By Emma Yasinski
Since the late 1970s, dentists and researchers alike have observed, with growing frequency, a condition that can readily be confused with a variety of enamel disturbances; yet this condition is distinct.
Formally defined in 2001 as Molar Incisor Hypomineralization, MIH continues to befuddle those trying to determine its causes and prevalence. That said, there is a broadening consensus that too many cases are going undiagnosed, leading to an array of clinical errors.
German dental expert Falk Schwendicke, among the latest researchers to attempt to decode the enigma of MIH, believes it is a near certainty that every pediatric dentist reading this article will have “MIH in their practice, and they might not even know or detect it because they are not looking for it.”
Dr. Schwendicke, PhD, Dr med dent MDPH, Deputy Chair of Operative and Preventive Dentistry at the Universitätsmedizin Berlin, spoke with Incisor by phone from Berlin. He is the lead author of a January 2018 study on the topic, Global burden of molar incisor hypomineralization, published in The Journal of Dentistry.
MIH is a developmental issue that is highly prevalent throughout the world, and by some estimates may affect up to a fifth of all children globally. The United States has some of the highest worldwide rates of both newly diagnosed and previously diagnosed cases of MIH, according to Dr. Schwendicke’s study.
No known cause
MIH is characterized by enamel defects in the first permanent incisors and molars. Identified by discolored patches of soft, crumbly enamel, MIH creates sharply bordered lesions on cusps of the teeth where caries are unlikely to be found. MIH-affected teeth are typically very sensitive, and hence can make even the simple act of eating painful.
The severity of MIH may vary greatly according to a study by Dr. Garg Nishita and colleagues in the International Journal of Pediatric Dentistry (IJPD). It ranges from mild opacities to posteruptive breakdown. Additionally, MIH can be masked by extensive caries or restorations.
The exact cause of MIH is unknown, and for now, there is nothing that can prevent the condition.
The Australasian Academy of Paediatric Dentistry (AAPD) notes that children whose teeth are affected by MIH "can require ten times as much dental treatment as unaffected children." Although poor diet and lack of brushing do not cause MIH, improvements in a child's diet and overall oral hygiene can help prevent further deterioration, AAPD says.
Patients with MIH are more likely than others to go on to develop caries, making it especially important to recognize and treat early in order prevent hypersensitivity and the future formation of caries.
Previous studies attempting to quantify the global burden of MIH have shown inconsistent results. Dr. Schwendicke and his team sought not only to count the number of MIH cases, but also to see if they could identify environmental and other risk factors associated with developing the disease.
They analyzed 99 studies from 43 different countries, including more than 110,000 different cases. The team found a mean global prevalence of 13.1%, with significant differences between countries, regions, and super-regions (larger areas that include several regions, sometimes spanning continents.)
India, Pakistan, and Indonesia had the highest numbers of newly diagnosed cases.
Dr. Schwendicke and his team also analyzed data in terms of socioeconomic and environmental variables in an effort to identify risk factors associated with MIH, but the results yielded few answers. The data seemed to suggest that lower and middle-income areas had more cases of MIH, but Dr. Schwendicke explained that this is likely because these regions and super-regions had more people, and more young people, and was unlikely to be directly related to income.
"What we had hoped, originally, was that we would see some sense-making associations," said Schwendicke, "Let's say, temperature, or environmental pollution, or antibiotic use, or some kind of association with all these factors, which we know could be important, but we didn't find it."
Early identification and treatment
It is too early to tell, he explained, whether such associations with MIH don't exist, or if they were hidden by the inconsistencies and biases of the studies his team analyzed.
Moving forward, Dr. Schwendicke says, others will need to take on the challenge of elucidating the epidemiology of MIH. He plans to shift his focus back to his patients; beginning a randomized controlled trial of different management strategies for MIH.
AAPD says that when it comes to treating MIH, the best results are obtained when the condition is identified at the onset. "Treatment options may include symptom control, interim stabilization, restoration, or a carefully-timed extraction of the affected tooth or teeth."
Dr. Nishita, writing in IJPD, believes the optimum age for dentists to examine children for signs of MIH is 8 years old, when all permanent first molars and most of the incisors are erupted.
One particularly interesting characteristic of MIH, according to AAPD, is that the affected teeth do not respond normally to local anesthetic and "it is common for children to experience breakthrough pain during treatment even when the whole area seems to be very numb."
Falk Schwendicke, Karim Elhennawy, Seif Reda, Katrin Bekes, David J Manton, Joachim Krois Global burden of molar incisor hypomineralization Journal of Dentistry 2018, Volume 68, pp 10-18
Garg N, Jain AK, Saha S, Singh J. Essentiality of Early Diagnosis of Molar Incisor Hypomineralization in Children and Review of its Clinical Presentation, Etiology and Management. Int J Clin Pediatr Dent 2012;5(3):190-196.
Jälevik B. Prevalence and Diagnosis of Molar-Incisor-Hypomineralisation (MIH); A systematic review European Archives of Paediatric Dentistry 2010, Volume 11, Issue 2, pp 59-64
Wonky teeth - Molar Hypomineralisation - Australasian Academy of Paediatric Dentistry, June 17, 2016
Author: Contributing writer Emma Yasinski received her Master of Science (MS) in science and medical journalism from Boston University. Her articles have also appeared at TheAtlantic.com, Kaiser Health News, NPR Shots, and Genetic Engineering and Biotechnology News.
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