Wear and morphology of infiltrated white spot lesions

Evaluation of resin infiltration for inhibiting initial caries progression: An in vitro study using Micro-Computed Tomographic analysis

Objective

To evaluate the changes in lesion depth and mineral density of resin infiltration-treated white spot lesions against a simulated oral environment using thermal and acidic challenges in vitro.

Materials and methods

Two enamel slabs were prepared from each buccal surface of permanent human premolars, for a total of 56 slabs. Artificial white spot lesions were induced. One specimen was treated with resin infiltration, while the other was used as an untreated control. A micro-CT was used to assess the lesion depth and mineral density of each specimen. Subsequently, all specimens were subjected to 10,000 cycles of thermocycling and pH cycling for 10 days before being re-evaluated using the micro-CT. Lesion depth and mineral density were examined and compared between before and after aging procedures within each group by the paired sample t-test. The independent samples t-test was utilized to compare lesion depth progression and percentage change of mineral density between groups.

Results

After aging, there was both a significant lesion depth progression and a mineral loss in the control and resin infiltration groups. Mean lesion depth progression was 132.88 ± 4.18 µm for the control group and 52.31 ± 4.16 µm for resin infiltration group. Percentage mineral density loss as a percentage for the control and resin infiltration groups were 16.1 ± 0.64 % and 8.83 ± 0.30 %, respectively. The resin infiltration group demonstrated a significantly lower mean lesion depth progression and percentage changes in mineral loss compared to the control group.

Conclusions

The lesion depth and mineral density changes in the resin infiltrated-treated group were lower than untreated white spot lesions after aging procedures using thermal and acidic challenges.

Clinical significance

Resin infiltration is a promising approach to inhibit the progression of white spot lesions related to the initial stage of dental caries.

Durability of infiltrated resin application on white spot lesions after different challenges: An ex vivo study

STATEMENT OF PROBLEM

Infiltrated resin has been widely used as a minimally invasive approach to masking white spot lesions and reinforcing demineralized enamel. Recent evidence confirms its satisfactory effect in the short term, but studies focusing on its long-term performance are lacking.

PURPOSE

The purpose of this ex vivo study was to evaluate the durability of infiltrated resin on white spot lesions after pH cycling and long-term thermocycling, staining, and toothbrushing.

MATERIAL AND METHODS

Four axial surfaces of 25 extracted human molars were sectioned and fabricated as specimens. The enamel surface of each specimen was prepared in 3 areas: sound enamel, demineralized enamel (white spot lesions), and demineralized enamel treated by infiltrated resin. Then, 4 specimens of each molar were allocated to different challenges simulating a 10-year follow-up: pH cycling, thermocycling, staining, and toothbrushing. The surface roughness, microhardness, and CIELab color values were measured before and after different treatments. A scanning electron microscope (SEM) was used to observe representative specimens. Linear mixed models were used to evaluate the effect of different treatments on microhardness, roughness, and color differences (ΔE) (α=.05).

RESULTS

Resin infiltration reduced the surface roughness and increased the microhardness of demineralized lesions, (P<.001) but the values of sound enamel at baseline were not reached. The pH cycling led to the greatest roughness values (515.6 ±56.9 nm) on resin-infiltrated lesions, followed by thermocycling (450.7 ±64.7 nm), toothbrushing (291.2 ±43.5 nm), and staining (183.6 ±49.3 nm) (all P<.001). Only pH cycling significantly decreased the microhardness of resin-infiltrated lesions (81.6 ±14.8 HV 0.2) after progressive demineralization (P<.001). No clinically identified differences were found between resin-infiltrated white spot lesions and sound enamel (ΔE=3.4 ±2.0) at baseline. However, resin-infiltrated lesions demonstrated significantly greater discoloration after pH cycling (ΔE=8.0 ±4.5, P<.001), thermocycling (ΔE=5.4 ±2.0, P=.014), and staining treatments (ΔE=10.4 ±3.2, P<.001) than sound enamel.

CONCLUSIONS

Infiltrated resin application reduced surface roughness, improved microhardness, and masked white spot lesions immediately. However, it could not reestablish the characteristics of sound enamel completely and resist chemical and mechanical challenges over time.

