What Are the Causes of Dental Fluorosis?
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Dental fluorosis is caused mainly by the excessive ingestion of fluoride that occurs during the crucial phase of tooth development in children. Fluorosis of the enamel has a marked impact usually throughout life. The changes in the enamel of the tooth of an infected individual are visually quite detectable. These enamel changes characteristic of dental fluorosis are linked to water fluoride levels above the range of 1.5 ppm (parts per million).
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Usually, artificially fluoridated water has a target fluoride concentration of only around one part per million (ppm). Fluoridation in water (community water fluoridation is a public initiative in most countries) is done to promote the anti-cariogenic properties of fluoride, which help reduce the risk of dental caries in children and young adults by promoting enamel remineralization.
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Dental fluorosis can target both genders equally and can occur in both primary and permanent dentition as well. Though the exact pathophysiology of dental fluorosis is not understood; however, it is assumed that the severity of dental fluorosis is not only dose-dependent but is primarily influenced by the extent of time the child is exposed to the concentration or excessive fluoride level. It is further influenced by developmental and genetic factors that vary from individual to individual.
What Is the Critical Window and Global Statistics?
The critical window for dental fluorosis to develop in response to excessive fluoride concentration exposure usually ranges in the period between birth to around eight years of age. As per the research, excessive consumption of fluoride outside this critical window age period is not known to usually cause dental fluorosis. The excessive plasma fluoride levels affect individuals and interfere with the removal of proteins called amelogenins during the enamel maturation phase. This leads to the formation of hypomineralized (less mineralized) enamel tissue of the tooth.
The worldwide prevalence of dental fluorosis is on the rise according to current statistics. In the United States, nearly 23 percent of the total population is known to be affected by some form of dental fluorosis. In adolescents, this figure has almost doubled since 1987 to a whopping 41 percent. This is a significant increase in the prevalence of mild to moderate cases of dental fluorosis. Hence, according to the United States Department of Health, the target concentration in fluoridated water has been reduced over the last decade from one part per million (ppm) to only 0.7 ppm.
What Is the Pathophysiology of Dental Fluorosis?
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Ameloblast cells which are responsible for enamel synthesis during the process of amelogenesis, a regulated process in which hydroxyapatite crystals of enamel are produced, are affected by the high fluoride ion concentration. The exposure to these high plasma fluoride levels during this phase is what results in the formation of porous enamel which is weaker and hypomineralized.
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The additional complication that can occur during the maturation phase is when the enamel matrix proteins, such as amelogenin are hydrolyzed by the enzymes called proteinases. This process is delayed in individuals with dental fluorosis. The fluorosed enamel further shows enamel pitting commonly because of interference even in the maturation phase.
What Are the Clinical Features of Dental Fluorosis?
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Clinically the severity of dental fluorosis ranges from almost no undetectable surface-level enamel changes (characteristic of very mild fluorosis) to severe forms of pitted enamel that have become stained as a dark yellow-brown portion of the enamel in the tooth crown.
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Most patients with mild fluorosis may not usually notice the opaque whitish flecks that are scattered insignificantly through the enamel of the tooth crown. However, individuals who suffer from moderate to severe fluorosis form report to the dentist their aesthetic concerns that bring attention to the evident discoloration or pitting of the teeth affected.
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In mild and moderate cases, the light enamel opacities are of only aesthetic concern. However, the difference with severe cases is that there may be even a structural compromise because the enamel is hypoplastic (underdeveloped) and weak with a lower aggregation of hydroxyapatite (naturally occurring) crystals of calcium that make up the tooth enamel. It is not uncommon for severe fluorosis cases to even report or suffer from dentine hypersensitivity (sharp or shooting pain due to dentine exposure) that may aggravate with time.
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The dentist is usually careful during physical examination of the pitted surface enamel in severe fluorosis because even a dental probe if not used cautiously or carefully can damage the already compromised tooth structure.
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For patients suffering from dental fluorosis, it would be surprising to know that even routine dental investigations like radiographic imaging or dental sensibility testing (to determine the pulp sensibility or health of dental pulp nerves) would not be of much use as it is an acquired damage to the superficial tooth enamel. Dentists should primarily address the functional concerns of these patients, if any, regarding the affected teeth and focus on the aesthetic as well.
How Is Dental Fluorosis Managed?
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In mild cases of dental fluorosis, vital dental bleaching is considered a good strategy and a highly effective treatment modality. The concentration of hydrogen peroxide used for vital bleaching may vary depending on the permissibility for dental whitening purposes.
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Lightening the color of the healthy, unaffected tooth structure would help camouflage to an extent the lighter fluoresced or hypomineralized enamel, resulting in a more aesthetic appearance.
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With the advent of modern-day dentistry, other minimally invasive techniques have been made available for treating mild to moderate cases such as enamel microabrasion procedures. The enamel microabrasion involves the mechanical removal of the superficial layers of fluoresced enamel reducing the visibility of enamel discoloration. This method; however, can have limited efficacy or be at a disadvantage when used for treating deeper or severely discolored teeth.
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In fluorosis cases with severe discoloration, the best option suggested by the dentist usually is either veneers or conventional crowns. These are necessary to achieve a cosmetically acceptable outcome. Crowns are considered the most viable and long-term restorative options to mask the insufficient or poor-quality enamel as compared to only composite restorations, which rely usually on effective enamel-resin bonding for retention.
Conclusion
Due to the exposure to increased fluoride levels in early childhood, the primary concern for most patients affected by dental fluorosis is aesthetics because of the discoloration that would be mild, moderate, or severe. These patients would need lifelong functional maintenance by the dentist of their restorations or crowns apart from sustaining the esthetic outcomes. Therefore, it is imperative for this reason that dental restorative treatment plans should be focused upon the principles of minimally invasive dentistry, and also instructions or preventive measures should be given by the dentist regarding supervised toothbrushing in children, encouraging children not to ingest dentifrices easily, limiting the use of additional fluoride supplements in areas already infiltrated by high concentration fluoridated water.
