Minimally Invasive Technique of Masking Nonpitted Fluorosis on Young Permanent Incisors: A Clinical Trial

INTRODUCTION

White spot lesions due to dental fluorosis pose serious esthetic problem in newly erupted permanent incisors. As a child approaches early adolescence, there is an alteration in the attitude and self-perception under the influence of peer pressure. This affects their emotional stability and self-confidence. Hence, this age group is more concerned about esthetics and they seek quick intervention, which should be permanent and less invasive. Also the awareness of modern Indian parents toward dental esthetics is increasing and they demand natural appearance of teeth with tooth-colored restorations for their children.^1–3 The resin infiltration concept supports the concept of preventive dentistry by restoring the tooth in a least invasive way for regaining healthy, functional, and esthetic smiles.⁴ The present study was conducted in high fluoride belt area of state Punjab in India, with the fluoride content in drinking water %3E;1.5 ppm.⁵

Dental fluorosis, if nonpitted, appears clinically as initial white spot lesion areas. This may range from narrow to pronounced opaque white lines following perikymata to irregularly shaped chalky white to cloudy opacities over the tooth surface. This appearance till grade IV of the Thylstrup Fejerskov index of dental fluorosis occurs due to change in the refractive index of the subsurface hypomineralized porous enamel with respect to the intact hypermineralized surface layer.^6,7 Various minimally invasive suggested treatment modalities for esthetic treatment of such defects are microabrasion, tooth whitening procedures with bleaching agents, along with invasive procedures such as composite restorations and veneers. Microabrasion and composite veneering procedures require removal of the surface layer of the enamel. Also patients with composite veneers always report either with dislodgement of the composite layer or its discoloration with passage of time. Further, microabrasion and bleaching procedures pose problems of postoperative sensitivity, long-term follow-up, and young patient compliance.^8,9

Combating all these problems, the resin infiltration concept was introduced in the literature as therapeutic treatment of white spot lesions due to incipient caries and postorthodontic decalcifications. This is claimed to be a young patient-friendly, minimally invasive, definitive, and corrective therapy with a low-viscosity resin having a high penetration coefficient for nonpitted white spot lesions in newly erupted permanent incisors in young children. It works by occluding subsurface microporosities, thereby reversing healthy enamel color and translucency.^8–10

Hence, the present study was planned with the aim to analyze the masking potential of resin infiltration with dental milestones guaranteed caries infiltration concept (DMG ICON) on nonpitted white spot lesions due to fluorosis in the esthetic zone with the goal of improving self-confidence and psychological development in these children.

MATERIALS AND METHODS

This clinical controlled prospective interventional study was conducted in the Department of Pediatrics and Preventive Dentistry, Dasmesh Institute of Research and Dental Sciences, Faridkot, Punjab, India (district Faridkot of state Punjab, which is an endemic area of fluoride in northern India), with the fluoride content in drinking water >1.5 ppm.⁵

RESULTS

As per the described standardized photographic technique in the methodology, both pretreatment and posttreatment photographs of each tooth sample were transferred and projected to the grid of the image-analyzing software, i.e., Adobe Photoshop Software 7.0 (Adobe Systems, San Jose, California) in the computer.^8,15

In this grid, the specific point on the divided tooth part of the sound enamel was chosen to record most accurate values of La*b* coordinators of tooth color, which were kept constant pre and postoperatively, whereas L₁a₁*b₁* were designated to preoperative coordinators of tooth color for the selected site of lesion area. For each tooth sample, preoperative ΔE₁ was calculated using the CIE L*a*b* color space formula equation ΔE = (ΔL² + Δa² + Δb²)^½. Preoperative coordinators of tooth color for lesion area, i.e., L₁a₁*b₁* and calculated ΔE₁ values (Table 1) of 60 tooth samples were taken as control. Similarly, after resin infiltration, postoperative coordinators of tooth color for lesion area, i.e., L₂a₂*b₂*, were obtained using the image-analyzing software and postoperative ΔE₂ values (Table 1) were calculated using the above equation (where L*a*b* coordinators of tooth color for the sound tooth enamel were kept constant).

