Evaluation of experimental resin infiltrant containing nanohydroxyapatite on color stability and microhardness in demineralized enamel

OBJECTIVE

The aim of the study was to evaluate the effect of the addition of 10% nanohydroxyapatite in an experimental resin infiltrant on color stability and mineral loss.

MATERIAL AND METHODS

Bovine enamel blocks were randomized into five groups (n = 27/group): SE (sound enamel); ICL (initial caries lesion); I (Icon®); E (experimental infiltrant); EH (experimental infiltrant containing 10% nanohydroxyapatite). Color evaluation (n = 15) was performed and CIEL*a*b* values were obtained at points T0 (baseline), T1 (14 days immersed on coffee solution), and T2 (28 days immersed) and data were calculated ∆E00, ∆WID, ∆L*, ∆a*, and ∆b*. Cross-sectional microhardness (n = 12) was performed and lesion area (∆S) was calculated. Images were obtained with polarized light optical microscopy at 40 × magnification (n = 5).

RESULTS

In color stability results, there was significant difference between time (14 and 28 days); ICL demonstrated significant difference among treated groups in all measures (∆L*, ∆a*, ∆b*, ∆E00, ∆WID) regardless of time; I and E demonstrated similar behavior on those measures and EH differed from I in ∆L*. For ∆S, ICL group showed a significant difference compared to I and EH groups, but did not differ from E.

CONCLUSION

The nanohydroxyapatite incorporation suggested an effective mineral recovery on initial caries lesion in depth; however, it showed high color variation, such as Icon. In terms of ∆S, I and EH had lower mineral loss, suggesting a reinforcement on initial caries lesion.

CLINICAL RELEVANCE

Commercial and experimental infiltrants containing nanohydroxyapatite present low color stability and might reinforce mineral in initial caries lesion.

Microhardness and surface roughness of resin infiltrated bleached enamel surface using atomic force microscopy: An in vitro study

to evaluate the microhardness (VHN) and surface roughness (Ra) of human enamel surface treated with resin infiltration followed by in office bleaching and to study the effect of artificial saliva (AS) storage time on the VHN and Ra of resin infiltrated enamel. Materials and methods: Eighty enamel specimens were prepared from extracted human premolar teeth. Specimens were divided into two main groups (I and II) then, they were demineralized to create white spot lesions (WSLs). Group I was divided into A and B sub groups. Group A was treated with in office bleaching material while for group B, resin infiltration (Icon) was applied after 24 h storage in AS followed by bleaching. Group II was divided into (C and D). Group C was treated like group B. Specimens in group D were stored in AS for 14 d after treatment with Icon and before application of bleaching. Atomic force microscopy (AFM) Ra analysis and VHN calculation were done. Independent T Test was used to compare between groups at P < 0.05. Results: Group B demonstrated a significant increase in VHN compared with group A. Storage time in AS showed no significant difference on VHN or Ra between groups. Conclusion: Application of resin infiltration before bleaching significantly increased VHN and slightly improved Ra of WSLs compared with bleaching alone. Application of bleaching material after 24 h or 14 days of the application of resin infiltration did not have a significant effect or surface hardness or roughness of WSLs.

Radiopacity and physical properties evaluation of infiltrants with Barium and Ytterbium addition

Radiopaque properties in the infiltrant should be interesting for clinicians to feel more confident to indicate this treatment. Thus, the aim of this study was to evaluate the effect of the incorporation of barium and ytterbium particles on the physical properties of resin infiltrants. Groups were divided according to the addition of ytterbium oxide (Y) alone (30 or 40%) or Y with barium (YB) (15/15% or 20/20% respectively) in the Icon commercial infiltrant and in the experimental infiltrant base. Digital radiography (n=5), Microradiography (n=5), Microtomography (n=3), degree of conversion (n=5), water sorption (n=16), solubility (n=16), contact angle (n=16), flexural strength (n=16), elastic modulus (n=16) and Energy dispersive X-ray Spectroscopy (n=10) were performed. Analyses were performed using the R program, with a significance level of 5%, and microradiography and Microtomography analyses were evaluated qualitatively. In groups with 30 or 40% of ytterbium, radiopacity was higher or equal to enamel. Microradiography and Microtomography appear to have more radiopacity in groups with 40% (Y). Among the groups with no particle addition, those of the experimental infiltrant presented a higher degree of conversion than those of Icon®. In most groups, there was solubility below the ISO-recommended levels. The addition of particles resulted in higher viscosity. Groups with Icon had higher flexural strength and elastic modulus than groups with experimental infiltrant. The addition of 40% (Y) improved polymerization, had low solubility, and had greater radiopacity than enamel, however negatively affected the viscosity increasing then. Experimental groups with the base showed a higher water sorption than Icon groups.

Effects of the Incorporation of Bioactive Particles on Physical Properties, Bioactivity and Penetration of Resin Enamel Infiltrant

Purpose

The resinous infiltrant lacks remineralizing activity. This research aimed to develop and evaluate bioactivity, physico-mechanical properties and penetration of resin infiltrants containing Biosilicate or nanohydroxyapatite.

Methods

Experimental resin infiltrant (ERI; 75/25 wt.% TEGDMA/BisEMA) was divided among the groups Pure Experimental (PE); ERI + Biosilicate 5 or 10% (Bio5; Bio10), ERI + 10% nanohydroxyapatite (Hap10), and Icon (DMG, Germany). Bioactivity was analyzed by SEM, EDS and FT-IR/ATR after soaking in SBF. Degree of conversion (DC), sorption and solubility (SO; SOL), flexural strength, modulus of elasticity (FS; E-modulus), contact angle (CA) and penetration were characterized. Extent of penetration was analyzed by treating white spot lesions (WSL) in human dental enamel samples with the infiltrants and subsequently analyzing specimens by confocal laser scanning microscopy. Data from each test were submitted to ANOVA and Tukey's tests (p < 0.01).

Results

SEM, EDS and FT-IR showed the formation of precipitates and increase in the rates of Ca and P in the groups with bioactive particles, after storage in SBF. Hap10 showed higher DC and CA values than all the other groups. Groups Bio5 and Bio10 showed CA values similar to those of Icon, higher SO and SOL values, and reduction in other properties. All infiltrants were capable of penetrating into the WSLs.

Conclusion

The incorporation of Biosilicate (5 or 10%) or nanohydroxyapatite (10%) into ERI induced mineral deposition on the surface and did not compromise infiltration and penetration into WSLs, however, compromising their physico-mechanical properties.

