Developing a novel resorptive hydroxyapatite-based bone substitute for over-critical size defect reconstruction: physicochemical and biological characterization and proof of concept in segmental rabbit's ulna reconstruction.

The aim of this study was to develop novel hydroxyapatite (HAP)-based bioactive bone replacement materials for segmental osteotomy reconstruction. Customized three-dimensional (3D) bone construct was manufactured from nanohydroxyapatite (nHAP) with poly(lactide-co-glycolide) (PLGA) coating using 3D models derived from the computed tomography (CT) scanning of the rabbit's ulna and gradient 3D printing of the bone substitute mimicking the anatomical shape of the natural bone defect. Engineered construct revealed adequate micro-architectural design for successful bone regeneration having a total porosity of 64% and an average pore size of 256 µm. Radiography and micro-CT analysis depicted new bone apposition through the whole length of the reconstructed ulna with a small area of non-resorbed construct in the central area of defect. Histological analysis revealed new bone formation with both endochondral and endesmal type of ossification. Immunohistochemistry analysis depicted the presence of bone formation indicators - bone morphogenetic protein (BMP), osteocalcin (OCN) and osteopontin (OPN) within newly formed bone. Manufactured personalized construct acts as a "smart" responsive biomaterial capable of modulating the functionality and potential for the personalized bone reconstruction on a clinically relevant length scale.

Mandibular lateral deviation induces alteration in vascular endothelial growth factor expression and oxidative stress/nitric oxide generation in rat condyle, synovial membrane and masseter muscle.

OBJECTIVE: We aimed to investigate alteration in cellular signaling mediated by vascular endothelial growth factor (VEGF) and parameters of oxidative stress/nitric oxide generation, superoxide dismutase (SOD) and neuronal nitric oxide synthase (nNOS), underlying altered functional mechanical loading of TMJ (temporomandibular joint) during lateral mandibular deviation. DESIGN: Thirty-eight 5-week-old male Wistar rats were divided into experimental group, which received acrylic resin appliance that shifted mandible to the left during closure, and control group. Computed tomography and histomorphometry were used for condyle analyses, while samples of condyle, synovial membrane and m. masseter were analyzed with enzyme-linked immunosorbent assay and spectrophotometry to determine VEGF and nNOS protein concentrations, and SOD activity. RESULTS: Experimental group of rats developed smaller and asymmetrical mandibles. Less of new bone and cartilage formation and larger bone marrow cavities area were found in the experimental group. Higher VEGF expression in condyle and m. masseter as well as higher nNOS expression in m. masseter and synovial membrane were found in the experimental compared to the control group. Alteration of SOD activity was found in m. masseter and synovial membrane in the experimental group. CONCLUSIONS: Lateral mandibular deviation induces mandibular and condylar morphological changes as well as significant cellular signaling alterations in condyle, synovial membrane and masticatory muscle. Cellular VEGF protein overexpression and oxidative stress/nitric oxide disbalance could be the mechanisms underlying unbalanced functional TMJ loading due to mandibular deviation.

Histological Effects of Enamel Matrix Derivative on Exposed Dental Pulp.

INTRODUCTION: Direct pulp capping procedure is a therapeutic application of a drug on exposed tooth pulp in order to ensure the closure of the pulp chamber and to allow the healing process to take place. OBJECTIVE: The aim of this study was to examine the histological effects of Emdogain® on exposed tooth pulp of a Vietnamese pig (Sus scrofa verus). METHODS: The study comprised 20 teeth of a Vietnamese pig. After class V preparation on the buccal surfaces of incisors, canines and first premolars, pulp was exposed. In the experimental group, the perforations were capped with Emdogain® (Straumann, Basel, Switzerland), while in the control group pulp capping was performed with MTA® (Dentsply Tulsa Dental, Johnson City, TN, USA). All cavities were restored with glass-ionomer cement (GC Fuji VIII, GC Corporation, Tokyo, Japan). The observational period was 28 days, after which the animal was sacrificed and histological preparations were made. A light microscope was used to analyze dentin bridge formation, tissue reorganization and inflammation, and the presence of bacteria in the pulp. RESULTS: The formation of dentin bridge was observed in the experimental and control groups. Inflammation of the pulp was mild to moderate in both groups. Angiogenesis and many odontoblast-like cells, responsible for dentin bridge formation, were observed. Necrosis was not observed in any case, nor were bacteria present in the pulp. CONCLUSION: Histological analysis indicated a favorable therapeutic effect of Emdogain® Gel in direct pulp capping of Vietnamese pigs. Pulp reaction was similar to that of MTA®.

The closure of oroantral communications with resorbable PLGA-coated beta-TCP root analogs, hemostatic gauze, or buccal flaps: a prospective study.

