White Spot Lesions in Orthodontic patients: A Literature Review on Etiology, Incidence, Prevention, and Treatment

Author: Karolina Kontou

Introduction

Orthodontic treatment is widely recognized as a transformative branch of dentistry, offering profound functional, esthetic, and psychosocial benefits. Correcting malocclusions, achieving ideal occlusal relationships, and enhancing dental alignment not only contribute to improved masticatory efficiency, speech, and periodontal health but also enhance patient self-esteem and social confidence. The popularity of orthodontic treatment has grown substantially over the past decades, particularly among adolescents and young adults, reflecting both the increasing demand for cosmetic enhancement and greater awareness of oral health benefits.

However, despite its numerous advantages, fixed orthodontic appliances present challenges for maintaining optimal oral hygiene. Brackets, bands, archwires, and ligatures create plaque-retentive niches that disrupt the natural self-cleaning mechanisms of the oral cavity. The resulting accumulation of dental biofilm establishes an environment conducive to early enamel demineralization.

Among the most frequent and esthetically concerning complications of orthodontic treatment is the development of white spot lesions (WSLs). WSLs are the earliest clinically detectable sign of dental caries, presenting as chalky, opaque areas on smooth enamel surfaces. These lesions arise from subsurface enamel porosities caused by prolonged exposure to acids produced by cariogenic biofilms, predominantly Streptococcus mutans and Lactobacilli. While they may not initially compromise tooth integrity, WSLs have a significant psychosocial and cosmetic impact, especially when localized on anterior teeth. Patients often express frustration when they notice residual white spots immediately after removal of appliances, potentially overshadowing the positive outcomes of orthodontic treatment.

In severe cases, untreated WSLs can progress to cavitated lesions, threatening both function and long-term oral health. The clinical relevance of WSLs has therefore become increasingly recognized, particularly as orthodontic treatment becomes more prevalent worldwide. Early detection, risk assessment, and preventive management are critical to mitigating this complication.

This review synthesizes current evidence regarding the etiology, incidence, risk factors, prevention, and treatment of WSLs, with a particular focus on minimally invasive treatment strategies such as resin infiltration, which represent a paradigm shift in modern caries management. Historical perspectives, patient-centered considerations, and emerging technologies are also discussed to provide a comprehensive overview.

Etiology of White Spot Lesions

Pathophysiology

White spot lesions are defined as subsurface enamel porosities resulting from demineralization of hydroxyapatite crystals beneath an intact enamel surface (Gorelick et al., 1982). Clinically, they manifest as milky white, opaque areas due to altered optical properties of enamel. The increased porosity scatters light differently compared to sound enamel, leading to their characteristic chalky appearance (Paris et al., 2010). The underlying process is governed by a dynamic interplay between demineralization and remineralization. When fermentable carbohydrates are ingested, cariogenic bacteria such as S. mutans and Lactobacilli metabolize sugars into organic acids, primarily lactic acid. These acids diffuse into enamel, lowering the local pH below the critical threshold of approximately 5.5, at which hydroxyapatite crystals begin to dissolve (Richter et al., 2011). While saliva provides calcium, phosphate, and buffering capacity that facilitate remineralization, repeated acid challenges tip the balance toward mineral loss. Over time, this process results in subsurface demineralization beneath an intact surface layer, making lesions reversible in their early stages but potentially progressive if unchecked. An important point to note is that WSLs differ from frank cavitated lesions in that the surface layer remains relatively intact.

Orthodontic-Specific Factors

Orthodontic appliances exacerbate WSL formation through several mechanisms. Plaque stagnation occurs because bracket bases, undercuts, and band margins provide sheltered niches that favor biofilm accumulation. Archwires and ligatures further act as mechanical obstructions, reducing available space and access for toothbrushing and flossing and thereby hindering effective plaque removal. In addition, orthodontic appliances may alter natural salivary flow and buffering, diminishing saliva’s protective function. Finally, because fixed orthodontic treatments often last from 12 to 36 months or longer, teeth are exposed for extended periods to conditions that facilitate demineralization.

