Incorporation of Casein Phosphopeptide-Amorphous Calcium Phosphate into a Glass-ionomer Cement

Layer-by-layer self-assembly of PLL/CPP-ACP multilayer on SLA titanium surface: Enhancing osseointegration and antibacterial activity in vitro and in vivo

Dental Implants are expected to possess both excellent osteointegration and antibacterial activity because poor osseointegration and infection are two major causes of titanium implant failure. In this study, we constructed layer-by-layer self-assembly films consisting of anionic casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) and cationic poly (L-lysine) (PLL) on sandblasted and acid etched (SLA) titanium surfaces and evaluated their osseointegration and antibacterial performance in vitro and in vivo. The surface properties were examined, including microstructure, elemental composition, wettability, and Ca2+ ion release. The impact the surfaces had on the adhesion, proliferation and differentiation abilities of MC3T3-E1 cells were investigated, as well as the material's antibacterial performance after exposure to the oral microorganisms such as Porphyromonas gingivalis (P. g) and Actinobacillus actinomycetemcomitans (A. a). For the in vivo studies, SLA and Ti (PLL/CA-3.0)10 implants were inserted into the extraction socket immediately after extracting the rabbit mandibular anterior teeth with or without exposure to mixed bacteria solution (P. g & A. a). Three rabbits in each group were sacrificed to collect samples at 2, 4, and 6 weeks of post-implantation, respectively. Radiographic and histomorphometry examinations were performed to evaluate the implant osseointegration. The modified titanium surfaces were successfully prepared and appeared as a compact nano-structure with high hydrophilicity. In particular, the Ti (PLL/CA-3.0)10 surface was able to continuously release Ca2+ ions. From the in vitro and in vivo studies, the modified titanium surfaces expressed enhanced osteogenic and antibacterial properties. Hence, the PLL/CPP-ACP multilayer coating on titanium surfaces was constructed via a layer-by-layer self-assembly technology, possibly improving the biofunctionalization of Ti-based dental implants.

Evaluating Glass Ionomer Cement Longevity in the Primary and Permanent Teeth-An Umbrella Review

The aim of this umbrella review was to evaluate the longevity of glass ionomer cement (GIC) as a restorative material for primary and permanent teeth. Research in the literature was conducted in three databases (MedLine/PubMed, Web of Science, and Scopus). The inclusion criteria were: (1) to be a systematic review of clinical trials that (2) evaluated the clinical longevity of GICs as a restorative material in primary and/or permanent teeth; the exclusion criteria were: (1) not being a systematic review of clinical trials; (2) not evaluating longevity/clinical performance of GICs as a restorative material; and (3) studies of dental restorative materials in teeth with enamel alterations, root caries, and non-carious cervical lesions. Twenty-four eligible articles were identified, and 13 were included. The follow-up periods ranged from 6 months to 6 years. Different types of GICs were evaluated in the included studies: resin-modified glass ionomer cement (RMGIC), compomers, and low- and high-viscosity glass ionomer cement. Some studies compared amalgam and composite resins to GICs regarding longevity/clinical performance. Analyzing the AMSTAR-2 results, none of the articles had positive criteria in all the evaluated requisites, and none of the articles had an a priori design. The criteria considered for the analysis of the risk of bias of the included studies were evaluated through the ROBIS tool, and the results of this analysis showed that seven studies had a low risk of bias; three studies had positive results in all criteria except for one criterion of unclear risk; and two studies showed a high risk of bias. GRADE tool was used to determine the quality of evidence; for the degree of recommendations, all studies were classified as Class II, meaning there was still conflicting evidence on the clinical performance/longevity of GICs and their recommendations compared to other materials. The level of evidence was classified as Level B, meaning that the data were obtained from less robust meta-analyses and single randomized clinical trials. To the best of our knowledge, this is the first umbrella review approaching GIC in permanent teeth. GICs are a good choice in both dentitions, but primary dentition presents more evidence, especially regarding the atraumatic restorative treatment (ART) technique. Within the limitation of this study, it is still questionable if GIC is a good restorative material in the medium/long term for permanent and primary dentition. Many of the included studies presented a high risk of bias and low quality. The techniques, type of GIC, type of cavity, and operator experience highly influence clinical performance. Thus, clinical decision-making should be based on the dental practitioner's ability, each case analysis, and the patient's wishes. More evidence is needed to determine which is the best material for definitive restorations in permanent and primary dentition.

Bioactivity and remineralization potential of modified glass ionomer cement: A systematic review of the impact of calcium and phosphate ion release

This systematic review investigates the effectiveness of calcium and phosphate ions release on the bioactivity and remineralization potential of glass ionomer cement (GIC). Electronic databases, including PubMed-MEDLINE, Scopus, and Web of Science, were systematically searched according to PRISMA guidelines. This review was registered in the PROSPERO database. Five eligible studies on modifying GIC with calcium and phosphate ions were included. The risk of bias was assessed using the RoBDEMAT tool. The incorporation of these ions into GIC enhanced its bioactivity and remineralization properties. It promoted hydroxyapatite formation, which is crucial for remineralization, increased pH and inhibited cariogenic bacteria growth. This finding has implications for the development of more effective dental materials. This can contribute to improved oral health outcomes and the management of dental caries, addressing a prevalent and costly oral health issue. Nevertheless, comprehensive longitudinal investigations are needed to evaluate the clinical efficacy of this GIC's modification.

