Influence of Calcium Phosphate and Apatite Containing Products on Enamel Erosion

Efficacy of peptide-based enamel coatings in the prevention of demineralization using fixed orthodontic brackets in a rat model

INTRODUCTION

White spot lesions (WSLs) represent a prominent pathology encountered during orthodontic treatment, originating from enamel demineralization induced by the accumulation of bacterial biofilms. The previously developed bioinspired enamel coating form of self-assembling antimicrobial peptide D-GL13K exhibited antimicrobial activity and enhanced acid impermeability, offering a potential solution to prevent demineralization. The primary aim of this investigation is to assess the in vivo anti-demineralization properties and biocompatibility of the D-GL13K coating.

METHODS

A rat model was developed to assess the antimicrobial enamel coating during fixed orthodontic treatment. The anti-demineralization efficacy attributed to the D-GL13K coating was evaluated by employing optical coherence tomography, Vickers microhardness testing, and scanning electron microscopy. The biocompatibility of the D-GL13K coating was investigated through histologic observations of vital organs and tissues using hematoxylin and eosin.

RESULTS

The D-GL13K coating demonstrated significant anti-demineralization effects, evidenced by reduced demineralization depth analyzed through optical coherence tomography and enhanced Vickers hardness than in the noncoated control group, showcasing the coating's potential to protect teeth from WSLs. Scanning electron microscopy analysis further elucidated the diminished enamel damage observed in the group treated with D-GL13K. Importantly, histologic examination of vital organs and tissues using hematoxylin and eosin staining revealed no overt disparities between the D-GL13K coated group and the noncoated control group.

CONCLUSIONS

The D-GL13K enamel coating demonstrated promising anti-demineralization and biocompatibility properties in a rat model, thereby suggesting its potential for averting WSLs after orthodontic interventions. Further research in human clinical settings is needed to evaluate the coating's long-term efficacy.

The composition of the dental pellicle: an updated literature review

Background

The dental pellicle is a thin layer of up to several hundred nm in thickness, covering the tooth surface. It is known to protect the teeth from acid attacks through its selective permeability and it is involved in the remineralization process of the teeth. It functions also as binding site and source of nutrients for bacteria and conditioning biofilm (foundation) for dental plaque formation.

Methods

For this updated literature review, the PubMed database was searched for the dental pellicle and its composition.

Results

The dental pellicle has been analyzed in the past years with various state-of-the art analytic techniques such as high-resolution microscopic techniques (e.g., scanning electron microscopy, atomic force microscopy), spectrophotometry, mass spectrometry, affinity chromatography, enzyme-linked immunosorbent assays (ELISA), and blotting-techniques (e.g., western blot). It consists of several different amino acids, proteins, and proteolytic protein fragments. Some studies also investigated other compounds of the pellicle, mainly fatty acids, and carbohydrates.

Conclusions

The dental pellicle is composed mainly of different proteins, but also fatty acids, and carbohydrates. Analysis with state-of-the-art analytical techniques have uncovered mainly acidic proline-rich proteins, amylase, cystatin, immunoglobulins, lysozyme, and mucins as main proteins of the dental pellicle. The pellicle has protective properties for the teeth. Further research is necessary to gain more knowledge about the role of the pellicle in the tooth remineralization process.

Biomimetic Action of Zinc Hydroxyapatite on Remineralization of Enamel and Dentin: A Review

Biomimetic zinc-carbonate hydroxyapatite technology was developed to realize materials that mimic the natural hydroxyapatite of enamel and dentin and possess good activity in terms of affinity to adhere to these biological tissues. The chemical and physical characteristics of this active ingredient allows the hydroxyapatite itself to be particularly similar to dental hydroxyapatite, enhancing the bond between biomimetic hydroxyapatite and dental hydroxyapatite. The aim of this review is to assess the efficacy of this technology in terms of benefits for enamel and dentin and reduction of dental hypersensitivity.

MATERIALS AND METHODS

A literature search (Pubmed/MEDLINE and Scopus) of articles from 2003 to 2023 was conducted to analyze studies focused on the use of zinc-hydroxyapatite products. Duplicates were eliminated from the 5065 articles found, leaving 2076 articles. Of these, 30 articles were analyzed based on the use of products with zinc-carbonate hydroxyapatite in these studies.

RESULTS

30 articles were included. Most of the studies showed benefits in terms of remineralization and prevention of enamel demineralization in terms of occlusion of the dentinal tubules and reduction of dentinal hypersensitivity.

