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Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics.

ABSTRACT: The bioactivity of a series of fluoride-containing sodium-free calcium and strontium phosphosilicate glasses has been tested in vitro. Glasses with high fluoride content were partially crystallised to apatite and other fluoride-containing phases. The bioactivity study was carried out in Tris and SBF buffers, and apatite formation was monitored by XRD, FTIR and solid state NMR. Ion release in solutions has been measured using ICP-OES and fluoride-ion selective electrode. The results show that glasses with low amounts of fluoride that were initially amorphous degraded rapidly in Tris buffer and formed apatite as early as 3 h after immersion. The apatite was identified as fluorapatite by 19F MAS-NMR after 6 h of immersion. Glass degradation and apatite formation was significantly slower in SBF solution compared to Tris. On immersion of the partially crystallised glasses, the fraction of apatite increased at 3 h compared to the amount of apatite prior to the treatment. Thus, partial crystallisation of the glasses has not affected bioactivity significantly. Fast dissolution of the amorphous phase was also indicated. There was no difference in kinetics between Tris and SBF studies when the glass was partially crystallised to apatite before immersion. Two different mechanisms of apatite formation for amorphous or partially crystallised glasses are discussed.

SUBMITTER: Chen X

PROVIDER: S-EPMC5456181 | biostudies-other | 2014 Jul

REPOSITORIES: biostudies-other

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Project description:BackgroundGingivitis is driven by plaque accumulation and, if left untreated, can progress to irreversible periodontitis. For many, the mechanical action of toothbrushing does not achieve adequate plaque control. The aim of this study was to investigate whether twice-daily use of a toothpaste containing 0.2% high molecular weight (HMW) sodium hyaluronate with 67% sodium bicarbonate and 0.221% sodium fluoride (experimental toothpaste) could improve gingival health compared with a regular fluoride toothpaste (negative control). The study also assessed whether the experimental toothpaste could provide additive gingival health benefit over a toothpaste containing only 67% sodium bicarbonate and 0.221% sodium fluoride (positive control).MethodsThis was a single-center, examiner-blinded, randomized, clinical study in healthy adults with mild-to-moderate gingivitis. At baseline, after abstaining from toothbrushing for 12 h, prospective participants underwent oral soft tissue (OST) and oral hard tissue examination followed by assessments for gingival inflammation (Modified Gingival Index [MGI]), gingival bleeding (Bleeding Index [BI]), and supra-gingival plaque (Turesky Plaque Index [TPI]). Eligible participants were stratified by gender and baseline number of bleeding sites (low: <45; high: ≥45 bleeding sites). Following randomization, participants underwent prophylactic dental treatment. Participants received a full OST examination, MGI, BI and TPI assessments after 3 days, 1, 2 and 6 weeks of product use.ResultsIn total, 110 participants were screened for study entry and all were randomized to receive one of three toothpastes (experimental: sodium hyaluronate, sodium bicarbonate, sodium fluoride; positive control: sodium bicarbonate, sodium fluoride; negative control: regular fluoride toothpaste). For all measures, significant improvements were observed in participants receiving either sodium bicarbonate-containing toothpaste (experimental or positive control) compared with the regular fluoride toothpaste (negative control) at week 6. No significant difference was observed in any assessment or visit comparing the experimental toothpaste with the positive control.ConclusionsBoth the experimental and the positive control toothpastes demonstrated clinically relevant improvements in gingival health compared with a regular fluoride toothpaste (negative control). However, no additional gingival health improvement was observed for the experimental toothpaste compared with the positive control, therefore, no additional gingival health benefit can be attributed to the inclusion of sodium hyaluronate in this formulation.Trial registrationClinicalTrials.gov Identifier: NCT04737538 (04/02/2021).

Project description:The discovery of bioactive glasses (BGs) in the late 1960s by Larry Hench et al. was driven by the need for implant materials with an ability to bond to living tissues, which were intended to replace inert metal and plastic implants that were not well tolerated by the body. Among a number of tested compositions, the one that later became designated by the well-known trademark of 45S5 Bioglass® excelled in its ability to bond to bone and soft tissues. Bonding to living tissues was mediated through the formation of an interfacial bone-like hydroxyapatite layer when the bioglass was put in contact with biological fluids in vivo. This feature represented a remarkable milestone, and has inspired many other investigations aiming at further exploring the in vitro and in vivo performances of this and other related BG compositions. This paradigmatic example of a target-oriented research is certainly one of the most valuable contributions that one can learn from Larry Hench. Such a goal-oriented approach needs to be continuously stimulated, aiming at finding out better performing materials to overcome the limitations of the existing ones, including the 45S5 Bioglass®. Its well-known that its main limitations include: (i) the high pH environment that is created by its high sodium content could turn it cytotoxic; (ii) and the poor sintering ability makes the fabrication of porous three-dimensional (3D) scaffolds difficult. All of these relevant features strongly depend on a number of interrelated factors that need to be well compromised. The selected chemical composition strongly determines the glass structure, the biocompatibility, the degradation rate, and the ease of processing (scaffolds fabrication and sintering). This manuscript presents a first general appraisal of the scientific output in the interrelated areas of bioactive glasses and glass-ceramics, scaffolds, implant coatings, and tissue engineering. Then, it gives an overview of the critical issues that need to be considered when developing bioactive glasses for healthcare applications. The aim is to provide knowledge-based tools towards guiding young researchers in the design of new bioactive glass compositions, taking into account the desired functional properties.

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Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics.

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