Biomimetic approaches and materials in restorative and regenerative dentistry: review article

Biomimetics is a branch of science that explores the technical beauty of nature. The concept of biomimetics has been brilliantly applied in famous applications such as the design of the Eiffel Tower that has been inspired from the trabecular structure of bone. In dentistry, the purpose of using biomimetic concepts and protocols is to conserve tooth structure and vitality, increase the longevity of restorative dental treatments, and eliminate future retreatment cycles. Biomimetic dental materials are inherently biocompatible with excellent physico-chemical properties. They have been successfully applied in different dental fields with the advantages of enhanced strength, sealing, regenerative and antibacterial abilities. Moreover, many biomimetic materials were proven to overcome significant limitations of earlier available generation counterpart. Therefore, this review aims to spot the light on some recent developments in the emerging field of biomimetics especially in restorative and regenerative dentistry. Different approaches of restoration, remineralisation and regeneration of teeth are also discussed in this review. In addition, various biomimetic dental restorative materials and tissue engineering materials are discussed.

Effect of CPP-ACP Modified-GIC on Prevention of Demineralization in Comparison to Other Fluoride-Containing Restorative Materials

BACKGROUND

This study evaluated the ability of a CPP-ACP-modified GIC to inhibit demineralization around the margin of cervical cavities in natural teeth in comparison with a Giomer and conventional GIC with and without coating.

METHODS

Thirty-two sound human molars were used. Box-shaped cavities were prepared along the CEJ. Teeth were randomly divided into 4 groups and restored with Equia Forte Fil, Coated Equia Forte Fil, Fuji VII EP, or Beautifil II. Teeth were subjected to pH cycling. Micromorphological and elemental analyses were done using SEM and EDX. Polarized light microscope analysis and microhardness tests were also performed.

RESULTS

Microhardness tests on enamel showed a significant difference between the coated Equia group, Equia, and Beautifil II groups (p<0.05). Dentin results showed significant differences between the coated Equia group and all other groups (p<0.05). Elemental analysis showed significant differences in calcium weight percentage among the first and second observation levels in all groups (p<0.05). A significant difference was found between the coated Equia group and the other three groups (p<0.05).

CONCLUSIONS

All tested materials showed some ability to resist demineralization at the restoration margins. The coated GIC restoration showed better outcomes compared with the other tested materials. © 2022 Australian Dental Association.

Synthetic amorphous calcium phosphates (ACPs): preparation, structure, properties, and biomedical applications

Amorphous calcium phosphates (ACPs) represent a metastable amorphous state of other calcium orthophosphates (abbreviated as CaPO₄) possessing variable compositional but rather identical glass-like physical properties, in which there are neither translational nor orientational long-range orders of the atomic positions. In nature, ACPs of a biological origin are found in the calcified tissues of mammals, some parts of primitive organisms, as well as in the mammalian milk. Manmade ACPs can be synthesized in a laboratory by various methods including wet-chemical precipitation, in which they are the first solid phases, precipitated after a rapid mixing of aqueous solutions containing dissolved ions of Ca²⁺ and PO₄^3- in sufficient amounts. Due to the amorphous nature, all types of synthetic ACPs appear to be thermodynamically unstable and, unless stored in dry conditions or doped by stabilizers, they tend to transform spontaneously to crystalline CaPO₄, mainly to ones with an apatitic structure. This intrinsic metastability of the ACPs is of a great biological relevance. In particular, the initiating role that metastable ACPs play in matrix vesicle biomineralization raises their importance from a mere laboratory curiosity to that of a reasonable key intermediate in skeletal calcifications. In addition, synthetic ACPs appear to be very promising biomaterials both for manufacturing artificial bone grafts and for dental applications. In this review, the current knowledge on the occurrence, structural design, chemical composition, preparation, properties, and biomedical applications of the synthetic ACPs have been summarized.

Using Proanthocyanidin as a Root Dentin Conditioner for GIC Restorations

Glass ionomer cements (GICs) are considered the material of choice for restoration of root carious lesions (RCLs). When bonding to demineralized dentin, the collapse of dentinal collagen during restorative treatment may pose challenges. Considering its acidic nature and collagen biomodification effects, proanthocyanidin (PAC) could be potentially used as a dentin conditioner to remove the smear layer while simultaneously acting to biomodify the dentinal collagen involved in the bonding interface. In this study, 6.5% w/v PAC was used as a conditioner for sound (SD) and laboratory demineralized (DD) root dentin before bonding to resin-modified GIC (FII), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified GIC (FVII), or a high-viscosity GIC (FIX). Root dentin conditioned with deionized distilled water (DDW) or polyacrylic acid (PAA) served as controls. Results indicated FII showed higher shear bond strength (SBS) on SD than the other 2 GICs, especially in PAA-conditioned samples; FIX showed significantly higher SBS than FII and FVII on PAA- or PAC-conditioned DD. In each category of GIC, PAA and PAC did not have a significant influence on SBS in most cases compared to DDW except for a significant decrease in PAC-conditioned SD bonded to FII and a significant increase in PAA-conditioned DD bonded to FIX. The bonding interface between GIC and SD was generally more resistant to the acid-base challenge than DD. Although the alterations in failure modes indicated a compromised interfacial interaction between GICs and PAC-treated root dentin, biomodification effects of PAC on dentin were observed from Raman microspectroscopy analysis in terms of the changes in mineral-to-matrix ratio and hydroxyproline-to-proline ratio of dentin adjacent to the bonding interface, especially of DD. Results from this study also indicated the possibility of using in situ characterization such as Raman microspectroscopy as a complementary approach to SBS test to investigate the integrity of the bonding interface.