CONCLUSION

Oral care products such as toothpaste and mouthwash with biomimetic zinc-carbonate hydroxyapatite were shown to provide benefits according to the aims of this review.

Direct and indirect effects of different dentifrices on the initial bacterial colonization of enamel in situ overnight

OBJECTIVE

The aim of this study was to investigate the direct and indirect influence of fluoridated toothpastes and fluoride-free toothpaste with hydroxyapatite (HAP) as active ingredient on initial bacterial colonization on enamel in situ.

METHODS

For this clinical-experimental pilot study, eight subjects were instructed to brush their teeth with three different toothpastes (Elmex^® : 1400 ppm AmF, Meridol^® : 1400 ppm AmF +SnF2, Karex^® : HAP), using each for two consecutive days. As a control, brushing without toothpaste was performed. To evaluate bacterial colonization, subject wore splints with buccally placed bovine enamel platelets overnight. Two modes were tested. In a first pass (regimen A), the splints were inserted after toothbrushing to examine the indirect effects of the dentifrices. In order to investigate the direct effects, the specimens were brushed in situ in a second pass (regimen B). Biofilm formation was visualized and quantified using fluorescence microscopy (DAPI and BacLight) and transmission electron microscopy (TEM).

RESULTS

For brushing regimen A (indirect effect of dentifrices), no statistical differences were detected between any of the tested dentifrices or the control. Likewise, no statistically significant differences were recorded for brushing regimen B (direct effect of dentifrices). Furthermore, no differences between the different brushing techniques were determined with regard to the ultrastructure of the overnight biofilm.

CONCLUSION

Within the limitations of the present pilot study, it can be concluded that in patients with good oral hygiene, dentifrices and their chemical composition have no statistically significant effect on the initial bacterial colonization of enamel platelets in situ, irrespectively of the mode of application.

Effect of Remineralizing Agents on Shear Bond Strength of Orthodontic Brackets-In Vitro Study

Orthodontic treatment can be effective only with the proper adhesion strength of the bonded elements on the teeth. The aim of the study was to analyze the influence of different remineralization products on the brackets (Evolve Low Profile Brackets 0.022 Roth prescription (DB Orthodontics Ltd., Silsden, England) shear bond strength (SBS)). In all, 40 teeth were investigated for this study; n = 30 demineralized (immersed in 0.1% citric acid for 30 min, twice a day, for 20 consecutive days) and n = 10 immersed only in artificial saliva. After the demineralization process, remineralization agents were applied to each group (n = 10): Group I: Elmex Sensitive professional^® toothpaste (CP, Gaba GmbH, Witten, Germany) and GC MI Paste Plus^® (GC, Leuven, Belgium), Group II: Elmex Sensitive professional^® toothpaste (CP, Gaba GmbH, Germany) and GC Tooth Mousse^® (Leuven, Belgium), Group III: Elmex Sensitive professional^® toothpaste (CP, Gaba GmbH, Germany). For the teeth in control group C, Elmex Sensitive professional^® toothpaste was used. SBS tests were performed by means of an advanced materials-testing machine that generated maximum load and tensile strength values. The data obtained underwent statistical analysis (ANOVA and Tuckey test) with a statistical threshold of p < 0.05. The SBS values were higher for group II (14.20 MPa) and I (10.36 MPa) and lower for group III (4.25 MPa) and C (4.11 MPa), with statistically significant differences between groups I and II when compared with groups III and C (p < 0.05). In conclusion, GC Tooth Mousse^® and MI-Paste Plus^® have no adverse effect on brackets SBS and are recommended to be used for enamel remineralization during orthodontic treatment.

The Effects of Selected Mouthwashes on the Surface Microhardness of a Single-shade Universal Resin Composite: In Vitro Study

Aim:

To investigate the effects of selected alcohol-free mouthwashes with different formulations (zinc-hydroxyapatite, hydrogen peroxide, and sodium fluoride) on the surface microhardness of a single-shade universal resin composite.

Materials and Methods:

Forty disc-shaped specimens (8 × 2 mm) from the universal resin composite (Omnichroma®), and a nano-hybrid composite (Tetric® N-Ceram) were prepared. After polymerization, baseline surface microhardness values were recorded using Vickers microhardness tester. The samples from each material were randomly assigned to 4 groups ( n = 10) and immersed in 20 ml of the mouthwashes: Biorepair®, Listerine®, Colgate® Optic White, and distilled water (control). The samples were kept in the immersion solutions for 24 hours, and post-immersion microhardness values were recorded. Data were analyzed with one-way ANOVA and paired sample t-tests at p < .05.

