Cell-Based Regenerative Endodontics for the Treatment of Irreversible Pulpitis: AnIn VivoInvestigation.

INTRODUCTION: This study aims to investigate the ability of umbilical cord mesenchymal stem cells (UC-MSC) to enhance the regeneration of pulp-dentin complex in immature permanent teeth with irreversible pulpitis. METHODS: A total of 32 mandibular premolar teeth with immature apices in 5 dogs were used in this in-vivo randomized controlled trial (RCT). Eight healthy teeth without pre-existing pathosis served as the positive control samples and received no treatment, while in another 8 teeth, the pulp was completely extirpated (negative control). Class V cavities were prepared to induce inflammation in the remaining 16 teeth (groups 3 and 4) and the pulp was extirpated 2-4 mm short of the radiographic apex. Of the 16, the 8 teeth in group 4 received 1 mL of cord blood stem cells with a hydrogel scaffold. Blood clots were covered with mineral trioxide aggregates at the cementoenamel junction in the experimental groups, and teeth were filled with RMGI and composite. Three months later, block sections were removed for histologic evaluations for the evaluation of postoperative apical closure, degree of inflammation, and presence of normal pulp tissue. The data were statistically analyzed with the chi-square test (P < .05). RESULTS: All teeth with complete pulp extirpation demonstrated pulpal necrosis with no postoperative closure of their apices, while apical closure was seen in all the teeth in the remaining groups. There was a statistically significant (P < .001) difference in the presence of inflammation and normal pulp tissue between the experimental groups. The teeth in group 3 showed normal pulp tissue extending to the level of MTA, but there was inflammation within the canal space. In contrast, the teeth in the UC-MSC group demonstrated organized, normal pulp tissue with no inflammation. CONCLUSION: Based on these results, the regeneration of the pulp-dentin complex is possible with no inflammation when UC-MSCs are used and 2-4 mm of the apical pulp remains intact in immature teeth with irreversible pulpitis.

Correlation between gray values in cone-beam computed tomography and histomorphometric analysis.

Purpose: The aim of this study was to analyze the relationships between bone density measurements obtained using cone-beam computed tomography (CBCT) and morphometric parameters of bone determined by histomorphometric analysis. Materials and Methods: In this in vivo study, 30 samples from the maxillary bones of 7 sheep were acquired using a trephine. The bone samples were returned to their original sites, and the sheep heads were imaged using CBCT. On the CBCT images, gray values were calculated. In the histomorphometric analysis, the total bone volume, the trabecular bone volume (referred to simply as bone volume), and the trabecular thickness were assessed. Results: Statistical testing showed significant correlations between CBCT gray values and total bone volume (r=0.537, P=0.002), bone volume (r=0.672, P<0.001), and trabecular thickness (r=0.692, P<0.001), as determined via the histomorphometric analysis. Conclusion: The results indicate a significant and acceptable association between CBCT gray values and bone volume, suggesting that CBCT may be used in bone densitometry.

The effect of platelet-rich plasma on human mesenchymal stem cell-induced bone regeneration of canine alveolar defects with calcium phosphate-based scaffolds.

OBJECTIVES: Autologous bone transplantation known as the "gold standard" to reconstruction of osseous defects has known disadvantages. This study was designed to explore the effects of hydroxy-apatite/tricalcium-phosphate (HA/TCP) and platelet-rich plasma (PRP) on the osteogenesis ability of human adipose-derived mesenchymal stem cells (hAdMSCs) in vitro and in vivo. MATERIALS AND METHODS: hAdMSCs were incubated with HA/TCP granules and/or PRP in vitro and then, cell proliferation and differentiation was assessed by MTT assay, AZR S staining and SEM examination. In vivo, four cylindrical defects were drilled in the mandibular bones of 5 mongrel dogs and divided randomly into the following groups: I-autologous crushed bone, II- no filling material, III- HA/TCP and PRP, IV- PRP-enriched hAdMSCs seeded on HA/TCP granules. Inserted hAdMSCs were labeled to trace their contribution to bone tissue regeneration. Finally, cell tracing and tissue regeneration were evaluated by immunohistochemistry and histomorphometry methods, respectively. RESULTS: In vitro, co-incubation with HA/TCP granules significantly reduced proliferation and osteogenic differentiation ability of hAdMSCs; while PRP application promoted these capacities (P<0.05). In vivo, PRP-enriched hAdMSCs seeded on HA/TCP granules induced considerable bone formation in osseous defects (P<0.05). It was obviously shown that hAdMSCs were incorporated into the newly-formed bone. CONCLUSION: Based on this study, application of stem cells could offer a helpful therapeutic tool in bone tissue regeneration. Although inserted hAdMSCs were identifiable throughout the newly-formed bone tissue, their few number could be an indicator of indirect role of hAdMSCs in tissue regeneration.

