Synergistic Effect of Nano Strontium Titanate Coating and Ultraviolet C Photofunctionalization on Osteogenic Performance and Soft Tissue Sealing of poly(ether-ether-ketone).

This study aimed to evaluate the bioactivity of poly(ether ether ketone) (PEEK) after surface modification by persistent photoconductive strontium titanate (SrTiO3) magnetron sputtering and ultraviolet (UV) C irradiation. According to the different modifications, the PEEK specimens were randomly divided into five groups (n = 38/group): PEEK, Sr100-PEEK, Sr200-PEEK, UV/PEEK, and UV/Sr200-PEEK. Then, the specimens of Sr100-PEEK and Sr200-PEEK groups were, respectively, coated with 100 and 200 nm thickness photocatalyst SrTiO3 on the PEEK surface by magnetron sputtering. Subsequently, UV-C light photofunctionalized the specimens of PEEK and Sr200-PEEK groups to form UV/PEEK and UV/Sr200-PEEK groups. The specimens were characterized by a step meter, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), and a water contact angle meter. The release test of the Sr ion was performed by inductively coupled plasma mass spectrometry (ICP-MS). In vitro study, osteogenic activity (MC3T3-E1 osteoblast-like cells) and epithelial and connective tissue attachment (gingival epithelial cells GE1 and fibroblasts NIH3T3) were analyzed in five groups. Surface morphology of the specimens was changed after coating, and the Sr content on the Sr-PEEK surface was increased with increasing coating thickness. In addition, the contact angle was increased significantly after magnetron sputtering. After UV-C photofunctionalization, the content of surface elements changed and the contact angle was decreased. The release of Sr ion was sustained, and the final cumulative release amount did not exceed the safety limit. In vitro experiments showed that SrTiO3 improved the cell activity of MC3T3-E1 and UV-C irradiation further enhanced the osteogenic performance of PEEK. Besides, UV-C irradiation also significantly promoted the cell viability, development, and expression of adhesion proteins of GE1 and NIH3T3 on PEEK. The present investigation demonstrated that nano SrTiO3 coating with UV-C photofunctionalization synergistically enhanced the osteogenic properties and soft tissue sealing function of PEEK in vitro.

Effect of Drilling Preparation on Immediately Loaded Implants: An In Vivo Study in Sheep.

PURPOSE: To determine the biologic and biomechanical effects of two implant drilling protocols on the cortical bone around implants subjected to immediate loading. MATERIALS AND METHODS: A total of 48 implants were inserted into the mandibles of six sheep following one of two drilling protocols: undersized preparation (US; n = 24) and nonundersized preparation (NUS; n = 24). Immediately after implant insertion, an abutment was placed on each implant and 36 implants were subjected to 10 sessions of dynamic vertical loads (1,500 cycles, 1 Hz) of 25 N or 50 N. Insertion torque value (ITV) was recorded at implant installation. Resonance frequency analysis (RFA) was measured at implant insertion and at each loading session. Fluorochrome was administered at day 17, and the animals were euthanized after 5 weeks. The removal torque values (RTVs) were measured, and samples underwent histomorphometric, µCT (microcomputed tomography), and fluorescence image acquisition analyses. The bone volume density (BV/TV), bone-to-implant contact (BIC), bone area fraction occupancy (BAFO), and fluorochrome stained bone surface (MS) were calculated. A linear mixed model analysis was performed, and Pearson paired correlation was calculated. RESULTS: Five implants from the NUS group failed, with a mean ITV of 8.8 Ncm and an RFA value of 57. The mean ITVs for US group and NUS group were 80.5 (± 14) Ncm and 45.9 (± 25) Ncm, respectively (P < .001). No differences were noted in the RFA values from the time of implant insertion until the end of the study. No differences in RTV, BV/TV, BAFO, or MS were observed between the groups. Intense new bone formation took place in the NUS group implants that were subjected to load. CONCLUSIONS: Undersized preparation of cortical bone ensured a greater BIC compared to a nonundersized preparation. Moreover, this study demonstrated that immediate loading did not interfere with the osseointegration process, but loading induced intense new bone formation in the NUS group. It is not recommended to immediately load the implants when the clinically perceived primary stability is lower than an ITV of 10 Ncm and an RFA value of 60. Int J Oral Maxillofac Implants 2023;38:607-618. doi: 10.11607/jomi.9949.

