Reflection of an ultrasonic wave on the bone-implant interface: Comparison of two-dimensional and three-dimensional numerical models.

Quantitative ultrasound is used to characterize osseointegration at the bone-implant interface (BII). However, the interaction between an ultrasonic wave and the implant remains poorly understood. Hériveaux, Nguyen, and Haiat [(2018). J. Acoust. Soc. Am. 144, 488-499] recently employed a two-dimensional (2D) model of a rough BII to investigate the sensitivity of the ultrasonic response to osseointegration. The present letter aimed at assessing the validity of the 2D assumption. The values of the reflection coefficient of the BII obtained with two and three-dimensional models were found not to be significantly different for implant roughness lower than 20 µm. 2D modeling is sufficient to describe the interaction between ultrasound and the BII.

Hard and soft tissue changes around implants activated using plasma of argon: A histomorphometric study in dog.

OBJECTIVE: To histologically assess the hard and soft tissue changes after insertion of cleaned and activated titanium implants using plasma of argon. MATERIALS AND METHODS: Eight dogs were included in this study. The mandibular premolars and first molars were extracted. For each hemi-mandible, four implants, 7 mm long and 3.3 mm of diameter, with a ZirTi surface were used. The surface of two implants was randomly treated with argon plasma (test), while the other two implants were left untreated (control). After 1 month, the same procedure was performed in the contralateral hemi-mandible. The amount of old bone, new bone, overall value of old bone plus new bone, and soft tissue was histologically evaluated. RESULTS: After 1 month of healing, high percentages of new bone in close contact with the implant surface were found at both the treated (60.1% ± 15.6%; 95% CI 56.5%-78.0%) and untreated (57.2% ± 13.1%; 95% CI 49.3%-67.5%) implants. Low percentages of old bone were found at this stage of healing, at both the treated (4.4% ± 3.0%; 95% CI 1.2%-5.4%) and untreated (3.4% ± 3.1%; 95% CI 0.6%-4.9%) implants. Not statistically significant differences were found between groups (p > .05). After 2 months of healing, treated implants presented a significantly higher (p = .012) new bone formation (72.5% ± 12.4%; 95% CI 69.6%-86.8%) compared to untreated sites (64.7% ± 17.3%; 95% CI 59.4%-83.3%). Controversially, no difference (p = .270) in terms of old bone was present between treated (3.1% ± 1.7%, 95% CI 1.8%-4.2%) and untreated implants (3.8% ± 1.9%, 95% CI 3.2%-5.8%). Significant differences (p = .018) in terms of total mineralized bone were found between treated (75.6% ± 13.0%, 95% CI 73.3%-91.3%) and untreated implants (68.4% ± 16.8%; 95% CI 64.2%-87.6%). CONCLUSIONS: Implants treated using plasma of argon was demonstrated to reach a higher bone-to-implant contact when compared to untreated implants.

Fabrication of a Biodegradable Implant with Tunable Characteristics for Bone Implant Applications.

Biodegradable polymers are appealing material for the manufacturing of surgical implants as such implants break down in vivo, negating the need for a subsequent operation for removal. Many biocompatible polymers produce acidic breakdown products that can lead to localized inflammation and osteolysis. This study assesses the feasibility of fabricating implants out of poly(propylene carbonate) (PPC)-starch that degrades into CO2 and water. The basic compression modulus of PPC-starch (1:1 w/w) is 34 MPa; however, the addition of glycerol (1% w/w) and water as plasticizers doubles this value and enhances the surface wettability. The bioactivity and stiffness of PPC-starch blends is increased by the addition of bioglass microparticles (10% w/w) as shown by in vitro osteoblast differentiation assay and mechanical testing. MicroCT analysis confirms that the bioglass microparticles are evenly distributed throughout biomaterial. PPC-starch-bioglass was tested in vivo in two animal models. A murine subcutaneous pellet degradation assay demonstrates that the PPC-starch-bioglass blend's volume fraction loss is 46% after 6 months postsurgery, while it is 27% for poly(lactic acid). In a rat knee implantation model, PPC-starch-bioglass screws inserted into the distal femur show osseointegration with no localized adverse effects after 3 and 12 weeks. These data support the further development of PPC-starch-bioglass as a medical biomaterial.

