Comparison of the physical properties of glass ionomer modified with silver phosphate/hydroxyapatite or titanium dioxide nanoparticles: in vitro study.

Glass ionomer cements (GICs) are the common materials employed in pediatric dentistry because of their specific applications in class I restorations and atraumatic restoration treatments (ART) of deciduous teeth in populations at high risk of caries. Studies show a limited clinical durability of these materials. Attempts have thus been made to incorporate nanoparticles (NPs) into the glass ionomer for improving resistance and make it like the tooth structure. An in vitro experimental study was conducted using the required samples dimensions and prepared based on the test being carried out on the three groups with or without the modification of light-cured glass ionomer. Samples were grouped as follows: control group (G1_C), 2% silver phosphate/hydroxyapatite NPs group (G2_SPH), and 2% titanium dioxide NPs group (G3_TiO2). The physical tests regarding flexural strength (n = 10 per group), solubility (n = 10 per group), and radiopacity (n = 3 per group) were performed. The data were analyzed by Shapiro Wilks test, and one-way analysis of variance (one-way ANOVA), and multiple comparisons by post hoc Tukey's test. The p-value of < 0.05 was considered significant. No statistically significant difference was observed between the control group (G1_C) and (G2_SPH) (p = 0.704) in the flexural strength test, however differences were found between G2_SPH and G3_TiO2 groups, ANOVA (p = 0.006); post hoc Tukey's test (p = 0.014). Pertaining to the solubility, G2_SPH obtained the lowest among the three groups, ANOVA (p = 0.010); post hoc Tukey's test (p = 0.009). The three study groups obtained an adequate radiopacity of >1 mm Al, respectively. The resin-modified glass ionomer cement (RMGIC) was further modified with 2% silver phosphate/hydroxyapatite NPs to improve the physical properties such as enhancing the solubility and sorption without compromising the flexural strength and radiopacity behavior of modified RMGIC. The incorporation of 2% titanium dioxide NPs did not improve the properties studied.

Wrinkled TiNAgNW Nanocomposites for High-Performance Flexible Electrodes on TEMPO-Oxidized Nanocellulose.

In this study, we present a novel method for fabricating semi-transparent electrodes by combining silver nanowires (AgNW) with titanium nitride (TiN) layers, resulting in conductive nanocomposite coatings with exceptional electromechanical properties. These nanocomposites were deposited on cellulose nanopaper (CNP) using a plasma-enhanced pulsed laser deposition (PE-PLD) technique at low temperatures (below 200 °C). Repetitive bending tests demonstrate that incorporating AgNW into TiN coatings significantly enhances the microstructure, increasing the electrode's electromechanical robustness by up to four orders of magnitude compared to commercial PET/ITO substrates. Furthermore, the optical and electrical conductivities can be optimized by adjusting the AgNW network density and TiN synthesis temperature. Our results also indicate that the nanocomposite electrodes exhibit improved stability in air and superior adhesion compared to bare AgNW coatings.

Custom-made Trabecular Metal Acetabular Component in Total Hip Revision.

The following case report aims to demonstrate a total hip arthroplasty revision surgery (THARS) using a custom-made trabecular metal acetabular component for correction of a severe acetabular defect. Currently, in the literature, there are few complete descriptions of surgical planning and procedures involving customized prostheses. This is due to the inherent technical difficulty of the surgical procedure and the high costs related to the planning and materials.

Antiprotozoal, Anthelmintic and Antivectorial Activities of Titanium Dioxide Nanoparticles.

Nanotechnology has been established as a promising alternative for treating a myriad of disease-causing microorganisms that pose threats to human health. The utilization of nanoparticles (NPs) emerges as a strategy to enhance the therapeutic arsenal against these diseases, especially given the tendency of many pathogens to develop resistance to conventional medications. Notably, titanium dioxide nanoparticles (TiO2NPs) have garnered attention for their multifaceted biomedical applications, encompassing antibacterial, antifungal, antiviral, anticancer, antioxidant, and drug delivery properties. This review focuses on the cutting-edge potential of TiO2NPs against helminths, protozoa, and vectors, underscoring their pivotal role in combating these health-threatening agents.

Titanium: A systematic review of the relationship between crystallographic profile and cell adhesion.

