Effect of the calcium silicate and sodium phosphate remineralizing products on bleached enamel.

Context and Aims: This study evaluated the effect of calcium silicate and sodium phosphate (CSSP) dentifrice and serum on the surface of enamel bleached with hydrogen peroxide (H2O2). Materials and Methods: A total of 160 bovine enamel slabs were bleached with 35% H2O2 and treated with sodium fluoride (NaF) dentifrice-GI, CSSP dentifrice-GII; CSSP dentifrice + CSSP serum-GIII, or NaF dentifrice + NaF gel-GIV. The dentifrices were applied using a brushing machine three times daily for 7 days. After brushing, sodium phosphate gel and CSSP serum were applied. The microhardness (KNH, n = 14), surface roughness (Ra, n = 14), energy dispersive spectroscopy (n = 6), and scanning electron microscopy (n = 6) were assessed at t0 (before bleaching), t1 (after bleaching), and t2 (after postbleaching treatments). Statistical Analysis Used: The data were subjected to a two-way analysis of variance and Bonferroni's test. Results: The KNH decreased at t1 (P < 0.001) but recovered at t2 for all treatments, although only GII showed restored baseline values (P = 0.0109). The surface roughness increased at t1 (P < 0.001) and reduced at t2 (P < 0.001) for all groups, with no significant differences among groups. Enamel composition and morphology did not differ after the treatments, except for silicon accumulation in GIII. Conclusions: Postbleaching treatment with CSSP dentifrice and serum yielded superior remineralizing effects on bleached enamel.

Efficiency of the photodynamic therapy on viability of Streptococcus mutans in the oral cavity using chitosan nanoparticles: an in vitro study.

PURPOSE: This study aimed to investigate the efficiency of antimicrobial photodynamic therapy (aPDT) on Streptococcus mutans biofilm in the oral cavity using the photosensitizer chloroaluminum phthalocyanine encapsulated in chitosan nanoparticles (ClAlPc/Ch) at three preirradiation times. METHODS: Biofilms of Streptococcus mutans strains (ATCC 25,175) were cultivated on bovine tooth blocks and exposed to a 10% sucrose solution three times a day for 1 min over three consecutive days. The samples were randomly distributed into five treatment groups (n = 5): (I) aPDT with ClAlPc/Ch with a preirradiation time of 5 min (F5), (II) aPDT with ClAlPc/Ch with a preirradiation time of 15 min (F15), (III) aPDT with ClAlPc/Ch with a preirradiation time of 30 min (F30), (IV) 0.12% chlorhexidine digluconate (CHX), and (V) 0.9% saline solution (NaCl). After treatment, the S. mutans biofilms formed on each specimen were collected to determine the number of viable bacteria (colony-forming units (CFU)/mL). Data were analyzed for normality using the Shapiro-Wilk test and the analysis of variance (ANOVA) and Tukey HSD tests to analyze the number of viable bacteria (α = 0.05). RESULTS: The one-way ANOVA showed a difference between the groups (p = 0.0003), and the Tukey HSD posttest showed that CHX had the highest microbial reduction of S. mutans, not statistically different from the F5 and F15 groups, whereas the NaCl group had the lowest microbial reduction statistically similar to the F30 group. CONCLUSION: The results demonstrate that aPDT mediated by ClAlPc/Ch when used at preirradiation times of 5-15 min can be an effective approach in controlling cariogenic biofilm of S. mutans, being an alternative to 0.12% CHX.

Assessing the Risk Stratification of Breast Cancer Polygenic Risk Scores in a Brazilian Cohort.

Polygenic risk scores (PRSs) for breast cancer have a clear clinical utility in risk prediction. PRS transferability across populations and ancestry groups is hampered by population-specific factors, ultimately leading to differences in variant effects, such as linkage disequilibrium and differences in variant frequency (allele frequency differences). Thus, locally sourced population-based phenotypic and genomic data sets are essential to assess the validity of PRSs derived from signals detected across populations. Here, we assess the transferability of a breast cancer PRS composed of 313 risk variants (313-PRS) in a Brazilian trihybrid admixed ancestries (European, African, and Native American) whole-genome sequenced cohort, the Rare Genomes Project. We computed 313-PRS in the Rare Genomes Project (n = 853) using the UK Biobank (UKBB; n = 264,307) as reference. We show that although the Brazilian cohorts have a high European ancestry (EA) component, with allele frequency differences and to a lesser extent linkage disequilibrium patterns similar to those found in EA populations, the 313-PRS distribution is inflated when compared with that of the UKBB, leading to potential overestimation of PRS-based risk if EA is taken as a standard. Interestingly, we find that case controls lead to equivalent predictive power when compared with UKBB-EA samples with area under the receiver operating characteristic curve values of 0.66 to 0.62 compared with 0.63 for UKBB.