Results:

Significant reduction in microhardness was observed in all resin composite groups after immersion in the mouthwashes compared to baseline values ( p < .0001). The highest microhardness reduction in Omnichroma® group was observed after immersion in Colgate® Optic White; and Tetric® N-Ceram group after immersion in Listerine® mouthwash. For both materials, the least reduction in microhardness was observed after immersion in Biorepair®. Microhardness values for Omnichroma were significantly higher than Tetric® N-Ceram ( p < .0001). However, Omnichroma exhibited a significantly greater reduction in microhardness after immersion in the tested mouthwashes.

Conclusion:

In vitro simulated use of the investigated mouthwashes negatively affected the surface microhardness of both tested resin composites. The observed effects were both mouthwash and material dependent.

Influence of hydroxyapatite nanoparticles on the formation of calcium fluoride surface layer on enamel and dentine in vitro

Topical application of different fluoride preparations is considered to be the gold standard of oral prophylaxis measures in preventive dentistry. Hydroxyapatite nanoparticles (nano-HAP) as well, have received considerable attention for dental use in the past few decades. The purpose of this in-vitro study was to analyze the interaction between nano-HAP and different fluoride preparations. In order to investigate the possibility to establish, in the presence of nano-HAP, reproducible calcium fluoride surface layers, specimens were visually examined with regard to the surface coverage's structure, morphology, homogeneity and stability. Test series based on enamel and dentine specimens, that were obtained from extracted bovine teeth, were conducted. Thereby, sodium fluoride, olaflur, elmex Fluid (10.000 ppm) and an aqueous nano-HAP solution (5%) served as test products and sterile water as reference. First, single application of nano- HAP and fluoride was tested. After 5 min of incubation in the test solution, the surface coverage was examined by scanning electron microscopy (SEM). Furthermore, samples were determined by energy dispersive X-ray spectroscopy (EDX) to identify the present elements of the surface layer, particularly fluoride. To test the calcium fluoride layer's persistence and stability, samples were exposed to the spray of a dental multifunctional syringe for 20 s using maximum pressure and maximum water supply. In the second application protocol, fluoride and nano-HAP were applied simultaneously and in the third application protocol they were used sequentially. SEM visualisation showed that the simultaneous or sequential addition of nano-HAP led to a distinct change in the surface layer's structure. Agglomerates of various sizes were formed, with obviously different morphology from the calcium fluoride globules, not covering the surface homogeneously and sprayed off with the multifunctional syringe easily. Application of pure fluoride compounds resulted in a more homogeneous calcium fluoride surface layer with higher persistence in comparison to the combination of fluoride and nano-HAP. Interaction between fluoride and nano-HAP clearly could be proved. On enamel as well as dentine surfaces, the combined application of nano-HAP and fluoride has a negative effect on the stability and persistence of the calcium fluoride surface precipitate.

Effectiveness of Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) Compared to Fluoride Products in an In-Vitro Demineralization Model

The goal of this study was to evaluate the effectiveness of the toothpaste Tooth Mousse compared to conventional fluoride-based versions in the prevention of enamel and dentin demineralization. Human enamel and dentin samples (n = 120 each) were exposed to artificial demineralization at pH 4.92. During the demineralization process, the samples in the test groups were periodically treated with Tooth Mousse (TM) containing casein-phosphopeptide -amorphous-calcium-phosphate (CPP-ACP) and Tooth Mousse Plus (TMP) containing amorphous-calcium-fluoride-phosphate (CPP-ACPF) to evaluate their protective properties. Fluoride toothpastes containing 1400 ppm amine fluoride (AmF) and 1450 ppm sodium fluoride (NaF) were applied in the positive control groups. Treatment with distilled water (group C-W) or demineralization without treatment (group C-D) served as negative controls. After the demineralization and treatment process, all samples were cut longitudinally and lesion depths were determined at six locations using polarized light microscopy. In TM/TMP groups (enamel: 80/86 µm, dentin: 153/156 µm) lesion depths were significantly smaller compared to the negative control groups C-W/C-D (enamel: 99/111 µm, dentin: 163/166 µm). However, TM and TMP compared to the positive controls AmF/NaF (enamel: 58/63 µm, dentin: 87/109 µm) showed higher lesion depths. The application of TM/TMP (89%/78%) during demineralization led to a reduced number of severe lesions compared to the negative controls C-W/C-D (100%/95%). In this study we demonstrate that Tooth Mousse is less effective regarding prevention of enamel and dentin demineralization compared to fluoride containing toothpastes.

