Assessment of bone ingrowth around beaded coated tibial implant for total ankle replacement using mechanoregulatory algorithm.

The long-term performance of porous coated tibial implants for total ankle replacement (TAR) primarily depends on the extent of bone ingrowth at the bone-implant interface. Although attempts were made for primary fixation for immediate post-operative stability, no investigation was conducted on secondary fixation. The aim of this study is to assess bone ingrowth around the porous beaded coated tibial implant for TAR using a mechanoregulatory algorithm. A realistic macroscale finite element (FE) model of the implanted tibia was developed based on computer tomography (CT) data to assess implant-bone micromotions and coupled with microscale FE models of the implant-bone interface to predict bone ingrowth around tibial implant for TAR. The macroscale FE model was subjected to three near physiological loading conditions to evaluate the site-specific implant-bone micromotion, which were then incorporated into the corresponding microscale model to mimic the near physiological loading conditions. Results of the study demonstrated that the implant experienced tangential micromotion ranged from 0 to 71 µm with a mean of 3.871 µm. Tissue differentiation results revealed that bone ingrowth across the implant ranged from 44 to 96 %, with a mean of around 70 %. The average Young's modulus of the inter-bead tissue layer varied from 1444 to 4180 MPa around the different regions of the implant. The analysis postulates that when peak micromotion touches 30 µm around different regions of the implant, it leads to pronounced fibrous tissues on the implant surface. The highest amount of bone ingrowth was observed in the central regions, and poor bone ingrowth was seen in the anterior parts of the implant, which indicate improper osseointegration around this region. This macro-micro mechanical FE framework can be extended to improve the implant design to enhance the bone ingrowth and in future to develop porous lattice-structured implants to predict and enhance osseointegration around the implant.

Improved visualization of the bone-implant interface and osseointegration in ex vivo acetabular cup implants using photon-counting detector CT.

BACKGROUND: Successful osseointegration of joint replacement implants is required for long-term implant survival. Accurate assessment of osseointegration could enable clinical discrimination of failed implants from other sources of pain avoiding unnecessary surgeries. Photon-counting detector computed tomography (PCD-CT) provides improvements in image resolution compared to conventional energy-integrating detector CT (EID-CT), possibly allowing better visualization of bone-implant-interfaces and osseointegration. The aim of this study was to assess the quality of visualization of bone-implant-interfaces and osseointegration in acetabular cup implants, using PCD-CT compared with EID-CT. METHODS: Two acetabular implants (one cemented, one uncemented) retrieved during revision surgery were scanned using PCD-CT and EID-CT at equal radiation dose. Images were reconstructed using different reconstruction kernels and iterative strengths. Delineation of the bone-implant and bone-cement-interface as an indicator of osseointegration was scored subjectively for image quality by four radiologists on a Likert scale and assessed quantitatively. RESULTS: Delineation of bone-implant and bone-cement-interfaces was better with PCD-CT compared with EID-CT (p ≤ 0.030). The highest ratings were given for PCD-CT at sharper kernels for the cemented cup (PCD-CT, median 5, interquartile range 4.25-5.00 versus EID-CT, 3, 2.00-3.75, p < 0.001) and the uncemented cup (5, 4.00-5.00 versus 2, 2-2, respectively, p < 0.001). The bone-implant-interface was 35-42% sharper and the bone-cement-interface was 28-43% sharper with PCD-CT compared with EID-CT, depending on the reconstruction kernel. CONCLUSIONS: PCD-CT might enable a more accurate assessment of osseointegration of orthopedic joint replacement implants. KEY POINTS: • The bone-implant interface ex vivo showed superior visualization using photon-counting detector computed tomography (PCD-CT) compared to energy-integrating detector computed tomography. • Harder reconstruction kernels in PCD-CT provide sharper images with lower noise levels. • These improvements in imaging might make it possible to visualize osseointegration in vivo.

Comparison of three-dimensional digital analyses and two-dimensional histomorphometric analyses of the bone-implant interface.

