How does the amount of surgical insult affect bone around moving teeth?

Authors

Matthew D. McBride, Phillip M. Campbell, Lynne A. Opperman, Paul C. Dechow, Peter H. Buschang

Abstract

Introduction

The purpose of this study was to determine how the amount of surgical insult affects the quantity and maturity of dentoalveolar bone around teeth that have been orthodontically moved.

Methods

A split-mouth design with 8 foxhound dogs was used to evaluate bone surrounding maxillary second premolars that were protracted for 15 days and retained for 7 weeks. The maxillary first premolars were extracted, and the interseptal bone was removed to within 1 mm of the second premolars; on the insult (lesser surgical insult) side, buccal and lingual vertical grooves were made in the extraction socket to undermine the mesial root of the second premolar; the insult+ (greater surgical insult) side was flapped and had modified corticotomies extending to, but not through, the lingual cortex 1 mm distal to the distal root, and 3 to 5 mm apical to both roots. Microcomputed tomography analyses were used to evaluate the material density, bone volume fraction, and trabecular characteristics of surrounding bone. Hematoxylin and eosin sections were used to determine osteoclast numbers, bone surface areas, and bone volumes.

Results

After 7 weeks of consolidation, there was significantly (P <0.05) less bone on the insult+ side; it was less dense and less mature than the bone on the insult side. Relative to the control bone, bone on the insult+ side was significantly less dense but showed no differences in bone volume. Preliminary histologic evaluations indicated increased numbers of osteoclasts and greater bone surface areas on the insult+ side than the insult side, but no differences in bone volume.

Conclusions

Increased surgical insults produce less dense and less mature bone but have no effect on bone volume at 9 weeks after surgery.

Link To Article

http://dx.doi.org/10.1016/j.ajodo.2013.10.020

Entangled Titanium Fibre Balls Combined with Nano Strontium Hydroxyapatite in Repairing Bone Defects

Authors

Ping Liu, Nan Wang, Yongqiang Hao, Qinghua Zhao, Yongmin Qiao, Hui Li, Jipeng Li

Abstract

Objective: To investigate the effect of entangled titanium fibre balls (ETFBs) combined with nano strontium hydroxy-apatite (nano-Sr-HAP) on the repair of bone defects in vivo.

Materials and Methods: Twenty-four 6-month-old, specific pathogen-free, male Sprague-Dawley rats were used. Drill defects were created in bilateral femoral condyles. ETFBs combined with nano-Sr-HAP were selected randomly from 72 samples and implanted into the femoral bone defects of left legs, which served as the experimental group, while ETFBs without nano-Sr-HAP were implanted into right legs for comparison. The bone defects on both sides were X-rayed. The anteroposterior positions and histological procedures and evaluations of each sample were performed at 1, 2, 4 and 8 weeks post-surgery.

Results: Histological results showed that the ETBs allowed new bone to grow within their structure. Additionally, an increase in new bone was seen on the nano-Sr-HAP side compared to the control side. The results of histomorphometric analysis confirmed that the new bone formation on the left side gradually increased with time. There was a statistical increase in new bone at 2, 4 and 8 weeks, and the differences between the two sides were statistically significant at weeks 4 and 8 (p < 0.05 for all comparisons). The results showed that ETFBs possess a unique 3-dimensional interconnective porous structure and have excellent biocompatibility, cell affinity and osteoconductivity, which makes them useful as scaffold materials for repairing bone defects. On the other hand, nano-Sr-HAP improved the bone defect-repairing capacity of the ETFBs, which showed osteoinductive properties.

Link To Article

http://www.karger.com/Article/PDF/359951

Antagonizing the αvβ3 Integrin Inhibits Angiogenesis and Impairs Woven but Not Lamellar Bone Formation Induced by Mechanical Loading

Authors

Ryan E. Tomlinson, Anne H. Schmieder, James D. Quirk, Gregory M. Lanza, and Matthew J. Silva

Abstract

Angiogenesis and osteogenesis are critically linked, though the role of angiogenesis is not well understood in osteogenic mechanical loading. In this study, either damaging or non-damaging cyclic axial compression was used to generate woven bone formation (WBF) or lamellar bone formation (LBF), respectively, at the mid-diaphysis of the adult rat forelimb. αvβ3 integrin targeted nanoparticles or vehicle was injected intravenously following mechanical loading. β3 integrin subunit expression on vasculature was maximal 7 days after damaging mechanical loading, but was still robustly expressed 14 days after loading. Accordingly, targeted nanoparticle delivery in WBF loaded limbs was increased compared to non-loaded limbs. Vascularity was dramatically increased after WBF loading (+700% on day 14) and modestly increased after LBF loading (+50% on day 14). This increase in vascularity was inhibited by nanoparticle treatment in both WBF and LBF loaded limbs at days 7 and 14 after loading. Decreased vascularity led to diminished woven, but not lamellar, bone formation. Decreased woven bone formation resulted in impaired structural properties of the skeletal repair, particularly in post-yield behavior. These results demonstrate that αvβ3 integrin mediated angiogenesis is critical for recovering fracture resistance following bone injury, but is not required for bone modeling after modest mechanical strain.

