Hydroxyapatite Chromatography (HAC).

Tissue engineering has been applied to overcome the obstacles encountered with bone regeneration for the placement of dental implants. The purpose of this study was to determine the bone formation ability of human bone marrow-derived mesenchymal stem cells (BMMSCs) and platelet-rich plasma (PRP) when applied separately or together to the intrabony defect around dental implants with a porous hydroxyapatite (HA) scaffold. Standardized three-wall intrabony defects (4 × 4 × 4 mm) were created at the mesial of each dental implant site in four mongrel dogs. Defects were then grafted with the following materials: HA + BMMSCs (HS group), HA + PRP (HP group), HA + BMMSCs + PRP (HSP group), and HA scaffold alone (HA group). The level of bone formation (bone density) and osseointegration (bone-to-implant contact [BIC]) in bone defects around the implants were evaluated by histological and histometric analysis at 6 and 12 weeks after the placement of implants. HA, HS, HP, and HSP groups generally showed an increase in bone density and BIC between 6 and 12 weeks, except BIC in the HS group. Although no statistically significant differences were found among HA, HS, HP, and HSP groups (p > 0.05), the highest level of bone density and BIC were observed in the HSP group after the 12-week healing period. Furthermore, the level of bone maturation was higher in the HSP group than in the other groups as determined histologically. The findings of this preliminary study suggest that BMMSCs and PRP combined with HA scaffold may provide additional therapeutic effects on bone regeneration and improve osseointegration in bone defects around dental implants.

This study aimed to investigate the effect of hydroxyapatite (HA) augmentation on the maximum lag screw insertion torque (TMax) using extracted human femoral heads. Hemispherical femoral heads extracted from patients who underwent bipolar hip arthroplasty were used. These samples were divided into the HA treatment group (HA group) and the non-HA treatment group (N group). After drilling, HA was inserted into the femoral heads in the HA group. A lag screw was inserted into the femoral head using a dedicated jig in both groups. The bone mineral density of the uninjured contralateral femoral neck (f-BMD), TMax, and the TMax/f-BMD ratio were evaluated. Twenty-seven samples were analyzed in this study: 14 samples in the HA group and 13 samples in the N group. No significant differences were observed in f-BMD and TMax between the two groups (HA: 0.49 ± 0.11 vs. N: 0.48 ± 0.092 g/cm2, p = 0.90; HA: 5.6 ± 1.9 vs. N: 4.3 ± 1.9 N･m, p = 0.78). Considering bone mineral density, the HA group showed a significantly higher TMax/f-BMD ratio than the N group (11.7 ± 3.3 vs. 8.9 ± 3.2 N･m･cm2/g, p = 0.036). Correlation coefficients between f-BMD and TMaxin both groups were moderately strong (r = 0.50 vs. 0.50). Our results suggest that HA augmentation improves lag screw fixation strength in the treatment of osteoporotic intertrochanteric femoral fractures.

BackgroundTo investigate osteointegration at the graft-bone interface and the prevention of osteoarthritis after anterior cruciate ligament (ACL) reconstruction using a silk-collagen scaffold with both ends modified by hydroxyapatite (HA) in a rabbit model.MethodsThe HA/silk-collagen scaffold was fabricated using a degummed, knitted silk scaffold, collagen I matrix, and simulated body fluid (SBF). The HA/silk-collagen scaffold was rolled up to make a graft for replacing the native ACL in the experimental group (HA group), and the silk-collagen scaffold was used in the control (S group). All specimens were harvested at 16 weeks postoperatively to evaluate graft-bone healing and osteoarthritis prevention.ResultsHistological staining revealed the massive formation of more mature bone at the tendon-bone interface, and immunohistochemistry staining revealed more collagen I and osteocalcin deposition in the HA group than in the S group. Higher signals indicating more bone mineral formation were detected in the HA group than in the S group, which was consistent with the results of biomechanical testing. Better osteoarthritis prevention was also observed in the HA group, indicating a more stable knee joint in the HA group than in the S group.ConclusionThe HA/silk-collagen scaffold promotes osteointegration at the tendon-bone interface after ACL reconstruction and has great potential for clinical applications.