Influence of bioactive particles and onium salt on the physicochemical properties of experimental infiltrants

This study evaluated physicochemical properties of experimental infiltrants after addition of hydroxyapatite nanoparticles (HAp) or 58S bioactive glass (BAG) and diphenyliodonium hexafluorophosphate (DPI). The resin matrix was composed of TEGDMA/Bis-EMA (3:1), 0.5 mol% CQ, and 1 mol% EDAB. The blends received or not 0.5 mol% DPI and 10% wt BAG or HAp. Icon was used as commercial control. The groups were characterized by XRD, FT-IR spectrometry, and SEM before and after simulated body fluid (SBF) immersion for up to 7 days. Polymerization kinetics (n =3 ), water sorption and solubility (n=10), and viscosity (n = 3) were surveyed. For polymerization kinetics, the samples were polymerized for 5 min and the data were obtained from 40 s and 5 min. Statistical analysis was made using ANOVA and Tukey's test (a = 0.05). After 7 days of SBF immersion, XRD and FT-IR showed that the HAp crystalline phase was present only in the HAp groups. A lower degree of conversion (DC) and polymerization rate were observed for the Icon and BAG groups, whereas HAp showed higher values. For the BAG group, DPI increased polymerization rate and DC in 40 s. After 5 min, all groups presented DC above 80%. In groups with particles, the HAp groups exhibited higher viscosity, whereas DPI groups showed a decrease in viscosity. Icon had the highest water sorption. To conclude, BAG neither improved the physicochemical properties studied, nor did it show bioactive properties. The addition of DPI reduced viscosity caused by particle addition and also attenuated the DC decrease caused by BAG addition. The addition of bioactive particles to infiltrants should be seen with caution because they increase viscosity and may not bring major clinical improvements that justify their use. DPI might be indicated only if any component is added to the infiltrant to act as a compensation mechanism.

Surface roughness and microhardness of enamel white spot lesions treated with different treatment methods

Objective

To analyse the surface roughness and microhardness of artificial enamel white spot lesions before and after WSL formation, after treatment (Opalsutre™ microabrasion, Sylc® bioactive glass, and ICON® resin infiltration), and after pH cycling with the help of the profilometer surface roughness tester and the digital Vickers microhardness tester.

Materials and methods

Seventy-five extracted molars were used to acquire one hundred specimens. 50 specimens were randomly assigned to five groups (n = 10) for the surface roughness study: 1) Sound group, 2) WSL group, 3) micro abrasion (MA; Opalustre, Ultradent, South Jordan, UT, USA), 4) bioactive glass 45S5 Sylc powder (Sylc; Denfotex Research Ltd, Inverkeithing, UK), and 5) ICON resin infiltration (ICON; DMG, Hamburg, Germany). An additional 25 specimens were used to obtain 50 enamel slabs for the surface microhardness study, which were also assigned to the same groups. All groups underwent a final stage of pH cycling. Surface roughness and surface microhardness measurements were performed at different stages for all groups.

Results

Regarding surface roughness, ICON significantly reduced the surface roughness compared to Opalustre and Sylc, with no significant difference between Opalustre and Sylc. In terms of surface microhardness, ICON showed the highest improvement, followed by Sylc and then Opalustre. Both surface roughness and microhardness were significantly affected by demineralization, partially improved after treatment, and then regressed significantly after pH cycling.

Conclusion

ICON resin infiltrant can be considered as a superior treatment option for improving surface roughness and microhardness, while Opalustre demonstrated relatively the poorest performance compared to the other treatment options. It is noteworthy that the pH cycling procedure had an adverse impact irrespective of the treatment option used.

Management of Enamel Defects with Resin Infiltration Techniques: Two Years Follow Up Retrospective Study

Background: Developmental Defects of Enamel (DDE) represent an aesthetic, functional, and often psychological problem, especially in young patients. Infiltrative treatment with resin (Icon-DMG, Hamburg, Germany) is a minimally invasive technique based on the infiltration of high viscosity resin inside the hypomineralized enamel, modifying its optical properties. The aim of this paper is to evaluate the clinical efficacy of superficial infiltration in the treatment of white enamel defects of the anterior sector with pre-eruptive etiology and its stability over time. Methods: Thirty-three patients affected by DDE associated with mild and moderate Molar Incisor Hypomineralization (MIH), mild and moderate fluorosis, and post-traumatic hypomineralization treated with resin infiltration were retrospectively retrieved. Results: In all cases an improvement in aesthetic appearance was achieved, and the 24-month follow-up confirmed the stability of the results. However, in the cases of traumatic hypomineralization the results were not completely satisfactory. Conclusions: The superficial infiltration technique can be considered a valid minimally invasive alternative to traditional treatment of mild or moderate fluorosis and mild MIH.

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.

Color masking prediction of posterior white spot lesions by resin infiltration in vitro

OBJECTIVE

To investigate parameters that could predict the color masking effect (ME) of white spot lesions (WSLs) after resin infiltration (RI).

