A Novel Diagnostic and Treatment Approach to an Unusual Case of Dens Invaginatus in a Mandibular Lateral Incisor Using CBCT and 3D Printing Technology.

BACKGROUND: This case report demonstrates the use of three-dimensional (3D) models produced from a cone beam computed tomographic (CBCT) volume to develop a treatment strategy for a rare type of dens invaginatus (DI) in a mandibular incisor. METHODS: A patient with DI Type IIIa presented for endodontic treatment. Following CBCT evaluation, the complex morphologic nature of the invagination required additional diagnostic tools for treatment planning. The fabrication of 3D models provided clarity regarding the treatment strategy. Treatment involved intracanal medication with calcium hydroxide Ca(OH)2, nonsurgical root canal therapy (NS-RCT) of the main canal, and endodontic surgery for the DI anomaly using mineral trioxide aggregate (MTA), bone graft, and platelet-rich fibrin (PRF) membrane. RESULTS: The use of 3D models provided an invaluable guide for proper treatment. Complicating factors were diagnosed and planned for accordingly. CONCLUSIONS: It is difficult to appreciate the anatomical complexity, the extent, and the nature of the invagination of rare Type III DI morphology. CBCT imaging and 3D models played a critical role in the pre-treatment planning to ensure a predictable outcome. A 3D model is recommended as a diagnostic tool in treating complex cases where the DI morphology is wide, oblique, or the foraminal opening is irregular.

A Potential Intracanal Medicament, 2-Hydroxyisocaproic Acid (HICA): Cytotoxicity, Genotoxicity, and Its Effect on SCAP Differentiation.

Intracanal medicaments with maximal antimicrobial efficacy and minimal damage to resident stem cells are essential for successful regenerative endodontic procedures. 2-Hydroxyisocaproic acid (HICA) could have the attributes of a potential intracanal medicament. This study evaluates its cytotoxicity, genotoxicity, and effects on the odontogenic and osteogenic differentiation of the stem cells of the apical papilla (SCAP). Cytotoxicity and cell viability assays were performed on cells treated for 24, 48, and 72 h with varying concentrations of HICA and compared to the standard intracanal medicament, calcium hydroxide. The genotoxicity was assessed via immunofluorescence for two markers of DNA double-strand breaks: phosphorylated γH2AX and 53BP1. The SCAP differentiation was evaluated based on the alkaline phosphatase activity, Alizarin Red staining, and expression of odontogenic and osteogenic genes (DSPP1, BSP1, OCN, RUNX2) in the presence of selected HICA concentrations. HICA was not cytotoxic at concentrations up to 10 mg/mL, regardless of the exposure time, although it was cytostatic at all tested concentrations. HICA was not genotoxic at concentrations below 5 mg/mL. No difference in cytotoxicity or genotoxicity was found between HICA and calcium hydroxide at 1 mg/mL. HICA retained about 70% of the osteogenic differentiation potential at 1 mg/mL. Within the limitations of this in vitro study, we show that HICA at 1 mg/mL could be a potential intracanal medicament for REPs.

Growth Factors Released from Advanced Platelet-Rich Fibrin in the Presence of Calcium-Based Silicate Materials and Their Impact on the Viability and Migration of Stem Cells of Apical Papilla.

Advanced platelet-rich fibrin (A-PRF) provides the scaffold and growth factors necessary for stem cells to proliferate and differentiate in successful regenerative endodontic procedures. This study investigates the release of transforming growth factor-ß1 (TGF-ß1), platelet-derived growth factor (PDGF), and vascular endothelial growth factor (VEGF) from A-PRF in cell culture media in the presence and absence of mineral trioxide aggregate (MTA) or Biodentine. Additionally, this research assesses the viability and migration of stem cells of the apical papilla (SCAP) in previously conditioned media. A-PRF obtained from 14 participants were incubated for 7 days in cell culture media alone or via layering with MTA or Biodentine discs and the release of selected growth factors in the media was evaluated using ELISA. The viability of SCAP grown in conditioned media was measured using the CCK8 assay, while SCAP migration was assessed via a transwell assay by counting migrated cells. The release of TGF-ß1, PDGF, and VEGF was significantly higher in media with A-PRF alone than in the presence of either calcium-based silicate material (p < 0.05), which showed no difference from the no-A-PRF control (p < 0.05). None of the tested growth factors released in the A-PRF-conditioned media correlated with clot weight. A-PRF-conditioned media, both with and without calcium-based silicate materials, did not impact SCAP viability and migration (p > 0.05). This study shows that SCAP behavior is not impacted by the decrease in growth factor released in the presence of calcium-based silicate materials and that their role in REPs warrants further investigation.