To improve the mechanical properties of hydroxyapatite (HA)/waterborne polyurethane (WBPU) composites, the hydroxyl group of HA was modified by urethane reactions: the hydroxyl groups of HA were reacted with aliphatic or cyclic diisocyanate, and then the modified HAs were extended by adding polyol and/or e-caprolactone. Composites were prepared by the prepolymer process method: the modified HA was directly pured into the urethane reaction of isocyanate and polyol. The properties of modified HA/WBPU composites were investigated by thermogravimetric analysis, tensile strength, and water resistance. The results showed that the reactivity of aliphatic diisocyanate to the hydroxy group of HA was faster than that of cyclic one. Comparing to those of pure HA/WBPU composite films, the thermal stability, water resistance, and mechanical properties of the modified composite films increased with a degree of modification of HA. Key Words : Hydroxyapatite, Waterborne polyurethane, Composites

The aim of this study was to evaluate drug release, degree of conversion (DC), and surface properties of resin composites containing chlorhexidine (CHX)-loaded mesoporous (mHAP) and nonporous hydroxyapatite (HAP) nanocarrier. CHX loaded mHAP and HAP, or CHX without nanocarrier was added into the resin composite in 1% and 5% concentrations. After characterization of experimental materials with XRD, EDX, FT-IR, and SEM, the CHX release on the 1st, 7th, 30th, and 120th days were evaluated by UV-vis spectroscopy. DC, surface roughness, and surface hardness of the samples were also evaluated. The data was statistically analyzed. While mHAP groups released significantly higher CHX on the 30th day (p < .05), there was no statistically significant difference between the HAP and mHAP groups on the 120th day (p > .05). DCs of all groups were similar (p > .05). While mHAP and HAP groups containing 5% CHX showed significantly higher roughness than the other groups (p < .05), no statistically significant difference was observed between the other groups (p > .05). The 1% and 5% CHX groups without nanocarrier showed significantly lower surface hardness (p < .05). However, no statistically significant difference was observed between the other groups in terms of surface hardness (p > .05). A controlled CHX release was achieved by mHAP and HAP nanocarriers for 120 days. The nanocarrier addition up to 5% did not negatively affect the DC and the surface hardness which is one of the surface properties of the resin composites. Although the addition of 5% nanocarrier to the resin composite increased the surface roughness, while adding 1% of these nanocarriers did not change.

The Hydroxyapatite-Tapered Stem: Any Added Value?

Purpose:Enucleation of the maxillo-mandibular cysts will create post-surgical bone defects, which may take more than a year for complete bone healing. Bone grafts are common to aid bone regeneration in large defects. The aim was to evaluate the clinical and radiographical healing and bone formation capabilities of polymer of i-PRF and hydroxyapatite in maxilla-mandibular defects compared to hydroxyapatite (HA) alone. The primary objective was to do a clinical assessment of healing at postoperative days 1, 3, and 7; and a radiological evaluation of bone formation postoperatively at the 2nd month and 4th month. A secondary objective was to identify if any, local or systemic side/ill effects of polymer of i-PRF with HA.Material and Methods:After surgical enucleation of 19 maxillo-mandibular cysts/tumors, either HA or HA + i-PRF graft was adapted to the defect. Clinical outcome variables such as Pain (VAS score), edema, and mucosal color were evaluated on postoperative days 01, 03, and 07 while radiological outcome variables such as volume of the defect (cc), and Density of new bone (HU) on Computed Tomography were evaluated at 2nd and 4th month. The results obtained were tabulated and compared with the inferential analysis.Results:Clinical parameters are better in the HA + i-PRF group but the result was non-significant. Radiologically, the mean healing ratios were significantly greater in the HA + i-PRF group (63.5 ± 2.34 at 2nd month, 90.3 ± 7.32 at 4th month) compared to the HA group (57.2 ± 5.21at 2nd month, 80.8 ± 5.33 at 4th month). When comparing the mean density of new bone, there was a statistically significant difference with a mean difference of 95.2 HU more in the HA + i-PRF (623 HU ± 42.9) compared to the HA group (528 HU ± 96.5) in 2nd month.Conclusion:The polymer of i-PRF and HA prepared as the sticky bone yields faster and better bone healing in post-enucleation maxilla-mandibular bony defects as compared to hydroxyapatite alone based on radiological findings till 4 months.

