Characterization of oral films formed in the presence of a CPP–ACP agent: An in situ study

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.

Shear bond strength of metallic brackets bonded to enamel pretreated with CPP-ACP: a systematic review and meta-analysis of in vitro studies

BACKGROUND

Development of white spot lesions (WSLs) is common among orthodontic patients. Several measures have been introduced to prevent and remineralize the lesions. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is used for both prevention and remineralization. The effect of its application before bonding is controversial. This systematic review was conducted to investigate the most up to date available literature regarding the effect of CPP-ACP enamel pre-treatment on shear bond strength (SBS) of metallic orthodontic brackets.

METHODS

A search was conducted in electronic databases (MEDLINE (via PubMed), Scopus, Cochrane Library, Web of Science and Google scholar (grey literature)) up to March 29th, 2023. The inclusion criteria included in vitro studies comparing the SBS of metal orthodontic brackets following pre-treatment of enamel using CPP-ACP versus control. The exclusion criteria included study types other than in vitro studies, studies conducted on non-human enamel, or studies using CPP-ACP in combination with another intervention. The included studies were analysed by two reviewers, independently. The risk of bias assessment was done using a modified risk of bias tool. A Meta-analysis was performed. I2 values and Q-test were used for assessment of heterogeneity. Results were displayed in forest plots with a random-effects model. Standardized mean difference, standard error (SE) and 95% confidence intervals were calculated for all studies.

RESULTS

The search resulted in 76 articles. After duplicate removal and assessment for eligibility, 15 studies were included in the review. High statistical heterogeneity was found among the included studies using I2 values and Q-Test (I2 = 95.147%; Q = 288.456; df = 14; P < 0.001). The overall effect of CPP-ACP pre-treatment on the SBS of metal orthodontic brackets was not significant (Mean difference = 1.163 MPa, SE = 0.757, 95% CI = -0.321, 2.648, p value = 0.125). The use of CPP-ACP for prevention of WSLs did not significantly affect the SBS of brackets (Standardized mean difference = 1.009, SE = 0.884, 95% CI = -0.723, 2.740, p value = 0.254). No significant change was found when CPP-ACP was used for remineralization of WSLs (Standardized mean difference = 1.501, SE = 1.087, 95% CI = -0.630, 3.632, p value = 0.167).

CONCLUSIONS

Within the limitations of the study, the evidence suggests that the use of CPP-ACP for either prevention or remineralization of WSLs before bonding does not affect the SBS of metal orthodontic brackets.

Tooth mousse containing casein phosphopeptide-amorphous calcium phosphate prevents biofilm formation of Streptococcus mutans

BACKGROUND

Streptococcus mutans is a common cariogenic bacterium in the oral cavity involved in plaque formation. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been introduced into tooth mousse to encourage remineralization of dental enamel. The aim of this research was to study the effect of tooth mousse containing CPP-ACP (GC Tooth Mousse®) or CPP-ACP with 0.2% fluoride (CPP-ACPF; GC Tooth Mousse Plus®; GCP) on S. mutans planktonic growth and biofilm formation.

METHODS

S. mutans was cultivated in the presence of different dilutions of the tooth mousse containing CPP-ACP or CPP-ACPF, and the planktonic growth was determined by ATP viability assay and counting colony-forming units (CFUs). The resulting biofilms were examined by crystal violet staining, MTT metabolic assay, confocal laser scanning microscopy (CLSM), and scanning electron microscope (SEM).

RESULTS

The CPP-ACP tooth mousse (GC) at a dilution of 5-50 mg/ml (0.5-5%) did not inhibit planktonic growth, and even increased the ATP content and the number of viable bacteria after a 24 h incubation. The same was observed for the CPP-ACPF tooth mousse (GCP), except for the higher concentrations (25 and 50 mg/ml) that led to a drop in the bacterial count. Importantly, both compounds significantly decreased S. mutans biofilm formation at dilutions as low as 1.5-3 mg/ml. 12.5 mg/ml GC and 6.25 mg/ml GCP inhibited biofilm formation by 90% after 4 h. After 24 h, the MBIC90 was 6.25 mg/ml for both. CLSM images confirmed the strong inhibitory effect GC and GCP had on biofilm formation when using 5 mg/ml tooth mousse. SEM images of those bacteria that managed to form biofilm in the presence of 5 mg/ml tooth mousse, showed alterations in the bacterial morphology, where the streptococci appear 25-30% shorter on the average than the control bacteria.