As shown in (Table 2), pretreatment ΔE₁ values (control) were found in the range from 3.46 to 14.49 with mean 8.226 ± 3.034 and posttreatment ΔE₂ values ranged from 1.33 to 12.84 with mean 5.641 ± 2.644. The net ΔE value was calculated for each tooth sample by calculating difference of postoperative ΔE₂ and preoperative ΔE₁ (ΔE₂–ΔE₁) for 60 tooth samples (Table 1). Postoperatively to resin infiltration, 85% study tooth samples (n = 51) showed complete masking of white spot lesions of fluorosis esthetically with net ΔE values less than or equal to 3.7, whereas lesions in 15% tooth samples (n = 9) had incomplete masking with net ΔE > 3.7 (i.e., net ΔE = 3.7–5 in n = 5, net ΔE = 5–7 in n = 1 and net ΔE > 7 in n = 3), as shown in (Table 1 and Fig. 5), where net ΔE values were found to be in range of 0.15–8.27 with mean 2.584 ± 1.772 (Table 2). These data were analyzed statistically with the Statistical Analysis Software SPSS (Statistical Package for Social Sciences by Armonk, New York) using the “Wilcoxon signed-ranks test,” which showed p value %3C; 0.001, i.e., highly significant (Table 2). Clinically, stability of esthetically masked lesions in these tooth samples was found to be up to patient satisfaction at 1-year follow-up (Figs 1A, 2A, 3A, 4A).

DISCUSSION

Fluorotic white spot lesions on the labial surface of newly erupted permanent anterior teeth pose an obvious esthetic and psychological challenge in growing children. The esthetic management of these lesions without transforming the original form of the tooth could be a challenge for pediatric dentists. The perception of tooth color to the naked eye is the outcome of transmitted incident light after its absorption through mineralized dental hard tissues and subsequent scattering from the tooth surface.¹⁶ Clinical presentation of mild fluorosis as nonpitted white spot lesions on newly erupted permanent incisors occurs due to change in the refractive index of the enamel in lesion area (1.33) with respect to the sound enamel of the affected tooth (1.66).^8,9,20

The resin infiltration technique with DMG ICON works on the principle of the “Chameleon effect” by occluding subsurface micropores in hypomineralized fluorosed lesions after curing of the infiltrated low-viscosity resin having a refractive index comparable to that of the enamel (1.52), which achieves required blending of the masked lesion with the sound enamel.^8,9,20 Additionally, the resin infiltrate has low contact angle, high surface tension, and high coefficient of penetration to complete lesion depth favoring its flow by capillary-driven forces into subsurface microporosities leading to the required refractive index for effective masking.²¹

In this study, the masking of 60 tooth samples with fluoridic white spot lesions in the esthetic zone (as per the inclusion criteria) was done by the resin infiltration technique with DMG Icon. Clinically, selection of tooth samples for resin infiltration in the present study was attempted in accordance to the TF index of dental fluorosis.¹⁰ It is more sensitive than the Dean’s index to provide elaborated clinical presentation of various grades of dental fluorosis (especially in endemic areas) in correlation with histological aspects of the affected enamel, further increasing its validity and reliability.⁷ Various studies have shown that the image-analyzing software analyzing standardized clinical photography is more objective and reliable in quantifying lesion color and size. Even spectrophotometers and colorimeters are sensitive to measure tooth color change, but colorimeters are less accurate than spectrophotometers because they have significant edge loss, which leads to error in color measurement with variation in inter instrument reliability.¹⁵ Hence by the application of color science in dentistry, we can analyze the minimal noticeable change in tooth color using colorimeters, spectrophotometers, and image-analyzing softwares for in vivo studies.^15,16 All these techniques can evaluate minimal noticeable color change to the human eye by obtaining Euclidean distance, i.e., ΔE (Delta E), from the CIELAB color space formula using equation ΔE = (ΔL² + Δa²+ Δb²)^½, where coordinators of physical intensity of color have perceptual meaning, i.e., L* (lightness/darkness), a* (green–red), and b* (blue–yellow).^16–18

Keeping in mind the basis of the resin infiltration concept as a noninvasive procedure, following strict manufacturer’s instructions neither we have repeated the etching step for complete removal of the surface layer for its complete erosion nor we have increased etching and application time of Icon infiltrant. Although few percentages of tooth samples (15%) in this study showed inappropriate results postoperatively, yet 85% of study samples have shown successful masking of lesions esthetically with highly significant results statistically (p value < 0.001). High patient satisfaction in terms of esthetic stability of masked lesions in these tooth samples was observed clinically at 1-year follow-up (Figs 1A, 2A, 3A, 4A), which has predicted resin infiltration as single-sitting, quick, noninvasive, painless treatment of these lesions while maintaining shape, size, form, and function of the sound tooth structure without its additional loss in an economical manner than conventional approaches without relapse of treated lesions.