Microbiological and Host Factors

Emerging evidence indicates that WSL formation is influenced not only by cariogenic bacteria but also by the overall microbial ecology. Biofilm succession during orthodontic treatment may favor acidogenic species, altering the oral microbiome in ways that prolong cariogenic potential. Host factors, such as enamel composition, salivary protein content, and remineralization capacity, also influence susceptibility. Variations in enamel prism structure and fluoride incorporation can affect how quickly lesions develop under cariogenic conditions.

Incidence and Prevalence

Global Prevalence

The prevalence of WSLs among orthodontic patients remains high. Classic studies (Gorelick et al., 1982) reported post-orthodontic WSL prevalence of 50–70%, highlighting the widespread nature of this complication. More recent meta-analyses suggest a pooled prevalence of approximately 55% and an incidence of about 34% in patients treated with fixed appliances (Hussain et al., 2025). In contrast, individuals not undergoing orthodontic treatment demonstrate a lower prevalence of around 29%, underscoring the additional risk conferred by fixed appliances (Julien et al., 2013). The maxillary anterior teeth, particularly the lateral incisors, are the most commonly affected, mainly due to the difficulty of maintaining hygiene around brackets where the distance between the base of the bracket and the gingival margin is minimal. Posterior teeth exhibit lower incidence rates, likely because of differences in saliva exposure and enamel thickness.

Influence of Appliance Type

Conventional labial brackets are associated with the highest prevalence of WSLs because of greater plaque retention and complex bracket geometry. Evidence regarding self-ligating brackets is mixed, with some studies reporting a slightly reduced incidence of WSLs, while others show negligible differences (Akin et al., 2013). Clear aligners, by contrast, are associated with reduced WSL prevalence, as their removability allows improved access for hygiene and shorter exposure to plaque accumulation (Santonocito et al., 2022).

Age and Demographic Factors

Adolescents are disproportionately affected by WSLs due to both behavioral and biological factors. Compliance with oral hygiene is often suboptimal, and enamel in younger patients may be less mineralized, increasing vulnerability. Gender differences are not consistently reported, but some studies suggest that males may be at slightly higher risk due to lower adherence to oral hygiene routines.

Risk Factors

Patient-Related Factors

Poor oral hygiene remains the most significant predictor of WSLs. Patients with inadequate hygiene practices may be nearly three times more likely to develop lesions. Baseline caries risk also plays a role, with individuals at moderate or high risk being more susceptible (Chapman et al., 2022). Frequent intake of fermentable carbohydrates and acidic beverages accelerates demineralization (Tufekci et al., 2011). Adolescents face an additional disadvantage due to immature enamel and inconsistent compliance with instructions. Salivary characteristics, such as reduced flow or buffering capacity due to systemic illness, medication, or interference by appliances, can further increase susceptibility.

Treatment-Related Factors

Certain treatment variables also contribute to risk. Conventional brackets are associated with higher rates of WSLs compared to self-ligating systems or clear aligners (Hussain et al., 2025). Bracket materials with rougher surfaces or the use of fluoride-free adhesives can promote plaque accumulation. Longer treatment durations, particularly beyond 30 months, have been shown to double the risk of lesion development (Chapman et al., 2022). Operator technique also plays an important role, as precise bonding, minimal adhesive excess, and thorough patient instruction all contribute to reducing risk.

Socioeconomic and Behavioral Factors

Socioeconomic and behavioral determinants cannot be overlooked. Access to professional dental care, patient motivation, level of education, and parental supervision in adolescents all influence WSL incidence. Patients from lower socioeconomic backgrounds may have higher baseline caries risk and limited access to preventive interventions, which further predisposes them to lesions.

Prevention Strategies

Preventing WSLs requires a multifaceted approach that integrates behavioral, chemical, and mechanical strategies. Education is the foundation. Instruction should begin before appliances are placed, continue throughout treatment, and include demonstrations of proper brushing and flossing techniques adapted to orthodontic patients. Tools such as interdental brushes and orthodontic-specific toothbrushes are particularly useful. Modern adjuncts—including reminder applications, gamification strategies, and AI-driven compliance monitoring—have shown promise in reinforcing positive behaviors. Fluoride remains the cornerstone of chemical prevention. High-fluoride toothpaste, containing concentrations of 5,000 ppm or more, has demonstrated superior protective effects compared with standard formulations (Sonesson et al., 2014). Application of fluoride varnishes, particularly 5% sodium fluoride, significantly reduces incidence, with some studies reporting nearly 50% fewer lesions (Zabokova et al., 2014). Fluoride rinses further contribute by enhancing remineralization and reducing biofilm acidogenicity.