5 - Role of substitution in bioceramics

This is the first work to report on additional Arginin-Glycin-Aspartat (RGD) coating on precoated hydroxyapatite (HA) surfaces regarding new bone formation, implant bone contact, and biocompatibility compared to pure HA coating and uncoated stainless K-wires. There were 39 rabbits in total with 6 animals for the RGD-HA and HA group for the 4 week time period and 9 animals for each of the 3 implant groups for the 12 week observation. A 2.0 K-wire either with RGD-HA or with pure HA coating or uncoated was placed into the intramedullary canal of the tibia. After 4 and 12 weeks, the tibiae were harvested and three different areas of the tibia were assessed for quantitative and qualitative histology for new bone formation, direct implant bone contact, and formation of multinucleated giant cells. Both RGD-HA and pure HA coating showed statistically higher new bone formation and implant bone contact after 12 weeks than the uncoated K-wire. There were no significant differences between the RGD-HA and the pure HA coating in new bone formation and direct implant bone contact after 4 and 12 weeks. The number of multinucleated giant did not differ significantly between the RGD-HA and HA group after both time points. Overall, no significant effects of an additional RGD coating on HA surfaces were detected in this model after 12 weeks.

Background: The current nature of tendon-bone healing after rotator cuff (RC) repair is still the formation of granulation tissue at the tendon-bone interface rather than the formation of fibrocartilage, which is the crucial structure in native tendon insertion and can be observed after knee ligament reconstruction. The interposition of calcium phosphate materials has been found to be able to enhance tendon-bone healing in knee ligament reconstruction. However, whether the interposition of these kinds of materials can enhance tendon-bone healing or even change the current nature of tendon-bone healing after RC repair still needs to be explored. Hypothesis: The interposition of calcium phosphate materials during RC repair would enhance tendon-bone healing or change its current nature of granulation tissue formation into a more favorable process. Study Design: Controlled laboratory study. Methods: A total of 144 male Sprague-Dawley rats underwent unilateral detachment of the supraspinatus tendon, followed by delayed repair after 3 weeks. The animals were allocated into 1 of 3 groups: (1) repair alone, (2) repair with Ca5(PO4)2SiO4 (CPS) bioceramic interposition, or (3) repair with hydroxyapatite (HA) bioceramic interposition at the tendon-bone interface. Animals were sacrificed at 2, 4, or 8 weeks postoperatively, and microcomputed tomography (micro-CT) was used to quantify the new bone formation at the repair site. New fibrocartilage formation and collagen organization at the tendon-bone interface was evaluated by histomorphometric analysis. Biomechanical testing of the supraspinatus tendon-bone complex was performed. Statistical analysis was performed using 1-way analysis of variance. Significance was set at P < .05. Results: The micro-CT analysis demonstrated remarkable osteogenic activity and osteoconductivity to promote new bone formation and ingrowth of CPS and HA bioceramic, with CPS bioceramic showing better results than HA. Histological observations indicated that CPS bioceramic had excellent biocompatibility and biodegradability. At early time points after the RC repair, CPS bioceramic significantly increased the area of fibrocartilage at the tendon-bone interface compared with the control and HA groups. Moreover, CPS and HA bioceramics had significantly improved collagen organization. Biomechanical tests indicated that the CPS and HA groups have greater ultimate load to failure and stiffness than the control group at 4 and 8 weeks, and the CPS specimens exhibited the maximum ultimate load to failure, stiffness, and stress of the healing enthesis. Conclusion: Both CPS and HA bioceramics aid in cell attachment and proliferation and accelerate new bone formation, and CPS bioceramic has a more prominent effect on tendon-to-bone healing. Clinical Relevance: Local application of CPS and HA bioceramic at the tendon-bone interface shows promise in improving healing after rotator cuff tear repair.

05/01777 Thermal variation of the optical absorption ofUO2: Determination of the small polaron self-energy

To compare the clinical outcomes between xenogeneic bone graft materials primarily composed of deproteinized bovine bone mineral (DBBM) and synthetic bone graft materials primarily composed of hydroxyapatite (HA) used in micro crestal flap-alveolar ridge preservation (MCF-ARP) of periodontally compromised molars, so as to provide a reference for their application and promotion. In this retrospective case series study, patients who received treatment between October 2024 and April 2025 were enrolled. All the patients underwent MCF-ARP, using either DBBM or HA. Hard tissue changes and alveolar ridge contour collapse were evaluated and compared between the two groups preoperatively and 6 months postoperatively using cone beam computed tomography (CBCT) and intraoral scanning. Soft tissue healing process after the surgery was also assessed. A total of 14 molars from 14 patients were included. No significant differences were found in hard tissue changes between the two groups 6 months after the surgery (P>0.05). Two weeks and 1 month postoperatively, the vertical collapse of the contour at the ridge center was significantly greater in the HA group compared with the DBBM group [2 weeks: (2.73±1.89) mm vs. (0.00±0.79) mm, P < 0.05; 1 month: (2.74±1.13) mm vs. (0.35±2.34) mm, P < 0.05]. No significant differences were found in other sites at any other follow-up points (P>0.05). In terms of wound healing, the HA group showed a significantly higher percentage of wound area lacking keratinized tissue coverage compared with the DBBM group both 2 weeks and 1 month after the surgery (2 weeks: 47.88%±6.56% vs. 29.43%±14.25%, P < 0.05; 1 month: 25.68%±13.06% vs. 7.19%±7.18%, P < 0.01). Within the limitations of this study, the analysis suggests that there is no statistically significant difference in hard tissue and alveolar ridge contour parameters 6 months after MCF-ARP following extraction of periodontally compromised molars. However, early soft tissue healing is faster when using DBBM. Future randomized controlled trials with histological analysis are warranted for further validation.

