Multifunctional Dental Adhesives Formulated with Silane-Coated Magnetic Fe3O4@m-SiO2 Core-Shell Particles to Counteract Adhesive Interfacial Breakdown.

The process of bonding to dentin is complex and dynamic, greatly impacting the longevity of dental restorations. The tooth/dental material interface is degraded by bacterial acids, matrix metalloproteinases (MMPs), and hydrolysis. As a result, bonded dental restorations face reduced longevity due to adhesive interfacial breakdown, leading to leakage, tooth pain, recurrent caries, and costly restoration replacements. To address this issue, we synthesized and characterized a multifunctional magnetic platform, CHX@SiQuac@Fe3O4@m-SiO2, to provide several beneficial functions. The platform comprises Fe3O4 microparticles and chlorhexidine (CHX) encapsulated within mesoporous silica, which was silanized by an antibacterial quaternary ammonium silane (SiQuac). This platform simultaneously targets bacterial inhibition, stability of the hybrid layer, and enhanced filler infiltration by magnetic motion. Comprehensive experiments include X-ray diffraction, FT-IR, VSM, EDS, N2 adsorption-desorption (BET), transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, and UV-vis spectroscopy. Then, CHX@SiQuac@Fe3O4@m-SiO2 was incorporated into an experimental adhesive resin for dental bonding restorations, followed by immediate and long-term antibacterial assessment, cytotoxicity evaluation, and mechanical and bonding performance. The results confirmed the multifunctional nature of CHX@SiQuac@Fe3O4@m-SiO2. This work outlined a roadmap for (1) designing and tuning an adhesive formulation containing the new platform CHX@SiQuac@Fe3O4@m-SiO2; (2) assessing microtensile bond strength to dentin using a clinically relevant model of simulated hydrostatic pulpal pressure; and (3) investigating the antibacterial outcome performance of the particles when embedded into the formulated adhesives over time. The results showed that at 4 wt % of CHX@SiQuac@Fe3O4@m-SiO2-doped adhesive under the guided magnetic field, the bond strength increased by 28%. CHX@SiQuac@Fe3O4@m-SiO2 enhanced dentin adhesion in the magnetic guide bonding process without altering adhesive properties or causing cytotoxicity. This finding presents a promising method for strengthening the tooth/dental material interface's stability and extending the bonded restorations' lifespan.

3D cone-beam C.T. imaging used to determine the effect of disinfection protocols on the dimensional stability of full arch impressions.

AIM: This study aimed to investigate the dimensional stability of irreversible hydrocolloid and polyvinylsiloxane (P.V.S.) impressions after exposure to four commercial disinfectants using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Two different impression materials were tested: irreversible hydrocolloid and P.V.S. Four disinfection solutions were applied: BirexSE, Opti-Cide3, COEfect MinuteSpray, and CaviCide Spray. Distilled water was used as a control group. Each solution remained in contact with the impression for 5 min. Additional contact time of 5 min compromises time for scanning. The materials were evaluated for dimensional stability after the impression of a maxillary complete edentulous template via CBCT before and after being in contact with the disinfectant agents. Measurements were assessed on the digital models from A-B, B-C, and C-A points. Paired analyses (Wilcoxon Signed Rank test or paired Student's t-test) were used to analyze each measurement before and after the contact with the disinfectant agents. The variance for each measurement was also analyzed via a one-way analysis of variance or Kruskal-Wallis. RESULTS: Overall, there were no statistical differences among the points measurements in the irreversible hydrocolloid or P.V.S. between initial and final assessments (p > 0.05). The used disinfectant agents in this study did not influence each measurement's variation on irreversible hydrocolloid or P.V.S. (p > 0.05). All agents showed an effect on the dimensional stability of both impression materials. The differences in the three dimensions ranged between 0.34 and 1.54%. CONCLUSION: Within 10 min of removing the impression from the master cast, is study's findings indicated that the four commercially available disinfectants did not influence the dimensional stability of irreversible hydrocolloid or P.V.S. Further studies should be performed to elucidate the antimicrobial effect of these solutions applied as a spray on the surface of irreversible hydrocolloid and P.V.S. impressions.