Resin Infiltration of Non-Cavitated Enamel Lesions in Paediatric Dentistry: A Narrative Review

The resin infiltration (RI) technique was introduced as one of the minimal intervention dentistry strategies in addressing dental caries among the paediatric population. This technique used the low-viscosity resin monomer to infiltrate the non-cavitated carious lesion and other developmental enamel porosities, thus allowing the conservation of the tooth structure. This narrative review aims to explore the value of RI in Paediatric Dentistry. Through our search of the literature, the development of the material, their clinical applications and shortcomings, as well as the innovation that has been carried out to improve the current RI, were discussed. There are number of high-level evidence supporting the use of RI in arresting non-cavitated proximal caries lesions in primary and permanent teeth, but its efficacy in managing anterior white spot lesions is still unclear. Limited penetration depth, not radiopaque and questionable long-term colour and material stability were among the limitation of the material. Various laboratory-based studies have been conducted to improve the current properties of RI. Nevertheless, RI has emerged as one of the important micro-invasive techniques in addressing non-cavitated and anterior white-spot enamel lesions in children and adolescents with great success.

Randomized in situ evaluation of surface polishing protocols on the caries-protective effect of resin Infiltrant

The aim of this placebo-controlled randomized in situ study was to evaluate the effect of different surface polishing protocols on enamel roughness, bacterial adhesion and caries-protective effect of a resin infiltrant. Seventy-five bovine enamel samples having artificial caries lesions were treated with a resinous infiltrant and afterwards randomly dividided into five polishing protocols: aluminum oxide flexible disks (Al₂O₃-Disks), silicon carbide tips (SIC-Tips), silicon carbide brush (SIC-Brush), silicon carbide polyester strips (SIC-Strips) or no polishing [negative control (NC)]. Average surface roughness (Ra) was assessed by profilometry. Samples were mounted in palatal appliances under a mesh for biofilm accumulation. Fifteen volunteers wore the intraoral appliances (14-days) and cariogenic challenge was triggered by sucrose solutions. Biofilm formed was collected for microbiological analysis of caries-related bacteria (Streptococcus mutans, Lactobacillus acidophilus) and demineralization was assessed by cross-sectional microhardness. Mean Knoop hardness numbers (Kg/mm²) were plotted over lesion depth (µm) and area under the lesion curve was subtracted from sound enamel to determine demineralization (ΔS, Kg/mm²xµm). Data were analyzed by ANOVA and post-hoc comparisons (α = 0.05). NC resulted in significantly higher Ra means than Al₂O₃-Disks and SIC-Strips. Bacterial counts were not significantly different between the groups (p > 0.05). Regards ΔS means, however none of the groups were significantly different to NC (6983.3 kg/mm²xµm /CI 4246.1-9720.5, p > 0.05). Conclusions: Polishing protocols (Al₂O₃-Disks, SIC-Strips) significantly decreseased roughness of infiltrated-enamel, however none of the polishing protocols could signicantly decrease bacterial counts nor resulted in significant less demineralization.

Impact of Dentistry Materials on Chemical Remineralisation/Infiltration versus Salivary Remineralisation of Enamel-In Vitro Study

The aim of this study is to evaluate salivary remineralisation versus chemical remineralisation/infiltration of enamel, using different dentistry materials. The enamel changes were studied using confocal laser scanning microscopy (CLSM), and the depth of lesions and demineralisation/remineralisation/infiltration percentage were calculated. Additionally, the macro elemental composition of the teeth was performed using atomic absorption spectroscopy (AAS). Two studies were performed: (i) demineralisation of enamel in 3% citric acid and infiltration treatment with infiltration resin (Icon, DMG), remineralisation with Fluor Protector (Ivoclar Vivadent) and artificial saliva pH 8; and (ii) enamel demineralisation in saliva at pH 3 and remineralisation at salivary pH 8. The results showed that, firstly, for the remineralisation of demineralised enamel samples, Fluor Protector (Ivoclar Vivadent) was very effective for medium demineralised lesions followed by saliva remineralisation. In cases of deep demineralisation lesions where fluoride could not penetrate, low viscosity resin (Icon, DMG, Hamburg) effectively infiltrated to stop the demineralisation process. Secondly, remineralisation in salivary conditions needed supplementary study over a longer period, to analyse the habits, diet and nutrition of patients in detail. Finally, demineralisation/remineralisation processes were found to influence the macro elemental composition of enamel demineralisation, with natural saliva proving to be less aggressive in terms of decreasing Ca and Mg content.

Colour stability of resin infiltrated white spot lesion after exposure to stain-causing drinks

Background

The resin-based materials are used extensively in esthetic restorations but are.

prone to color changes over time.

Aims

To assess the discoloration effect of red tea, Arabic coffee, and black coffee on the resin infiltrated white spot lesions (WSL). Moreover, to investigate the impact of time (1d, 3d, and 7d) on the discoloration of the resin infiltrated WSLs.

Materials and methods

Thirty-three extracted human premolar teeth were used to create WSLs, and ICON resin infiltration treatment was performed to obliterate the enamel pores. Teeth with resin infiltrated WSLs were sectioned into two halves by cutting mesio-distally and cross-sectionally at 1 mm below the CEJ. The resin infiltrated specimens was exposed to control (artificial saliva) and staining subgroups. Colour stability was assessed using the CIE L*a*b* system.

Results

Analysis of variance (p < 0.05) and Tukey’s multiple comparison tests revealed an insignificant color change in the control group. The immersion of resin infiltrated specimens at time intervals of 1 d (p < 0.001), 3 d (p < 0.001), and 7 d (p < 0.001) showed significant differences in color change.

Conclusion

Resin infiltrated WSLs showed marked color changes after exposure to red tea, black coffee, and Arabic coffee over time. Severe discoloration of the infiltrant was evident with the use of red tea compared to black coffee and Arabic coffee. This suggests that ICON resin-based composite material might not be a suitable material for WSL infiltration.

