Essentially, the balance between mineralisation and demineralisation shifts to favour demineralisation of enamel, giving the tooth less resilience in structure, thereby making it vulnerable to caries.The poor structural properties of the enamel in teeth with MIH also increase the likelihood of cavitation of any lesions, thereby causing the lesion to progress at a faster rate. Progression of the carious lesion is also more rapid in teeth with MIH as patients may experience tooth sensitivity while carrying out oral hygiene, causing them to avoid doing so and consequentially accelerating the decay. Hypersensitivity
Teeth affected by MIH are often affected by hypersensitivity due to changes in temperature or toothbrushing. A study has suggested that a possible cause of hypersensitivity in MIH is the inflammatory reactions in the pulp due to oral bacteria penetrating through the hypomineralised enamel into the dentinal tubules. Difficult to anaesthetise
It has been reported that MIH-affected teeth were more difficult to anaesthetise. Difficulty achieving anaesthesia in MIH-affected teeth may be caused by the chronic inflammation of the pulp due to the penetration of bacteria as the presence of inflammation can reduce the efficacy of local anaesthetics  which may then result in more anaesthetic being given to achieve anaesthesia. Some dental treatment has been undertaken without local anaesthesia which could result in a child becoming more fearful and anxious when receiving dental treatment.
Depression
Selegiline is also delivered via a transdermal patch used as a treatment for major depressive disorder. Administration of transdermal selegiline bypasses hepatic first pass metabolism. This avoids inhibition of gastrointestinal and hepatic MAO-A activity, which would result in an increase of food-borne tyramine in the blood and possible related adverse effects, while allowing for a sufficient amount of selegiline to reach the brain for an antidepressant effect.A quantitative review published in 2015 found that for the pooled results of the pivotal trials, the number needed to treat (a sign of effect size, so a low number is better) for the patch for symptom reduction was 11, and for remission, was 9. The number needed to harm (inverse of the NNT, a high number here is better) ranged from 387 for sexual side effects to 7 for application site reaction. With regard to the likelihood to be helped or harmed (LHH), the analysis showed that the selegiline patch was 3.6 times as likely to lead to a remission vs. a discontinuation due to side effects; the LHH for remission vs. incidence of insomnia was 2.1; the LHH for remission vs. discontinuation due to insomnia was 32.7. The LHH for remission vs. insomnia and sexual dysfunction were both very low. Special populations
For all human uses and all forms, selegiline is pregnancy category C: studies in pregnant lab animals have shown adverse effects on the fetus but there are no adequate studies in humans.