Bacterial sealing ability of calcium silicate-based sealer for endodontic surgery: an in-vitro study.

BACKGROUND: Apical surgery with standard retrograde maneuvers may be challenging in certain cases. Simplifying apical surgery to reduce operating time and streamline retrograde manipulation is an emerging need in clinical endodontics. AIM OF THE STUDY: The aim of the study was to compare the bacterial sealing ability of a calcium silicate-based sealer with the single cone technique combined with root end resection only, and calcium silicate-based sealer as a retrograde filling versus MTA retrofilling, and to analyze bacterial viability using confocal laser scanning microscope (CLSM). MATERIALS AND METHODS: In this in vitro experimental study, 50 extracted human maxillary incisor teeth were instrumented and randomly divided into five groups: three experimental groups, a positive control group, and a negative control group (n = 10/group). In the experimental groups, the roots were obturated using the single cone technique (SCT) and a calcium silicate-based sealer. In group 1, the roots were resected 3 mm from the apex with no further retrograde preparation or filling. In groups 2 and 3, the roots were resected, retroprepared, and retrofilled with either a calcium silicate-based sealer or MTA, respectively. Group 4 (positive control) was filled with a single gutta-percha cone without any sealer. In group 5 (negative control), the canals were left empty, and the roots were sealed with wax and nail varnish. A bacterial leakage model using Enterococcus faecalis was employed to assess the sealing ability over a 30-day period, checking for turbidity and analyzing colony forming units (CFUs) per milliliter. Five specimens from each group were examined using CLSM for bacterial viability. Data for the bacterial sealing ability were statistically analyzed using chi-squared and Kruskal-Wallis tests. RESULTS: The three experimental groups did not show significant differences in terms of bacterial leakage, or bacterial counts (CFUs) (P > 0.05). However, significant differences were observed when comparing the experimental groups to the positive control group. Notably, the calcium silicate-based sealer, when used as a retrofilling, yielded the best sealing ability. CLSM imaging revealed viable bacterial penetration in all the positive control group specimens while for the experimental groups, dead bacteria was the prominent feature seen. CONCLUSION: Within the limitations of this study, it could be concluded that the bacterial sealing ability of calcium silicate-based sealer with the single cone technique combined with root end resection only and calcium silicate-based sealer as a retrograde filling were comparable with MTA retrofilling during endodontic surgical procedures.

Antibacterial effectiveness of multi-strain probiotics supernatants intracanal medication on Enterococcus faecalis biofilm in a tooth model.

BACKGROUND: To assess the antibacterial activity of multi-strain probiotics supernatants (MSP); Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus acidophilus as an intracanal medication on Enterococcus faecalis (E. faecalis) biofilm in a tooth model. METHODS: Sixty extracted human single-rooted teeth with single canals were instrumented, sterilized, and inoculated with E. faecalis. After 21 days of incubation, four specimens were randomly selected to validate the biofilm formation by scanning electron microscope (SEM). The remaining specimens were randomly divided (n = 14), according to the intracanal medication (ICM) received into: Ca(OH)2: calcium hydroxide paste (35% Ultra Cal XS Ca(OH)2), Probiotics supernatants: MSP in poloxamer gel vehicle Poloxamer: poloxamer gel vehicle and, Control: E. faecalis biofilm only. The tested groups were further subdivided into two equal subgroups (n = 7) according to the incubation period (24 h and 7 days). Shaved dentin chips were obtained and collected by H-files and paper points, respectively for bacterial culture. The antibacterial activity was assessed after each incubation period quantitatively and qualitatively using bacterial colony-forming units per milliliter (CFUs/ml) and SEM, respectively. RESULTS: The lowest CFUs/ml was found in Ca (OH)2 with a significant difference compared to other groups after 24 h. After 7 days, a similar outcome was found with a further significant reduction of CFUs/ml in all groups with no statistical difference between Ca(OH)2 and probiotics supernatants groups. Ca (OH)2 and Probiotics supernatants groups showed a significant (p < 0.05) percentage of overall bacterial reduction (100.00 ± 0.00% and 70.30 ± 12.95%, respectively) compared to poloxamer and control groups (27.80 ± 14.45 and 28.29 ± 19.79). SEM images showed a bacteria-free state in the Ca(OH)2 group after 7 days while few bacteria were found in the probiotics supernatants group. An extensive invasion of bacteria was found in poloxamer and controls groups. CONCLUSION: MSP has a potential antibacterial effect on E. faecalis growth closely similar to the routinely used Ca (OH)2.

