Bioactivity assessment of bioactive glasses for dental applications: A critical review

Graphical abstract

Highlights

  • Factors that influence the level of bioactivity.

  • Significance of ‘bioactivity’ in the scope of bioactive glasses.

  • Relevance of classification methodologies to assess bioactive properties and to define their limits.

Abstract

Objective

In the context of minimally invasive dentistry and tissue conservation, bioactive products are valuable. The aim of this review was to identify, clarify, and classify the methodologies used to quantify the bioactive glasses bioactivity.

Methods

Specific search strategies were performed in electronic databases: PubMed, Embase, Cochrane Library, and Scopus. Papers were selected after a review of their title, abstract, and full text. The following data were then examined for final selection: BAG investigated, objectives, criteria, methods, and outcomes.

Results

Sixty-one studies published from 2001 to 2019, were included. The bioactivity of BAG can be evaluated in vitro in contact with solutions, enamel, dentin, or cells. Other studies have conducted in vivo evaluation by BAG contact with dentin and dental pulp. Studies have used various analysis techniques: evaluation of apatite with or without characterization or assessment of mechanical properties. Reprecipitation mechanisms and pulp cell stimulation are treated together through the term ‘bioactivity’.

Significance

Based on these results, we suggested a classification of methodologies for a better understanding of the bioactive properties of BAG. According to all in vitro studies, BAG appear to be bioactive materials. No consensus has been reached on the results of in vivo studies, and no comparison has been conducted between protocols to assess the bioactivity of other bioactive competitor products.

Introduction

Minerals ions can be removed from hydroxyapatite (HA) crystals of dental hard tissues, enamel and dentin, in case of erosive attack or carious lesions, this process is demineralization. Restoring these mineral ions to the HA crystals is called remineralization [ ]. The contemporary approach to caries management has drastically changed: operative strategies are abandoned in favor of biologic approaches based on individual caries risk, preventive dentistry, and non-invasive or minimal options [ , ]. Remineralization is a non-invasive treatment to preserve dental tissues after an acidic attack. In situ remineralization could occur with a dissolution reprecipitation process in enamel or in dentin, but new tertiary dentin could also be produced by stimulation of pulp cells [ ]. BAG are involved in both processes, but some studies have focused only on the first mechanism because others have focused on the second mechanism; thus, the term bioactivity for BAG remains unclear.

BAG were introduced in 1969 by professor Larry Hench (BAG 45S5), the composition was 45% silica (SiO 2 ) — 24.5% calcium oxide (CaO) — 24.5% sodium oxide (Na 2 O) — 6% phosphate (P 2 O 5 ). Initially, BAG were used for medical application for their ability to form a bond with bone [ ]. Nowadays, the original composition (45S5) and manufacturing method of BAG are modified to create mesoporous BAG, to change particle size (nano or micro-scale) or to add additives [ ]. BAG are considered bioactive materials; however, a better definition of the bioactive effect is required to improve formulations or incorporation of particles in scaffolds [ , ].

It is generally accepted that a bioactive material is a material able to induce specific biological activity and stimulate a beneficial response from the body bonding to the host tissue [ , ]. Regarding BAG, Lebecq et al. defined bioactivity by following the crystalline hydroxy-carbonate apatite (HCA) layer growth on the surface of glass particles [ ]. According to other definitions, the bioactivity is the ability to form mineral deposits in biological conditions [ ].

In the dental field, the definition of bioactivity depends on the clinical use from the ability to induce reprecipitation of HA on the surface of enamel and dentin to cellular effects induced by the release of biologically active substances and ions. There is no consensus on bioactivity’s definition. Vallittu et al. suggested limiting the terms ‘bioactive’ with respect to dental materials only to scientifically proven materials and material combinations that release substantial quantities of ions for specific biomineralization in the clinical environment of the material [ ].

The main objective of this review was to identify and classify the different methodologies used for the BAG bioactivity quantification regarding dental hard tissues, to determine the key parameters considered for these studies and therefore, to influence dental research and clinical practice on an international basis.

Materials and methods

The website COVIDENCE was used to import references and view duplicates, titles, abstracts, and full texts.

Inclusion and exclusion criteria

To identify relevant studies, the following inclusion and exclusion criteria were defined.