In-air micro-proton-induced X-ray/gamma-ray emission analysis of the acid resistance of root dentin after applying fluoride-containing materials incorporating calcium

This study employed an in-air micro-proton-induced X-ray/gamma-ray emission system to assess the effectiveness of fluoride-containing materials (FCMs) incorporating calcium in preventing root caries. Dentin surfaces of human third molars were coated with one of three FCMs: fluoride-releasing glass-ionomer cement (F7) and experimental materials in which half (P1) or all (P2) of the strontium in F7 was replaced with calcium. Dentin without FCM coating served as the control. Specimens were immersed in saline at 37°C for 1 month, sectioned, and then demineralized. Calcium loss after demineralization was lower in the Ca-substituted groups than in the Ca-unsubstituted groups (p<0.05). Calcium loss was negatively correlated with fluoride uptake (p<0.01). In the F7, P1, and P2 groups, the retraction of the dentin surface was significantly suppressed as compared with the control group. FCMs incorporating calcium improved the acid resistance of root dentin and could help prevent root caries.

Comparative evaluation of compressive and flexural strength, fluoride release and bacterial adhesion of GIC modified with CPP-ACP, bioactive glass, chitosan and MDPB

Background. This study evaluated the incorporation of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), calcium sodium phosphosilicate bioactive glass (BAG), chitosan (CH), and methacryloyloxydodecylpyridinium bromide (MDPB) on the compressive and flexural strength, fluoride (F^‒ ) release, and bacterial adhesion of conventional glass-ionomer cement (C-GIC).

Methods. Modifications were implemented by adding CPP-ACP, BAG, and CH to the glass powder, while MDPB-GIC was prepared by incorporating MDPB to the liquid of C-GIC. Custom-made molds were used for specimen preparation. Compressive and flexural strengths were evaluated using a universal testing machine. F^‒ release was calculated with Erichrome cyanide reagent, using UV-spectrophotometry, at two time intervals of 24 hours and seven days. For bacterial adhesion, the test specimens were exposed to the bacterial suspension of Streptococcus mutans and Lactobacillus acidophilus for 4 hours, and the adherent bacteria were quantified using colorimetry as the optical density (OD).

Results. The incorporation of MDPB increased the flexural strength of C-GIC, with no effect on its compressive strength. CH significantly improved the compressive and flexural strength; modifications with CPP-ACP, BAG, and MDPB significantly improved the flexural strength of C-GIC. While MDPB-GIC released significantly higher F^‒ at 24 hours, CPP-ACP- and BAG-modified GICs were comparable to C-GIC on day 7. C-GIC exhibited the highest bacterial adhesion, and MDPB-GIC showed the least. The data were analyzed with one-way (ANOVA), and pairwise comparisons were made with Tukey HSD tests.

Conclusion. Hence, it can be concluded that the incorporation of CPP-ACP, BAG, and CH improved the mechanical properties of C-GIC, whereas MDPB improved the resistance of C-GIC to bacterial adhesion.

Current aspects and prospects of glass ionomer cements for clinical dentistry

Glass ionomer cement (GIC) is a tailor-made material that is used as a filling material in dentistry. GIC is cured by an acid-base reaction consisting of a glass filler and ionic polymers. When the glass filler and ionic polymers are mixed, ionic bonds of the material itself are formed. In addition, the extra polymer anion reacts with calcium in enamel or dentin to increase adhesion to the tooth tissue. GICs are widely used as adhesives for artificial crowns or orthodontic brackets, and are also used as tooth repair material, cavity liner, and filling materials. In this review, the current status of GIC research and development and its prospects for the future have been discussed in detail.

A review on dental whitening

OBJECTIVES

To provide a narrative review on vital dental whitening chemistry, toxicity and safety, vital dental whitening techniques, whitening systems, potential side effects of whitening and cyclic whitening using products with a range of concentrations and pH values. In addition, new developments and recommendations in the field of vital dental whitening will be presented to help clinicians understand the whitening process, its advantages, limitations, and the impact of whitening concentration and pH on enamel providing guidance in tailoring whitening treatments.

DATA

Data were gathered using the following keywords: dental whitening, roughness, hardness, sensitivity, hydrogen peroxide, whitening pH, whitening concentration, whitening chemistry, colour, and toxicity.

SOURCES

An electronic search was performed using PubMed and Scopus databases. Bibliographic material from papers reviewed was then used to find other relevant publications.

CONCLUSIONS

The effectiveness of vital dental whitening depends on many factors, such as the concentration/pH of the whitening agent, application duration, chemical additives, and re-mineralising agents used. Developing new whitening products and technologies such as nano-additives and alternative carrier systems is showing promising results, and might prove efficient in maximising whitening benefits by accelerating the whitening reaction and/or minimising expected reversible/irreversible enamel structural damage.