Biomimetic hydroxyapatite and caries prevention: a systematic review and meta-analysis

Dental caries is still one of the most prevalent diseases worldwide. Research has shown that fluoride has a role in caries prevention. For many reasons there are concerns about young children using fluoride-containing oral care products. Consequently, there is a need to identify effective fluoride-free products. A large body of literature now exists on the use of biomimetic hydroxyapatite (HAP) as an active ingredient in oral care products to combat caries.

AIM

To conduct a systematic review of the clinical evidence of the effects of HAP-based fluoride-free oral care products in caries reduction and conduct a meta-analysis of available randomized clinical trials (RCTs).

METHODS

Using the PICO question "In individuals of all ages (P), do fluoride-free oral care products containing HAP as the anti-caries agent (I), compared to products with fluoride or without caries control products (C), reduce the risk of dental caries (O)?" Ovid MEDLINE (PubMed), Scopus, EMBASE, and Web of Science databases were searched using the following keywords: apatite, hydroxyapatite, caries, dental decay, dentin(e), enamel, toothpaste, dentifrice, mouthwash, gels, biofilm, (dental) plaque, ero(de, ded, sion), (de, re)mineral(ise, ized, ised, ization, isation). Reviews, tooth whitening, tooth sensitivity, and in vitro studies were excluded. PRISMA was used for the search and GRADE was used to assess quality. Clinical trials were subjected to the Cochrane Risk of Bias assessment followed by meta-analysis.

RESULTS

291 studies were retrieved; 22 were suitable for systematic review, 5 were clinical caries trials and 4 were RCTs. A meta-analysis of 3 RCTs was possible showing HAP provided 17% protection against caries. The other 17 trials had simpler proxy outcomes for anticaries effects. Some trials showed non-inferior performance of HAP products compared to those with fluoride.

CONCLUSION

There is good evidence that hydroxyapatite in oral care products in the absence of fluoride effectively reduces caries.

The in situ potential of synthetic nano-hydroxyapatite for tooth enamel repair

This study was designed to evaluate whether nano-hydroxyapatite toothpastes with or without fluoride would be more advantageous than a fluoride toothpaste in the repair of eroded enamel in situ. Twenty-one subjects participated in this single-blind, randomized, cross-over design study with three 7-day treatment phases. In each phase, the subjects wearing a palatal appliance containing five sterilized enamel specimens used either one of the two test regimens (1% nano-hydroxyapatite toothpaste and 2.25% nano-hydroxyapatite/1450 parts per million (ppm) fluoride toothpaste) or one control (1400 ppm fluoride toothpaste). Enamel specimens were extraorally demineralized (4 × 5 min/day) and were intraorally treated with the toothpastes (2 × 2 min/day). The nano-hydroxyapatite toothpaste groups exhibited significantly higher surface microhardness than did the standard fluoride toothpaste group (p < 0.05). Enamel surface hardness was increased only by nano-hydroxyapatite toothpastes after in situ treatment compared with the baseline (p < 0.05). Morphological analysis demonstrated an apatite-type crystal deposition on the eroded enamel surface produced by nano-hydroxyapatite toothpastes, while fluoride toothpaste failed to show any significant surface deposition. Chemical analysis showed a higher content of calcium and phosphorus in the enamel surface treated with nano-hydroxyapatite toothpastes compared with that in the control one (p < 0.05). It is concluded that home use of nano-hydroxyapatite containing toothpastes may have a protective effect against erosion at the enamel surface.

In Vivo Effects of a Hydroxyapatite-Based Oral Care Gel on the Calcium and Phosphorus Levels of Dental Plaque

OBJECTIVES

 Particulate hydroxyapatite (HAP; Ca5(PO4)3(OH)) is a biomimetic oral care ingredient. One mode of action in caries-susceptible individuals may be the adhesion/incorporation of HAP into dental plaque. Therefore, the aim of this in vivo study was to analyze the 3-day effects of a newly developed hydroxyapatite-based oral care gel on the calcium and phosphorus levels within the dental plaque of children.