The search strategy was conducted to include research articles that have evaluated the bioactivity of BAG (without additives, scaffolds, or other constituents other than SiO 2 , CaO, Na 2 O, or P 2 O 5 ) with the perspective of dental applications. BAG with phosphoric acid (PPA) or polyacrylic acid (PAA) were included because these adjunctions were used to modify the consistency of BAG (from powder to paste) and not the composition.

The search strategy was conducted to exclude case reports, abstracts, literature review articles, retrospective studies, editorials, opinions, surveys, guidelines, conferences and commentary articles, and publications in a language different from English or French.

The series of inclusion and exclusion criteria were established by a consensus of all authors after discussions and while considering the research question—How to evaluate the bioactivity of bioactive glasses for dental applications?—And the objectives of the study.

Search strategy

Four databases were screened: PubMed, Embase, Cochrane Library, and Scopus. The references cited in the articles included were also checked. The published scientific articles from May 1999 to January 2020 were systematically assessed for this review.

Search strategies were developed and performed in the four electronic databases. The search terms were divided in three parts:

  • Teeth, for example, enamel, dentin, dental, dentistry, teeth, and tooth.

  • Bioactive glasses, for example, bioactive glass, bioglass, 45S5, and nanobioactive glass.

  • Bioactivity, for example, remineralization, bioactivity, bioactive, and biomineralization.

Paper selection

The titles and abstracts of all articles identified by the electronic search were read and assessed by two authors (CM and BG) until January 2020. All titles and abstracts were examined and selected in accordance with the eligibility criteria. Those that appeared to fulfil the inclusion criteria, or with insufficient data in the title and the abstract, were selected for full analysis. The two authors were also the two reviewers and assessed the full text articles independently. Any disagreement on the eligibility of studies included was resolved through discussion and consensus.

Data extraction

One author (CM) extracted the data using a prepiloted data collection form, and a second author (BG) verified data extraction independently for completeness and accuracy. Data obtained were as follows: general study details (first author, date of publication); population: BAG investigated ( e.g. glass label, size of particles if mentioned, technique used to elaborate BAG, BAG’s composition, comparison with); and the objectives, criteria, methods (solutions, time of storage, and analysis), and outcomes of studies. Any potential conflict was resolved by a joint discussion between the two authors.

Results

Study selection

The initial electronic search using the keyword combination returned 1077 articles. After the removal of duplicates, 709 records were examined. The title and abstracts of the remaining 709 papers were screened, and 563 papers were excluded because they were irrelevant to the inclusion criteria. Finally, 146 relevant papers were scrutinized by downloading the papers and reading the full text. A consensus between the two authors was reached to determine which studies fully fulfilled the selection criteria. Ninety-eight papers were excluded after reading the full text. Thirteen papers were found from the references of the selected papers, and these were also assessed in a similar manner. Finally, 61 studies were included in this review ( Fig. 1 ).

Fig. 1
Flow diagram of study identification.

Main characteristics of selected articles

A wide range of analysis of bioactivity was presented from the included studies. The most common analysis was the formation of apatite by in vitro evaluation in solutions. Other analysis corresponded to enamel and/or dentin remineralization in vitro , mineralization ability of cells in vitro, and pulp capping or pulpotomy in vivo . Data obtained were as follows: BAG investigated, criteria, methods, and main results.

BAG investigated

The majority of BAG were made by melt-quench (about twenty) and sol–gel techniques (n = 15). There were 4 BAG made by the EISA (Evaporation Induced Self-Assembly) process and 3 by flame spray synthesis.

The size of particles was not systematically specified. About twenty studies stipulated that BAG had a micrometric size, especially 38 or 45 μm. Eight BAG had nanometric size (BGn/nBG/BGNR/NBG), from 10 to 590 nm and included 34, 20–60, 80–90, 100, 510 nm. Some BAG were mesoporous (MBG/MBGs).

The composition of BAG was mainly traditional BAG 45S5 (about thirty). Other studies changed the concentration of SiO, CaO, Na 2 O, or P 2 O 5 to modify the characteristics and bioactivity of BAG. Five BAG were made only with SiO 2 and CaO: 90 or 85 or 70 (%)–10 or 15 or 30 (%), respectively. About twenty BAG were made without Na 2 O.

Comparison with

The BAG without adjuvants were compared with the following:

  • 1: Control group (artificial saliva, demineralized water…).