Correlation between pre-operative buccal bone thickness and soft tissue changes around immediately placed and restored implants in the maxillary anterior region: A 2-year prospective study.

OBJECTIVES: This study evaluated the correlation between pre-operative buccal cortical bone thickness and peri-implant tissue response following immediate placement and restoration of implants in the maxillary aesthetic zone. MATERIAL AND METHODS: Eighteen patients (3 males, 15 females) with an age range of 19-57 years requiring the replacement of a single maxillary anterior tooth were included in this prospective study. Patients were selected on the basis of defined criteria: intact socket walls, absence of any acute infection in the sockets, absence of any gingival marginal pathology and attainment of a high primary stability (≥30 Ncm) at implant placement. Regardless of buccal bone thickness, all participating patients underwent the same treatment strategy that involved removal of the failed tooth, flapless surgery, immediate implant placement, grafting of the implant-socket gap and connection of a screw-retained provisional restoration. Buccal bone thickness was evaluated using pre-operative CBCT scans. Intra-oral photographs were taken before implant placement (baseline) and at 1- and 2-year follow-up to assess soft tissue changes around the implants. Aesthetic evaluation was carried out using the pink esthetic score (PES). RESULTS: All implants remained osseointegrated during the follow-up period of 2 years with mesial papilla, distal papilla, and mid-facial gingiva showing a mean recession of 0.06 ± 0.71 mm, 0.25 ± 0.78 mm, and 0.22 ± 0.83 mm, respectively. Pink esthetic score values improved from a median value of 9 (IQR 8.75-10.25) pre-operatively to 11 (IQR 9.75-12) at the end of 2 years. No significant correlation was found between buccal bone thickness (range 0.45-1.24 mm) and soft tissue or aesthetic changes. CONCLUSIONS: Within the limits of this study, no significant correlation could be found between pre-operative buccal bone width and the soft tissue and aesthetic outcome following immediate implant placement and restoration in the anterior maxilla. Therefore, favourable clinical and aesthetic outcomes could be achieved by applying a strict selection criteria and treatment protocol regardless of the initial thickness of the buccal bone.

Influence of Implants Surface Properties on Bone Tissue Formation in the Ectopic Osteogenesis Test.

We studied the influence of the characteristics of oxide porous coatings on osteogenesis and integration of new bone tissue and titanium implant surface in the ectopic osteogenesis test. Implants with coating with pore size 2-20 µ exhibit better osteogenic and osteoconductive characteristics than implants with homogenous surface and smooth relief (pore size 0.5-5.0 µ). Physical characteristics of the surface of the material along with chemical composition of the coating are essential for the formation of bone tissue and its integration with the implant.

Biograft Block Hydroxyapatite: A Ray of Hope in the Reconstruction of Maxillofacial Defects.

BACKGROUND: Improving quality of human life has been the rationale for increase in the applications of bone substitute materials for bone regeneration. High prevalence of loss of bone tissue due to disease remains a major challenge for reconstruction. Shortcomings of autografts and allografts have made the clinicians go for artificial implant materials. AIM AND OBJECTIVE: To prospectively study the structural and esthetic reconstruction of resected mandibular site with biograft porous block hydroxyapatite (BBHA). The study evaluated the efficacy of BBHA as a material for reconstruction of large bone defects. METHODS: Patients requiring reconstruction after resection of cyst/tumors and who denied conventional reconstruction were enrolled for BBHA reconstruction during 2008 to 2015. All patients were clinically and radiologically followed and assessed for a range of 4 to 60 months for outcome. RESULTS: During follow-up periods no one had infection, dissolution, migration, or absorption, but new bone formation and bridging observed in proximity with graft and bone interface. CONCLUSION: Structural and esthetic reconstruction using BBHA significantly reduces donor site morbidity. BBHA have satisfactory results in relation to esthetics and are useful material for reconstruction. Clinical application of this technique will minimize an additional surgical procedure required to harvest donor bone. BBHA provides good esthetics and structural balance to face. As this is an ongoing study the outcome is expected to improve. The incorporation of implants in the BBHA block may fulfill the function also in near future.