Probing the cw-Laser-Induced Fluorescence Enhancement in CsPbBr3 Nanocrystal Thin Films: An Interplay between Photo and Thermal Activation.

Perovskite nanocrystals hold significant promise for a wide range of applications, including solar cells, LEDs, photocatalysts, humidity and temperature sensors, memory devices, and low-cost photodetectors. Such technological potential stems from their exceptional quantum efficiency and charge carrier conduction capability. Nevertheless, the underlying mechanisms of photoexcitation, such as phase segregation, annealing, and ionic diffusion, remain insufficiently understood. In this context, we harnessed hyperspectral fluorescence microspectroscopy to advance our comprehension of fluorescence enhancement triggered by UV continuous-wave (cw) laser irradiation of CsPbBr3 colloidal nanocrystal thin films. Initially, we explored the kinetics of fluorescence enhancement and observed that its efficiency (φph) correlates with the laser power (P), following the relationship φph = 7.7⟨P⟩0.47±0.02. Subsequently, we estimated the local temperature induced by the laser, utilizing the finite-difference method framework, and calculated the activation energy (Ea) required for fluorescence enhancement to occur. Our findings revealed a very low activation energy, Ea ∼ 9 kJ/mol. Moreover, we mapped the fluorescence photoenhancement by spatial scanning and real-time static mode to determine its microscale length. Below a laser power of 60 µW, the photothermal diffusion length exhibited nearly constant values of approximately (22 ± 5) µm, while a significant increase was observed at higher laser power levels. These results were ascribed to the formation of nanocrystal superclusters within the film, which involves the interparticle spacing reduction, creating the so-called quantum dot solid configuration along with laser-induced annealing for higher laser powers.

The Pattern of GH Action in the Mouse Brain.

GH acts in numerous organs expressing the GH receptor (GHR), including the brain. However, the mechanisms behind the brain's permeability to GH and how this hormone accesses different brain regions remain unclear. It is well-known that an acute GH administration induces phosphorylation of the signal transducer and activator of transcription 5 (pSTAT5) in the mouse brain. Thus, the pattern of pSTAT5 immunoreactive cells was analyzed at different time points after IP or intracerebroventricular GH injections. After a systemic GH injection, the first cells expressing pSTAT5 were those near circumventricular organs, such as arcuate nucleus neurons adjacent to the median eminence. Both systemic and central GH injections induced a medial-to-lateral pattern of pSTAT5 immunoreactivity over time because GH-responsive cells were initially observed in periventricular areas and were progressively detected in lateral brain structures. Very few choroid plexus cells exhibited GH-induced pSTAT5. Additionally, Ghr mRNA was poorly expressed in the mouse choroid plexus. In contrast, some tanycytes lining the floor of the third ventricle expressed Ghr mRNA and exhibited GH-induced pSTAT5. The transport of radiolabeled GH into the hypothalamus did not differ between wild-type and dwarf Ghr knockout mice, indicating that GH transport into the mouse brain is GHR independent. Also, single-photon emission computed tomography confirmed that radiolabeled GH rapidly reaches the ventral part of the tuberal hypothalamus. In conclusion, our study provides novel and valuable information about the pattern and mechanisms behind GH transport into the mouse brain.

The impact of race and ethnicity on diffuse large B-cell lymphoma outcomes within the veterans health administration (VHA).