  • 2: BAG with adjuvants (fluoride (n = 9), potassium (n = 2), strontium (n = 2), magnesium (n = 1), zinc (n = 1), bismuth oxide (n = 1), ampicilline (n = 1), siRNA (Small Interfering Ribonucleic Acid) (n = 1), barium (n = 1)….), or scaffolds (chitosan [CS] or polycarbolactone [PCL]).

  • 3: Oxide alone (ZnO), antiseptic (chlorhexidine [CHX]), desenziting agents (with oxalate) or bioactive products (caseinphosphopeptide-amophouscalciumphosphate [CPP-ACP], stannous fluoride, mineral trioxide aggregate (MTA), formocresol, ferric sulfate, Biodentine™, biosilicate, calcium phosphate cement, calcium hydroxide [CH], BAG modified with soda lime spherical glass or laser irradiation, coating glasses…) or restorative materials: dental adhesive, glass porcelain system, glass ionomer cement/resin-modified glass ionomer cement (GIC/RMGIC).

  • 4: Laser irradiation.

Objectives, Criteria, and Methods – Results in terms of objectives

Mechanism of apatite formation on BAG surface in vitro in solutions

The majority of articles evaluated the bioactivity of BAG in solutions in vitro ( Table 1 ). Simulated body fluid (SBF) (n = 23) was the main solution used; however, a large part of the research used Tris buffer solution (TBS) (n = 7) and one study used Hank’s solution. Two studies used SBF and TBS.

