Hard tissue formation in pulpotomized primary teeth in dogs with nanomaterials MCM-48 and MCM-48/hydroxyapatite: an in vivo animal study.

BACKGROUND: This animal study sought to evaluate two novel nanomaterials for pulpotomy of primary teeth and assess the short-term pulpal response and hard tissue formation in dogs. The results were compared with mineral trioxide aggregate (MTA). METHODS: This in vivo animal study on dogs evaluated 48 primary premolar teeth of 4 mongrel female dogs the age of 6-8 weeks, randomly divided into four groups (n = 12). The teeth underwent complete pulpotomy under general anesthesia. The pulp tissue was capped with MCM-48, MCM-48/Hydroxyapatite (HA), MTA (positive control), and gutta-percha (negative control), and the teeth were restored with intermediate restorative material (IRM) paste and amalgam. After 4-6 weeks, the teeth were extracted and histologically analyzed to assess the pulpal response to the pulpotomy agent. RESULTS: The data were analyzed using the Kruskal‒Wallis, Fisher's exact, Spearman's, and Mann‒Whitney tests. The four groups were not significantly different regarding the severity of inflammation (P = 0.53), extent of inflammation (P = 0.72), necrosis (P = 0.361), severity of edema (P = 0.52), extent of edema (P = 0.06), or connective tissue formation (P = 0.064). A significant correlation was noted between the severity and extent of inflammation (r = 0.954, P < 0.001). The four groups were significantly different regarding the frequency of bone formation (P = 0.012), extent of connective tissue formation (P = 0.047), severity of congestion (P = 0.02), and extent of congestion (P = 0.01). No bone formation was noted in the gutta-percha group. The type of newly formed bone was not significantly different among the three experimental groups (P = 0.320). CONCLUSION: MCM-48 and MCM-48/HA are bioactive nanomaterials that may serve as alternatives for pulpotomy of primary teeth due to their ability to induce hard tissue formation. The MCM-48 and MCM-48/HA mesoporous silica nanomaterials have the potential to induce osteogenesis and tertiary (reparative) dentin formation.

Effects of remifentanil on the recovery quality among pediatric candidates for dental procedures under general anesthesia.

Background: Remifentanil is a short-acting synthetic opioid, seems to facilitate hospital discharge, induce less agitation and better recovery quality. The aim of this study was to investigate the effects of remifentanil on the quality of recovery among healthy children who were candidate for dental procedures under general anesthesia. Materials and Methods: This study was a double blind randomized controlled clinical trial on healthy children who referred to the Department of Pediatric dentistry, School of Dentistry, Isfahan University of Medical Sciences. Both groups were anaesthetized using 5 mg/kg thiopental sodium, 1 µg/kg fentanyl and 0.6 µg/kg atracurium. The first group received propofol to maintain anesthesia and the second group was given remifentanil along with propofol. Then, the time span to regain consciousness, level of agitation during recovery and time of discharge were monitored and compared between the two groups. Data were analyzed using the Mann-Whitney U-test, and the Kruskal-Wallis test at P < 0.05 level of significance. Results: Findings showed that the propofol + remifentanil group recovered faster than the propofol group. Chi-square test showed a significant difference in recovery time between the two groups (P < 0.05). About 45 min after regaining consciousness, the mean pediatric anesthesia emergence delirium score in the propofol group was 4.02 ± 2.19 and was significantly higher than the propofol + remifentanil group (3.02 ± 2.83) (P < 0.05). In addition, the mean Postanesthetic Discharge Scoring System score in the propofol group was 6.04 ± 1.74 and was significantly higher than the propofol + remifentanil group (7.58 ± 2.14) (P < 0.05). Conclusion: Combination of propofol and remifentanil significantly reduced the time taken for recovery, discharge and agitation level compared to propofol.

Protective effect of quercetin on alteration of antioxidant genes expression and histological changes in the dental pulp of the streptozotocin-diabetic rats.