Investigating the residual effect of silver nanoparticles gel as an intra-canal medicament on dental pulp stromal cells.

BACKGROUND: The aim of this study was to evaluate the indirect effects of residual silver nanoparticles (AgNPs) gel on human dental pulp stromal cells (DPSCs). METHODS: Ninety-five dentin discs (4x4x1 mm) were prepared from freshly extracted human single-rooted teeth following institutional ethical approval and informed consent. Samples were cleaned, autoclaved, and treated with: 1.5%NaOCl, Saline and 17% EDTA then randomly assigned to 5 groups that received 50 µl of one of the following treatments: 0.01%AgNPs, 0.015%AgNPs, 0.02%AgNPs, Calcium hydroxide (Ca (OH)2) or no treatment for 1 week. Discs were washed with Saline and 17%EDTA then seeded with DPSCs and incubated for 3 and 7 days. At 24 hours unattached cells were collected and counted. At each time point cytotoxicity (LDH assay), cell viability (live/dead staining and confocal microscopy) and cell proliferation (WST1 assay) were assessed. All experiments were repeated a minimum of 3 times using DPSCs isolated from 3 different donors for each time point assessed (n = 9/group). Statistical analysis was done using One-Way ANOVA followed by Tukey's test and Kruskal Wallis followed by post-hoc comparisons with significance set at p ≤ 0.05. RESULTS: After 24 hours, the percentage of DPSCs attachment ranged between 92.66% ±4.54 and 95.08% ±1.44 with no significant difference between groups (P = 0.126). Cell viability was ≥92% at 24 hours for all groups. However this percentage dropped to less than 60% at 3 days then started to rise again at 7 days. There was no significant difference in cytotoxicity between different groups at all time points except for 0.01%AgNPs group which had the highest cytotoxicity. DPSCs proliferation increased significantly from 3 to 7 days in all groups except for Ca (OH)2 which showed lower proliferation rates at both 3 (45.89%) and 7 days (79.25%). CONCLUSION: Dentin discs treated for 7 days with concentrations of AgNPs gel (0.01-0.02%) allowed more than 90% DPSCs cell attachment after 24 hours. The cytotoxicity and proliferation of DPSCs in response to AgNPs gel were comparable to those with calcium hydroxide. This suggests that AgNPs gel may represent a promising future candidate for clinical use in regenerative endodontics. However, its effects may be concentration-dependent warranting further investigation.

Evaluation of the antibacterial activity of Lactobacilli probiotics supernatants against Enterococcus faecalis (in-vitro study).

BACKGROUND: There is an increasing demand to find a potent antibacterial agent against endodontic pathogens with the least toxic effect. The study aimed to evaluate the antibacterial activity of Lactobacilli probiotics on Enterococcus faecalis (E. faecalis) in comparison to calcium hydroxide paste. METHODS: The study involved two stages; (stage one): determination of the antibacterial properties of three strains of Lactobacilli probiotics supernatants (PS); Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus acidophilus, and a cocktail mix of the three supernatants against E. faecalis using agar well diffusion method in both solution and gel phase. The formed zones of inhibition (ZOI) were measured in millimeters (mm) and compared to each other. PS solution and gel of the largest ZOI were further compared with calcium hydroxide paste (35% Ultra Cal XS Ca(OH)2) This was followed by (stage two): assessment of the minimum inhibitory concentration (MIC) of the PS that showed the largest ZOI against E. faecalis by agar well diffusion assay for both PS solution and gel. RESULTS: All supernatants showed growth inhibition against E. faecalis, and the cocktail mix showed the largest ZOI. However, no significant difference was found between the supernatants in both the solution and gel phases (p > 0.05). Ca(OH)2 showed a significantly lower effect than both the cocktail mix solution and gel (p < 0.05). The MIC of the cocktail mix solution and gel against E. faecalis was 50 mg/ml. (p > 0.05). CONCLUSION: PS has an antibacterial effect on E. faecalis and was more effective than Ca(OH)2. Lactobacilli probiotics could be a promising antibacterial agent used as an irrigant or an intracanal medication.