Application of Selected Biomaterials and Stem Cells in the Regeneration of Hard Dental Tissue in Paediatric Dentistry-Based on the Current Literature

Currently, the development of the use of biomaterials and their application in medicine is causing rapid changes in the fields of regenerative dentistry. Each year, new research studies allow for the discovery of additional possibilities of dental tissue restoration. The structure and functions of teeth are complex. They consist of several diverse tissues that need to act together to ensure the tooth’s function and durability. The integrity of a tooth’s enamel, dentin, cementum, and pulp tissue allows for successful mastication. Biomaterials that are needed in dentistry must withstand excessive loading forces, be biocompatible with the hosts’ tissues, and stable in the oral cavity environment. Moreover, each tooth’s tissue, as well as aesthetic qualities in most cases, should closely resemble the natural dental tissues. This is why tissue regeneration in dentistry is such a challenge. This scientific research focuses on paediatric dentistry, its classification of caries, and the use of biomaterials in rebuilding hard dental tissues. There are several methods described in the study, including classical conservative methods such as caries infiltration or stainless-steel crowns. Several clinical cases are present, allowing a reader to better understand the described methods. Although the biomaterials mentioned in this work are artificial, there is currently ongoing research regarding clinical stem cell applications, which have a high potential for becoming one of the most common techniques of lost dental-tissue regeneration in the near future. The current state of stem cell development is mentioned, as well as the various methods of its possible application in dentistry.

Minimally Invasive Therapies for the Management of Dental Caries—A Literature Review

In recent years, due to a better understanding of the caries pathology and advances in dental materials, the utilization of non-invasive and minimally invasive techniques that delay/obviate the need for traditional restorations has started gaining momentum. This literature review focuses on some of these approaches, including fluoride varnish, silver diamine fluoride, resin sealants, resin infiltration, chemomechanical caries removal and atraumatic restorative treatment, in the context of their chemistries, indications for use, clinical efficacy, factors determining efficacy and limitations. Additionally, we discuss strategies currently being explored to enhance the antimicrobial properties of these treatment modalities to expand the scope of their application.

A modified TEGDMA-based resin infiltrant using polyurethane acrylate oligomer and remineralising nano-fillers with improved physical properties and remineralisation potential

OBJECTIVES

This study aimed to modify an experimental triethylene glycol dimethacrylate (TEGDMA) based resin infiltrant using PUA oligomer and two remineralising fillers, including fluorohydroxyapatite (FHA) and fluoride-doped bioactive glass (FD-BG), to improve the mechanical and physical properties and induce remineralising potential.

MATERIALS AND METHODS

The polyurethane acrylate oligomer (PUA) was synthesised and characterised. Experimental resin infiltrant was prepared by mixing 10% of synthesised PUA with 88% TEGDMA. Water contact angle, penetration coefficient, and penetration depth were then measured. The FHA and FD-BG fillers were synthesised and characterised. To prepare nano-filled resin infiltrant, 5% of each powder was mixed with the prepared resin infiltrant. The prepared resin infiltrants were characterised to evaluate their degree of conversion, mechanical properties, water sorption, and solubility. The ion release of filled resin was also assessed. The non-infiltrated and infiltrated enamel specimens underwent fourteen days of pH-cycling, and a surface microhardness was done to assess the resistance to demineralisation.

RESULTS

The results showed that the addition of PUA to TEGDMA increased the mechanical properties and decreased water sorption and solubility. The addition of synthesised FD-BG fillers to resin infiltrant significantly improved the resistance to demineralisation of enamel samples compared with other groups (p ≤ 0.001). The FHA fillers also improved the resistance to demineralisation; however, the produced changes were not statistically meaningful (p > 0.05).

CONCLUSIONS

Based on the results, the PUA+TEGDMA+ FD-BG/FHA composite can be used as an alternative material for pure TEGDMA in enamel infiltration approaches owing to its better mechanical properties, lower water sorption and solubility, and also remineralisation potential.

CLINICAL SIGNIFICANCE

A resin infiltrant with remineralisation potential, lower water sorption and solubility and higher mechanical properties may enhance the management of early caries lesions.

Comparing Impact of Two Resin Infiltration Systems on Microhardness of Demineralized Human Enamel after Exposure to Acidic Challenge

AIM: This study compared the impact of two resin infiltration systems on microhardness of demineralized enamel before and after an acidic challenge. MATERIALS AND METHODS: A total of forty human maxillary molar teeth were used in this study. Each tooth has 4 groups (four standardized windows onto each tooth). Group A1: Untreated sound enamel surface (positive control), Group A2: Artificially demineralized enamel surface (negative control), Group A3: Icon resin infiltrating to demineralized enamel, while Group A4: Single bond universal adhesive applied to the demineralized enamel surface. All teeth were immersed in a demineralizing solution. The groups (A3 and A4) were further subdivided into two subgroups according to acidic ethanol challenge Subgroup B1: Specimens tested before an acidic challenge and B2: Specimens tested after an acidic challenge. Vickers microhardness test was done for all groups. One-way analysis of variance (ANOVA) was used to study the difference between tested groups on mean microhardness within each group. Tukey’s post-hoc test was used for pair-wise comparison between the means when ANOVA test was performed, and the significance level was set at p ≤ 0.05. RESULTS: Icon resin infiltration and single bond universal adhesive showed significantly higher mean microhardness than negative control, but significantly lower mean microhardness than positive control. However, insignificant difference was found between icon and single bond universal adhesive. After the acidic challenge, icon resin infiltration showed significantly higher mean microhardness than negative control. However, single bond universal adhesive showed insignificant difference as compared to the negative control. CONCLUSION: After an acidic challenge, icon resin infiltration was more successful than single bond universal total-etch adhesive system in microhardness. RECOMMENDATION: Icon resin infiltration technique is a promising, noninvasive approach that prevents the progress of the carious lesion.

Response of pulp cells to resin infiltration of enamel white spot-like lesions

OBJECTIVES

To investigate the trans-enamel and trans-dentinal biological effects of treating enamel white spot-like lesions (EWSLs) with resin infiltration components (RICs) on odontoblast-like cells (MDPC-23) and human dental pulp cells (HDPCs).

METHODS

EWSLs were induced in 60 enamel/dentin discs (4.0 ± 0.2 mm thick) using S. mutans. The discs were adapted into artificial pulp chambers and MDPC-23 were seeded on the dentin surface. The components of a resin infiltration system (Icon) were applied individually or in combination on the enamel surface as following (n = 10/treatment): Etch, Infiltrant, Etch+Infiltrant, or Etch+Dry+Infiltrant. The application of water or hydrogen peroxide served as negative and positive controls, respectively. After 72 h, MDPC-23 viability was evaluated. The extracts were exposed for 72 h to pre-cultured MDPC-23 and HDPCs in 96-well plates to evaluate cell viability, alkaline phosphatase activity (ALP), mineralized nodule formation (MN), and the expression of inflammatory cytokines (ICs) and mineralization-related genes (MRs). Data were analyzed by ANOVA complemented with Tukey or Games-Howell post-hocs (α = 5%).

RESULTS

Cell viability, ALP activity, and MN formation were significantly reduced in response to the RICs, presenting intermediate values compared to positive and negative controls. Likewise, ICs were upregulated, whereas MRs were downregulated. Among the RICs, the Etch component caused the most notorious detrimental effects.