MATERIALS AND METHODS

 This study was conducted in Kebon Padangan at Bali in Indonesia. Thirty-four children (mean age, 8.9 years; mean DMF-T [decayed, missing, and filled teeth; permanent teeth], 0.6; mean dmft-t [primary teeth] 4.5) were included in the study. The gel was applied thrice for 3 days by an experienced dentist. Dental plaque was collected at baseline and after the study. Levels of calcium and phosphorus of plaque samples were analyzed by energy-dispersive X-ray spectroscopy.

STATISTICAL ANALYSIS

 Medians for both calcium and phosphorus levels were calculated (baseline and 3-day application of HAP-gel).

RESULTS

 The calcium level increased after 3 days of application of the HAP-gel from 0.25 wt% (median) to 0.40 wt% (median), while the phosphorus level increased from 1.17 wt% (median) to 1.41 wt% (median). However, variations in both calcium and phosphorus levels measured in the pooled dental plaque samples were high.

CONCLUSION

 Within the limitations of the study, the 3-day application of the oral HAP-gel in children increased the median of both calcium and phosphorus levels in plaque. Consequently, a positive influence on the remineralization/demineralization process is very likely.

Biomimetic Effect of Nano-Hydroxyapatite in Demineralized Enamel before Orthodontic Bonding of Brackets and Attachments: Visual, Adhesion Strength, and Hardness in In Vitro Tests

Dietary habits with high consumption of acidic food can induce in orthodontic patients an increased risk of demineralization lesions around orthodontic brackets and bands. The purpose of the present laboratory study is to assess the in vitro visual efficacy of a biomimetic nano-hydroxyapatite remineralizing solution in a hypomineralized enamel surface and its effect on adhesion of fixed orthodontic appliances and on enamel microhardness. Intact teeth were demineralized, and subsequently the areas of demineralization were visually recorded using a 0-100 scale. Subsequently, a remineralizing solution (Biorepair® Repair Shock Treatment) was applied for ten minutes once a day/for one week per month for a total remineralizing treatment of 3 months. Visual effects were recorded. Moreover, bond strength was recorded and adhesive remnant index scores were measured for both orthodontic brackets and composite attachments both before demineralization and after demineralization and application of remineralizing solution. Also, Vickers microhardness was measured. All data were submitted to statistical analysis. The application of remineralizing solution induced a significant in vitro reduction of demineralized areas after the first week of application. No significant differences between untreated enamel surfaces and remineralized surfaces were detected after 2 months of remineralizing treatment. Bond strength values were significantly reduced for both brackets and attachments after remineralizing treatment. However, attachments showed higher adhesion values than brackets in both conditions tested. Remineralized enamel showed significantly higher microhardness values than demineralized enamel and lower values than intact enamel.

Adhesion of Hydroxyapatite Nanoparticles to Dental Materials under Oral Conditions

Hydroxyapatite nanoparticles (nano-HAP) are receiving considerable attention for dental applications, and their adhesion to enamel is well established. However, there are no reports concerning the effects of HAP on other dental materials, and most of the studies in this field are based on in vitro designs, neglecting the salivary pellicle-apatite interactions. Thus, this in situ pilot study aims to evaluate the effects of three hydroxyapatite-based solutions and their interactions with different dental material surfaces under oral conditions. Hence, two volunteers carried intraoral splints with mounted samples from enamel and from three dental materials: titanium, ceramics, and polymethyl-methacrylate (PMMA). Three HAP watery solutions (5%) were prepared with different shapes and sizes of nano-HAP (HAP I, HAP II, HAP III). After 3 min of pellicle formation, 10 ml rinse was performed during 30 sec. Rinsing with water served as control. Samples were accessed immediately after rinsing, 30 min and 2 h after rinsing. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the particles, and SEM evaluated the pellicle-HAP interactions. SEM and TEM results showed a high variation in the size range of the particles applied. A heterogeneous HAP layer was present after 2 h on enamel, titanium, ceramics, and PMMA surfaces under oral conditions. Bridge-like structures were visible between the nano-HAP and the pellicle formed on enamel, titanium, and PMMA surfaces. In conclusion, nano-HAP can adhere not only to enamel but also to artificial dental surfaces under oral conditions. The experiment showed that the acquired pellicle act as a bridge between the nano-HAP and the materials' surface.

