Sodium hypochlorite (NaOCl), as the most commonly used irrigant solution, offers strong antibacterial and organic tissue dissolving properties and has the potential to express a strong corrosive effect. The aim of the study was to evaluate the effects of NaOCl on corrosion behavior and cyclic fatigue in five different types of NiTi rotary endodontic instruments. The study examined: ProTaper Universal, ProTaper Next, Twisted File, HyFlex CM, and BioRace, each with 24 samples. Each group was divided into a control subgroup and a subgroup exposed to electrochemical testing of corrosion in 5.25% NaOCl. All instruments were exposed to a cyclic fatigue test in artificial canals with a curvature angle of 60 degrees and radius of 2 mm. The corrosion potential of NaOCl was determined in all groups of instruments. ProTaper Universal had a significantly lower corrosion resistance than ProTaper Next (p < 0.05), Twisted File, BioRace, and HyFlex CM (p < 0.001). HyFlex CM showed significantly higher resistance to cyclic fatigue compared to all the other groups of instruments (p < 0.001). Surface corrosion reduced cyclic fatigue resistance in most of the instrument groups, except in heat-treated instruments with controlled memory. HyFlex CM has proven to have the highest resistance to corrosion and cyclic fatigue.

Background: Numerous plant-derived products have shown notable potential in preclinical studies and traditional use for the management of periodontitis, although clinical studies validating their efficacy remain scarce. The present study investigated the efficacy of a polyherbal phytopreparation as an adjunctive therapy to scaling and root planing (SRP) in patients with periodontitis, and further examined its underlying mechanisms of action, pharmacokinetic behavior, and toxicological profile using in silico approaches. Methods: Eighty patients with moderate periodontitis (stage II, grade A) were randomly assigned to two groups: a control group (n = 40) treated with SRP alone, and an experimental group (n = 40) receiving SRP followed by topical phytotherapeutic treatment with the polyherbal Tinctura paradentoica^®. Efficacy was evaluated using the gingival index, periodontal pocket depth, and cytomorphometric analysis of gingival cells before treatment and one month after. The in silico analysis, guided by HPLC profiling, included MolDock-based docking to assess interactions of bioactive compounds with cyclooxygenase isoforms COX-1 and COX-2 as anti-inflammatory targets, and evaluation of their pharmacokinetic and toxicity properties (ADME/Tox) using SwissADME, ProTox-3.0, and pkCSM. Results: Compared with SRP treatment, the experimental treatment significantly reduced the gingival index and periodontal pocket depth (p < 0.05), as well as the assessed cytomorphometric parameters (nuclear area, perimeter, and Feret’s diameter values) (p < 0.001). Rerank analysis revealed van der Waals-driven isoform selectivity: compact phenolic acids and aglycones favored COX-1, whereas bulky glycosides (e.g., rutin, narcissoside) were optimized for COX-2, with luteolin-7-O-glucoside showing near-balanced engagement. The ADME/Tox analysis indicated generally favorable pharmacokinetic and safety characteristics of phenolic compounds from the phytopreparation, including low systemic absorption and no predicted mutagenicity or skin sensitization potential. Conclusions: The topical application of the polyherbal phytopreparation demonstrated significant potential to enhance the efficacy of conventional SRP therapy by promoting the regression of gingival inflammation in patients with moderate periodontitis, further supported by in silico findings.