CONCLUSION

Our data show that the tooth mousse containing CPP-ACP reduces biofilm formation of the cariogenic bacterium S. mutans without killing the bacteria. The use of natural substances which inhibit biofilm development without killing the bacteria, has therapeutic benefits, especially in orthodontic pediatric patients.

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.

Effect of CPP-ACP on remineralization of artificial caries-like lesion: an in situ study

The purpose of this double-blind, randomized, crossover in situ study is to compare remineralization of preformed enamel lesions by casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) and fluoride dentifrice products. During each of four 10-day experimental legs, 10 participants wore intraoral removable palatal acrylic appliances with four human enamel slabs with preformed lesions. A 0.03-mL treatment paste was dripped extraorally onto the enamel blocks once a day for 3 min. The four randomly allocated treatments were as follows: CO- Control: silica dentifrice without fluoride; MP: MI Paste; MPP: MI Paste Plus and FD: Fluoride dentifrice - 1100 ppm F as NaF). Knoop surface hardness (SH) test was performed in three stages (T0 - sound enamel, T1 - after preformed lesion, and T2 - after treatment) and the cross-sectional hardness (CSH) test was performed after treatment using a 50-gram Knoop load for 15 s. Knoop hardness number (KHN) was similar between treatments. %SHr was significantly higher in the MP, FD, and MPP when compared to CO group (Kruskal-Wallis and Mann-Whitney tests, p < 0.05). Harder enamel was found in MP (75 μm) and FD groups at 75 to 175 μm. Treatment with DF, MP, and MPP promoted an increase of 20.27%, 19.24%, and 14.71%, respectively, in Integral Hardness Change (ΔIHC) when compared to CO (p<0.05). Remineralizing agents (MP, MPP, and DF) were able to inhibit demineralization of human enamel subjected to high cariogenic challenge in situ. DF had the greatest preventive potential against the progression of carious lesions.

Nanoparticles for the Treatment of Oral Biofilms: Current State, Mechanisms, Influencing Factors, and Prospects

Due to their excellent size, designability, and outstanding targeted antibacterial effects, nanoparticles have become a potential option for controlling oral biofilm-related infections. However, the formation of an oral biofilm is a dynamic process, and factors affecting the performance of antibiofilm treatments are complex. As such, when examining the existing literature on the antibiofilm effects of nanoparticles, attention should be paid to the specific mechanisms of action at different stages of oral biofilm formation, as well as relevant influencing factors, in order to achieve an objective and comprehensive evaluation. This review is intended to detail the antibacterial mechanisms of nanoparticles during the four stages of the formation of oral biofilms: 1) acquired film formation; 2) bacterial adhesion; 3) early biofilm development; and 4) biofilm maturation. In addition, factors influencing the antibiofilm properties of nanoparticles are summarized from the aspects of nanoparticles themselves, biofilm models, and host factors. The limitations of current research and possible trends for future research are also discussed. In summary, nanoparticles are a promising antioral biofilm strategy. It is hoped that this review can serve as a reference and inspire ideas for further research on the application of nanoparticles for effectively targeting and treating oral biofilms.

Effect of CPP-ACP on Streptococcus mutans in saliva of high caries-risk preschool children: a randomized clinical trial

PURPOSE

The aim of this study was to assess the efficacy of CPP-ACP in reducing salivary S. mutans levels and compare its effect as a dentifrice to use of a fluoride dentifrice alone, or with the sequential use of a combination of both agents (fluoride, then CPP-ACP) in three groups of preschool children over a 6-month period.

METHODS

This was a double-blinded clinical trial, the sample (n = 127, age 4.6 ± 0.47 years), with high caries risk, was randomized into three groups which applied different agents twice daily; fluoride toothpaste (500 ppm, n = 50), CPP-ACP (10% w/v, n = 38), and combination group (n = 39) applied fluoride, then CPP-ACP. S. mutans salivary levels were measured by GC Saliva-Check Mutans^™.