Evaluation of the surface characteristics of anodic oxidized miniscrews and their impact on biomechanical stability: An experimental study in beagle dogs.

INTRODUCTION: In this study, we aimed to assess the surface characteristics and the biomechanical stability of miniscrews with an anodic oxidized surface compared with machined surface miniscrews in beagle dogs. METHODS: Self-drilled, titanium-aluminum-vanadium alloy miniscrews with an anodic oxidized surface (n = 48) or a machined surface (n = 48) were placed into the mandibles of 12 beagle dogs. The surface characteristics of both types of miniscrews were analyzed before implantation with scanning electron microscopy and atomic force microscopy. Insertion torque was measured during placement of all 96 miniscrews. Half of the implants in each group (24 specimens per subgroup) received 200 to 250 g of tensile force for 3-week or 12-week loading periods. Removal torque was measured in 12 specimens of each subgroup, and bone-implant contact and bone volume were quantified in the other 12 specimens of each subgroup. RESULTS: Atomic force microscopy measurements demonstrated that the anodic oxidized surface miniscrews had significantly higher roughness parameters than did the machined surface miniscrews (P < 0.001). The 2 types of miniscrews were not significantly different in insertion and removal torque values or in bone-implant contacts and bone volumes, regardless of the loading period. CONCLUSIONS: Anodic oxidized miniscrews have different surface roughness profiles but no clinically significant superiority in biomechanical stability compared with machined surface miniscrews.

Laser-treated stainless steel mini-screw implants: 3D surface roughness, bone-implant contact, and fracture resistance analysis.

BACKGROUND/OBJECTIVES: This study investigated the biomechanical properties and bone-implant intersurface response of machined and laser surface-treated stainless steel (SS) mini-screw implants (MSIs). MATERIAL AND METHODS: Forty-eight 1.3mm in diameter and 6mm long SS MSIs were divided into two groups. The control (machined surface) group received no surface treatment; the laser-treated group received Nd-YAG laser surface treatment. Half in each group was used for examining surface roughness (Sa and Sq), surface texture, and facture resistance. The remaining MSIs were placed in the maxilla of six skeletally mature male beagle dogs in a randomized split-mouth design. A pair with the same surface treatment was placed on the same side and immediately loaded with 200 g nickel-titanium coil springs for 8 weeks. After killing, the bone-implant contact (BIC) for each MSI was calculated using micro computed tomography. Analysis of variance model and two-sample t test were used for statistical analysis with a significance level of P <0.05. RESULTS: The mean values of Sa and Sq were significantly higher in the laser-treated group compared with the machined group (P <0.05). There were no significant differences in fracture resistance and BIC between the two groups. LIMITATION: animal study CONCLUSIONS/IMPLICATIONS: Laser treatment increased surface roughness without compromising fracture resistance. Despite increasing surface roughness, laser treatment did not improve BIC. Overall, it appears that medical grade SS has the potential to be substituted for titanium alloy MSIs.

Capacity of dental equipment to interfere with cardiac implantable electrical devices.

Patients with cardiac implantable electrical devices should take precautions when exposed to electromagnetic fields. Possible interference as a result of proximity to electromagnets or electricity flow from electronic tools employed in clinical odontology remains controversial. The objective of this study was to examine in vitro the capacity of dental equipment to provoke electromagnetic interference in pacemakers and implantable cardioverter defibrillators. Six electronic dental instruments were tested on three implantable cardioverter defibrillators and three pacemakers from different manufacturers. A simulator model, submerged in physiological saline, with elements that reproduced life-size anatomic structures was used. The instruments were analyzed at differing distances and for different time periods of application. The dental instruments studied displayed significant differences in their capacity to trigger electromagnetic interference. Significant differences in the quantity of registered interference were observed with respect to the variables manufacturer, type of cardiac implant, and application distance but not with the variable time of application. The electronic dental equipment tested at a clinical application distance (20 cm) provoked only slight interference in the pacemakers and implantable cardioverter defibrillators employed, irrespective of manufacturer.

Torque Analysis of a Triple Acid-Etched Titanium Implant Surface.