SIGNIFICANCE

Resin infiltration of EWSLs negatively affected the metabolism of pulp cells in vitro. Therefore, even though resin infiltration is a micro-invasive therapy for non-cavitated caries in enamel, it should be closely followed up seen that components may diffuse and unbalance pulp homeostasis.

Can composition and preheating improve infiltrant characteristics and penetrability in demineralized enamel?

The composition of infiltrants can influence their physical properties, viscosity and depth of penetration (DP). Strategies are used to increase the DP, such as the addition of diluents or the use of heat. This study aimed to evaluate the effect of preheating and composition on physical properties and DP of infiltrants in demineralized enamel. The groups were assigned, and the following experimental formulations were made: 25%BisEMA +75%TEGDMA; 25%BisEMA +65%TEGDMA +10%ethanol; 25%BisEMA +65%TEGDMA +10%HEMA; 100%TEGDMA; 90%TEGDMA +10%ethanol; 90%TEGDMA +10%HEMA. The samples were photoactivated at two temperatures (25°C and 55°C). Degree of conversion (DC) was performed using an infrared spectrophotometer. Elastic modulus (E), flexural strength (FS) and contact angle (CA) tests were also performed. The DP of an infiltrant in demineralized enamel was determined by confocal laser scanning microscopy (CLSM) using an indirect labeling technique. The data were analyzed by two-way ANOVA and Tukey's test. DC increased after preheating in all the groups; however, 90%TEGDMA+10%ethanol showed the lowest DC for both temperatures, and the lowest E. Preheating did not influence E or FS. The CA increased at 55°C for most groups, but decreased for groups containing HEMA. Temperature did not seem to influence DP, and Icon showed the lowest DP values. The 100%TEGDMA composition showed more homogeneous penetration, whereas Icon showed heterogeneous and superficial penetration. The preheating technique does not improve all properties in all the material compositions. The composition of a material can influence and improve its properties.

Effect of resin infiltration application on early proximal caries lesions in vitro

Background/purpose

Resin infiltration (RI) material ICON is used in treating early proximal caries lesions, as it depends on a micro-invasive infiltration technology. This in vitro study aimed to evaluate the effect of ICON resin infiltration (RI) on early proximal caries by comparing surface roughness and hardness before and after treatment with RI using atomic force microscopy (AFM), automated microhardness testing system (AMHTS), and scanning electron microscopy (SEM) in vitro.

Materials and methods

Twenty seven premolars extracted for orthodontic reasons were sectioned buccolingually, creating 54 specimens. Each specimen was immersed in demineralizing solution to induce caries. Only teeth with "International Caries Detection and Assessment System" codes 1 and 2 were selected. The specimens were divided randomly into either AFM, AMHTS or SEM groups, which examined demineralized enamel before and after treatment with ICON.

Results

The mean average surface roughness and root mean square roughness values of demineralized enamel treated with ICON were significantly higher than untreated lesions (P < 0.001). The mean Vickers hardness values for demineralized enamel treated with ICON was significantly higher than untreated lesions (P < 0.001). SEM showed irregular, pitted and rough demineralized enamel surface with destruction of enamel rods and dissolution of enamel crystals. After ICON application, the surface showed complete blockage of enamel rods with RI and irregular, rough uneven topography.

Conclusion

RI application on proximal incipient caries increased surface roughness and hardness significantly.

Pediatric Dentists' Educational Experiences, Attitudes, and Professional Behavior Concerning Resin Infiltration: Implications for Dental Education

Minimally invasive dentistry (MID) is receiving increased attention. Resin infiltration (RI) is one micro-invasive technique for treating initial caries by sealing white spot lesions on tooth surfaces. The aims of this study were to assess pediatric dentists' RI-related educational experiences, attitudes, and professional behavior and to determine if their educational experiences were significantly related to their professional attitudes and behavior regarding RI. This cross-sectional study used an online survey to collect data from members of the American Academy of Pediatric Dentistry (AAPD) in March-April 2017. Of the 2,367 AAPD members invited to participate, 43 emails could not be delivered, and 273 surveys were completed, for a response rate of 11.8%. While only 9% of the 273 respondents reported that their classroom-based dental education had informed them about RI and only 1% that it had prepared them well to use RI with pediatric patients, higher percentages said they had been informed/prepared well by their classroom-based (24%) and clinical residency education (12%). The majority wanted to learn more about RI (71%) and would like to take a related CE course (59%). The respondents' average RI-related attitudes were positive (on five-point scale with 1=worst attitude: Mean=3.84). Regarding use of RI, 28% of respondents said they used RI sometimes and 4% often/very often, with 64% considering implementing RI in their clinics. Graduation year did not correlate with RI attitudes and use. However, the more education about RI the respondents had received during their residency (r=0.20; p<0.01) and in professional development after graduation (r=0.34; p<0.001), the more they used RI in their own work. This study found that the pediatric dentists' RI-related education was positively correlated with their professional behavior. Increasing predoctoral, resident, and continuing professional education about RI should therefore be considered.

Is Resin Infiltration a Microinvasive Approach to White Lesions of Calcified Tooth Structures?: A Systemic Review

Aim

The treatment of white lesions should aim at arresting the lesion progression of carious lesions and improving the esthetics by diminishing the opacity of the developmental disturbances of a tooth. The objective of this review was to present the scientific basis, the principles of resin infiltration and to discuss its inherent clinical applications.

Data sources

Data were identified by PubMed searches. Papers published in English between 2010 and 2015 were selected and most up-to-date or relevant references were chosen.

Conclusion

The resin infiltration technique, while promising, needed more clinical evidence for conclusive findings. However, based on available laboratory and clinical studies, it seems convincing that resin infiltration of enamel lesions should aim at arresting the progression of white spot lesions. Combining this microinvasive approach with a substantial caries remineralization program may provide therapeutic benefits and significantly reduce both long term restorative needs and costs, thus complementing the concept of minimum intervention dentistry.

How to cite this article

Manoharan V, Kumar AS, et al. Is Resin Infiltration a Micro invasive Approach to White Lesions of Calcified Tooth Structures?: A Systemic Review. Int J Clin Pediatr Dent 2019;12(1):53-58.

Testing the Clinical Applicability of Resin Infiltration of Developmental Enamel Hypomineralization Lesions Using an In Vitro Model

Aim

The aim of this study is to investigate the penetration abilities of a commercially available low-viscosity resin infiltrant into developmentally hypomineralized teeth in vitro.

