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).

Cell Phone Radiation Effect on Bone-to-Implant Osseointegration: A Preliminary Histologic Evaluation in Rabbits.

BACKGROUND AND PURPOSE: The increased use of cell phones has raised many questions as to whether their use is safe for patients with dental implants. This study aimed to assess the consequences of cell phone-emitted radiation on bone-to-implant osseointegration during the healing phase. MATERIALS AND METHODS: Twelve rabbits were grouped into three groups of four. Group 1 (control) was not exposed to electromagnetic radiation; group 2 (test) was exposed for 8 hours/day in speech mode and 16 hours/day in standby mode; and group 3 (test) was exposed for 24 hours continuously in standby mode for 3 months. Forty-eight implants were placed in tibia and femur bone of rabbits, and after 90 days the rabbits were sacrificed and bone surrounding the implant was retrieved. Histopathologic evaluations of the specimens were done using transmitted light microscope. The differences among the three groups were statistically analyzed with analysis of variance (ANOVA) and pairwise comparisons via Fisher's exact test. RESULTS: Significantly less bone-to-implant contact and bone area surrounding implant threads were found in the test groups compared to the control group. There was a significant difference in regular bone formation (P < .001) among the three groups. CONCLUSION: Implants exposed to cell phone radiation showed more inflammatory reaction when compared to the nonexposed implants, thus indicating that cellular phone overuse could affect the maturation of bone and thus delay osseointegration.

Inhibition of HMGB1 Promotes Osseointegration under Hyperglycemic Condition through Improvement of BMSC Dysfunction.

High mobility group box 1 (HMGB1) participates actively in oxidative stress damage and the latter relates closely to diabetic complications, including poor implant osseointegration. This article is aimed at investigating the effects of HMGB1 on dysfunction of bone marrow stromal cells (BMSCs) and impaired osseointegration under diabetic environment. In vitro, BMSCs were treated with normal glucose (NG), high glucose (HG), and HG+glycyrrhizin (HMGB1 inhibitor, HG+GL). Cell proliferation, osteogenic behaviors, and oxidative stress were determined. In vivo, 8-week-old Sprague-Dawley rats were categorized to control, streptozotocin-induced diabetic, and diabetic-GL groups. Rats received GL (50 mg/kg, i.p.) or vehicle treatment daily after titanium implants were planted into the tibiae. After 4 and 8 weeks, plasma lipoperoxide detection, µCT analysis, and histomorphometric evaluation were conducted. By these approaches, we demonstrated that inhibiting HMGB1 by GL significantly attenuated HG-induced upregulation of HMGB1, HMGB1 ligand receptor for advanced glycation end products (RAGE) and their interaction, relieved oxidative stress, and reversed the downregulation of osteogenic markers, resulting in improved osteogenic differentiation. In diabetic rats, GL administration suppressed the upregulation of HMGB1, attenuated the lipoperoxide, and ameliorated the impaired trabecular structure and osseointegration. Taken together, inhibiting HMGB1 can be an effective approach to relieve BMSC dysfunction and enhance osseointegration under diabetic environment.

Combination Use of BMP2 and VEGF165 Promotes Osseointegration and Stability of Titanium Implants in Irradiated Bone.

