Inside Dental Technology
A Perfect Fit
Deeley Centerline teeth provide a secure, comfortable fit for a patient frustrated with denture adhesive.
By Alan Deeley, AD, ACS, CDT
In an effort to remedy ill-fitting dentures, some patients look for their solution at the drug store—over-the-counter denture paste. Many of these products have some serious potential side effects, which in some cases can lead to major health issues. Lisa Sanders, MD, published an article in the New York Times Magazine (Sept. 6, 2009) that described a patient who overused denture adhesive, resulting in zinc toxicity and a number of debilitating side effects.
After reading this piece, a patient came to the dental office requesting new dentures with a better fit so that he would not have to continue using denture paste. An evaluation of the patient’s oral tissue condition revealed several irritated areas in the mouth. The patient admitted to routine use of denture adhesive. Casts of the dentures showed extreme wear, especially on the right upper and lower posteriors (Figure 1).
The patient wanted a lighter tooth shade in his new dentures but a tooth size similar to his current set. These two factors are crucial in making a good tooth selection. Many times, a digital photo of the patient is also very helpful for the laboratory.
Next, the dentist used the Knebelman Craniometer (Craniometrics Inc., www.craniometer.com) to determine if there was any loss of vertical dimension, then read and set the patient’s facial dimensions to establish a correct vertical (Figure 2). Alginate impressions were taken of the upper and lower arches and sent to the laboratory, where casts were poured for bases to construct trays for the final impressions and a bite recorder. A bite recorder is a device designed to take an intraoral Gothic arch tracing.
The trays that the bite recorder were mounted on were returned to the dental office and placed in the patient’s mouth. The bite recorder’s ball-bearing stylus was used to determine a more accurate recording of jaw movements to find the apex of the maxilla and mandible. When the apex of this Gothic arch was reached, a stop was placed at the center point and the patient closed on the stylus.
The craniometer was used to verify vertical dimension. The bases were then locked together with a polyurethane bite registration paste for an outline of the inner surface of the lips, and the midline was marked with a fine-point dental instrument. This enabled an accurate set-up of the anterior teeth.
The upper porcelain anteriors used were VF Harmonique™ mold 20U - shade A3, and the lower acrylic anteriors were Dual Form V® mold L12 – shade A3. The posteriors were Deeley Centerline (Linear Blades) mold M – shade A3, which are made in blocks of four—right and left, upper and lower. The lower teeth are designed with a stainless steel, straight-line buccal cusp. These teeth enabled the laboratory to decrease production time and increase accuracy, benefiting the patient and the dentist.
At the laboratory, the ball-bearing bite recorder was used to mount the casts on the articulator (Figure 3). The anterior teeth were set and arranged according to the polyurethane paste lip outline (Figure 4). There was a slight clearance between the incisal edges of the upper and lower anterior teeth. A stainless steel template was used to form a plane (Figure 5) from the lower anterior teeth to two-thirds of the height on the retro molar pads of the lower casts.
The lower posterior blocks of teeth were set to the plane of the stainless steel template (Figure 6 ). The upper blocks of teeth were set to the lowers. The Centerline blade contacts the center of the upper posterior block of teeth (Figure 7). There was no contact of the lingual surfaces. A 0.5-mm space on the lingual is needed to form a total linear contact.
The dentures were returned to the laboratory and processed in high-impact denture base material overnight. The next day, they were re-mounted on the articulator to refine the occlusal contact. Corrections were made only to the upper surface on the block posterior teeth. This initial refinement was done on the articulator to eliminate any interference with the liner occlusal contact.
On the day of delivery, the dentist checked for any oral tissue discrepancies and overextensions as the dentures were placed in the patient’s mouth. Carbon paper was used to observe the initial linear occlusal contact.
The blade on the lower posterior block of teeth must touch the upper occlusal surface in a straight line. Linear occlusion places the upper denture firmly against the palate and surrounding tissue and the lower denture firmly down against lower supporting tissue.
The linear blade allows the patient to penetrate food with less effort than conventional cusp posterior teeth. These dentures stay seated during all forms of mastication, thus eliminating the need for denture paste and providing a healthier and more satisfying solution to the patient.
The preceding material was provided by the manufacturer. The statements and opinions contained therein are solely those of the manufacturer and not of the editors, publisher, or the Editorial Board of Inside Dental Technology.
About the Author
Alan Deeley, AD, ACS, CDT, has given lectures and clinics on linear occlusion throughout North America and spent most of his career in the laboratory business with his father at Deeley Dental Laboratory in Youngstown, Ohio.