Histological analysis is considered to be the gold standard method of evaluating osseointegration around a bone-implant. However, this method requires invasive specimen preparation and is capable of representing only one plane. By comparison, micro-computed tomography (µCT) is a fast and convenient method that offers three-dimensional information but is hampered by problems related to resolution and artifacts, making it a supplementary method for osseointegration analysis. To verify the reliability of µCT for osseointegration evaluation, this animal model study compared bone-to-implant contact (BIC) ratios obtained by the gold standard histomorphometric method with those obtained by the µCT method, using a rabbit tibia implant model. A sandblasted, large-grit, acid-etched (SLA) implant and a machined surface implant were inserted into each tibia of two rabbits (giving eight implants in total). Bone-implant specimens were analyzed using µCT with a spiral scan technique (SkyScan 1275) and histological sections were prepared thereafter. Three-dimensional (3D) reconstructed µCT data and four two-dimensional (2D) µCT sections, including one section corresponding to the histologic section and three additional sections rotated 45°, 90°, and 135°, were used to calculate the BIC ratio. The Pearson's test was used for correlation analysis at a significance level of 0.05. The histomorphometric BIC and the 2D-µCT BIC showed strong correlation (r = 0.762, P = 0.046), whereas the histomorphometric BIC and 3D-µCT BIC did not (r = -0.375, P = 0.385). However, the mean BIC value of three or four 2D-µCT sections showed a strong correlation with the 3D-µCT BIC (three sections: r = 0.781, P = 0.038; four sections: r = 0.804, P = 0.029). The results of this animal model study indicate that µCT can be used to complement the histomorphometric method in bone-implant interface analyses. With the limitations of this study, 3D-µCT analysis may even have a superior aspect in that it eliminates random variables that arise as a consequence of the selected cutting direction.

Early Bone Healing on Hydroxyapatite-Coated and Chemically-Modified Hydrophilic Implant Surfaces in an Ovine Model.

Implant topography affects early peri-implant bone healing by changing the osteoconduction rate in the surrounding biological environment. Implant surfaces have been designed to promote faster and stronger bone formation for rapid and stable prosthesis loading. Early peri-implant bone healing has been observed with a sandblasted, acid-etched implant that was chemically modified to be hydrophilic (cmSLA). The present study investigates whether early peri-implant bone healing extends to a rough surface implant with a high crystalline hydroxyapatite surface (TSV MP-1 HA). Three implants were randomly placed in porous trabecular bone within both medial femoral condyles of 10 sheep. Early peri-implant bone stability was measured at 3- and 6-weeks healing time following implant insertion. Results indicated a similar implant stability quotient between the implants at insertion and over time. The significant increase over time of reverse torque values with respect to insertion torque (p < 0.001) did not differ between the implants. However, the bone-to-implant contact of TSV MP-1 HA was significantly higher than that of cmSLA implants at 6 weeks (p < 0.01). These data validate previous findings of a hydrophilic implant surface and extend the observation of early osseointegration to a rough surface implant in porous trabecular bone.

Development and first biomechanical validation of a score to predict bone implant interface stability based on clinical qCT scans.

Sufficient implant anchoring in osteoporotic bone is one major challenge in trauma and orthopedic surgery. In these cases, preoperative planning of osteosynthesis is becoming increasingly important. This study presents the development and first biomechanical validation of a bone-implant-anchorage score based on clinical routine quantitative computer tomography (qCT) scans. 10 pairs of fresh frozen femora (mean age 77.4 years) underwent clinical qCT scans after placing 3 referential screws (for matching with the second scan). Afterwards, three 4.5 mm cortical screws (DePuy Synthes, Zuchwil, Switzerland) were placed in each distal femur in the dia-metaphyseal transition followed by the second CT scan. The femur was segmented using thresholding and its outer shape was visualized as a surface model. A 3D model of the cortex screw in STL format was used to model the screw surface precisely. For each femur, the 3 cortex screw models were exactly positioned at the locations previously determined using the second CT scan. The BMD value was calculated at the center of each triangle as an interpolation from the measured values at the three vertices (triangle corners) in the CT. Scores are based on the sum of all the triangles' areas multiplied by their BMD values. Four different scores were calculated. A screw pull-out test was performed until loss of resistance. A quadratic model adequately describes the relation between all the scores and pull-out values. The square of the best score explains just fewer than 70% of the total variance of the pull-out values and the standardized residual which were approximately normally distributed. In addition, there was a significant correlation between this score and the peak pull-out force (p < 0.001). The coefficient of determination was 0.82. The presented score has the potential to improve preoperative planning by adding the mechanical to the anatomical dimension when planning screw placement.