BACKGROUND: Clinical data demonstrated that failure rate of titanium implant in irradiated bone was 2-3 times higher than that in nonirradiated bone and it is difficult to get the ideal results in irradiated bone. PURPOSE: The aim of the study was to investigate the effects of HBO, BMP2, VEGF165, and combined use of BMP2/VEGF165 on osseointegration and stability of titanium implant in irradiated bone. MATERIALS AND METHODS: Sixty rabbits were randomly assigned to 5 groups (control group, HBO group, VEGF165 group, BMP2 group, and BMP2/VEGF165 group) after receiving 15 Gy radiation. Implant surgery was performed on tibias eight weeks later. They were sacrificed at two or eight weeks after operation. Implant stability, calcium, and ALP activity in serum, the ratio of bone volume to total volume, the rate of bone growth, and gene expression were assessed. RESULT: There was no mortality and no implants failed during the experiment. Implant stability was significantly compromised in the control group compared to the other four experimental groups, and the BMP2/VEGF165 group had the highest implant stability. HBO, BMP2, and VEGF165 significantly increased BV/TV and the rate of bone growth, while the BMP2/VEGF165 showed the best effect among groups. The expression of RUNX2 in HBO, BMP2, and VEGF165/BMP2 group was higher than that in the VEGF165 and control groups at two weeks. The expression of OCN in HBO, BMP2, VEGF165, and VEGF165/BMP2 groups was higher than that in the control group, and the gene expression of CD31 was higher in HBO, VEGF165, and BMP2/VEGF165 groups than that in control and BMP2 groups. CONCLUSION: HBO, BMP2, and VEGF165 could increase bone formation around the implant and improved the implant stability in irradiated bone. The combination use of BMP2 and VEGF165 may be promising in the treatment of implant patients with radiotherapy.

Dose-dependent effect of radiation on resorbable blast material titanium implants: an experimental study in rabbits.

BACKGROUND: Radiotherapy is a commonly used treatment modality in head and neck cancer; however, it also negatively affects healthy structures. Direct damage to oral soft and hard tissue frequently occurs with radiotherapy. In this study, we aimed to evaluate the effect of radiotherapy on bone surrounding titanium dental implants via biomechanical and molecular methods. MATERIALS AND METHODS: Fifty-four implants were inserted in the left tibiae of 18 adult male New Zealand rabbits (3 implants in each rabbit). After 4 weeks of the implant surgery, the left tibiae of 12 rabbits were subjected to a single dose of irradiation (15 Gy or 30 Gy). Four weeks after the irradiation, rabbits were sacrificed and removal torque test was done for the biomechanical evaluation. Bone morphogenetic protein-2 (Bmp-2) and fibroblast growth factor-2 (Fgf-2) expression analyses were performed with Real-time PCR. Statistical analysis was done using SPSS. RESULTS: The control group showed significantly higher removal torque value than the 15 and 30 Gy irradiation groups, and the 15 Gy irradiation group had higher removal torque value than the 30 Gy irradiation group (p < .001). The 15 Gy and 30 Gy irradiation groups had significantly lower Bmp-2 and Fgf-2 mRNA expressions than the control group (p < .001). In addition, the 30 Gy irradiation group had significantly lower Bmp-2 (p < .01) and Fgf-2 mRNA expressions (p < .001) than the 15 Gy group. CONCLUSION: Radiotherapy with 15 and 30 Gy doses can adversely affect osseointegration of implants by reducing the quality of bone and impairing the bone-to-implant contact. The mechanism of action seems to be related to alterations in Bmp-2 and Fgf-2 mRNA expressions.

Effects of low-level laser therapy and platelet concentrate on bone repair: Histological, histomorphometric, immunohistochemical, and radiographic study.

PURPOSE: Low-level laser therapy (LLLT) can increase bone metabolism, cell proliferation, and maturation, and reduce inflammation, while platelet concentrate (PC) assists bone healing process by releasing proteins and growth factors. Here, we evaluated the efficacy of combined LLLT and PC therapy in the healing of critical-size bone defects. MATERIALS AND METHODS: Calvarial critical-size defects 5 mm in diameter were made in 48 Wistar rats. Bones were removed, milled, and used as autogenous bone grafts. Animals were randomized into four groups: LP (LLLT + PC), PC, L (LLLT), and C (control, autogenous graft only). Animals were sacrificed at day 30 and 60 post-surgery. Specimens were submitted to radiographic (digital and conventional), histological, histomorphometric, and immunohistochemical analyses. RESULTS: Digital radiography was shown to be a better image analysis method compared with conventional radiography. Histological analysis demonstrated a significant difference in bone formation between animals in group L (p = 0.049) at day 60 than in other groups. Higher rates of inflammatory infiltrates and fibrosis were observed in the LP and PC groups at days 30 and 60, whereas the groups not receiving PC showed a higher rate of bone maturity. The inflammatory processes were reduced in the animals in the L group, together with new bone formation and maturation. Groups L and C had higher scores of positive osteocalcin immunostaining in bone and extracellular matrix. CONCLUSIONS: LLLT reduces inflammation and contributes to increased bone formation. PC treatment was shown to maintain connective tissue and to induce fibrosis during bone repair. Combined LLLT and PC treatment did not improve bone repair.