RESULTS

Within groups, a significant decrease in S. mutans-positive children (SMPC) occurred in fluoride and combination groups at 3-months, (P < 0.05), and in all groups at 6-months, (P < 0.05). The highest reduction in SMPC occurred in the CPP-ACP group, however, there were no significant differences in SMPC between groups at all study intervals, (P > 0.05).

CONCLUSION

Although all agents were effective, CPP-ACP showed the highest reduction in SMPC over 6-months.

Calcium phosphate nanoparticles as intrinsic inorganic antimicrobials: In search of the key particle property

One of the main goals of materials science in the 21st century is the development of materials with rationally designed properties as substitutes for traditional pharmacotherapies. At the same time, there is a lack of understanding of the exact material properties that induce therapeutic effects in biological systems, which limits their rational optimization for the related medical applications. This study sets the foundation for a general approach for elucidating nanoparticle properties as determinants of antibacterial activity, with a particular focus on calcium phosphate nanoparticles. To that end, nine physicochemical effects were studied and a number of them were refuted, thus putting an end to frequently erred hypotheses in the literature. Rather than having one key particle property responsible for eliciting the antibacterial effect, a complex synergy of factors is shown to be at work, including (a) nanoscopic size; (b) elevated intracellular free calcium levels due to nanoparticle solubility; (c) diffusivity and favorable electrostatic properties of the nanoparticle surface, primarily low net charge and high charge density; and (d) the dynamics of perpetual exchange of ultrafine clusters across the particle/solution interface. On the positive side, this multifaceted mechanism is less prone to induce bacterial resistance to the therapy and can be a gateway to the sphere of personalized medicine. On a more problematic side, it implies a less intense effect compared to single-target molecular therapies and a difficulty of elucidating the exact mechanisms of action, while also making the rational design of theirs for this type of medical application a challenge.

Effectiveness of casein phosphopeptide-amorphous calcium phosphate-containing products in the prevention and treatment of white spot lesions in orthodontic patients: A systematic review

The purpose of the present systematic review was to evaluate the effectiveness of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-containing products in the prevention and treatment of active white spot lesions (WSL) in orthodontic patients. Searched the Scopus, PubMed, Web of Science, Cochrane, Virtual Health Language, ClinicalTrials, and Open Gray databases without limitations on the year or language of publication. We included controlled clinical trials with patients with fixed orthodontic appliances under the use of CPP-ACP-containing products compared to control, placebo, or other interventions in the prevention and treatment of WSL around orthodontic braces. Case reports, editorials, in vitro studies, annals of congress, and reviews were excluded. To assess the risk of bias, the revised version of the Cochrane tool for randomized trials (RoB 2.0) and Risk Of Bias In Non-randomized Studies for non-randomized trials were used. The biases were graded low, moderate, and high according to the tools used. Of the 599 articles found, 11 met the inclusion criteria. Of these, nine were randomized, controlled clinical trials and two were non-randomized. Two studies were considered to have moderate bias risk, and the most-used CPP-ACP presented form was a cream for topical applications. Although CPP-ACP-containing products did not differ from other fluoride products, they were able to reduce WSL and neutralize the pH around the orthodontic braces. Products containing CPP-ACP are effective in preventing and treating WSL around the braces. However, further studies with the same measurement method and periods of use, and other forms of presentation of CPP-ACP are needed.

Nanoparticles and the control of oral biofilms

Nanoparticles, novel in size, shape, and surface chemistry when compared to more conventional materials, offer additional functional properties to a range of possible oral applications, from drug-delivery systems to dental implant coatings. Exploitation of the toxic properties of nanoparticles to bacteria, viruses, and fungi has increased markedly over recent years. Metal and metal oxide nanoparticles and their incorporation into other materials have been of particular interest. The potential of nanoparticles to control the formation of biofilms within the oral cavity, as a function of their antimicrobial, anti-adhesive, and delivery capabilities, is coming under close scrutiny. However, optimum formulation of materials at the nanoscale does require innovative physical and chemical approaches.