We performed a retrospective chart review of 6266 randomly selected DLBCL patients treated in the VHA nationwide between 1/1/2011 and 12/31/2021. The 3178 patients who met inclusion criteria were predominantly male (97%) and white (75%). Median age of diagnosis for Black patients was 63 years vs 69 years for the entire cohort (p < 0.001). However, patients in each race/ethnicity subgroup presented with similar rates of stage I/II and III/IV disease, IPI score, cell of origin and HIT status. Outcomes analysis revealed similar treatment, response rates, median overall survival, and 1-, 3-, and 5-year survival across all subgroups. Hispanic patients had a 21% lower risk of death (HR = 0.79) than white patients, and Black patients had no significant difference in survival (HR = 0.98). This large retrospective study shows that when standard of care therapy is given within an equal access system, short-term treatment and survival outcomes are the same for all races.

Ironing out obesity.

Obesity is associated with dysfunctions in hypothalamic neurons that regulate metabolism, including agouti-related protein (AgRP)-expressing neurons. In a recent article, Zhang et al. demonstrated that either diet- or genetically induced obesity promoted iron accumulation specifically in AgRP neurons. Preventing iron overload in AgRP neurons mitigated diet-induced obesity and related comorbidities in male mice.

Longevity of composite restorations in posterior teeth placed by dental students: a 12-year retrospective study.

OBJECTIVES: To evaluate the longevity of resin composite restorations placed in posterior teeth by dental students, using data from electronic records from 2008 to 2019. MATERIALS AND METHODS: Demographic (gender and age) and clinical variables (dental group, position in dental arch, and the number of restored surfaces) were evaluated. The 5-year follow-up was assessed according to the day the restoration was placed. Kaplan-Meier curves were generated to calculate the annual failure rate. Data were analyzed by Chi-Square, Kruskal-Wallis, and Mann-Whitney tests (α = 0.05). RESULTS: In total, 3.883 records relative to return periodicity were analyzed. The final sample consisted of 900 restorations from 479 patients. The majority were females, aged between 31 and 60. In total, 256 failures were reported (success rate = 78%), showing an annual failure rate of 2.05%. The main reasons for failures were restoration replacement (55.5%), endodontics (21.9%), prosthetics (14.5%) and extraction (8.2%). There was a higher risk of failure in restorations involving three or more surfaces (p = 0.000) and in patients over 60 years (p < 0.001). In females (p = 0.030), molars (p = 0.044), and maxillary teeth (p = 0.038) failed in a shorter time. CONCLUSIONS: Resin composite restorations placed in permanent posterior teeth by dental students had high survival rates. The main reason for failure was the replacement of restorations. The age group and the number of restored surfaces significantly affected the success of the restorations. CLINICAL RELEVANCE: The electronic health records over 12 years showed that 78% of the resin restorations in posterior teeth placed by dental students were successful for a minimum of five years.

Pomegranate extract on eroded dentin: antioxidant action, bond strength and morphology of the adhesive interface after aging.

Objectives: This study aimed to evaluate the effect of pomegranate solution (Punica granatum) on eroded dentin through antioxidant action, shear bond strength (SBS) and interface morphology. Materials and Methods: The 10% pomegranate peel extract was prepared by the lyophilization method. Punicalagin polyphenol was confirmed by high-performance liquid chromatography. Antioxidant activity was evaluated by capturing the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. For the SBS, 48 dentin fragments were divided into sound or eroded, and subdivided according to the pretreatment (n = 12): water or P. granatum. The surfaces were restored with self-etch adhesive and a bulk-fill resin (Ecosite; DMG). The SBS was done immediately (24 hours) and after thermal cycling + water storage (12 months). For scanning electron microscopy, 48 dentin fragments (24 sound and 24 eroded) received the same treatments as for SBS (n = 6), and they were analyzed after 24 hours and 12 months. Results: The P. granatum had antioxidant action similar (p = 0.246) to the phenolic standard antioxidants. After 24 hours, eroded dentin had lower SBS than sound dentin (p < 0.001), regardless of the pretreatment. After 12 months, P. granatum maintained the SBS of sound dentin (13.46 ± 3.42 MPa) and eroded dentin (10.96 ± 1.90 MPa) statistically similar. The lowest values were found on eroded dentin treated with water (5.75 ± 1.65 MPa) (p < 0.001). P. granatum on eroded dentin caused peritubular demineralization and hybrid layer with resin tags. Conclusions: The pomegranate extract had antioxidant action and preserved the adhesive interface of the eroded dentin.

Comparing deep learning and pathologist quantification of cell-level PD-L1 expression in non-small cell lung cancer whole-slide images.

