Biomechanical and histomorphometric evaluation of biodegradable mini-implants for orthodontic anchorage in the mandible of beagle dogs

AUTHORS

Shuo Wang, Zuodong Zhao, Qingtao Zhang, Chang Liu

ABSTRACT

Objective

To evaluate the effectiveness of a mini-implant composed of unsintered hydroxyapatite, poly (L-lactic acid) and poly(lactic-co-glycolic acid) (u-HA/PLLA/PLGA) composites as an anchorage device under consistent orthodontic force (OF) loading in vivo.

Methods

An mandible model in beagle dogs was introduced. 144 mini-implants were implanted in both sides of the mandibles. The mini-implants in the experimental group (left side) were loaded at the magnitude of 200 g to simulate the OF. At 2, 4 and 6 months after implantation, tissue specimens were taken from the implanted sites and biomechanical, histological and histomorphometrical analysis were performed.

Results

Mini-implants in the group with the highest PLLA ratio showed a 27% non-fracture rate after 4 months and 20.83% after 6 months in beagle dogs, and the non-fractured mini-implants could maintain the tensile force of 200 g, while mini-implants in the other two groups were all fractured. Histomorphological analysis showed that there was no significant relationship between Bone Volume over Total Volume (BV/TV) and the implantation time among the most of the groups. The level of Bone-Implant Contact ratio (BIC) in Medium and Low ratio group were decreased gradually from 2 to 6 months.

Conclusions

This study showed the biodegradable mini-implant could work as an alternative to the titanium alloy mini-implant by adjusting the proportion of its ingredients.

Clinical relevance

Degradable mini-implants for orthodontic anchorage lie in their potential to revolutionize orthodontic treatments by offering a biodegradable alternative that minimizes the need for secondary surgeries for removal, thereby enhancing patient comfort and reducing overall treatment time.

Sinus floor augmentation using a composite graft of bone morphogenic protein-2 and allogenic cancellous bone (Puros): case report

AUTHORS

Lee M Whitesides, Alaaaldin Radwan, Mohamed Sharawy

ABSTRACT

Reconstruction of the atrophic maxilla is a difficult task. The gold standard for such reconstruction is autogenous bone. Presently, many excellent products are available to the dental surgeon to facilitate alveolar reconstruction in the absence of autogenous bone. This study describes the use of bone morphogenic protein in combination with allogenic bone substitute (Puros) to reconstruct the maxilla in preparation for dental implant placement.

Calycosin alleviates titanium particle-induced osteolysis by modulating macrophage polarization and subsequent osteogenic differentiation

AUTHORS

Hui Jiang, Yang Wang, Zhao Tang, Xianjiang Peng, Chan Li, Yangjie Dang, Rui Ma

ABSTRACT

Periprosthetic osteolysis (PPO) caused by wear particles is one of the leading causes of implant failure after arthroplasty. Macrophage polarization imbalance and subsequent osteogenic inhibition play a crucial role in PPO. Calycosin (CA) is a compound with anti-inflammatory and osteoprotective properties. This study aimed to evaluate the effects of CA on titanium (Ti) particle-induced osteolysis, Ti particle-induced macrophage polarization and subsequent osteogenic deficits, and explore the associated signalling pathways in a Ti particle-stimulated calvarial osteolysis mouse model using micro-CT, ELISA, qRT-PCR, immunofluorescence and western blot techniques. The results showed that CA alleviated inflammation, osteogenic inhibition and osteolysis in the Ti particle-induced calvarial osteolysis mouse model in vivo. In vitro experiments showed that CA suppressed Ti-induced M1 macrophage polarization, promoted M2 macrophage polarization and ultimately enhanced osteogenic differentiation of MC3T3-E1 cells. In addition, CA alleviated osteogenic deficits by regulating macrophage polarization homeostasis via the NF-κB signalling pathway both in vivo and in vitro. All these findings suggest that CA may prove to be an effective therapeutic agent for wear particle-induced osteolysis.

Effect of Press-Fit Size on Insertion Mechanics and Cartilage Viability in Human and Ovine Osteochondral Grafts

AUTHORS

R.P. Suderman, M.B. Hurtig, M.D. Grynpas, P.R.T. Kuzyk, and A. Changoor

ABSTRACT

Objective

The osteochondral allograft procedure uses grafts constructed larger than the recipient site to stabilize the graft, in what is known as the press-fit technique. This research aims to characterize the relationships between press-fit size, insertion forces, and cell viability in ovine and human osteochondral tissue.