OBJECTIVE: The aim of this study was to compare the treatment of oroantral communications (OACs) with bioresorbable root analogs made of poly(lactide-co-glycolide) (PLGA)-coated beta-tricalcium phosphate (beta-TCP), hemostatic gauze or a buccal flap technique. STUDY DESIGN: In this prospective clinical study, 30 patients with oroantral communications were randomly assigned to a treatment. Clinical success, vestibular depth at the defect site, pain, and swelling were monitored. RESULTS: The OAC closure was successful in all cases. The vestibular depth stayed constant in the groups treated with the PLGA-beta-TCP composite or hemostatic gauze. In contrast, a vestibular depth reduction of 1.2 +/- 0.2 mm was observed in the buccal flap group, indicating atrophy of the alveolar ridge in these patients. Furthermore, pain and swelling were more pronounced in this group. CONCLUSION: Closures of OACs with PLGA-beta-TCP composite or hemostatic gauze are reliable minimally invasive methods that minimize atrophy of the alveolar ridge, swelling, and pain compared with a buccal flap technique.

[Comparative immunohistochemical and quantitative analysis of inflammatory cells in symptomatic and asymptomatic chronic periapical lesions].

BACKGROUND/AIM: It has been demonstrated that lymphocytes, plasma cells, macrophages and neutrophil granulocytes represent the predominant cells of the inflammatory lesion of the dental granulomas. Other cells, such as mast cells, eosinophils, dendritic cells comprise minor, but functionally important cell populations. Most of the data considering cells that take part in these processes have been derived from immunohistological studies. This study was undertaken with the aim to determine the phenotype profile of inflammatory cells of dental granulomas using immunohistochemical method in order to study the differences of their quantitative properties and distribution between symptomatic and asymptomatic lesions. METHODS: The material for the analysis originated from 42 individuals with clinic and radiographic diagnosis of chronic periapical lesions. The tissue was take either during the periradicular surgery, or tooth extraction. Cryostat tissue sections were stained using the alkaline phosphatase-antialkaline phosphatase assay (APAAP). This method is highly valid and sensitive using a panel of specific monoclonal antibodies: CD3, CD4, CD8, CD19, CD38, CD14, CD1a, CD83, CD80, CD86, CD45 and CD123. RESULTS: The composition of the cell population revealed that there was no homogenous and site-specific pattern of the distribution of inflammatory cells. The results of our investigation revealed that the majority of inflammatory cells comprised lymphocytes and plasma cells, followed by subpopulations CD4+, CD8+ and CD14+ cells. Much lower in number were CD80+, CD86+ and CD83+ and CD1a+ cells. There were no statistically significant differences in mean values of inflammatory cells number between symtomatic and asymptomatic lesions, with the exception of CD86+ cells, the number of which was statistically higher in symptomatic lesions. CONCLUSION: Inflamatory infiltrate cells in dental granulomas are dominated by T- and B-lymphocytes. It points out the complexity of immunopathogenic events in imitiating and progressing of dental granulomas that involve mechanisms of both cellular and humoral immunity. Regarding the quantitative presence of immunocompetent cells in symptomatic and asymptomatic lesions no statistically significant difference was determined unless in mature dendritic cells present in symptomatic lesions.

[Histological evaluation of platelet rich plasma and hydroxyapatite in apexogenesis: study on experimental animals].

BACKGROUND/AIM: There are very few data about the effects of endogenous growth factors in vital pulp therapy, and still they are often controversial. The aim of the study was to evaluate the effects of platelet rich plasma (PRP) in conjugation with hydroxyapatite (HAP), as pulp capping materials, to root and periodontium formation. METHODS: Eight young monkeys (Cercopithecus Aethiops) with permanent dentition and incomplete root formation were involved in this study. After pulpotomy, the pulp lesion was capped with calcium hydroxide (control), hydroxyapatite (experimental group I) or hydroxyapatite in conjugation with PRP (experimental group II). Six months later, the animals were sacrificed, the tissue was removed en block, and prepared for the histological analysis in a routine way. RESULTS: The results of the histological analysis revealed that healing process was characterised by dentin bridge formation, maintained morphological and functional integrity of dental pulp and complete formation of dental root and surrounding periodontium. The inflammatory reaction was scored as mild to moderate, in almost all the samples in all groups, suggesting the biocompatibility of the used materials. CONCLUSION: Materials used in this study are convenient as capping agents, contributing maintaining the integrity of the pulp tissue and facilitating root and periodontium forma tion. According to histological data it could be suggested that hydroxyapatite in conjugation with endogenous growth factors, represents superior alternative to other materials used in this study.

[Preimplant preparation of the extraction alveolus with the deproteinized bovine bone and calcium-sulphate].

BACKGROUND: Different materials are used to prevent the resorption of alveolar bone. The aim of this report was to show the radiographical and histological results prior to implant insertion, when a deproteinized bovine bone mineral (BioOss) and calcium-sulphate were placed into the extraction socket immediatelly after the tooth removal. CASE REPORT: A 22-year-old woman was scheduled for the removal of the second lower molar when the extraction socket was filled with BioOss covered with calcium-sulphate as a resorbable membrane. Primary closure of the surgical site was performed. Radiography was done 4 and 12 months later. One year after the surgery, when the implant was inserted, a biopsy of the new regenerated bone was obtained for the histological evaluation. The lamellar bone was evident using both materials. The resorption of BioOss was slow and the connective tissue was observed. CONCLUSION: Both materials had biocompatible and oseoconductive properties. One year after the grafting procedure, we observed the lamellar bone and partial resorption of BioOss, while calcium-sulphate showed no significant effect as a resorbable membrane.