Correction to: Biodentine™ material characteristics and clinical applications: a 3 year literature review and update.

Owing to a misunderstanding on the part of the authors, the name of the last author, Prof. R. M. H. Verbeeck, was omitted from this article.

Addition of bioactive glass to glass ionomer cements: Effect on the physico-chemical properties and biocompatibility.

OBJECTIVES: Glass ionomer cements (GICs) are a subject of research because of their inferior mechanical properties, despite their advantages such as fluoride release and direct bonding to bone and teeth. Recent research aims to improve the bioactivity of the GICs and thereby improve mechanical properties on the long term. In this study, two types of bioactive glasses (BAG) (45S5F and CF9) are combined with GICs to evaluate the physico-chemical properties and biocompatibility of the BAG-GIC combinations. The effect of the addition of Al3+ to the BAG composition and the use of smaller BAG particles on the BAG-GIC properties was also investigated. MATERIALS AND METHODS: Conventional aluminosilicate glass (ASG) and (modified) BAG were synthesized by the melt method. BAG-GIC were investigated on setting time, compressive strength and bioactivity. Surface changes were evaluated by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), EDS and PO43- -and Ca2+ uptake in SBF. Biocompatibility of selected BAG-GICs was determined by a direct toxicity assay. RESULTS: The addition of BAG improves the bioactivity of the GIC, which can be observed by the formation of an apatite (Ap) layer, especially in CF9-containing GICs. More BAG leads to more bioactivity but decreases strength. The addition of Al3+ to the BAG composition improves strength, but decreases bioactivity. BAGs with smaller particle sizes have no effect on bioactivity and decrease strength. The formation of an Ap layer seems beneficial to the biocompatibility of the BAG-GICs. SIGNIFICANCE: Bioactive GICs may have several advantages over conventional GICs, such as remineralization of demineralized tissue, adhesion and proliferation of bone- and dental cells, allowing integration in surrounding tissue. CF9 BAG-GIC combinations containing maximum 10mol% Al3+ are most promising, when added in ≤20wt% to a GIC.

Bioactivity and biocompatibility of two fluoride containing bioactive glasses for dental applications.

OBJECTIVE: Bioactive glasses (BAG) form, in contrast to formerly used implant materials, a stable bond with tissues, especially bone, when implanted. Nowadays BAGs are often mixed with a cement/composite that hardens in situ to broaden its applications in dentistry or orthopedics. The bioactivity and biocompatibility of possible BAG candidates for BAG-cement/composite development were evaluated. METHODS: Two fluoride containing BAGs were tested: a Na+-containing (45S5F), based on the first commercial BAG, and a Na+-free BAG (CF9), with a higher Ca2+ and PO43- content. BAGs were tested on their bioactivity upon immersion in SBF for 7days by evaluating the surface changes by FT-IR, SEM, EDS and PO43- and Ca2+ uptake and/or release from SBF. Moreover, the biocompatibility of the BAGs was investigated with a direct contact cell viability study with HFF cells and a cell adhesion study with MG-63 cells. RESULTS: The Na+-free BAG, CF9, showed the highest potential to bioactivate cements because of its high Ca2+-release and apatite (Ap) formation, as evidenced by SEM pictures and corresponding EDX patterns. FT-IR confirmed the formation of an Ap layer. Moreover CF9 had a higher biocompatibility than 45S5F. SIGNIFICANCE: For the bioactivation of GICs/composites in order to enhance bonding and remineralization of surrounding tissues, fluoride containing BAG may have advantages over other BAGs as a more stable fluorapatite can be formed. CF9 may be an excellent candidate therefore.

The influence of particle size and fluorine content of aluminosilicate glass on the glass ionomer cement properties.

