Enamel protection of resin composite containing hydrated calcium silicate by microleakage simulation

doi:10.21203/rs.3.rs-2233044/v1

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Enamel protection of resin composite containing hydrated calcium silicate by microleakage simulation

https://doi.org/10.21203/rs.3.rs-2233044/v1

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Background. The gaps at the margins of restorative composite resin can increase as the carious process occurs underneath the materials, causing further demineralization along the tooth cavity wall. The aim of this study was to evaluate the effects of restorative resin composite containing hydrated calcium silicate (hCS) filler on enamel protection against demineralization by simulating microleakage between the test material and teeth in a cariogenic environment.

Methods. The experimental resin composites were composed of 70 wt% filler, which was mixed with a glass filler and hCS in a weight ratio of 70.0% glass (hCS 0), 17.5% hCS + 52.5% glass (hCS 17.5), 35.0% hCS + 35.0% glass (hCS 35.0), and 52.5% hCS + 17.5% glass (hCS 52.5). A light-cured experimental resin composite disk was positioned over a polished bovine enamel disk, separated by a 30-µm gap, and immersed in artificial saliva with pH 4.0 for 15, 30, and 60 days. After the immersion period, the enamel disk was separated from the resin composite disk and evaluated using a microhardness tester, atomic force microscopy, and polarized light microscopy. The opposing sides of the enamel and resin composite disks were observed using scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS).

Results. The enamel surface showed a significant increase in microhardness, decrease in roughness, and remineralization layer as the proportion of hCS increased (P < 0.05). In the SEM image, enamel surface with hCS 35.0 and 52.5 after all experimental immersion periods showed a pattern similar to that of a sound tooth.

Conclusions. The results demonstrated that increasing the hCS filler level significantly increased the prevention effect of enamel demineralization compared to restorative resin composites containing conventional dental glass filler. Despite some microleakage exposed to a cariogenic environment, these novel composites may be promising dental biomaterials for protecting teeth against demineralization and preventing secondary caries around the restorations.

Hydrated calcium silicate

Enamel surface

Demineralization

Remineralization

Surface roughness

Microhardness

Despite their long history of use and many advantages due to their esthetics, direct filling, and light-polymerization capabilities, dental resin composites have limitations with marginal or secondary caries adjacent to restorations, which may occur around the material-tooth interface following the microleakage induced by the polymerization shrinkage of the resin-based composite material [1]. Marginal or secondary caries are caused by dental plaque accumulation over and at the margins of restorative composite resin and by the release of organic acids and enzymes produced by the oral cariogenic bacteria during fermentation [2, 3]. The gaps at the margins of restorative composite resin can increase as the carious process occurs underneath the materials, causing further demineralization along the tooth cavity wall [4]. Therefore, it is necessary that dental resin composite materials provide preventive and therapeutic properties to inhibit caries risk, which can be successful in clinical application for many years.

To prevent the development of marginal or secondary caries, bioactive dental resin composites have been studied [5–7]. For example, the incorporation of bioactive glass containing calcium and phosphate components into resin-based composites inhibits tooth demineralization in a cariogenic environment [8]. As a type of bioactive material, Portland cement has been a popular choice of dental biomaterial owing to its biocompatibility and bioactive properties, which are mineral trioxide aggregates mainly composed of calcium silicate complexes [9, 10]. In addition, it has been observed that hCS (hCS) promotes an alkaline pH and releases high levels of calcium ions rather than un-hCS in aqueous environments [11]. Calcium and hydroxyl ions released from hCS can help prevent demineralization and impart acid resistivity to enamel and dentin.

However, these results only showed the neutralization effect and calcium ion release in acid solution, but were not sufficient to prove the effect on teeth to prevent demineralization together with the promotion of remineralization around restorations under simulated cariogenic challenge.

Organic acids produced by bacteria derived from human dental plaque play a critical role in the biodegradation of resin-based composites, which causes deterioration of the material surface and at the tooth-resin composite interface [12]. In a cariogenic environment, whether a resin composite containing hCS filler could prevent demineralization and enhance remineralization of teeth has not been confirmed yet. Moreover, the influence of the cariogenic environment on the micromorphology and chemical elements of resin composites containing hCS fillers has not been investigated.