Materials and methods

Four extracted third molars of a 17-year-old patient with signs of developmental enamel hypomineralization (discoloration, increased opacity, and surface roughness) were infiltrated with a low-viscosity resin mixed with a fluorescent dye, according to the manufacturer's standard protocol. Four extracted molars with sound enamel or showing only initial fissure caries were used as a control group. Specimens were embedded in polymethylmethacrylate, and grindings were prepared. High-resolution projectional radiography of the grindings was performed, and, for one specimen, quantitative micro-computed tomography was used to measure hydroxyapatite density in enamel and dentin lesions. After decalcification, the grindings were examined by reflected bright-field microscopy, wide-field fluorescence microscopy, and confocal laser scanning microscopy. Fluorescence micrographs were superimposed on the radiographs and analyzed correlatively.

Results

The pattern of hypo-/demineralization in enamel and dentin in developmentally hypomineralized teeth showed a good congruence with the pattern of resin infiltration. Cavitations and dentin tubules up to a depth of 2 mm beyond cavitations were filled by the infiltrant. In control teeth, the penetration of the infiltrant was limited to decalcified enamel areas (initial fissure caries).

Conclusions

In vitro infiltration of developmentally hypomineralized enamel was successful.

Clinical significance

Resin infiltration might be considered as a routine procedure in the treatment of developmentally hypomineralized teeth. Further investigations with higher sample sizes, different degrees of severity, different stages of lesion extension, and modified treatment protocols are necessary.

How to cite this article

Schnabl D, Dudasne-Orosz V, et al. Testing the Clinical Applicability of Resin Infiltration of Developmental Enamel Hypomineralization Lesions Using an In Vitro Model. Int J Clin Pediatr Dent 2019;12(2):126-132.

Concealment effect of resin infiltration on incisor of Grade I molar incisor hypomineralization patients: An in vivo study

Context

Molar incisor hypomineralization (MIH) is a commonly occurring esthetic setback among patients. Depending on the graveness of the lesion, esthetics of MIH can be improved by treatments such as enamel microabrasion, bleaching, composite resin bonding, and the combination of some or all of these techniques.

Aim

The aim of this study is to evaluate the esthetic results of resin infiltration treatment on incisors with Grade I molar incisor MIH.

Materials and Methods

A total of 22incisor lesions with MIH were infiltrated with resin. Photographs were captured before infiltration, just after infiltration, and 6 months after infiltration. The photographic evaluation was done by the CIE L*a*b* scoring method. The means of each parameter such as ΔL and ΔE were calculated.

Statistical Analysis

ANOVA in conjunction with Turkey's post hoc test was used to evaluate the means.

Results

The total color change observed was equal just after treatment and 6 months after treatment, with no statistically significant difference (P = 0.87) between these two time points. The mean of difference in total color change (ΔE₃) of white tooth discoloration was 13.2 SD 6.8, showing an overall color change.

Conclusion

Infiltration can conceal the white opaque appearance of Grade I MIH lesions, and also reduction in lesion whiteness is seen with time.

Effect of monomer blend and chlorhexidine-adding on physical, mechanical and biological properties of experimental infiltrants

OBJECTIVES

The aim of the study was to evaluate antimicrobial inhibition zone, degree of conversion (DC) and Knoop hardness (KH) of experimental infiltrants. Experimental low viscosity monomer blends were prepared and chlorhexidine diacetate salt (CHX) (0.1% or 0.2%) was added comprising the groups: G1) TEGDMA; G2) TEGDMA/0.1CHX; G3) TEGDMA/0.2CHX; G4) TEGDMA/UDMA; G5) TEGDMA/UDMA/0.1CHX; G6) TEGDMA/UDMA/0.2CHX; G7) TEGDMA/BISEMA; G8) TEGDMA/BISEMA/0.1CHX; G9) TEGDMA/BISEMA/0.2CHX. Icon^® was used as control group.

METHODS

Specimens of resin blends were made (n=9) to accomplished DC and KH. Pour plate was accomplished to evaluate antimicrobial groups' activity against Streptococcus mutans (SM) and Lactobacillus acidophilus (LA). Data obtained were submitted to two-way ANOVA and Tukey tests for blends comparisons and Dunnett's test for comparisons between experimental infiltrants and Icon^® (p<0.05).

RESULTS

In relation to antimicrobial effect, uncured blends showed higher antibacterial activity than cured ones for the most of blends. After polymerization, G5 showed the highest inhibition zone against SM and, G3 and G6 against LA. Concerning KH, TEGDMA/UDMA-based blends showed the highest values of KH number and it was influenced by monomeric base, regardless CHX concentration. DC was not affected by monomer blend composition, neither for CHX concentration. The antimicrobial activity was affected by monomeric base, CHX concentration and polymerization. Experimental infiltrants presented similar or higher performance than Icon^® for the properties evaluated.

SIGNIFICANCE

White spot lesion infiltration with low viscosity monomer blends (infiltrants) is an alternative to stop initial caries lesions progression. The incorporation of an antimicrobial agent as chlorhexidine diacetate salt in infiltrants composition could enhance the performance of these materials.

Surface Roughness of Initial Enamel Caries Lesions in Human Teeth After Resin Infiltration

BACKGROUND

Low viscosity resin infiltration of initial caries lesions is a modern microinvasive method to treat initial cries lesions. However, only scarce information is available about the long-term surface alterations of infiltrated lesions.

METHODS

Twenty-eight premolar teeth exhibiting non-cavitated initial caries lesions (International Caries Detection and Assessment System (ICDAS code 1&2)) were divided into two groups, one of which was infiltrated with resin, and the other remained untreated. The teeth underwent two thermocycling procedures. The surface roughness was determined quantitatively, and the results were evaluated statistically. In addition, the surfaces of the lesions were investigated by scanning electron microscopy (SEM), and the surface was analyzed visually with respect to surface irregularities.

RESULTS

The results showed a reduction in the surface roughness that was significant after 2500 thermocycles compared to the untreated surface. In the control specimens, no change in the surface roughness was found. The qualitative SEM data also showed a smooth surface after thermocycling, which supported the statistical findings.

CONCLUSION

After thermocycling, resin-infiltrated enamel surfaces become smoother and had no additional risk for plaque accumulation.

Surface Properties and Color Stability of Resin-Infiltrated Enamel Lesions

OBJECTIVES

To examine the surface topographies, microhardness, and color stability of resin-infiltrated enamel lesions before and after aging challenges in vitro using three-dimensional laser scanning profilometry, surface microhardness testing, spectrophotometry, and scanning electron microscopy.

