Officers do not need to be sworn, but commissioners or board members do. Perhaps by officers you mean board members, or perhaps your officers are also your board members.

As for what does it mean to be sworn: Statutory road associations are essentially tiny little governments, the formation of which is provide for in Maine's private ways statute. By a majority vote of the property owners benefitted by a common way, a governing authority is created, whose jurisdiction includes all of the benefitted properties (including those who voted against formation of an association). The power of that association is very narrow -- the maintenance of a road -- but it has the power to levy monetary assessments, and to compel payment.  

The law has a seemingly circular passage: "The commissioner or board chosen under section 3101, with respect to the private road, private way or bridge, has the powers of a road commissioner" (23 MRSA 3102). A commissioner has the powers of a commissioner?  What it means is the the commissioner (or board) elected by the members of a road association constituted under the private ways statute has the same powers as a municipal road commissioner.  And that's where the "to be sworn" comes in.

Municipal road commissioners are public officers who are invested with certain powers under the law.  Like any public official, they are required to take an oath of office before assuming the powers of that office.

A commissioner (or board) elected by a statutory road association is more or less the same thing in minature: an official granted certain powers under the laws of the State of Maine. And the statute requires them to be sworn, the same as a public official.

The following is the oath of office required by the Constitution of the State of Maine:

I, (name) do swear, that I will support the Constitution of the United States and of this State, so long as I shall continue a citizen thereof. So help me God.

I (name) do swear, that I will faithfully discharge, to the best of my abilities, the duties incumbent on me as (office) according to the Constitution and laws of the State. So help me God.

An affirmation may be administered to those who choose not to swear an oath.  The oath or affirmation may be administered by any officer empowered to administer oaths, such as a town clerk, notary public or dedimus justice.

As a matter of interest, there are six Road Commissioners near where I live. I am the only one who has taken the trouble to be sworn. When I was first elected six years ago I remained unsworn for two years. Since we are both a statutory road association and a nonprofit corporation we have a "corporation" clerk who is an attorney. I inquired of him whether or not I shoud be sworn and he said my election constituted being sworn. I was not confident with his reponse so I went to the town office where the town clerk (a notary) assisted in preparing a document and swearing me. (It did cost $5.00.) Since then I have been sworn at no cost by a notary at the bank where our association has a checking account. Banks will generally do this if you are a customer. I feel that being sworn makes us "more" legal and worry that a shrewd attorney might say that any Notices of Claim (previously Liens) are not enforceable if I am not sworn. Of course if that happened I would simply re-record after being sworn.

I also agree with you that Mr.Todd Tolhurst provides great answers to many questions and confusing situations. We are fortunate that he is a member of MARA. 

Good luck with your association.