The level of PPE that is required will depend on the procedures that are performed. The ADA notes that "under OSHA, PPE is considered “appropriate” only if it does not permit blood or other potentially infectious materials to pass through to or reach the employee's work clothes, street clothes, undergarments, skin, eyes, mouth, or other mucous membranes under normal conditions of use and for the duration of time which the protective equipment will be used."
Mask shortages are indeed a problem in some areas. It may be advisable to use different levels of masks for various purposes in order to preserve the most resistant masks for where they are necessary. The CDC guidelines for mask use have not changed, and the requirement is that masks are changed between patients (and during treatment if the mask becomes wet.)
The ADA recommends Level 1 masks for patient evaluations, orthodontic visits, or operatory cleaning. These are procedures where low levels of fluids, aerosols, or spray are produced. Level 1 masks have the lowest levels of fluid resistance and filtration efficiency.
Level 2 masks provide a "moderate" barrier and are more appropriate for moderate levels of fluid, spray, or aerosols. These may be used for sealant placement, endodontics, or simple restorative or composite procedures.
Level 3 masks are best for procedures such as crown or bridge preparations, complex oral surgery, implant placement, or use of ultrasonic scalers. These procedures generate moderate or heavy amounts of blood, fluid spray, or aerosol exposure and so are best suited to the mask with the maximum level of fluid resistance.
N-95 respirators are different than surgical masks. They must be fit-tested for proper use. If your practice decides to use N-95 masks, OSHA has published requirements for medical evaluation and fit-testing.