NMDA Journal Summer 2020

trained or licensed to do. The treatment process should be a collaboration of card- carrying dental partners to create superb, beautiful, hygienic, long-lasting, and occlu- sal functioning restorations. The process is anything but easy and demands open and coordinated team work. The classic or Branemark strategy in restor- ing completely edentulous patients involves using an adequate number of dental implants, usually six plus or minus two more in front or behind the canines or sec- ond molars. This approach may involve sinus grafting in the maxilla to support all the implants. The fixed prosthesis is placed after osseointegration. The AO4 strategy spaces four dental implants in the arch (in the maxilla such that there are two anterior implants and two posterior implants avoiding the maxil- lary sinus). They are loaded immediately to a prefabricated complete denture sans pal- ate. This provisional or conversion prosthe- sis should stabilize all the dental implants (the implants are solely mechanically retained) as well as giving the wearer an immediate fixed prosthesis which remains in place for three to four months when the final restoration is fabricated. A hybrid of the two above two strategies is to connect the implants with a bar and passively retain the dental prosthesis. Now comes the potentially serious prob- lems with the All on Four: 1. If the prosthesis has any flange over extension that ridge laps the maxillary or mandibular arches, there is no way that it can be hygienic leading to retained food debris that cannot be removed by the wearer. The soft tissue can become seriously inflamed and infected (foul smelling) leading to com- plete implant failure. (See photos on right.) 2. The cantilever and occlusal forces deter- mined by vertical and horizontal space requirements of the AO4 as well as the traditional implant restoration have to be engineered so that there is no micro movement while the implants osseointe- grate so that they do not ‘rock out’ or instability creating prosthetic material breakage. Photo courtesy of Cynthia Colson. Photo courtesy of Cynthia Colson. continues on page 12  11 Musings: The All on Four nmdental.org