METHODS

Forty human third molars were embedded in epoxy resin, and each tooth was prepared to have two white spot lesions and one sound enamel area. One white spot lesion received resin infiltration and the other was untreated. Ten specimens were subjected to thermocycling for 10,000 cycles, 10 specimens were immersed in coffee solutions, and 10 specimens were placed in water storage. Surface area roughness (Sa), Vickers microhardness (VHN), and CIE L*a*b* color values were measured on sound enamel, resin-infiltrated lesions, and untreated lesions before and after aging. The surface morphology of resin-infiltrated lesions was observed after aging under scanning electron microscopy and compared with 10 specimens that were not subjected to aging challenge.

RESULTS

Resin infiltration increased the surface microhardness of the enamel lesions from 89.3 to 212.0 VHN. The surface microhardness of resin-infiltrated enamel lesions was not significantly affected by aging. The surface roughness of resin-infiltrated lesions (0.32-0.37 μm) was greater than that of sound enamel (0.05-0.06 μm) and untreated lesions (0.12-0.13 μm). Thermocycling and water storage further increased surface roughness of resin-infiltrated surfaces. Resin-infiltrated enamel lesions showed greater discoloration than sound enamel surfaces. Surface microfissures and microcracks were observed on resin-infiltrated enamel lesions after thermocycling.

CONCLUSIONS

Surface hardness of enamel lesions increased significantly after resin infiltration and remained stable following thermocycling. Surface roughness and color stability of resin-infiltrated enamel lesions were less than ideal and might further deteriorate after aging in the oral environment.

Evaluation of sorption/solubility, softening, flexural strength and elastic modulus of experimental resin blends with chlorhexidine

OBJECTIVES

To evaluate physical-chemical properties of experimental diacetate chlorhexidine (CHX)-added resin blends.

METHODS

Blends were formulated: G1)TEGDMA; G2)TEGDMA/0.1%CHX; G3)TEGDMA/0.2%CHX; G4)TEGDMA/UDMA; G5)TEGDMA/UDMA/0.1%CHX; G6)TEGDMA/UDMA/0.2%CHX; G7)TEGDMA/BisEMA, G8)TEGDMA/BisEMA/0.1%CHX; G9)TEGDMA/BisEMA/0.2%CHX. Icon(®) was the control group. For sorption/solubility (SS), cylindrical specimens (n=5) were prepared and their weight obtained. The specimens were immersed in deionized water for 7days at 37°C and their weight was verified again. SS were calculated using accepted formulas. For softening, cylindrical specimens (n=10) were prepared and initial Knoop hardness number (KHN) obtained. The specimens were immersed in absolute ethanol for 24h at 37°C and final KHN accomplished. Softening values were calculated by KHN reduction percentage. For elastic modulus (EM) and flexural strength (FS) bar specimens were prepared (n=10) and values obtained with a universal device (three point, 5mm distance, 0.5mm/min, load of 50N). The data was analyzed using one-way ANOVA and Tukey test (α=5%).

RESULTS

TEGDMA/BisEMA blends and Icon(®) showed the lowest sorption from blends (p>0.05), and Icon(®) was the most soluble material (p<0.01). TEGDMA/UDMA/0.1%CHX showed the highest softening, similar to Icon(®) (p>0.05). For EM, all blends were different than Icon(®) (p<0.01). For FS, TEGDMA blends were similar to Icon(®), showing the lowest averages (p>0.05).

CONCLUSIONS

Monomers chemical characteristics influenced the physical-chemical properties of experimental blends more than CHX. Between the blends tested, UDMA blends presented satisfactory results for assays evaluated.

CLINICAL SIGNIFICANCE

Infiltrants CHX-added could arrest and reinforce initial caries lesions, and the antimicrobial effect could prevent new lesions in sound enamel adjacent to the infiltrated area.

Effectiveness of resin-based materials against erosive and abrasive enamel wear

OBJECTIVE

The objective of this study was to test the effectiveness of resin-based materials against erosive enamel wear under erosive and abrasive challenges by orange juice and tooth brushing.

METHODS

Fifty enamel specimens from third molars were assigned to five groups: ICON resin infiltration with no etching (ICON-NE), ICON resin infiltration with 15 % HCl etching (ICON-AE), Seal & Protect sealant (S&P), Tetric EvoFlow (TEF), and control. Erosive lesions were first created on enamel, then treated with resin-based materials. Erosive and abrasive challenges by orange juice and tooth brushing were repeated after treatments. Erosive wear of the treated areas was measured with 3D scanning microscopy, and data were analyzed using ANOVA and paired t tests.

RESULTS

Treatments with ICON, S&P, and TEF created a protective material coating of 4.5 ± 1.9 μm, 44.3 ± 8.1 μm, and 84.6 ± 15.7 μm in thickness on the lesion surfaces, respectively. After 15 cycles of erosive and abrasive challenges, enamel or material losses were 21.9 ± 2.3 μm for control, 24.5 ± 4.0 μm for ICON-NE, 24.6 ± 7.4 μm for ICON-AE, 11.2 ± 4.1 μm for S&P, and 3.9 ± 1.9 μm for TEF, respectively. The protective coatings were completely lost in the ICON infiltration groups but remained intact in both the S&P and TEF groups after erosive and abrasive challenges.

CONCLUSION

In contrast to a resin sealant and a flowable composite, ICON infiltration resin was not effective in protecting enamel surfaces from erosive and abrasive wear.

CLINICAL RELEVANCE

Sealant and flowable composite resin may create protective coatings on eroded enamel surfaces and prevent further tissue loss.

Evaluation of Stain Penetration by Beverages in Demineralized Enamel Treated With Resin Infiltration

PURPOSE

To evaluate stain penetration by different beverages in artificially demineralized human teeth treated with resin infiltration.

METHODS AND MATERIALS

Sixty extracted human permanent molars were demineralized, treated with resin infiltration (Icon), and immersed in four different beverages (coffee, grape juice, iced tea, and distilled water; N=15) for four weeks. After aging, teeth in the distilled water group were stained with 2% methylene blue for 24 hours. All teeth were sectioned, and stain penetration was evaluated under light microscopy. Chi-square test, independent and paired sample t-test, analysis of variance with the Fisher least significant difference post hoc test, and the Kruskal-Wallis test were used to analyze the results (p<0.05).