Volumetric Evaluation of 5 Root Canal Obturation Methods in TrueTooth 3-dimensional-Printed Tooth Replicas Using Nano-computed Tomography.

INTRODUCTION: The aim of this study was to evaluate the volumes of total obturation and voids in different obturation techniques using nano-computed tomographic imaging. The null hypothesis was that the obturation technique and the materials used have no effect on the total volume of obturation or the total volume of voids. METHODS: Fifty maxillary left central incisor 3-dimensional-printed replicas (TrueTooth; Dental Engineering Laboratories, Santa Barbara, CA) were instrumented and randomly assigned to 5 different obturation groups (n = 10): single cone with EndoSequence Gutta-Percha Points (Brasseler USA, Savannah, GA) and Ribbon Sealer (Dentsply Sirona, Tulsa, OK) (SC1), single cone with BC 150 Series Gutta-Percha Points (Brasseler USA) and EndoSequence BC Sealer (Brasseler USA) (SC2), continuous wave with EndoSequence Gutta-Percha Points and Ribbon Sealer (CW), GuttaCore carrier obturation (Dentsply Sirona) and Ribbon Sealer (GC), and cold lateral condensation with EndoSequence Gutta-Percha Points and Ribbon Sealer (CL). After obturation, nano-computed tomographic images were obtained, and volumetric analysis was performed. Statistical analysis using 1-way analysis of variance (ANOVA). The level of significance was set at 5% (P < .05). RESULTS: The 1-way ANOVA for total obturation indicated a statistically significant effect of group on obturation. Post hoc tests revealed a significant difference between the SC2, CW, and CL groups compared with the SC1 and GC groups. The 1-way ANOVA for calculated voids indicated a statistically significant effect of group on voids. Post hoc tests revealed significant differences between the SC1 group and the GC and CL groups. CONCLUSIONS: This study concluded that obturation technique and the materials used significantly affect the total volume of obturation material and potential for voids.

Evaluation of Cannabinoids on the Odonto/Osteogenesis in Human Dental Pulp Cells In Vitro.

INTRODUCTION: Cannabinoids possess anti-inflammatory, analgesic, and osteogenic effects in different cell types and tissues. The null hypothesis is delta-9-tetrahydrocannabinol (THC) might induce dental tissue repair and regeneration. The aim of this study was to investigate the effect of THC on human dental pulp cell (HDPC) viability and biomineralization as well as the molecular mechanism of THC-induced odonto/osteogenic differentiation of HDPCs. METHODS: The toxicity of THC on HDPCs was determined by 3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide assay. The odonto/osteogenic differentiation marker genes of HDPCs were assessed by real-time polymerase chain reaction with or without THC treatment. HDPC biomineralization was examined by collagen synthesis and calcium nodule deposition. The molecular mechanism of THC on HDPCs was investigated by examining the mitogen-activated protein kinase (MAPK) signaling pathway via blocking cannabinoid receptor type 1 or 2 receptors. RESULTS: We found that THC had no inhibition of HDPC vitality in the testing concentration (0-100 µmol/L). THC showed biphasic effects on HDPC proliferation. At a low dose (<5 µmol/L), THC considerably increased HDPC cell division. HDPC proliferation reduced with higher THC concentrations (>5 µmol/L). The expression of odonto/osteogenic marker genes were up-regulated in the presence of cannabinoids. These were confirmed by increased collagen synthesis and mineralized calcium nodule formation in the cannabinoid group. The effect of THC-induced odonto/osteogenesis occurred via MAPK signaling. CONCLUSIONS: THC was biocompatible to HDPCs by promoting their mitogenic division in a biphasic pattern depending on the concentration. THC induced HDPC odonto/osteogenic differentiation through the activation of MAPK mediated by CB1 and CB2 receptors. Cannabinoids may play an important role in the HDPC regeneration process and potentially be used as a pulp-capping agent.

Micro-computed Tomographic Evaluation of the Shaping Ability of WaveOne Gold, TRUShape, EdgeCoil, and XP-3D Shaper Endodontic Files in Single, Oval-shaped Canals: An In Vitro Study.