Characterization of the in situ pellicle ultrastructure formed under the influence of bovine milk and milk protein isolates

OBJECTIVES

The present study aimed to investigate if bovine milk or milk protein isolates, respectively, alter the ultrastructure of thein situ pellicle and might therefore have an influence on oral health.

METHODS

In situ pellicle samples were formed on bovine enamel slabs exposed in the oral cavity of three subjects for 6, 30, 60 or 120 min. After 3 min of pellicle formation, mouthrinses were performed for 3 min with (non-)homogenized UHT- or fresh milk (0.3% or 3.8% fat), 30% UHT-treated cream or different types of casein- or milk protein isolates containing preparations. The specimens were removed after the exposure times and transmission electron microscopy (TEM) was performed. Native pellicle samples served as controls.

RESULTS

Topical ultrastructural pellicle modifications were detected after mouthrinses with all types of homogenized UHT- or fresh milk and after the application of a 3% native casein micelles containing experimental solution. Atypical globular protein structures, identified as casein micelles, were temporarily adsorbed onto the pellicle. They were closely associated with lipid droplets. Furthermore, the mouthrinses occasionally affected the morphology of salivary bacteria. However, no notable ultrastructural alterations remained after 120 min of pellicle formation.

CONCLUSION

For the first time, bovine milk- and micellar casein-induced pellicle modifications were revealed by TEM. The adsorption of micellar casein is possibly due to its molecular interactions.

CLINICAL SIGNIFICANCE

Bovine milk or micellar caseins provide some potential for the development of preventive strategies against bacterial biofilm formation or erosive processes at the tooth surface.

Effect of fluoride mouthrinses and stannous ions on the erosion protective properties of the in situ pellicle

The particular feature of this study is the investigation of effects of pure fluoride- or stannous ions based mouthrinses on the erosion protective properties and the ultrastructure of the in situ pellicle (12 volunteers). Experimental solutions were prepared either from 500 ppm NaF, SMFP, AmF or SnF₂ or 1563 ppm SnCl₂, respectively. After 1 min of in situ pellicle formation on bovine enamel slabs, rinses with one of the preparations were performed for 1 min and intraoral specimens’ exposure was continued for 28 min. Native enamel slabs and rinses with bidestilled water served as controls. After oral exposure, slabs were incubated in HCl (pH 2; 2.3; 3) for 120 s and kinetics of calcium- and phosphate release were measured photometrically; representative samples were analysed by TEM and EDX. All mouthrinses reduced mineral loss compared to the native 30-min pellicle. The effect was pH-dependent and significant at all pH values only for the tin-containing mouthrinses. No significant differences were observed between the SnF₂- and the SnCl₂-containing solutions. TEM/EDX confirmed ultrastructural pellicle modifications. SnF₂ appears to be the most effective type of fluoride to prevent erosive enamel demineralisation. The observed effects primarily have to be attributed to the stannous ions’ content.

Effect of Cpp-aCp and Cpp-aCpf pastes on the Surface Hardness of Initial Dental Erosion Lesions: an In Situ Study

To analyze the effect of intra-oral application of CPP-ACP and CPP-ACPF pastes on the surface hardness of initial dental erosion lesions.Bovine enamel specimens were randomly assigned into 6 volunteers in 3 treatment groups: GI: CPP-ACP paste, GII: CPP-ACPF paste and GIII (Control): Placebo paste without CPP-ACP and without fluoride. Enamel specimens were selected by surface hardness (SHi), in vitro eroded by immersion in hydrochloric acid for 30 seconds (SHdes) and randomized between treatment groups and volunteers, who used the palatal intraoral device for 2 hours, applied the treatment on the specimens and used the palatal intraoral device for an additional 3 hours in 3 crossed phases, interspersed with a 7-day washout period. Subsequently, the surface hardness (SHre) was measured to estimate the re-hardening potential of the softened enamel promoted by treatments. Data were analyzed using the t-test and one-way ANOVA, adopting 5% significance level. Mean final and post-erosion hardness values were statistically significant for pastes tested (p<0.05), which presented re-hardening effect of the softened enamel, but with no difference between them and placebo (p>0.05). CPP-ACP and CPP-ACPF pastes did not demonstrate higher efficacy in re-hardening the eroded enamel compared to placebo paste.

Overview of Calcium Phosphates used in Biomimetic Oral Care

Background:

The use of biomimetic agents is an emerging field in modern oral care. Promising biomimetic substances for such applications are calcium phosphates, because their chemical composition is very similar to that of the mineral phase in human teeth, especially of natural enamel. Examples for their application include the remineralization of early caries lesions and repair of small enamel defects.