OBJECTIVE: Glass ionomer cements (GIC) are clinically accepted dental restorative materials mainly due to their direct chemical adhesion to both enamel and dentin and their ability to release fluoride. However, their mechanical properties are inferior compared to those of amalgam and composite. The aim of this study is to investigate if combinations of nano- and macrogranular glass with different compositions in a glass ionomer cement can improve the mechanical and physical properties. METHODS: Glasses with the composition 4.5 SiO2-3 Al2O3-1.5 P2O5-(5-x) CaO-x CaF2 (x=0 and x=2) were prepared. Of each type of glass, particles with a median size of about 0.73 µm and 6.02 µm were made. RESULTS: The results show that the setting time of GIC decreases when macrogranular glass particles are replaced by nanogranular glass particles, whereas the compressive strength and Young's modulus, measured after 24 h setting, increase. The effects are more pronounced when the nanogranular glass particles contain fluoride. After thermocycling, compressive strength decreases for nearly all formulations, the effect being most pronounced for cements containing nanogranular glass particles. Hence, the strength of the GIC seems mainly determined by the macrogranular glass particles. Cumulative F--release decreases when the macrogranular glass particles with fluoride are replaced by nanogranular glass particles with(out) fluoride. SIGNIFICANCE: The present study thus shows that replacing macro- by nanogranular glass particles with different compositions can lead to cements with approximately the same physical properties (e.g. setting time, consistency), but with different physicochemical (e.g. F--release, water-uptake) and initial mechanical properties. On the long term, the mechanical properties are mainly determined by the macrogranular glass particles.

Biodentine™ material characteristics and clinical applications: a review of the literature.

INTRODUCTION: Biodentine™ is a new version of calcium silicate-based inorganic cement. AIM: The aim of this review is to provide a detailed analysis of the physical and biological properties of Biodentine™ and to compare these properties with those of other tricalcium silicate cements viz. mineral trioxide aggregate (MTA) and Bioaggregate™ (Bioaggregate). STUDY DESIGN: A comprehensive systematic literature search for all publications to date was performed on 20th November 2013 by two independent reviewers in Medline (PubMed), Embase, Web of Science, CENTRAL (Cochrane), SIGLE, SciELO, Scopus, Lilacs and clinicaltrials.gov using the search terms Biodentine, "tricalcium silicate", Ca3SiO5, "dentine substitute", "dentin substitute" and RD 94. In addition to the electronic search, hand searches and reference searches were performed to include articles published in journals that were not indexed in Medline. Randomised control trials (RCT), case control studies, case series, case reports, in vitro studies, animal studies and short communications in English language were considered for this review. CONCLUSIONS: Considering the superior physical and biologic properties, Biodentine™ could be an efficient alternative to MTA to be used in a variety of clinical applications. There appears to be a wide range of clinical applications where Biodentine™ could be used in the field of endodontics, dental traumatology, restorative dentistry and pediatric dentistry. Although it seems to be good clinical practice, currently there is little clinical evidence to support all potential indications.

Fracture resistance of bone samples filled with fibre-reinforced composite posts: an ex vivo model.

AIM: To evaluate the strengthening effect of two different types of fibre-reinforced composite (FRC) posts in an ex vivo experimental model. METHODOLOGY: Compact and hollow bone samples from bovine femurs were used as standardized samples. A total of 80 hollow samples were divided into two groups and filled either with a prefabricated FRC post or with individually adapted FRC posts. For each group, half of the samples were subjected to thermocycling (5-55 °C, 5000×). The remaining samples were kept for 24 h at 37 °C at 100% relative humidity. All samples were loaded diametrically until fracture. The null hypothesis tested was that the fracture resistance of standardized bone samples is not influenced by the type of FRC post, independently of the exposure to thermocycling. Results were evaluated by anova, and subsequent multiple comparisons were performed. RESULTS: The samples filled with the individually adapted FRC posts were more resistant to fracture than the prefabricated ones (P < 0.001), but this difference was not apparent in the thermocycled groups. Detachment of the posts upon fracture was highest after thermocycling for both groups, amounting to 55% and 95% for the individual adapted posts and the prefabricated posts, respectively. CONCLUSIONS: Initially, the samples filled with the individually adapted FRC posts were more resistant to fracture than those filled with the prefabricated ones. However, after ageing of the samples, both types of posts had similar strengthening effects.