Link To Article

http://dx.doi.org/10.1002/jbmr.2223

The effects of bazedoxifene in the ovariectomized aged cynomolgus monkey

Authors

Susan Y. Smith, Jacquelin Jolette, Luc Chouinard, Barry S. Komm

Abstract

Bazedoxifene (BZA) is a novel selective estrogen receptor modulator in clinical development for the prevention and treatment of postmenopausal osteoporosis. This preclinical study evaluated the efficacy and safety of BZA in preventing ovariectomy (OVX)-induced bone loss in aged cynomolgus monkeys. Animals (18 per group) underwent OVX and were administered BZA (0.2, 0.5, 1, 5, or 25 mg/kg/day) or vehicle, or were sham-operated and administered vehicle, by daily oral gavage for 18 months. Biochemical markers of bone turnover were assessed at 6, 12, and 18 months, along with bone densitometry using dual energy X-ray absorptiometry and peripheral quantitative computed tomography. Animals were killed after 18 months. Uterine and pituitary weights were determined, and histomorphometric and biomechanical measurements were performed. OVX vehicle controls showed increases in bone turnover associated with cancellous and cortical bone osteopenia (in vivo), and slight decreases (not statistically significant) in biomechanical strength parameters at the lumbar spine and femoral neck. BZA partially preserved cortical and cancellous bone mass by preventing the OVX-induced increases in bone turnover. Although the response was often similar among BZA-treated groups, the strongest efficacy was generally seen at 25 mg/kg/day. Treatment with BZA did not adversely affect measures of bone strength and was well tolerated; there was no evidence of uterotrophic activity, mammary tissue was unaffected, and there were no adverse effects on plasma lipids. Treatment of ovariectomized animals with BZA partially prevented changes in bone remodeling that correlated with increases in bone mineral density, while maintaining bone strength and a favorable safety profile.

Link To Article

http://dx.doi.org/10.1007/s00774-014-0580-z

Hip osteoarthritis and osteoporosis: clinical and histomorphometric considerations

Authors

Umberto Tarantino, Monica Celi, Cecilia Rao, Maurizio Feola, Irene Cerocchi, Elena Gasbarra, Amedeo Ferlosio and Augusto Orlandi

Abstract

Although an inverse relationship between osteoarthritis (OA) and osteoporosis (OP) has been shown by some studies, other reports supported their co-existence. To clarify this relationship we analyzed the interplay between clinical and histomorphometric features. Bone mineral density (BMD) and histomorphometric structure were assessed in 80 patients of four different age-matched groups undergoing hip arthroplasty for severe OA or OP-related femoral fracture. Harris Hip Score was also performed. Surgical double osteotomy of the femoral head was performed and microscopic bone slice samples analysis was performed by using a BioQuant Osteo software. Bone volume fraction (BV/TV) was lower (p<0.01) in subjects with femoral neck fracture (20.77±4.34%) than in subjects with non-osteopenic OA (36.49±7.73%) or osteopenic OA (32.93±6.83%), whereas no difference was detected between subjects with femoral neck fractures and those with combined OA and OP (20.71±5.23%). Worse Harris Hip Score was found in those patients with the lowest BMD and BV/TV values. Our data support recent evidences indicating the possibility of impaired bone volume fraction in OA patients, with a high risk of developing OP, likely for their decreased mobility. Further studies are needed in order to investigate biomolecular pathway and/or growth factors involved in bone volume impairment in OA patients.

Link To Article

http://downloads.hindawi.com/journals/ije/aip/372021.pdf

Kruppel-like factor 4 attenuates osteoblast formation, function, and cross talk with osteoclasts

Authors

Jung Ha Kim, Kabsun Kim, Bang Ung Youn, Jongwon Lee, Inyoung Kim, Hong-In Shin, Haruhiko Akiyama, Yongwon Choi, and Nacksung Kim

Abstract

Osteoblasts not only control bone formation but also support osteoclast differentiation. Here we show the involvement of Kruppel-like factor 4 (KLF4) in the differentiation of osteoclasts and osteoblasts. KLF4 was down-regulated by 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) in osteoblasts. Overexpression of KLF4 in osteoblasts attenuated 1,25(OH)2D3-induced osteoclast differentiation in co-culture of mouse bone marrow cells and osteoblasts through the down-regulation of receptor activator of nuclear factor κB ligand (RANKL) expression. Direct binding of KLF4 to the RANKL promoter repressed 1,25(OH)2D3-induced RANKL expression by preventing vitamin D receptor from binding to the RANKL promoter region. In contrast, ectopic overexpression of KLF4 in osteoblasts attenuated osteoblast differentiation and mineralization. KLF4 interacted directly with Runx2 and inhibited the expression of its target genes. Moreover, mice with conditional knockout of KLF4 in osteoblasts showed markedly increased bone mass caused by enhanced bone formation despite increased osteoclast activity. Thus, our data suggest that KLF4 controls bone homeostasis by negatively regulating both osteoclast and osteoblast differentiation.

Link To Article

http://dx.doi.org/10.1083/jcb.201308102