Objective:

This review provides an interdisciplinary view on calcium phosphates and their applications in biomimetic oral care. The aim of this work is to give an overview of in vivo and in situ studies comparing several calcium phosphates in preventive dentistry that can be used as a knowledge base for the development of innovative alternative oral care concepts.

Methods:

Books, reviews, and original research papers with a focus on in vivo and in situ studies were included. The databases PubMed^® and SciFinder^® were used for literature search. Calcium phosphates that are frequently utilized in oral care products are covered in this review and were used as search terms alone and together with the following key words: in vivo, in situ, caries, clinical study, and remineralization. From 13,470 studies found, 35 studies complied with the inclusion criteria and were used for this review.

Results:

Published in vivo and in situ studies demonstrate calcium phosphates’ potential in enamel remineralization. However, more studies are needed to further substantiate existing results and to extend and refine the application of calcium phosphates in modern oral care.

Conclusion:

Calcium phosphates represent an innovative biomimetic approach for daily oral care because of their high similarity to natural enamel that will broaden the range of future treatments in preventive dentistry.

In situ effect of Tooth Mousse containing CPP-ACP on human enamel subjected to in vivo acid attacks

OBJECTIVE

This in situ study aimed to evaluate the protective effect of Tooth Mousse (GC) containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on human enamel erosion and to compare the difference in erosion between the anteriorly and posteriorly positioned human enamel.

METHODS

This study used a 2-treatment (7 days each) crossover design with 12 healthy volunteers wearing intraoral appliances. Each appliance contained 4 human enamel specimens positioned on the buccal surfaces of the volunteers' maxillary central incisors and first molars. The specimens were intraorally treated withTooth Mousse (CPP-ACP group) or deionized water (control group) for 3 min and then exposed to in vivo acid attacks by rinsing with 150 ml of a cola drink (4 × 5 min/day). The surface microhardness (SMH) of the specimens was measured and used to calculate the percentage of SMH loss (%SMH_l). Erosion effect on enamel was also investigated by scanning electron microscopy (n = 4) at the end of study. The data were statistically analysed using two-way analysis of variance (ANOVA) and Tukey's test at a level of P < 0.05.

RESULTS

A significant decrease in %SMH_l was observed for the specimens of CPP-ACP group compared to that for the controls (P = 0.007). The specimens positioned posteriorly exhibited a significantly lower %SMH_l than those positioned anteriorly (P = 0.033). Samples of CPP-ACP group showed fewer etching patterns than those of the control group.

CONCLUSIONS

In this in situ model, application of Tooth Mousse containing CPP-ACP before erosion reduced the %SMH_l of human enamel. Enamel located in different positions showed different patterns of erosion.

CLINICAL SIGNIFICANCE

Application of Tooth Mousse containing CPP-ACP could be considered as a suitable preventive strategy against enamel erosion. ClinicalTrials.gov Identifier: NCT03426150.

Impact of customary fluoride rinsing solutions on the pellicle's protective properties and bioadhesion in situ

This study investigated the impact of customary fluoride based mouthrinses on the ultrastructure and the functional properties of the in situ pellicle, considering the prevention of erosion (8 volunteers) and initial biofilm formation (12 volunteers). Bovine enamel slabs were carried intraorally. After 1 min of pellicle formation, the subjects rinsed with elmex Kariesschutz (A), Dontodent Med Care (B), meridol (C) or elmex Zahnschmelzschutz Professional (D) for 1 min. In situ pellicle formation was continued up to 30 min/8 h before processing the slabs in vitro. Erosion was simulated by incubating the specimens in HCl (pH 3.0, 2.3, 2.0) for 120 s, measuring the kinetics of calcium/phosphate release photometrically; representative samples were evaluated by TEM and EDX. Bacterial adhesion was visualized fluorescence microscopically (DAPI/BacLight). Native enamel slabs or physiological pellicle samples served as controls. All investigated mouthrinses enhanced the erosion preventive pellicle effect in dependence of the pH-value. A significant decrease of Ca/P release at all pH values was achieved after rinsing with D; TEM/EDX confirmed ultrastructural pellicle modifications. All mouthrinses tendentially reduced bacterial adherence, however not significantly. The mouthrinse containing NaF/AmF/SnCl₂ (D) offers an effective oral hygiene supplement to prevent caries and erosion.