METHODS

Sixty extracted human teeth with natural WSLs were selected (28 premolars, 29 molars and 3 incisors). At baseline, the laser fluorescence (LF) of surrounding sound enamel (SE) and the WSLs were analyzed with DIAGNOdent. Standardized photographs were obtained under D65 and UV illuminants, from which the CIE L*a*b* color coordinates and natural fluorescence (NF) of the WSLs and SE were obtained. The color difference (ΔE₀₀) and differences of NF and LF between the SE and WSLs were calculated. The lesion dimensions (area, perimeter, width, and height) were determined. After RI, the assessments were repeated. ME was considered as the reduction of ΔE₀₀ values after RI. One-way ANOVA and the Tukey tests were used to analyze the absolute means of the LF and NF values. The t test was used to compare the ΔE₀₀ values and lesion dimensions before and after infiltration. The correlations between all parameters at baseline and ME were analyzed.

RESULTS

The absolute mean values of LF at the baseline (B) and after infiltration (I) were SE/B-3.98a, WSL/B-13.28c, SE/I-3.36a, WSL/I-7.95b (p = 0.001). The mean values for NF were SE/B-7.93a; WSL/B-6.29b, SE/I-7.93a, WSL/I-7.27a (p = 0.001). The results for ΔE₀₀ were B-11.74a, I-8.66b (p = 0.001). RI significantly reduced lesion dimensions. No correlations were observed between the baseline parameters and the ME.

CONCLUSIONS

The WSLs presented higher LF and smaller NF than SE, which were respectively reduced and increased after RI. Prediction of the masking effect by the parameters evaluated at baseline was not possible, which could be due to the choice of mainly caries lesions in posterior teeth. Nonetheless, infiltration was found suitable to mask most of the WSL.

CLINICAL SIGNIFICANCE

The color masking effect of white spot lesions after resin infiltration cannot be predicted by a previous analysis of fluorescence, color, or dimensions of the lesion.

The Use of Resinous Infiltrants for the Management of Incipient Carious Lesions: a Literature Review

AbstractThe objective of this work was to analyze scientific evidence from a literature review pertaining to the effectiveness of resinous infiltrants for minimally invasive treatment of incipient carious lesions. Studies published between 2002 and 2019 were queried from the following databases: Capes, PubMed, Medline, BBO, Lilacs and SciELO. The search keywords included "Dental Caries", "Tooth Remineralization", "Dental Leakage". Most of the studies found resin-infiltrating treatment to be a viable option for the minimally invasive treatment of incipient carious lesions; this treatment was able to fulfill the primary expected effects: inhibition of carious progression and the lesions esthetic improvement. However, some issues need to be clarified to improve the safety of this treatment because it can be recommended in clinical practice. In conclusion, the use of resinous infiltrants has been reported as promising for the treatment of incipient carious lesions. However, there is a need for long-term studies to confirm the effectiveness of this treatment to determine its applicability for clinical use. Keywords: Dental Caries. Dental Leakage. Tooth Remineralization. ResumoO objetivo desse trabalho foi analisar evidências científicas, por meio de uma revisão de literatura, sobre a eficácia do uso de infiltrantes resinosos para o tratamento minimamente invasivo de lesões cariosas incipientes. A seleção do material literário utilizado foi realizada por pesquisa sobre o tema nas bases de dados: portal de periódicos Capes, PubMed, Medline, BBO, Lilacs e SciELO, abrangendo prioritariamente, o período de 2002 a 2019. Para busca nas bases de dados foram utilizadas palavras-chave como “Cárie Dentária”, “Remineralização Dentária”, “Infiltração Dentária”, assim como suas correspondentes na língua inglesa.  A maioria dos estudos encontrados aponta o tratamento infiltrante resinoso como uma opção viável para o tratamento minimamente invasivo de lesões cariosas incipientes sendo capaz de cumprir os principais efeitos esperados: inibição da progressão cariosa e melhoria estética das lesões. Entretanto, alguns impasses necessitam ser esclarecidos para que o tratamento seja recomendado com mais segurança na prática clínica. Conclui-se que o uso de infiltrantes resinosos tem sido relatado como promissor para o tratamento de lesões cariosas incipientes, contudo há necessidade de novas pesquisas e estudos a longo prazo para confirmar sua eficácia em todos aspectos desejáveis para seu uso clínico. Palavras-chave: Cárie Dentária. Infiltração Dentária. Remineralização Dentária.