Pulpal regeneration and root development after subcutaneous transplantation of cryopreserved immature teeth in rats.

The purpose of this in vivo study was to investigate revascularization and root growth after autotransplantation of cryopreserved immature teeth. Immature molar teeth were extracted in 4-week-old Wistar rats. In the test group, teeth were cryopreserved for 1 week and transplanted subcutaneously to the abdomen. In the control group, teeth were transplanted subcutaneously immediately after extraction. Material was collected in test and control animals at intervals of 1, 2, 4 and 10 weeks post-transplantation and histological and microradiographical examination was performed. Results showed that during the first weeks after transplantation, pulpal repair was similar in both groups although degenerated pulpal tissue was replaced slower in cryopreserved teeth and some differences in types of hard tissue formation were found between test and control teeth. After 10 weeks, the differences in the regenerated pulpal tissue between cryopreserved and control teeth observed during the first weeks were no longer detectable. No root growth was detected microradiographically 10 weeks after transplantation in any of the transplanted teeth. The presence of dentin-like tissue in the pulp cavity of some autotransplanted cryopreserved teeth, suggests survival of pulpal tissue after cryopreservation.

Review: finishing and polishing procedures of (resin-modified) glass ionomers and compomers in paediatric dentistry.

BACKGROUND: A smooth surface has a beneficial effect on the aesthetic quality and longevity of a dental restoration, as well as on its biocompatibility with oral tissues. In this review studies on glass-ionomer cements (GIC), resin-modified glass-ionomer cements (RM-GIC), and compomers or polyacid-modified resin composites (PAM-C) were assessed as these are currently used in paediatric dentistry. METHOD: Medline databases (USA National Library of Medicine) was searched using WinSpirs and Pubmed. This search used a keyword filter including dental materials, polishing procedures, and instrumentation including influencing factors. FINDINGS: Although the literature shows different commercially available tools it seems that the ideal polishing instrumentation in paediatric dentistry for GIC and compomers is not yet on the market. Furthermore, the constant development of dental materials and polishing products impose a need for continuous scientific research.

Seckel syndrome associated with oligodontia, microdontia, enamel hypoplasia, delayed eruption, and dentin dysmineralization: a new variant?

Seckel syndrome (SCKL) [OMIM Entry 210600] is a rare, autosomal recessive syndrome, characterized by severe intrauterine and postnatal growth retardation, microcephaly, mental retardation, and typical facial appearance with beaklike protrusion of the midface (bird-headed). Associated findings may include limb anomalies, dislocation of femoral heads, scoliosis, and gastrointestinal malformation. A 14-year-old boy is presented with brain hypoplasia, pachygyria, hydrocephaly, enamel hypoplasia and root dysplasia in the temporary dentition, and oligodontia, severe microdontia, and delayed eruption of the permanent dentition. The association of SCKL with the above unusual dental findings may represent a new phenotype.

Infrared spectrometric study of acid-degradable glasses.

The composition of glasses used in glass-ionomer cements affects their leaching behavior and hence the properties of the cement. The aim of this study was to correlate the composition and leaching behavior of these glasses with their infrared absorption characteristics. The wavenumber of the absorption band of the Si-O asymmetric stretching vibration shifts to a higher value with decreasing content of mono- and bivalent cations in the glass. This effect can be ascribed to the influence of these extraneous ions on the glass network order and connectivity. Preferential leaching of these ions induces an increase of asymmetric stretching vibration and a general modification of the band profile. The results can be correlated with the x-ray diffraction characteristics of the glass.

X-ray diffraction study of acid-degradable glasses.

The composition of the degradable glasses used in commercial dental glass-ionomer cements determines their leaching behavior and hence the properties of the cement. The objective of the present study was to assess if the composition and leaching in acetic acid solutions are reflected in the x-ray diffraction characteristics of these glasses. The position (2theta) of the maximum of the first sharp diffraction peak shifts to higher diffraction angles with increasing number and ionic radius of mono- and bivalent cations in the glass. Upon acid-leaching, these ions are preferentially leached out, so that (2theta) decreases. These results can be related to the decreasing Si-Si distance in the glass network with increasing modifier radius.