Effects of Ultraviolet Photofunctionalization on Bone Augmentation and Integration Capabilities of Titanium Mesh and Implants.

PURPOSE: Ultraviolet (UV)-mediated photofunctionalization has earned considerable attention for the enhancement of the biologic capabilities of titanium. The effects of photofunctionalization on bone augmentation and gap closure were examined using titanium implants and mesh in a rat femur model. MATERIALS AND METHODS: An acid-etched titanium implant (4-mm length, 1-mm diameter) was placed in the gluteal tuberosity that resembles a knife-edge-like edentulous ridge. The lower half of the implant was located in a 2-mm-diameter defect created in the bone without cortical bone support; the upper half was exposed and covered with a titanium mesh to provide augmentation space. After 12 and 24 days of healing, specimens were subjected to microcomputed tomography (micro-CT)- and histology-based bone morphometry in three zones of analysis: augmentation, cortical bone-implant gap, and bone marrow. A biomechanical push-in test was performed to examine the strength of bone-implant integration. Photofunctionalization was performed by treating titanium implants and mesh with UV light for 12 minutes. RESULTS: Photofunctionalized titanium mesh and implants were hydrophilic, whereas untreated controls were hydrophobic. Bone volume was significantly greater in photofunctionalized implants and mesh than in untreated implants in all zones on days 12 and 24. Bone-to-implant contact of photofunctionalized implants was greater than that of untreated implants, not just in the bone marrow but also in the gap and augmented zones. The strength of osseointegration was three times greater for photofunctionalized implants than for untreated implants. CONCLUSION: Use of photofunctionalized titanium mesh and implants effectively enhanced vertical bone augmentation, cortical bone-implant gap closure, and osseointegration without innate bone support.

Implant osseointegration in irradiated bone: an experimental study.

BACKGROUND AND OBJECTIVES: The aim of this study was to evaluate the effect of radiotherapy on the osseointegration of dental implants in the tibia and the action of platelet-rich plasma (PRP) as an adjuvant therapy. MATERIAL AND METHODS: A total of 18 rabbits received two implants in each tibial epiphysis, totalizing 72 implants. The control group (group I) was composed by six rabbits and did not receive radiotherapy. The test groups (II and III) received a single dose of 1727 cGy. Group II was composed by six irradiated animals and group III by six animals that received irradiation and PRP during implant placement. The implant success rate, the bone-implant contact (BIC), and the bone volume were analyzed. RESULTS: There was no osseointegration in four of the implants, three in group II and one in group III. Total BIC was significantly higher in group I, when compared to the other groups. There was a significant difference of osteoid BIC only between irradiated animals (group II, 8.5%; group III, 4.7%; p = 0.001). On the other hand, the mineralized BIC was significantly higher in group I. Furthermore, group II had a lower mineralized BIC than group III (p = 0.002). Bone volume was higher in the control group (41.3%), followed by group III (33.4%) and II (25.1%), with differences between groups I and II (p = 0.001) and groups II and III (p = 0.022). CONCLUSIONS: The present study showed that both the bone volume and BIC were higher in the control group. However, the failure rates of the implants were low in both irradiated groups. The PRP was a positive adjuvant in the osseointegration process.

Osseointegration and implant stability of extraoral implants in Göttingen minipigs after irradiation.

