# How large is an ideal operatory?

How large is the ideal operatory? Unfortunately, the answer is not that straightforward.

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How large is the ideal operatory? Unfortunately, the answer is not that straightforward. Esoterically speaking, the ideal general practice operatory is 10' 5¼” x 11' 9¼” to face of framing.

What precisely is an operatory? According to Merriam–Webster's medical dictionary, an operatory is a working space (as of a dentist or surgeon). In the modern dental facility, a working space for the dentist definition of an operatory leaves much room for interpretation.

In our design work, we define an operatory as a highly specialized space configured to deliver dental treatment to patients while supporting all associated tasks performed by the dentist and auxiliaries.

The rationale for this 10' 5¼” x 11' 9¼” dimension is built around the seated treatment position of the dentist (operator), auxiliary, and patient in the reclined position. A reclined dental patient chair has an approximate footprint of 2' in width and 6' in length.

The next component in this sizing rationale is to provide adequate clearances around the fixed footprint of a 2' x 6' reclined dental patient chair for patient access and dental team positioning.

For many years, we designed a 27” clearance perimeter around the reclined chair footprint and any fixed obstruction with the exception of the chair's foot end. At the foot end of the operatory, the clearance between the chair and wall was reduced to 18”. The 27” clearance on three sides of the chair is based on the anthropometric reaching distance of an average–sized female, which is 27”. The 27” clearance often created ADA (Americans with Disabilities Act) issues for wheelchair access to the patient chair. A manual wheelchair has a width range of 24.5” to 26.5”.

How can you force a wheelchair into a space that has less than 1” clearance on either side? Not easily ... and, of course, that scenario is not code–compliant. The solution was to temporarily rotate the patient chair on the base and create a code–compliant clearance pathway of 32” on one side of the operatory.

We now recommend increasing the clearance perimeter around the reclined dental chair to 32”, with the exception of the 18” clearance at the foot end. In addition to wheelchair issues, 32” clearance better supports today's expanded footprint of delivery units, stools, mounted monitors, mobile scanning units for impressions and restorations, mobile lasers, mobile bleaching units, storage requirements, and fortunately, patients, dentists, and staff.

The 2' x 6' chair and 32” clearance perimeter establishes a 7'–4” x 10'–2” footprint. Outside this footprint, we can place equipment and cabinetry to complete the operatory dimension. In general practice operatories, we find few functional drivers to design supporting cabinetry and countertops to a depth greater than 18”. Cabinet depths less than 18” create issues with sink sizing, trash receptacles, and other standard–sized cabinet accessories.

Allowing for an 18” cabinet depth at the head end and both sides of the 7' 4” wide x 10' 2” length footprint yields an operatory dimension of 10' 4” x 11' 8” to the inside finished face of the surrounding operatory walls. A framing carpenter typically wants to reference dimensions drawn to the face of the framing, not the finished wall surface.

In dental facilities, we recommend 5/8” gypsum board as opposed to ½”. The depth of finished materials placed on the gypsum board is considered negligible. Therefore, the face–of–framing dimension for an ideal operatory, taking into account 5/8” gypsum board on each wall surface, is 10' 5¼” x 11' 9¼”.

In design and construction reality, it is not time efficient to create plans in which the majority of dimensions deal in fractions of an inch. In “real world” dimensions, our plans typically display operatory dimensions of 10' 5” x 11' 9” to face–of–framing, give or take an inch or two depending on existing conditions.

This ideal operatory also assumes dual 32” entries without doors at the head end of the space, a large north–facing window at the foot end of the space, ½ ton of HVAC output, a 9' A.F.F. beam for patient light, a 10' A.F.F. acoustical tile ceiling with indirect lighting, a 7' A.F.F. header at each opening for sound control, an inspiring mix of finish materials creating a calming and healing environment ambience, state–of–the–art equipment and technology, and nine or 10 other things.

Jeff Carter, DDS, and Pat Carter, IIDA, are owners of PDG– Practice Design Group. Located in Buda, Texas, PDG offers a full range of design and consulting services to dentists nationwide. For information, call (800) 511–7110 or visit www.practicedesigngroup.com.

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