Human Treated Dentin Matrix Hydrogel as a Drug Delivery Scaffold for Regenerative Endodontics.

Introduction: The objective of the current study was to develop a human treated dentin matrix (hTDM) hydrogel for use as a scaffold to allow the controlled release of an antimicrobial agent for regenerative endodontics. Materials and Methods: Human extracted teeth were treated via chemical demineralization using ethylene diamine tetra-acetic acid solution to produce hTDM powder. Fourier transform infrared spectroscopy (FTIR) was conducted to determine the functional groups of hTDM, scanning electron microscopy (SEM) was used to define the morphology/particle size of hTDM, and energy dispersive X-ray analysis was performed to identify the superficial apatite groups. Prepared hTDM powder was added to the amoxicillin-clavulanate mixture with a mass ratio of 1:1. Then, the combination was dripped into a 5% (w/v) calcium chloride solution. Antibiotic release profiles were evaluated for 14 days via high performance liquid chromatography (HPLC). Hydrogel degradation properties were studied for 14 days using 10 mL of phosphate buffered saline (PBS). Encapsulation efficiency was determined by HPLC, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of amoxicillin-clavulanate were determined against Enterococcus faecalis (E. faecalis). The antibacterial activity of amoxicillin-clavulanate against E. faecalis was investigated for 14 days via agar diffusion test. Statistical analysis was performed with the Shapiro-Wilk test (P=0.05). Results: hTDM showed statistically a significant difference for percentage weight change (P=0.1). The encapsulation efficiencies for hTDM hydrogel with antibiotic and hydrogel with antibiotic was 96.08%±0.02 and 94.62%±0.11, respectively. MIC and MBC values of amoxicillin-clavulanate against E. faecalis were 2.4 µg/mL and 9.6 µg/mL, respectively. The antibacterial activity of antibiotic loaded hTDM hydrogels was significantly greater than loaded hydrogels alone by 31% after 4 days and 100% at 14 days, respectively (P≤0.001). Conclusions: This in vitro study showed antibiotic-loaded injectable hTDM hydrogel could be an alternative system to transfer antibiotic-based intracanal medicaments for use in regenerative endodontics.

Effect of phytic acid and ethylenediaminetetraacetic acid on penetration depth of bioceramic and resin sealers.

This study assessed influence of 1% phytic acid and 17% ethylenediaminetetraacetic acid (EDTA) on the dentinal tubules penetration of EndoSequence BC bioceramic-based and AH Plus resin-based sealers using confocal laser scanning microscopy (CLSM). Forty single-rooted mandibular premolars were divided randomly into four groups (n = 10). Group 1 received final irrigation with 1% phytic acid solution and canals sealed by AH Plus sealer, Group 2: 1% phytic acid solution and EndoSequence BC sealer, Group 3: 17% EDTA solution and AH Plus sealer and Group 4: 17% EDTA solution and EndoSequence BC sealer. Specimens were horizontally sectioned 2, 4 and 6 mm from the apex. Average maximum depth of sealer penetration was examined using CLSM. Group three showed the deepest sealer penetration at all three levels which was significantly higher than all other groups (P ˂ 0.05). Deep sealer penetration is achievable with AH Plus and EDTA. Phytic acid groups have moderate tubular penetration ability.

Evaluation of the Efficacy of Three Antimicrobial Agents Used for Regenerative Endodontics: An In Vitro Study.