The synergistic effects of SrF2 nanoparticles, YSZ nanoparticles, and poly-ε-l-lysin on physicomechanical, ion release, and antibacterial-cellular behavior of the flowable dental composites

Resin-based pit-and-fissure sealants (flowable resin composites) were formulated using bisphenol-A-glycerolatedimethacrylate (Bis-GMA)-triethylene glycol dimethacrylate-(TEGDMA)-diurethanedimethacrylate (UDMA) mixed monomers and multiple fillers, including synthetic strontium fluoride (SrF₂) nanoparticles as a fluoride-releasing and antibacterial agent, yttria-stabilized zirconia (YSZ) nanoparticles as an auxiliary filler, and poly-ε-l-lysin (ε-PL) as an auxiliary antibacterial agent. Based on the physical, mechanical and initial antibacterial properties, the formulated nano-sealant containing 5 wt% SrF₂, 5 wt% YSZ and 0.5 wt% ε-PL was selected as the optimal specimen and examined for ion release and cytotoxicity. The results showed an average release rate of 0.87 μg·cm^-2·day^-1 in the aqueous medium (pH 6.9) and 1.58 μg·cm^-2·day^-1 in acidic medium (pH 4.0). The maximum cytotoxicity of 20% toward human bone marrow mesenchymal stem cells (hMSCs) was observed according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) cytotoxicity assay and acridine orange staining test. A synergy between SrF₂ nanoparticles and ε-PL exhibited a better antibacterial activity in terms of colony reduction compared to the other samples. However, the inclusion of SrF₂ and ε-PL caused mechanically weakening of the sealants that was partly compensated by incorporation of YSZ nanoparticles (up to 10 wt%).

Resin-modified glass ionomer containing calcium glycerophosphate: physico-mechanical properties and enamel demineralization

Sources of calcium and phosphate have been added to dental restorative materials to improve their anticaries effect.

Effect of casein phosphopeptide-amorphous calcium phosphate on fluoride release and micro-shear bond strength of resin-modified glass ionomer cement in caries-affected dentin

Objectives

This study was conducted to evaluate fluoride release and the micro-shear bond strength of resin-modified glass ionomer cement (RMGIC) in casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-remineralized caries-affected dentin (CAD).

Materials and Methods

Exposed dentin surfaces of 30 human third molar teeth were divided into 2 equal groups for evaluating fluoride release and the micro-shear bond strength of RMGIC to CAD. Each group was subdivided into 3 equal subgroups: 1) control (sound dentin); 2) artificially demineralized dentin (CAD); 3) CPP-ACP remineralized dentin (remineralized CAD). To measure fluoride release, 15 disc-shaped specimens of RMGIC (4 mm in diameter and 2 mm in thickness) were bonded on one flat surface of the dentin discs of each group. Fluoride release was tested using ion chromatography at different intervals; 24 hours, 3, 5, 7 days. RMGIC micro-cylinders were built on the flat dentin surface of the 15 discs, which were prepared according to the assigned group. Micro-shear bond strength was measured after 24 hours water storage. Data were analyzed using 1- and 2-way analysis of variance and the post hoc least significant difference test (α = 0.05).

Results

Fluoride detected in solutions (at all intervals) and the micro-shear bond strength of RMGIC bonded to CPP-ACP-remineralized dentin were significantly higher than those bonded to artificial CAD (p < 0.05).

Conclusions

Demineralized CAD consumes more fluoride released from RMGIC into the solution for remineralization than CPP-ACP mineralized dentin does. CPP-ACP increases the micro-shear bond strength of RMGIC to CAD.

Calcium Charge and Release of Conventional Glass-Ionomer Cement Containing Nanoporous Silica

The aim of this study was to evaluate calcium charge and release of conventional glass-ionomer cement (GIC) containing nanoporous silica (NPS). Experimental specimens were divided into two groups: the control (GIC containing no NPS) and GIC-NPS (GIC containing 10 wt % NPS). The specimens were immersed in calcium chloride solutions of 5 wt % calcium concentration for 24 h at 37 °C, whereupon the calcium ion release of the specimens was measured. The calcium ion release behavior of GIC-NPS after immersion in the calcium solution was significantly greater than that of the control. Scanning electron microscopy and electron-dispersive X-ray spectroscopy results indicated that calcium penetrated inside the GIC-NPS specimen, while the calcium was primarily localized on the surface of the control specimen. It was demonstrated that NPS markedly improved the calcium charge and release property of GIC.

Microtensile bond strength of resin cement primer containing nanoparticles of silver (NAg) and amorphous calcium phosphate (NACP) to human dentin

PURPOSE

The purpose of the current study was to evaluate the effect of incorporating nanoparticles of silver (NAg) and amorphous calcium phosphate (NACP) into a self-etching primer of a resin cement on the microtensile bond strength of dentin, regarding the proven antibacterial feature of NAg and remineralizing effect of NACP.

MATERIALS AND METHODS

Flat, mid-coronal dentin from 20 intact extracted human third molars were prepared for cementation using Panavia F2.0 cement. The teeth were randomly divided into the four test groups (n=5) according to the experimental cement primer composition: cement primer without change (control group), primer with 1% (wt) of NACP, primer with 1% (wt) of physical mixture of NACP+Nag, and primer with 1% (wt) of chemical mixture of NACP+Nag. The resin cement was used according to the manufacturer's instructions. After storage in distilled water at 37℃ for 24 h, the bonded samples were sectioned longitudinally to produce 1.0 × 1.0 mm beams for micro-tensile bond strength testing in a universal testing machine. Failure modes at the dentin-resin interface were observed using a stereomicroscope. The data were analyzed by one-way ANOVA and Tukey's post-hoc tests and the level of significance was set at 0.05.

RESULTS

The lowest mean microtensile bond strength was obtained for the NACP group. Tukey's test showed that the bond strength of the control group was significantly higher than those of the other experimental groups, except for group 4 (chemical mixture of NACP and NAg; P=.67).