Adhesive systems effect over bond strength of resin-infiltrated and de/remineralized enamel

Background: The purpose of this study was to evaluate the effect of different bonding agents on bond-strength to demineralized enamel after remineralizing treatments and resin infiltration. Methods: Buccal enamel of 120 bovine incisors was polished and then were divided into five experimental groups: SE (sound enamel); DE (demineralized enamel); AS (demineralized enamel immersed in artificial saliva for eight weeks); NaF (demineralized enamel treated with 0.05% sodium fluoride solution (one minute) for eight weeks); Ic (demineralized enamel infiltrated with a low-viscosity resin (Icon-DGM). These groups were subdivided according to adhesive system used: self-etching adhesive Adper Easy One (3M/ESPE) and etch-and-rinse adhesive Single Bond (3M/ESPE). The composite resin blocks were fabricated using a Teflon matrix. A thermomechanical cycling machine was used to carry out the artificial aging of the specimens and thus were sectioned into sticks. The microtensile tests were performed using a universal testing machine at a cross-head speed of 1 mm/min. Data (in MPa) were subjected to two-way ANOVA and Tukey's tests (5%). Results: Significant differences were found for both factors tested and interactions (p<0.05). Tukey's test results of µTBS (mean ± SD) were: etch-and-rinse SE (28.79±3.93); DE (30.41±7.22); AS (29.03±3.33); NaF (29.81±4.06)a; Ic (29.47±5.5);  and self-etching SE (30.37±6.96); DE (14.62±4.47); AS (9.79±2.32); NaF (9.36±2.31); Ic (30.78±8.68).   Conclusions: Resin infiltration did not affect the bond strength of demineralized enamel for both adhesive systems tested. For etch-and-rinse adhesive, no differences were observed for the tested groups. For self-etching adhesive, only the resin-infiltrated group showed similar bond strength to sound enamel. Both etch-and-rinse and self-etching adhesive systems can be used in resin-infiltrated enamel, if a composite restoration needs to be further performed. In enamel that has undergone the de/remineralization process, the use of a total-etch adhesive might be preferable for the restorative procedure.

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.

Assessing the Appearance and Fluorescence of Resin-Infiltrated White Spot Lesions With Caries Detection Devices

OBJECTIVE

This in vitro study examined the effectiveness of caries detector devices in assessing the ability of resin infiltration (RI) (Icon, DMG-Hamburg, Hamburg, Germany) to improve the optical properties of enamel white spot lesions (WSLs).

METHODS AND MATERIALS

Ten caries-free third molars were used. Photographs, a subjective visual assessment of the photographs, fluorescent camera (FC) images using the Spectra (Air Techniques, Melville, NY, USA), and laser fluorescent (LF) readings using the DIAGNOdent (KaVo, Biberach, Germany) were obtained from each tooth's buccal surface. Specimens were coated with nail polish leaving a rectangular window on the buccal surface and placed in pH 4.5 lactic acid gel for two weeks to create a WSL. The WSLs were analyzed by the same methods. RI was applied to half of each WSL; final photographs were then taken, and caries detector assessments were conducted. FC images were converted to grayscale, and the fluorescent image's brightness intensity was measured using ImageJ. Data were analyzed with analysis of variance and Tukey-Kramer honestly significant difference test. Significance was set at α=0.05.

RESULTS

Subjective assessment of the photographs showed that RI improved the appearance of the WSLs so that they resembled intact enamel. Mean FC-brightness intensities for intact, demineralized, and demineralized RI-treated areas were 159.6 ± 9.2, 123.4 ± 7.2, and 160.9 ± 11.5, respectively. There were no significant differences in fluorescent intensity between the intact and RI areas ( p=0.58). The demineralized areas had significantly lower fluorescent intensity than both the RI-treated and intact areas ( p<0.001). LF values did not differ significantly between intact, demineralized, or RI-treated areas.

CONCLUSIONS

This study demonstrates the ability of RI to restore artificial WSLs to the esthetics and fluorescence of intact enamel. The FC can be used to assess the optical properties of WSLs and the impact of RI on these properties.

Treatment of various degrees of white spot lesions using resin infiltration-in vitro study

BACKGROUND

This study was conducted to evaluate the efficiency of resin infiltration to improve the color of white spot lesions (WSLs) and to estimate the effect of different numbers of etching and resin infiltrant applications on the color change of WSLs with various depths. Ninety-six sound extracted premolars were subjected to acid attack inducing different depths of WSLs. Using a DIAGNOdent, teeth were divided into four main groups according to the depth of the WSLs: shallow enamel, deep enamel, shallow dentine, and deep dentine without cavitation. Then each of the main groups was subdivided into four groups: six teeth each with different protocols of resin infiltration as follows: 1 etching + 1 infiltrant application (EA), 1 etching + 2 infiltrant applications (EAA), 2 etchings + 1 infiltrant application (EEA), 2 etchings + 2 infiltrant applications (EEAA). Spectrophotometric analysis was measured at baseline (T0), after inducing the WSLs (T1), and following resin infiltration application (T2) for each group.

