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In a Technological World, Basic Morphology Sets the Table
Peter Pizzi, MDT, CDT
Over the years, there have been many great articles written on occlusal concepts, several of which have come from IDT. Every CAD system on the market has many occlusal libraries to choose from, and yet many restorations need adjustments. One of the challenges that we face in occlusion—regardless of whether it's built by hand, using CAD/CAM, or even a combination of both—is the adjustment time that our clinical partners spend inserting our restorations. Managing the occlusal table's width can prevent gross adjustments and ease the management of occlusal equilibration on insertion.
It's important to note that the main purpose of posterior teeth is to crush and grind the bolas of food. Every angle, incline, convexity, or concavity plays an important role in the mastication process. For this reason, understanding tooth-to-tooth relationships is key to our success (Figure 1).
Technicians spend a great deal of time creating ideal esthetic and functional restorations, but our dentist partners often spend too much time adjusting our work, creating a difficult environment for the entire dental triad—dentist, technician, and patient. The main reason for the disconnect between technician and dentist is the lack of understanding of the dental occlusal table. As we examine teeth from the occlusal view, the eye sees two main aspects: first, the optical width of the tooth, which is determined by the buccal and lingual volume of the tooth (Figure 2), and second, the anatomical structures or occlusal morphology, where mastication takes place. If asked which tooth has the widest area or table for mastication, many technicians would say the maxillary first molar (Figure 3). The problem here is that regardless of hand fabrication or CAD fabrication, this response is not correct. The optical volume that we are able to view from the occlusal plane differs from tooth to tooth (Figure 4), and the occlusal table's width is virtually the same from tooth to tooth (Figure 5). It is this occlusal table that allows mastication to occur, while the optical view and angle help to guide the masticated food toward its entry point of the body and away from areas that can cause issues.
The angulation of the mandibular buccal cusps and the maxillary buccal occlusal incline planes are what help to keep the food on the occlusal table (Figure 6). Managing this area will aid in our understanding of occlusion and anatomy. By placing the cusps in the correct position, we gain more space and allow our dentist partners to have much less adjustment time, thus creating a more agreeable atmosphere for the dental triad and ultimately benefiting the patient.
Bench Essentials is a quarterly series in which IDT Editor-in-Chief, Peter Pizzi, MDT, CDT, presents educational lessons about the fundamentals of dental laboratory technology based on his decades of working at the bench and lecturing around the world.