Dental implant surface properties such as roughness, wettability, and porosity ensure cell interaction and tissue integration. The clinical performance of dental implants depends on the crystallographic texture and protein and cell bonds to the substrates, where grain size, orientation, and inclination are parameters responsible for favoring osteoblast adhesion and limiting bacterial adhesion. The lack of consensus on the best crystallographic plan for cell adhesion prompted this systematic review, which aims to answer the following question: "What is the influence of the crystallographic plane on titanium surfaces on cell adhesion?" by evaluating the literature on the crystallographic characteristics of titanium and how these dictate topographical parameters and influence the cell adhesion of devices made from this material. It followed the Preferred Reporting Standards for Systematic Reviews and Meta-Analyses (PRISMA 2020) registered with the Open Science Framework (OSF) (osf.io/xq6kv). The search strategy was based on the PICOS method. It chose in vitro articles that analyzed crystallographic structure correlated with cell adhesion and investigated the microstructure and its effects on cell culture, different crystal orientation distributions, and the influence of crystallinity. The search strategies were applied to the different electronic databases: PubMed, Scopus, Science Direct, Embase, and Google Scholar, and the articles found were attached to the Rayyan digital platform and assessed blindly. The Joanna Bringgs Institute (JBI) tool assessed the risk of bias. A total of 248 articles were found. After removing duplicates, 192 were analyzed by title and abstract. Of these, 18 were selected for detailed reading in their entirety, 9 of which met the eligibility criteria. The included studies presented a low risk of bias. The role of the crystallographic orientation of the exposed faces in a multicrystalline material is little discussed in the scientific literature and its impact is recognized as dictating the topographical characteristics of the material that facilitate cell adhesion.

Successful application of photocatalytic recycled TiO2-GO membranes for the removal of trace organic compounds from tertiary effluent.

Photocatalytic membranes are a promising technology for water and wastewater treatment. Towards circular economy, extending the lifetime of reverse osmosis (RO) membranes for as long as possible is extremely important, due to the great amount of RO modules discarded every year around the world. Therefore, in the present study, photocatalytic membranes made of recycled post-lifespan RO membrane (polyamide thin-film composite), TiO2 nanoparticles and graphene oxide are used in the treatment tertiary-treated domestic wastewater to remove trace organic compounds (TrOCs). The inclusion of dopamine throughout the surface modification process enhanced the stability of the membranes to be used as long as 10 months of operation. We investigated TrOCs removal by the membrane itself and in combination with UV-C and visible light by LED. The best results were obtained with integrated membrane UV-C system at pH 9, with considerable reductions of diclofenac (92%) and antipyrine (87%). Changes in effluent pH demonstrated an improvement in the attenuation of TrOCs concentration at higher pHs. By modifying membranes with nanocomposites, an increase in membrane hydrophilicity (4° contact angle reduction) was demonstrated. The effect of the lamp position on the light fluence that reaches the membrane was assessed, and greater values were found in the middle of the membrane, providing parameters for process optimization (0.29 ± 0.10 mW cm-2 at the center of the membrane and 0.07 ± 0.03 mW cm-2 at the right and left extremities). Photocatalytic recycled TiO2-GO membranes have shown great performance to remove TrOCs and extend membrane lifespan, as sustainable technology to treat wastewater.

Investigating the Metal-TiO2 Influence for Highly Selective Photocatalytic Oxidation of Methane to Methanol.

Methane conversion to valuable chemicals is a highly challenging and desirable reaction. Photocatalysis is a clean pathway to drive this chemical reaction, avoiding the high temperature and pressure of the syngas process. Titanium dioxide, being the most used photocatalyst, presents challenges in controlling the oxidation process, which is believed to depend on the metal sites on its surface that function as heterojunctions. Herein, we supported different metals on TiO2 and evaluated their activity in methane photooxidation reactions. We showed that Ni-TiO2 is the best photocatalyst for selective methane conversion, producing impressively high amounts of methanol (1.600 µmol·g-1) using H2O2 as an oxidant, with minimal CO2 evolution. This performance is attributed to the high efficiency of nickel species to produce hydroxyl radicals and enhance H2O2 utilization as well as to induce carrier traps (Ti3+ and SETOVs sites) on TiO2, which are crucial for C-H activation. This study sheds light on the role of catalyst structure in the proper control of CH4 photoconversion.

Chronic exposure to TiO2 micro- and nano particles: A biochemical and histopathological experimental study.