Effects of Human Adipose-derived Stem Cells and Platelet-Rich Plasma on Healing Response of Canine Alveolar Surgical Bone Defects.

BACKGROUND: Due to the known disadvantages of autologous bone grafting, tissue engineering approaches have become an attractive method for ridge augmentation in dentistry. To the best of our knowledge, this is the first study conducted to evaluate the potential therapeutic capacity of PRP-assisted hADSCs seeded on HA/TCP granules on regenerative healing response of canine alveolar surgical bone defects. This could offer a great advantage to alternative approaches of bone tissue healing-induced therapies at clinically chair-side procedures. METHODS: Cylindrical through-and-through defects were drilled in the mandibular plate of 5 mongrel dogs and filled randomly as following: I- autologous crushed mandibular bone, II- no filling material, III- HA/TCP granules in combination with PRP, and IV- PRP-enriched hADSCs seeded on HA/TCP granules. After the completion of an 8-week period of healing, radiographic, histological and histomorphometrical analysis of osteocyte number, newly-formed vessels and marrow spaces were used for evaluation and comparison of the mentioned groups. Furthermore, the buccal side of mandibular alveolar bone of every individual animal was drilled as normal control samples (n=5). RESULTS: Our results revealed that hADSCs subcultured on HA/TCP granules in combination with PRP significantly promoted bone tissue regeneration as compared with those defects treated only with PRP and HA/TCP granules (P<0.05). CONCLUSION: In conclusion, our results indicated that application of PRP-assisted hADSCs could induce bone tissue regeneration in canine alveolar bone defects and thus, present a helpful alternative in bone tissue regeneration.

The effects of Nigella sativa on neural damage after pentylenetetrazole induced seizures in rats.

Nigella sativa (NS) has been suggested to have neuroprotective and anti-seizures properties. The aim of current study was to investigate the effects of NS hydro-alcoholic extract on neural damage after pentylenetetrazole (PTZ) - induced repeated seizures. The rats were divided into five groups: (1) control (saline), (2) PTZ (50 mg/kg, i.p.), (3-5) PTZ-NS 100, PTZ-NS 200 and PTZ-NS 400 (100, 200 and 400 mg/kg of NS extract respectively, 30 min prior to each PTZ injection on 5 consecutive days). The passive avoidance (PA) test was done and the brains were then removed for histological measurements. The PTZ-NS 100, PTZ-NS 200 and PTZ-NS 400 groups had lower seizure scores than PTZ group (P < 0.01 and P < 0.001). The latency to enter the dark compartment by the animals of PTZ group was lower than control in PA test (P < 0.01). Pre-treatment by 400 mg/kg of the extract increased the latency to enter the dark compartment (P < 0.05). Meanwhile, different doses of the extract inhibited production of dark neurons in different regions of hippocampus (P < 0.001). The present study allows us to suggest that the NS possesses a potential ability to prevent hippocampal neural damage which is accompanied with improving effects on memory.

Anticonvulsant and neuroprotective effects of Rosa damascena hydro-alcoholic extract on rat hippocampus.

OBJECTIVE: Previously, analgesic, hypnotic, and anticonvulsant effects have been suggested for Rosa damascena (R. damascena). In the present study, possible anti-seizure and neuro-protective effects of hydro-alcoholic extract of R. damascena has been investigated after inducing seizures in rats by pentylenetetrazole (PTZ). MATERIALS AND METHODS: The rats were divided to five groups: (1) CONTROL: received saline, (2) PTZ: 100 mg/kg, i.p., (3) PTZ- Extract 50 mg/kg (PTZ-Ext 50), (4) PTZ- Extract 100 mg/kg (PTZ-Ext 100), and (5) PTZ- Extract 200 mg/kg (PTZ-Ext 200) groups which were treated with 50, 100, and 200 mg/kg respectively of hydro-alcoholic extract of R. dam ascena for one week before PTZ injection. The animals were examined for electrocorticography (ECoG) recording and finally, the brains were removed for histological study. RESULTS: The hydro-alcoholic extract of R. dam ascena significantly prolonged the latency of seizure attacks and reduced the frequency and amplitude of epileptiform burst discharges induced by PTZ injection. Moreover, all three doses of the extract significantly inhibited production of dark neurons in different regions of the hippocampus in the mentioned animal model. CONCLUSION: The present study showed that the hydro-alcoholic extract of R. dam ascena has anticonvulsant and neuroprotective effects. More investigations are needed to be done in order to better understand the responsible compound(s) as well as the possible mechanism(s).