Is the first step of a dental hygienist's cleaning the probing of teeth pockets?

Not necessarily: If the patient has a large build up of calculus, then the calculus needs to be removed first so that the periodontal probe can go to the base of the pocket. Probing and periodontal charting needs to be done with a mouth free of calculus to be accurate, otherwise pockets may be charted smaller than they actually are.

Yes: Pocket probing is an important part of your periodontal examination. This will give your dentist much information on the health of your tissues. This will be done before any treatment like scaling, is begun. This will provide a baseline for evaluating and monitoring your response to scaling. It will be repeated. It is not done at every appointment.

Periodontal exam: A complete dental exam should include evaluation of one's periodontal health. Periodontal probing is normally part of that comprehensive evaluation. It's often unnecessary to probe children's pockets when it is visually apparent that they have excellent gingival health. As they get older, it becomes more of the necessary routine. If recently probed, a hyg need not probe first.

Depends: Probing is a good way to quickly assess the overall condition of the gingival tissues surrounding teeth as it not only measures bone pockets, but bleeding points aswell.

Frequently: The dental hygienist performs many procedures during a routine visit. They will include general overview of your teeth, medical history update, x-rays if indicated, oral cancer screening, periodontal exam (which includes checking for existing pockets and/or updating current records), removing plaque and calculus from your teeth, flossing, looking for cavities, and polishing your teeth.