Adjunctive remineralizing agents such as casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) have gained popularity. These agents stabilize calcium and phosphate at the enamel surface, promoting remineralization and reducing lesion progression, particularly in high-risk patients (Cochrane et al., 2010). Mechanical barriers offer additional protection. Resin-based sealants and nano-filled coatings applied around brackets act both as physical shields and as fluoride reservoirs, providing dual benefit (Bishara et al., 2008). Appliance design itself influences risk: smaller brackets, self-ligating systems, and especially clear aligners enhance accessibility for cleaning and reduce plaque accumulation. Emerging technologies provide exciting new avenues for prevention. Smart toothbrushes capable of tracking brushing behavior, AI-based monitoring systems that assess hygiene compliance, intraoral scanning for early detection of WSLs, and novel bioactive agents such as probiotic therapies and nano-hydroxyapatite pastes represent the next generation of preventive strategies. Their integration into clinical practice may fundamentally improve outcomes in the coming decade

Minimally Invasive Treatments

When prevention is insufficient, early intervention is key. ICON resin infiltration has emerged as a micro-invasive solution for managing non-cavitated WSLs. The technique involves etching enamel, followed by penetration of a low-viscosity light-curable resin into lesion porosities through capillary action. Once polymerized, the resin occludes diffusion pathways for acids and enhances esthetics by harmonizing the refractive index of the demineralized enamel with that of healthy enamel (Paris et al., 2010). Clinical evidence supports its effectiveness. Knösel et al. (2013) demonstrated that ICON provided durable esthetic improvements that lasted for at least two years. Elrashid et al. (2025) found ICON to be superior to fluoride varnish and micro-abrasion in terms of masking effects, while Hameed et al. (2024) confirmed greater reductions in lesion severity among adolescents treated with ICON compared to fluoride varnish alone.

Compared to other approaches, ICON offers unique advantages. Fluoride and CPP-ACP encourage remineralization but often fail to adequately mask lesions esthetically. Micro-abrasion improves appearance but removes enamel, compromising long-term tooth preservation. Restorative interventions, though sometimes necessary, are invasive, irreversible, and best reserved for cavitated lesions. Resin infiltration therefore represents a middle ground: it is conservative, effective, and patient-pleasing. Further research is needed though to evaluate the long-term effects of ICON resin infiltration and long term benefits as well.

Discussion

WSLs represent a paradox in orthodontics: while orthodontic treatment enhances function and esthetics, it simultaneously predisposes teeth to enamel demineralization. Their high prevalence indicates that oral hygiene instruction alone is insufficient. Effective management requires a prevention-oriented, patient-centered strategy tailored to each individual’s risk profile. Resin infiltration has revolutionized WSL management by providing immediate esthetic improvement while arresting lesion progression. Nevertheless, its limitations—such as cost, technique sensitivity, and the lack of long-term data beyond five years—must be acknowledged.

Future directions include long-term evaluation of ICON outcomes, the development of bioactive infiltrants with antibacterial and remineralizing properties, and the integration of AI and digital tools for early WSL detection and personalized preventive care. Ethical considerations emphasize the importance of informing patients about the risk of WSLs prior to treatment and promoting interdisciplinary collaboration between orthodontists and general dentists.

Conclusions and Recommendations

White spot lesions remain a common and clinically significant complication of orthodontic therapy. Their multifactorial etiology—encompassing microbial, host, mechanical, and behavioral influences—demands proactive and comprehensive management. Preventive strategies centered on patient education, fluoride supplementation, remineralization agents such as CPP-ACP, and protective sealants remain critical. Appliance design should also be optimized to reduce plaque retention. When prevention fails, minimally invasive treatment strategies such as resin infiltration provide highly effective solutions that arrest progression and restore esthetics without sacrificing enamel. Emerging technologies and bioactive materials promise to further enhance both prevention and treatment in the near future. Ultimately, adopting patient-centered, interdisciplinary, and evidence-based approaches will allow clinicians to optimize orthodontic outcomes. By doing so, the dual goals of achieving functional correction and preserving dental health and esthetics can be met, thereby minimizing the burden of WSLs and enhancing patient satisfaction.

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