Homogenous Bone Grafts as an Alternative in Oral Rehabilitation Treatments with Dental Implants / Los Injertos Óseos Homogéneos como una Alternativa en los Tratamientos de Rehabilitación Oral con Implantes Dentales

ABSTRACT: The present study aims to describe, through a case report, the functioning of bone grafts, where they are obtained including bone banks and the different dental areas in which it is used. A 50-year.old female patient HMR, sought the postgraduate college of dentistry CECAPE for oral rehabilitation. The initial clinical examination revealed the absence of several dental elements in both the maxilla and mandi ble, bone resorption in the entire maxillary extension where there was an absence of elements in the anterior region and the presence of a torus in the palatal region. Initial tomographic examinations of the maxilla and mandible were performed, looking for the best conduct regarding the diagnosis and planning of the case. After the clinical and radiographic examinations was performed, and the diagnosis was reached, it was determined as a treatment for oral rehabilitation of the maxilla, bone grafting and an Implant-supported Removable Partial Prosthesis and for the mandible a Dento-muco-supported Removable Partial Prosthesis. Dental treatments and oral rehabilitation from the use of bone tissues and bone grafting have become commonly used. Procedures that would normally lead to failure started to increase the percentage of successes due to the use of these biomaterials. The use of bone grafts in dentistry has been shown to be a very effective and useful resource, considering its great applicability in bone reconstructions in different areas of dentistry.

RESUMEN: El presente estudio tiene como objetivo describir a través de un informe de caso, el funcionamiento de los injertos óseos, donde se obtienen, incluidos los bancos de huesos y las diferentes áreas dentales en las que se emplea. Una paciente HMR, de 50 años de edad, asistió el centro universitario de posgrado CECAPE para rehabilitación oral. El examen clínico inicial reveló la ausencia de varios dientes tanto en el maxilar como en la mandíbula, la resorción ósea en toda la extensión maxilar donde había ausencia de dientes en la región anterior y la presencia de un torus en la región palatina. Se realizaron exámenes tomográficos iniciales del maxilar y mandíbula, buscando la mejor conducta con respecto al diagnóstico y la planificación del caso. Después de los exámenes clínicos y radiográficos realizados y el diagnóstico listo, se determinó como un tratamiento para la rehabilitación oral del maxilar, el injerto óseo y una prótesis removible implantosoportada y para la mandíbula una prótesis parcial removible dento-muco-soportada. Los tratamientos dentales y la rehabilitación oral a partir del uso de tejidos óseos y el injerto óseo se han utilizado comúnmente. Los procedimientos que normalmente conducirían al fracaso comenzaron a aumentar el porcentaje de éxitos debido al uso de estos biomateriales. Se ha demostrado que el uso de injertos óseos en odontología es un recurso muy eficaz y útil, considerando su gran aplicabilidad en las reconstrucciones óseas en diferentes áreas de la odontología.

Postoperative Administration of the Acetylcholinesterase Inhibitor, Donepezil, Interferes with Bone Healing and Implant Osseointegration in a Rat Model.

Donepezil is an acetylcholinesterase inhibitor commonly used to treat mild to moderate Alzheimer's disease. Its use has been associated with increased bone mass in humans and animals. However, the effect of postoperative administration of donepezil on bone healing remains unknown. Therefore, this study aimed to assess the impact of postoperative injection of donepezil on bone healing, titanium-implant osseointegration, and soft tissue healing. Twenty-two Sprague-Dawley rats were randomly assigned to receive a daily dose of either donepezil (0.6 mg/kg) or saline as a control. In each rat, a uni-cortical defect was created in the right tibia metaphysis and a custom-made titanium implant was placed in the left tibiae. After two weeks, rats were euthanized, and their bones were analysed by Micro-CT and histology. The healing of bone defect and implant osseointegration in the rats treated with donepezil were significantly reduced compared to the saline-treated rats. Histomorphometric analysis showed lower immune cell infiltration in bone defects treated with donepezil compared to the saline-treated defects. On the other hand, the healing time of soft tissue wounds was significantly shorter in donepezil-treated rats compared to the controls. In conclusion, short-term administration of donepezil hinders bone healing whereas enhancing soft tissue healing.

A diet high in fat and fructose adversely affects osseointegration of titanium implants in rats.