OBJECTIVES: The aim of this study was to compare the influence of implant surface treatment and irradiation dose on implant stability and osseointegration of 144 extraoral implants in irradiated frontal bone of minipigs. MATERIAL AND METHODS: 144 implants with 3 different surface treatments (machined, etched and HAVD-coated) were implanted in the frontal bone of 16 Göttingen minipigs. Three groups of four pigs received radiation with equivalent doses of 25, 50 and 70 Gy, and one group served as control. Resonance frequency analysis (RFA) was performed recording Implant Stability Quotients (ISQ) at implant placement and 3 months thereafter. Removal torque was measured whilst removing specific implants after 3 months. In addition, the bone-to-implant contact (BIC) was analyzed. RESULTS: Evaluation of ISQ, BIC-values showed no significant difference between the different surface treatments in irradiated and non-irradiated bone. Removal torque revealed statistically significant differences between machined and HAVD-coated implants in the irradiated bone. CONCLUSIONS: Implant stability and osseointegration, based on Removal Torque showed significant higher results for the HAVD-coated implants. No significant difference was observed between the irradiated and non-irradiated animals. This study shows that HAVD-coated extraoral implants can potentially be used for craniofacial rehabilitation in non-irradiated and irradiated bone.

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.

The In Vivo Bone Response of Ultraviolet-Irradiated Titanium Implants Modified with Spontaneously Formed Nanostructures: An Experimental Study in Rabbits.

PURPOSE: Acid etching in conjunction with storage in an aqueous solution can induce nanostructures forming spontaneously on titanium surfaces, but an inevitable biologic degradation is suspected to accompany the evolution of nanostructures. The aim of this study was to investigate whether ultraviolet (UV) irradiation is effective to solve this problem and further enhance the bioactivity. MATERIALS AND METHODS: Surface characteristics of five groups of titanium implants (SLAnew, SLAold, modSLA, UV-SLA, and UV-modSLA) and their in vivo bone response were analyzed in this study. The surface characteristics were evaluated with contact angle measurements, scanning electron microscopy, and x-ray photon spectroscopy. A total of 160 implants (32 for each group) were inserted into the tibial metaphyses and femoral condyles of 40 rabbits. After 3 and 6 weeks, the rabbits were euthanized for removal torque tests and histomorphometric analysis. RESULTS: Spontaneously formed nanostructures were observed on water-stored surfaces with a size of approximately 15 nm in diameter, and an inevitable contamination of hydrocarbons accompanied the evolution of nanostructures. UV irradiation effectively eliminated hydrocarbon contamination that accompanied nanostructure evolution. UV-modSLA implants showed the highest removal torque value, and UV-irradiated implants exhibited higher bone-to-implant contact and bone area. CONCLUSION: UV irradiation can effectively eliminate the hydrocarbon contamination accompanying the evolution of nanostructures and further enhance the osseointegration. Nanostructures and UV treatment have combined effects in enhancing the interfacial strength between titanium and bone, while UV photofunctionalization has much more overwhelming effects on histologic and histomorphometric performance.

Implant Stability Development of Photofunctionalized Implants Placed in Regular and Complex Cases: A Case-Control Study.