RESULTS

In shallow enamel, EA produced the least mean color difference (1.62 ± 0.85), with high significant difference (P < 0.001), when compared with the clinically detectable threshold (ΔE = 3.7). While in deep enamel, EAA showed the least mean color change (1.95 ± 0.4), with P < 0.001 when compared with the critical value. Also, in shallow dentine, the least mean change was noticed with EAA (3.0 ± 0.45), with P < 0.001 when compared with the clinical color detection threshold. Furthermore, in deep dentine, EAA had the least mean difference (3.76 ± 0.6) but with no significant difference, when compared with the clinically detectable threshold.

CONCLUSIONS

As the WSL got deeper, the color of the lesion became more clinically visible. In shallow enamel, the best treatment option was one etching with one resin infiltrant application. For deep enamel and shallow dentine, one etching with two applications of infiltrant gave the best lesion masking. In deep dentine, it is advisable to perform one etching with two infiltration steps, taking in consideration that all deep dentine lesions without cavitation were partially masked, remained clinically detectable, and might require more invasive restorative procedures.

Microhardness and Roughness of Infiltrated White Spot Lesions Submitted to Different Challenges

A white spot lesion is the first clinical sign of a caries lesion and represents mineral loss from the enamel subsurface. The purpose of this study was to evaluate the microhardness and surface roughness of white spot lesions after application of a resin infiltrant and subjection to different challenges. Caries-like lesions were induced in bovine enamel discs (n=50), and the specimens were randomly divided into five study groups (n=10): demineralized enamel (negative control, G1), infiltrated enamel (G2), infiltrated enamel submitted to brushing (G3), infiltrated enamel submitted to pH cycling (G4), and infiltrated enamel submitted to artificial aging (G5). Half of each enamel surface was used as its own positive control. Roughness data were analyzed using the Kruskal-Wallis test followed by the Dunn test. Results from microhardness were analyzed by two-way analysis of variance, followed by the Tukey test for multiple comparisons. The level of significance was set at 5%. Microhardness and roughness values obtained from the test side of the specimens were significantly lower compared with the sound enamel for all groups. Microhardness values obtained for G2, G3, and G5 were not significantly different. Values found for G1 were significantly lower compared with those for G2, G3, and G5. The lowest microhardness values were observed for G4, which was significantly different from the other groups. Surface roughness was not significantly different between G2 and G3. The resin infiltrant presented superiority over the unprotected white spot lesions, as they were more resistant to mechanical and aging challenges. However, resin infiltration was not able to reestablish the properties of sound enamel and was not resistant to a new cariogenic challenge.

Evaluation of Surface Roughness Characteristics Using Atomic Force Microscopy and Inspection of Microhardness Following Resin Infiltration with Icon®

OBJECTIVE

The aim of this study was to evaluate the surface roughness via atomic force microscopy (AFM) as well as to evaluate the microhardness values of Icon^® in comparison with sound and demineralized enamel in a large subject group.

MATERIALS AND METHODS

Enamel samples were prepared from sound bovine incisors and randomly allocated into either AFM (n = 60) or microhardness (n = 60) groups. The AFM group was divided into control (n = 30) and Icon^® (n = 30) subgroups. The microhardness group was also divided into three subgroups: control (n = 20), demineralization (n = 20) and Icon^® (n = 20) groups. The demineralization and Icon^® subgroups were subjected to a demineralizing solution (pH: 4, 2 hours). Following the formation of shallow white spot lesions and application of the infiltrant, each sample was examined according to its parameter.

RESULTS

AFM images suggested that Icon^® had a significantly rougher surface than the control group. When the AFM results were evaluated numerically, it was evident that the Icon^® group possessed statistically higher Sa, Sq, mean height, and maximum deviation values compared to the control group. The mean Vickers hardness values of all groups were determined to be significantly different from one another. Hardness values in the demineralization group were determined to be significantly lower than the control and Icon^® groups. No statistically significant difference was observed between mean Vickers hardness values for the contol and Icon^® groups.

CONCLUSIONS

The present in vitro study shows that more studies are required to improve the surface quality of this infiltrant material.

CLINICAL SIGNIFICANCE

The present in vitro study shows that the resin infiltration technique results in increased microhardness of demineralized enamel. However, it was observed that the infiltrant material creates a significantly rougher surface compared to healthy, untreated enamel. (J Esthet Restor Dent 29:201-208, 2017).

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.

Bonding brackets on white spot lesions pretreated by means of two methods

OBJECTIVE

The aim of this study was to evaluate the shear bond strength (SBS) of brackets bonded to demineralized enamel pretreated with low viscosity Icon Infiltrant resin (DMG) and glass ionomer cement (Clinpro XT Varnish, 3M Unitek) with and without aging.

