A preliminary study of cell-based bone tissue engineering into 3D-printed ß-tricalcium phosphate scaffolds and polydioxanone membranes.

Treatment of complex craniofacial deformities is still a challenge for medicine and dentistry because few approach therapies are available on the market that allow rehabilitation using 3D-printed medical devices. Thus, this study aims to create a scaffold with a morphology that simulates bone tissue, able to create a favorable environment for the development and differentiation of osteogenic cells. Moreover, its association with Plenum Guide, through cell-based tissue engineering (ASCs) for guided bone regeneration in critical rat calvarial defects. The manufacturing and characterization of 3D-printed ß-TCP scaffolds for experimental surgery was performed. Nine male rats were divided into three groups: ß-TCP + PDO membrane (TCP/PG), ß-TCP/ASCs + PDO membrane (TCPasc/PG), and ß-TCP/ASCs + PDO membrane/ASCs (TCPasc/PGasc). A surgical defect with a 5-mm diameter was performed in the right parietal bone, and the defect was filled with the 3D-printed ß-TCP scaffold and PDO membrane with or without ASCs. The animals were euthanized 7, 14, and 30 days after the surgical procedure for histomorphometric and immunolabeling analyses. 3D-printed ß-TCP scaffolds were created with a 404 ± 0.0238 µm gyroid macro-pore and, the association to cell-based therapy promotes, especially in the TCPasc/PGasc group, a bone area formation at the defect border region and the center of the defect. The use of 3D-printed ß-TCP scaffolds and PDO membranes associated with cell-based therapy could improve and accelerate guided bone regeneration, promoting an increase in osteogenic capacity and reducing the time involved in the bone formation process. Moreover, using ASCs optimized the bioceramics by increasing its osteoinductive and osteoprogenitor capacity and, even with the resorption of the printed scaffold, aided as a scaffold for mesenchymal cell differentiation, as well as in bone tissue formation.

Teriparatide improves microarchitectural characteristics of peri-implant bone in orchiectomized rats.

This study evaluated the peri-implant bone repair in orchiectomized rats receiving intermittently PTH 1-34. The treatment returned the bone quality and quantity of the animals to normal in the computerized microtomography, laser confocal microscopy, and histological analysis. The PTH 1-34 promoted marked bone formation with increased volume, improved quality, and greater bone turnover. INTRODUCTION: Osteoporosis can be a problem in implant osseointegration. So this study aimed to evaluate the quantity and quality of peri-implant bone repair in orchiectomized Wistar rats receiving intermittently administered PTH 1-34. METHODS: Animals (n = 24) were divided into 3 groups: healthy control (SHAM), orchiectomized (ORQ), and orchiectomized and treated with 0.5 µg/kg/day PTH 1-34 (TERI), and each received an implant in the right and left tibial metaphysis, which was allowed to repair for 60 days. The resultant bone formation was evaluated through computerized microtomography (micro-CT) to compare the percent bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular number and separation (Tb.N, Tb.Sp), and bone implant contact (BIC) through the intersection surface (i.S) between groups. Laser confocal microscopy was used to evaluate fluorochrome areas for mineral apposition rate (MAR) and neoformed bone area (NBA). In addition, histological evaluation of calcified tissues with Stevenel blue and alizarin red staining was performed. RESULTS: Treatment with PTH 1-34 returned the bone quality and quantity of the osteoporotic animal to normal, as the TERI group presented statistically significant higher values for BV/TV, Tb.Th, and BIC parameters compared with ORQ (p < 0.05), but when compared with SHAM (p > 0.05), no statistical difference was noted. In addition, in the bone turnover analysis (MAR, NBA) for TERI, the highest results are presented, followed by SHAM, and then ORQ (TERI × ORQ: p < 0.05). CONCLUSIONS: Intermittent treatment with PTH 1-34 on orchiectomized animals promoted marked bone formation with increased volume, improved quality, and greater bone turnover in the peri-implant space, returning the bone quality and quantity to the present standard in healthy animals.

Raloxifene enhances peri-implant bone healing in osteoporotic rats.

The aim of this study was to evaluate bone healing at the bone-implant interface in rats with induced osteoporosis. The rats underwent a bilateral ovariectomy (OVX) and were fed a low calcium and phosphate diet. The OVX rats were divided into three groups: one was treated with raloxifene (OVX-RAL), one with alendronate (OVX-ALE), and one received no medication (OVX-NT). The control group rats (SHAM-DN) underwent sham surgery and were fed a normal diet. Each animal received one implant in each tibia: a machined surface implant in the right tibia and an implant with surface etching in the left tibia. All animals were euthanized after 42 days. Analysis of variance (ANOVA) and Tukey post hoc tests were applied to the biomechanics (reverse torque) and bone-implant contact (BIC) data (P<0.05). The RAL and ALE groups showed improved peri-implant bone healing. However, the ALE group showed no significant difference from the OVX-NT group. Surface treatment promoted higher corticalization at the bone-implant interface, but showed the same characteristics of mature bone and bone neoformation in concentric laminations as the machined implant. There were no statistically significant differences in reverse torque (P=0.861) or BIC (P=0.745) between the OVX-RAL and SHAM-DN groups. Therefore, the use of raloxifene resulted in good biomechanical, BIC, and histological findings in the treatment of induced osteoporosis in rats.

