Evaluation of Osseointegration and Bone Healing Using Pure-Phase ß - TCP Ceramic Implant in Bone Critical Defects. A Systematic Review.

Background: The gold standard for osseointegration remains the autogenous bone graft, but biomaterials such as Beta - tricalcium phosphate (ß - TCP) in its pure-phase showed promising results to be practical bone substitutes. This kind of implants are optimal candidates for bone integration due to their osseoconductive, biocompatibility, bioactivity, and absorptive properties. Methods: A systematic review was conducted using 5 databases (Cochrane Library, PubMed, Scielo, Medline-Bireme and Google Scholar) for searching published studies between January 1st 2011 and June 15th 2021. Only clinical and experimental studies, and case reports were included in this research. Human and animal studies published only in Portuguese or English with clinical, radiologic, and histologic evidence of new bone formation, osseoconduction, and osseointegration were included. This systematic review was reported according to PRISMA guidelines. Results: Approximately 14.554 articles were initially found, but after advanced searching using specific including and excluding keywords, matching Boolean operators "AND," "OR" and "NOT," and after excluding duplicates, a total of 12 articles were included for this systematic review, including experimental works, a retrospective study, a randomized controlled clinical study, a randomized prospective study, a prospective observational study, and a case report. All articles showed 100% effectiveness in bone integration after ß - TCP implantation by clinical, image and/or histologic assessment. Implant shape and porosity seem to have influence in osseointegration process. ß - TCP can give predictable, sustainable, and adequate new bone formation with the least infection rates in implant placement cases and patient morbidity, which is the current goals for bone integration, augmentation and replacement. Conclusion: ß - TCP in its pure-phase is widely used in dentistry and maxillofacial surgery, but there is a lack of information about the use of this biomaterial for filling critical segmental defects of long bones in veterinary medicine. In this area, only experimental studies in small defects were carried out, with no clinical cases performed in animals with a longer observation time. ß - TCP can produce predictable, sustainable, and adequate bone formation, with minimal infection rates and low patient morbidity. But more clinical studies in the future, demonstrating specific metric measurements in relation to bone consolidation, as well as showing results using other shapes of this implant are needed to evaluate further in depth osseoconductive and osseointegrative characteristics of this biomaterial, in order to develop new comparisons and quantitative analyses for its use in veterinary medicine as a bone replacement.

Brushite bone cement containing polyethylene glycol for bone regeneration.

BACKGROUND: Bone cements aid in bone regeneration; however, if the handling time is not well established for the material to harden, complications may arise. OBJECTIVE: This work investigates the effect of using polyethylene glycol (PEG) and characterize it in brushite bone cement in order to obtain desirable handling times as well as its regeneration in vivo to analyse if addition of this polymer may significantly modify its properties. METHODS: PEG 4000 was synthesised with wollastonite by phosphorization reaction in order to form brushite which was further cured by oven drying. They were further characterised and tested in vivo as tibial bone defect model using rabbits. RESULTS: Addition of PEG exhibited handling times of 60 min with a low increase in temperature when curing. Brushite phase of ∼71% was obtained after cement hardening with good compressive strength (25 MPa) and decent values of porosity (33%). In vivo presented that, at 40 days postoperatively, accelerated bone neoformation with partial consolidation at 30 days and total after 60 days when using bone cement. CONCLUSIONS: Addition of PEG does not disrupt the beneficial properties of the bone cement and can be a potential alternative to control the time-temperature profile of hardening these materials.

Injectable bone substitute based on chitosan with polyethylene glycol polymeric solution and biphasic calcium phosphate microspheres.

We described a method to produce an injectable bone substitute consisting of a solid and liquid phase, this solid was formed using the coacervation method consisting of a mixture of Hydroxyapatite (HAp) and beta-Tricalcium Phosphate (ß-TCP) which the sodium alginate - precursor - was removed during sinterization. The biphasic calcium phosphate microspheres had varying size distributions depending on the flow rate and these microspheres were mixed with a polymeric solution, chitosan and polyethylene glycol, and depending on the ratio of these phases, the injectability results varied. Nonetheless, the force required for complete removal will not disrupt the accuracy of injection into the bone defect while the biomaterial exhibited no cytotoxicity with promising results from in vivo using tibia bone defect in rabbits at 30 and 60 days whereas bone repair was more intense and accentuated with the usage of the biomaterial, and was gradually absorbed during the evaluated periods.

Platelet-Rich Plasma, Hydroxyapatite, and Chitosan in the Bone and Cartilaginous Regeneration of Femoral Trochlea in Rabbits: Clinical, Radiographic, and Histomorphometric Evaluations.

The aim of this study was to evaluate the trochlear bone and cartilaginous regeneration of rabbits using the association of PRP, chitosan, and hydroxyapatite. Hole was made in rabbit troches, one hole in each animal remained empty (group C), and one was filled by a combination of PRP, chitosan, and hydroxyapatite (group T). Clinical-orthopedic, radiographic, and histomorphometric evaluations were performed. Clinical-orthopedic evaluation showed lameness of two members of the T group and one member of group C. The radiographic evaluation showed that the T group showed absence of subchondral bone reaction (33%). The presence of moderate subchondral bone reaction was more frequently reported in group C with 67%. Microscopic evaluation revealed a presence of tissue neoformation, composed of connective tissue. Microscopic findings were similar in both groups, with a difference in the amount of neoformed tissue being perceptible, which was confirmed after the morphometric analysis, which revealed a significant difference in the quantity of newly formed tissue at the bone/cartilage/implant interface. The composite base of the association of chitosan, hydroxyapatite, and platelet-rich plasma favored bone and cartilage healing.

Intratesticular injection of a zinc-based solution as a contraceptive for dogs.

The objective of the present study was to evaluate, by light and transmission electron microscopy, the efficacy of a single intratesticular injection of a novel zinc-based solution, as a contraceptive for male dogs. Fifteen mongrel dogs were assigned to three groups (five dogs/group). Group 1, the control group, which consisted of animals ranging from 8 mo to 4 yr, was injected with saline solution. Group 2, which consisted of animals ranging from 8 mo to 1 yr old and Group 3, animals ranging from 2 to 4 yr old, were injected with a zinc-based solution (0.2-1.0mL; volume based on testicular width). There were no histopathological changes detected in testes from control dogs. Histological examination of treated groups revealed degeneration, vacuolation, fewer germ cells, formation of multinucleated giant cells, and a lack of elongated spermatids in atrophic seminiferous tubules. Leydig cells had varying degrees of lipid degeneration and necrosis. The majority of seminiferous tubules in all zinc-treated dogs were lined only by Sertoli cells, which were vacuolated. Ultrastructure of testis of treated groups had degenerate Sertoli and Leydig cells, characterized by numerous mitochondria with the lack of a matrix and agglomeration of lysosomal bodies. The cytoplasm of elongated spermatids was characterized by tubules of hyperplastic and hypertrophic smooth endoplasmic reticulum and numerous Golgi apparati. Round spermatids in Golgi phase had lysis of acrosomal vesicles. The degree of histological changes suggested irreversibility. In conclusion, intratesticular injection of a zinc-based solution effectively impaired spermatogenesis.