Biomimetic Mineralizing Agents Recover the Micro Tensile Bond Strength of Demineralized Dentin

Biomimetic remineralization is an approach that mimics natural biomineralization, and improves adhesive procedures. The aim of this paper was to investigate the influence of Dentin Caries-like Lesions (DCLL)-Producing Model on microtensile bond strength (μTBS) of etch and rinse adhesive systems and investigate the effect of remineralizing agents such as Sodium Fluoride (NaF), MI Paste™ (MP) and Curodont™ Repair (CR) on caries-affected dentin (n = 6). Nine groups were established: (1) Sound dentin; (2) Demineralized dentin/Chemical DCLL: (3) Demineralized dentin/Biological DCLL; (4) Chemical/DCLL + NaF; (5) Chemical/DCLL + MP; (6) Chemical/DCLL + CR; (7) Biological/DCLL + NaF; (8) Biological/DCLL + MP; (9) Biological/DCLL + CR. Then all dentin blocks were subjected to a bonding procedure with Adper™ Single Bond 2 adhesive system/Filtek Z350XT 4 mm high block, following this they were immersed in deionized water/24 h and then sectioned with ≅1 mm² beams. The μTBS test was conducted at 1 mm/min/500 N loading. Failure sites were evaluated by SEM (scanning electron microscopy (150×). μTBS data were submitted to factorial ANOVA and Tukey’s test (p < 0.05). The highest values were found when demineralized dentin was treated with MP and CR, regardless caries lesion depth (p < 0.05). There was a predominance of adhesive/mixed in the present study. It was concluded that the use of the artificial dentin caries production models produces differences in the μTBS. Additionally MP and CR remineralizing agents could enhance adhesive procedures even at different models of caries lesion.

In vitro Comparison of Antimicrobial Activity of Conventional Fluoride Varnishes Containing Xylitol and Casein Phosphopeptide-Amorphous Calcium Phosphate

Objective

Different fluoride varnishes are used for the prevention of dental caries. The aim of this study was to compare the antimicrobial effect of different fluoride varnishes, containing xylitol and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), on Streptococcus mutans.

Materials and Methods

In this in vitro study, the antibacterial effects of four varnishes, namely Polimo and V-varnish (containing xylitol), MI varnish (containing CPP-ACP), and Preventa, were evaluated against S. mutans. The disc diffusion method was used for testing the bacterial sensitivity. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U-tests.

Results

According to the results, Polimo showed the highest antibacterial effects, compared to the other three varnishes (P ≤ 0.05). Growth inhibition zones were not observed in V-varnish and Preventa. The mean diameter of inhibition zone around the MI varnish was significantly higher, compared to those of the V varnish and Preventa (P ≤ 0.05).

Conclusion

As the findings indicated, the fluoride varnish containing xylitol and CPP-ACP could be more effective iAQ1n the prevention of dental caries.

Coupling xylitol with remineralizing agents improves tooth protection against demineralization but reduces antibiofilm effect

To explore the efficiency of xylitol chewing gum enriched or not with remineralizing agents to protect tooth against cariogenic biofilm formation and demineralization. Six groups of chewing gums were prepared; Group 1: isomalt (1.8%), Group 2: casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (3%) + isomalt (1.8%), Group 3: hydroxyapatite (HAP) (2.5%) + isomalt (1.8%), Group 4: xylitol (1.8%), Group 5: CPP-ACP (3%) + xylitol (1.8%) and Group 6: HAP (2.5%) + xylitol (1.8%). The antibiofilm properties of different chewing gum extracts using seven oral bacterial species including Streptococcus mutans, Streptococcus constellatus, Streptococcus Salivarius and Streptococcus oralis were explored via the crystal violet staining assay. The remineralizing effects of those products were assessed on thirty human permanent teeth, half-protected with varnish before chemical erosion and thermocycling process with chewing gum. Remineralization was evaluated using scanning electron microscopy and microscopic measurements on polarized light microscopy. The ratio R comparing the thickness between unvarnished and varnished sides was evaluated. While the minimum biofilm inhibitory concentration (MBIC₅₀) was low for xylitol alone compared to isomalt, it was inconsistent when enriched with remineralizing agents. The minimum biofilm eradication concentration (MBEC₅₀) was low for xylitol groups compared to isomalt, for all the studied strains. R was significantly lower in Group 1 and Group 2, while Group 6 showed the highest ratio. Xylitol chewing gums confirmed good antibiofilm properties and showed remineralized potential on eroded teeth. When xylitol is associated to CPP-ACP or HAP, antibiofilm activity decreased while remineralization of eroded teeth increased.