OBJECTIVES: Diet-induced metabolic dysfunction such as type 2 diabetes mellitus increases the risk of implant failure in both dental and orthopaedic settings. We hypothesised that a diet high in fat and fructose would adversely affect peri-implant bone structure and function including osseointegration. MATERIALS AND METHODS: Thirty female Sprague-Dawley rats were divided into three groups (n = 10), control group (normal chow) and two intervention groups on a high-fat (60%), high-fructose (20%; HFHF) diet. Titanium implants were placed in the proximal tibial metaphysis in all groups either before commencing the diet (dHFHF group) or 6 weeks after commencing the diet (HFHF group) and observed for an 8-week healing period. Fasting blood glucose levels (fBGLs) were measured weekly. Structural and functional features of the peri-implant bone, including bone-to-implant contact (BIC), were analysed post euthanasia using microcomputed tomography, pull-out tests, and dynamic histomorphometry. RESULTS: The fBGLs were unchanged across all groups. Peri-implant trabecular bone volume was reduced in the HFHF group compared with controls (p = .02). Percentage BIC was reduced in both HFHF group (25.42 ± 3.61) and dHFHF group (28.56 ± 4.07) compared with the control group (43.26 ± 3.58, p < .05) and reflected the lower pull-out loads required in those groups. Osteoblast activity was reduced in both intervention groups compared with the control group (p < .05). CONCLUSION: The HFHF diet compromised osseointegration regardless of whether the implant was placed before or after the onset of the diet and, despite the absence of elevated fBGLs, confirming that changes in bone cell function affected both the initiation and maintenance of osseointegration independent of blood glucose levels.

Radiographic parameter-driven decision tree reliably predicts aseptic mechanical failure of compressive osseointegration fixation.

Background and purpose - Compressive osseointegration fixation is an alternative to intramedullary fixation for endoprosthetic reconstruction. Mechanical failure of compressive osseointegration presents differently on radiographs than stemmed implants, therefore we aimed to develop a reliable radiographic method to determine stable integration.Patients and methods - 8 reviewers evaluated 11 radiographic parameters from 29 patients twice, 2 months apart. Interclass correlation coefficients (ICCs) were used to assess test-retest and inter-rater reliability. We constructed a fast and frugal decision tree using radiographic parameters with substantial test-retest agreement, and then tested using radiographs from a new cohort of 49 patients. The model's predictions were compared with clinical outcomes and a confusion matrix was generated.Results - 6 of 8 reviewers had non-significant intra-rater ICCs for ≥ one parameter; all inter-rater ICCs were highly reliable (p < 0.001). Change in length between the top of the spindle sleeve and bottom of the anchor plug (ICC 0.98), bone cortex hypertrophy (ICC 0.86), and bone pin hypertrophy (ICC 0.81) were used to create the decision tree. The sensitivity and specificity of the training cohort were 100% (95% CI 52-100) and 87% (CI 74-94) respectively. The decision tree demonstrated 100% (CI 40-100) sensitivity and 89% (CI 75-96) specificity with the test cohort.Interpretation - A stable spindle length and at least 3 cortices with bone hypertrophy at the implant interface predicts stable osseointegration; failure is predicted in the absence of bone hypertrophy at the implant interface if the pin sites show hypertrophy. Thus, our decision tree can guide clinicians as they follow patients with compressive osseo-integration implants.

Alloying design of biodegradable zinc as promising bone implants for load-bearing applications.

Magnesium-based biodegradable metals (BMs) as bone implants have better mechanical properties than biodegradable polymers, yet their strength is roughly less than 350 MPa. In this work, binary Zn alloys with alloying elements Mg, Ca, Sr, Li, Mn, Fe, Cu, and Ag respectively, are screened systemically by in vitro and in vivo studies. Li exhibits the most effective strengthening role in Zn, followed by Mg. Alloying leads to accelerated degradation, but adequate mechanical integrity can be expected for Zn alloys when considering bone fracture healing. Adding elements Mg, Ca, Sr and Li into Zn can improve the cytocompatibility, osteogenesis, and osseointegration. Further optimization of the ternary Zn-Li alloy system results in Zn-0.8Li-0.4Mg alloy with the ultimate tensile strength 646.69 ± 12.79 MPa and Zn-0.8Li-0.8Mn alloy with elongation 103.27 ± 20%. In summary, biocompatible Zn-based BMs with strength close to pure Ti are promising candidates in orthopedics for load-bearing applications.