PURPOSE: The objective of this study was to compare the rate of implant stability development of as-received and photofunctionalized dental implants in regular and complex cases. MATERIALS AND METHODS: Forty-nine implants (24 as-received and 25 photofunctionalized) placed in regular or complex cases (simultaneous guided bone regeneration, sinus elevation, or fresh extraction sockets) were studied. Photofunctionalization was performed by ultraviolet (UV) treatment of implants for 15 minutes using a photo device immediately prior to placement, and the generation of superhydrophilicity was confirmed. Implant stability was evaluated by measuring the implant stability quotient (ISQ) at placement (ISQ1) and at stage-two surgery (ISQ2). The rate of implant stability development was evaluated by calculating the osseointegration speed index (OSI), defined as the ISQ increase per month ([ISQ2-ISQ1]/healing time in months). The percentage of innate bone support at placement was evaluated clinically and radiographically. RESULTS: The average OSI was considerably greater for photofunctionalized implants (3.7 ± 2.9) than for as-received implants (0.0 ± 1.0). The OSI in complex cases was 4.2 ± 3.2 for photofunctionalized implants and 0.2 ± 0.9 for as-received implants. The OSI in cases with simultaneous sinus elevation was 5.5 ± 3.5 for photofunctionalized implants and 0.2 ± 1.1 for as-received implants. Photofunctionalized implants showed significantly higher ISQ2 values than as-received implants. Photofunctionalized implant ISQ2 values were greater than 60, regardless of primary stability and innate bone support at placement. In multivariate analysis including the effects of photofunctionalization, age and sex of patients, and diameter and length of implants, photofunctionalization showed the strongest influence on the OSI for both regular and complex cases, while other factors influenced the OSI only in certain conditions. CONCLUSION: Photofunctionalization accelerated the rate and enhanced the final level of implant stability development compared with as-received implants, particularly for implants placed into poor-quality bone and other complex cases. Photofunctionalization was a stronger determinant of implant stability than all the other tested implant- and host-related factors.

CO2 laser surface treatment of failed dental implants for re-implantation: an animal study.

The aim of the present study was to evaluate the success rate of failed implants re-implanted after surface treatment with CO2 laser. Despite the widespread use of dental implants, there are many incidents of failures. It is believed that lasers can be applied to decontaminate the implant surface without damaging the implant. Ten dental implants that had failed for various reasons other than fracture or surface abrasion were subjected to CO2 laser surface treatment and randomly placed in the maxillae of dogs. Three failed implants were also placed as the negative controls after irrigation with saline solution without laser surface treatment. The stability of the implants was evaluated by the use of the Periotest values (PTVs) on the first day after surgery and at 1, 3, and 6 months post-operatively. The mean PTVs of treated implants increased at the first month interval, indicating a decrease in implant stability due to inflammation followed by healing of the tissue. At 3 and 6 months, the mean PTVs decreased compared to the 1-month interval (P < 0.05), indicating improved implant stability. The mean PTVs increased in the negative control group compared to baseline (P < 0.05). Independent t-test showed that the mean PTVs of treated implants were significantly lower than control group at 3 and 6 months after implant placement (P < 0.05). Based on the PTVs, re-implantation of failed implants in Jack Russell Terrier dogs after CO2 laser surface debridement is associated with a high success rate in terms of implant stability.

Effects of Low-Intensity Pulsed Ultrasound on Implant Osseointegration in Ovariectomized Rats.

OBJECTIVES: To investigate the effect of low-intensity pulsed ultrasound (US) on periimplant bone healing and osseointegration under osteoporotic conditions. METHODS: Seventy-two 12-week-old female Sprague Dawley rats received bilateral ovariectomies. Twelve weeks later, titanium implants were bilaterally placed in the proximal tibial metaphysis. The right tibia was exposed to low-intensity pulsed US (40 mW/cm2, spatial and temporal average) for 20 min/d starting the 2nd day after implantation, and the left tibia served as a control without stimulation. The rats were randomly assigned to 6 groups of 12 each according to the US duration (group 1: weeks 0­2, 280 minutes; group 2: weeks 0­4, 560 minutes; group 3: weeks 0­6, 840 minutes; group 4: weeks 0­8, 1120 minutes; group 5: weeks 0­10, 1400 minutes; group 6: weeks 0­12, 1680 minutes). At the end of the 2nd, 4th, 6th, 8th, 10th, and 12th weeks, the rats were euthanized, and bilateral tibias were harvested. Peri-implant bone volume and bone-implant contact were assessed by micro­computed tomography; the implantbone interface was assessed histologically; and implant fixation strength was determined by a removal torque test. RESULTS: Low-intensity pulsed US increased bone-implant contact at the 4th, 6th, 8th, 10th, and 12th weeks (P = .019, .017, <.001, <.001, and <.001, respectively) and periimplant bone volume at all times (P = <.001, .002, .012, .007, .005, and .010). Removal torque on the US side was improved at the 6th, 8th, 10th, and 12th weeks (P= .012, <.001, .006, and .009). Ultrasound evoked a favorable bone response in the histologic study. CONCLUSIONS: Low-intensity pulsed US might enhance new bone formation, especially at an early stage, and improve osseointegration in osteoporotic bone as an auxiliary method. However, further studies are needed to elucidate the mechanisms underlying its action.