Temporal localization of osteocalcin protein during healing of tooth extraction sockets in rats.

AIM: The aim of this study was to evaluate the expression of osteocalcin protein during the alveolar bone healing process in rats. METHODS: Twenty four rats were used in this study and, after anesthetic induction, they had their right upper incisors extracted. At 7, 14, 21 and 28 days after the tooth extraction, the animals were injected 4% formaldehyde. The histological tissue pieces were colored in hematoxilin and eosin and the immunohistochemistry reaction for osteocalcin was performed. RESULTS: At seven days lesser neoformed trabeculae bone and a small quantity of osteocalcin labeling were observed. At 14 and 21 days a larger quantity of neoformed trabeculae bone and higher osteocalcin values were detected. At 28 days the largest quantity of neoformed trabeculae bone and a decrease on the amount of osteocalcin immunolabelling were noticed. CONCLUSION: According to our results and considering the limits of the present study it is possible to conclude that a greater osteocalcin expression is observed at 14 and 21 days postoperatively, characterizing the periods when intense mineralization of the bone tissue occurs during the alveolar bone healing process.

Homogenous implant in rat tibias of matrix preserved in 98% glycerin: histomorphologic study.

As a chemical medium for preservation of tissues, glycerin has shown good results because it maintains the cellular integrity despite the tissue dehydration it causes. Taking advantage of the osteoinducing properties of the osseous matrix and glycerin as a proper medium for tissue preservation, osseous matrix was implanted in rat tibias. Twenty-four rats were used, each receiving two surgical wounds. In one of the wounds an osseous matrix preserved in 98% glycerin was implanted and the other received a matrix without preservatives. Six animals were sacrificed on days 10, 20, 30 and 60 post-implant. After routine histological processing, the specimens were stained in hematoxylin-eosin and Masson's trichrome. The results showed that the matrixes preserved in glycerin presented faster resorption with replacement by newly formed tissue.

Genotoxicity of fractionated organic material in airborne particles from São Paulo, Brazil.

Particulate matter less than 10 microns aerodynamic diameter (PM10) is associated with adverse health effects including increased respiratory problems and mortality. PM10 is also associated with increases in cancer in some urban areas. Identification of toxic compounds in PM10 is a step toward estimating exposure to these compounds and evaluating their public health risk. However, the toxic compounds on PM10 are part of a highly complex mixture of compounds that makes chemical characterization difficult. Before this study, there has been little investigation of genotoxic compounds in particulate matter from Latin American cities. Here, both bioassay (mutagenicity) and chemical analyses were conducted with organic solvent extracts of PM10 collected from São Paulo, a major Brazilian city. Sequential extraction in dichloromethane (DCM) followed by acetone (ACE) yielded 20.3% and 10.2% of the total mass, respectively. Non-polar and moderately polar organic material solubilized in DCM. ACE extracted more polar organic species and some inorganic ions. Both extracts were fractionated separately using cyanopropyl-bonded silica chromatography with organic solvents of increasing polarity. The mass distribution among the fractions was measured. The mutagenic activity of the fractions was assayed using the microsuspension procedure with the Salmonella typhimurium tester strain TA98, with and without addition of metabolic enzymes (S9). The DCM extract had about four times higher mutagenic activity than the ACE extract. In general, addition of S9 resulted in an increase in mutagenicity of DCM fractions, but a decrease for the ACE extract. Most of the activity was concentrated in fractions in the mid-range of polarity within both the DCM and ACE extracts. The fractions were analyzed by gas chromatography with mass selective detection (GC/MS) without derivatization. The most mutagenic fractions in the DCM extract contained ketones, aldehydes, and quinolines. The most mutagenic ACE fraction had ketones, carboxylic acids, and aldehydes.

Surgical correction of nipple hypertrophy.

In this report, a surgical technique for reduction of nipple height and diameter without affecting the central column is described. The results are discussed in light of existing literature.

Interference of the blood clot on granulation tissue formation after tooth extraction. Histomorphological study in rats.

The interference of a blood clot in the first postoperative hours of dental extraction wounds was studied in rats. Sixty male albino rats were divided into two groups: Group I, immediately after extraction of right maxillary incisor the gingival mucosa was approximated and sutured; Group II, after 6 to 8 minutes postoperatively the blood clot was removed with saline irrigation and absorbent paper cones. The mucosa was then approximated and sutured. Six animals in each group were sacrificed after 12 hours, 1, 4, 7 and 10 days. There was a profound delay in healing in Group II since, although a new blood clot was later formed, it was not organized. The quality and the constitution, maintenance and retraction of the clot are the regulating factors in connective tissue formation during alveolar healing.