Therefore, the purpose of this study was to investigate the effects of restorative resin composites containing different concentrations of hCS filler on enamel protection against demineralization by simulating microleakage between the test material and tooth in a cariogenic environment for a prolonged period of time. The null hypotheses were that 1) increasing the hCS filler content could not prevent enamel demineralization with the same immersion time in artificial saliva with pH 4.0 and 2) increasing the immersion time in artificial saliva with pH 4.0 could not prevent enamel demineralization with the same hCS filler content.

Preparation of the experimental resin composites containing an hCS filler

White Portland cement (Union White Portland cement, Gyunggido, Korea) was used in this study as a calcium silicate material. To prepare the hCS (hCS) filler, white Portland cement was mixed with distilled water in a water/powder weight ratio of 0.33 for 1 min. The mixed paste was stored at 100% relative humidity and 37 ± 1°C for 72 h. After the hCS set, hCS powder was obtained using a planetary ball mill (PM 100 CM, Retsch, Haan, Germany) at 450 rpm for 40 min. The ground hCS powder was filtered through a 400-mesh sieve and was not silanized. The D50 (median particle size) of the hCS particle as determined by a particle size analyzer (Mastersizer 2000, Malvern, Malvern, Worcestershire, UK) was 18 µm.

To create the light-curable resin matrix, 49.5 wt.% bisphenol A glycerolate dimethacrylate, 49.5 wt.% triethylene glycol dimethacrylate, 0.3 wt.% camphorquinone, and 0.6 wt.% 2-(dimethylamino)ethyl methacrylate were blended using a magnetic stirrer in the light-shielded vial for 24 h. All chemicals were purchased from Sigma-Aldrich (Steinheim, Germany).

To obtain a homogeneous experimental resin composite, the filtered hCS powder and silanized dental glass filler (NF180, 55.0 wt% SiO₂, 25.0 wt% BaO, 10.0 wt% B₂O₃, and 10.0 wt% Al₂O₃, Schott, Landshut, Germany) were mixed with the light-curable resin matrix using a magnetic stirrer in the light-shielded vial on the 50 ± 1 ℃ hot plate for one day. Experimental resin composites containing hCS fillers were then prepared in four groups (Table 1).

To make the experimental resin composite disk, a stainless steel mold with a diameter of 10.0 mm and a thickness of 1.0 mm was filled with uncured experimental resin composite and clamped between glass slides covered with polyester films. The experimental resin composite was then immediately polymerized with overlapping areas for 20 s using an LED light-curing unit (Elipar S10, 3M ESPE Co., Seefeld, Germany). The irradiation procedure was repeated on the other side. The light-cured experimental resin composite was then separated from the mold, and any flash on the specimen was removed with 400 grit silicon carbide (SiC) abrasive paper (Deerfos, Incheon, Korea).

Table 1. Filler proportions in the experimental groups (Wt.%)

Group	hCS 0	hCS 17.5	hCS 35.0	hCS 52.5
Content of resin matrix	30.0	30.0	30.0	30.0
Content of hydrated calcium silicate filler	0.0	17.5	35.0	52.5
Content of silanized dental glass filler	70.0	52.5	35.0	17.5

Preparation Of Bovine Enamel Disk

A total of 78 freshly extracted bovine incisors with no cracks, erosion, or caries were selected for this study. The crown was separated from the root using a micromotor (Strong 230, Saeshin Precision, Daegu, Korea) with a diamond-coated disk (NTI-Kahla GmbH, Kahla, Germany). The labial surface of the separated crown was ground with a water-cooled rotating polishing machine (EcoMet 30; Buehler Ltd., Lake Bluff, IL, USA) with 1200- and 2000-grit SiC abrasive paper to obtain a flat enamel surface. The lingual, mesial, and distal surfaces were ground with a water-cooled rotating polishing machine with 400-grit SiC abrasive paper to make the disk-shaped tooth specimen with 10.0 ± 0.1 mm in diameter and 2.0 ± 0.1 mm thickness. To remove any polishing residues, the enamel disk specimen was ultrasonically washed in distilled water for 10 min. Six enamel disk specimens were randomly chosen for the baseline assessment.

Simulation Of Microgap With Resin Composite And Enamel Disk

To simulate the microgap between the resin composite and the tooth structure, 2 polyester films with 1.0 mm × 10.0 mm × 30 µm were positioned on each end of the labial enamel surface and covered with an experimental resin composite disk. The assembly was entirely wrapped by Parafilm (BEMIS, Neenah, WI, USA) perpendicular to the long axis of the polyester films to avoid separation of the resin composite disk from the enamel disk while leaving both gap surfaces open. Eighteen microgap assemblies were prepared for each experimental group.