The present study aimed to evaluate the removal torque of titanium implants treated with triple acid etching. Twenty-one rats were used in this study. For all animals, the tibia was prepared with a 2 mm drill, and a titanium implant (2 × 4 mm) was inserted after treatment using the subtraction method of triple acid etching. The flaps were sutured. Seven animals were killed 14, 28, and 63 days after implant installation, and the load necessary for removing the implant from the bone was evaluated by using a torque meter. The torque values were as follows: 3.3 ± 1.7 Ncm (14 days), 2.2 ± 1.3 Ncm (28 days), and 6.7 ± 1.4 Ncm (63 days). The torque value at the final healing period (63 days) was statistically significantly different from that at other time points tested (ANOVA, p = 0.0002). This preliminary study revealed that treatment with triple acid etching can create a promising and efficient surface for the process of osseointegration.

Histomorphological and torque removal comparison of 6 mm orthodontic miniscrews with and without surface treatment in New Zealand rabbits.

AIM: The purpose of this study was to assess the difference of removal torque values (RTV) and the bone-to-implant contact (BIC) between the sand-blasted, large grit, and acid-etched (SLA) surface-treated and the machined surface (MA) miniscrews. MATERIAL AND METHODS: Miniscrews used in this study were 6mm long with a diameter of 1.5mm. A total of 23 SLA miniscrews and 24 MA miniscrews were placed into the distal femoral condyle of 24 New Zealand rabbits. Removal torque test and the BIC was histologically evaluated at 0 and 8 weeks. RESULTS: There was no statistical difference between the RTV in the MA group versus the SLA group at both 0 and 8 weeks. Comparing 0-8 weeks, there was no significant difference in RTV of the SLA group (P = 0.48), however the change in the MA group was statistically significant (P = 0.006). Histological observation showed a significant decrease in BIC comparing 0 and 8 weeks for the MA group. The BIC ratio at 8 weeks was statistically significantly higher in the SLA group compared to the MA group. CONCLUSION: SLA surface preparation does not increase the RTV of miniscrews. Further investigations under loading and a large sample size are required.

Biomechanical and histomorphometric properties of four different mini-implant surfaces.

OBJECTIVES: To investigate the effects of surface roughness on the removal torque and bone-to-implant contact of four different orthodontic mini-implants. MATERIALS AND METHODS: Mini-implants and circular discs were made from alloy Ti6Al4V grade 5. On the basis of surface treatment, the study was divided into four groups-group 1: machined (n = 32), no surface treatment; group 2: acid etched (n = 32), with hydrochloric acid; group 3 (n = 32), grit blasted with alumina; and group 4, grit blasted + acid etched (n = 32). Mean surface roughness (Ra) and quadratic average roughness (Rq) from each group were measured two dimensionally in non-contact mode by the optical profilometer. Contact angle measurement of discs from each group was done with a contact angle goniometer. Contact angle of liquids with different hydrophobicity and hydrophilicity was measured: 1. highly hydrophilic liquid sodium chloride (NaCl), 2. lightly hydrophobic liquid dimethylsulfoxide, 3. distilled water, and 4. human blood. One hundred and twenty-eight miniscrews, differing in surface treatment, were placed into the tibias and femurs of adult male New Zealand white rabbits. Rabbits were euthanized after 8 weeks and removal torque and bone-to-implant contact were measured. RESULTS: Surface roughness of group 3 was significantly greater than other groups (P < 0.05). Group 4 had significantly lower contact angle measurements, both for blood and sodium chloride (NaCl; 40.26 degrees, 27.20 degrees) when compared to other three groups (P ≤ 0.01). Group 4 had significantly higher torque and bone-to-implant contact than group 3 (P = 0.007), group 2 (P = 0.003), and group 1 (P = 0.0002). CONCLUSION: Surface roughness and wettability of mini-implants influence their biological response.

Orthodontic miniscrews: an experimental campaign on primary stability and bone properties.