Table 1
Selected articles: In vitro mechanism of apatite formation on BAG surface in solutions. BAG compared with: 1 Control group; 2 BAG with adjuvants; 3 Oxide alone, antibacterial, desensitizing agents, bioactive, or restorative materials. Analysis: 1 Microscopic observations; 2 Chemical or structural analysis. ( _= not specified in the article / m = minutes; h = hours; d = days; w = weeks; m = months ).
References Bag investigated Compared with Criteria Methods Main results
Authors Date Glass label –size Manufacturing methods Glass composition by mol% Interface Contact time Analysis
SiO 2 CaO Na 2 O P 2 O 5 1 2 3 1 2
Takadama – 2001 [ ] Glass specimen MELT-QUENCH 80 0 20 0 Apatite formation SBF 12 h – 1, 5, 10, 17, 28 d X X Na 2 O-SiO 2 glass induced mineralization of apatite on its surface in the SBF.
Forsback – 2004 [ ] S53P4 (<45 <SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m)
Control glass (CG) (<45 <SPAN role=presentation tabIndex=0 id=MathJax-Element-2-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m)
_
_
53
_
20
_
23
_
4
_
X Silica concentration TBS Time up to 24 h X After a short period of immersion, silica is dissolved from both types of glasses, but the amount of silica released is much higher from S53P4 than from CG.
Lin – 2005 [ ] GEL-SILICA Glasses SOL–GEL 70 30 0 0 Apatite formation SBF 20 m – 1, 3, 6, 12, 21.5 h X X After 1 h of SBF soaking, there was a significant increase in the phosphorus density of the phosphorus species on the glass surface. Presumably, an amorphous layer with constituents similar to HA had formed on the glass surface.
Goudouri – 2009 [ ] BG SOL–GEL 60 36 0 4 X Formation of apatite SBF 6, 12, 24, 48 h X X Apatite formation from pure BAG is compared with dental glass ceramic composites products in SBF solutions. Level of bioactivity is evaluated through the kinetic of apatite formation. Porous particles improved the level of bioactivity.
Moawad – 2009 [ ] 48S MELT-QUENCH 48 yCaO – zNa2O: y + z = 49.3 2.7 X Formation of HA layer SBF 7 d X Diffraction peaks for the surface layer on 48S4F (4%CaF 2 ) glass are stronger than those for the layer on 48S glass. This simple comparison suggests that the presence of fluoride ions likely enhanced the bioactivity of BAG.
Brauer – 2010 [ ] GLASS A – 38 <SPAN role=presentation tabIndex=0 id=MathJax-Element-3-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m
MELT-QUENCH 49.47 23.08 26.38 1.07 X Apatite deposition SBF 3 d – 1, 2 w X Incorporation of fluoride that resulted in the formation of FAp compared with fluoride-free glasses.
Gunawidjaja – 2010 [ ] MBG – S85 EISA process 85 10 0 5 Formation of amorphous calcium phosphate layer and crystallization into HCA SBF 30 m – 1, 4 h – 1, 3, 7 d X The phosphorus content increased only marginally over the first 4 h of SBF exposure relative to the initial value of S85. The 2 formations of ACP and HCA partially occurred simultaneously, and the former was most active over the initial 24 h of SBF immersion and the latter dominating between 3 and 7 days.
Mohn – 2010 [ ] 45S5 – 34 nm FLAME SPRAY SYNTHESIS 45 24.5 24.5 6 X Formation of carbonated hydroxyapatite SBF 7 d X X Radiopaque BAG with bismuth oxide had higher in vitro bioactivity regarding the formation of carbonated HA.
Brauer – 2011 [ ] GLASS A MELT-QUENCH 48.47 23.08 26.38 1.07 X Apatite formation TBS 1, 3, 7, 14 d X Glasses formed apatite in TBS. However, Glass A.1 (0.94% CaF 2 ) showed more clearly pronounced peaks and higher peak intensities in XRD compared with fluoride-free glass A.
Goudouri – 2011 [ ] BG SOL–GEL 60 36 0 4 X Apatite formation SBF 6, 12 h – 1, 2, 3, 6, 9 d – 2, 4, 8, 12, 18 d X X The lower rate of bioactivity of the dental ceramic with BG in comparison with the powdered BG samples was a result of the lower surface area of the specimens compared with powdered BG samples.
Mathew – 2011 [ ] MBG EISA process 85 10 0 5 Apatite formation SBF – TBS 16 h X X HA, and the CaP clusters, were present in the pristine MBG pore walls.
Mneimne – 2011 [ ] A – (<38 <SPAN role=presentation tabIndex=0 id=MathJax-Element-4-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m)
A2 – (<38 <SPAN role=presentation tabIndex=0 id=MathJax-Element-5-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m)
MELT-QUENCH 49.47
38.14
23.08
25.91
26.38
29.62
1.07
6.33
Apatite deposition TBS 3, 6, 9 h – 1, 3, 7 d X An increase in phosphate or fluoride content allowed for apatite formation at lower pH.
El-fiqi – 2012 [ ] BGn (80–90 nm) SOL–GEL 85 15 0 0 Apatite formation SBF Different times up to 28 d X X A SBF test of the mesoporous BGn confirmed their excellent apatite-forming ability.
Gunawidjaja – 2012 [ ] S90
S85
S58
EISA process 90
85
58
10
10
37
0
0
0
0
5
5
Formation of HCA SBF 0.5, 4h – 1,3,7 d X The S90 and S85 MBGs displayed similar in vitro behavior, whereas the Ca-richer S58 specimen reacted more similarly to melt-prepared bioactive glasses.