Design

Human (4 donors) and ovine (5 animals) articular joints were used to harvest osteochondral grafts (4.55 mm diameter, N = 33 Human, N = 35 Ovine) and create recipient sites with grafts constructed to achieve varying degrees of press fit (0.025-0.240 mm). Donor grafts were inserted into recipient sites while insertion forces were measured followed by quantification of chondrocyte viability and histological staining to evaluate the extracellular matrix.

Results

Both human and ovine tissues exhibited similar mechanical and cellular responses to changes in press-fit. Insertion forces (Human: 3-169 MPa, Ovine: 36-314 MPa) and cell viability (Human: 16%-89% live, Ovine: 2%-76% live) were correlated to press-fit size for both human (force: r = 0.539, viability: r = −0.729) and ovine (force: r = 0.655, viability: r = −0.714) tissues. In both species, a press-fit above 0.14 mm resulted in reduced cell viability below a level acceptable for transplantation, increased insertion forces, and reduced linear correlation to press-fit size compared to samples with a press-fit below 0.14 mm.

Conclusions

Increasing press-fit size required increased insertion forces and resulted in reduced cell viability. Ovine and human osteochondral tissues responded similarly to impact insertion and varying press-fit size, providing evidence for the use of the ovine model in allograft-related research.

A novel micro-CT analysis for evaluating the regenerative potential of bone augmentation xenografts in rabbit calvarias

AUTHORS

Ilan Beitlitum, Fatma Rayyan, Ariel Pokhojaev, Haim Tal & Rachel Sarig

ABSTRACT

Guided Bone Regeneration is a common procedure, yet, as new grafting materials are being introduced into the market, a reliable evaluation method is required. Critical size defect in animal models provides an accurate simulation, followed by histological sections to evaluate the new bone formation. However, histology is destructive, two-dimensional and technique-sensitive. In this study we developed a novel volumetric Micro-CT analysis to quantify new bone formation characteristics. Eight adult female New Zealand white rabbits were subjected to calvarial critical-size defects. Four 8 mm in diameter circular defects were preformed in each animal, to allow random allocation of four treatment modalities. All calvarias were scanned using Micro-CT. Each defect was segmented into four equal parts: pristine bone, outer, middle, and inner. Amira software (v. 6.3, www.fei.com) was used to calculate the new bone volume in each region and compare it to that of the pristine bone. All grafting materials demonstrated that new bone formation decreased as it moved inward. Only the inner region differed across grafting materials (p = 0.001). The new Micro-CT analysis allowed us to divide each defect into 3D regions providing better understanding of the bone formation process. Amongst the various advantages of the Micro-CT, it enables us to quantify the graft materials and the newly formed bone independently, and to describe the defect morphology in 3D (bi- vs. uni-cortical defects). Providing an insight into the inner region of the defect can better predict the regenerative potential of the bone augmentation graft material. Therefore, the suggested Micro-CT analysis is beneficial for further developing of clinical approaches.

Near-infrared light responsive gold nanoparticles coating endows polyetheretherketone with enhanced osseointegration and antibacterial properties

AUTHORS

Xinxin Zhan, Jianglong Yan, Dong Xiang, Hao Tang, Lulu Cao, Yufeng Zheng, Hong Lin, Dandan Xia

ABSTRACT

Polyetheretherketone (PEEK) is considered as a promising dental implant material owing to its excellent physicochemical and mechanical properties. However, its wide range of applications is limited by its biologically inert nature. In this study, a near-infrared (NIR) light responsive bioactive coating with gold nanoparticles (AuNPs) and metronidazole adhered to the PEEK surface via dopamine polymerization. Compared to pure PEEK, the hydrophilicity of the treated PEEK surface was significantly improved. In addition, under NIR light, the surface coating exhibited photothermal conversion effect, and gold nanoparticles and the antibiotic can be released from the coating. This improved the antibacterial properties of PEEK materials. Moreover, the coating was more conducive to the early adhesion of bone mesenchymal stem cells. The results of in vitro and in vivo osteogenic activity studies showed that the developed coating promoted osseointegration of PEEK implants, and NIR light irradiation further improved the antibacterial ability and osteogenic activity of PEEK implants. Through RNA sequencing, the potential underlying mechanism of promoting bone formation of the AuNPs coating combined metronidazole was interpreted. In summary, the developed coating is a potential surface treatment strategy that endows PEEK with enhanced osseointegration and antibacterial properties.