Enhancement of acellular biomineralization, dental pulp stem cell migration, and differentiation by hybrid fibrin gelatin scaffolds.

OBJECTIVE: The current in vitro study aims to evaluate cross-linked hydrogels with and without the addition of fibrin that could potentially be used in endodontic regeneration as a scaffold material. METHODS: Synthesis of gelatin/fibrin scaffold, and performing nanoscale characterization using cryo-electron microscopy, dynamic rheology, and XRF for structure property relations; plating dental pulp stem cells and determining mineralization, migration, and differentiation using rt-PCR, XRF, and Raman spectroscopy. RESULTS: Cryo electron imaging shows gelatin and fibrin, when gelled separately to form classical rectangular cross-linked networks, where the modulus scales inversely with the cube root of the mesh size. When gelled together, a network with a fundamentally different structure is formed, which has higher ductility and when placed as a scaffold in osteogenic media, produces twice the mineral content. Immunofluorescence, RT-PCR and Rahman Spectroscopy indicate that the hybrid gel enhances cell migration, induces odontogenic differentiation of dental pulp stem cells, and promotes formation of dentin. SIGNIFICANCE: The mechanical properties of the hybrid gel scaffold enhance in-migration of stem cells and subsequent differentiation, which are critical for regenerative procedures. Under acellular conditions, placement of the hybrid gel enhances biomineralization, which would strengthen the root if used as a scaffold for endodontic regeneration. Our in vitro findings are consistent with previous in vivo studies which show improved mineralization when bleeding is induced into the canal, given that fibrin is a primary component in blood clotting. Therefore, insertion of the hybrid gelatin-fibrin scaffold could enable more reproducible and consistent outcomes if used for regenerative endodontic treatment (RET).

Non-cytotoxic Root Canal Dressing with Improved Antimicrobial Efficacy.

INTRODUCTION: Recurrent endodontic infections are primarily caused by Enterococcus faecalis and are more challenging to treat, compared with primary infection of the root canal system. Calcium hydroxide (CH) is used as an interappointment dressing in endodontics despite its inefficacy against E. faecalis and other pathogens. To improve antimicrobial properties and limit cytotoxicity of CH, we added salicylic acid to CH (CASA) to disinfect the canal. CASA overcomes the main pathogen responsible for recurrent endodontic infections. The aim of this study was to evaluate the antimicrobial activity of CASA and its cytotoxicity against dental pulp stem cells (DPSCs) and its effect on the differentiation potential of DPSCs. METHODS: Mature E. faecalis biofilm cultured on dentin chips was exposed to CASA and studied using confocal laser scanning microscopy. The dose-dependency of CASA was also studied using the liquid suspension test. The cytotoxicity was tested against DPSCs, and its effect on the expression of osteocalcin and alkaline phosphatase was studied. RESULTS: CASA produced larger zones of inhibition than CH for all species tested and demonstrated superior efficacy than CH against E. faecalis biofilm. Cytotoxicity studies indicated DPSC's high tolerance for CASA; addition of CASA to DPSCs was observed to increase the expression of biological markers related to mineralization. CONCLUSIONS: CASA was proved to have superior antibacterial efficacy against E. faecalis when compared with CH. It also increased the expression of some DPSC differentiation markers involved in mineralization.

Efficacy of hypochlorous acid (HOCl) fog in sanitizing surfaces against Enterococcus faecalis.

BACKGROUND: Fogging is an efficient method when disinfection of large areas is desired. METHODS: Two methods of ultrasonic fogging, pulsed and continuous, were compared on bacteria dried on either aluminum or polystyrene surfaces. We characterized commercial and home-made hypochlorous acid (HOCl) with respect to storage and means of production. RESULTS: We found that the initial chlorine concentration of the commercial solution was approximately 550 ppm, and when stored open under ambient conditions, the chlorine content decreased at a rate of 30% every 100 days. The HOCl produced using the home synthesizers had a maximum chlorine content of 257.6 ppm which decayed by 65% after 100 days. A second synthesizer produced a liquid with high chlorine content and pH, 750ppm and pH = 8.55. The anti-bacterial efficacy was probed using Enterococcus faecalis, a persistent source of infection in public and clinical spaces. Time course studies determined that E. faecalis could survive dry on surfaces for more than 12 weeks, but was easily eliminated in half the fogging time. CONCLUSIONS: The most effective mode of application was determined to be continuous fogging where a 6.59 log reduction was established in vertical geometry. The optimal pulsed fogging protocol produced a similar reduction, but required nearly 5 times as long. The home synthesized versions yielded much lower log bacterial reductions. No significant differences in outcome were determined between polymer or metal surfaces.