Exposure of the microgap between the resin composite and enamel disk to artificial saliva with pH 4.0

Artificial saliva with a pH of 4.0 (AS 4) was prepared by dissolving 0.245 g KH₂PO₄ and 0.4411 g CaCl₂·2H₂O in 800 mL of distilled water and added with 5.72 mL acetic acid. The pH was adjusted to 4.0, by adding 0.5 M KOH, and distilled water was then added to make up a total volume of 2.0 L. All chemicals were purchased from Sigma-Aldrich (Steinheim, Germany).

The microgap between the resin composite and enamel disk was completely filled with AS 4 using a micropipette. A microgap assembly containing AS 4 was then immersed in 10 mL of AS 4 at 37 ± 1°C in a shaking incubator (IST-4075, Lab Companion, Daejeon, Korea). The AS 4 between the resin composite and enamel disk was refreshed daily using a micropipette for 15, 30, and 60 days. Concurrently, AS 4 used for the immersion of the microgap assembly filled with AS 4 was also refreshed for 15, 30, and 60 days. After the immersion period, the resin composite and enamel disk were separated from the microgap assembly, washed in distilled water, and dried in a desiccator at 25 ± 2°C for 48 h. Then, the resin composite and enamel disk exposed to AS 4 in the microgap model were randomly examined from the edge to the center using the following methods.

Roughness Of The Enamel Surface

The roughness and topography of the enamel surface were analyzed using atomic force microscopy (AFM; NX-10, Park Systems, Suwon, Korea). The surface roughness of the enamel disk was measured at five random areas to calculate the mean value of each enamel disk in non-contact mode at a scan size of 20 µm ⋅ 20 µm at a scanning rate of 1 Hz. In addition, three-dimensional surface topography was observed using the XEI software obtained from Park Systems. Enamel disk specimens that were not attached to the resin composite disks were also measured for the baseline assessment.

Microhardness Of Enamel Surface

After assessing the surface roughness, the Vickers microhardness of the enamel surface was measured using a microhardness tester (MMT-X7B, Matsuzawa, Akita-Shi, Japan) at a 200 g load for a dwell time of 15 s. Indentations were made at five random locations to calculate the mean value of each enamel disk. Enamel disk specimens that were not attached to the resin composite disks were also measured for the baseline assessment.

Scanning Electron Microscopy/energy Dispersive X-ray Spectrometry (Sem-eds) Analysis

For the micromorphological observation, a micromotor with a diamond-coated disk was used to cut each enamel disk specimen in half. Half of the enamel disks were washed in distilled water, dried, Pt-coated, and examined using SEM (JEOL JSM-7001F, JEOL Ltd., Tokyo, Japan) under an accelerating voltage of 15.0 kV and magnification of 5000 ⋅. In addition, the resin composite disk was cross-sectioned and then polished using a water-cooled rotating polishing machine with 2000-grit SiC abrasive paper. The surface and cross section of the experimental resin composite facing the enamel surface at the microgap assembly were sputter-coated with carbon and observed using SEM-energy dispersive X-ray spectrometry (SEM-EDS; Merin, Carl Zeiss, Oberkochen, Germany) with an accelerating voltage of 15.0 kV, with magnifications ranging from 1000 to 10000 ⋅. EDS mapping observations were performed to detect the following elements: carbon, oxygen, aluminum, silicon, barium, calcium, and phosphorus. Resin composite and enamel disks that were not exposed to AS 4 were also prepared for the baseline assessment.

Polarized Light Microscopy Analysis

After observing the SEM image, another half of the enamel disk specimen in each group was sectioned in the labia-lingual direction using a low-speed diamond wheel (DAIMO-100S, MTDI, Daejeon, Korea), initially obtaining slices of 500 µm in thickness, and polished with 1200-grit SiC paper to obtain a slice of 150 µm in thickness. Immediately afterward, the slices were positioned on a glass slide and observed using an optical microscope equipped with a polarizing filter (BX41, Olympus, Tokyo, Japan) at 20 ⋅ magnification to determine the depth of discoloration.

Statistical analysis

The enamel surface roughness and microhardness values of the different groups at the same immersion time were analyzed using a one-way analysis of variance test (SPSS 25, IBM Co., Armonk, NY, USA) followed by Tukey’s statistical test (p = 0.05). The enamel surface roughness and microhardness values of the different immersion times within the same experimental group were also analyzed using the same method.