Mechanical instability induces osteoclast differentiation independent of the presence of a fibrous tissue interface and osteocyte apoptosis in a rat model for aseptic loosening.

Background and purpose - Insufficient initial fixation or early micromotion of an implant is associated with a thin layer of fibrous tissue at the peri-implant interface. It is unknown if bone loss is induced by the fibrous tissue interface acting as an active biological membrane, or as a membrane that will produce supraphysiologic fluid flow conditions during gait, which activates the mechanosensitive osteocytes to mediate osteoclast differentiation. We investigated whether mechanically induced osteolysis is dependent on the fibrous tissue interface as a biologically active scaffold, or if it merely acts as a conduit for fluid flow, affecting the mechanosensitive osteocytes in the peri-prosthetic bone.Methods - Using a rat model of mechanically instability-induced aseptic loosening, we assessed whether the induction of osteoclast differentiation was dependent on the presence of a peri-implant fibrous interface. We analyzed the amount of osteoclast differentiation, osteocyte apoptosis, pro-resorptive cytokine expression and bone loss using immunohistochemistry, mRNA expression and micro-CT.Results - Osteoclast differentiation and bone loss were induced by mechanical instability but were not affected by the presence of the fibrous tissue membrane or associated with osteocyte apoptosis. There was no increased mRNA expression of any of the cytokines in the fibrous tissue membrane compared with the peri-implant bone.Interpretation - Our data show that the fibrous tissue membrane in the interface plays a minor role in inducing bone loss. This indicates that the peri-implant bone adjacent to loose bone implants might play an important role for osteoclast differentiation.

The impact of maintenance on peri-implant health.

Most of the literature evaluating dental implants focuses on implant survival, which is a limited proxy for the successful rehabilitation of patients with missing teeth. Success should include not only survival but also lack of mechanical, biological, and esthetics problems. A comprehensive review of local and systemic risk factors prior to implant placement will allow the tailoring of treatment planning and maintenance protocols to the patient's profile in order to achieve longitudinal success of the therapy. This review discusses the role of controlling different risk factors and prevention/treatment of peri-implant mucositis in order to avoid peri-implantitis. Although the literature addressing the topic is still scarce, the existing evidence shows that performing optimal plaque control and regular visits to the dentist seem to be adequate to prevent peri-implant lesions. Due to impossibility of defining a probing depth associate with peri-implant health, radiographic evaluations may be considered in the daily practice. So far, there is a strong evidence linking a past history of periodontal disease to peri-implant lesions, but this is not so evident for other factors including smoking and diabetes. The prevention of biological complications starts even before implant placement and include a broader analysis of the patient risk profile and tailoring the rehabilitation and maintenance protocols accordingly. It should be highlighted that the installation of implants does not modify the patient profile, since it does not modify genetics, microbiology or behavioral habits of any individual.

Elastography of the bone-implant interface.

The stress distribution around endosseous implants is an important determinant of the surgical success. However, no method developed so far to determine the implant stability is sensitive to the loading conditions of the bone-implant interface (BII). The objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. An acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped implants and to measure the ultrasonic response of the BII during compression. The biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of -4.82 GPa-1. The results may be explained by an increase of the bone-implant contact ratio and by changes of bone structure occurring during compression. The sensitivity of the QUS response of the BII to compressive stresses opens new paths in the elaboration of patient specific decision support systems allowing surgeons to assess implant stability that should be developed in the future.

Can polyaryletherketone cage be used to achieve union and maintain correction in anterior calcaneal lengthening osteotomy for treatment of flexible flatfoot?