CONCLUSION

Novel chemical incorporation of NAg-NACP into the self-etching primer of resin cement does not compromise the dentin bond strength.

Shear Bond Strength and Remineralisation Effect of a Casein Phosphopeptide-Amorphous Calcium Phosphate-Modified Glass Ionomer Cement on Artificial "Caries-Affected" Dentine

This study investigated the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified glass ionomer cement (GIC) on shear bond strength (SBS) and remineralisation of artificial “caries-affected” dentine. Human dentine slices were demineralised and allocated to three groups: group 1, conventional GIC; group 2, CPP-ACP-modified GIC; and group 3, resin-modified GIC. The SBS was measured using a universal testing machine (n = 16 per group). Remaining samples (n = 8 per group) were subjected to pH-cycling for 28 days. After pH-cycling, lesion depth and micro-mechanical properties at the sample-bonding interface were investigated using micro-computed tomography (micro-CT) and nano-indentation, respectively. The SBS for groups 1 to 3 were 4.6 ± 1.5 MPa, 4.2 ± 1.1 MPa, and 5.9 ± 1.9 MPa, respectively (p = 0.007; group 1, group 2 < group 3). Lesion depths determined by micro-CT for groups 1 to 3 were 186 ± 8 µm, 149 ± 14 µm, and 178 ± 8 µm, respectively (p < 0.001; group 2 < group 1, group 3). The mean (±SD, standard deviation) nano-hardness values for groups 1 to 3 were 0.85 ± 0.22 GPa, 1.14 ± 0.21 GPa, and 0.81 ± 0.09 GPa, respectively (p = 0.003; group 1, group 3 < group 2). The mean (±SD) elastic moduli for groups 1 to 3 were 1.70 ± 0.33 GPa, 2.35 ± 0.44 GPa, and 1.59 ± 0.13 GPa, respectively (p < 0.001; group 1, group 3 < group 2). The results suggest that the incorporation of CPP-ACP into GIC does not adversely affect the adhesion to artificial caries-affected dentine. Furthermore, CPP-ACP-modified GIC is superior to conventional GIC in promoting dentine remineralisation.

Nanochitosan modified glass ionomer cement with enhanced mechanical properties and fluoride release

Conventional glass-ionomer cements (GIC) are one of the most prevalent dental restorative materials, but their use is limited by their relatively low mechanical strength. Efforts have been made to improve the mechanical properties by addition of various fillers of which nano-sized particles appears to be a promising strategy. In the current study, effect of addition of nanochitosan particles in GIC (NCH-GIC) on compressive strength, flexural strength, wear resistance and fluoride release has been evaluated and compared with conventional GIC (C-GIC). Nanochitosan was synthesized by ionic cross linking method and its particle size was found to be 110-235nm. Nanochitosan was mixed with glass ionomer powder at a concentration of 10wt.% and cement samples were prepared. NCH-GIC had significantly higher compressive strength values which could be attributed to early formation of aluminium polysalts. Similarly, flexural strength of NCH-GIC (21.26MPa) was significantly higher than C-GIC (12.67MPa). Wear resistance was also found to increase due to better integrated interface between the glass particle and polymer matrix bonding in NCH-GIC. Fluoride release was significantly higher in NCH-GIC compared to C-GIC for 7 days. It can be anticipated that addition of nanochitosan to GIC will improve the anti-cariogenic and mechanical properties for high strength applications.

Incorporation of CPP-ACP into Luting and Lining GIC: Influence on Wear Rate (in the Presence of Artificial Saliva) and Compressive Strength

The improvement of mechanical and antibacterial properties of glass ionomer cements (GICs) is an important goal in dental research. In this way, modification of GIC with caries preventive and remineralizing materials such as casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is a new strategy to enhance its anticariogenic properties and the remineralization of teeth. However, one main concern is that adding CPP-ACP may have negative effects on the mechanical properties of GIC. This study investigated the influence of adding CPP-ACP on the wear rate (in the presence of artificial saliva) and compressive strength of luting and lining glass ionomer cement. CPP-ACP was incorporated into a luting and lining glass ionomer cement at different percentages (1, 1.56, and 2%). Wear rate and compressive strength were measured for each group using Pin-on-Disk tribometer device (in artificial saliva condition) and universal testing machine, respectively. The wear test was carried out in the presence of artificial saliva for better simulation of the oral environment. Our results demonstrated that increasing the percentage of CPP-ACP from 0 up to 1.56% (w/w), caused a decrease of 19% in the wear rate. However, at 2% (w/w) CPP-ACP, the wear rate increased. Compressive strength was improved by 31% when the CPP-ACP concentration was increased to 1.56% (w/w), but decreased when the concentration was raised to 2% (w/w). In conclusion, adding 1.56% CPP-ACP into luting and lining glass ionomer cement appears to provide an acceptable combination of two important mechanical properties, compressive strength and wear rate.

Effect of surface treatments on the mechanical properties and antimicrobial activity of desiccated glass ionomers

OBJECTIVES

The purpose of this study was to evaluate the effect of various surface treatments on the mechanical properties and antibacterial activity of desiccated glass-ionomer (GI) and resin-modified glass-ionomer (RMGI) materials.