OBJECTIVE: We aimed to assess the effect of quercetin as one of the most common polyphenols with anti-inflammatory and antioxidant properties on expression levels of catalase (CAT), superoxide dismutase 1 (SOD1), and glutathione peroxidase 1 (GPX1), involved in the detoxification of reactive oxygen species (ROS), and histology of dental pulp in streptozotocin-diabetic rats. DESIGN: Type 1 diabetes mellitus (T1DM) was induced by intraperitoneal injection of streptozotocin in adult male Wistar rats. Animals (n = 24) were equally distributed into control, diabetes, and diabetes treated with quercetin groups. Rats were gavaged daily with quercetin (25 mg/kg) for forty days. To measure the mRNA levels of antioxidant genes, quantitate real-time PCR was applied. The oxidative stress parameters such as total antioxidant capacity (TAC) and histopathological assessments were performed. RESULTS: A significant increase in the relative quantification mRNA levels of SOD1, CAT, GPX1 was detected in diabetic rat dental pulp. Besides, persistent hyperglycemia led to the enhancement of TAC level and degeneration of connective tissue of the dental pulp. Interestingly, quercetin normalized the expression mRNA levels of CAT, SOD1, GPX1 to near the normal level. Moreover, quercetin treatment normalized TAC levels. CONCLUSIONS: Because of the crucial role of antioxidants in diabetic complications, the findings of the current study presented a molecular basis for the protective effect of quercetin on dental pulp in diabetic conditions.

Bispectoral index scores of pediatric patients under dental treatment and recovery conditions: Study of children assigned for general anesthesia under propofol and isofloran regimes.

BACKGROUND: This study was planned to determine the relationship between bispectoral index (BIS) during dental treatment and recovery conditions in children undergoing two regimes of anesthesia of propofol and isoflurane. MATERIALS AND METHODS: In this single-blind clinical trial study, 57 4-7-year-old healthy children who had been referred for dental treatment under general anesthesia between 60 and 90 min were selected by convenience sampling and assigned to two groups, after obtaining their parents' written consent. The anesthesia was induced by inhalation. For the first group, the anesthesia was preserved by a mixture of oxygen (50%), nitrous oxide (50%), and isoflurane (1%). For the second group, the anesthesia was preserved by a mixture of oxygen (50%), nitrous oxide (50%), and propofol was administered intravenously at a dose of 100 Ng/kg/min. The patients' vital signs, BIS, and agitation scores were recorded every 10 min. The data were analyzed by repeated measure ANOVA and t-tests at a significance level of α = 0.05 using SPSS version 20. RESULTS: The results of independent t-test for anesthesia time showed no statistically significant difference between isoflurane and propofol (P = 0.87). Controlling age, the BIS difference between the two anesthetic agents was not significant (P > 0.05); however, it was negatively correlated with the duration of anesthesia and the discharge time (P = 0.001, r = -0.308) and (P < 0.001, r = -0.55). CONCLUSION: The same depth of anesthesia is produced by propofol and isoflurane, but lower recovery complications from anesthesia are observed with isoflurane.

PCL-forsterite nanocomposite fibrous membranes for controlled release of dexamethasone.

The well-known treatment of the alveolar bone defects is guided tissue regeneration (GTR). Engineered membranes combined with osteo-differentiation factors have been offered a promising strategy for GTR application. Recently, poly(ε-caprolactone) (PCL)-forsterite (PCL-F) nanocomposite fibrous membranes have been developed. However, PCL-F membranes could not promote bone tissue regeneration. The aim of this research is to encapsulate an osteogenic factor [dexamethasone (DEX)] in PCL-F membranes and evaluate the effects of forsterite nanopowder (particle size = 25-45 nm) and fiber organization on DEX delivery for GTR application. The hypothesis is that the release kinetic and profile of DEX could be controlled through variation of forsterite content (0, 5 and 10 wt%) and fiber arrangement (aligned and random). Results demonstrated while DEX release was sustained over a period of 4 weeks, its kinetic was governed by the membrane architecture and composition. For example, aligned PCL-F nanocomposite fibrous membrane consisting of 10 %(w/v) forsterite nanopowder exhibited the least initial burst release (13 % release in the first 12 h) and allowed sustained release of DEX. Additionally, forsterite nanopowder inclusion changed the kinetic of DEX release from Fickian diffusion to an anomalous transport. The bioactivity of released DEX was estimated using culturing the stem cells from human exfoliated deciduous teeth (SHED) on the membranes. Results demonstrated that proliferation and osteogenic differentiation of SHED could be governed by DEX release process. While DEX release from the membranes decreased SHED proliferation, stimulated the matrix mineralization. Our finding indicated that aligned PCL-F/DEX membrane could be used as a carrier for the sustained release of drugs relevant for GTR trophy.