Programmed death-ligand 1 (PD-L1) expression is currently used in the clinic to assess eligibility for immune-checkpoint inhibitors via the tumor proportion score (TPS), but its efficacy is limited by high interobserver variability. Multiple papers have presented systems for the automatic quantification of TPS, but none report on the task of determining cell-level PD-L1 expression and often reserve their evaluation to a single PD-L1 monoclonal antibody or clinical center. In this paper, we report on a deep learning algorithm for detecting PD-L1 negative and positive tumor cells at a cellular level and evaluate it on a cell-level reference standard established by six readers on a multi-centric, multi PD-L1 assay dataset. This reference standard also provides for the first time a benchmark for computer vision algorithms. In addition, in line with other papers, we also evaluate our algorithm at slide-level by measuring the agreement between the algorithm and six pathologists on TPS quantification. We find a moderately low interobserver agreement at cell-level level (mean reader-reader F1 score = 0.68) which our algorithm sits slightly under (mean reader-AI F1 score = 0.55), especially for cases from the clinical center not included in the training set. Despite this, we find good AI-pathologist agreement on quantifying TPS compared to the interobserver agreement (mean reader-reader Cohen's kappa = 0.54, 95% CI 0.26-0.81, mean reader-AI kappa = 0.49, 95% CI 0.27-0.72). In conclusion, our deep learning algorithm demonstrates promise in detecting PD-L1 expression at a cellular level and exhibits favorable agreement with pathologists in quantifying the tumor proportion score (TPS). We publicly release our models for use via the Grand-Challenge platform.

Assessing push-out bond strength in re-irradiated teeth: Universal resin cement performance in self-etch and self-adhesive modes.

OBJECTIVES: To investigate the effect of cumulative doses of radiation on the pushout bond strength (BS) of a universal resin cement used in the self-etch (SE) and self-adhesive (SA) modes to the intraradicular dentin. MATERIALS AND METHODS: Forty-eight human teeth were distributed into three groups (n = 16) according to the radiation therapy dose (RT): NoRT (no-radiotherapy), 70RT (70 Gy), and 70 + 70RT (70 Gy + 70 Gy). The teeth were redistributed into two subgroups (n = 8), according to the adhesive mode: SE (NoRT-SE, 70RT-SE, and 70 + 70RT-SE) and SA (NoRT-SA, 70RT-SA, and 70 + 70RT-SA). Data were statistically compared after BS test (ANOVA, Tukey's post hoc test, and Fisher's exact test). RESULTS: In the SA mode, BS was significantly higher in nonirradiated teeth compared with 70RT and 70 + 70RT (p < 0.0001). There were no significant differences between SE and SA modes in nonirradiated teeth (p = 0.14). In the 70RT group, SE mode increased BS compared with SA mode (p < 0.0001). Most specimens had adhesive and mixed failures in SA and SE modes, respectively. CONCLUSIONS: The universal resin cement in the SE mode had greater BS to the irradiated dentin. When teeth were re-irradiated, the universal resin cement had similar performance in terms of BS, regardless of the adhesive approach. CLINICAL SIGNIFICANCE: There is no research establishing a correlation between radiotherapy and its impact on the BS of a universal resin cement used in SE and SA modes to intraradicular dentin.

Probing Antioxidant-Related Properties for Phenolic Compounds.

In this work, properties related to antioxidant-potential mechanisms (such as the bond dissociation enthalpy, BDE, for the homolytic cleavage of the O-H bond and ionization energies, IEs) were determined for phenol, pyrocatechol, and gallic acid (GA). Both the protonated and deprotonated forms of GA were investigated. The Feller-Peterson-Dixon (FPD) composite method was employed with a variety of computational approaches, i.e., density functional theory, Möller-Plesset perturbation theory, and coupled-cluster-based methods, in combination with large correlation consistent basis sets with extrapolation to the complete basis set limit and consideration of core electron correlation effects. FPD results were compared to experimental and computational data available in the literature, presenting good agreement. For example, the FPD BDE (298 K) obtained for phenol, which was based on valence-correlated MP2/CBS calculations with contributions from correlating all electrons, was determined to be 87.56 kcal/mol, a value that is 0.42 kcal/mol lower than the result obtained in the most recent experiments, 87.98 ± 0.62. Calibration against coupled-cluster calculations was also carried out for phenol. We expect that the outcomes gathered here may help in establishing a general protocol for computational chemists that are interested in determining antioxidant-related properties for phenolic compounds with considerable accuracy as well as to motivate future IE measurements (particularly for GA) to be accomplished in the near future.