The aim of this work was to analyze the effects of long-term exposure to titanium dioxide (TiO2) micro- (MPs) and nanoparticles (NPs) (six and 12 months) on the biochemical and histopathological response of target organs using a murine model. Male Wistar rats were intraperitoneally injected with a suspension of TiO2 NPs (5 nm; TiO2-NP5 group) or MPs (45 µm; TiO2-NP5 group); the control group was injected with saline solution. Six and 12 months post-injection, titanium (Ti) concentration in plasma and target organs was determined spectrometrically (ICP-MS). Blood smears and organ tissue samples were evaluated by light microscopy. Liver and kidney function was evaluated using serum biochemical parameters. Oxidative metabolism was assessed 6 months post-injection (determination of superoxide anion by nitroblue tetrazolium (NBT) test, superoxide dismutase (SOD) and catalase (CAT), lipid peroxidation, and paraoxonase 1). Titanium (Ti) concentration in target organs and plasma was significantly higher in the TiO2-exposed groups than in the control group. Histological evaluation showed the presence of titanium-based particles in the target organs, which displayed no structural alterations, and in blood monocytes. Oxidative metabolism analysis showed that TiO2 NPs were more reactive over time than MPs (p < .05) and mobilization of antioxidant enzymes and membrane damage varied among the studied organs. Clearance of TiO2 micro and nanoparticles differed among the target organs, and lung clearance was more rapid than clearance from the lungs and kidneys (p < .05). Conversely, Ti concentration in plasma increased with time (p < .05). In conclusion, neither serum biochemical parameters nor oxidative metabolism markers appear to be useful as biomarkers of tissue damage in response to TiO2 micro- and nanoparticle deposits at chronic time points.

Impact of the spatial orientation of the patient's head, metal artifact reduction, and tube current on cone-beam computed tomography artifact expression adjacent to a dental implant: A laboratory study using a simulated surgical guide.

Purpose: The aim of this study was to evaluate image artifacts in the vicinity of dental implants in cone-beam computed tomography (CBCT) scans obtained with different spatial orientations, tube current levels, and metal artifact reduction algorithm (MAR) conditions. Materials and Methods: One dental implant and 2 tubes filled with a radiopaque solution were placed in the posterior region of a mandible using a surgical guide to ensure parallel alignment. CBCT scans were acquired with the mandible in 2 spatial orientations in relation to the X-ray projection plane (standard and modified) at 3 tube current levels: 5, 8, and 11 mA. CBCT scans were repeated without the implant and were reconstructed with and without MAR. The mean voxel and noise values of each tube were obtained and compared using multi-way analysis of variance and the Tukey test (α=0.05). Results: Mean voxel values were significantly higher and noise values were significantly lower in the modified orientation than in the standard orientation (P<0.05). MAR activation and tube current levels did not show significant differences in most cases of the modified spatial orientation and in the absence of the dental implant (P>0.05). Conclusion: Modifying the spatial orientation of the head increased brightness and reduced spatial orientation noise in adjacent regions of a dental implant, with no influence from the tube current level and MAR.

Influence of the Surface Topography of Titanium Dental Implants on the Behavior of Human Amniotic Stem Cells.

The dental implant surface plays a crucial role in osseointegration. The topography and physicochemical properties will affect the cellular functions. In this research, four distinct titanium surfaces have been studied: machined acting (MACH), acid etched (AE), grit blasting (GBLAST), and a combination of grit blasting and subsequent acid etching (GBLAST + AE). Human amniotic mesenchymal (hAMSCs) and epithelial stem cells (hAECs) isolated from the amniotic membrane have attractive stem-cell properties. They were cultured on titanium surfaces to analyze their impact on biological behavior. The surface roughness, microhardness, wettability, and surface energy were analyzed using interferometric microscopy, Vickers indentation, and drop-sessile techniques. The GBLAST and GBLAST + AE surfaces showed higher roughness, reduced hydrophilicity, and lower surface energy with significant differences. Increased microhardness values for GBLAST and GBLAST + AE implants were attributed to surface compression. Cell viability was higher for hAMSCs, particularly on GBLAST and GBLAST + AE surfaces. Alkaline phosphatase activity enhanced in hAMSCs cultured on GBLAST and GBLAST + AE surfaces, while hAECs showed no mineralization signals. Osteogenic gene expression was upregulated in hAMSCs on GBLAST surfaces. Moreover, α2 and ß1 integrin expression enhanced in hAMSCs, suggesting a surface-integrin interaction. Consequently, hAMSCs would tend toward osteoblastic differentiation on grit-blasted surfaces conducive to osseointegration, a phenomenon not observed in hAECs.