Gunawidjaja – 2012 [ ] S85
S58
_ 85
58
10
37
0
0
5
5
Growth of CaHA – Amounts of amorphous CaP and HA SBF – TBS 1, 4, 8, 16 h – 1, 3, 7 d X X Whereas the TBS grains displayed a 60 μm thick domain of almost pure silica, their SBF counterparts verified small but significant amounts of Ca and P throughout all particles of diameter >20 μm. This finding is attributed to the more extensive local deposits of ACP at the MBG porewalls when they are subjected to SBF, because the latter medium is already supersaturated with respect to apatite.
Mačković – 2012 [ ] 45S5 μBG – (10 μm)
45S5 nBG – (20–60 nm)
MELT-QUENH
FLAME SPRAY SYNTHESIS
44.97
47.8
24.55
25.1
24.55
22.6
5.99
4.6
X Apatite formation SBF 4, 8 h – 1, 3, 7 d X X A higher surface area and, thus, higher reactivity of the nBG particles in comparison to μBG was observed. Investigations revealed a very rapid formation of carbonated nanocrystalline hydroxyapatite after 1 d of immersion in SBF, for nBG.
Salman – 2012 [ ] G1 MELT-QUENCH 48 36 12 4 X Formation of apatite SBF 7, 14, 21 d X X A decrease in the bioactivity of the glass ceramic was observed as Na 2 O was replaced by K 2 O. Sr and Ca ions in the apatite layer formed and were detected with SrO/CaO replacement.
Bachar – 2013 [ ] GN0 EXPERIMENTAL TECHNIQUE (MELTING MIXTURE) 55 13.5 31.5 0 X Apatite layer formation SBF 15 d X X Crystallinity of bioactive apatite layer decreased with increasing nitrogen content, suggesting that nitrogen may slightly decrease bioactivity.
Farooq – 2013 [ ] 45S5 (38–80 μm) MELT-QUENCH 46.1 26.9 24.4 2.6 X Apatite formation TBS 3, 6, 24 h X Glasses formed apatite within 6 h or less, suggesting that they were highly bioactive and capable of forming apatite within a few hours.
Plewinski – 2013 [ ] 45S5 (Amorphous – crystallized samples) MELT-QUENCH 47.3 24.2 22.1 6.2 Apatite formation SBF 1, 7, 14 d X X Calcium silica and calcium carbonate layers were found on amorphous BAG after 7 and 14 d. Apatite formation was observed only on the crystallized 45S5 samples after storage.
Souza – 2013 [ ] 45S5 MELT-QUENCH 46.3 26.9 24.3 2.5 X Formation of an apatite-like layer SBF 4, 8, 16 h – 1, 2, 4, 8, 16 d X X Partial replacement of CaO by MgO in the BAG had no influence on the kinetic of precipitation of the initial ACP layer when glass was exposed to SBF.
Arepalli -2015 [ ] Ba-0 _ 46.1 26.9 24.3 2.6 X Formation of HCA layer SBF 1, 3, 7, 14, 30 d X X The formation of a hydroxyl carbonate apatite layer was observed on the surface of the barium containing BAG after immersion in SBF. However, an increase in barium content in the glass samples decreased the tendency of calcite formation.
Kirsten – 2015 [ ] 45S5 _ 45.53 24.88 23.18 6.29 X Surface reaction layers (HCA) SBF 1, 3.5, 7, 14, 28 d X X 45S5 and BAG with partial substitution of Na 2 O and CaO by K 2 O and MgO exhibited an Si-rich layer of approximately 20 μm and a CaP-rich layer of approximately 10 μm after 14 d of storage in SBF. HCA was found after 3.5–7 d on both glasses.
Abbasi – 2016 [ ] 58S – (<40 μm) SOL–GEL _ _ _ _ X Formation of an apatite layer SBF 6h – 1, 3, 6, 9 d X X The 58S has a high surface area and can release ions very fast in the solution (high bioactivity). Dental ceramic/58S BAG mixtures also exhibit high degrees of bioactivity despite the presence of leucite with non-bioactive behavior.
Wang – 2016 [ ] 45S5 _ _ _ _ _ X Apatite formation SBF 1, 5 d X Crystalline apatites were precipitated on the polycarbolactone (PCL)/submicron BG (smBG) group and 45S5 surfaces after incubation. The thickness of the apatite layer on the PCL/smBG group was higher than for the 45S5 samples.
Mathew – 2017 [ ] S90
S85
S58
EISA process 90
85
58
10
10
37
0
0
0
0
5
5
ACP formation/conversion into HCA – Distinct Ca, Si and P contents SBF 0.25, 1, 4, 8, 24 h – 3, 7, 15, 30 d X HCA formation occurred after 4 h of SBF exposure, except for P-free S90 MBG (after 8 h).
Anand – 2018 [ ] MBG (nano) EXPERIMENTAL TECHNIQUE _ _ 0 _ Carbonated HA forming ability SBF 24, 48 h X X Formation of hydroxyapatite layer on different surfactants was evaluated: non-ionic surfactant pluronic and ionic surfactant hexadecyltrimethyl-ammonium bromide in contrast with non-ionic surfactant polyethylene glycol and citric acid.
Ashok – 2018 [ ] BGNR – 45S5 SOL–GEL 45 24.5 24.5 6 X Formation of hydroxyl carbonated apatite layer (HCA) Hank’s solution 3, 7 d X X On the 3 rd day, the formation of the HCA layer is relatively higher in nano hybrids of BGNR/rGO (reduced graphene oxide sheets) compared with that of BGNR. Similar levels of HCA formation in BGNR were observed only on the 7th day.
Taha – 2018 [ ] 45S5 (Sylc TM ) air-abrasion MELT-QUENCH 46.1 26.9 24.4 2.6 X Apatite formation TBS 1, 3, 6, 9, 24 h X BAG with CaF 2 formed apatite faster (6 h) than 45S5 (Sylc TM ) (24 h) in TBS.

