Cigarette Smoking Effect on Microhardness and Flexural Properties of Denture Base Resins

ABSTRACT Objective: To identify the tobacco effect on flexural properties and the microhardness of three acrylic resins. Material and Methods: Three resins were tested: two thermo-polymerizable acrylic resins (RMB 20 and BMS 014) and one autopolymerized acrylic resin. The 3-point bending and microhardness tests were carried out with a universal tensile-compression machine and a micro-Vickers hardness tester. The acrylic resin specimens have been exposed for 21 days to cigarette smoke in a smoking room. Their mechanical strength was compared to unexposed samples. Statistical analysis was performed using the data processing software SPSS Statistics 21.0. Results: The flexural properties of the resins were affected by cigarette smoke only in the case of Major Base 20® (drop in strength with p= 0.02; 0.6; 0.7 and in elastic modulus with p= 0.86; 0.74 and 0.85 for Major Base 20®, BMS 014® and Major Repair®). The cigarette smoke affected significantly microhardness for all groups (p<0.001). Conclusion: Cigarette smoking does not affect the flexural properties of the acrylic resin (BMS 014® and Major Repair® unlike Major Base 20®), but it does reduce the microhardness.

Assessment of Pharmacokinetics, Toxicity, and Biodistribution of a High Dose of Titanate Nanotubes Following Intravenous Injection in Mice: A Promising Nanosystem of Medical Interest.

Titanate nanotubes (TiNTs) produced by the static hydrothermal process present a promising nanosystem for nanomedicine. However, the behavior of these nanotubes in vivo is not yet clarified. In this work, for the first time, we investigated the toxicity of these materials, their pharmacokinetic profile, and their biodistribution in mice. A high dose of TiNTs (45 mg/kg) was intravenously injected in mice and monitored from 6 h to 45 days. The histological examination of organs and the analysis of liver and kidney function markers and then the inflammatory response were in agreement with a long-term innocuity of these nanomaterials. The parameters of pharmacokinetics revealed the rapid clarification of TiNTs from the bloodstream after 6 h of the intravenous injection which then mainly accumulated in the liver and spleen, and their degradation and clearance in these tissues were relatively slow (>4 weeks). Interestingly, an important property of these materials is their slow dissolution under the lysosome acid environment, rendering them biodegradable. It is noteworthy that TiNTs were directly eliminated in urine and bile ducts without obvious toxicity in mice. Altogether, all these typical in vivo tests studying the TiNT pharmacokinetics, toxicity, and biodistribution are supporting the use of these biocompatible nanomaterials in the biomedical field, especially as a nanocarrier-based drug delivery system.

Outcome of Root Canal Treatment of Necrotic Teeth with Apical Periodontitis Filled with a Bioceramic-Based Sealer.

INTRODUCTION: Apical periodontitis is among the most common pathologies in endodontics. The treatment of apical periodontitis has always been an important occupation in the modern practice of endodontics, and the failure has been associated with nonhermetic root canal filling. With that in mind, bioceramic-based sealers have been incorporated into endodontic practice. The purpose of this study was to evaluate the outcome of nonsurgical root canal treatment (RCT), using a single-cone and Bioroot RCS filling of necrotic teeth with apical periodontitis. MATERIALS AND METHODS: This follow-up study included patients treated in the department of Restorative Dentistry and Endodontics in the Dental Clinic of Monastir, from January 2018 to December 2019. The study intended to include all adult patients presenting a symptomatic or asymptomatic apical periodontitis. Once the diagnosis was performed, the patients were divided into two groups: a one-session treatment group and a two-session treatment group. All cases were obtured with BioRoot using a single-cone technique with a minimum of a 6-month recall. At 6-month follow-ups, teeth were classified as healed, healing (success), or not healed (failure), based on clinical and radiographic findings. RESULTS: Twelve patients met the inclusion criteria, six patients per group. Seven patients returned for follow-ups. At 6-month follow-ups, the overall success rate was 100%, with 57.1% determined to be "healed" and 42.8% determined to be "healing." All the PAI scores decreased compared to the baseline situation. CONCLUSION: The results obtained showed the contribution of BioRoot RCS in the healing of periapical lesions. Accordingly, bioceramic-based sealers seem to optimize the prognosis of root canal treatments.