The formation of adhesions around the lacerated flexor tendons in zone II was studied in chickens after using an artificial tendon sheath made of hydroxyapatite (HAp). The flexor sheath was excised between the proximal and distal pulleys in zone II to create a window in the fibro-osseous tunnel. After suturing the severed profundus tendon, an HAp sheath was placed around the suture site followed by 3 weeks of immobilization. The results were compared with controls in which no HAp sheaths were used after the operation. Adhesion formation was assessed both biomechanically and histologically. The mobility of the tendons was better in the HAp group at all the periods studied. HAp sheath was not firmly adherent to either the granulation tissue or the surface of the tendon. Histology at 3 as well as 6 weeks in HAp groups revealed epitenon-like structure on the tendon surface including the tenorrhaphy site and a wide space around the tendon after the HAp sheath was removed. The outer margins of this space was lined by a layer of fibrocyte-like cells and collagen fibers thereby resembling new formed tendon sheath. In the cases of control, marked peritendinous adhesions were observed.

A new fluorescent chemosensor 1, which based on hydroxyapatite (HA) nanoparticles covalently functionalized with a difluoroboron dipyrromethene, has been prepared by nucleophilic substitution of the fluorescent dye 3-chloro-4,4-difluoro-8-(4-tolyl)-5-[bis(pyridine2-ylmethyl)amino]-4-bora-3a,4a-diaza-s-indacene (2) with surface-modified HA nanoparticles. The HA particles were prepared by using SiO2 as templates (THA) with 3-(aminopropyl)triethoxysilane (THA-APTES). Substitution of the electron-withdrawing chlorine in 2 by an electron-donating amino group of HA changes the properties of the nanoparticles 1 and the corresponding fluorescent dye 2. Absorption and emission maxima of 1 in ethanol are red-shifted by 75 and 30 nm, respectively, in comparison with those of 2. In contrast to no selectivity of dye 2 for Cd2+ or Zn2+ in EtOH/H2O (95/5 V/V) solutions, the nanofluorescent probe 1 forms 1 : 1 complexes with Cd2+ or Zn2+, producing an instant color change along with large hypsochromic shifts in the absorption and fluorescence spectra by 70 and 35 nm, respectively, and large cation-induced fluorescence amplifications.

Lactic acid is usually formed during strenuous exercise, and a large amount of lactic acid and slow anaerobic glycolysis in muscle lead to limitations of movement ability. Hydroxyapatite (HAp) is an alkaline inorganic material with a good biocompatibility. It slowly degrades in vivo and releases trace amounts of calcium ions, reducing cell damage by reacting with polylactic acid and neutralizing local acid environment. Whether HAp can reduce the concentration of lactic acid in vivo and improve movement ability is not yet clear. Here, after eight days of training, 40 mice were randomly divided into four groups: control, distilled water, sodium bicarbonate and HAp group. After one day of rest, the mice were intravenously injected via the lateral tail veins with 1 ml distilled water, sodium bicarbonate and HAp suspension (2.2 mg/ml), respectively, and subjected to a swimming exhaustive experiment (load 10%). The swimming time of mice in the water, under water and total time were recorded. The exhaustive exercise mice were immediately subject to abdominal cavity anaesthesia. The concentrations of blood, gastrocnemius and myocardial lactic acid as well as serum LDH activity were detected. We demonstrate that HAp can significantly prolong swimming time and improve serum LDH activity, but does not affect lactic acid concentration. In conclusion, intravenous injection of HAp nanoparticles can significantly improve the exhaustive swimming ability of mice mainly because of the elevated blood LDH activity induced by HAp.