The objectives and criteria of these studies were to evaluate the formation of apatite in vitro . There was no consensus on contact time: 15, 20, or 30 min; 1, 3, 4, 6, 8, 9, or 12 h; 1, 2, 3, 5, 7, 9, 17, or 30 days; and 2, 3 or 4 weeks. Studies used the following analysis techniques:

  • Microscopic observations: Scanning electron microscopy (SEM), field emission-SEM (FESEM), and transmission electron microscopy (TEM).

  • Chemical or structural analysis: Energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), solid state nuclear magnetic resonance (NMR), Raman spectroscopy, inductively coupled plasma (ICP), and UV–vis spectrophotometer.

  • Association between microscopy and chemical or structural analysis : SEM-EDX.

The main analysis techniques were SEM, FTIR, XRD, and solid state NMR ( Fig. 2 ).

Fig. 2
Number of publications reported for each analysis technique of apatite formation in vitro in solutions.

Results lead to the following conclusion: apatite formation occurs by contact with BAG and solutions.

BAG capacity to remineralize enamel and/or dentin in vitro

To evaluate the ability of BAG to remineralize dental tissues, 16 studies used human dentin, 9 studies used human enamel, and 2 studies bovine enamel in vitro ( Table 2 ).

Table 2
Selected articles: in vitro BAG remineralization of enamel and/or dentin. BAG compared with: 1 Control group; 2 BAG with adjuvants; 3 Oxide alone, antibacterial, desensitizing agents, bioactive, or restorative materials; 4 Laser. Analysis: 1 Microscopic observations; 2 Chemical or structural analysis; 3 Mechanical properties evaluation. (_= not specified in the article / s = seconds; m = minutes; h = hours; d = days; w = weeks; m = month s).
References Bag investigated Compared with Criteria Methods Main results
Authors Date Glass label –size Manufacturing methods Glass composition by mol%1 Interface Contact time Analysis
SiO 2 CaO Na 2 O P 2 O 5 1 2 3 4 1 2 3
Efflandt – 2002 [ ] 45S5 MELT-QUENCH 45 24.5 24.5 6 X Apatite formation Human dentin 5, 21, 42 d X X Ions from glass penetrated dentin. Presence of apatite at the interface between glass and dentin was observed.
Forsback – 2004 [ ] S53P4 (<45 <SPAN role=presentation tabIndex=0 id=MathJax-Element-6-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m)
Control glass (CG) (<45 <SPAN role=presentation tabIndex=0 id=MathJax-Element-7-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>μμ
μ
m)
_
_
53
_
20
_
23
_
4
_
X Occlude dentin tubules – Formation of CaP Human Dentin 14 d X X Pretreatment with BAG decreased the degree of decalcification of dentin during the mineralization process.
Hassanein – 2006 [ ] S53P4 _ 53 20 23 4 X Topography of the remineralized areas – Nature of the compounds deposited – Degree of remineralization Human enamel and dentin 10 d X X BAG has the potential to remineralize artificial carious lesions in enamel and dentin: formation of hydroxyapatite, sealing of enamel pores, and plugging of dentinal tubules.
Lee – 2007 [ ] DP-BAG with 30% PPA SOL–GEL
MELT-QUENCH
39.6 40 8.4 12 Dentinal tubule occlusion Human dentin 3 d X X Percentage of tubular occlusion with DP-BAG was 53.2%–65.4% and significantly better than Seal & Protect (41.2%).
Schmidlin – 2007 [ ] S53P4 (≤ 45 <SPAN role=presentation tabIndex=0 id=MathJax-Element-8-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>𝜇μ
μ
m)
_ _ _ _ _ X X Improve mechanical properties – Higher hardness Human Dentin 3 w X Hardness and elastic modulus values of the dentin subjacent to empty microcavities and counterparts lined were significantly higher with BAG compared with the RMGIC.
Vollenweider – 2007 [ ] 45S5 NBG – 45S5 BG (PerioGlas® 90−710 <SPAN role=presentation tabIndex=0 id=MathJax-Element-9-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>𝜇μ
μ
m)
FLAME SPRAY SYNTHESIS (NBG) 44.7 27.6 22.8 4.9 X New mineral precipitated – Improve mechanical properties Human dentin 1, 10, 30 d X X X After treatment with nano-BAG for 10 or 30 d, a pronounced increase in mineral content of the dentin was observed. A substantially higher remineralization rate was induced by nanometer-sized vs . micrometric.