Regenerative Endodontic Treatment as a Biologically Based Approach for Non-Surgical Retreatment of Immature Teeth.

INTRODUCTION: The goal of regenerative endodontic treatment (RET) is to regenerate the pulp-dentin complex in immature teeth with pulp necrosis. There is no consensus in using RET in previously treated teeth. This article reports on long-term outcomes of RET in previously treated immature teeth. METHODS: Previously treated immature teeth with signs/symptoms of failure were included. After local anesthesia and rubber dam isolation, the root canal filling material was removed without the use of chemical solvents. The root canals were irrigated with 6% sodium hypochlorite using an EndoVac (Kerr Endodontics, Culver City, CA), and a creamy mix of metronidazole and ciprofloxacin was placed in the canals for 4 weeks. At the second visit, the antibiotic dressing was removed using 17% EDTA. Bleeding was induced into the root canal space, and SynOss Putty (Collagen Matrix Inc, Oakland, NJ) was placed. Bioceramic putty was placed over the SynOss Putty, and the teeth were restored at a subsequent visit. RESULTS: Five teeth in 4 patients were included. The patients' ages ranged from 14-46 years. Recall examinations were performed from 20 to 72 months with an average of 54.4 months. The apical openings of the teeth ranged from 1-3.7 mm. All teeth were functional and asymptomatic at the recall visits. All periapical lesions resolved with partial or complete mineralization of the root canals, and all teeth showed partial to complete apical closure at the follow-up visits. CONCLUSIONS: RET can be a viable option for nonsurgical retreatment of immature teeth. This article adds a new perspective to the field of regenerative endodontics.

Revitalization of open apex teeth with apical periodontitis using a collagen-hydroxyapatite scaffold.

An enhanced revision of the revitalization endodontic technique for immature teeth with apical periodontitis has been described. It includes the addition of collagen-hydroxyapatite scaffold to the currently practiced revascularization technique. Four cases treated in series are presented in this report, 1 case involving 2 teeth. Periapical diagnoses of immature teeth included "asymptomatic apical periodontitis," "symptomatic apical periodontitis," and "acute apical abscess." Additionally, 1 fully developed tooth that had undergone root canal treatment that failed had a periapical diagnosis of acute apical abscess. An established revascularization protocol was used for all teeth. In addition to stimulating blood clots, all teeth were filled with collagen-hydroxyapatite scaffolds. Periapical radiolucencies healed in all teeth, and diffuse radiopacity developed within the coronal portions of canal spaces. Root development with root lengthening occurred in the immature nonvital maxillary premolar that had not undergone prior treatment. The technique of adding a collagen-hydroxyapatite scaffold to the existing revitalization protocol has been described in which substantial hard tissue repair has occurred. This may leave teeth more fully developed and less likely to fracture.

Evaluation of odontogenic maxillary sinusitis using cone-beam computed tomography: three case reports.

INTRODUCTION: Ten to twelve percent of all cases of maxillary sinusitis derive from odontogenic origin. The purpose of this study was to report the use of cone-beam computed tomography (CBCT) scanning in elucidating dental pathology as an etiology of maxillary sinusitis. METHODS: Intraoral periapical radiographs and CBCT scanning were performed in the evaluation of three patients presenting with pain, sinus congestion, or respiratory complaints. In the first case, extractions of impacted third molar and adjacent nonrestorable tooth were performed. In the second two cases, endodontic therapy was done. Radiologic follow-up with CBCT scanning or medical computed tomography scanning was performed 6 to 12 months after dental procedures were performed. RESULTS: All three patients presented with severe sinusitis that resolved after appropriate dental treatment. The first patient also showed marked improvement of chronic bronchitis after completion of dental treatment. In all patients, complete or near total resolution of sinusitis, including eradication of mucous retention cyst, was confirmed by post-treatment CBCT or computed tomography scanning. CONCLUSIONS: These cases show the utility of CBCT scanning in evaluating patients presenting with concurrent sinus and dental complaints. In these three patients, maxillary sinusitis of odontogenic origin responded well to the eradication of dental etiology.