Impact of salivary contamination during implant placement with different surface characteristics in native and augmented bone: An in vivo study in sheep calvaria model.

OBJECTIVES: The aim of this study was to evaluate whether salivary contamination during placement of implants with different surface characteristics affects osseointegration in native and in augmented bone areas. MATERIALS AND METHODS: Forty eight implants with machined surface (MS) and 48 implants with moderately rough surface (RS) were tested in the calvaria of 12 sheep. At the first surgery, 64 bony critical defects were randomly created and were subsequently augmented with two materials (autogenous or bovine bone). After 5 weeks of graft healing, 8 implants were placed per sheep, in native bone and in the centre of the augmented defects. Forty eight implants were soaked with saliva before placement (contaminated group [CG]), while 48 implants were not (non-contaminated group [NCG]). Five weeks after implant placement, bone-to-implant contact (BIC) and bone material area fraction occupancy (BMAFO) were calculated histomorphometrically. RESULTS: Saliva contamination showed a significant negative effect (p = .000) on BIC, especially in augmented areas. RS showed significant positive effect on BIC, compared to MS (p = .000), while there were no significant differences for different bone conditions (p = .103). For BMAFO, the contamination showed a significantly negative affect (p = .000), while there were no significant differences for surface characteristics (p = .322) and for bone condition (p = .538). CONCLUSION: Saliva contamination during dental implant placement has a negative effect on osseointegration in augmented areas. Moderately rough surface has a possible advantage in the aspect of initial bone to implant contact. However, it seems to be advisable to avoid saliva contamination especially for implants placed in augmented bone areas.

Clinical effects of conventional and underprepared drilling preparation of the implant site based on bone density: A systematic review and meta-regression.

PURPOSE: There is no clinical consensus to determine the right balance between underpreparation and marginal bone level changes. The purpose of this systematic review and meta-regression was to investigate the influence of the type of drilling preparation of the implant site in relation to the bone mineral density on the clinical success, expressed in terms of the MBL and implant failure rate. STUDY SELECTION: A thorough search was performed using the digital databases MEDLINE PubMed, EMBASE, and Cochrane Central Register of Controlled Trials by entering research lines or various combinations of free words. The main keywords used were "dental implants", "bone density", and "torque". RESULTS: The mean bone resorption in the conventional preparation group was -0.43 (± 0.28) mm, whereas it was -0.80 (± 0.37) mm in the underprepared group. For the D1/D2/D3 bone group, the slope was significantly different from zero and linearity; the D4 bone group slope was not significantly different from zero and was almost parallel, although it was significantly different from linearity. The box and whiskers plot shows that the MBL in underprepared sites tended to be significantly higher with a higher variation than that in conventionally prepared sites. CONCLUSIONS: Within its limits, our meta-regression analysis showed that MBL is influenced by the type of drilling preparation and bone mineral density. In particular, a lower MBL was observed in the D1 bone with conventional preparation than with underpreparation. Moreover, a greater implant-to-osteotomy site mismatch was positively associated with greater MBLs in the bone densities of D1/D2/D3.

Current surface modification strategies to improve the binding efficiency of emerging biomaterial polyetheretherketone (PEEK) with bone and soft tissue: A literature review.

PURPOSE: The aim of this study was to review the literature on current surface modification strategies used to improve the binding efficiency of an emerging biological material, polyetheretherketone (PEEK), with bone and soft tissues. STUDY SELECTION: This review was based on articles retrieved from PubMed, Google Scholar, Web of Science, and ScienceDirect databases. The main keywords used during the search were "polyetheretherketone (PEEK)," "implant," "surface modification," "biomaterials," "bone," "osseointegration," and "soft tissue." RESULTS: The suitability of PEEK surface modification strategies has been critically analyzed and summarized here. Many cell and in vivo experiments in small animals have shown that the use of advanced modification technologies with appropriate surface modification strategies can effectively improve the surface inertness of PEEK, thereby improving its binding efficiency with bone and soft tissues. CONCLUSIONS: Surface modifications of PEEK have revealed new possibilities for implant treatment; however, most results are based on in vitro or short-term in vivo evaluations in small animals. To achieve a broad application of PEEK in the field of oral implantology, more in vivo experiments and long-term clinical evaluations are needed to investigate the effects of various surface modifications on the tissue integration ability of PEEK to develop an ideal implant material.