Formation of Olive-like TiO2 Nanospheres in a Polymeric Mesh by Sol-Gel Method.

Olive-like TiO2 (titanium dioxide), nanospheres compounds were synthesized. Polysaccharide (1-3 linked ß-D galactapyranose and 1.4-linked 3.6 anyhdro-α-L-galactopyranose and titanium isopropoxide (IV) was used as a precursor in its formation. The powder sample was evaluated by scanning tunneling microscope, X-ray diffraction pattern, power spectral density, fast Fourier transform, differential thermal analysis, continuous wavelet transform, and isotropy texture analysis. The results demonstrate that these nanospheres can successfully be synthesized in a solution using a polysaccharide network by means of the sol-gel method. The synthesized olive-like TiO2 nanospheres have diameters ranging from 50 nm to 500 nm. The synthesis parameters, such as temperature, time, and concentration of the polysaccharide, were controlled in solution.

Production and characterization of the lipopeptide with anti-adhesion for oral biofilm on the surface of titanium for dental implants.

Titanium implants are subject to bacterial adhesion and peri-implantitis induction, and biosurfactants bring a new alternative to the fight against infections. This work aimed to produce and characterize the biosurfactant from Bacillus subtilis ATCC 19,659, its anti-adhesion and antimicrobial activity, and cell viability. Anti-adhesion studies were carried out against Streptococcus sanguinis, Staphylococcus aureus, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Proteus mirabilis as the minimum inhibitory concentration and the minimum bactericidal concentration. Cell viability was measured against osteoblast and fibroblast cells. The biosurfactant was classified as lipopeptide, with critical micelle concentration at 40 µg mL- 1, and made the titanium surface less hydrophobic. The anti-adhesion effect was observed for Staphylococcus aureus and Streptococcus sanguinis with 54% growth inhibition and presented a minimum inhibitory concentration of 15.7 µg mL- 1 for Streptococcus sanguinis and Aggregatibacter actinomycetemcomitans. The lipopeptide had no cytotoxic effect and demonstrated high potential application against bacterial biofilms.

Probabilistic material flow analysis of released nano titanium dioxide in Mexico.

Engineered Nanomaterials (ENMs) or products containing ENMs, known as nano-enabled products are commercialized globally by a large number of companies. Concern about the potential risks and negative impacts of releasing ENMs into the environment is under investigation. For this reason, methodologies to estimate the probable mass concentrations of ENMs released in different regions of the world have been developed. As a first attempt to estimate the probable mass flows of nanosized titanium dioxide (nano-TiO2) released in Mexico, we developed a Probabilistic Material Flow Analysis (PMFA) for 2015. The model describes probabilistic mass flows of released nano-TiO2 during the life cycle of sunscreens, coatings, ceramic, and other nano-enabled products, including the flows through the solid waste and wastewater management systems, as well as the transfer of nano-TiO2 to three environmental compartments (atmosphere, topsoil, and surface water). The PMFA incorporates the uncertainty related to the input data. We observed that the most significant nano-TiO2 flows occur to the surface water, landfill, and soil compartments, targeted as the main "hot-spots", where living organisms could be more exposed to this material. Further improvements in the model are needed due to some data gaps at some life cycle stages, for instance, solid waste management and reused wastewater manipulation for irrigation purposes. Finally, the model developed in this study can be adjusted to assess other ENM releases and can be beneficial for further investigation in fate modeling and environmental risk assessment.

Fifteen years of engine-driven nickel-titanium reciprocating instruments, what do we know so far? An umbrella review.

Numerous systematic reviews (SRs) have produced conflicting findings on engine-driven nickel-titanium reciprocating instruments (reciprocating instruments) since Yared's seminal study 15 years ago. This umbrella review analysed SRs examining the clinical and laboratory evidence regarding reciprocating instruments for root canal treatment. SRs that evaluated qualitatively and/or quantitatively the outcomes postoperative pain, oral health-related quality of life (OHRQoL), shaping ability, debris extrusion, microbial load, endotoxins reduction, cyclic fatigue, file fracture, dentinal cracks and root canal filling removal were included. The AMSTAR 2 tool was used to evaluate SRs quality, while the ROBIS tool to assess risk of bias (RoB). Forty SRs were included. The SRs revealed predominantly 'high' RoB and 'critically low' quality. Most focused on technical outcomes, exhibiting significant methodological and statistical heterogeneity. Findings suggest comparable efficacy between reciprocating and rotary instruments. However, due to the scarcity of high-quality evidence, future well-designed studies and reviews considering core outcome measures are needed.