A structural graft is often used to maintain correction and achieve union after anterior calcaneal lengthening osteotomy for treatment of flexible flatfoot. Autograft, the current gold standard, is limited in availability and configuration and is associated with donor site morbidity in as much as 48%, whereas the alternative allograft carries risks of disease transmission and collapse. Polyaryletherketone cage, with a healing rate similar to that of autograft, high stability, and no donor-site morbidity, has been used in spine surgery. However, its use has not been documented in foot and ankle surgery. We reviewed 15 patients with painful flatfeet after failure of conservative treatment who were treated by anterior calcaneal lengthening osteotomy using polyaryletherketone cage instead of bone graft. Minimum follow-up was 1 year (average, 1.27 years; range, 1-1.5 years). The male-female ratio was 1:1.5 (six males, nine females). Mean age at time of surgery was 10.8 ± 1.7 years (range, 8-13.5 years). Minimum follow-up was 1 year (average, 1.27 years; range, 1-1.5 years). Nine patients had a unilateral procedure and three had a simultaneous bilateral procedure, for a total of 15 operated feet (seven right and eight left). The paired t-test result was statistically significant in comparison of radiographic measurements at presurgery and postsurgery with P value <0.001. All cases showed full union clinically and radiographically at last follow-ups and no complications occurred. Our data suggest that polyaryletherketone cage may be used as a structural graft option for anterior calcaneal lengthening osteotomy.

Effect of mussel adhesive protein coating on osteogenesis in vitro and osteointegration in vivo to alkali-treated titanium with nanonetwork structures.

Purpose: On the basis of reasonable superposition of various surface treatment methods, alkali-treated titanium with nanonetwork structures (TNS) was coated with mussel adhesive protein (MAP) and named TNS-MAP. The aims were to optimize the biological properties of TNS, endue it with new properties, and enhance its utility in clinical dental applications. Methods: TNS disks were coated with MAP and the product surface was characterized. Its osteogenic properties were determined by evaluating its effects on cell adhesion, cell proliferation, the expression of osteogenesis-related genes, and in vivo experiments. Results: The treated materials showed excellent hydrophilicity, good surface roughness, and advantages of both TNS and MAP. TNS-MAP significantly promoted initial cell attachment especially after 15 mins and 30 mins. At every time point, cell adhesion and proliferation, the detection rate of osteogenesis-related markers in the extracellular matrix, and the expression of osteogenesis-related genes were markedly superior on TNS-MAP than the control. The in vivo experiments revealed that TNS-MAP promoted new bone growth around the implants and the bone-implant interface. Conclusion: We verified through in vitro and in vivo experiments that we successfully created an effective TNS-MAP composite implant with excellent biocompatibility and advantages of both its TNS and MAP parent materials. Therefore, the new biocomposite implant material TNS-MAP may potentially serve in practical dentistry and orthopedics.

Four Stable and Functioning Dental Implants Retrieved for Fracture After 14 and 17 Years from the Same Patient: A Histologic and Histomorphometric Report.

The aim of the present study was a histologic and histomorphometric analysis of the peri-implant tissue reactions and of the bone-titanium interface in successfully osseointegrated, clinically stable, and immobile retrieved titanium dental implants after a long loading period. Four successfully osseointegrated and stable implants with a sandblasted surface were retrieved from a patient due to fracture, two after 14 years of loading and two after 17 years. None of these implants has been previously reported. Mature, compact bone with a few marrow spaces was observed around all four implants. At low magnification, a high percentage of bone-implant contact (BIC) was present at the interface of almost all implants. BIC percentage for the four implants was 83%, 66%, 74%, and 65%. In almost all the implants, the space within the threads was almost completely filled by compact bone. Close, tight contact between bone and implant surface was observed in all specimens, and no gaps or fibrous connective tissue was found at the bone-implant interface. All implants appeared to be well integrated in the surrounding mineralized bone, and all showed adequate BIC percentages after a long loading history.

The impact of maintenance on peri-implant health

Abstract Most of the literature evaluating dental implants focuses on implant survival, which is a limited proxy for the successful rehabilitation of patients with missing teeth. Success should include not only survival but also lack of mechanical, biological, and esthetics problems. A comprehensive review of local and systemic risk factors prior to implant placement will allow the tailoring of treatment planning and maintenance protocols to the patient's profile in order to achieve longitudinal success of the therapy. This review discusses the role of controlling different risk factors and prevention/treatment of peri-implant mucositis in order to avoid peri-implantitis. Although the literature addressing the topic is still scarce, the existing evidence shows that performing optimal plaque control and regular visits to the dentist seem to be adequate to prevent peri-implant lesions. Due to impossibility of defining a probing depth associate with peri-implant health, radiographic evaluations may be considered in the daily practice. So far, there is a strong evidence linking a past history of periodontal disease to peri-implant lesions, but this is not so evident for other factors including smoking and diabetes. The prevention of biological complications starts even before implant placement and include a broader analysis of the patient risk profile and tailoring the rehabilitation and maintenance protocols accordingly. It should be highlighted that the installation of implants does not modify the patient profile, since it does not modify genetics, microbiology or behavioral habits of any individual.