RESULTS

Resin infiltration-treated surfaces (Icon surfaces) had statistically significant fewer samples with presence of stain penetration compared to untreated surfaces (control surfaces) (p<0.001). There was also a significant decrease in depth of stain penetration in Icon surfaces compared to the control surfaces (p<0.001). Among tested beverage groups, iced tea showed significantly greater depth of stain penetration (0.134±0.029 mm), followed by grape juice (0.118±0.047 mm), methylene blue (0.022±0.019 mm), and coffee (0.008±0.017 mm; p<0.001).

CONCLUSION

Both Icon and control surfaces exhibit stain penetration by different beverages (iced tea, grape juice, and coffee). However, resin-infiltrated enamel surfaces allow significantly less depth of stain penetration compared to untreated surfaces. The iced tea group presents greatest depth of stain penetration, followed by grape juice, methylene blue, and coffee.

Resin Infiltration of Fissure Caries with Various Techniques of Pretreatment in vitro

The resin infiltration technique might be used for occlusal caries lesions in order to arrest their progression. This in vitro study evaluated the influence of various modifications of the infiltration technique on the penetration abilities of the infiltrant into occlusal lesions. Extracted human molars and premolars (n = 140) with non-cavitated white spot lesions were randomly allocated to 7 groups. As control, specimens were etched with 15% hydrochloric acid (HCl) gel for 120 s and resin infiltrated for 180 s (Icon; DMG). As modification HCl gel reduced in surface tension and viscosity with and without abrasives was applied using 3 different types of brushes either to oscillate or rub the HCl gel onto the enamel surface. The median maximum lesion depth was 1,232 µm (interquartile range 882-1,513). Compared with the control procedure [23% (16/50)] a higher percentage penetration was observed if the HCl gel was mixed with a small amount of abrasives were rubbed into the fissures using a modified brush with stiff bristles that were adjusted to the fissure relief for either 120 s [100% (64/100)] or 30 s [98% (61/100); p < 0.05; Mann-Whitney test]. All other experimental treatments resulted in penetration results in-between. It can be concluded that the use of an abrasive HCl gel in conjunction with a modified brush mostly enhances resin infiltration into fissure caries lesions. © 2014 S. Karger AG, Basel

Modification of surface pretreatment of white spot lesions to improve the safety and efficacy of resin infiltration

Objective

A low-viscosity resin (infiltrant) was used to inhibit the progression of white spot lesions (WSLs) and resolve associated esthetic issues. An alternative pretreatment was explored to increase the pore volume of the surface layer of the WSLs. Also, the penetration effects of the infiltrant were evaluated for various pretreatments.

Methods

Sixty two artificial lesions were fabricated on bovine teeth. As a positive control, 15% HCl gel was applied for 120 seconds. Further, 37% H₃PO₄ gel was applied for 30 seconds using three methods. The samples were divided as follows: H₃PO₄ only group, H₃PO₄ sponge group, and H₃PO₄ brush group. The acid was gently rubbed with the applicators (i.e., a sponge or brush) throughout the application time. To compare the effects of resin infiltration, twenty paired halves of specimens were treated with an infiltrant (ICON®).

Results

Thicknesses of the removed surface layers and infiltrated areas were evaluated by confocal laser scanning microscope. The positive control and the 37% H₃PO₄ brush group failed to show significant differences in the removed thickness (p > 0.05); however, the mean percentage of the infiltrated area was higher in the 37% H₃PO₄ brush group (84.13 ± 7.58%) than the positive control (63.51 ± 7.62%, p < 0.001). Scanning electron microscope observations indicate higher pore volumes for the 37% H₃PO₄ brush group than for the positive control.

Conclusions

Application of 37% H₃PO₄ with a brush for 30 seconds increased the pore volume of WSL surface layers and the percentage of infiltrated areas in comparison to the use of 15% HCl for 120 seconds.

Resin infiltration into differentially extended experimental carious lesions

Resin infiltration of initial caries lesions is a novel method of caries therapy. However, it has some limitations. Therefore, further experimental studies are needed to improve resin infiltration. It was the aim of this investigation to study resin infiltra-tion into different experimental carious lesions. Caries-free extracted human molars and premolars were demineralized for 3, 6, 9 and 12 days and infiltrated with resin. Prior to infiltration, the teeth were incubated with sodium fluorescein. After em-bedding, serial sections were cut through the experimental lesions, and the penetration of the resin was measured with fluo-rescence microscopy. Two infiltrated teeth from each time interval were not embedded and cut. Infiltration of the resin was then studied with EDS element analysis. The results showed that with increasing demineralization time, the lesion expansion was also increasing, and the resin infiltration was always almost complete. From these results it can be concluded that artifi-cial standardized caries-like lesions are suitable for experimental studies of resin infiltration.

Solvent content and dentin bond strengths using water-wet, ethanol-wet and deproteinization bonding techniques

OBJECTIVES

To evaluate the impact of solvent content in two-step, etch-and-rinse adhesives on the dentin bond strengths obtained via water-wet, ethanol-wet or deproteinization techniques.

MATERIALS AND METHODS

A model photocurable Bis-GMA/HEMA blend was diluted in ethanol (7.5, 15 or 30 mass%) or acetone (15, 30 or 60 mass%) (low, medium or high solvent content, respectively). Viscosity of the solutions was measured with an oscillatory viscometer and data analyzed using ANOVA on Ranks (5%). Dentin bond strengths were evaluated using microshear bond test. After acid-etching and rinsing, the dentin was kept wet (water-wet), treated with ascending ethanol concentrations (ethanol-wet) or with 10% NaOCl solution (deproteinization). Composite cylinders built-up on the surfaces for the microshear test. Data from each bonding technique were submitted to two-way ANOVA and Fisher's LSD method (5%). Failure modes were classified under magnification and data analyzed using chi-square tests (5%).

RESULTS

Viscosity of ethanol-based agents was remarkably higher than acetone solutions. For the water-wet technique, lower bond strength was observed for the low compared with medium and high ethanol contents. For the ethanol-wet technique, the bond strength for both solvents types was low < medium = high solvent content. For the deproteinization technique, no significant differences were observed among groups. Significant differences in failure modes were observed between the bonding techniques. The ethanol-wet technique had more adhesive failures, whereas the other techniques showed a predominance of mixed failures.

CONCLUSIONS

The solvent content may interfere with the dentin bond strengths for the conventional and ethanol bonding techniques.

Micro-hardness and mineral loss of enamel lesions after infiltration with various resins: influence of infiltrant composition and application frequency in vitro

OBJECTIVES

The aim of this in vitro study was to evaluate the influence of infiltrant composition and application frequency on micro-hardness and lesion progression after resin infiltration of artificial enamel lesions.

