Comparative study of the osseous healing process following three different techniques of bone augmentation in the mandible: an experimental study

Authors

M.E. Benlidayi, A. Gaggl, H. Buerger, O.E. Kahraman, L. Sencar, C. Brandtner, M. Kurkcu, S. Polat, F. Borumandi

Abstract

The aim of this study was to evaluate the osseointegration of three different bone grafting techniques. Forty-eight mature New Zealand rabbits were divided randomly into three groups of 16 each. Horizontal augmentation was performed on the corpus of the mandible using three different techniques: free bone graft (FBG), free periosteal bone graft (PBG), pedicled bone flap (BF). The animals were sacrificed at postoperative weeks 1, 3, or 8. Specimens were decalcified for histological examination, and histomorphometric measurements were performed. The histological evaluation demonstrated bony fusion between the grafts and the augmented mandibular bone after 8 weeks in all groups. At week 8, the bone volume was significantly greater in the BF group than in the FBG (P<0.001) and PBG (P=0.001) groups, and also the trabecular thickness was significantly greater than in the FBG (P=0.015) and PBG (P=0.015) groups. Trabecular separation was significantly lower in the BF group than in the FBG group at week 8 (P=0.015). BF demonstrated greater osseous healing capacity compared to FBG and PBG. The preserved vascularization in BF improves the bone quality in mandibular bone augmentations.

Link To Article

http://dx.doi.org/10.1016/j.ijom.2014.07.004

Effects of sodium acetate buffer on chitosan sponge properties and in vivo degradation in a rat intramuscular model

Authors

Ashley Cox Parker, James Keaton Smith, Benjamin Reves, Jessica Amber Jennings, Joel D. Bumgardner and Warren O. Haggard

Abstract

Chitosan sponges were developed for adjunctive local antibiotic delivery to reduce bacteria in wounds. There is a need to increase sponge degradation for rapid clearance from the wound site during initial wound care. This work examined the effect of using 0.25 M sodium acetate buffers, at pH 4.6 or 5.6, to fabricate sponges with an amorphous chitosan polymer structure. Sponges were evaluated for their crystallinity, thermal, spectroscopic, and morphological properties, in addition to in vitro degradation, and cytocompatibility analysis using normal human dermal fibroblasts. In vivo degradation and biocompatibility were also examined after 4 and 10 days in rat intramuscular tissues. Both buffered chitosan sponge variations exhibited decreases in crystallinity and thermal decomposition temperatures, and increases in surface roughness, which resulted in over 40% increases in degradation over 10 days in vitro compared to the neutral sponges. There were no significant differences between sponges during in vivo degradation over 10 days with respect to histomorphometric analysis of the recovered sponges. These results demonstrated that the acetate buffer did change characteristic chitosan sponge material properties, and increasing the in vivo sponge degradation rate will require balancing material characteristics and processing.

Link To Article

http://dx.doi.org/10.1002/jbm.b.33204

A novel one-pot process for near-net-shape fabrication of open-porous resorbable hydroxyapatite/protein composites and in vivo assessment

Authors

Berit Mueller, Dietmar Koch, Rainer Lutz, Karl A. Schlegel, Laura Treccani, Kurosch Rezwan

Abstract

We present a mild one-pot freeze gelation process for fabricating near-net, complex-shaped hydroxyapatite scaffolds and to directly incorporating active proteins during scaffold processing. In particular, the direct protein incorporation enables a simultaneous adjustment and control of scaffold microstructure, porosity, resorbability and enhancement of initial mechanical and handling stability. Two proteins, serum albumin and lysozyme, are selected and their effect on scaffold stability and microstructure investigated by biaxial strength tests, electron microscopy, and mercury intrusion porosimetry. The resulting hydroxyapatite/protein composites feature adjustable porosities from 50 % to 70 % and a mechanical strength ranging from 2 to 6 MPa comparable to that of human spongiosa without any sintering step. Scaffold degradation behaviour and protein release are assessed by in vitro studies. A preliminary in vivo assessment of scaffold biocompatibility and resorption behaviour in adult domestic pigs is discussed. After implantation, composites were resorbed up to 50 % after only 4 weeks and up to 65 % after 8 weeks. In addition, 14 % new bone formation after 4 weeks and 37 % after 8 weeks were detected. All these investigations demonstrate the outstanding suitability of the one-pot-process to create, in a customisable and reliable way, biocompatible scaffolds with sufficient mechanical strength for handling and surgical insertion, and for potential use as biodegradable bone substitutes and versatile platform for local drug delivery.