OBJECTIVE: To evaluate the primary stability of different shaped miniscrews through the acquisition of data regarding maximum insertion torque, pullout force, and a radiodiagnosic evaluation of bone characteristics. MATERIALS AND METHODS: Sixty fresh porcine bone samples were scanned by computed tomography (CT) and cone-beam computed tomography (CBCT). By means of a dedicated software, CT and CBCT images were analysed to measure the insertion-site cortical thickness, cortical density, and marrow bone density. Sixty miniscrews of 12 different types were implanted with no predrilling pilot hole in the bone samples. Every device was tightened by means of a digital torque screwdriver and torque data were collected. Subsequently, pullout tests were performed. Spearman and Pearson correlations were employed to compare any relationship between continuous variables. RESULTS: Different types of miniscrews did not show statistically significant differences in their torque value (P = 0.595), instead a significant difference was revealed by considering their load measures (P = 0.039). Cortical bone thickness resulted strongly correlated both with value of load (P < 0.001), and modestly with torque measures (P = 0.004). A strong positive correlation was found between CT and CBCT both for cortical density (P < 0.001) and marrow bone density (P < 0.001). CONCLUSION: Bone characteristics play the major role in miniscrews primary stability.

The comparison between implant stability quotient and bone-implant contact revisited: an experiment in Beagle dog.

BACKGROUND: Resonance frequency analysis (RFA) is applied clinically for the assessment of implant stability, and the relevance of this application is widely accepted. However, the relationship between resonance frequency (RF) and other parameters of implant stability, such as the histomorphometrical bone-to-implant contact (BIC) parameter, has become controversial in the last decade. OBJECTIVE: To analyse and clarify the controversial relationship between RF and histomorphometrical BIC measurements. MATERIAL AND METHODS: A total of 36 dental implants (9 mm length, Ø 4.0 mm; Biohorizons(®) Implant Systems Inc., Birmingham, AL, USA) with a soluble blasting media (sandblasting with soluble particles) surface were implanted in six beagle dog mandibles. RFA assessments were performed with a magnetic Osstel Mentor(®) device at the time of implant installation, and during the monitoring period at weeks 1, 2, 4, 6 and 8, before implant retrieval. The dogs were sacrificed and the implants were removed in block after 8, 6, 4, 2, 1 and 0 weeks, respectively. One group was obtained at time 0, immediately after the implantation. The samples were embedded in methyl methacrylate polymers (Technovit(®) ) and cut along their long axis. BIC values were assessed by a non-subjective and systematic method based on backscattered scanning electron microscopy (BS-SEM) images. BIC% at the different time points was compared with the corresponding implant stability quotient (ISQ) values of the RFA assessment. RESULTS: No statistically significant correlation between BIC and ISQ values (Osstell Mentor(®) ) was identified. The absence of a relationship between these two parameters is in agreement with several previous studies in humans and experimental animals. CONCLUSIONS: The lack of correlation between BIC and ISQ values suggests that ISQ as determined by RFA is not able to identify the relationship between RF and histomorphometrical data.

Evaluation of a new experimental model to study bone healing after ridge expansion with simultaneous implant placement--a pilot study in minipigs.

OBJECTIVE: To evaluate the suitability of a minipig model for the study of bone healing and osseointegration of dental implants following bone splitting and expansion of narrow ridges. MATERIAL AND METHODS: In four minipigs, the mandibular premolars and first molars were extracted together with removal of the buccal bone plate. Three months later, ridge splitting and expansion was performed with simultaneous placement of three titanium implants per quadrant. On one side of the mandible, the expanded bone gap between the implants was filled with an alloplastic biphasic calcium phosphate (BCP) material, while the gap on the other side was left unfilled. A barrier membrane was placed in half of the quadrants. After a healing period of 6 weeks, the animals were sacrificed for histological evaluation. RESULTS: In all groups, no bone fractures occurred, no implants were lost, all 24 implants were osseointegrated, and the gap created by bone splitting was filled with new bone, irrespective of whether BCP or a barrier membrane was used. Slight exposure of five implants was observed, but did not lead to implant loss. The level of the most coronal bone-to-implant contact varied without being dependent on the use of BCP or a barrier membrane. In all groups, the BCP particles were not present deep in the bone-filled gap. However, BCP particles were seen at the crestal bone margin, where they were partly integrated in the new bone. CONCLUSIONS: This new minipig model holds great promise for studying experimental ridge splitting/expansion. However, efforts must be undertaken to reduce implant exposure and buccal bone resorption.