Microfiltración apical entre dos cementos de obturación: biocerámico y resinoso en premolares unirradiculares preparadas con protaper, y obturadas con condensación lateral / Apical microfiltration between two filling cements: bioceramic and resinous in unirradicular premolars prepared with protaper and sealed with lateral condensation

Resumen Objetivo: Comparar in vitro la microfiltración apical en premolares unirradiculares obturados con cemento a base de resina epóxica y cemento biocerámico. Método: 40 piezas dentales unirradiculares fueron seleccionadas y divididas en dos grupos para ser obturadas esperando el tiempo de fraguado de acuerdo con las instrucciones del fabricante. El grupo A se obturó con cemento biocerámico Endosequence y, el grupo B, con cemento a base de resina epóxica AH-Plus: posteriormente los dos grupos fueron sellados con barniz de uñas hasta 3mm de la parte apical, luego se colocaron las muestras en la incubadora a 37ºC. Ambos fueron sometidos a 750 ciclos de termociclado, para reproducir el ambiente parecido a la cavidad oral. Para análisis de microfiltración se utilizó el método de difusión del colorante, se sumergieron en azul de metileno al 2 % por 6 días, posteriormente los especímenes fueron sometidos en una bomba de vacío. Los dientes fueron cortados longitudinalmente para ser evaluadas mediante el estereomicroscopio. El análisis estadístico fue hecho mediante T-Student y Chi-Cuadrado. Resultados: El grupo A corresponde a Endosequence obtuvo una medida de 0,55mm y el grupo B corresponde a AH-Plus 1,20mm con un estimado de significancia de p=0,013. Conclusión: El análisis de ambos cementos de obturación demostró que Endosequence posee menor microfiltración apical que AH-Plus.

Abstract Aim: To compare in vitro by the stereomiscroscope the lesser apical microfiltration in uniradicular premolars, between the cement based on Epoxy Resin and Bioceramic cement. Method: The study was performed on 40 uniradicular dental pieces divided into two groups, the samples were prepared using the protaper system and the obturation was performed using the lateral condensation technique, the first group was sealed withEndosequence bioceramic cement and the second group with Cement based on AH-Plus epoxy resin, then sealed with nail varnish up to 3mm from the apical part, then the samples were placed in the incubator at 37ºC, waiting for the set time corresponding to each group according to the manufacturer's instructions . The two groups of the present study were submitted to 750 cycles of thermocycling, to provide an environment similar to the oral cavity, then longitudinal cuts were made to the samples. The microfiltration was evaluated using the dye diffusion method, immersed in 2% methylene blue for 6 days, then the specimens were subjected to a vacuum pump. The teeth were cut longitudinally to be evaluated by the stereomicroscope. The statistical analysis was through T-Student and Chi-Square. Results: Group A corresponds to Endosequence obtained a mean of 0,55mm and Group B corresponds to AH-Plus 1,20mm with an estimated significance of p = 0,013. Conclusion: Both obturation cements have significant differences, therefore Endosequence has less apical microfiltration than AHPlus.

Ionic liquid as antibacterial agent for an experimental orthodontic adhesive.

