In 49 of the 51 jurisdictions tracked by the ADHA's Practice Act Overview (8.24.26 update), study cast impressions are listed as permitted hygienist scope — with required supervision ranging from a dentist physically present to full direct access.
Only two jurisdictions, New Hampshire and Wisconsin, show no listed level for this function at all.
Always confirm your exact state's current rule with its dental board.
The short answer
In most of the country, yes — the ADHA's Practice Act Overview (8.24.26 update) lists study cast impressions as permitted hygienist scope in 49 of the 51 jurisdictions it tracks.
Only two jurisdictions show no listed supervision level for this function at all.
Where it is listed, the required supervision ranges widely — from a dentist physically present in the room to full direct access, where the hygienist may provide it based on their own assessment.
That range, not a flat yes-or-no, is the real answer for most states.
Informational only — confirm with your state board
What a study cast impression is — and what it's used for
A study cast impression is a mold taken of a patient's teeth and surrounding oral tissues, using an impression material that's then poured in plaster or stone to create a physical model.
Dentists and hygienists use the resulting cast for diagnosis, treatment planning, and fabricating removable appliances like retainers, night guards, and whitening trays.
It's a documentation and planning function, not a treatment itself — the cast is a static record of a patient's mouth at a point in time, useful for comparing against later visits to track changes like tooth movement or wear.
Many practices are shifting to digital intraoral scanning for the same purpose, but the ADHA chart tracks the traditional physical impression, and that's the function this article covers.
Reading the supervision levels
The codes come directly from the chart's own legend:
- D — Direct Supervision: the dentist needs to be present.
- ID — Indirect Supervision: the dentist must authorize the procedure and be in the dental office while it's performed.
- G — General Supervision: the dentist authorizes the service beforehand but need not be present.
- A — Direct Access: the hygienist can provide the service based on their own determination, without specific authorization.
- "-" — not listed as a permitted function in the chart. That isn't the same as prohibited — it means the chart records no permitted supervision level for that state, so confirm directly with the board.
Where a state's cell lists more than one letter — like California's G/A or Hawaii's D/G — those are separate listed settings (commonly private versus public practice), never a range and never blended into one answer.
Quote the cell exactly as the chart lists it.
Study cast impressions supervision, by state
Quoting the chart as written, here is the supervision level listed for every jurisdiction.
General supervision (G) alone is the most common listing, covering 29 of the 51.
A direct-supervision requirement is the only listed level in 9 states — Alabama, Georgia, Indiana, Louisiana, North Carolina, Ohio, Pennsylvania, Rhode Island, and Tennessee — and Hawaii, Mississippi, and New Jersey list Direct alongside General as a separate setting, bringing the total requiring the dentist present in at least one setting to 12.
Only two jurisdictions — New Hampshire and Wisconsin — show no listed supervision level for this function at all.
| State | Study cast impressions supervision level (ADHA chart) |
|---|---|
| Alabama | D |
| Alaska | G |
| Arizona | G |
| Arkansas | G |
| California | G/A |
| Colorado | A |
| Connecticut | ID |
| Delaware | G |
| District of Columbia | G |
| Florida | G |
| Georgia | D |
| Hawaii | D/G |
| Idaho | G |
| Illinois | G |
| Indiana | D |
| Iowa | G |
| Kansas | G |
| Kentucky | G |
| Louisiana | D |
| Maine | A |
| Maryland | G |
| Massachusetts | G |
| Michigan | A |
| Minnesota | ID |
| Mississippi | G/D |
| Missouri | G |
| Montana | G |
| Nebraska | G |
| Nevada | G/A |
| New Hampshire | - |
| New Jersey | D/G |
| New Mexico | G |
| New York | G |
| North Carolina | D |
| North Dakota | G |
| Ohio | D |
| Oklahoma | G |
| Oregon | G/A |
| Pennsylvania | D |
| Rhode Island | D |
| South Carolina | G |
| South Dakota | G |
| Tennessee | D |
| Texas | G |
| Utah | G |
| Vermont | G |
| Virginia | G |
| Washington | G |
| West Virginia | G |
| Wisconsin | - |
| Wyoming | G |
Source: ADHA Dental Hygiene Practice Act Overview, 8.24.26 update.
Multi-letter cells are separate settings (commonly private/public practice), not a range — quoted here exactly as the chart lists them.
How this compares to the other functions on this chart
Study cast impressions sits near the permissive end of this 22-function chart, but it isn't the most permissive.
Six functions have no unlisted jurisdictions at all: scaling and root planing, x-rays, oral prophylaxis, fluoride, sealants, and topical anesthesia.
Study cast impressions is listed as permitted in 49 of the 51 jurisdictions — unlisted only in New Hampshire and Wisconsin — tying it with two other functions at 2 unlisted jurisdictions apiece, though not the same states: local anesthesia is unlisted in Alabama and Idaho, and Remove Perio Dressings is unlisted in Michigan and Pennsylvania.
It's considerably broader than soft tissue curettage (unlisted in 8), nitrous oxide (unlisted in 17), or Botox (unlisted in 48).
Don't assume permission for one function on this chart implies permission for another — the ADHA lists each one separately, and this article covers study cast impressions specifically.
Confirm your state's exact rule
A "-" on this chart means study cast impressions aren't listed as a permitted function in that state's row — it does not mean the state prohibits it outright, only that the chart doesn't record an authorized supervision level there.
Even where a level is listed, confirm exactly what it requires in practice, since practice acts and their interpretation change over time.
Start with your state dental board's practice act, and treat this chart and this article as a snapshot dated to 8.24.26 rather than a permanent rule.
For the rest of what a hygienist can and can't do, see our full breakdown of hygienist scope limits.
This article is general information, not legal or clinical advice. Scope-of-practice and supervision rules vary by state and change over time — confirm current requirements with your state dental board.