The effect of implant diameter on osseointegration utilizing simplified drilling protocols.

OBJECTIVES: To observe and to compare histologically and histomorphometrically, the combined effect of drilling sequence and implant diameter in vivo. MATERIAL AND METHODS: A total of 72 alumina-blasted and acid-etched Ti-6Al-4V implants with three different diameters (3.75, 4.2, and 5 mm, n = 24 for each group) were placed in the right and left tibiae of 12 beagle dogs. Within the same diameter group, half of the implants were inserted after a simplified drilling procedure (pilot drill + final diameter drill) on one tibia and the other half were placed using the conventional drilling procedure on the other tibia. After 1 week, half of the animals (n = 6) were sacrificed, and the other half was sacrificed after 5 weeks (n = 6). The retrieved bone-implant samples were subjected to non-decalcified histologic sectioning, and the bone-to-implant contact (BIC) and the bone area fraction occupancy (BAFO) were analyzed. Primary statistical analysis used a mixed model analysis of variance with significance level set at P < 0.05. RESULTS: Histologic observation showed that at 1 week, immature woven bone formed in vicinity of the implant, whereas at 5 weeks, the woven bone was replaced by lamellar bone, which formed in proximity with the implant. Histomorphometrically, the simplified technique was associated with significantly greater BIC and BAFO after 1 week. Differences between techniques were not longer apparent after 5 weeks, but BAFO was inversely and significantly associated with implant diameter at that time. CONCLUSIONS: The simplified technique did not impair either early or late bone formation for any tested implant diameter; however, wider diameters were associated with less bone formation at longer healing times for both techniques.

Early molecular assessment of osseointegration in humans.

OBJECTIVE: To determine the early temporal-wide genome transcription regulation by the surface topography at the bone-implant interface of implants bearing microroughened or superimposed nanosurface topology. MATERIALS AND METHODS: Four commercially pure titanium implants (2.2 × 5.0 mm) with either a moderately roughened surface (TiOblast) or super-imposed nanoscale topography (Osseospeed) were placed (n = 2/surface) in edentulous sites of eleven systemically healthy subjects and subsequently removed after 3 and 7 days. Total RNA was isolated from cells adherent to retrieved implants. A whole-genome microarray using the Affymetrix Human gene 1.1 ST Array was used to describe the gene expression profiles that were differentially regulated by the implant surfaces. RESULTS: There were no significant differences when comparing the two implant surfaces at each time point. However, the microarray identified several genes that were differentially regulated at day 7 vs. day 3 for both implant surfaces. Functionally relevant categories related to the extracellular matrix (ECM), collagen fibril organization, and angiogenesis were upregulated at both surfaces (day7 vs. day3). Abundant upregulation of several differential markers of alternative activated macrophages was observed (e.g., MRC1, MSR1, MS4A4A, SLC38A6, and CCL18). The biological processes involved with the inflammatory/immune response gene expression were concomitantly downregulated. CONCLUSIONS: Gene regulation implicating collagen fibrillogenesis and ECM organization as well as the inflammatory/immune responses involving the alternative activated pathway are observed in implant adherent cells at early (3-7 days) after implantation. These gene expression events may indicate a pivotal role of collagen fibrillogenesis as well as immunomodulation in altering bone accrual and biomechanical physical properties of the implant-bone interface.

Histologic and histomorphometric evaluation of peri-implant bone of immediate or delayed occlusal-loaded non-splinted implants in the posterior mandible--an experimental study in monkeys.

