In Maine, and in the 2016 tax year, a taxpayer is otherwise eligible to deduct up to $10,000 of their taxable (federal) pension income from taxation by Maine. That is, as much as $10,000 annually of your pension income (as reported and taxed on your federal tax return) can escape being taxed by Maine. If you are married, then you spouse can have an additional, but separate, $10,000 pension income exclusion as well.
Public pensions sponsored by the state of Maine have some further restrictions placed on them, as far as this state-specific deduction is concerned, and that includes teacher pensions. However, the restrictions are not particularly difficult, and they are well-explained in the TurboTax program.
In response to this question, and as a visual guide to data entry, I've also generated a series of screen-capture images from the TurboTax Maine module, based on a hypothetical "John Doe" taxpayer return, over the age of 65, and collecting a public pension in Maine. You can view these images directly below this text; simply click on the icons to open.
That said, there is nothing in Maine state law (or in the TurboTax software) that should prevent you from taking a pension deduction, as long as you are otherwise qualified to do so, based on your income and past service as a teacher.
Thank you for asking this important question.