Link To Article

http://dx.doi.org/10.1016/j.msec.2014.05.017

Osseointegration of dental implants in 3D-printed synthetic onlay grafts customized according to bone metabolic activity in recipient site

Authors

Faleh Tamimi, Jesus Torres, Khadijeh Al-Abedalla, Enrique Lopez-Cabarcos, Mohammad H. Alkhraisat, David C. Bassett, Uwe Gburece, Jake E. Barralet

Abstract

Onlay grafts made of monolithic microporous monetite bioresorbable bioceramics have the capacity to conduct bone augmentation. However, there is heterogeneity in the graft behaviour in vivo that seems to correlate with the host anatomy. In this study, we sought to investigate the metabolic activity of the regenerated bone in monolithic monetite onlays by using positron emission tomography–computed tomography (PET-CT) in rats. This information was used to optimize the design of monetite onlays with different macroporous architecture that were then fabricated using a 3D-printing technique. In vivo, bone augmentation was attempted with these customized onlays in rabbits. PET-CT findings demonstrated that bone metabolism in the calvarial bone showed higher activity in the inferior and lateral areas of the onlays. Histological observations revealed higher bone volume (up to 47%), less heterogeneity and more implant osseointegration (up to 38%) in the augmented bone with the customized monetite onlays. Our results demonstrated for the first time that it is possible to achieve osseointegration of dental implants in bone augmented with 3D-printed synthetic onlays. It was also observed that designing the macropore geometry according to the bone metabolic activity was a key parameter in increasing the volume of bone augmented within monetite onlays.

Link To Article

http://dx.doi.org/10.1016/j.biomaterials.2014.03.050

Anorganic bovine bone (ABB) vs. autologous bone (AB) plus ABB in maxillary sinus grafting. A prospective non-randomized clinical and histomorphometrical trial

Authors

Christian M. Schmitt, Tobias Moest, Rainer Lutz, Friedrich W. Neukam and Karl Andreas Schlegel

Abstract

Objectives This investigation focused on histological characteristics and 5-year implant survival after sinus floor augmentation with anorganic bovine bone (ABB, Bio-Oss®) and ABB plus autologous bone (AB) with a ratio of 1/1.

Material and methods Nineteen consecutive patients with bony atrophy of the posterior edentulous maxilla and a vertical bone height ≤4 mm were prospectively included in this study. In the first surgical stage, the maxillary sinus was non-randomized either augmented with ABB alone (n = 12) or a 1/1 mixture of ABB and AB (n = 7). After a mean healing period of 167 days, biopsies were harvested in the region of the grafted sinus with a trephine burr and implants were placed simultaneously, ABB n = 18 and ABB + AB n = 12. The samples were microradiographically and histomorphometrically analyzed judging the newly formed bone (bone volume, BV), residual bone substitute material volume (BSMV), and intertrabecular volume (soft tissue volume, ITV) in the region of the augmented maxillary sinus. Implant survival was retrospectively evaluated from patient's records.

Results No significant difference in residual bone substitute material (BSMV) in the ABB group (31.21 ± 7.74%) and the group with the mixture of ABB and AB (28.41 ± 8.43%) was histomorphologically determined. Concerning the de novo bone formation, also both groups showed statistically insignificant outcomes; ABB 26.02 ± 5.23% and ABB + AB 27.50 ± 6.31%. In all cases, implants were installed in the augmented sites with sufficient primary stability. After a mean time in function of 5 years and 2 months, implant survival was 93.75% in the ABB and 92.86% in the ABB + AB group with no statistically significant differences.

Conclusion The usage of ABB plus AB to a 1/1 ratio leads to an amount of newly formed bone comparable with the solitary use of ABB after grafting of the maxillary sinus. Considering that ABB is a non-resorbable bone substitute, it can be hypothesized that this leads to stable bone over time and long-term implant success. Importantly, in the sole use of ABB, bone grafting and therefore donor site morbidities can be avoided.

Link To Article

http://dx.doi.org/10.1111/clr.12396

Comparison of stainless steel and titanium alloy orthodontic miniscrew implants: A mechanical and histologic analysis

Authors

Ryan N. Brown, Brent E. Sexton, Tien-Min Gabriel Chu,Thomas R. Katona, Kelton T. Stewart, Hee-Moon Kyung, Sean Shih-Yao Liu

Abstract

Introduction

The detailed mechanical and histologic properties of stainless steel miniscrew implants used for temporary orthodontic anchorage have not been assessed. Thus, the purpose of this study was to compare them with identically sized titanium alloy miniscrew implants.

Methods

Forty-eight stainless steel and 48 titanium alloy miniscrew implants were inserted into the tibias of 12 rabbits. Insertion torque and primary stability were recorded. One hundred grams of tensile force was applied between half of the implants in each group, resulting in 4 subgroups of 24 specimens each. Fluorochrome labeling was administered at weeks 4 and 5. When the rabbits were euthanized at 6 weeks, stability and removal torque were measured in half (ie, 12 specimens) of each of the 4 subgroups. Microdamage burden and bone-to-implant contact ratio were quantified in the other 12 specimens in each subgroup. Mixed model analysis of variance was used for statistical analysis.

Results

All implants were stable at insertion and after 6 weeks. The only significant difference was the higher (9%) insertion torque for stainless steel. No significant differences were found between stainless steel and titanium alloy miniscrew implants in microdamage burden and bone-to-implant contact regardless of loading status.

Conclusions

Stainless steel and titanium alloy miniscrew implants provide the same mechanical stability and similar histologic responses, suggesting that both are suitable for immediate orthodontic clinical loads.

Link To Article

http://dx.doi.org/10.1016/j.ajodo.2013.12.022