Synergistic Effect of Carbonate Apatite and Autogenous Bone on Osteogenesis.

Bone augmentation using artificial bone is an important option in dental defect prostheses. A bone substitute using carbonate apatite (CO3Ap), an inorganic component of bone, was reported to have promising bone formation and bone replacement ability. However, the osteoinductivity of artificial bone is less than autogenous bone (AB). In this study, CO3Ap with AB is demonstrated as a clinically effective bone substitute. For in vitro experiments, an osteoclast-like cell (RAW-D) was cultured in the presence of AB, CO3Ap, or both (Mix), and the number of osteoclasts was evaluated. Osteoblasts were also cultured under the same conditions, and the number of adherent cells was evaluated. For in vivo experiments, a few holes were created in the rat tibia and AB, CO3Ap, or Mix were added. At 0, 14, and 21 days, the tissue morphology of the wound area was observed, and the thickness of the cortical bone was measured. In vitro, Mix did not increase the number of osteoclasts or osteoblasts. However, in vivo, the rate of bone replacement remarkably increased with Mix on dome-shape. A bone-grafting material combining osteoinductive AB with abundant artificial bone is expected to be clinically easy to use and able to form bone.

Impact of a Hydrophilic Dental Implant Surface on Osseointegration: Biomechanical Results in Rabbit.

This study aimed to evaluate the effect of surface hydrophilicity on the biomechanical aspects of osseointegration of dental implants in the tibia and femur of rabbits. Forty-eight mature female New Zealand White rabbits were included, and 96 commercially pure, Grade 4, titanium dental implants (control group), and 96 implants of same macro geometry with the hydrophilic surface (test group) were used in this study. One osteotomy was performed in each tibia and femur on both sides of the rabbit, and four implants were placed in each rabbit. Control and test groups were randomly allocated on the left and right sides. During surgery, insertion torque (ITQ) value of the complete implant placement was recorded. After healing periods of 0, 2, 4, and 8 weeks after surgery, implant stability quotient (ISQ) value, and removal torque (RTQ) values were measured. No statistical difference was observed for ITQ, for ISQ and for RTQ between the control group and test group in tibia/femur for all time periods. The effect of hydrophilic properties on moderately roughened surfaces has no impact in terms of biomechanical outcomes (ISQ values and RTQ values) after a healing period of 2 to 8 weeks in rabbit tibias /femurs.

Localization of Integrin Beta-4 Subunit at Soft Tissue-Titanium or Zirconia Interface.

Currently, along with titanium (Ti), zirconia is widely used as an abutment material for dental implants because it makes it possible to avoid gingival discoloration; however, the epithelial sealing capability of zirconia remains unknown. The purpose of the present study is to elucidate the localization of integrin ß4 subunit (Inß4), one of the main proteins in the attachment structure between gingival junctional epithelial (JE) cells and substrata. Maxillary first molars were extracted from rats, and implants were placed with Ti or zirconia transgingival parts; then, the localization of Inß4 was observed. Morphological and functional changes in rat oral epithelial cells (OECs) cultured on a culture dish (Dish) and Ti and zirconia plates were also evaluated with Inß4 immunofluorescence histochemistry and Western blotting. After four weeks of implant placement, the morphology of the peri-implant epithelium (PIE) and the localization of Inß4 around the Ti and zirconia transgingival parts were similar. However, both exhibited markedly shorter Inß4-positive bands in the PIE than in the JE around natural teeth. Decreased expression levels of Inß4 were observed in OECs cultured on Ti and zirconia plates compared with those cultured on Dish. In conclusion, although inferior to natural teeth, zirconia implants are thought to have epithelial sealing properties comparable to those of titanium.

In silico multi-scale analysis of remodeling peri-implant cortical bone: a comparison of two types of bone structures following an undersized and non-undersized technique.