X-ray diffractometric determination of crystalline phase content in bioactive glasses.

A rapid routine determination of the content of crystalline CaF(2) and Al(2)O(3) inclusions in bioactive glass ceramics is performed using X-ray diffractometry with a standard addition technique. Multiple ratio analysis, even using peaks with different broadenings, indicates that differences in crystallite properties (e.g., crystal imperfection, particle size and morphology, preferred orientation) between the unknown sample and standard do not bias the result. In this respect, an exact match between their crystallographic integrities does not seem to be required for a reliable estimation of the crystalline content with a relative standard deviation of 7%.

Fluoride release from glass ionomer activated with fluoride solutions.

The mechanism of the fluoride release from glass-ionomer cements (GICs) is not yet completely understood, due to the complexity of these systems. The objective of the present study was to investigate the fluoride and alkali metal ion release from a relatively simple GIC formulation with fluoride- and alkali metal-free glass and activated with a NaF or KF solution. The set formulations were eluted during 168 days in water at 37 degrees C. The cumulative fluoride release was the result of an initial high release that ceased after some time and a prolonged but slow release, both of which increased with increasing fluoride concentrations in the activating solution, independently of the type of alkali metal. Maturation prior to elution decreased the fluoride and slowed the alkali metal release. The release of these ions was not (completely) correlated. The results suggest that the release process is due not only to a loss of relatively loosely bound fluoride in the cement matrix, but also to the release of fluoride which becomes strongly bound during the setting reaction and induces a long-term release.

Fluoride release of polyacid-modified composite resins with and without bonding agents.

OBJECTIVES: The aim of this study was to investigate the influence of the proprietary bonding agents Hytac OSB (OSB) (Espe), Prime&Bond 2.1 (PB) (Dentsply DeTrey) and Syntac Single Component (SSC) (Vivadent) on the fluoride release of the corresponding polyacid-modified composite resins Hytac (HTC), Dyract AP (DAP) and Compoglass F (CGF), respectively. METHODS: Ten cylindrical specimens (6mm diameter and 3mm thick) of each polyacid-modified composite were prepared according to the manufacturers' instructions: five with bonding agent applied and five without bonding agent as a control. The specimens were immersed individually in 10ml ultra-pure water at 37 degrees C immediately after light-curing of the polyacid-modified composite resins. Over 140 days, the water was regularly renewed and the fluoride concentration eluted during each period was determined with a combined fluoride ion selective electrode. RESULTS: The fluoride release decreases according to the sequence: CGF>DAP>HTC. The bonding agent significantly reduces the fluoride released by DAP and CGF, respectively, by a factor 2-3 and +/-1.4. For HTC, the bonding agent reduces the fluoride released initially by a factor of +/-2, but the difference between the fluoride release with and without bonding agent becomes insignificant after approximately 3 weeks. SIGNIFICANCE: It can be concluded that the use of bonding agent can significantly reduce fluoride release of polyacid-modified composite resins in the long-term, and especially in the short-term. The decrease in fluoride release might reduce the material's potential to prevent recurrent caries.

Effect of a neutral citrate solution on the fluoride release of resin-modified glass ionomer and polyacid-modified composite resin cements.

The effect of 0.01 mol/l citrate solution at pH = 7 on the fluoride release is compared for the resin-modified glass ionomer cements (RM-GIC) GC Lining LC, PhotacBond, Vitremer and Vitrebond and for the polyacid-modified composite resins (PAM-C) Variglass and Dyract by means of the six-month fluoride release profiles at 37 degrees C. The fluoride release of both RM-GIC and PAM-C increases in the neutral citrate solution as compared to water, which can be explained by the ability of citrate to complex metal ions and hence to degrade the glass as well as the polysalt matrix of the cement. Although RM-GIC release more fluoride than PAM-C in water as well as in citrate solution, the relative increase in fluoride release upon immersion in citrate solution is most pronounced for PAM-C. Whereas for the latter citrate affects both the short-term and long-term fluoride release, for RM-GIC only the long-term fluoride release is affected. This suggests that the action of citrate increases with decreasing importance of the polysalt formation in the hardening of the material. This could be explained on the basis of the difference in the chemical properties of the cement matrix.