DMG ICON used in present study contains 15% HCl (rather than 37%) as Icon etch to erode the surface hypermineralized layer for exposure of subsurface microporosities. Thereby, in accordance to the modern era of minimally invasive dentistry, Icon etch removes only about 40 μm of the surface layer, whereas initial tooth reduction in microabrasion removes about 360 μm of the surface enamel. Following this step, neither cavitation occurred nor any manual tooth reduction is required in contrast to composite restorations or veneers and microabrasion.^8,9,21,22

Further complete desiccation was achieved by application of Icon dry containing 99% ethanol for 30 seconds to remove water filled in exposed micropores of the etched surface of the lesion to facilitate the diffusion of Icon Infiltrant, i.e., the low-viscosity resin into the lesion body to occlude subsurface microporosities.^8–10 In comparison to this fact, bleaching techniques treat only superficial layers of the enamel, not from inside of the complete lesion body, therefore their results are dramatic, inconsistent, and time-consuming.^9,23

In this clinical control trial prospective interventional study, 51 tooth samples (85%) showed complete masking of white spot lesions of fluorosis postoperatively to resin infiltration with net ΔE values less than or equal to 3.7, whereas these lesions in nine tooth samples (15%) were not masked completely with net ΔE %3E; 3.7 (Table 1, Fig. 5), which was in accordance with the literature review of the resin infiltration technique. Auschill et al. did esthetic evaluation of mild to moderate fluorosis stains by resin infiltration with DMG ICON in 2015. After follow-up of 6 months, they found resin infiltration to be an agreeable option for these lesions than other invasive, conventional procedures but they emphasized that long-term outcomes of this technique need to be determined by further studies.²⁴ Also Gugnani et al. analyzed esthetic changes in nonpitted fluorosis stains in 2017 by comparative postoperative effects of resin infiltration, in office bleaching and combination therapies. They reported that resin infiltration alone or in combination with bleaching therapy showed better results than bleaching therapy alone in these defects.¹⁰ In 2018, Di Giovanni et al. did a systemic review of interventions for dental fluorosis in six clinical trials and they found highest percentage of success in esthetic improvement with resin infiltration technique alone or its combination with bleaching therapy followed by bleaching alone, which was least with microabrasion.²³ Theodory et al. in 2019 conducted an in vitro study to compare the masking ability and penetration capacity amongst three resin composite sealers i.e., Biscover LV (Bisco), Optiguard (Kerr Hawe), Permaseal (Ultradent and resin infiltrant i.e., DMG ICON with control group as no treatment. Procedures were done in shallow artificial caries lesions of seventy five extracted human molars. They concluded that resin infiltrant DMG ICON showed the deepest penetration of all resins on analysis of clinical photographs based on 100-mm visual analogue scale (VAS).²⁵ Further long-term camouflage effects of resin infiltration (Icon, DMG, Hamburg, Germany) was reassessed by Knosel et al. in an in vivo study of 20 subjects. They found that assimilation of the infiltrated white spot lesion to the color of the sound adjacent enamel by resin infiltration was suitable for the long-term improvement in the esthetic appearance of postorthodontic white spot lesions.²⁶ Also Garg and Chavda managed three cases of mild to moderate fluorosis by combination of bleaching and the resin infiltration technique followed by quantification of color change using the Adobe photoshop software using the CIEDE2000 formula and they achieved satisfactory masking of these lesions, which was stable till 12 months of follow-up.²⁷

Hence, our results advise the use of the resin infiltration technique to successfully mask white spot lesions of dental fluorosis ranging from grade I to IV of the TF index with stable esthetic masking of these lesions at 1-year follow-up. This child-friendly technique aid in developing a better psychology in growing children.

CONCLUSION

The minimally invasive resin Infiltration technique using DMG ICON is highly efficient in masking nonpitted white spot lesions of dental fluorosis in newly erupted permanent central incisors, which enhances the esthetics, self-confidence, and psychological well-being in children.

CLINICAL SIGNIFICANCE

The outcome of masked and blended white spot lesions of fluorosis with the sound enamel in the smile zone with the resin infiltration technique was found to be a child-friendly, noninvasive, single-sitting approach with stabilized results in follow-up visits.

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