General Dental Practitioners' Knowledge about the Emergency Management of Dental Trauma.

INTRODUCTION: The aim of this descriptive cross-sectional study was to assess the general dental practitioners (GDPs)'s knowledge regarding the emergency management of traumatic dental injuries (TDI) in Isfahan, Iran. METHODS AND MATERIALS: In this study a two-part questionnaire consisting of 14 questions was distributed among 241 GDPs. Part 1 included seven questions focusing on personal and professional information and part 2 asked questions about seven given cases of dental traumas. One score was dedicated to each correct answer; the total score of 0 to 4 was considered as poor knowledge, while scores 5-8, 9-11 and 12-14 were assigned as moderate, good and excellent knowledge, respectively. The data were analyzed using the Student's t-test and one-way ANOVA. Spearman's and Pearson's correlation coefficient were used to determine the associations between the emergency treatment knowledge and dentists' professional information. RESULTS: With regards to the level of GDP's knowledge, the mean score was 7.61±2.68 suggesting a moderate score; a total of 177 (73.2%) of the dentists showed a moderate level of knowledge. A significant association was found between the frequency of dental trauma cases that were encountered and treated by GDPs in their daily practice (P=0.004, r=0.2). CONCLUSION: The overall knowledge of GDPs about the emergency management of TDI in the selected community was moderate.

Transplantation of stem cells from human exfoliated deciduous teeth for bone regeneration in the dog mandibular defect.

AIM: To investigate the effect of stem cells from human exfoliated deciduous teeth (SHED) transplanted for bone regeneration in the dog mandibular defect. METHODS: In this prospective comparative study, SHEDs had been isolated 5 years ago from human exfoliated deciduous teeth. The undifferentiated stem cells were seeded into mandibular bone through-and-through defects of 4 dogs. Similar defects in control group were filled with cell-free collagen scaffold. After 12 wk, biopsies were taken and morphometric analysis was performed. The percentage of new bone formation and foreign body reaction were measured in each case. The data were subject to statistical analysis using the Mann-Whitney U and Kruskalwalis statistical tests. Differences at P < 0.05 was considered as significant level. RESULTS: There were no significant differences between control and SHED-seeded groups in connective tissue (P = 0.248), woven bone (P = 0.248) and compact bone (P = 0.082). There were not any side effects in transplanted SHED group such as teratoma or malignancy and abnormalities in this period. CONCLUSION: SHEDs which had been isolated and characterized 5 years ago and stored with cryopreservation banking were capable of proliferation and osteogenesis after 5 years, and no immune response was observed after three months of seeded SHEDs.

Messenger RNA Expression Patterns of Neurotrophins during Transdifferentiation of Stem Cells from Human-Exfoliated Deciduous Teeth into Neural-like Cells.