Aim: To evaluate the antibacterial efficacy of double antibiotic paste (DAP), silver nanoparticle (AgNP) gel, and tailored amorphous multiporous bioactive glass (TAMP-BG) in concentrations suitable for regenerative endodontics (RE) against 3-week-old Enterococcus faecalis biofilms after 24 hours and 7 days. Results: Radicular human dentin specimens were prepared and inoculated with E. faecalis to form 3-week-old biofilms. DAP (1 mg/mL), AgNPs 0.02%, and TAMP-BG 100 mg/mL, in methylcellulose gel formulations, were used as antimicrobials. The biofilm disruption assay was done followed by quantification of bacterial colony-forming units and scanning electron microscopic analysis. Results showed that 1 mg/mL of DAP or AgNPs 0.02% provided significant antibiofilm effects at both time intervals. Both DAP and AgNPs significantly reduced bacterial counts and biofilms after 7 days compared with 24 hours. Furthermore, 100 mg/mL of TAMP-BG had a comparable antibiofilm effect, but it was less potent than DAP and AgNPs at both time intervals. Conclusions: DAP (1 mg/mL), 0.02% AgNPs, and TAMP-BG (100 mg/mL) can significantly reduce E. faecalis biofilms. However, complete elimination was only possible with DAP and AgNPs.

Histological observations of pulpal replacement tissue in immature dog teeth after revascularization of infected pulps.

BACKGROUND AND AIM: Many studies have examined the nature of tissue formed in the canals of immature necrotic teeth, following revascularization in animals and humans. While speculations have been made that regeneration of the pulp tissue might take place in the canal, the tissue has been found to be cementum-like, bone-like, and periodontal ligament-like. The purpose of this study was to histologically examine the tissue in the root canals in immature dog teeth that had been artificially infected and then revascularized. METHODS: Two 4- to 5-month-old mongrel dogs with immature teeth were used in the study. In one dog, four maxillary and four mandibular anterior teeth, and in another dog, four maxillary and five mandibular anterior teeth were used in the experiment. Pulp infection was artificially induced in the immature teeth. Revascularization was performed on all teeth by disinfecting the root canals with sodium hypochlorite irrigation and triple antibiotic intracanal dressing, completed with induction of intracanal bleeding, and sealed with an MTA plug. The access cavity was restored with silver amalgam. The animals were sacrificed 3 months after revascularization procedures. The revascularized teeth and surrounding periodontal tissues were removed and prepared for histological examination. RESULTS: Besides cementum-like, bone-like, and periodontal ligament-like tissues formed in the canals, residual remaining pulp tissue was observed in two revascularized teeth. In four teeth, ingrowth of alveolar bone into the canals was seen; presence of bone in the root canals has the potential for ankylosis. CONCLUSIONS: Within the limitation of this study, it can be concluded that residual pulp tissue can remain in the canals after revascularization procedures of immature teeth with artificially induced pulp infection. This can lead to the misinterpretation that true pulpal regeneration has occurred. Ingrowth of apical bone into the root canals undergoing revascularization can interfere with normal tooth eruption if ankylosis occurs.

Clinical and radiographic outcomes of traumatized immature permanent necrotic teeth after revascularization/revitalization therapy.

INTRODUCTION: Revascularization treatment is rapidly becoming an accepted treatment alternative for the management of endodontic pathology in immature permanent teeth with necrotic dental pulps. However, the success and timing of clinical resolution of symptoms, and radiographic outcomes of interest, such as continued hard tissue deposition within the root, are largely unknown. METHODS: In this prospective cohort study, 20 teeth were treated with a standardized revascularization treatment protocol and monitored for clinical and radiographic changes for 1 year. Standardized radiographs were collected at regular intervals, and radiographic changes were quantified. RESULTS: All 20 treated teeth survived during the 12-month follow-up period, and all 20 also met the clinical criteria for success at 12 months. As a group, the treated teeth showed a statistically significant increase in radiographic root width and length and a decrease in apical diameter, although the changes in many cases were quite small (such that the clinical significance is unclear). The within-case percent change in apical diameter after 3 months was 16% and had increased to 79% by 12 months, with 55% (11/20) showing complete apical closure. The within-case percent change in root length averaged less than 1% at 3 months and increased to 5% at 12 months. The within-case percent change in root thickness averaged 3% at 3 months and 21% at 12 months. CONCLUSIONS: Although clinical success was highly predictable with this procedure, clinically meaningful radiographic root thickening and lengthening are less predictable after 1-year of follow-up. Apical closure is the most consistent radiographic finding.