Three implants in the edentulous maxilla to retain a removable prosthesis?

The number of patients, 23, and the period over which they were followed, namely 6 years is good enough for me to use this protocol. I would try to place the posterior fixtures as far distally as possible and the anterior fixture as close to the midline as is possible

The bone quantity and quality in the upper jaw is not great. You need to use at least four implants and preferably with a bar interconnected. Placing locator in such low bone quality at maxilla will put too much torque and pressure on individual implants and will increase the risk for failure. Locators works best in lower jaw where the bone is much more dense.

The results should not be discounted, but interpreted rather carefully. Previous studies have shown a higher failure rate with single anchors in the maxilla. The reasons cited include: greater off-vertical implant placement angle due to ridge pitch in the maxilla compared to the mandible; this results in greater off-axial loading of the implant and accelerated wear of the resilient insert and the abutment. The second cause of failure is of course the relatively soft bone and typically minimal cortical layer. Next, the maxillary prosthesis is subjected to greater lateral forces than a mandibular as the occlusion and tooth arrangement is typically buccal to the lower. There are limitations to the study: The study comments on absence of implant mobility or pain associated with them; this is really an inconsequential finding as implants are not mobile unless they are ready to fall out. Tenderness to percussion only seems to occur when the implant is in failure mode. Almost half the implants demonstrated bleeding on probing. is seldom a sequelae unless soft tissue is inflamed. The actual sample size is 12 patients with 2+ years. Bone loss is noted but there isn't a reference to calibration of measurement or baseline. In other words, the information is added to our continuing study of implant therapy but is too limited and somewhat unstructured to greatly influence one's treatment protocol. With reference to the idea of placing three implants in the maxilla, placing one in each posterior as far back as possible may not be a good choice, as it forms a long triangle, the legs of which are greatly inside the loading area of the canine-second bicuspid chewing zone. This will create a buccal lever arm which can rock the prosthesis. Also, the bone is typically less reliable in the molar area. I do not treat with solitary, maxillary anchors in edentulous patients, preferring to splint them with a rigid structure to prevent a bending moment and accumulation of strain at the implant site.

Addendum to my post: Legs of the long triangle being "inside," I meant lingually to the occlusal position, creating the buccal lever arm.