Conversion of octacalcium phosphate in calcium phosphate cements.

This study investigated the in vitro conversion reaction in calcium phosphate cements (CPCs) containing octacalcium phosphate (OCP) as one of the reagents. OCP is known to be a precursor for apatite formation in vivo. The reaction products were characterized using infrared spectroscopy and X-ray diffraction. Although the conversion of OCP into hydroxyapatite is thermodynamically favorable, OCP only yields apatite formation in CPC provided it is combined with a highly soluble Ca(2+) and OH(-) releasing reaction partner. In this respect, tetracalcium phosphate is a promising compound. Adding small amounts of monocalcium phosphate monohydrate can stimulate the setting through intermediate brushite formation. The preparation method of OCP might drastically affect the performance of the cement. The reaction path of the setting of these CPC probably does not conform to the singular point principle described in the literature, and an in situ hydrolysis of OCP to apatite is conceivable. Simulation of apatite formation using OCP as the precursor and/or seed in CPC might be beneficial for some biomedical applications.

Effect of maturation on the fluoride release of resin-modified glass ionomer and polyacid-modified composite resin cements.

The effect of an early water contact on the fluoride release is studied for the resin-modified glass ionomer cements (RM-GIC) GC Lining LC, PhotacBond, Vitremer and Vitrebond and for the polyacid-modified composite resins (PAM-C) Variglass and Dyract. Six months fluoride release profiles were determined in regularly renewed water (37 degrees C), for the products directly after light curing and after 24 h maturation in a humid atmosphere (85% RH). ANOVA shows that both the short-term and the long-term fluoride release of a RM-GIC are influenced by this maturation. This indicates that direct water contact for this material should be avoided. For the RM-GIC a correlation is found between the initial fluoride release process and the long-term process. For the PAM-C materials, no differences in the fluoride release are found as a function of maturation, indicating that early water contact has no effect. The amounts of fluoride released by PAM-C are low compared to RM-GIC, which can affect their caries preventive potential. The results are explained on the basis of the setting reaction of both types of materials.

Fluoride release profiles of mature restorative glass ionomer cements after fluoride application.

This study investigates the fluoridation of four conventional glass ionomer cements (GIC) (ChemFil Superior encapsulated, Fuji Cap II, Ketac-Fil and Hi Dense) and three resin-modified GIC (RM-GIC) (Fuji II LC encapsulated, Photac-Fil and Vitremer). The fluoride release of matured restorative GIC was measured as a function of time, after four repeated fluoridations in a 2% NaF aqueous solution for 1 h. This release was corrected for the intrinsic release as determined with a control group. It was demonstrated that application of fluoride is capable of recharging GIC but the subsequent high fluoride release only lasts for one or a few days. Moreover, the fluoride release behaviour depends on the cement formulation. Comparable to the intrinsic release, the net fluoride release after fluoridation is composed of a short- and a long-term process, the former being predominant after fluoridation. The total amount of fluoride released according to the short-term process increases with consecutive fluoridations. This is especially pronounced for the RM-GIC, who exhibit a relatively slow release after fluoridation as compared to the conventional GIC. An explanation for these results is suggested on the basis of the physicochemistry of the setting reaction of the cements and of the fluoridation process.

Effect of temperature and immersion on the setting of some calcium phosphate cements.

Calcium phosphate cements based on powders containing alpha-Ca3(PO4)2 and aqueous solutions containing Na2HPO4 as accelerator were used to determine the effects of accelerator concentration, temperature and immersion on the setting time. Increases in accelerator concentration and temperature increased the rate of setting, but immersion had a retarding effect. These results were used to design a method whereby a syringe filled with cement paste can be kept ready for injection of the paste into the implantation site for a long time, whereas setting of the cement paste in the body takes place in a short time.