Are more implants better to support a mandibular overdenture?
It depends on where you put them. To improve denture stability with more implants, the implants need as much distance between one another as possible and they should be located in different spatial planes.
I once saw a case where a previous clinician had placed four miniature dental implants in the lower anterior segment of the arch. The implants were quite close together. The trouble was caused by the patient’s alveolar ridge that was not curved at all between the first premolars. This caused all four implants to exist in a straight line, creating a single fulcrum. Two implants would have accomplished the same result.
Ideally, it would be nice to spread four implants equally throughout as much of the full arch as possible, which is the “all-on-four” technique that has become commonplace today. The method works well as long as the implants are placed appropriately.
Facts About Dental Implant Placement
- Overdenture implants must be placed far enough apart so that the denture won’t rotate along any of the axes created by any two of the implants. This allows the denture to be truly stable and supported by the implants.
- Chewing forces must be directed along the long axis of each implant. If forces are directed in any other direction, one of the mechanical components will fail prematurely. (Abutments loosen over time, the denture breaks, retention nylons rapidly wear out, etc.)
- If an implant cannot be placed parallel with a common path of draw to the remaining implants, it is best to find an alternative location. Implants are only beneficial if they can be restored appropriately.
What about the technique of dental implant placement at severe distal angles to avoid the mental foramen in the premolar area?
While this technique may work, it doesn’t work in all cases. The technique requires the use of corrective angle abutments to allow the angled implants to be utilized. More hardware means more things can go wrong, for example, more components to wear out over time. Frequently, corrective angle abutments result in taller abutments than the patient has room to accommodate, which causes the restoration to be compromised in structural integrity.