METHODS

A total of 75 bovine enamel specimens were allocated into five groups (n = 15). Group 1 was the control group in which the enamel surface was not demineralized. In the other four groups, the surfaces were submitted to cariogenic challenge and white spot lesions were treated. Groups 2 and 3 were treated with Icon Infiltrant resin; Groups 4 and 5, with Clinpro XT Varnish. After treatment, Groups 3 and 5 were artificially aged. Brackets were bonded with Transbond XT adhesive system and SBS was evaluated by means of a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by Tukey post-hoc test.

RESULTS

All groups tested presented shear bond strengths similar to or higher than the control group. Specimens of Group 4 had significantly higher shear bond strength values (p < 0.05) than the others.

CONCLUSION

Pretreatment of white spot lesions, with or without aging, did not decrease the SBS of brackets.

In Vitro Effects of Resin Infiltration on Enamel Erosion Inhibition

Resin-based materials that show promising effects for preventing the progression of erosion have been studied. This in vitro study evaluated the effects of applying resin-based materials, including resin infiltration, on previously eroded enamel subjected to erosive challenges. The influence of enamel surface etching prior to application of the material was also studied. Bovine enamel blocks were immersed in hydrochloric acid (HCl), 0.01 M (pH 2.3), for 30 seconds in order to form a softened erosion lesion. The blocks were then randomly divided into nine groups (n=12) and treated as follows: C = control without treatment; Hel = pit & fissure resin sealant (Helioseal Clear); Adh = two-step self-etching adhesive system (AdheSe); Tet = two-step conventional adhesive system (Tetric N-bond); and Inf = infiltrant (Icon). The Helno, Adhno, Tetno, and Infno groups received the same materials without (or with no) surface conditioning. The depth of the material's penetration into softened erosion lesions was qualitatively analyzed using reflection and fluorescence confocal microscopy. After application of the materials, the blocks were immersed in HCl for two minutes; this step was followed by immersion in artificial saliva for 120 minutes four times a day for five days (erosive cycling). Both the enamel alteration and material thickness were analyzed using profilometry, and the results were submitted to Kruskal-Wallis and Dunn tests (p>0.05). Images from the confocal microscopy showed minimal penetration of Adh/Adhno and deep penetration of Inf/Infno into the erosive lesions. The groups Hel, Adh, Inf, Tetno, and Infno resulted in the formation of a layer of material over the enamel, which was effective in inhibiting the progression of erosion. In conclusion, the infiltrant, with or without etching, was able to penetrate and protect the enamel against dental erosion. The other resin-based materials, except for the two-step conventional adhesive, were able to penetrate and inhibit the progression of erosive lesions only when they were applied after enamel etching.

Effect of resin infiltration on the nanomechanical properties of demineralized bovine enamel

Objective:

The aim of the present study was to evaluate the efficacy of resin infiltration in preventing in vitro lesion progression.

Materials and Methods:

Buccal surfaces of bovine incisors were divided into mesial and distal regions and, at the center, nail varnish was applied (1.0 mm width) to protect the enamel surface against any further treatment. In order to create artificial enamel lesions in the unprotected areas, each specimen was soaked in a demineralizing solution. After that, specimens had two enamel lesions. One lesion in each sample was etched with 15% HCl for 120 s and infiltrated with a commercial infiltrating resin for 3 min, while the other lesion was not treated (control). Each specimen was cross-sectionally halved and randomly allocated to two groups: Group 1 was immediately processed and Group 2 was submitted to a new demineralization process. The samples were analyzed by means of cross-sectional hardness measurements using a nanoindenter equipment. Hardness data were statistically analyzed by non-parametric Kruskal-Wallis and MannWhitney tests (α = 0.05).

Results:

The findings showed statistical difference between treatments at the same analyzed distance range from the outer surface of the enamel (P < 0.05).

Conclusion:

The untreated lesion showed lower hardness values for distances near the outer surface of the enamel. The resin infiltration was efficient in preventing further in vitro demineralization of bovine enamel lesions.

Stability of two resin combinations used as sealants against toothbrush abrasion and acid challenge in vitro

OBJECTIVE

To test the stability of two conventional adhesives when combined with a low-viscosity caries infiltrant used for sealing sound enamel against toothbrush abrasion and acid challenge in vitro.