Influence of biofilm formation on the mechanical properties of enamel after treatment with CPP-ACP crème

The study aimed to investigate the effects of bacterial biofilms on changes in the surface microhardness of enamel treated with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) with and without fluoride. Human enamel blocks with incipient caries-like lesions were divided into four groups of 13: G1: Saliva (Control); G2: fluoride dentifrice (Crest™, 1100 ppm as NaF); G3: CPP-ACP (MI Paste; Recaldent™); and G4: CPP-ACPF (MI Paste Plus; Recaldent™ 900 ppm as NaF). The specimens were soaked in demineralizing solution for 6 h and remineralized in artificial saliva for 18 h alternately for 10 days. The dentifrice was prepared with deionized water in a 1 : 3 ratio (w/w) or applied undiluted in the case of the CPP-ACP group. The surface microhardness (SMH) was evaluated at baseline, after artificial caries, after pH cycling and treatment with dentifrices, and after incubation in media with Streptococcus mutans for biofilm formation. The biofilms were exposed once a day to 2% sucrose and the biofilm viability was measured by MTT reduction. The percentage of change in surface microhardness (%SMHC) was calculated for each block. The data were analyzed by nonparametric test comparisons (α = 0.05). The %SMHC values observed in G2 were different from those of G1, G3, and G4 (p < 0.05). After biofilm formation, %SMHC was positive in G2 and G4 when compared to G1 and G3, but resistance to demineralization after biofilm formation was similar in all groups. In conclusion, the presence of biofilms did not influence the treatment outcomes of anticaries products.

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.

Non-conventional therapeutics for oral infections

As our knowledge of host-microbial interactions within the oral cavity increases, future treatments are likely to be more targeted. For example, efforts to target a single species or key virulence factors that they produce, while maintaining the natural balance of the resident oral microbiota that acts to modulate the host immune response would be an advantage. Targeted approaches may be directed at the black-pigmented anaerobes, Porphyromonas gingivalis and Prevotella intermedia, associated with periodontitis. Such pigments provide an opportunity for targeted phototherapy with high-intensity monochromatic light. Functional inhibition approaches, including the use of enzyme inhibitors, are also being explored to control periodontitis. More general disruption of dental plaque through the use of enzymes and detergents, alone and in combination, shows much promise. The use of probiotics and prebiotics to improve gastrointestinal health has now led to an interest in using these approaches to control oral disease. More recently the potential of antimicrobial peptides and nanotechnology, through the application of nanoparticles with biocidal, anti-adhesive and delivery capabilities, has been explored. The aim of this review is to consider the current status as regards non-conventional treatment approaches for oral infections with particular emphasis on the plaque-related diseases.

Monitoring Demineralization and Subsequent Remineralization of Human Teeth at the Dentin-Enamel Junction with Atomic Force Microscopy

Using atomic force microscopy, we monitored the nanoscale surface morphology of human teeth at the dentin-enamel junction after performing successive demineralization steps with an acidic soft drink. Subsequently, we studied the remineralization process with a paste containing calcium and phosphate ions. Repeated atomic force microscopy imaging of the same sample areas on the sample allowed us to draw detailed conclusions regarding the specific mechanism of the demineralization process and the subsequent remineralization process. The about 1-μm-deep grooves that are caused by the demineralization process were preferentially filled with deposited nanoparticles, leading to smoother enamel and dentine surfaces after 90 min exposure to the remineralizing agent. The deposited material is found to homogeneously cover the enamel and dentine surfaces in the same manner. The temporal evolution of the surface roughness indicates that the remineralization caused by the repair paste proceeds in two distinct successive phases.