PURPOSE: The aim of this multi-scale in silico study was to evaluate the influence of resorption cavities on the mechanical properties and load distribution in cortical bone after implant placement with two different drilling protocols. MATERIAL AND METHODS: Two different micro-scale bone structures were assessed: cortical bone models with cavities (test) and without cavities (control) were designed from µCT data. In a macro-scale model, representing a mandibular ridge, oblique load of 150 N was applied on the implant-abutment. Maximum principal stress/strain, and shear stress/strain were calculated in the macro- and micro-scale models. RESULTS: Test presented anisotropic material properties. In tests, significantly greater maximum values of Maximum principal stress/strain were calculated in micro-scale model. These values were located at the implant neck area in the macro-scale model and in the proximity of cavities in the micro-scale model respectively. Greater values of shear stress/strain were found in the test along the mandibular horizontal plane. CONCLUSIONS: Cortical bone with resorption cavities following undersized drilling showed an impaired load distribution compared with bone without cavities. Subsequently, stress/strain distribution suggests that this bone model is more prone to microdamage, thus delaying the healing process.

Long Term Retention of Gingival Sealing around Titanium Implants with CaCl2 Hydrothermal Treatment: A Rodent Study.

We previously reported that CaCl2 hydrothermal-treated (Ca-HT) titanium (Ti) implants induced a tight sealing at the interface between the implant and peri-implant epithelium (PIE) after implantation. However, it is not clear how long this improved epithelium sealing can be maintained. We subsequently investigated whether the positive effect of Ca-HT to promote sealing between the PIE and implant was sustained longer term. Maxillary molars were extracted from rats and replaced with either Ca-HT implants (Ca-HT group), distilled water-HT implants (DW-HT group) or non-treated implants (control group). After 16 weeks, the majority of implants in the Ca-HT group remained at the maxillary with no apical extension of the PIE. Conversely, half the number of control implants was lost following down-growth of the PIE. The effect of Ca-HT on migration and proliferation of rat oral epithelial cells (OECs) was also investigated. In OECs cultured on Ca-HT Ti plates, protein expression in relation to cell migration decreased, and proliferation was higher than other groups. Surface analysis indicated HT enhanced the formation of surface TiO2 layer without altering surface topography. Consequently, Ca-HT of Ti reduced PIE down-growth via tight epithelial attachment to the surface, which may enhance implant capability for a longer time post-implantation.

Intraosseous Temperature Change during Installation of Dental Implants with Two Different Surfaces and Different Drilling Protocols: An In Vivo Study in Sheep.

BACKGROUND: The intraosseous temperature during implant installation has never been evaluated in an in vivo controlled setup. The aims were to investigate the influence of a drilling protocol and implant surface on the intraosseous temperature during implant installation, to evaluate the influence of temperature increase on osseointegration and to calculate the heat distribution in cortical bone. METHODS: Forty Brånemark implants were installed into the metatarsal bone of Finnish Dorset crossbred sheep according to two different drilling protocols (undersized/non-undersized) and two surfaces (moderately rough/turned). The intraosseous temperature was recorded, and Finite Element Model (FEM) was generated to understand the thermal behavior. Non-decalcified histology was carried out after five weeks of healing. The following osseointegration parameters were calculated: Bone-to-implant contact (BIC), Bone Area Fraction Occupancy (BAFO), and Bone Area Fraction Occupancy up to 1.5 mm (BA1.5). A multiple regression model was used to identify the influencing variables on the histomorphometric parameters. RESULTS: The temperature was affected by the drilling protocol, while no influence was demonstrated by the implant surface. BIC was positively influenced by the undersized drilling protocol and rough surface, BAFO was negatively influenced by the temperature rise, and BA1.5 was negatively influenced by the undersized drilling protocol. FEM showed that the temperature at the implant interface might exceed the limit for bone necrosis. CONCLUSION: The intraosseous temperature is greatly increased by an undersized drilling protocol but not from the implant surface. The temperature increase negatively affects the bone healing in the proximity of the implant. The undersized drilling protocol for Brånemark implant systems increases the amount of bone at the interface, but it negatively impacts the bone far from the implant.

Effect of Misfit at Implant-Level Framework and Supporting Bone on Internal Connection Implants: Mechanical and Finite Element Analysis.