Shear Bond Strength of Three Composite Resins to Fluorosed and Sound Dentine: In Vitro Study.

INTRODUCTION: This in vitro study compared the shear strength of three composite resin systems to fluorosed and normal dentin. METHODS: Silorane FiltekTM P90, FiltekTMZ250 XT in combination with the adhesive system AdperTM Single bond 2, and Amelogen® Plus in association with Peak Universal Bond® were tested. Fifteen normal and 15 fluorosed dentine disks were prepared per material. The shear bond strength test was performed using a universal machine. RESULTS: One-way ANOVA revealed significant differences in bond strength between the tested composite resins. All tested materials had significantly different adhesion at the fluorosed and the nonfluorosed interface. FiltekTM Z250 XT and Silorane had lower adhesion values to fluorosed than to normal dentin. In contrast, Amelogen® Plus presented a better average resistance at the fluorosed interface. CONCLUSION: Amelogen® Plus presented a better average shear bond strength on the fluorosed dentine. FiltekTMZ250 XT showed the best adhesion forces and shear bond strength with sound dentine. Further studies are needed to better understand the sealing of these systems.

Sealing Ability of Endodontic Cements: An In Vitro Study.

The root canal system must be obturated using a hermetic seal to prevent the penetration of microorganisms and bacterial toxins into the endodontic system. The principles of adhesive dentistry have been increasingly used in endodontics. In fact, resin-based sealers are increasingly used. The objective of this study was to evaluate, in vitro, the sealing ability of resin cement in comparison with calcium hydroxide-based cement. Materials and Methods. Eighty root canals were prepared with the Tilos system and were randomly divided into four groups according to the filling material. The best combination was evaluated on the basis of its sealing ability. The dye infiltration degree was evaluated using both a stereomicroscope after diaphanization and the dye rise test. Results. A significant difference was observed between the four obturation systems with regard to the number of infiltrated walls (p=0.014) and the infiltration depth (p=0.025). The group of teeth obturated with EndoREZ® and EndoREZ® gutta cones differ significantly from the group obturated with EndoREZ® cement and gutta-percha cones in terms of apical sealing (p=0.011). A significant difference was also observed between the group of teeth obturated using EndoREZ® gutta cones and EndoREZ® cement and the group of teeth obturated with EndoREZ® cement (p=0.026). Conclusion. When used with EndoREZ® gutta cones, EndoREZ® cement showed the best sealing ability, particularly in the apical region. When used with gutta-percha cones, Acroseal and EndoREZ® cements exhibited similar sealing abilities.

Vital laser-activated teeth bleaching and postoperative sensitivity: A systematic review.

OBJECTIVE: This systematic review investigated the effect of vital laser-activated tooth bleaching regarding efficiency and postoperative sensitivity. The search for articles was conducted on Medline (PubMed) database. The following keywords were used: "Lasers" [Mesh] and "Tooth bleaching" [Mesh]. Using the Boolean operator "AND," the following Boolean equation was formulated: ("Lasers" [MeSH] AND "Tooth bleaching" [MeSH]). MATERIALS AND METHODS: Inclusion criteria were as follow: clinical trials in English or French available in full text. Article search was limited to the ones published between 2007 and 2019. RESULTS: A total of 12 articles fulfilled the inclusion criteria. The quality assessment of trials included was undertaken independently as part of data extraction process. A JADAD score was attributed to each paper. CONCLUSION: A marked color change was noted for patients undergoing light-activated bleaching independently of the bleaching agent. Regarding sensitivity, the results of the various studies proved controversial. CLINICAL SIGNIFICANCE: Laser activation of the bleaching agent promotes the efficiency of the treatment but does not reduce postoperative sensitivity.