MATERIALS AND METHODS

Bovine enamel discs (Ø = 3 mm) randomly assigned to three groups (n = 10/group) were etched with 37% phosphoric acid for 30 s and treated with resins of different monomer contents forming three test groups: (1) Untreated specimens (Control); (2) Infiltrant (Icon, DMG) + conventional enamel bonding adhesive (Heliobond, Ivoclar Vivadent); and (3) Infiltrant + conventional orthodontic adhesive (Transbond XT Primer, 3M Unitek). All specimens were immersed in hydrochloric acid (pH 2.6) for up to 9 days, during which they were exposed to 1825 toothbrush-strokes per day. Calcium dissolution was assessed using Arsenazo III method at 24-h intervals. Data were analyzed by Kruskal-Wallis and Wilcoxon signed ranks tests.

RESULTS

Cumulative calcium dissolution for the untreated specimens (39.75 ± 7.32 μmol/ml) exceeded the sealed groups (Icon + Heliobond: 23.44 ± 7.03 μmol/ml; Icon + Transbond XT Primer: 22.17 ± 5.34 μmol/ml). Untreated specimens presented a relatively constant calcium dissolution rate throughout the experimental period, whereas the sealed groups presented a gradual increase indicating weakening of the seal by toothbrush abrasion. Both sealed groups presented significantly lower daily calcium dissolution at all time points compared to the control, except for Group 2 on the last measurement day.

CONCLUSIONS

Low-viscosity caries infiltrant application on sound enamel prior to conventional resin application provided a protective effect against enamel demineralization, but this effect was not stable when challenged mechanically by toothbrush abrasion.

Shear bond strength of orthodontic brackets to enamel after application of a caries infiltrant

OBJECTIVE

To examine differences in the shear bond strength of orthodontic brackets on differently mineralized enamel surfaces after applying a caries infiltrant or conventional adhesive.

MATERIALS AND METHODS

A total of 320 bovine incisors were assigned to eight pretreated groups, and the shear force required for debonding was recorded. Residual adhesive was evaluated by light microscopy using the adhesive remnant index. Statistical analysis included Kolmogorov-Smirnov, analysis of variance (ANOVA), and Scheffé tests.

RESULTS

The highest bond strength (18.8 ± 4.4 MPa) was obtained after use of the caries infiltrant. More residual adhesive and fewer enamel defects were observed on infiltrated enamel surfaces. Brackets on demineralized enamel produced multiple enamel defects.

CONCLUSIONS

Acceptable bond strengths were obtained with all material combinations. A caries-infiltrant applied before bracket fixation has a protective effect, especially on demineralized enamel.

Color stability of carious incipient lesions located in enamel and treated with resin infiltration or remineralization

OBJECTIVE

In this in vitro study, the color change of artificial caries lesions in enamel was evaluated after resin infiltration (Icon(®), DMG, Hamburg, Germany) or remineralization.

METHODS

Bovine enamel specimens (n = 72) were randomly divided into four groups: G1 - exposure to demineralizing solution (32 h) and resin infiltration; G2 - immersion in demineralizing solution and remineralization cycles (8 days); G3 - demineralizing solution (negative control); G4 - healthy/non-treated enamel (positive control). The groups were subdivided and immersed in: A (saliva), B (coffee), and C (wine). The baseline color was evaluated by spectrophotometer and repeated after 4 and 8 weeks, and after polishing, at the end of 8 weeks. The variation in color (∆E) and lightness (∆L) was analyzed by anova (two-way) and Tukey tests, and Friedman and Kruskal-Wallis tests, respectively.

RESULTS

All specimens underwent color and lightness change, irrespective of immersion medium. In coffee, G2 presented the lowest mean ∆E (P < 0.05), compared with the other groups. In saliva, G3 presented the highest mean ∆E, and G2 and G4 lower ∆E means.

CONCLUSION

Lesions infiltrated with Icon(®) underwent greater color change when compared with remineralized lesions, which may represent an esthetic disadvantage for the first-mentioned treatment.

Shear bond strength of orthodontic resins after caries infiltrant preconditioning

OBJECTIVE

To investigate the influence of caries infiltrant preconditioning on the shear bond strength of orthodontic resin cements on sound and demineralized enamel.

MATERIALS AND METHODS

 Stainless-steel brackets were bonded to sound or artificially demineralized (14 d, acidic buffer, pH 5.0) bovine enamel specimens using a resin cement or a combination of caries infiltrant preconditioning (Icon, DMG) and the respective resin cement (light-curing composite: Heliosit Orthodontic, Transbond XT, using either Transbond XT Primer or Transbond Plus Self Etching Primer; light-curing resin-modified glass ionomer cement: Fuji Ortho; or self-curing composite: Concise Orthodontic Bonding System). Each group consisted of 15 specimens. Shear bond strength was evaluated after thermo-cycling (10,000×, 5°C to 55°C) at a crosshead speed of 1 mm/min, and data were statistically analyzed by analysis of variance, Mann-Whitney test, and Weibull statistics. Adhesive Remnant Index (ARI) scores and enamel fractures were determined at 25× magnification and were statistically analyzed by regression analyses (P < .05).

