the geometrical view factor of the system.

Stability and survival of bone-anchored hearing aid implant systems in post-irradiated patients.

Bone-anchored hearing aids (BAHAs) are based on the principle of osseointegration, which is fundamental to implant stability and survival. Previous exposure to ionising radiation may compromise this, as evidenced in relation to dental and craniofacial implants. There is a dearth of data, however, regarding BAHA implant systems in patients with previously irradiated implant sites. We sought, therefore, to investigate implant stability and survival in such patients. Patients were identified retrospectively from our electronic BAHA database. Hospital records were reviewed for demographics; operative technique; complications; and details regarding previous irradiation. Implant stability was assessed by resonance frequency analysis (RFA), generating a numerical value-implant stability quotient (ISQ). Extrapolating from dental studies, successfully loaded implants typically have ISQs of ≥60. Readings were, therefore, interpreted with respect to this. Seven patients were identified for inclusion. Mean time between irradiation and implant insertion was 33 months (range 16-72 months), and mean time from implant insertion to RFA measurement was 41 months (range 3-96 months). Operatively, all patients underwent single-stage procedures under local anaesthesia. One patient suffered a Holger's grade 2 skin reaction, while two suffered significant skin flap failure, requiring revision procedures. The implant survival rate was 100 %. All ISQ values were >60, with a mean of 66.9 (95 % confidence interval 63.1-70.6). Our data support sufficient osseointegration of BAHA implant systems in post-irradiated patients, but highlight issues with wound healing. Contemporary soft tissue preservation operative techniques will likely overcome this, facilitating safe and efficacious BAHA insertion in this ever-increasing group of patients.