A tax deduction that remains applicable to this day (from TurboTax, http://turbotax.intuit.com):
Does Your Child Have an Overbite?
If so, you might want to enroll them in clarinet lessons. Both the clarinet and music lessons are tax deductible thanks to a 1962 provision added after orthodontists argued that playing the clarinet helps with a child's overbite and thus may qualify as a medical expense.
The IRS ruling (Rev. Rul. 62-210, 1962-2 C.B. 89, text from www.charitableplanning.com):
The taxpayer's son has a congenital defect which results in a severe malocclusion of his teeth. An orthodontist recommended that the child take lessons in playing a clarinet, as he considered continued practice with this instrument therapeutic treatment towards alleviating the specific condition. Held, an amount which does not exceed the minimum cost of a clarinet of a quality sufficient to give effect to the therapeutic treatment recommended by the orthodontist and the cost of lessons necessary for the son to play the instrument to the degree required to obtain the benefits of the treatment may qualify as medical expenses within the meaning of section 213 of the Internal Revenue Code of 1954. Such amounts paid are deductible by the taxpayer to the extent provided in that section.