En Luo

The effect of strontium-substituted hydroxyapatite coating on implant fixation in ovariectomized rats

This study was designed to investigate the effects of strontium-substituted hydroxyapatite coatings with 10 mol% Ca(2+) replaced by Sr(2+) (10% SrHA) on implant fixation in ovariectomized (OVX) rats. Coatings of HA and 10% SrHA were prepared on the surface of titanium implant using sol-gel dip methods, and then characterized by Scanning Electron Microscope, Atomic Force Microscope, X-ray diffraction, X-ray Photoemission Spectroscopy, and an automatic scratch tester. Twelve weeks after bilateral ovariectomy, twenty OVX rats accepted implant insertion in the proximal tibiae, half with HA-coated implants and the other half with 10% SrHA coated implants. After 12-week healing period, 10% SrHA coated implants revealed improved osseointegration compared to HA, with the bone area ratio and bone-to-implant contact increased by 70.9% and 49.9% in histomorphometry, the bone volume ratio and percent osseointegration by 73.7% and 45.2% in micro-CT evaluation, and the maximal push-out force and ultimate shear strength by 107.2% and 132.9% in push out test. These results demonstrated that 10% SrHA coatings could enhance implant osseointegration in OVX rats, and suggested the feasibility of using SrHA coatings to improve implant fixation in osteoporotic bone.

Effect of combined local treatment with zoledronic acid and basic fibroblast growth factor on implant fixation in ovariectomized rats

Osteoporosis is a skeletal disorder characterized by low bone mass and deterioration of bone microarchitecture resulting in bone fragility, which impairs fixation of the implants. Zoledronic acid (ZOL) is a potential inhibitor of osteoclast-mediated bone resorption and basic fibroblast growth factor (bFGF) is a growth factor that stimulates osteoblast-mediated bone formation, and these drugs could enhance fixation of implants under osteoporotic conditions. In this study, 40 ovariectomized (OVX) rats were randomly divided into 4 groups (n=10 for each group) and underwent bilateral tibiae implantation using hydroxyapatite (HA)-coated titanium implant: Control group (distilled water immersing before implantation), ZOL group (1 mg/ml of ZOL immersing), bFGF group (20 microg/ml of bFGF immersing), and ZOL+bFGF group (1 mg/ml of ZOL and 20 microg/ml of bFGF immersing). At 3 months after implantation, all animal were sacrificed and the tibiae were harvested for histology, micro-CT examinations and biomechanical testing. Bone area and contact, determined by histomorphometric analysis, were 2.7-fold and 1.8-fold in the ZOL-treated implants, 1.9-fold and 1.8-fold in the bFGF-treated implants, 3.6-fold and 2.3-fold in the both-treated implants compared with controls (p<0.01). Such significant effects were further confirmed by microstructure parameters, the bone volume ratio and the percentage osteointegration were significantly increased by ZOL treatment (3.0-fold and 1.8-fold), bFGF treatment (1.2-fold and 1.9-fold) and ZOL+bFGF treatment (3.3-fold and 2.7-fold) (p<0.001). In addition, push-out test showed that the maximum force and the corresponding interfacial shear strength of the implants treated by ZOL, bFGF and ZOL+bFGF was 8.4-fold and 8.6-fold, 3.8-fold and 3.7-fold, 10.8-fold and 10.7-fold of the control levels, respectively (p<0.05). The combined treatment was better than either treatment alone for force, but was not different from ZOL alone for interfacial strength. The significant correlation between biomechanical and micro-CT parameters demonstrates the role of microstructure assessments in predicting mechanical fixation of implants (p<0.01). Our study suggests that locally applied ZOL or bFGF may improve implant fixation in the ovariectomized rats, and that combined treatment has more beneficial effects on osseointegration, peri-implant bone formation and maximum force than either intervention alone.

Systemic treatment with strontium ranelate promotes tibial fracture healing in ovariectomized rats

SummarySystemic treatment with strontium ranelate (SR) was performed on ovariectomized (OVX) rats with fractured tibiae. Callus quality was assessed by radiographic, histological, micro-computerized tomography, and biomechanical examinations at 4 and 8xa0weeks after fracture. Results revealed that systemic applied SR promoted osteoporotic fracture healing.IntroductionSeveral studies have demonstrated the dual effect of SR on osteoporotic and undisturbed bone. However, reports of their effect on osteoporotic fracture healing are limited. This study was designed to investigate the effects of SR on bone regeneration in OVX rats with fractured tibiae.MethodsThree months after being OVX, female Sprague–Dawley rats accepted bilateral osteotomy on proximal tibiae fixed with intramedullary wires and were divided into two groups: OVX and OVXu2009+u2009SR (625xa0mg/kg/day). Callus quality was evaluated at 4 and 8xa0weeks postfracture.ResultsCompared with OVX group, SR treatment significantly increased bone formation, BMD, biomechanical strength, and improved microstructural properties of the callus. The ultimate load was increased by 211.0% and 61.4% (pu2009<u20090.01), and the total bone volume of callus by 74.8% and 79.3% (pu2009<u20090.01) at 4 and 8xa0weeks postfracture, respectively. SR treatment also promoted healing progress with increased osteogenesis at 4xa0weeks; more mature and tightly arranged woven or lamellar bone at 8xa0weeks across the fracture gap in histological analysis.ConclusionThis study suggests that systemic treatment with strontium ranelate could promote tibial fracture healing in OVX rats.

