Antimicrobial activity of different filling pastes for deciduous tooth treatment

Efficacy of antibiotic and iodoform pastes in non-instrumental endodontic treatment of anterior primary teeth-Protocol for a randomized controlled clinical

The maintenance of the deciduous tooth until its physiological exfoliation occurs is one of the main objectives of pediatric dentistry. Endodontic treatment in deciduous teeth resulting from carious or traumatic lesions with pulpal involvement is often necessary and we often find it difficult to perform it, due to the difficult control of the child, the internal anatomy of the root canals, and root resorptions. The non-instrumental endodontic treatment technique (NIET) associated with antimicrobial drugs has advantages such as shorter chair time and less complexity than the conventional technique in which root canal instrumentation is performed. The aim of this study is to carry out a controlled and randomized clinical trial to compare the effectiveness of (NIET) in primary teeth associated with the use of two obturator pastes. One hundred and twenty necrotic deciduous teeth of children aged between 3 and 6 years will be selected; and the teeth will be divided into two groups. In Group 1 and Group 2, root canals will not be instrumented, just irrigated and filled with the respective pastes, antibiotic (CTZ) and iodoform (Guedes-Pinto). Presence of fistula and mobility will be clinically evaluated. The evaluations will be carried out in both groups on the day of treatment and in periods of 1, 3 and 6 months after treatment. For the main outcome, the tooth will be the unit of analysis and the Kaplan-Meier test will be performed to estimate the survival rates of the included teeth. For comparison between the two groups, Student's t test or Mann-Whitney test will be performed, depending on the normality of the data. In addition, Poisson regression analyzes will be carried out, in order to allow the evaluation of the influence of some variables on the results. For all analyses, the significance value will be adjusted to 5%. Trial registration: NCT04587089 in ClinicalTrials.gov. Approval date: May 15, 2023.

Chitosan nanoparticles efficiently enhance the dispersibility, stability and selective antibacterial activity of insoluble isoflavonoids

Natural isoflavonoids have attracted much attention in the treatment of oral bacterial infections and other diseases due to their excellent antibacterial activity and safety. However, their poor water solubility, instability and low bioavailability seriously limited the practical application. In this study, licoricidin-loaded chitosan nanoparticles (LC-CSNPs) were synthesized by self-assembly for improving the dispersion of licoricidin (LC) and strengthening antibacterial and anti-biofilm performance. Compared to free LC, the minimum inhibitory concentration of LC-CSNPs against Streptococcus mutans decreased >2-fold to 26 μg/mL, and LC-CSNPs could ablate 70 % biofilms at this concentration. The enhanced antibacterial activity was mainly attributed to the spontaneous surface adsorption of LC-CSNPs on cell membranes through electrostatic interactions. More valuably, LC-CSNPs had no inhibitory effect on the growth of probiotic. Mechanism study indicated that LC-CSNPs altered the transmembrane potential to cause bacterial cells in a hyperpolarized state, generating ROS to cause cells damage and eventually apoptosis. This work demonstrated that the chitosan-based nanoparticles have great potential in enhancing the dispersibility and antibacterial activity of insoluble isoflavonoids, offering a promising therapeutic strategy for oral infections.

Root canal filling materials for endodontic treatment of necrotic primary teeth: a network meta-analysis

PURPOSE

To investigate the effect of different root canal filling materials on the change of failure of the endodontic treatment of necrotic primary teeth.

METHODS

A literature search was carried out in PubMed/MEDLINE, CENTRAL, Scopus databases, and grey literature up to July 2022 selecting randomised clinical trials related to research question. Two reviewers independently selected the studies, extracted the data, and assessed the bias risk. Root canal filling materials were grouped according to the main component [iodoform (IOD), calcium hydroxide (CAOH), zinc oxide (ZO) or mix (IOD plus CAOH plus ZO) pastes]. Pairwise and network meta-analyses using the mixed treatment comparisons method were performed to compare the number of events (failure) among treatments. Odds ratio and 95% confidence intervals (CI) for calculated. Post-probabilities among treatments were also calculated and interpreted.

