Treatment of post-orthodontic white spot lesions by resin infiltration: a case series

INTRODUCTION

White spot lesions (WSLs) are the most common side effect of fixed appliances [1], which concern at least three teeth in 77% of orthodontic patients [2], and can seriously jeopardize the esthetic outcome of the treatment [3].
The prevalence of WSLs is reported to vary from 2% to 96%. Their prevalence in patients not undergoing orthodontic treatment is about 24%, which rises to 50% in those who underwent orthodontic therapy. These variations largely depend on the methods used for detection of WSLs, as well as on patient’s compliance with the recommended preventive measures [2, 3].
The presence of enamel discolorations on the esthetically exposed teeth affects patient’s quality of life [4, 5]. Clinically WSLs appear as an incipient non-cavitated carious lesion, with a chalky white, mat, opaque halo around the bracket position [1]. The white appearance of WSLs is caused by enamel demineralization, under a hyper-mineralized intact outer enamel layer of about 10 to 30 mm, while in the porous subsurface layer organic fluids replace the diminished interprismatic mine¬ral phase [6]. As light refraction through enamel is directly related to the level of mineralization, the presence of multiple hydroxyapatite/organic fluid interfaces causes the deviation and deflection of incident light, thus causing WSLs to be perceived as white defects [2]. Light refraction determines the refractive index (RI) amount. Sound enamel presents a RI of 1.62, while WSLs’ refractive index can vary from 1 to 1.33, depending on whether the enamel surface is dried or hydrated.
Treatment with resin infiltration has been recently developed by the dentistry equipe at Charité University of Berlin, Germany and was first proposed to halt the interproximal early stage non-cavitated caries lesions [7, 8]. The treatment has been subsequently extended to hypo¬mineralized lesions on the vestibular enamel surface. Paris et al. [9] noted that lesions infiltrated by Icon took on the appearance of the surrounding sound enamel, masking the whitish appearance by filling the lesion’s body with resin, which results in a rise of the RI of the lesion [10, 11].

MATERIAL AND METHODS

Over 30 patients were treated with Icon from November 2014 to November 2016 by our group at the First Operative Unit, Sapienza University (Rome, Italy). Here we present four postorthodontic patients with WSLs, who underwent Icon resin infiltration treatment.

ICON PROCEDURE

Tooth surfaces were cleaned with a rubber cup and prophylaxis paste, before placing the rubber dam. Icon-Etch (DMG, Hamburg, Germany) 15% hydrochloric acid gel was then applied for two minutes for a maximum of three times. Then the etching gel was washed away thoroughly for 30 seconds using a water spray and then dried with air spray.
The lesions were desiccated using ethanol (Icon-Dry; DMG) for 30 seconds followed by air drying (Figures 1-4).
After desiccation, the infiltrant low viscosity resin (Icon-Infiltrant; DMG) was applied on the surface and allowed to penetrate for three minutes. The excessive material was then removed using air spray from the vestibular surface and using dental floss from the proximal spaces before light curing, which was applied for 40 seconds. The application of resin was then repeated another time before polishing of the roughened enamel surface using a rubber point and finishing strips (Figures 5-7).

CASE REPORTS

Patient 1 is a 22-year-old female, who asked for cosmetic treatment of multiple anterior WSLs on the upper six teeth, due to orthodontic fixed appliances (Figures 8 and 9). Patient 2 is a 17-year-old female who presented with small WSLs on upper lateral incisors and premolars, discovered after orthodontic debonding (Figures 10-12). Patient 3 is a 20-year-old female with slight WSLs on upper incisors after orthodontic therapy (Figures 13 and 14). Patient 4 is a 23-year-old female who presented requesting laminate veneers to hide WSLs due to orthodontic fixed appliance and pre-existing mild fluorosis (Figures 15-19).

RESULTS OF ICON TREATMENT

In all patients, existing WSLs were successfully treated by Icon resin application. Illustrative cases are shown in Figures 20 to 31. Given the minimal substance loss due to the erosion infiltration procedure, all patients were extremely satisfied with the results, although some WSLs could still be seen.