Strontium ranelate treatment enhances hydroxyapatite-coated titanium screws fixation in osteoporotic rats

Increased bone turnover with excessive bone resorption and decreased bone formation is known to impair implant fixation. Strontium ranelate is well known as an effective antiosteoporotic agent by its dual effect of antiresorbing and bone‐forming activity. This study was designed to evaluate the effect of systemic strontium ranelate (SR) treatment on fixation of hydroxyapatite (HA)‐coated titanium screws in ovariectomized (OVX) rats. Twelve weeks after being OVX (nu2009=u200930) or sham (nu2009=u200910) operated, 40 female Sprague–Dawley rats received unilateral implants in the proximal tibiae. The OVX rats were randomly divided into the following groups: OVX, OVXu2009+u2009SRL (“L” refers to low SR dose of 500 mg/kg/day), OVXu2009+u2009SRH (“H” refers to high SR dose of 1000 mg/kg/day).Twelve weeks after treatment, bone blocks with implants were evaluated with micro‐CT and biomechanical push‐out tests. Compared to OVX animals, SR treatment increased the bone volume ratio by 51.5% and 1.1‐fold, the percentage osteointegration by 1.0‐fold and 1.9‐fold in micro‐CT evaluation, and the maximal force by 1.9‐fold and 3.3‐fold in biomechanical push‐out test, for the low and high dose of SR, respectively. Significant correlation between micro‐CT and biomechanical properties demonstrated that trabecular parameters played an important role in predicting the biomechanical properties of implant fixation. Our findings suggest that SR treatment can dose‐dependently improve HA‐coated screw fixation in OVX rats and facilitate the stability of the implant in the osteoporotic bone.

The effects of combined human parathyroid hormone (1-34) and zoledronic acid treatment on fracture healing in osteoporotic rats.

SummaryOvariectomized (OVX) rats with tibial fracture received vehicle, ZA, PTH, or ZA plus PTH treatment for 4 and 8xa0weeks. Bone metabolism, callus formation, and the mass of undisturbed bone tissue were evaluated by serum analysis, histology, immunohistochemistry, radiography, micro-computerized tomography, and biomechanical test.IntroductionPrevious studies have demonstrated the effect of ZA or PTH on osteoporotic fracture healing. However, reports about effects of ZA plus PTH on callus formation of osteoporotic fracture were limited. This study was designed to investigate the impact of combined treatment with ZA and PTH on fracture healing in OVX rats.MethodsTwelve weeks after bilateral ovariectomy, all rats underwent unilateral transverse osteotomy on tibiae. Animals then randomly received vehicle, ZA (1.5xa0μg/kg weekly), PTH (60xa0μg/kg, three times a week), or ZA plus PTH until death at 4 and 8xa0weeks. The blood and bilateral tibiae of rats were harvested for evaluation.ResultsAll treatments increased callus formation and strength other than the control; ZA + PTH showed the strongest effects on percent bone volume (BV/TV), trabecular thickness, total fluorescence-marked callus area, and biomechanical strength. Additionally, inhibited RANKL and enhanced osteoprotegerin expression were observed in the ZA + PTH group. But no difference in bone mineral density and BV/TV of the contralateral tibiae was observed between treated groups.ConclusionFindings in this study suggested an additive effect of ZA and PTH on fracture healing in OVX rats, and this additive effect was specific to callus formation, not to undisturbed bone tissue.

Changes in quality of life after orthognathic surgery: a comparison based on the involvement of the occlusion

OBJECTIVESnThe aims of this study were to investigate the impact of dentofacial deformities on quality of life in Chinese patients and to make a comparison between facial deformities that do and do not involve the occlusion.nnnSTUDY DESIGNnConsecutive patients with dentofacial deformities requiring surgical correction were divided into 2 groups. Group A represented those who had undergone presurgical orthodontic treatment, and group B represented patients with square faces or prominent zygoma. All subjects were assessed by the 36-item Short-Form Health Survey (SF-36) and the 22-item Orthognathic Quality of Life Questionnaire (OQLQ-22) during 2 time periods: preoperatively and 6-8 months postoperatively.nnnRESULTSnThe SF-36 revealed that there was significant difference in role physical and bodily pain (P < .05) preoperatively between the 2 groups, whereas postoperatively the difference was not significant. Preoperatively, there was significant difference in oral function and facial esthetics components of OQLQ (P < .001), whereas postoperatively only the oral function domain showed significant difference.nnnCONCLUSIONSnOrthognathic surgery had a positive impact on patients quality of life regardless of the type of deformity. OQLQ showed better discerning ability and was able to point out the subtle differences between the 2 groups.

Schwann-like mesenchymal stem cells within vein graft facilitate facial nerve regeneration and remyelination.