Enamel surface roughness

The surface roughness (Ra) value for enamel disks that were not attached to the experimental resin composite disks (baseline) was 14.37 ± 5.08 nm. The surface roughness of enamel with hCS 0 showed a relatively higher Ra value than the other groups containing hCS at 15, 30, and 60 days (P < 0.05) (Fig. 1a). In particular, the Ra value of the enamel surface with hCS 0 was nearly 10-fold higher than that of hCS 52.5 at 60 days. In comparison, the Ra values of the enamel surface with hCS-containing groups were significantly lower than those of hCS 0 (P < 0.05), and the hCS filler proportion had no significant effect on the Ra value (P > 0.05). The Ra values of the enamel surface increased with increasing immersion time in the AS 4 for the hCS 0 and hCS 17.5 groups (P < 0.05). However, the Ra values of the enamel surface with hCS 35.0 and hCS 52.5 showed no significant change despite increasing the immersion time in AS 4 (P > 0.05). As illustrated in Fig. 1b, the enamel with hCS 0 at different immersion times showed a relatively rougher surface with sharp and irregular patterns on the entire surface. The enamel surface with hCS 17.5 showed partially irregular peaks as the immersion time increased; however, it was weaker than that of hCS 0. In contrast, enamel surfaces with hCS 35.0 and hCS 52.5 did not show any sharp peaks, similar to the baseline surface, and showed evidence of a plain structure with a weak polish trace.

Enamel Surface Microhardness

The VHN for the enamel disk surface that was not attached to the experimental resin composite disks (baseline) was 316.35 ± 9.56. The microhardness of the enamel surface with hCS 0 showed a lower VHN than the hCS-containing groups at 15, 30, and 60 days (P < 0.05) (Fig. 1c). The VHN of the enamel surface increased as the proportion of the hCS filler increased during all immersion periods (P < 0.05). In particular, the VHN of the enamel surface with hCS 52.5 was high nearly 3-fold when compared with hCS 0 at 60 days. Decreasing the VHN values of the enamel surfaces were revealed with increasing immersion time for the hCS 0, hCS 17.5, and hCS 35.0 groups (P < 0.05). However, VHN of the enamel surface with hCS 52.5 was significantly increased with increasing the immersion time in AS 4 (P < 0.05).

Sem-eds Analysis Of Enamel And Resin Composite Disks

Typical SEM images of enamel surfaces with experimental resin composite disks at 15, 30, and 60 days of exposure to AS 4 are shown in Fig. 2. Figure 2a-c shows an enamel surface with hCS 0 after 15, 30, and 60 days of immersion, demonstrating that mineral was lost from the rod core, and only an intact interrod region remained as a “keyhole” structure. In particular, the above demineralization phenomenon of the enamel surface with the hCS 0 group became more pronounced as the immersion time increased. The enamel surface with hCS 17.5 exhibited a relatively smooth surface after 15 days and 30 days immersion compared to the enamel surface with hCS 0, whereas enamel surface after 60 days immersion showed minor mineral loss in the enamel rod sheath area (Fig. 2d-f). Figure 2g-l shows an un-demineralized enamel surface for hCS 35.0 and 52.5 after 15, 30, and 60 days of immersion, similar to the characteristic pattern of baseline, which appears to be a relatively intact surface (Fig. 2m).

The surface of the resin composite disks before and after immersion in AS 4 showed an even distribution of micro- or nano-sized fillers, and cross-sectional images showed polished traces with irregularly roughened surfaces in the hCS-containing groups (Fig. 3a, b). In addition, noticeable differences on the resin surface were not detected after immersion as compared with those before immersion. However, as the content of hCS increased, the cross-sectional images showed a slightly uneven outer surface after 60 days of immersion. As a result of the EDS analysis, Al, Si, and Ba peaks were detected at hCS 0 in both the surface and cross-section before immersion, and a uniform distribution of elements was observed in the mapping image, which was the same even after 60 days of immersion (Fig. 3c, d). In addition to Al, Si, and Ba, the Ca peak was detected on both the surface and cross-section of the resin composite disk containing hCS before immersion, and the wt.% of the detected Ca was increased as the content of hCS increased in the experimental resin composite (all data not shown). After immersion, the P peak was detected on both the surface and cross-section of the resin composite disk containing hCS. In the mapping image, it was confirmed that the distributions of Ca and P were almost identical.

