Background and aimBioceramics are ceramic compounds obtained both in situ and in vivo, by various chemical processes. Bioceramics exhibit excellent biocompatibility due to their similarity with biological materials, like hydroxyapatite. Bioceramics and multi-substituted hydroxyapatite or similar compounds have the ability to induce a regenerative response in the organism.The aim of this paper is to make a literature review on the main bioceramic materials currently used in endodontics and on their specific characteristics.MethodsWe conducted a search in the international databases (PubMed), to identify publications in the last 10 years, using the following key words: “bioceramics endodontics”, “bioceramic endodontic cement”, “bioceramic sealer” and “direct pulp capping bioceramic”.ResultsCommonly used endodontic sealers (e.g., containing zinc oxide, calcium hydroxide and a resin) have a long tradition in scientific research and clinical use in endodontics. For specific cases, like root resorptions, perforations, apexification, and retrograde fillings, new biocompatible materials were developed in order to improve the clinical outcome: ProRooT MTA (Dentsply Company, Germany); Biodentine (Septodont, France); Endosequence BC sealer (Brassler, SUA); Bioaggregate (IBC, Canada); Generex A (Dentsply Tulsa Dental Specialties, USA).ConclusionThe studies are generally in favor of bioceramic materials even if there are not many products available on the market for endodontic use. As more products are launched and more research is performed regarding these materials, we will provide more reliable data on clinical outcome.

ABSTRACT. In order to obtain a low crystalline nanohydrxyapatite (HAP), suitable for biomedical application, a new synthesis procedure was developed, based on the aqueous precipitation method, at room temperature, without any additives. Accordingly, lyophilized HAP powders, both calcined and non calcined, were prepared, and characterized by XRD, TEM and AFM imaging, FTIR spectroscopy, zeta potential and BET measurements. The results confirmed HAP as the only phase present. The high porosity of this nanomaterial is attained. The nanoparticle size and shape as well as the crystallinity degree of the obtained HAP samples were also determined.

Endodontic cement based on calcium silicate has been the focus of many studies. However, the quality of resulted endodontic cement needs improvement. This paper focuses on endodontic cement obtained from Portland cement enriched with two types of hydroxyapatite, simple and doped with 5% Zn. Hydroxyapatites were synthesized using a wet precipitation method and investigated by X-ray diffraction, FTIR, TEM and AFM. From a structural point of view, both hydroxyapatites were obtained in a single crystalline phase, containing particles in the nanometric range, as judged by XRD, TEM and AFM. FTIR analysis presents O-H and P-O bands specific to those in pure hydroxyapatite, confirming a hydroxyapatite lattice in both materials. Several experimental compositions of commercial Portland cement mixed with hydroxyapatite were prepared. The influence of stoichiometric and Zn doped hydroxyapatite on the resulted endodontic cement was observed in the setting time. The setting time for both cements decreased exponentially at both temperatures (22 ⁰C and 37 ⁰C). The normal consistency water remains constant for all experimented slurries.

The purposes of the study were to evaluate the influence of the sealer’s chemical composition on the interfacial strength between root canal dentin and root filling material, for two different classes of endodontic sealers, and to assess their failure modes. Methods: Forty extracted single-rooted teeth were randomly divided into four groups using the following endodontic sealers: RealSeal SE and Resilon (RSSE); EndoSequence BC sealer and BC Point (EBCS); Endoseal MTA and gutta-percha (EDS); Bioroot RCS and gutta-percha (BRS). Teeth were embedded in acrylic resin, and the roots were sectioned horizontally into 1 mm slices. For each slice, the perimeter was measured. A push-out test was performed using an Instron universal testing machine. For each sample, bond strength was calculated. Specimens were examined by SEM investigation in order to analyze the dentin–sealer–core interface. Results were assessed using analysis of variance (ANOVA) and Tukey and Bonferroni test. Results: Statistical analysis revealed that EDS and gutta-percha had significantly higher resistance to dislodgement compared to the other three groups (p < 0.05). EBCS and BC Point showed significantly greater push-out bond strength values compared to RSSE and Resilon (p < 0.05). Conclusions: Bioceramic endodontic sealers showed a higher bond strength to root dentin than methacrylate resin-based endodontic sealer.

Photography is a major component of present art. It has applications in arts, in sciences and mainly health sciences, in social interaction. The evolution of photography since its advent 200 years ago relied and was dependent on the knowledge of chemistry. This is a review of the chemical techniques used in the recording and reproduction of photographs and of its applications. In the last two centuries, numerous chemical substances: inorganic, organic and polymeric, influenced the aspect and quality of the photographic techniques and of photographs. Teaching photography requires knowledge of chemistry, while chemistry education needs knowledge of esthetics as offered by photography.