BACKGROUND: Stem cells from Human Exfoliated Deciduous teeth (SHED) have the capability to differentiate into neural cells. Neurotrophins including Nerve Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) have neurogenesis, neurotrophic, or neuroprotective effects and are expressed in developing teeth. The aim of this study was to measure quantitative changes in mRNA expression levels of neurotrophins in neural-like cells differentiated from dental pulp stem cells. METHODS: Isolated total RNA from SHED, dental pulp and neural-like cells (n = 3) were transcribed into cDNA. Then real time PCR was done. Expression levels of mRNA for NGF, BDNF, NT-3, and NT-4 genes were compared in these three cells. RESULTS: In neural like cells, BDNF mRNA increased (372.1±113.5) significantly (p < 0.01) after differentiation. NGF mRNA increased to more than 266 times the dental pulp level after differentiation. A similar pattern was seen for the expression of NT3 after differentiation. NT4 mRNA enhancement was 1344±630.8 and 30.7±7.9 fold in neural like cells and SHED cells, respectively. Results show alterations with different degrees and direction in neurotrophins mRNA expression levels in these cells. CONCLUSION: Our results suggest that neurotrophins dental pulp cells, SHED cells and neural like cells derived from SHED cells produce neurotrophic factors. Since the large amounts of neurotrophins are expressed in SHED and neural like cells they may have important role in survival and differentiation of dental pulp stem cells and obtained information may lead to a novel method for tooth regeneration.

Effect of phentolamine mesylate on duration of soft tissue local anesthesia in children.

OBJECTIVE: Addition of vasoconstrictors to local anesthesia results in prolonged pain control. However, associated soft-tissue anesthesia (STA) of the lips and tongue typically lasts 3-5 hours which is longer than required time for pain control after routine dental procedures can lead to inadvertent biting of the soft tissue, particularly in children. The present study aimed to evaluate phentolamine mesylate (PM) effect on duration of STA and incidence of soft-tissue trauma after mandibular block injection. METHODS: This randomized, double-blinded, controlled clinical trial included 54 patients with the age of 4-11 years. In group 1 at the first visit, the children received ordinary local anesthetic (LA) consisting of lidocaine 2% and epinephrine 1:80,000 and the PM injection was performed 30 minutes later. At the second visit, the contralateral side received LA injection then the dental procedure was done and a sham injection was performed. In group 2 at the first visit, patients received control injection and at the second visit received PM injection. Then the reversal time for normal sensation of soft tissue, the vital signs, and the incidence of soft-tissue trauma in a period of 3-5 hours after injection were evaluated. FINDINGS: There was a statistically significant difference (P < 0.001) in recovery time of normal lip sensation between case and control groups and also between two groups (P < 0.003). Incidence of soft-tissue trauma between case and control groups showed a statistically significant difference (P < 0.039). CONCLUSION: PM can be considered as a safe and effective drug for reduction of reversal time of STA after dental procedures.

Induced in vitro differentiation of neural-like cells from human exfoliated deciduous teeth-derived stem cells.

Stem cells from human exfoliated deciduous teeth (SHED) are highly proliferative, clonogenic and multipotent stem cells with a neural crest cell origin. Additionally, they can be collected with minimal invasiveness in comparison with other sources of mesenchymal stem cells (MSCs). Therefore, SHED could be a desirable option for potential therapeutic applications. In this study, SHEDs were established from enzyme-disaggregated deciduous dental pulp obtained from 6 to 9 year-old children. The cells had typical fibroblastoid morphology and expressed antigens characteristic of MSCs, STRO1, CD146, CD45, CD90, CD106 and CD166, but not the hematopoietic and endothelial markers, CD34 and CD31, as assessed by FACS analysis. Differentiation assessment revealed a strong osteogenic and adipogenic potential of SHEDs. In order to further evaluate the in vitro differentiation potential of SHED into neural cells, a simple short time growth factor-mediated induction was used. Immunofluorescence staining and flow cytometric analysis revealed that SHED rapidly expressed nestin and b-III tubulin, and later expressed intermediate neural markers. In addition, the intensity and percentages of nestin and b-III tubulin and mature neural markers (PSA-NCAM, NeuN, Tau, TH, or GFAP) increased significantly following treatment. Moreover, RT-PCR and Western blot analyses showed that the neural markers were strongly up-regulated after induction. In conclusion, these results provide evidence that SHED can differentiate into neural cells by the expression of a comprehensive set of genes and proteins that define neural-like cells in vitro. SHED cells might be considered as new candidates for the autologous transplantation of a wide variety of neurological diseases and neurotraumatic injuries.