Clinical Guide to Denture Occlusal Rims: Function, VDO, and Step-by-Step Application

Denture occlusal rims—also known as bite rims—serve purposes beyond simply recording a patient’s bite. They play a key role in helping your technician select appropriate tooth size and shape, establish the correct incisal edge position, and determine esthetic gingival contours for the final denture.

Bite rims are fabricated with wax placed directly over the patient’s residual ridge, offering the most stable foundation for setting denture teeth to ensure optimal function and longevity. These rims also record the patient’s occlusal vertical dimension (VDO)—the vertical distance between the upper and lower jaws when teeth are in proper occlusion. A correct VDO results in a natural appearance of the nose, lips, and chin. An excessive VDO makes it appear as though the patient’s mouth is overfilled, often preventing lip closure around the rims. A deficient VDO gives the appearance of a collapsed mouth, with the chin too close to the nose and the corners of the mouth turned downward.

During baseplate fabrication, your technician may need to block out any undercuts on the master model to prevent breakage. This can result in a slightly loose-fitting baseplate during try-in. In such cases, a small amount of denture adhesive may be used to improve stability. Once the denture is processed, the fit will be precise.

STEP 1

Before trying in the bite rims, measure the patient’s VDO. If the patient has existing dentures, place a mark on the nose and chin, and record the distance between them. For edentulous patients or those with worn dentures, estimate the VDO and adjust the wax rims as needed until the desired vertical measurement is achieved.

STEP 2

Assess lip support by observing the patient’s profile. The anterior edge of the upper wax rim should align with the anticipated position of the upper incisal edges. Ask the patient to speak with the rims in place to confirm that the edge allows for comfortable speech and esthetic tooth display—especially important when managing Class II or Class III relationships. Modify the wax as necessary to achieve proper incisal edge position.

STEP 3

Verify the occlusal plane by ensuring the upper wax rim is level from side to side. When the patient smiles, the incisal edge should be evenly visible along the lip line. If adjustments are needed, mark the corrected plane by scoring or drawing a line on the wax. Indicate the midline by marking the exact center of the patient’s face. Also mark the approximate canine positions, which typically align with the corners of the lips at rest. Record the lip line when smiling—this will guide tooth selection and placement. After finalizing measurements, apply impression material to the lower wax rim and guide the patient into centric relation.