Polarized Light Microscopy Analysis

Polarized light microscopy images of the tooth specimens are shown in Fig. 4. After 60 days of immersion in artificial saliva at pH 4.0, the cross-sectional images showed that discoloration was limited to the superficial surface of the sound enamel (Fig. 4a). The depth of the visible discoloration in the hCS 0 and hCS 17.5 groups was deeper than that of the sound enamel, and hCS 17.5 showed a discoloration depth with a gradual decrease in intensity towards the dentin side compared to the hCS 0 (Fig. 4b, c). hCS 35.0 and hCS 52.5 showed remineralized and demineralized zones together on the top of the cross-sectional surface (Fig. 4d, e). In particular, hCS 52.5 exhibited a thinner demineralized zone and clear remineralization layer compared to hCS 35.0.

Even though the dental resin composites are widely used owing to their excellent esthetic and mechanical properties, a marginal gap at the interface between teeth and resin composite frequently occurs, which requires replacement of the restoration. The marginal gap caused by setting shrinkage or marginal enamel cracking in restoration [13] offers space for bacteria to invade and accumulate, resulting in an acidic environment around the composite resin, which ends with secondary or recurrent caries. Therefore, the development of dental caries-against resin composites is needed.

HCS is known as acid neutralization and the release of calcium ions in aqueous environments [11]. Consequently, various studies have applied hCS as a biocompatible material for dental materials. In this study, hCS was derived from white Portland cement because its main components are dicalcium silicate and tricalcium silicate. However, there is a lack of studies on how resin composites containing hCS fillers could affect the teeth during exposure to repeated cariogenic conditions. This research is the first study to demonstrate hCS fillers in restorative resin composites, which are applied to teeth in a cariogenic environment with simulated microleakage. To simulate microleakage in the oral environment, the size of the designed microleakage in this study was 30 µm because the minimal gap between teeth and restorations for developing secondary caries was 30 µm, according to Maske et al [4]. Within this marginal gap, acidic artificial saliva was injected to mimic the demineralization environment. The tooth surfaces were then analyzed in terms of their resistance to the acidic solution.

AFM has been widely used in the surface analysis because three-dimensional images at a nanometric resolution can be obtained without any damage to the specimen surface [14]. Therefore, AFM was used in this study to evaluate the roughness of the enamel surface. The results showed that the experimental resin composites containing hCS had a lower Ra than the hCS 0. In addition, despite exposure to acidic artificial saliva for a long time, the Ra values of hCS 35.0 and hCS 52.5 were particularly similar to that of the baseline (before immersion). Enamel demineralization is caused by the loss of tooth minerals via acidic dissolution. Hydroxyapatite, the main mineral component of enamel, dissolved gradually in a low-pH environment. The physiological equilibrium in the oral cavity remains intact by cycling demineralization and remineralization. However, this balance is disrupted when excessive acid from the cariogenic bacteria hinders the ability of saliva to buffer the acidic oral environment [15]. In this manner, the lower Ra values in experimental groups containing hCS represent the possibility of hCS inhibiting demineralization and/or enhancing the remineralization of enamel.

Microhardness is related to local calcium content, which can represent comparative hardness measurements as well as direct figures of mineral loss or gain by demineralization or remineralization [16]. There is no standard condition for the enamel microhardness test. Among the various hardness tests, the Vickers hardness test is more useful than the Knoop hardness test because it can be easily detected on roughened or acid-eroded teeth [17]. The results of the microhardness test showed that VHN increased with the hCS proportion, even though the VHN of groups containing hCS was lower than the baseline. This implies that hCS has the potential to delay the dissolution of minerals in the enamel or remineralize the demineralized teeth. In addition, along with the surface roughness results, hCS prevented demineralization by showing significantly lower roughness while presenting a much higher microhardness in hCS 52.5 at all experimental periods.

The SEM results showed that hCS 0 had a rough surface owing to mineral loss from demineralization. In contrast, the surface of enamel became smoother as the content of hCS was increased, especially when the hCS 35.0 and hCS 52.5 had an intact surface similar to that of sound enamel. These results suggest that the experimental specimens containing a high proportion of hCS retained more unimpaired enamel surface in acidic surroundings compared to the hCS 0. In addition, the SEM-EDS of the cross-sectioned hCS 52.5 resin disk after immersion for 60 days presented distributed Ca ions over the surfaces with P ions as a thin layer on top. Several studies have demonstrated that calcium silicate compounds form hydroxyapatite in simulated body fluids [18, 19]. The Ca ions from the hCS form calcium phosphate compounds with P ions from artificial saliva containing phosphate. Therefore, the Ca and P detected in the experimental specimens could be calcium phosphate compounds formed during the simulated demineralizing process. These compounds replaced the space created by mineral loss, which may be considered as remineralization. As a result, the enamel surface attached to the experimental groups containing hCS, especially hCS 35.0 and hCS 52.5, showed a smooth surface similar to the baseline due to ions released from hCS.