Physicochemical and mechanical properties of preheated composite resins for luting ceramic laminates.

This study analyzed and compared the physicochemical and mechanical properties of preheated resin composite with light-cured resin cement for luting indirect restorations. 210 specimens of resin cement/resin composite were prepared according to preheating treatment heated (Htd) or not (NHtd). Light-cured resin cement (Variolink Veneer, Ivoclar), and resin composite (Microhybrid-Z100, 3 M; Nanohybrid-Empress direct, Ivoclar; and Bulk fill-Filtek One, 3 M) were used (n = 10). Resin cement specimens were not preheated. The response variables were (n = 10): film thickness, microhardness, liquid sorption and solubility. Data were analyzed by 2-way ANOVA and Tukey HSD post-test (α = 0.05). Bulk fill NHtd resin had the highest film thickness values (p < 0.001). Microhybrid and nanohybrid Htd resins had the smallest thicknesses and did not differ from the cement (p > 0.05). The highest microhardness values were found for Bulk fill NHtd and Bulk fill Htd resins. The nanohybrid and microhybrid Htd resins showed the lowest microhardness values, with no difference in cement (p > 0.05). For liquid sorption, there was no significant difference between the groups (p = 0.1941). The microhybrid Htd resin showed higher solubility values than the other materials (p = 0.0023), but it did not differ statistically from resin cement (p > 0.05). Preheating composite resins reduced the film thickness. After heating, nanohybrid and Bulk fill resins retained stable microhardness, sorption, and solubility values.

A density functional theory benchmark on antioxidant-related properties of polyphenols.

In this work, we present a density functional theory benchmark on antioxidant-related properties for a series of six polyphenols that are well-known antioxidants: caffeic acid, cyanidin, ellagic acid, gallic acid, myricetin, and phloretin. Computations on the 24 O-H bond dissociation enthalpies (BDEs) and 6 ionization potentials (IPs) were performed using twenty-three exchange-correlation functionals combined with four different basis sets in the gas-phase, water, and methanol; calibration against the Domain-based Local Pair Natural Orbital CCSD(T) (DLPNO-CCSD(T)) approach was employed. Mean absolute deviation (MAD) as well as linear fitting results suggested the LC-PBE approach as the most suitable for O-H BDEs in the gas-phase. The LC-PBE, M06-2X, and M05-2X results presented the smallest MADs for O-H BDEs when compared to the reference, in water. The LC-PBE results had the smallest MADs for IPs in the gas-phase while M05-2X, M06-2X, LC-PBE, and LC-ωPBE exhibited the best results for MAD in water. We expect the outcomes from the present work will serve as general guidance for researchers working in the field.

Bovine serum albumin nanoparticles containing Poly (I:C) can enhance the neutralizing antibody response induced by envelope protein of Orthoflavivirus zikaense.

Since the Orthoflavivirus zikaense (ZIKV) has been considered a risk for Zika congenital syndrome development, developing a safe and effective vaccine has become a high priority. Numerous research groups have developed strategies to prevent ZIKV infection and have identified the domain III of the ZIKV envelope protein (zEDIII) as a promising target. Subunit antigens are often poorly immunogenic, necessitating the use of adjuvants and/or delivery systems to induce optimal immune responses. The subject of nanotechnology has substantial expansion in recent years in terms of research and applications. Nanoparticles could be used as drug delivery systems and to increase the immunogenicity and stability of a given antigen. This work aims to characterize and validate the potential of a vaccine formulation composed of domain zEDIII and bovine serum albumin nanoparticles containing polyinosinic-polycytidylic acid (NPPI). NPPI were uptake in vitro by immature bone marrow dendritic cells and histological analysis of the skin of mice treated with NPPI showed an increase in cellularity. Immunization assay showed that mice immunized with zEDIII in the presence of NPPI produced neutralizing antibodies. Through the passive transfer of sera from immunized mice to ZIKV-infected neonatal mice, it was demonstrated that these antibodies provide protection, mitigating weight loss, clinical or neurological signs induced by infection, and significantly increased survival rates. Protection was further substantiated by the reduction in the number of viable infectious ZIKV, as well as a decrease in inflammatory cytokines and tissue alterations in the brains of infected mice. Taken together, data presented in this study shows that NPPI + zEDIII is a promising vaccine candidate for ZIKV.