A influência do laser de baixa intensidade na osseointegração de implantes de titânio ­ revisão sistemática / The influence of low-level laser therapy (LLLT) on the osseointegration of titanium implants ­ a systematic review

Objetivo: fazer uma revisão da literatura sobre o laser de baixa intensidade (LLLT) e seus efeitos na osseointegração dos implantes de titânio. Material e métodos: uma busca eletrônica foi realizada nos bancos de dados PubMed/Medline e Cochrane Library, entre 1995 e 2015, limitando-se aos artigos em inglês e usando as seguintes palavras-chave: "LLLT", "dental implant" e "osseointegration", combinadas por operadores booleanos. Resultados: das 96 referências analisadas inicialmente, apenas 17 artigos foram incluídos (15 estudos em animais, dois estudos em humanos). Quinze artigos mostraram efeitos positivos da LLLT, enquanto dois foram neutros. Houve grande variabilidade no uso da LLLT, sobretudo no que se refere à dose utilizada, ao número de sessões, à energia de irradiação, e ao comprimento de onda. Conclusão: mais pesquisas sobre este tema são necessárias, utilizando doses padronizadas, assim como comprimento de onda e protocolos de aplicação pré-definidos.

Objective: to perform a systematic review on low-level laser therapy (LLLT) and its effects on the osseointegration of titanium implants. Material and methods: an electronic search was on the PubMed/Medline database and Cochrane Library between 1995 e 2015, restricted to the English literature and using the keywords: "LLLT", "dental implant", and "osseointegration" combined by Boolean operators. Results: from the 96 initially retrieved references, only 17 articles were included (15 animal studies, 2 human studies). Fifteen articles showed positive effects, while only two demonstrated neutral effects of LLLT. A great variability was found on LLLT regarding doses, number of sessions, energy, and wavelengths used. Conclusion: further research on this topic need to be made using standard doses, wavelengths, and pre-defi ned application protocols.

Outcomes and complications of osseointegrated hearing aids in irradiated temporal bones.

OBJECTIVES/HYPOTHESIS: To compare the complication rate for osseointegrated hearing aids (OIHA) in patients with or without irradiation. STUDY DESIGN: Retrospective case review. METHODS: We studied patients with OIHAs implanted between January 1, 2005, and July 15, 2013 in a tertiary university center with a referral otology and neurotology practice. Demographics, history of oncologic surgery, follow-up length after OIHA implantation, radiation history and dosage, postoperative complications, and chronologic relationship between oncologic resection, OIHA implantation, and irradiation were reviewed to collect information. Soft tissue complications were graded according to a modified Holgers classification. RESULTS: The study included 48 patients. Twenty-nine patients (32 implants) did not undergo radiotherapy and 19 patients (19 implants) did. In the radiotherapy group, six patients had OIHAs implanted before radiotherapy, and 13 had OIHAs implanted in irradiated bone. Of these 13 patients, one had OIHA implanted during primary oncologic surgery; 11 had OIHA implanted during secondary surgery; and one patient did not have oncologic surgery. Patients with both OIHA implantation and radiotherapy had more complications than patients without radiotherapy (31.6% vs. 24.1%, P > 0.05) and more major complications than patients without radiotherapy (26.3% vs. 3.4%, P > 0.05). Patients with OIHAs implanted before radiotherapy did not have any complications. There were significantly fewer and less severe complications in patients with OIHAs implanted during primary oncologic resection than in patients with OIHAs implanted secondarily (0/8 vs. 8/11, P < 0.05). CONCLUSIONS: The rate and severity of complications of OIHAs can be minimized by implanting the device before irradiation, ideally at the time of primary oncologic surgery. LEVEL OF EVIDENCE: 4. Laryngoscope, 126:1187-1192, 2016.