OBJECTIVES: The primary aim of this study was to compare the bone reaction around immediate-loaded non-splinted single implants vs. delayed loaded non-splinted single implants placed in healed ridges in the posterior mandible. MATERIALS AND METHODS: Six adult Macaca Fascicularis monkeys were used in this study. The first and second premolars and the first molar were extracted in both sides of the mandible. After 3 months of healing, four implants (Replace Select Tapered; Nobel Biocare, Gothenburg, Sweden) with a moderately rough surface (TiUnite, Nobel Biocare) were placed in the edentulous areas of each monkey, two in each side. The implants had a length of 10 mm and a diameter of 3.5 mm. Four groups of varying time and occlusal loading aspects were created: (i) control group: implant placed non-loaded for 3 months; (ii) immediate loaded: implant placed and loaded immediately for 3 months; (iii) immediate loaded: implant placed and loaded immediately for 6 months; and (iv) delayed loaded: implant placed submerged for 3 months and then loaded for 3 months. At the loaded implants, after a second stage surgery, a composite crown was made directly on an abutment mounted on the implant reinsuring simultaneous occlusal contact on the implant crown and the neighboring teeth. After euthanization of the animals, histologic specimens were quantified in the light microscope. RESULTS: All implants were clinically, radiographically, and histologically osseointegrated at the time of euthanization and with only mild signs of inflammation in the peri-implant mucosa. The histologic marginal bone level was located on average 1.14-1.74 mm apical to the margin of the implants in the various groups. The average bone-to-implant contact (BIC) varied between 55% and 65% and the average bone density (i.e., the proportion of mineralized bone tissue from the implant surface and to a distance of 1 mm lateral to the implant) varied between 30.6% and 34.2%. No statistical significant differences between groups were observed in the above-stated histomorphometric parameters. CONCLUSIONS: Similar histologic and histomorphometric findings were observed in immediately and delayed loaded non-splinted implants placed in the posterior mandible of macaque monkeys.

Surface functionalization of chitosan as a coating material for orthopaedic applications: A comprehensive review.

Metallic implants have dominated the biomedical implant industries for the past century for load-bearing applications, while the polymeric implants have shown great promise for tissue engineering applications. The surface properties of such implants are critical as the interaction of implant surfaces, and the body tissues may lead to unfavourable reactions. Desired implant properties are biocompatibility, corrosion resistance, and antibacterial activity. A polymer coating is an efficient and economical way to produce such surfaces. A lot of research has been carried out on chitosan (CS)-modified metallic and polymer scaffolds in the last decade. Different methods such as electrophoretic deposition, sol-gel methods, dip coating and spin coating, electrospinning, etc. have been utilized to produce CS coatings. However, a systematic review of chitosan coatings on scaffolds focussing on widely employed techniques is lacking. This review surveys literature concerning the current status of orthopaedic applications of CS for the purpose of coatings. In this review, the various preparation methods of coating, and the role of the surface functionalities in determining the efficiency of coatings are discussed. Effect of nanoparticle additions on the polymeric interfaces and in regulating the properties of surface coatings are also investigated in detail.

3-dimensional visualization of implant-tissue interface with the polyethylene glycol associated solvent system tissue clearing method.

OBJECTIVES: Dental implants are major treatment options for restoring teeth loss. Biological processes at the implant-tissue interface are critical for implant osseointegration. Superior mechanical properties of the implant constitute a major challenge for traditional histological techniques. It is imperative to develop new technique to investigate the implant-tissue interface. MATERIALS AND METHODS: Our laboratory developed the polyethylene glycol (PEG)-associated solvent system (PEGASOS) tissue clearing method. By immersing samples into various chemical substances, bones and teeth could be turned to transparent with intact internal structures and endogenous fluorescence being preserved. We combined the PEGASOS tissue clearing method with transgenic mouse line and other labelling technique to investigate the angiogenesis and osteogenesis processes occurring at the implant-bone interface. RESULTS: Clearing treatment turned tissue highly transparent and implant could be directly visualized without sectioning. Implant, soft/hard tissues and fluorescent labels were simultaneously imaged in decalcified or non-decalcified mouse mandible samples without disturbing their interfaces. Multi-channel 3-dimensional image stacks at high resolution were acquired and quantified. The processes of angiogenesis and osteogenesis surrounding titanium or stainless steel implants were investigated. CONCLUSIONS: Both titanium and stainless steel implants support angiogenesis at comparable levels. Successful osseointegration and calcium precipitation occurred only surrounding titanium, but not stainless steel implants. PEGASOS tissue clearing method provides a novel approach for investigating the interface between implants and hard tissue.