Multiplex Immunofluorescence Captures Progressive Immune Exhaustion with Advancing Penile Squamous Cell Cancer Stage.

Penile squamous cell carcinoma (PSCC) is a rare and deadly malignancy. Therapeutic advances have been stifled by a poor understanding of disease biology. Specifically, the immune microenvironment is an underexplored component in PSCC and the activity of immune checkpoint inhibitors observed in a subset of patients suggests immune escape may play an important role in tumorigenesis. Herein, we explored for the first time the immune microenvironment of 57 men with PSCC and how it varies with the presence of human papillomavirus (HPV) infection and across tumor stages using multiplex immunofluorescence of key immune cell markers. We observed an increase in the density of immune effector cells in node-negative tumors and a progressive rise in inhibitory immune players such as type 2 macrophages and upregulation of the PD-L1 checkpoint in men with N1 and N2-3 disease. There were no differences in immune cell densities with HPV status.

The Impact of Time From Diagnosis to Initiation of Chemotherapy on Survival of Patients With Newly Diagnosed Diffuse Large B-Cell Lymphoma in the Veterans Health Administration.

INTRODUCTION: Our retrospective study evaluates the impact of time from diagnosis to treatment (TDT) on outcomes of patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) treated within the Veterans Health Administration (VHA). METHODS: VHA patients diagnosed with DLBCL between 2011 and 2019 were included, while those with primary central nervous system lymphoma were excluded. The median overall survival and progression-free survival were estimated with the Kaplan-Meier method. Univariate, bivariate, and multivariable analyses were performed using the Cox proportional hazards model. The odds ratio for refractory outcomes was calculated using logistic regression. RESULTS: A total of 2448 patients were included. The median time from diagnosis to treatment of the cohort was 19 days. When comparing median progression-free survival, median overall survival, and the 2-year overall survival between the group that started treatment within 1 week and each of the other groups individually, there was a significant difference favoring improved survival in all groups with a TDT longer than 1 week (P < .0001). These patients also had a lower odds ratio for refractory outcomes. On multivariable analysis, TDT remained an independent prognostic factor. CONCLUSION: Our study shows that a TDT equal to or less than 1 week is associated with adverse clinical factors, worse outcomes, and response in DLBCL, even after adjusting for multiple known poor prognostic factors. This was the first time that response to first-line therapy was correlated to time to treatment. Our findings support ongoing efforts to improve currently standardized prognostic tools and the incorporation of TDT into clinical trials to avoid selection bias.

Acute effects of foam rolling on ankle dorsiflexion and squat exercise patterns in extreme conditioning program practitioners: A randomized clinical trial.

BACKGROUND/OBJECTIVES: Joint and muscle overloads commonly occur in extreme conditioning programs (ECP), which require great physical fitness for their practice. For its execution, good functional performance, mobility and adequate movement patterns are required. The fascial system plays a fundamental role in performance in ECP and one of the techniques used to improve joint mobility and movement pattern is the self-myofascial release using a foam roller (FR). Our objective of this study was to evaluate the effect of FR in ankle dorsiflexion (DF) range of motion (ROM), assessed with the Lunge Test, and also in the squat movement pattern, assessed using the Technique smartphone application, in ECP practitioners. METHODS: The study was carried out with 18 ECP practitioners who practiced for over four months and had a mean age of 30.94 years. The participants were randomized and allocated into two groups: control and intervention. The FR was self-applied bilaterally in the sural triceps region for 90 seconds. Tests to assess DF ROM and squat movement pattern were applied before and immediately after using FR (intervention group) or after three-minute rest (control group). RESULTS: The use of the FR promoted an immediate increase in ankle DF ROM during the Lunge Test and during the squat and a decrease in dynamic knee valgus during the squat. CONCLUSION: The FR can be used as a tool for an acute increase in DF ROM and a decrease in dynamic knee valgus, having a positive impact in improving movement patterns.

Impact of access cavities on root canal preparation, restorative protocol quality, and fracture resistance of teeth.

The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.