Curtis – 2010 [ ] 70S30C (0.65 <SPAN role=presentation tabIndex=0 id=MathJax-Element-10-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>𝜇μ
μ
m)
45S5 (3.30 <SPAN role=presentation tabIndex=0 id=MathJax-Element-11-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>𝜇μ
μ
m)
SOL–GEL
MELT-QUENCH
70
45
30
24.5
0
24.5
0
6
Tubule occlusion – Formation of an apatite layer Human dentin 24 h X X Treatment with nanobioglass resulted in particle deposition within tubules and formation of apatite rods.
Bakry – 2011 [ ] 45S5 with 50% PAA _ 45 24.4 24.5 6 X Tubule orifice Closure – Recover mechanical properties Human dentin 24 h X X X 45S5 could occlude the dentinal tubule orifices with calcium phosphate crystals.
Dong – 2011 [ ] 45S5
58S
77S
MELT-QUENCH
SOL–GEL
SOL–GEL
44.8
62.8
73.7
26.5
27.6
16.5
23.4
0
0
5.3
9.6
9.8
X Mineralized layer – Surface roughness – Nano-hardness and Nano-reduced elastic modulus Human enamel 7 d X X X Enamel surface formed a homogenous, dense mineralized layer with the treatment of 45S and 58 s samples. 77S treatment showed a loose and uneven remineralized layer. These results also indicated that the level of silicon content of BAG played a key role in dental enamel remineralization.
Sauro- 2011 [ ] 45S5 (Sylc TM ) _ _ _ _ _ X Dentin permeability – Hydroxyapatite precipitation Human dentin 24, 48 h X X 45S5 (Sylc TM ) was the only substance (compared with prophylactic materials) able to reduce dentin permeability after immersion in remineralising solution and to show hydroxyapatite precipitation.
Wang – 2011 [ ] BAG (30−90 <SPAN role=presentation tabIndex=0 id=MathJax-Element-12-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>𝜇μ
μ
m)
_ 45 24.5 24.6 5.8 X Mineral variation of the surface – Apatite formation – Roughness of the surface Human dentin 7 d X X Results showed a significant increase of the mineral matrix area ratio in dentin specimens treated with BAG and M-BAG (with magnesium). Both formulations have similar potential in dentine remineralization.
Bakry – 2013 [ ] 45S5 with 50% PPA _ 45 24.4 24.5 6 X X Dentin permeability – Examination of surfaces (chemical nature – crystalline structures) Human dentin 24 h X X X Application of 45S5 BAG paste to dentin occluded patent dentinal tubule orifices with a layer of calcium phosphate crystals.
Gjorgiesvska – 2013 [ ] 45S5 _ _ _ _ _ X Observe ion exchange layer – Determine the elemental levels (%) of ions Human dentin 6 w X X GIC and BAG underwent ion exchange with the surrounding tooth tissue, confirming their bioactivity. The particle size of BAG meant that cavity adaptation was poor. Smaller particle size BAG may provide a more acceptable result (<90 <SPAN role=presentation tabIndex=0 id=MathJax-Element-13-Frame class=MathJax style="POSITION: relative" data-mathml='μ’>𝜇μ
μ
m).
Bakry – 2014 [ ] 45S5 with 50% PPA _ 45 24.4 24.5 6 X X Improve mechanical properties of demineralized subsurfaces Human enamel 24 h X X X 45S5 paste application improved the microhardness of the subsurface eroded enamel compared with the fluoride and control specimens.
Bakry – 2014 [ ] 45S5 with 50% PPA _ 45 24.4 24.5 6 X Layer of hydroxyapatite crystals Human enamel 24 h X X Artificial enamel caries lesions treated with BAG paste showed complete coverage with a layer of brushite crystals.
Milly – 2014 [ ] BAG 45S5 slurry (2–6 – 12 μm) – PAA-BAG (40 wt%-60 wt%) _ 45 24.4 24.6 6 X X Mechanical properties – Phosphate content – Morphological changes Human enamel 7 d X X X BAG and PAA-BAG surface treatments enhanced enamel remineralization: improved mechanical properties, higher phosphate content, and morphological changes within the artificial lesions.
