One of the most critical factors in the success of posterior composites is adequate isolation. Our ability to achieve acceptable bond strengths and prevent marginal breakdown and leakage are dependent on it. Blood and saliva are the enemy during any adhesive procedure. There are numerous options that all allow us to achieve proper isolation. The tried and true is still placing a rubber dam, and even as I type this I know people are cringing at the thought of it. With practice and proper technique rubber dam placement can become easy and efficient. In addition there is also the option of utilizing a split dam technique. In this approach one large slit is created that goes over multiple teeth and is anchored by a clamp on the most posterior tooth and flossed between the anterior abutment teeth.
Another option I use routinely is the Isolite. Whether or not you see benefit in the illumination, the combination of a bite block, tongue and cheek retraction and high volume suction can not be beat. Placement is far easier and quicker than a rubber dam and I find my patients feel less claustrophobic and like that we can take it out from time to time so they can close and relax. Probably the least effective form of isolation is some combination of cotton rolls, dry angles and assistant retraction. It is labor intensive and difficult to manage.
Once we have controlled the tongue, cheek ans saliva flow now we are left with tissue and sulcular fluid. One of the advantages of a rubber dam is that when properly inverted it does all of this localized isolation as well. When using an Isolite or split dam technique local isolation is accomplished with proper matrix band and wedge positioning. Also consider placing a small section of retraction cord interproximally prior to placing the band.