PURPOSE: To evaluate the effect of misfit at implant-level fixed partial dentures (ILFPDs) and marginal bone support on the generation of implant cracks. MATERIALS AND METHODS: This in vitro study included a mechanical fatigue test and finite element analysis. A mechanical cycling loading test was performed using 16 experimental models, each consisting of two parallel implants subdivided into four groups based on the misfit and the supporting bone condition. The framework, firmly seated at implants, was dynamically loaded vertically with a force of 1,600/160 N and 15 Hz for 1 × 106 cycles. Optical microscope, scanning electron microscope (SEM), and computed tomography three-dimensional (CT-3D) analyses were performed to detect impairments. Finite element models, representing the setups in the mechanical fatigue test, were used to represent the fatigue life. RESULTS: None of the mechanical components presented distortion or fracture at the macroscopic level during the test. In a microscopy evaluation, the fatigue test revealed scratches visible in the inner part of the conical portion of the implants regardless of the groups. SEM and CT-3D analysis revealed one implant from the misfit/no bone loss group with a microfracture in the inner part of the conical interface. The simulated effective stress levels in the coronal body were higher in the misfit groups compared with the no misfit groups. The misfit groups presented effective stress levels, above 375 MPa, that penetrated the entire wall thickness. The no bone loss group presented an effective stress level above 375 MPa along its axial direction. In the no misfit group, the area presenting effective stress levels above 375 MPa in the conical connection was larger for the bone loss group compared with the no bone loss group. CONCLUSION: This study confirmed that implant fracture is an unlikely adverse event. A clear pattern of effective distribution greater than fatigue limit stresses could be noticed when the misfit was present. The dynamic load simulation demonstrated that the crack is more likely to occur when implants are fully supported by marginal bone compared with a bone loss scenario. Within the limitations of this study, it is speculated that marginal bone loss might follow the appearance of an undetected crack. Further research is needed to develop safe clinical protocols with regard to ILFPD.

Bone-Forming Effect of a Static Magnetic Field in Rabbit Femurs.

This study investigated the level of magnetic energy around implants possessing a static magnetic field (SMF) and assessed the in vivo influence of SMF on bone regeneration. Implants possessing a sintered neodymium magnet internally were placed in a rabbit femur. An implant without SMF was placed as control. After 12 weeks of healing in vivo, the bone samples were subjected to histologic/histomorphometric evaluation. The bone-to-implant contact for the test group and the control group were 32.4 ± 13.6% and 17.1 ± 4.5%, respectively, and the differences were statistically significant (P < .05). The results suggested that the SMF promoted new bone apposition.

Vertical Bone Augmentation Using Ring Technique with Three Different Materials in the Sheep Mandible Bone.

PURPOSE: The purpose of this study was to examine the volumetric alterations and osseointegration properties in the augmented area of the ring technique using different types of bone graft material in sheep mandible bone. MATERIALS AND METHODS: Three different materials (columnar forms, 7-mm diameter, 3-mm height) were stabilized using dental implants with a turned surface in the mandible bone of Finnish Dorset cross-bred sheep: group A, autogenous bone; group B, bovine bone; group C, biphasic bone substitute. Animals were euthanized after 5 weeks (N = 6). Three-dimensional image data by digital oral scanner were taken at the surgery and sacrifice, and the volume alteration of the material was calculated. The bone samples were fixed in formalin and dehydrated in ethanol. Resin-embedded samples were subjected to non-decalcified ground sectioning, and histologic and histomorphometric analysis (bone and material area alteration, bone-to-implant contact [BIC]) were done. RESULTS: In three-dimensional (3D) image analysis, group A showed a statistically higher percentage of remaining materials compared with groups B and C. The histologic observation showed no new bone formations around the implants in all groups, especially at the maxillary site of the implant in the augmented area. In histomorphometric analysis, group A showed a statistically higher percentage of bone area (BA) compared with groups B and C; however, in all groups, bone-to-implant contact (BIC) showed low values, and there were no statistical differences between groups. CONCLUSION: The results of this study suggested that the autogenous bone maintained bone volume around the dental implant using the ring technique, and the impact of surface properties was of some importance; osseointegration with the turned surface in the augmented area showed low BIC values in all groups.

Influence of different drilling preparation on cortical bone: A biomechanical, histological, and micro-CT study on sheep.