Interproximal enamel reduction: an in vivo study

The study aimed to investigate the morphology and composition of the interproximal reduced enamel after exposition to saliva and casein phosphopeptide amorphous calcium phosphate with sodium fluoride (CPP-ACPF). Fourteen patients undergoing an orthodontic treatment with 4 premolars extractions participated to the study. Interproximal enamel reduction (IER) was performed on mesial surfaces of 3 extractive premolars for each patient while 1 served as untreated control. Premolars were assigned to 4 groups: No-S group, sound enamel as control; S-Ex group, stripped and immediately extracted enamel; S-Sal group, stripped and exposed to saliva enamel; S-CPP group, stripped enamel treated with CPP-ACPF. Teeth were extracted at different times, depending on the group they were assigned to and sliced into mesial and distal halves. Mesial surfaces were subjected to environmental scanning electron microscopy with energy dispersive X-ray spectrometry (ESEM/EDX) and to scanning electron microscopy (SEM) analysis. ESEM/EDX investigations showed no statistically significant differences in the content of calcium and phosphate between the 4 groups. SEM observations showed no difference in the morphological appearance of stripped enamel after 30 days of exposure to saliva and CPP-ACPF. Saliva and CPP-ACPF effects on stripped enamel in vivo showed no difference after 30 days.

Effect of CPP/ACP on initial bioadhesion to enamel and dentin in situ

The present in situ study investigated the influence of a preparation containing CPP/ACP (caseinphosphopeptide-amorphous calcium phosphate) (GC Tooth mousse) on initial bacterial colonization of enamel and dentin. Therefore, pellicle formation was performed in situ on bovine enamel and dentin specimens fixed to individual upper jaw splints worn by 8 subjects. After 1 min of pellicle formation GC Tooth mousse was used according to manufacturer's recommendations. Rinses with chlorhexidine served as positive controls. Specimens carried without any rinse served as negative controls. After 8 h overnight exposure of the splints, bacterial colonization was quantified by fluorescence microscopy (DAPI and BacLight live/dead staining). Additionally, the colony forming units (CFU) were determined after desorption. Furthermore, the effects on Streptococcus mutans bacteria were tested in vitro (BacLight). There was no significant impact of CPP/ACP on initial bacterial colonization proved with DAPI and BacLight. Determination of CFU showed statistical significance for CPP/ACP to reduce bacterial adherence on enamel. The in vitro investigation indicated no antimicrobial effects for CPP/ACP on Streptococcus mutans suspension. Under the chosen conditions, CPP/ACP (GC Tooth mousse) had no significant impact on initial biofilm formation on dental hard tissues. The tested preparation cannot be recommended for biofilm management.

Biosynthesis and Antimicrobial Activity of Semiconductor Nanoparticles against Oral Pathogens

Dental care is an essential phenomenon in human health. Oral pathogens can cause severe break which may show the way to serious issues in human disease like blood circulation and coronary disease. In the current study, we demonstrated the synthesis and antimicrobial activity of cadmium sulphide and zinc sulphide nanoparticles against oral pathogens. The process for the synthesis of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles is fast, novel, and ecofriendly. Formation of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles was confirmed by surface plasmon spectra using UV-Vis spectrophotometer. The morphology of crystalline phase of nanoparticles was determined from transmission electron microscopy (TEM) and X-ray diffraction (XRD) spectra. The average size of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles was in the range of 10 nm to 25 nm and 65 nm, respectively, and the observed morphology was spherical. The results indicated that the proteins, which contain amine groups, played a reducing and controlling responsibility during the formation of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles in the colloidal solution. The antimicrobial activity was assessed against oral pathogens such as Streptococcus sp. Staphylococcus sp. Lactobacillus sp., and Candida albicans and these results confirmed that the sulphide nanoparticles are exhibiting good bactericidal activity.