The outcome of the polarized light microscopy provided images of discoloration depth, which could be seen as an indicator of the depth of mineral loss from the enamel and therefore of demineralization. After 60 days of storage in artificial saliva at pH 4.0, a wide range of discoloration was detected for hCS 0 and hCS 17.5. However, remineralized layers over the demineralized zone were observed from hCS 35.0 and hCS 52.5, according to the cross-sectioned images. In addition, the depth of demineralization decreased as the hCS contents increased, and hCS 52.5 had the shortest demineralization depth. Remineralization occurs when calcium and phosphate recrystallize on the surfaces of the remaining crystals in enamel or dentin [20]. From the SEM-EDS results, it was confirmed that calcium-phosphate compounds were formed from the composite resin containing hCS when immersed in artificial saliva. Therefore, the remineralized zone detected by polarized light microscopy can be explained by the EDS results that calcium ions released from hCS and phosphate ions in the artificial saliva formed apatite, which eventually remineralized the demineralized enamel. In addition, since the hCS 35.0 and hCS 52.5 specimens had remineralized surface, the microhardness values of these experimental specimens were higher than those of hCS 0 and hCS 17.5, which had demineralized surfaces.

Remineralized teeth are known to be more resistant to acidic environments because of the minerals formed during remineralization [21]. In addition, calcium and phosphate can enhance enamel remineralization [22]. Therefore, calcium ions released from hCS, which then compounded with phosphate in artificial saliva, can encourage remineralization of demineralized teeth. Therefore, the composite resin containing hCS could alkalize the acidic surroundings and produce calcium phosphate compounds, which might prevent secondary caries around the restoration.

From the current research, increasing the hCS filler content could prevent enamel demineralization with the same immersion time in artificial saliva of pH 4.0. Therefore, the first null hypothesis is rejected. In addition, the second null hypothesis was also rejected because increasing immersion time in artificial saliva of pH 4.0 could prevent enamel demineralization with the same hCS filler content.

Although bovine teeth were used in this study, they were known to have properties similar to those of humans and even to demineralization properties [23]. However, further studies on human teeth are needed to confirm the effect of hCS on enamel remineralization.

Herein, the prevention of enamel demineralization using restorative resin composites containing hCS in a cariogenic environment was reported for the first time. The results demonstrated that increasing the hCS filler level significantly increased the prevention effect of enamel demineralization compared to restorative resin composites containing conventional dental glass filler. Based on the above results, this study provides useful information for the design of in vitro tests of tooth demineralization in microleakage situations. Additionally, hCS filler appears to be a useful and promising bioactive material for incorporation into dental composite resins that prevent secondary caries around restorations.

Ethics approval and consent to participate

Not applicable

Consent for publication

Not applicable

Availablility of data and materials

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests

Funding

This work was supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea (NRF-2020R1I1A1A01051962).

Authors’ contributions

S.-Y.Y.: conceptualization, methodology, investigation, and writing the original draft; A.R.H.: data curation, validation, software and formal analysis; D.K.: data curation and validation, and software analysis; K.-M.K.: resources, validation, and editing the paper; J.-S.K.: supervision, project administration, and reviewing the paper. All authors commented on the paper and approved this manuscript.

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Enamel protection of resin composite containing hydrated calcium silicate by microleakage simulation

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Abstract

Figures

Background

Methods

Preparation of the experimental resin composites containing an hCS filler

Preparation Of Bovine Enamel Disk

Simulation Of Microgap With Resin Composite And Enamel Disk

Roughness Of The Enamel Surface

Microhardness Of Enamel Surface

Scanning Electron Microscopy/energy Dispersive X-ray Spectrometry (Sem-eds) Analysis

Polarized Light Microscopy Analysis

Statistical analysis

Results

Enamel surface roughness

Enamel Surface Microhardness

Sem-eds Analysis Of Enamel And Resin Composite Disks

Polarized Light Microscopy Analysis

Discussion

Conclusions

Declarations

References

Status:

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