METHODS

One hundred GI and RMGI specimens were fabricated in a mold, stored in 100% humidity for 24h, placed in air to desiccate for 24h, and then stored for one week in one of the five media [casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), chlorhexidine (CHX), sodium fluoride (NaF), cetylpyridinium chloride (CPC), or 100% humidity (control)]. Fifty GI and RMGI specimens were tested in flexure to determine flexural strength and modulus, with the fragments used for Knoop hardness testing. The remaining 50 GI and RMGI specimens were covered with a suspension of Streptococcus mutans and incubated for 24h. The bacterial suspension was removed and the specimens were washed. Sterile saline was added, vortex mixed, serially diluted, and plated. CFU/mLs were calculated after 3days of incubation.

RESULTS

Compared to the 100% humidity control group, surface treatment of the desiccated GI and RMGI materials had a variable effect on the mechanical properties. In general, NaF provided the greatest improvement in flexural strength and modulus. Surface treatment of the desiccated GI or RMGI specimens with CHX or CPC resulted in no growth of the S. mutans. NaF resulted in significantly lower CFU/mL than CPP-ACP, which was significantly lower than the control group.

SIGNIFICANCE

Surface treatment with 5% NaF provides improved antimicrobial and strength properties of desiccated GI or RMGI materials.

Antimicrobial Capacity of Casein Phosphopeptide/Amorphous Calcium Phosphate and Enzymes in Glass Ionomer Cement in Dentin Carious Lesions

OBJECTIVE

To evaluate the ability of casein phosphopeptide/amorphous calcium phosphate (CPP/ACP) and lysozyme, lactoferrin, and lactoperoxidase (LLL) added to glass ionomer cement (GIC) to inhibit the growth of S. mutans in a caries model.

MATERIAL AND METHODS

Eighty permanent third molars were selected. The dentin of these teeth was exposed and flattened. Except for the coronal dentin, the specimens were waterproofed, autoclaved, and submitted to cariogenic challenge with standard strain of S. mutans. The carious lesions were sealed as follows: group 1 (n=20): GIC without additives; group 2 (n=20): GIC + CPP/ACP; group 3 (n=20): GIC + LLL; group 4 (n=20): GIC + CPP/ACP + LLL. S. mutans counts were performed before the caries were sealed (n=5), after 24 hours (n=5), at 1 month (n=5), and at 6 months (n=5). The results were analyzed using descriptive statistical analysis and the Kruskal-Wallis test (Student-Newman-Keuls test).

RESULTS

GIC + LLL caused a significant reduction of S. mutans 1 month after sealing (p<0.01); however, there was a significant growth of S. mutans 6 months after sealing. GIC, GIC + CPP/ACP, and GIC + CPP/ACP + LLL showed similar behavior with significant reduction of S. mutans after 24 hours (p<0.05) and increase after 1 and 6 months.

CONCLUSION

The addition of LLL to GIC increases the antimicrobial action of GIC on S. mutans. This leads to control of bacterial biofilm for 1 month, thus stopping the progression of carious lesions.

Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms

Glass ionomer cements (GIC) are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm) formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

Analysis of anticaries potential of pit and fissures sealants containing amorphous calcium phosphate using synchrotron microtomography

The aim of this study was to analyze the anticaries potential of pit and fissure sealants containing amorphous calcium phosphate (ACP) by synchrotron microtomography. Bovine enamel blocks (4×4 mm; n=50) were selected through surface hardness (Knoop) analysis. Slabs were obtained through cross-sections taken 1 mm from the border of the enamel. Five indentations, spaced 100 μm apart, were made 300 μm from the border. Ten specimens were prepared for each tested material (Ultraseal XT plus TM, Aegis, Embrace, Vitremer and Experimental Sealant). The materials were randomly attached to the sectioned surfaces of the enamel blocks and fixed with sticky wax. The specimens were submitted to pH cycling. After that, the surface hardness (SH1) was determined, and the blocks were submitted to synchrotron microcomputed tomography analysis to calculate the mineral concentration (ΔgHAp cm(-3)) at different areas of the enamel. The comparison between the SH1 and ΔgHAp cm(-3) showed a correlation for all groups (r=0.840; p<0.001). The fluoride groups presented positive values of ΔgHAp cm(-3), indicating a mineral gain that was observed mainly in the outer part of the enamel. The ACP showed mineral loss in the outer enamel compared with fluoride groups, although it inhibited the demineralization in the deeper areas of enamel. The combination of two remineralizing agents (fluoride and ACP) was highly effective in preventing demineralization.

Protective potential of casein phosphopeptide amorphous calcium phosphate containing paste on enamel surfaces

Background:

Dental caries remains the most common dental disease facing mankind. Prevention of initiation and interruption in progression of early lesions are the desirable modes of caries management. There is a scope for agents, which may be used to enhance anti - caries activity. This need has redirected research to develop novel preventive agents that can act as an adjunct to fluoride or independent of it. Casein Phosphopeptide – Amorphous Calcium Phosphate (CPP-ACP) is one such agent that has been proposed to have anti cariogenic properties.

Aim:

The purpose of this in vitro study was to evaluate the effect of paste containing CPP-ACP, MI Paste, on enamel remineralization.

Materials and Methods:

This study consisted of 30 samples embedded in orthodontic resin with either the buccal or lingual surface exposed. The samples were assigned to either a CPP-ACP containing paste; Fluoridated toothpaste; or a control group. The groups were then subjected to cycling in a demineralizing solution and a remineralizing solution. Groups II and III received prior application of MI paste and Fluoridated toothpaste respectively followed by cycling in a demineralizing solution and a remineralizing solution. Following 14 days of cycling, the samples were sectioned and examined using confocal microscopy. The lesion depth, were evaluated.