Nanoparticles and the control of oral infections

The potential of antimicrobial nanoparticles to control oral infections is reviewed. Such particles can be classified as having a size no greater than 100 nm and are produced using traditional or more novel techniques. Exploitation of the toxic properties of nanoparticles to bacteria, fungi and viruses, in particular metals and metal oxides, as well as their incorporation into polymeric materials have increased markedly over the past decade. The potential of nanoparticles to control the formation of biofilms within the oral cavity, as a function of their biocidal, anti-adhesive and delivery capabilities, is now receiving close attention. Latest insights into the application of nanoparticles within this field, including their use in photodynamic therapy, will be reviewed. Possible approaches to alter biocompatibility and desired function will also be covered.

A randomised study to compare salivary pH, calcium, phosphate and calculus formation after using anticavity dentifrices containing Recaldent(®) and functionalized tri-calcium phosphate

Aims:

The aim of this study was to estimate the pH of saliva, concentration of calcium and inorganic phosphate, and calculus formation before and after usage of Recaldent^® (GC Tooth Mousse Plus™), Functionalized Tricalcium Phosphate (3M ESPE ClinPro™ Tooth Crème) and standard dentifrice (Colgate dental cream).

Settings and Design:

Randomized double-blind study.

Materials and Methods:

A total of 50 subjects were recruited, the subjects were assessed at their first visit, on the 21^st day and on the 42^nd day. At the first visit, scaling was carried out and oral hygiene instructions were given. After 21 days, the subjects were given coded dentifrices where the operator and the subjects both were unaware of the type of dentifrice. Clinical parameters assessed were Plaque index, Gingival index, and Calculus index. Salivary samples were obtained to measure calcium, phosphate levels, and pH at 21^st day and 42^nd day.

Statistical Analysis:

ANOVA test, t-test, Mann–Whitney test, Kruskal–Wallis test.

Results:

The mean salivary calcium level and mean salivary phosphate level were higher in Group III (functionalized tricalcium phosphate (3M ESPE ClinPro™ Tooth Creme) as compared to Group II (Recaldent^® GC Tooth Mousse Plus™) and Group I (Colgate dental cream) on the 42^nd day after using dentifrices, which was statistically significant. This showed that the usage of remineralizing dentifrices led to an increase in the salivary calcium, phosphate, and pH but it did not reach the level of super saturation of the ions caused by elevated pH which could lead to calculus formation.

Conclusions:

Thought here was a statistically significant increase in salivary calcium and phosphate level in all three groups from baseline to 42^nd day, there was no calculus formation.

Effects of procedures of remineralization around orthodontics bracket bonded by self-etching primer on its shear bond strength

AIM

To evaluate the effect of the application of either fluoride varnish (FV) or amorphous calcium phosphate (ACP) as preventive method on shear bond strength (SBS) at the same time of their bonding in vitro using self-etching primer (SEP) as an agent for enamel pre-treatment FV.

MATERIALS AND METHODS

SIXTY HUMAN BICUSPIDS WERE RANDOMLY DIVIDED INTO FIVE GROUPS: G1 was rubbed by SEP for 5 s, G2 for 5 s by SEP and ACP, G3 for 10 s by SEP and ACP, G4 for 5 s by SEP and FV, and G5 for 10 s by SEP and FV. Stainless steel metal brackets were bonded. A Zwick/Roell Z020 Universal Testing Machine (Zwick GmbH and Co, Germany) with a 500 N load cell was used to test SBS. SBS values were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc tests (P≤0.05). Differences in adhesive remnant index (ARI) values between groups were calculated.

RESULTS

The mean SBS values were 10.00±4.48 MPa, 5.71±4.3 MPa, 7.47±4.44 MPa, 4.4±2.39 MPa, and 3.98±0.83 MPa for groups 1-5, respectively. Significant differences in SBS values between all groups were found. The mean SBS values of groups 2, 4, and 5 were significantly lower than that of the G1. No significant difference was found between G3 and G1. Significant difference in ARI between the groups was found (P<0.001) and G1 had a significantly higher ARI.

CONCLUSION

The results suggested that the application of ACP at the same time of using SEP for 10 s has no effect on SBS.