DISCUSSION

We, herein, presented four young patients with post-orthodontic WSLs on the labial surface of aesthetically relevant teeth, who were treated using Icon infiltrative resin with restoration of the defects that took on the appearance of the surrounding sound enamel.
White spot lesions, which are classified as non-cavi¬tated carious lesions, are the most common and unpleasant side effects of orthodontic fixed therapy, most frequently found in patients with concomitant poor oral hygiene and low compliance with the advocated preventive measures. Like other enamel hypomineralization defects, WSLs can seriously jeopardize the esthetic outcome of orthodontic treatments.
Recently, Icon treatment has been proposed as a therapy that can halt carious progression and mask the whitish halo typically found in WSLs. Icon treatment has changed dentistry’s approach to the management of hypomineralized enamel lesions. Until recently, crowns, laminate veneers, restorations and micro-abrasion have been used to treat teeth presenting with tooth color abnormalities [12, 13]. Tooth preparations for the above-mentioned therapies require removal of enamel extending to the demineralized zone and in some cases penetration into dentin [14]. On the other hand, none of the existing treatments such as fluoride and casein phosphopeptide provide a certain esthetic outcome [15]. By contrast, resin infiltration requires no mechanical enamel removal, as it erodes approximately 40 µm of the outer enamel layer to expose the lesion [7]. This technique leads to a good, real and fast improvement in labial tooth surface appearance [7, 16]. Because orthodontic WSLs predominantly affect the young patient population, long-term prognosis of the restored teeth is a significant concern and a less invasive restorative technique is preferable [17].
We performed Icon resin infiltration treatment in four young patients presenting with post-orthodontic WSLs on the upper and lower arch. Etching was repeated up to three times, according to the manufacturer’s instructions. Three of the patients showed a complete esthetic resolution of the enamel color abnormalities. In one case, where a combination of severe fluorosis and WSLs was present, and laminate veneers could be indicated, some of the WSLs were still visible at the end of treatment.
The two main open questions regarding the esthetic outcome of therapy of WSLs are color stability of the treated teeth over time and the capability of predicting patients’ responses based on the underlying etio¬logy of the treated lesions. According to the findings of Denis et al. [2] pathological diagnosis of enamel hypomineralization is a mandatory prerequisite to start Icon treatment. Moreover, when the location of the defect is beyond the enamel layer, greater caution should be advised.
As reported in a recent systematic review of the published literature [3], the follow-up period for color stability of the treated WSLs is usually very short (12 months) and the effect of aging on such restorations is unknown. This suggests the need for studies to assess this parameter during a long-term follow-up.
In conclusion, our case series illustrates the possibility of treating WSLs due to orthodontic treatment with Icon resin infiltration, which can mask tooth color abnormalities. Studies with longer observation periods and involving larger patient populations are needed to validate the clinical significance found in our case series.

CONFLICT OF INTEREST

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

References

1. Srivastava K, Tikku T, Khanna R, Sachan K. Risk factors and mana¬gement of white spot lesions in orthodontics. J Orthod Sci 2013; 2: 43-49.
2. Denis M, Atlan A, Vennat E, et al. White defects on enamel: diagnosis and anatomopathology: two essential factors for proper treatment (part 1). Int Orthod 2013; 11: 139-165.
3. Sonesson M, Bergstrand F, Gizani S, Twetman S. Management of post-orthodontic white spot lesions: an updated systematic review. Eur J Orthod 2017; 39: 116-121.
4. Chankanka O, Levy S, Warren J, Chalmers J. A literature review of aesthetic perceptions of dental fluorosis and relationships with psychosocial aspects/oral health-related quality of life. Community Dent Oral Epidemiol 2010; 38: 97-109.
5. Tirlet G, Chabouis HF, Attal JP. Infiltration, a new therapy for masking enamel white spots: a 19-month follow-up case series. Eur J Esthet Dent 2013; 8: 180-190.
6. Arends J, Christoffersen J. The nature of early caries lesions in enamel. J Dent Res 1986; 65: 2-11.
7. Paris S, Meyer-Lueckel H, Mueller J, et al. Progression of sealed initial bovine enamel lesions under demineralizing conditions in vitro. Caries Res 2006; 40: 124-129.
8. Paris S, Meyer-Lueckel H, Kielbassa A. Resin infiltration of natural caries lesions. J Dent Res 2007; 86: 662-666.
9. Paris S, Meyer-Lueckel H. Masking of labial enamel white spot lesions with resin infiltration – a clinical report. Quintessence Int 2009; 40: 713-718.
10. Kim S, Kim E, Jeong T, Kim J. The evaluation of resin infiltration for masking labial enamel white spot lesions. Int J Pediat Dent 2011; 31: 241-248.
11. Paris S, Keltsch J, Dorfer C, Meyer-Luckel H. Visual assimilation of artifical enamel lesions by infiltration in vitro. Caries Res 2010; 44: 171-248.
12. Seow W, Ford D, Kazoullis S, et al. Comparison of enamel defects in the primary and permanent dentitions of children from a low-fluoride District in Australia. Pediatr Dent 2011; 33: 207-212.
13. Jälevik B, Klingberg G. Dental treatment, dental fear and behaviour management problems in children with severe enamel hypomineralization of their permanent first molars. Int J Paediatr Dent 2002; 12: 24-32.
14. Summitt J, Robbins J, Hilton T, et al. Fundamentals of operative dentistry: a contemporary approach. Quintessence 2006; pp. 455-506.
15. Paris S, Schwendicke F, Keltsch J, et al. Masking of white spot lesions by resin infiltration in vitro. J Dent 2013; 41 Suppl 5: e28-e34.
16. Mazur M, Westland S, Guerra F, et al. Objective and subjective aesthetic performance of icon® treatment for enamel hypomineralization lesions in young adolescents: a retrospective single center study. J Dent 2018; 68: 104-108.
17. Senestraro S, Crowe J, Wang M, et al. Minimally invasive resin infiltration of arrested white-spot lesions: a randomized clinical trial. J Am Dent Assoc 2013; 144: 997-1005.
18. Paris S, Meyer-Lueckel H. Resin infiltration after enamel etching. In Tooth Whitening 2016; pp. 211-222.
19. Paris S, Hopfenmuller W, Meyer-Lueckel H. Resin infiltration of caries lesions: an efficacy randomized trial. J Dent Res 2010; 89: 823-826.
20. Martignon S, Tellez M, Santamaria R, et al. Sealing distal proximal caries lesions in first primary molars: efficacy after 2.5 years. Caries Res 2010; 44: 562-570.