INTRODUCTION: This study evaluated and compared the shaping ability of the WaveOne Gold (Dentsply/Tulsa Dental Specialties, Tulsa, OK), TRUShape 3D Conforming File (Dentsply/Tulsa Dental Specialties), EdgeCoil (EdgeEndo, Albuquerque, NM), and XP-3D Shaper (Brasseler USA, Savannah, GA) endodontic file systems on oval-shaped canals using micro-computed tomographic (micro-CT) technology. METHODS: Thirty-two oval-shaped, single-canal extracted human teeth were decoronated 1 mm coronal to the cementoenamel junction and scanned via a micro-CT scanner (µCT100; Scanco Medical, Bassersdorf, Switzerland). Teeth were divided into 4 groups (n = 8) and instrumented according to the manufacturer's instructions. Coregistered images, before and after root canal preparation, were evaluated for morphometric measurements of the surface area, volume, structure model index (SMI), conicity, and percent of walls untouched using the manufacturer's evaluation software (IPL Register, Scanco Medical). Data were statistically compared between groups using 1-way analysis of variance and within groups using a paired sample t test. RESULTS: Instrumentation with all file types increased the surface area, volume, and conicity between and within groups. There was no statistically significant difference between the groups for any of the rotary instruments used (P < .05). CONCLUSIONS: Instrumentation of oval-shaped canals with WaveOne Gold, TRUShape, EdgeCoil, and XP-3D Shaper rotary endodontic instruments similarly increase the volume, surface area, and conicity. None of the file systems were capable of contacting all of the surface area in any canal.

Cytotoxicity and Genotoxicity of a New Intracanal Medicament, 2-hydroxyisocaproic Acid-An In Vitro Study.

INTRODUCTION: A successful outcome of root canal therapy relies on effective disinfection of the root canal system, including the use of intracanal medicaments, which vary in their bactericidal and cytotoxic properties. Assessing the benefits and risks associated with the use of these medicaments is of extreme importance, especially in regenerative endodontic procedures, because residual stem cells may be harmed. In this study, we tested the cytotoxicity and genotoxicity of a novel agent, 2-hydroxyisocaproic acid (HICA), and compared its properties with those of a well-established medicament, calcium hydroxide. METHODS: Human periodontal ligament fibroblasts were exposed to varying concentrations of HICA (1, 2.5, 5, 10, 20, and 40 mg/mL) for 24 hours, and a dose-response curve was generated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Immunofluorescence for 2 markers of DNA double-strand breaks, phosphorylated γH2AX and 53BP1, was used to establish the genotoxicity of HICA at various half maximal effective concentration (EC50) fractions. Cytotoxicity and genotoxicity of HICA and calcium hydroxide at 1 mg/mL were compared at 24 and 48 hours using the same methods. RESULTS: At 10 mg/mL and higher, HICA was significantly more cytotoxic and genotoxic than the control (P < .05 and P < .0001, respectively). Calcium hydroxide at 1 mg/mL was more cytotoxic than HICA at 1 mg/mL at 24 and 48 hours (P < .05 for both), whereas no difference in the accumulated DNA damage was observed. CONCLUSIONS: HICA is not cytotoxic and genotoxic at concentrations <10 mg/mL. At the concentration of 1 mg/mL, HICA is significantly less cytotoxic than calcium hydroxide.

The Effect of Temperature on Cyclic Fatigue of Nickel-titanium Rotary Endodontic Instruments.

INTRODUCTION: This study examined the effect of different temperatures on the cyclic fatigue of nickel-titanium rotary files. METHODS: Three groups of nickel-titanium rotary files (EF group [EdgeFile; EdgeEndo, Albuquerque, NM], VB group [Vortex Blue; Dentsply Tulsa Dental Specialties, Tulsa, OK], and ESX group [ESX; Brasseler USA, Savannah, GA]) of size 25 with a .04 taper and 25-mm length were tested in a metal block that simulated a canal curvature of 60° and a 5-mm radius curvature. The block was submerged in a water bath filled with water at 3°C, 22°C, 37°C, and 60°C. At each temperature, 30 files from each group were rotated at 500 rpm in the block. The number of cycles to fracture (NCF) was calculated. Statistical analysis was completed using a 1-way analysis of variance with significance at P < .05. RESULTS: VB group showed a significant decrease in NCF as the temperature increased from 3°C to 60°C. The ESX group showed a significant decrease in NCF as the temperature increased from 3°C to 37°C. The EF group showed a significant increase in NCF from 3°C to 22°C and a significant decrease in NCF from 22°C to 37°C. For each temperature, the EF group showed higher NCF than the VB group, which showed higher NCF than the ESX group. CONCLUSIONS: In this in vitro study, temperature was found to significantly affect the cyclic fatigue of nickel-titanium rotary files. At each tested temperature, NCF was the highest for the EF group followed by the VB group and lowest for the ESX group. Future cyclic fatigue studies should be conducted at body temperature.