Biofunctional properties of caseinophosphopeptides in the oral cavity

Caseinophosphopeptides (CPPs), bioactive peptides released from caseins, have the ability to enhance bivalent mineral solubility. This is relevant to numerous biological functions in the oral cavity (promotion of tooth enamel remineralisation, prevention of demineralisation and buffering of plaque pH). Therefore, CPPs may play a positive role as prophylactic agents for caries, enamel erosion and regression of white spot lesions. Most in vitro and in situ studies demonstrate strong evidence for the bioactivity of CPPs in the oral cavity. Nevertheless, relatively little is known concerning their use as adjuvants for oral health and more particularly regarding their long-term effects on oral health.

The Use of Antimicrobial Nanoparticles to Control Oral Infections

The potential of antimicrobial nanoparticles to control oral infections is reviewed. Such particles can be classified as having a size no greater than 100 nm and are produced using traditional or more novel techniques. Exploitation of the toxic properties of nanoparticles to bacteria, fungi and viruses, in particular metals and metal oxides, and their incorporation into polymeric materials have increased markedly over the past decade. The potential of nanoparticles to control the formation of biofilms within the oral cavity, as a function of their biocidal, anti-adhesive and delivery capabilities, is now receiving close attention. The latest insights into the application of nanoparticles within this field, including their use in photodynamic therapy, will be discussed. Possible approaches to alter biocompatibility and desired function will also be covered.

Effects of casein phosphopeptide amorphous calcium fluoride phosphate paste on white spot lesions and dental plaque after orthodontic treatment: a 3-month follow-up

The effects of casein phosphopeptide amorphous calcium fluoride phosphate (CPP-ACFP) paste vs. control paste on the remineralization of white spot caries lesions and on plaque composition were tested in a double-blind prospective randomized clinical trial. Fifty-four orthodontic patients, with multiple white spot lesions observed upon the removal of fixed appliances, were followed up for 3 months. Subjects were included and randomly assigned to either CPP-ACFP paste or control paste, for use supplementary to their normal oral hygiene. Caries regression was assessed on quantitative light-induced fluorescence (QLF) images captured directly after debonding and 6 and 12 wk thereafter. The total counts and proportions of aciduric bacteria, Streptococcus mutans, and Lactobacillus spp. were measured in plaque samples obtained just before debonding, and 6 and 12 wk afterwards. A significant decrease in fluorescence loss was found with respect to baseline for both groups and no difference was found between groups. The size of the lesion area did not change significantly over time or between the groups. The percentages of aciduric bacteria and of S. mutans decreased from 47.4 to 38.1% and from 9.6 to 6.6%, respectively. No differences were found between groups. We observed no clinical advantage for use of the CPP-ACFP paste supplementary to normal oral hygiene over the time span of 12 wk.

The use of nanoparticles to control oral biofilm formation

Nanoparticles are normally considered to be of a size no greater than 100 nm, and the exploitation of their unique attributes to combat infection has increased markedly over the past decade. The potential of nanoparticles to control the formation of biofilms within the oral cavity, as a function of their biocidal, anti-adhesive, and delivery capabilities, is now coming under close scrutiny. Possible uses as constituents of prosthetic device coatings, as topically applied agents, and within dental materials are being explored. The latest insights into the application of nanoparticles in the control of oral infections, including their use in photodynamic therapy, will be discussed in this review. In particular, the use of nanoparticulate silver, copper, zinc, silicon, and their oxides will be considered in relation to their effects on bacterial populations. The recent interest in the applications of nanoparticulate polymers and calcium phosphates will also be assessed. Particular attention will be paid to the toxicity issues surrounding the potential impact of nanoparticles on oral and other tissues.

Nanomaterials in preventive dentistry

The prevention of tooth decay and the treatment of lesions and cavities are ongoing challenges in dentistry. In recent years, biomimetic approaches have been used to develop nanomaterials for inclusion in a variety of oral health-care products. Examples include liquids and pastes that contain nano-apatites for biofilm management at the tooth surface, and products that contain nanomaterials for the remineralization of early submicrometre-sized enamel lesions. However, the treatment of larger visible cavities with nanomaterials is still at the research stage. Here, we review progress in the development of nanomaterials for different applications in preventive dentistry and research, including clinical trials.