One of the most important factors in determining the number of implants is the type and design of the restoration they will support. This principle is known as prosthetically-driven implant dentistry. Counter-intuitively, the number of implants is not the first decision in planning the treatment, but rather the last!
First, we must determine the patient’s needs and what type of teeth, function, and aesthetics they desire. Do they want teeth that are removable or fixed? Do they prefer teeth that mimic natural teeth with no prosthetic gum tissue (if it’s possible to do) or a hybrid design that replaces the teeth and the gum tissue? What type of food do they want to eat? Food on the harder side like meats and nuts, or softer food like rice and pasta? And what is their anticipated occlusal load, which means how much force do they produce when chewing? The load is obviously higher in a large male with strong facial muscles than in a more petite individual with smaller facial structures. Additionally, we must determine the size of their arch (the sum of the width of all the teeth) and the type and quantity of bone. This is a process no different than an architect who determines the requirements for the foundation of a building only after having designed the building itself first.
By now you realize that one size does NOT fit all! Treatments must be designed based on personal needs and patient attributes and not on marketing trends. The treating surgeon who is placing the implants and the restorative dentist who is restoring them must collaborate on all diagnostic findings and together design a set of teeth that meets the functional, aesthetic, biologic, and emotional requirements of the patient. Only then can they determine the number of implants necessary to meet those objectives and whether bone grafting might be indicated to support the implants. The dental team must also consider the quality and quantity of bone and whether implants are planned in the upper or lower jaw, which are softer and denser, respectively.
This is called planning in reverse mode. First, consider what the patient wants, then determine the teeth design, then decide on the number of implants, and finally determine whether there is sufficient bone to support them or necessary to create.
Here, at our practice, we first perform a complete digital / computer assisted dental implant planning to determine the scope of the restoration and number and location of the implants. This is done through a cone beam CT scan merged with an optical scan (digital impression) of the patient’s teeth and then a virtual design and plan of the entire treatment. We can then provide our patients with an accurate plan.
Here are the general guidelines for number of implants in fixed implant-supported restorations:
- Hybrid design: 4, 5, or 6
- Fixed bridge design: 6 to 8*
- Hybrid design: 5 or 6
- Fixed bridge design: 6 to 8*
*Depends on size of arch, occlusal / bite pattern, and patient functional and aesthetic needs.
Dr. H. Ryan Kazemi is an Oral and Maxillofacial Surgeon in Bethesda, MD