Bone quality, and the combination and penetration of cement-bone interface: A comparative micro-CT study of osteoarthritis and rheumatoid arthritis.

To compare the microstructure, bone quality, and the combination and penetration of cement-bone interface in tissue specimens from patients with osteoarthritis (OA) and rheumatoid arthritis (RA).A total of 80 femoral condyle tissue specimens from 20 OA patients (40 condyles) and 20 RA patients (40 condyles) who underwent total knee arthroplasty at the Department of Orthopaedics in Tengzhou Central People's Hospital were collected between January 2017 and September 2017. According to the random number table method, 20 specimens from the OA group were defined as group A, and 20 specimens in the RA group were defined as group B. The bone quality parameters were measured by micro-CT. The remaining 20 specimens in the OA group and the remaining 20 specimens in the RA group were defined as group C and group D, the cement-bone interfaces were established by the self-made bone cement compression device, and were analyzed by micro-CT.Micro-CT measurement revealed that the bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N) in group A were significantly higher than those in group B (all P < .05). The bone surface/bone volume (BS/BV), structure model index (SMI), trabecular separation (Tb.Sp), and degree of anisotropy (DA) in group A were significantly lower than those in group B (all P < .05). The penetration depth of bone cement in group D was significantly greater than those in group C via x-ray detection.The bone quality of OA patients is better than that of RA patients, but the combination and penetration of cement-bone interface of RA patients are better than that of OA patients. The findings advance our understanding of knee prosthesis and have important clinical implications, but they require validations in future studies with larger sample sizes.

Virtual histology uncertainty in synchrotron x-ray micro-computed tomography evaluation.

A three-dimensional (3D) X-ray tomogram evaluation gives a full view of the bone distribution around an entire implant in contrast to the often-used two-dimensional (2D) histological methods. High-resolution X-ray absorption tomography was used to evaluate the 3D bone growth around dental implants in an experimental goat mandible reconstruction model. The tomograms allowed for the construction of virtual histological cross-sections that could be used to evaluate the statistical uncertainty of the histological methods, which was the purpose of this paper. The virtual 2D histological results showed a significantly higher uncertainty within the same sample than did the full 3D volume results.

The Influence of the Crown-Implant Ratio on the Crestal Bone Level and Implant Secondary Stability: 36-Month Clinical Study.

INTRODUCTION: When the era of dental implantology began, the pioneers defined some gold standards used in dental prosthetics treatment for implant-supported restorations. Referring to traditional prosthetics, it was taken for granted that the length of an implant placed in the alveolar bone (the equivalent of the root) should exceed the length of the superstructure. AIM OF THE STUDY: The aim of the study was to determine whether implant length and the crown-to-implant (C/I) ratio influence implant stability and the loss of the surrounding marginal bone and whether short implants can be used instead of sinus augmentation procedures. MATERIAL AND METHODS: The patients participating in the study (n = 30) had one single tooth implant, a short (OsseoSpeed™ L6 Ø4 mm, Implants) or a regular implant (OsseoSpeed L11 and L13 Ø4 mm, DENTSPLY Implants), placed in the maxilla. The evaluation was based on clinical and radiological examination. The crown-to-implant ratio was determined by dividing the length of the crown together with the abutment by the length of the implant placed crestally. Mean crown-to-implant ratios were calculated separately for each group and its correlation with the MBL (marginal bone loss) and stability was assessed. The authors compared the correlation between the C/I ratio values, MBL, and secondary implant stability. RESULTS: Positive results in terms of primary and secondary stability were achieved with both (short and conventional) implants. The MBL was low for short and conventional implants being 0.34 ± 0.24 mm and 0.22 ± 0.46 mm, respectively. No significant correlation was found between the C/I ratio and secondary stability as well as the C/I ratio and the marginal bone loss. CONCLUSIONS: Short implants can be successfully used to support single crowns. The study has revealed no significant differences in the clinical performance of prosthetic restorations supported by short implants. Clinical trial registration number is NCT03471000.