RESULTS

From 1186 potentially relevant studies, 17 were selected for full-text analysis, and 7 were included in the meta-analysis, totalizing 263 teeth. In the direct evidence, ZO pastes resulted in a higher chance of failure than IOD pastes (OR 7.07 95% CI 1.02, 62.59). In the indirect evidence, there was no difference between the materials. The IOD pastes presented a high probability (81%) of being the treatment associated to lowest number of failures among all treatments. The CAOH pastes presented the highest probability of being the worst option. Studies showed high bias risk.

CONCLUSION

There is currently no scientific evidence of the superiority of any one root canal filling material for endodontic treatment of necrotic primary teeth.

Physicochemical properties and filling capacity of an experimental iodoform-based paste in primary teeth

In this study, we evaluated the physicochemical properties (PCP; radiopacity, flow, pH, and solubility) and the quality of root canal filling provided by an experimental industrialized paste (EP), with the same active ingredients as those of the Guedes Pinto paste, compared with the Vitapex® paste. PCP were analyzed according to the ANSI/ADA laboratory testing methods for endodontic filling and sealing materials. To analyze filling capacity, 120 artificial primary teeth (60 maxillary incisors [MIs] and 60 mandibulary molars [MMs]) were endodontically treated. The teeth were divided into eight groups based on the dental group (MIs or MMs), filling material (Vitapex® or EP), and insertion method (syringe or lentulo). The Image J® software was used to analyze the initial an final digital radiographies of each tooth, measuring and comparing root canal and void areas. The percentage of filling failure areas was obtained. Data were submitted to ANOVA and Tukey test of mean comparison. Regarding PCP, both pastes presented results according the ANSI/ADA standards. Flow capacity: Vitapex: 19.6 mm, EP: 25 mm (p < 0.01); radiopacity: Vitapex: 4.47 mmAl, EP: 6.06 mmAl (p < 0.01); pH after 28 days: Vitapex: 7.79, EP: 8.19 (p = 0.12); and solubility after 28 days: Vitapex: 2.68%, EP: 2.89% (p > 0.05). Regarding filling capacity analysis, EP demonstrated 12.5% of failure against 31.5% of Vitapex (p < 0.01). Compared to Vitapex, EP presented statistically significantly better results in flow, radiopacity, pH, and filling capacity. Molars presented more filling failures than incisors. The insertion method using a syringe and a thin tip was significantly better than that using Lentulo spiral carriers.

Cytocompatibility of filling pastes by primary teeth root simulating model

Evaluate the cytocompatibility of Calen^®/ZO, Calcicur^®, Vitapex^®, Endoflas^®, and zinc oxide/eugenol-based (ZOE) root canal pastes (RCP) to human primary osteoblasts (HPO) through a simplified model for primary teeth. The model employed pipette tips filled with 0.037 g of paste, exposed to 185 µL of culture medium for 24 h (n = 6). Release of components was analysed by Proton Nuclear Magnetic Resonance Spectroscopy (¹H-NMR). HPO were exposed to conditioned media for 24 h. Cell viability was assessed by cell density and metabolic activity, and release of interleukin 6 (IL-6), vascular endothelial growth factor (VEGF) and fibroblast growth factor (bFGF) by immunological assay. Physicochemical properties and antimicrobial efficacy were also evaluated. ¹H-NMR spectra analysis showed similarity between ZOE, Endoflas^®, Calcicur^®, and Vitapex^® compared to Calen^®/ZO and positive control, which showed distinct released components. Calen^®/ZO and Calcicur^® exhibited high alkaline pH in all periods and showed similar solubility. Calen^®/ZO, ZOE, and Vitapex^® showed similar flow rate. Calen^®/ZO, Calcicur^®, and Vitapex^® did not exhibit antimicrobial efficacy. Calen^®/ZO presented cytotoxicity (p < 0.05). Pastes did not increase IL-6 release compared to control. Apart from Vitapex^®, all pastes significantly induced VEGF/bFGF release. Interactive effects among released products may affect biological response to filling pastes. Calcicur^®, ZOE, Endoflas^® and Calen^®/ZO presented good to moderate cytocompatibility, with low impact on pro-inflammatory cytokine release and induction of growth factors of interest to tissue repair. This simplified model, specific for the evaluation of the cytocompatibility of RCPs on primary teeth, suggests how these pastes might contribute to bone repair in clinical situations of apical periodontitis in children.