OBJECTIVE: The aim of this study was to investigate the extent of cortical bone remodeling between two different drilling protocols by means of histomorphometric, µ-CT, and biomechanical analyses. MATERIAL AND METHODS: A total of 48 implants were inserted into the mandible of six sheep following two drilling protocols: Group A (Test, n = 24), undersized preparation; Group B (Control, n = 24), non-undersized preparation. The animals were euthanatized to obtain 5 and 10 weeks of implantation time. Removal torque (RTQ) was measured on 12 implants of each group and the peri-implant bone was µ-CT scanned. Bone volume density (BV/TV) was calculated in pre-determined cylindrical volumes, up to 1.5 mm from implant surface. Non-decalcified histology was prepared on the remaining 12 implants from each group, where total bone-to-implant contact (totBIC) and newly-formed BIC (newBIC) was measured. Bone Area Fraction Occupancy (BAFO) was determined in pre-determined areas up to 1.5 mm from implant surface. Paired sample t test or Wilcoxon signed-rank test was used to investigate differences between the groups. RESULTS: Group A presented significantly increased RTQ value at 5 weeks, while no difference was observed at 10 weeks. Group B presented increased BV/TV value at 5 weeks. Both groups showed comparable values for totBIC at both time-points. However, Group A presented significantly lower newBIC at 5 weeks. Higher BAFO was observed in Group B at 5 weeks. CONCLUSIONS: Implants inserted into undersized sites has an increased biomechanical performance, but provoked major remodeling of the cortical bone during the early healing period compared to non-undersized preparations. After 10 weeks, no difference was observed.

Controlled release of clarithromycin from PLGA microspheres enhances bone regeneration in rabbit calvaria defects.

This study evaluated the sustained release effect of clarithromycin-loaded in PLGA microspheres in a rabbit calvaria defect model. Four bone defects (ø5.0) were created in the calvaria of New Zealand White rabbits (n = 21, n = 7/time point). The defects were randomly designated to four groups. Group 1: No augmentation (sham), Group 2: beta-tricalcium phosphate (ß-TCP), Group 3: ß-TCP with 0.12 µg clarithromycin, and Group 4: ß-TCP with 6.12 µg PLGA microspheres loaded with 0.12 µg Clarithromycin. After 2, 4, and 12 weeks of healing, bone regeneration was evaluated using micro-computed tomography (µCT) and histology. Clarithromycin release from PLGA microspheres revealed sustained release for around 4 weeks with ∼50% release during the first week. Histologically, new bone formation was evident at 2 and 4 weeks of healing in all groups and bone formation increased as a function of healing time. At 12 weeks, Group 4 showed significantly higher amount of newly formed bone compared to Group 1. The µCT showed that Group 4 expressed significantly higher bone formation compared to Group 1 at all time points. The in vivo findings showed that ß-TCP with clarithromycin-loaded microspheres can enhance bone formation in bone defects. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 201-208, 2018.

In Vivo Evaluation of Dual Acid-Etched and Grit-Blasted/Acid-Etched Implants With Identical Macrogeometry in High-Density Bone.

PURPOSE: Based on the current evidence, the effect of implant macrogeometry has a significant influence on osseointegration. Thus, this study evaluated histomorphometrically and histologically the bone response to acid-etched in comparison to grit-blasted/acid-etched (GB) and machined control (C) surfaced implants possessing identical macrogeometry placed in high-density bone. MATERIALS AND METHODS: Implant surface topography of the 3 different surfaced implants has previously been characterized. The macrogeometry of the implants were conical, and healing chambers were created in the cortical regions. The 3 groups were placed in the external mandibular body of adult male sheep (n = 5). After 6 weeks in vivo, all samples were retrieved for histologic observation and histomorphometry (eg, bone-to-implant contact [BIC] and bone area fraction occupancy [BAFO]). RESULTS: No statistical difference was observed for BIC and for BAFO, although there was a tendency that the mean values for BAFO was higher for the textured surface groups. CONCLUSIONS: It is suggested that the effect of surface topography is minimal in high-density bone and osseointegration seemed to be macrogeometry dependent.

Micro-computed tomography analysis of early stage bone healing using micro-porous titanium mesh for guided bone regeneration: preliminary experiment in a canine model.