Milly – 2015 [ ] BAG 45S5 slurry (2–6 – 12 μm) _ _ _ _ _ X X Average roughness – Optical changes – Structural changes of WSL Human enamel Twice daily (5 min per application) for 21 d X X X The pretreatment enhanced the remineralization of WSL treated with BAG 45S5 slurry: increased mineral content, improved mechanical properties and ultrastructural changes.
Carvalho – 2016 [ ] Bio-Gran + distilled water EXPERIMENTAL TECHNIQUE (MELTING MIXTURE) 42.3 28.3 22.8 6.6 X X Release of Ca, Na and P ions Human dentin 10 min – 24 h – 7, 14, 21, 30 d X CH had the highest level of Ca ions release at 30 d. The BAG released more Na and P ions and presented an alkaline pH immediately and after 30 d.
El-wassefy – 2017 [ ] 45S5 with 50% PPA _ 45 24.4 24.5 6 X X X Changes in the mineral content – High microhardness Bovine enamel 24 h X X X Treating demineralized enamel with cold plasmas before BAG application ensued a significant high mineral volume recovery and microhardness of demineralized region.
Saffarpour – 2017 [ ] BG (40–90 μm) _ 64 26 0 10 X Chemical structure – Presence of globular HA crystals – Tubular obstruction Human dentin 7, 14, 21 d X X Dentinal tubules were partially occluded by BG and BG modified with 5% Strontium, and they almost completely obstructed after the use of BG modified with 10% Sr. Addition of 10% Sr to BG enhanced apatite formation. Addition of 5% Sr to BG stabilized the apatite lattice and increased the remineralization.
Taha – 2018 [ ] 45S5 (Sylc TM ) air- abrasion _ _ _ _ _ X Intensity of light backscattering – Roughness – Hardness – Mineral precipitate-like deposits – Presence of Ca, P, O and Na Human enamel 24 h X X X BAG with CaF 2 enhanced enamel remineralization more effectively than 45S5. Surface roughness and intensity of light backscattering similar to that of sound enamel were observed following treatment with fluoride-containing BAG.
Zhang – 2018 [ ] BG (Novamin®) – BG (Novamin®)+PAA _ _ _ _ _ X X X Change of surface mineral content – Improve mechanical properties – Identify the type of newly formed minerals – Surface morphologies and Ca/P ratio Human enamel 7 d X X X BG+PAA presented significantly higher mineral regain compared with negative control on lesions surfaces. Chitosan (CS) improved the remineralization efficacy using either a BG slurry alone or BG+PAA complexes as both surface and subsurface showed an increased tendency in mineral content assessed and greatest hardness recovery.
Zhang – 2018 [ ] BG (Novamin®) – BG (Novamin®)+PAA _ _ _ _ _ X X X Mineral content/changes – Sub/surface microhardness – Formation of pellicle layer Human Enamel 7 d X X X Chitosan-BG exhibited denser subsurface structure than BG, and in CS-BG + PAA, the crystals were bigger in size but were more enamel-like compared with BG + PAA, as shown in SEM observations.
Lee – 2019 [ ] BG + PPA SOL–GEL 58 33 0 9 X X Tubules obstructions – Formation of HA – Chemical changes in collagen fibers Human dentin 5 min X X BG with PPA prevented the formation of cracks and degradation of collagen fibers caused by CO 2 irradiation and promoted obliteration of the exposed dentinal tubules.
Dionysopoulos – 2019 [ ] BAG (Novamin®) 45S5 (30−60-90 μm) _ 45 24.4 24.6 6 X X Enamel surface loss – Mechanical properties Bovine enamel 10 s X X X Surface pretreatment with BAG 45S5 reduced surface loss after erosion/abrasion challenge compared with the negative control group.
Ubaldini –2020 [ ] 45S5 (BG) _ 45 24.5 24.5 6 X Chemical composition and bond strength of dentin Human dentin 30 s X X X BG and biosilicate promoted mineral matrix ratios increase in the control dentin and bleached dentin. Both bioactive materials presented a high remineralization ability on bleached dentin surfaces (improved dentin’s ability to chemically interact with adhesive monomers and consequently increased the resin-dentin bond strength).
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Aug 18, 2020 | Posted by in Dental Materials | Comments Off on Bioactivity assessment of bioactive glasses for dental applications: A critical review
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