Statistical Analysis:

Image Proplus software was used to analyze the images. The values were statistically evaluated using one – way ANOVA and Scheffe's Test.

Results and Conclusion:

Within the limitations of the study it was concluded that enamel surfaces treated with the CPP-ACP paste exhibited the least lesion depths followed by the enamel surfaces treated with the fluoridated tooth paste and control group respectively.

Evaluation of the Microleakage of Chlorhexidine-Modified Glass Ionomer Cement: An in vivo Study

AIM

Recent advances including the incorporation of antibacterial substances, such as chlorhexidine, into restorative materials such as glass ionoer cement (GIC), might alter the physical properties of the material, which might affect the marginal seal of the restorations. Hence, the objective of this study was to compare the marginal sealing ability of GC Fuji IX modified with 1% chlorhexidine diacetate and conventional GC Fuji IX.

MATERIALS AND METHODS

Sixty healthy molars were selected from the oral cavities of 30 children. The teeth were divided into two groups: Group I, teeth restored with 1% chlorhexidine diacetate modified GC Fuji IX and group II, teeth restored with GC Fuji IX. The restored teeth were extracted following 4 weeks and immersed in 2% basic fuchsin solution for 24 hours. They were then sectioned and scored under a light microscope of 10 × 10 magnification for dye penetration.

RESULTS

On statistical analysis difference between Chlorhexidine-Modified GIC group and GIC group with regard to grade of microleakage was found to be statistically nonsignificant (p = 0.543).

CONCLUSION

Since, addition of 1% chlorhexidine diacetate to GC Fuji IX showed comparable results with regard to microleakage, it can be considered a valuable alternative especially in atraumatic restorative treatment and for general clinical utility in restorative dentistry. How to cite this article: Mathew SM, Thomas AM, Koshy G, Dua K. Evaluation of the Microleakage of Chlorhexidine-Modified Glass Ionomer Cement: An in vivo Study. Int J Clin Pediatr Dent 2013;6(1):7-11.

Caries preventive effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP): a meta-analysis

OBJECTIVE

This systematic review with meta-analyses sought to answer the following question: "Does CPP-ACP [casein phosphopeptide-amorphous calcium phosphate], when introduced into the oral environment, provide any caries-preventive benefit superior to that of any other intervention or placebo?"

MATERIAL AND METHODS

Seven electronic databases were searched for trials relevant to the review question. Twelve articles were accepted after application of inclusion and exclusion criteria.

RESULTS

Of the accepted articles, five in situ randomized control trials (RCT) could be pooled for meta-analyses. During the short-term (7-21 days) in situ trials, participants wore appliances containing enamel slabs that were analyzed in the laboratory after exposure to CPP-ACP. The pooled in situ results showed a weighted mean difference (WMD) of the percentage remineralization scores in favor of chewing gum with 18.8 mg CPP-ACP as compared to chewing gum without CPP-ACP (WMD -8.01; 95% CI: -10.54 to -5.48; p = 0.00001), as well as compared to no intervention (WMD -13.56; 95% CI: -16.49 to -10.62; p = 0.00001). A significant higher remineralization effect was also observed after exposure to 10.0 mg CPP-ACP (-7.75; 95% CI: -9.84 to -5.66; p = 0.00001). One long-term in vivo RCT (24 months) with a large sample size (n = 2720) found that the odds of a tooth surface's progressing to caries was 18% less in subjects who chewed sugar-free gum containing 54 mg CPP-ACP than in control subjects who chewed gum without CPP-ACP (p = 0.03).

CONCLUSION

Within the limitations of this systematic review with meta-analysis, the results of the clinical in situ trials indicate a short-term remineralization effect of CPP-ACP. Additionally, the promising in vivo RCT results suggest a caries-preventing effect for long-term clinical CPP-ACP use. Further randomized control trials are needed in order to confirm these initial results in vivo.

Comparison of effect of desensitizing agents on the retention of crowns cemented with luting agents: an in vitro study

PURPOSE

Many dentists use desensitizing agents to prevent hypersensitivity. This study compared and evaluated the effect of two desensitizing agents on the retention of cast crowns when cemented with various luting agents.

MATERIALS AND METHODS

Ninety freshly extracted human molars were prepared with flat occlusal surface, 6 degree taper and approximately 4 mm axial length. The prepared specimens were divided into 3 groups and each group is further divided into 3 subgroups. Desensitizing agents used were GC Tooth Mousse and GLUMA® desensitizer. Cementing agents used were zinc phosphate, glass ionomer and resin modified glass ionomer cement. Individual crowns with loop were made from base metal alloy. Desensitizing agents were applied before cementation of crowns except for control group. Under tensional force the crowns were removed using an automated universal testing machine. Statistical analysis included one-way ANOVA followed by Turkey-Kramer post hoc test at a preset alpha of 0.05.

RESULTS

Resin modified glass ionomer cement exhibited the highest retentive strength and all dentin treatments resulted in significantly different retentive values (In Kg.): GLUMA (49.02 ± 3.32) > Control (48.61 ± 3.54) > Tooth mousse (48.34 ± 2.94). Retentive strength for glass ionomer cement were GLUMA (41.14 ± 2.42) > Tooth mousse (40.32 ± 3.89) > Control (39.09 ± 2.80). For zinc phosphate cement the retentive strength were lowest GLUMA (27.92 ± 3.20) > Control (27.69 ± 3.39) > Tooth mousse (25.27 ± 4.60).