To compare the ability of bone marrow mesenchymal stem cells (MSCs) and transdifferentiated Schwann-like MSCs (tMSCs) in promoting transected facial nerve branches repair in a rabbit model of injury, rabbit tMSCs were induced from bone marrow MSCs, and Schwann cells markers were assessed by Western blot analysis. The left facial nerve buccal branch was transected to form a 1-cm gap in 54 rabbits, and the gaps were immediately bridged using autologous vein grafts. Animals were then randomly assigned to three groups: vein graft (VG); VG+MSCs, and VG+tMSCs (n=18/group). Saline, autologous MSCs, and Schwann-like tMSCs were injected into vein conduits. Rabbits were sacrificed at week 4, 8, and 16 post-surgery. Facial nerves regeneration and myelination were analyzed by functional, immunohistochemical, and morphological tests. In addition, myelin protein genes expression, including peripheral myelin protein 22 (PMP22), myelin protein zero (P0), and myelin basic protein (MBP), in transplanted cells in vivo were assayed using real time quantitative-reverse transcription-polymerase chain reaction (RT-PCR). Rabbit tMSCs expressed Schwann cells markers, and results demonstrated better facial nerve functional recovery in the VG+tMSCs group, with earlier horseradish peroxidase (HRP) positive neurons appearance and a greater number of MBP positive myelinated axons since 4weeks after transplantation. Moreover, RT-PCR analysis showed transplanted tMSCs in vivo expressed higher myelin proteins at mRNA level than those of MSCs during the first 8weeks of neural regeneration. This study suggests that rabbit transdifferentiated Schwann-like MSCs within autogenous vein graft accelerate transected axons regeneration and achieve better remyelinization.

Correction of square jaw with low angles using mandibular “V-line” ostectomy combined with outer cortex ostectomy

OBJECTIVEnThe objective of this study was to evaluate the feasibility and effectiveness of correction for square jaw with low angle using mandibular V-line ostectomy combined with outer cortex ostectomy.nnnSTUDY DESIGNnFrom July 2005 to November 2007, 31 patients who had square faces with low angles were treated with mandibular V-line ostectomy combined with mandibular outer cortex ostectomy. All the patients had standard frontal and lateral cephalometric radiographs, panoramic radiographs, and were photographed preoperatively and postoperatively to assess their face contour. The alteration of mandibular angle and width of lower face was observed for 6 to 24 months postoperatively.nnnRESULTSnPostoperative appearance of all 31 cases showed that the width of lower face was reduced expectedly; the gonial angle and the mandibular plane angle were increased effectively. The final aesthetic outcomes were quite satisfactory in all cases for both the surgeons and the patients.nnnCONCLUSIONnA slender oval facial outline as the fashionable aesthetics could be achieved by using mandibular V-line ostectomy combined with mandibular outer cortex ostectomy. It might be a feasible and a reasonable surgical procedure for correction of square jaw with low angle.

Reduction malarplasty using an L-shaped osteotomy through intraoral and sideburns incisions.

The slender, oval-shaped face is considered to be attractive in East Asia. To obtain the ideal contour of the midface, reduction malarplasty has been popularized in oriental countries in recent years. This report describes a surgical technique for reduction of the zygomatic body and arch. After labiobuccal vestibular incisions are made, the anterior zygomatic body and lateral orbital rim are exposed by subperiosteal dissection. Thereafter, an L-shaped osteotomy is performed. Two parallel horizontal osteotomies are made in the anterior part of the zygomatic body, and the middle bone segment is removed. The zygomatic arch root is fractured through a small sideburn incision just anterior to the articular tubercle. Finally, the freed zygomatic complex is medially repositioned and fixed with one or two bicortex screws. Operations on 32 patients demonstrated that this technique may be a sound method for malar complex reduction, with the advantages of simple manipulation, stable fixation, and less risk of a drooping face.

Basic fibroblast growth factor suspended in Matrigel improves titanium implant fixation in ovariectomized rats

Basic fibroblast growth factor (bFGF) has high potential for tissue regeneration; however, its in vivo effects are unpredictable due to the short-term survival. This study sought to evaluate the effects of bFGF suspended in Matrigel on the implant fixation in ovariectomized (OVX) rats. In vitro, the release kinetics of bFGF was tested using an immuno-ligand-assay. In vivo, eighty titanium implants were randomly divided into 4 groups and inserted in the tibiae of forty OVX rats: no treatment group, bFGF alone group, Matrigel alone group and bFGF+Matrigel group. At 3 months after implantation, tibiae were examined by histology, micro-CT and push-out test. We found that Matrigel could prolong the life span of bFGF in vitro with a sustained release during the 21 days. In vivo, bFGF or Matrigel alone had little effect on the fixation of implant in OVX rats, but bFGF suspended in Matrigel induced nearly 2-fold of peri-implant new bone formation and 4-fold of implant mechanical stability when compared to other 3 groups. The results of this study suggest that Matrigel could be used as a carrier of bFGF and prolonged its release around implant, which may improve implant fixation, especially in site of post-menopausal osteoporosis.