Amorphous titanium oxide (aTiO2) thin films biofunctionalized with CAP-p15 induce mineralized-like differentiation of human oral mucosal stem cells (hOMSCs).

Insufficient osseointegration of titanium-based implants is a factor conditioning their long-term success. Therefore, different surface modifications, such as multifunctional oxide coatings, calcium phosphates, and the addition of molecules such as peptides, have been developed to improve the bioactivity of titanium-based biomaterials. In this work, we investigate the behavior of human oral mucosal stem cells (hOMSCs) cultured on amorphous titanium oxide (aTiO2), surfaces designed to simulate titanium (Ti) surfaces, biofunctionalized with a novel sequence derived from cementum attachment protein (CAP-p15), exploring its impact on guiding hOMSCs towards an osteogenic phenotype. We carried out cell attachment and viability assays. Next, hOMSCs differentiation was assessed by red alizarin stain, ALP activity, and western blot analysis by evaluating the expression of RUNX2, BSP, BMP2, and OCN at the protein level. Our results showed that functionalized surfaces with CAP-p15 (1 µg ml-1) displayed a synergistic effect increasing cell proliferation and cell attachment, ALP activity, and expression of osteogenic-related markers. These data demonstrate that CAP-p15 and its interaction with aTiO2surfaces promote osteoblastic differentiation and enhanced mineralization of hOMSCs when compared to pristine samples. Therefore, CAP-p15 shows the potential to be used as a therapeutical molecule capable of inducing mineralized tissue regeneration onto titanium-based implants.

Exfoliation of titanium nitride using a non-thermal plasma process.

In this study, we present a novel approach for the exfoliation of titanium nitride (TiN) powders utilizing a rapid, facile, and environmentally friendly non-thermal plasma method. This method involves the use of an electric arc and nitrogen as the ambient gas at room temperature to generate ionized particles. These ionized species interact with the ceramic crystal of TiN, resulting in a pronounced structural expansion. The exfoliated TiN products were comprehensively characterized using transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Remarkably, the cubic crystal structure of TiN was effectively retained, while the (200) crystal plane d-spacing increased from 2.08 to 3.09 Å, accompanied by a reduction in crystallite size and alterations in Raman vibrational modes. Collectively, these findings provide compelling evidence for the successful exfoliation of TiN structures using our innovative non-thermal plasma method, opening up exciting possibilities for advanced material applications.

Oral Exposure to Titanium Dioxide E171 and Zinc Oxide Nanoparticles Induces Multi-Organ Damage in Rats: Role of Ceramide.

Food-grade titanium dioxide (E171) and zinc oxide nanoparticles (ZnO NPs) are common food additives for human consumption. We examined multi-organ toxicity of both compounds on Wistar rats orally exposed for 90 days. Rats were divided into three groups: (1) control (saline solution), (2) E171-exposed, and (3) ZnO NPs-exposed. Histological examination was performed with hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM). Ceramide (Cer), 3-nitrotyrosine (NT), and lysosome-associated membrane protein 2 (LAMP-2) were detected by immunofluorescence. Relevant histological changes were observed: disorganization, inflammatory cell infiltration, and mitochondrial damage. Increased levels of Cer, NT, and LAMP-2 were observed in the liver, kidney, and brain of E171- and ZnO NPs-exposed rats, and in rat hearts exposed to ZnO NPs. E171 up-regulated Cer and NT levels in the aorta and heart, while ZnO NPs up-regulated them in the aorta. Both NPs increased LAMP-2 expression in the intestine. In conclusion, chronic oral exposure to metallic NPs causes multi-organ injury, reflecting how these food additives pose a threat to human health. Our results suggest how complex interplay between ROS, Cer, LAMP-2, and NT may modulate organ function during NP damage.

Ecotoxicological assessment of UV filters benzophenone-3 and TiO2 nanoparticles, isolated and in a mixture, in developing zebrafish (Danio rerio).