METHODS

In each of 100 bovine enamel samples, three artificial caries lesions were created (pH=4.95, 50 days). After etching two of the lesions (37% phosphoric acid) specimens were randomly allocated to five infiltrants (four experimental infiltrants with different monomer and solvent compositions and penetration coefficients, and one commercial infiltrant [Icon, DMG]). Lesions were then infiltrated and light-cured, and infiltration repeated afterwards for one of the lesions. Infiltrated samples were cut into halves, with one half being demineralised for further 50 days. Micro-hardness (VHN) and integrated mineral loss (ΔZ) were evaluated at baseline and after second demineralisation. Repeated measures ANOVA and paired t-tests were used to analyse influence of material composition and application frequency on micro-hardness and lesion progression (integrated mineral loss difference ΔΔZ).

RESULTS

Resin infiltration significantly increased micro-hardness and reduced lesion progression compared to untreated artificial lesions (p<0.05, t-test). Neither micro-hardness nor lesion progression were significantly influenced by material composition (p>0.05, ANOVA). In contrast, twice application resulted in significantly increased micro-hardness and demineralisation resistance of infiltrated lesions (p<0.05, ANOVA).

CONCLUSION

Resin infiltration significantly improves micro-hardness and demineralisation resistance of enamel lesions; these effects are significantly enhanced if resins are applied twice. Experimental resins did not outperform the commercial infiltrant.

CLINICAL SIGNIFICANCE

This in vitro study demonstrated that resin infiltration significantly increases both micro-hardness and demineralisation resistance of enamel caries lesions. Twice application of the infiltrant seems to increase these effects. In contrast, the composition of the infiltrant had no significant influence on investigated parameters.

Minimal intervention dentistry: part 6. Caries inhibition by resin infiltration

Resin infiltration has made possible an innovative way of treating initial carious lesions that fits perfectly with the concept of minimal intervention dentistry. Infiltration of carious lesions represents a new approach to the treatment of non-cavitated lesions of proximal and smooth surfaces of deciduous and permanent teeth. The major advantage of this method is that it is a non-invasive treatment, preserving tooth structure and that it can be achieved in a single visit. While this therapy can rightly be categorised as minimum intervention dentistry, clinical experience is limited and further controlled clinical trials are required to assess its long-term results. The inhibition of caries progression by resin infiltration should now be considered an alternative to invasive restorations, but involves early detection of lesions and does not allow for appropriate monitoring of the caries risk.

Influence of caries infiltrant contamination on shear bond strength of different adhesives to dentin

OBJECTIVES

To analyze whether the contamination with a caries infiltrant system impairs the adhesive performance of etch-and-rinse and self-etching adhesives on dentin.

MATERIALS AND METHODS

Dentin contamination with the caries infiltrant system (Icon, DMG) was simulated by applying either hydrochloric acid (15 % HCl, Icon Etch, 15 s), the resin infiltrant (Icon infiltrant, 4 min), or both prior to the application of the respective adhesives (each group n = 10). In the control groups, the etch-and-rinse adhesive (Optibond FL, Kerr) and the self-etching adhesive (iBOND Self Etch, Hereaus) were applied without former contamination with the infiltrant system. Additionally, the adhesive performance of the resin infiltrant alone was tested. Shear bond strength of a nano-hybrid composite was analyzed after thermocycling (5,000×, 5-55°C) of the specimens and analyzed by ANOVA/Scheffé post hoc tests (p < 0.05) and Weibull statistics. Failure mode was inspected under a stereomicroscope at × 25 magnification.

RESULTS

Contamination with the resin infiltrant alone did not impair shear bond strength, while contamination with hydrochloric acid or with hydrochloric acid and the resin infiltrant reduced shear bond strength (MPa) of the adhesives (Optibond FL: 20.5 ± 3.6, iBOND Self Etch: 17.9 ± 2.6) significantly. Hydrochloric acid contamination increased the number of adhesive failures. The adhesive performance of the caries infiltrant system alone was insufficient.

CONCLUSION

The contamination with the caries infiltrant system impaired the shear bond strength of conventional dental adhesives.

CLINICAL RELEVANCE

Contamination of the caries infiltrant system on dentin should be avoided due to the detrimental effect of hydrochloric acid etching.

Light- and electronmicroscopic study of infiltration of resin into initial caries lesions--a new methodological approach

It was the purpose of this pilot study to investigate resin infiltration into various types of initial subsurface caries lesions using a combined microscopic technique with polarized light microscopy and fluorescence microscopy and subsequent scanning microscopy with EDX-element analysis. Six extracted premolars with initial caries lesions were used. Five were infiltrated with resin after imbibition of the subsurface carious pore volume of enamel with sodium fluorescein solution. After light curing the unbound dye was removed by washing out in water. Serial sections were cut through the lesions and investigated with polarized light microscopy, fluorescence microscopy and simultaneously with both microscopic techniques. The same sections were then studied with scanning electron microscopy and EDX-element analysis to prove the infiltration of the resin into the lesions. The results showed, that the combination technique adds further morphologic information to infiltration behaviour of the resin. The individual volume of early acute lesions versus chronic lesions involving dentin, and the fluorescein bound by resin was well documented in serial sections. The EDX calcium and phosphorus signals correlate negatively with the lesion extension, and the carbon signal correlates positively, thus labelling the resin infiltration. It could be demonstrated that resin infiltration is dependent from the pore volume of the lesion. It can be concluded that the combined polarized light microscopy with fluorescence microscopy is an advantageous tool for studying infiltration of resin into hard tissues.

Infiltrants inhibit progression of natural caries lesions in vitro

To define the optimized material properties of caries-infiltrating resins (infiltrants), we evaluated the effects of infiltrant composition and penetration coefficient (PC) on the inhibition of the progression of natural approximal caries lesions in vitro. Non-cavitated natural enamel lesions were etched (15% HCl gel) and infiltrated for 5 min with experimental resins varying in PC (cm/sec): PC63, PC185, PC204, and PC391. As a positive control (PosC), lesions were covered with flowable composite resin, whereas untreated lesions served as negative controls (NegC). Specimens were exposed to a demineralizing solution (pH 4.95) for 400 days. Progression of mineral loss was analyzed by transverse wavelength-independent microradiography. Percentage progressions of NegC [median (25th/75th percentile), 24 (10/56)], PC63 [9 (3/39)], and PC185 [12 (9/24)] were significantly higher compared with those of PosC [1 (-8/8)], PC204 [-2 (-4/2)], and PC391 [0 (-5/9)] (p < 0.05). Thus, infiltrants with PC > 200 cm/sec are capable of inhibiting lesion progression.