The aim of this study was to evaluate the amount of bone formation beneath a defect area after treatment with titanium mesh membranes with different thicknesses and pore sizes alone or in combination with bone graft to induce bone formation during the early stage of healing time. The mandibular premolars were extracted bilaterally from three adult beagle dogs, and 8-mm-diameter bone defects were created on the buccal site of the premolar regions. Hydroxyapatite bone graft substitute was applied in the defect site unilaterally, and other site was left empty. Then, a novel micro-porous mesh (50 µm in pore diameter) or commercially available macro-porous titanium mesh (1700 µm in pore diameter) was placed on the defect and secured with screws. After 4 weeks, the mandibles were harvested, imaged using micro-computed tomography, and prepared for histological and morphometric evaluation. Higher new bone volumes (mm3), percentage of new bone volumes in the total defect volumes (bone ratio: %), and new bone area (mm2) through morphometric evaluation were found on the novel membranes with 50-µm-diameter pores compared to the commercial titanium mesh. Moreover, experiment sites without bone graft were observed with higher new bone volume and bone ratio compared with sites with bone graft. However, bone mineral density of novel mesh was observed to be lower compared with other experimental sites. Under the experimental condition, the result of this study suggests that titanium meshes with 50-µm-diameter pores were effective for guided bone regeneration in the early stage of healing.

Magnesium release from mesoporous carriers on endosseus implants does not influence bone maturation at 6 weeks in rabbit bone.

OBJECTIVES: The release of magnesium ions (Mg2+ ) from titanium surfaces has been shown to boost the initial biological response of peri-implant bone and to increase the biomechanical strength of osseointegration. The objective of the present paper was to investigate if the initial improvement in osseointegration would influence the bone remodeling also during the maturation stage of bone healing. METHODS: Titanium implants were coated with mesoporous titania layers and either loaded with Mg2+ (test group) or left untreated (control group). The implants were inserted in the tibiae of 10 New Zealand White rabbits. Osseointegration was assessed after 6 weeks by means of biomechanical testing (RTQ), non-decalcified histology and histomorphometry (BIC%, BA%, NBA%). The expression of genes involved in the bone formation and remodeling was quantified using qPCR. RESULTS: Mg2+ releasing mesoporous titania coatings showed, on average, higher removal torques and histomorphometrical outcomes (RTQ: 17.2 Ncm vs. 15 Ncm; BIC: 38.8% vs. 32.1%; BA%: 71.6% vs. 64%; NBA% 62.5% vs. 54% for the tests vs the controls); however, the differences were not statistically significant. Three osteogenic markers, osteocalcin (OC), collagen 1 alpha 1 (COL1A1), and alkalin phosphatase (ALPL), were respectively 2-fold, 1.53-fold, and 1.13-fold up-regulated in the control group compared to the test. The expression of COL1A1 was particularly high in both groups, while the biomarkers for remodeling and inflammation showed a low expression in both groups. SIGNIFICANCE: The results suggested that the initial enhancement in osseointegration induced by magnesium release from mesoporous titania coatings has no detrimental effects during bone maturation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2118-2125, 2017.

Tissue Reaction to a Novel Bone Substitute Material Fabricated With Biodegradable Polymer-Calcium Phosphate Nanoparticle Composite.

PURPOSE: The aim of this study was to evaluate the effectiveness of a novel bone substitute material fabricated using a biodegradable polymer-calcium phosphate nanoparticle composite. METHODS: Porous structured poly-L-lactic acid (PLLA) and hydroxyapatite (HA) nanoparticle composite, which was fabricated using solid-liquid phase separation and freeze-drying methods, was grafted into bone defects created in rat calvarium or tibia. Rats were killed 4 weeks after surgery, and histological analyses were performed to evaluate new bone formation. RESULTS: Scanning electron microscopic observation showed the interconnecting pores within the material and the pore diameter was approximately 100 to 300 µm. HA nanoparticles were observed to be embedded into the PLLA beams. In the calvarial implantation model, abundant blood vessels and fibroblastic cells were observed penetrating into pores, and in the tibia model, newly formed bone was present around and within the composite. CONCLUSIONS: The PLLA-HA nanoparticle composite bone substitute developed in this study showed biocompatibility, elasticity, and operability and thus has potential as a novel bone substitute.