The increasing use of UV filters, such as benzophenone-3 (BP-3) and titanium dioxide nanoparticles (TiO2 NPs), has raised concerns regarding their ecotoxicological effects on the aquatic environment. The aim of the present study was to examine the embryo-larval toxicity attributed to BP-3 or TiO2 NPs, either alone or in a mixture, utilizing zebrafish (Danio rerio) as a model after exposure to environmentally relevant concentrations of these compounds. Zebrafish embryos were exposed to BP-3 (10, 100, or 1000 ng/L) or TiO2 NPs (1000 ng/L) alone or in a mixture (BP-3 10, 100, or 1000 ng/L plus 1000 ng/L of TiO2 NPs) under static conditions for 144 hr. After exposure, BP-3 levels were determined by high-performance liquid chromatography (HPLC). BP-3 levels increased in the presence of TiO2 NPs, indicating that the BP-3 degradation decreased in the presence of the NPs. In addition, in the presence of zebrafish, BP-3 levels in water decreased, indicating that zebrafish embryos and larvae might absorb BP-3. Data demonstrated that, in general, environmentally relevant concentrations of BP-3 and TiO2 NPs, either alone or in a mixture, did not significantly induce changes in heart and spontaneous contractions frequencies, levels of reactive oxygen species (ROS), morphological and morphometric parameters as well as mortality rates during 144 hr exposure. However, the groups exposed to TiO2 NPs alone and in a mixture with BP-3 at 10 ng/L exhibited an earlier significant hatching rate than the controls. Altogether, the data indicates that a potential ecotoxicological impact on the aquatic environment exists.

Effect of Surface Treatment on Titanium Surface Free Energy and its Relation to Bacterial Activity: A Systematic Review.

The surface properties of titanium dental implants, such as wettability and surface free energy, influence the adhesion of microorganisms responsible for inflammation and infection of peri-implant tissues. This systematic review aimed to investigate the relationship of titanium surface treatments, surface free energy/wettability property and its relationship with bacterial activity. This systematic review followed PRISMA 2020 (Preferred Reporting Items for Systematic Review and MetaAnalysis) guidelines and was registered in the OpenScience Framework (osf.io/ejnct). PubMed, ScienceDirect, Embase, and Scopus library databases were used from custom search strategies. Inclusion criteria were research articles that studied titanium or its alloys for wetting property and its correlation with adhesion. Of the 697 articles initially identified, 27 were selected after full-text reading and application of the eligibility criteria. In general, the evaluated studies showed that regardless of the surface treatment, there was an increase in titanium hydrophilicity and concomitant reduction in bacterial adhesion. The surface treatment of titanium results in higher surface free energy and lower bacterial adhesion. Hydrophilic titanium surfaces prevent adhesion of hydrophobic bacteria in early stages.

Dynamic Photoelastic Analysis of Stress Distribution in Simulated Canals Using Rotary Instruments with Varied Tip and Taper Sizes: A Quasi-3D Approach.

INTRODUCTION: To compare the stress produced on the walls of simulated canals by rotary instruments with varied tip and taper sizes. METHODS: Ninety isotropic transparent blocks, each containing a 60-degree curved canal, were distributed into 18 groups (n = 5) based on the instrument tip (sizes 10, 15, 20, 25, 30, and 35) and taper (sizes 0.02, 0.04, and 0.06). The blocks were fixed in a circular polariscope setup for dark field analysis. A digital camera was employed to capture the real-time birefringence patterns generated by each instrument. Digital image frames, corresponding to the instrument reaching the end of each canal third, were extracted and evaluated by 2 independent observers for the stress generation on canal walls. The data analysis employed a semi-quantitative scale ranging from 0 to 5. Cohen's Kappa coefficient test was used to determine the inter-observer agreement while the results were compared using Kruskal-Wallis test followed by an all-pairwise posthoc procedure (α = 5%). RESULTS: Inter-observer agreement was 0.95. A significant influence of the tip size on stress was observed across the coronal (P = .011), middle (P = .006), and apical (P = .026) thirds. In contrast, taper size did not affect the stress induced at the coronal (P = .509), middle (P = .958), or apical (P = .493) thirds. The variations in tip and taper sizes did not result in a significant stress differences among the thirds (P = .181). CONCLUSIONS: The stress significantly increased across all canal thirds with larger tip sizes of rotary instruments, whereas the taper sizes did not influence the stress when compared to the canal thirds.