CONCLUSION

The use of GLUMA® desensitizer has no effect on crown retention. GC Tooth Mousse does not affect the retentive ability of glass ionomer and resin modified glass ionomer cement, but it decreases the retentive ability of zinc phosphate cement.

Anti-genotoxic potential of casein phosphopeptides (CPPs): a class of fermented milk peptides against low background radiation and prevention of cancer in radiation workers

BACKGROUND

Radiation workers are constantly exposed to low background radiation which is their occupational hazard. This continuous and prolonged exposure produces genotoxicity and cancerous condition in many workers. The authors have tested casein phosphopeptides (CPP) as a radioprotectant against low background radiation using animal models.

METHODS

Fermented milk was produced by addition of a bacterial culture, Lactobacillus acidophilus to a commercially available milk brand. After the fermentation process is completed in the milk, CPP is isolated from fermented milk by enzymatic hydrolysis-based method. The radioprotective role of CPP was proved using albino mice and Catla catla fish.

RESULTS

The micronucleus assay showed higher level of cell deformation and micronucleus formation in the control animal cells than the test animal cells. CPP has found to be having radioprotective activity potential.

CONCLUSIONS

This radioprotective potential of CPP can be harnessed to produce formulations which can be used by radiation workers and personnel exposed to low ionization background as an occupational hazard, thus reducing the risk and preventing any type of cancer.

Influence of Salvadora persica (miswak) extract on physical and antimicrobial properties of glass ionomer cement

AIM

To investigate physical and antimicrobial properties of Glass Ionomer Cement (GIC) combined with Salvadora Persica Extract (SPE).

METHODS

SPE was added to GIC (Fuji IX) in concentrations of 1%, 2% and 4% w/w. The compressive strength and diametral tensile strength were measured at 1 h, 24 h and 7 days. The antimicrobial effect was tested in agar dilution assay in blood agar plates with Candida albicans, Streptococcus mutans, Streptococcus sanguis, Streptococcus mitis, Streptococcus salivarius and Actinomyces naeslundii as test organisms. GIC containing 5% chlorhexidine served as positive control.

RESULTS

Significant differences were found for the compressive strength and diametral tensile strength as a result of adding SPE to GIC (p<0.05). GIC with 2 or 4 % SPE was significantly weaker than the GIC control, while GIC with 1% SPE was not different from the control. The mean values for the 4% SPE-containing specimens and the GIC control group ranged from 108.7MPa to 141.1MPa for CS and from 8.2MPa to 12.5MPa for DTS. The 1% SPE-containing specimens were not different in physical properties compared to the control GIC specimens; the 2% SPE-containing specimens were statistically slightly less strong (p<0.05), but within an acceptable range. As compared with pure GIC the antimicrobial properties of the SPE-containing specimens were increased significantly (p<0.01). It has been found up to a 2-fold increased inhibition compared to the GIC with increasing concentrations of SPE. For most microorganisms tested the SPE group inhibited less than Chlorhexidine, but significantly better than pure GIC (p<0.01).

CONCLUSION

SPE could be a promising natural material as an additive to GICs. Further studies should include in vivo tests and other antimicrobial and physical properties of this combination.

Self-reparability of glass-ionomer cements: an in vitro investigation

Despite the advantages of glass-ionomer cement (GIC) restorative materials, they exhibit low mechanical properties and are susceptible to dissolution. The purpose of this study was to investigate the existence of self-reparability of a GIC material. Thirty Fuji IX discs were fabricated and subjected to desiccation. The discs were randomly separated into three groups: one group was kept in air, a second group was soaked in water, and a third group was placed in casein phosphoprotein-amorphous calcium phosphate-containing solution (Dentacal; NSI, Hornsby, Australia). After 21 d of incubation, all specimens were subjected to biaxial flexure testing. One-way ANOVA revealed a statistical difference in the biaxial flexure strength between the groups. Weibull statistics revealed that the Dentacal group demonstrated a lower probability of failure than the other groups. The air group exhibited the highest probability of failure. The difference between the specimens was expected as a result of enhanced cross-linking between the polyalkenoate chains and the GIC particles, and the diffusion of ionic components to the set GIC. Therefore, perhaps a form of reparative mechanism exists for precrazed GIC when it is exposed to a remineralizing solution. In addition to the benefit on natural tooth structures, this study indicates that remineralizing solutions are also beneficial for maintaining the mechanical integrity of GIC restorations.

Amorphous Calcium Phosphates

Amorphous calcium phosphates (ACPs) represent a unique class of biomedically relevant calcium orthophosphate salts, in which there are neither translational nor orientational long-range orders of the atomic positions. Nevertheless, the constancy in their chemical composition over a relatively wide range of preparation conditions suggests the presence of a well-defined local structural unit, presumably, with the structure of Ca9(PO4)6 – so-called Posner’s cluster. ACPs have variable chemical but rather identical glass-like physicochemical properties. Furthermore, all ACPs are thermodynamically unstable compounds and, unless stored in dry conditions or doped by stabilizers, spontaneously they tend to transform to crystalline calcium orthophosphates. Although some order within general disorder is the most distinguishing feature of ACPs, the solution instability of ACPs and their easy transformation to crystalline phases might be of a great biological relevance. Namely, the initiating role ACPs play in matrix vesicle biomineralization raises the importance of this phase from a mere laboratory curiosity to that of a key intermediate in skeletal calcification. Furthermore, ACPs are very promising candidates to manufacture artificial bone grafts.