RESULTS

The caries infiltrant system significantly increased the shear bond strength of Transbond XT Primer, Transbond Plus Self Etching Primer, and Fuji Ortho in sound specimens, and of all resin cements except for the Concise Orthodontic Bonding System in demineralized enamel. Overall, caries infiltrant preconditioning decreased significantly the number of enamel fractures, but it did not affect ARI scores.

CONCLUSION

Preconditioning of sound and demineralized enamel with the caries infiltrant system did not impair but rather increased the shear bond strength of most orthodontic resin cements while decreasing the risk of enamel fracture at debonding.

Management of Enamel White Spot Lesions

Dental caries is a highly prevalent multifactorial disease and is a major public health problem. A goal of modern dentistry is to manage enamel white spot lesions noninvasively and effectively an attempt to prevent disease progression and improve esthetics, strength and function. The progression of caries has been tried to be curbed at initial stage only but for that only use of fluoride application was suggested but with recent developments in dental materials other remineralization options as well as noninvasive masking procedure can be performed to attain best result. This article reviews all the materials and techniques mentioned in the literature to manage the world's most common disease in its initial stage only.

How to cite this article

Joshi S, Joshi C. Management of Enamel White Spot Lesions. J Contemp Dent 2013;3(3):133-137.

Penetration depths of an infiltrant into proximal caries lesions in primary molars after different application times in vitro

BACKGROUND

Caries infiltration aims to inhibit lesion progression, by occluding the porosities within the lesion body with low-viscosity resins. The ability in hampering lesion progression is correlated with the penetration depth (PD) of the infiltrant.

AIM

This study aimed to compare the infiltration depths into proximal lesions in primary molars after different application times.

DESIGN

Noncavitated natural caries lesions (n = 83) were etched with 15% HCl for 2 min and infiltrated for 0.5, 1, 3, or 5 min. Specimens were sectioned and PD at the maximum lesion depth (LD(max)) were analysed using dual fluorescence confocal microscopy.

RESULTS

Percentage penetrations (PD/LD(max)) were significantly higher after 3 or 5 min compared with 0.5-min application (P < 0.05; Mann-Whitney test). For LD(max) <400 μm, no significant differences were observed between application times (P > 0.05). For LD(max) ≥400 μm, 3- and 5-min application resulted in significantly deeper infiltration compared with 0.5 min (P < 0.05). After 1-min application, PD was significantly lower than 5 min (P < 0.05), PD/LD(max) did not differ from all other groups (P > 0.05).

CONCLUSIONS

Natural noncavitated proximal lesions in primary molars were deeply infiltrated after 1-min application in vitro. For deeper lesions, however, more consistent results were obtained after 3 min.

Protection of sound enamel and artificial enamel lesions against demineralisation: caries infiltrant versus adhesive

OBJECTIVE

To compare the protective potential of a conventional adhesive, a caries infiltrant and a combination of both against acidic challenge in vitro.

METHODS

One-hundred-and-fifty discs from bovine lower central incisors were fabricated. Seventy-five samples remained untreated, whereas the other half was subjected to a demineralisation process (14 days, acidic buffer, and pH 5) to create artificial enamel lesions. Specimens were then radioactively irradiated, and each 15 sound and demineralised specimens were treated with a caries infiltrant (Icon, DMG), an unfilled adhesive (Heliobond, IvoclarVivadent) or a combination of infiltrant and adhesive. Specimens treated with the adhesive followed by a flowable composite (TetricEvoFlow, IvoclarVivadent) served as positive control, while untreated specimens served as negative control. All samples were then subjected to lactic acid for 3 weeks at pH 4. Loss of apatite was determined using the radiochemical method of liquid scintillation. Data were statistically analysed by Kruskal-Wallis-test, one-way ANOVA and Scheffe's post hoc tests (p ≤.05).

RESULTS

In both sound enamel and artificial caries lesions, untreated specimens showed the highest rate of apatite loss, whereas enamel treated with the adhesive and the flowable composite showed almost complete protection surface against dissolution. The caries infiltrant, the adhesive and the combination of both were able to decrease enamel dissolution, but the adhesive and the combination of adhesive and infiltrant were more effective than the infiltrant alone.

CONCLUSION

Within the limitations of this in vitro study, the application of an adhesive (alone or in combination with the caries infiltrant) is more effective to protect enamel dissolution than the infiltrant alone.