Tissue response after implantation of pure titanium and bioresorbable screws in scapula with postoperative irradiation: an experimental study on rats.

OBJECTIVE: The study focuses on the comparison of tissue reaction to titanium and bioresorbable implants with and without postoperative irradiation on an animal model. MATERIALS AND METHODS: Thirty-nine LEW/W rats were randomly assigned to experimental or control groups. One titanium and one bioresorbable screw (poly-L-lactide [PLLA] and L- and D-lactide poly-L/D-lactide [PDLLA]) were implanted into the left scapulas of 24 rats. Half of them received 30 Gy to the operation site and the other half received 42 Gy. In the control groups, 3 rats received 30 Gy, and 6 rats received 42 Gy to the scapula area without operation; and 6 rats had implants inserted as in the experimental group, but received no postoperative irradiation. The scapulas were removed 14 or 30 days after irradiation and a histologic analysis was performed. RESULTS: The host tissue reaction to titanium and PLLA-PDLLA screws without postoperative irradiation was of similar intensity. In irradiated animals, the inflammatory tissue reaction was more evident around the titanium screws than around the bioresorbable screws, irrespective of the radiation dose and of the time that elapsed from the irradiation. The reaction was more evident on the 14th day than on the 30th day after the last radiation dose (70 and 86 days after surgery, respectively). The intensity of the inflammatory tissue reaction, irrespective of the implant type, was more intense in the group irradiated with 42 Gy. CONCLUSIONS: PLLA-PDLLA implants appear to cause less tissue reaction after irradiation and could be safer reconstructive devices than titanium implants for patients undergoing surgery and adjuvant radiotherapy for cancer.

Effects of calcium phosphate nanocrystals on osseointegration of titanium implant in irradiated bone.

Radiotherapy may compromise the integration of implant and cause implant loss. Implant surface modifications have the possibility of promoting cell attachment, cell growth, and bone formation which ultimately enhance the osseointegration process. The present study aimed to investigate the effects of calcium phosphate nanocrystals on implant osseointegration in irradiated bone. Sixteen rabbits were randomly assigned into control and nano-CaP groups, receiving implants with dual acid-etched surface or dual acid-etched surface discretely deposited of nanoscale calcium-phosphate crystals, respectively. The left leg of all the rabbits received 15 Gy radiation, followed by implants placement one week after. Four animals in each group were sacrificed after 4 and 12 weeks, respectively. Implant stability quotient (ISQ), ratio of bone volume to total volume (BV/TV), bone growth rate, and bone-to-implant contact (BIC) were evaluated. The nano-CaP group showed significantly higher ISQ (week 12, P = 0.031) and bone growth rate (week 6, P = 0.021; week 9, P = 0.001) than that in control group. No significant differences in BV/TV and BIC were found between two groups. Titanium implant surface modified with CaP nanocrystals provides a potential alternative to improve bone healing around implant in irradiated bone.

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.

Assessment of implant stability of patients with and without radiotherapy using resonance frequency analysis.

The purpose of this study was to clinically monitor the stability of dental implants in patients with and without a history of radiotherapy, using resonance frequency analysis over 1 year. The stability of patients with 80 implants was monitored with resonance frequency analysis (Osstell Mentor) over 1 year. Data were assessed with Mann-Whitney U test and correlation analysis. Irradiated maxillary implants showed statistically lower values than the mandibular implants at a significant level (P < .05).