OBJECTIVE: The aim of this study was to formulate and evaluate experimental orthodontic adhesives with different concentrations of 1-n-butyl-3-methylimidazoilium bis(trifluoromethanesulfonyl)imide (BMIM.NTf2). METHODS: The experimental orthodontic adhesives were formulated with methacrylate monomers, photoinitiators and silica colloidal. The ionic liquid BMIM.NTf2 was synthesized and characterized. BMIM.NTf2 was added at 5 (G5%), 10 (G10%) and 15 (G15%) wt.%. One group contained no BMIM.NTf2 to function as control (GCtrl). The adhesives were evaluated for polymerization kinetics, degree of conversion (DC), Knoop hardness and softening in solvent, ultimate tensile strength (UTS), shear bond strength (SBS), thermogravimetric analysis (TGA), antibacterial activity and cytotoxicity. RESULTS: BMI.NTf2 showed the characteristic chemical peaks. The polymerization kinetics were different among the groups. G10% and G15% showed higher DC (p < 0.05). G5% and GCtrl had no differences for softening in solvent (p > 0.05). There were no differences for UTS (p > 0.05) and SBS (p > 0.05). TGA showed one different peak for G15%. All groups with BMIM.NTf2 showed antibacterial activity compared to GCtrl (p < 0.05) without cytotoxicity (p > 0.05). SIGNIFICANCE: To reduce biofilm formation around brackets and to prevent demineralization at susceptible sites, materials have been developed with antibacterial properties. In this study, a new experimental orthodontic adhesive was formulated with an imidazolium ionic liquid (BMIM.NTf2) as antibacterial agent. The incorporation of 5 wt.% of ionic liquid decreased biofilm formation without affecting the physico-chemical properties and cytotoxicity of an experimental orthodontic resin.

Comparación in vitro del sellado apical entre dos sistemas de obturación termoplastificada: Guttacore y E&Q Master / In vitro comparison of the apical seal between two thermoplastic filling systems: Guttacore and E&Q Master

Objetivo: Comparar el sellado apical in vitro de los sistemas de obturación termoplastificada, GuttaCore® y E&Q Master®, desde la perspectiva de microfiltración. Métodos: Cuarenta piezas unirradiculares se instrumentaron con sistema rotatorio e irrigaron con hipoclorito de sodio al 2,5% y EDTA al 17%. Las muestras se dividieron en dos grupos (n=20); se obturaron y colocaron en estufa incubadora a 37°C y 100% de humedad durante 3 días. Cada muestra se cubrió con barniz de colores excepto 3 mm apicales para ser sumergidas en azul de metileno al 2% por 3 días, y centrifugados por 20 min a 3000 rpm. Las muestras se lavaron y fracturaron axialmente para su análisis, mediante fotografías, en el estereomicroscopio. Para el análisis de datos se utilizó la prueba t de Student con un nivel de significancia del 5%. Resultados: Los valores medios de microfiltración fueron 0,660 mm y 0,825 mm para GuttaCore® y E&Q Master®, respectivamente, no encontrándose diferencias estadísticamente significativas entre ellas (p=0,525). Conclusión: GuttaCore® y E&Q Master® son sistemas de obturación que ofrecen un buen sellado apical no existiendo diferencia entre ellos. Palabras clave: EDTA; Gutapercha; Hipoclorito de Sodio; Microfiltración.

Objective: Compare in vitro the apical seal of thermoplastic filling systems, GuttaCore®and E&Q Master®, from the perspective of microfiltration. Methods: Forty single-rooted teeth were instrumented with rotary system and irrigated with 2.5% sodium hypochlorite and 17% EDTA. The samples were divided into two groups (20 for each system); sealed and placed in the incubator at 37°C and 100% humidity for 3 days. Each sample was covered with colored varnish except the last 3 apical millimiters to be immersed in 2% methylene blue for 3 days and centrifuged for 20 min at 3000 rpm. The samples were washed and fractured axially for their analysis in the stereomicroscope by means of photographs. For the data analysis we used the t Studenttest with a level of significance of 5%.Results: The mean microfiltration values were 0.660 mm and 0.825 mm for GuttaCore and E&Q Master respectively, no statistically significant differences were found between them (p=0.525). Conclusion: GuttaCore and E&Q Master are seal systems that offer good apical sealing, there is no difference between them. Keywords: EDTA; Gutta-Percha; Microfiltration; Sodium Hypochlorite.