3 implants for mandibular overdenture: is this more stable?
I have a patient who is treatment planned for a mandibular overdenture retained by 2-implants. I am wondering if this overdenture would be more stable if I used 3-implants: 1-implant in the midline between[between #25 and 24 sites; mandibular central incisors sites; 41, 31]and 1-implant in #26,23 sites [the right and left lateral incisor sites; 42, 32]. In the past I have only used 2-implants to retain mandibular overdentures but I am wondering if 3-implants would triangulate the forces and be more stable and more retentive?
10 Comments on 3 implants for mandibular overdenture: is this more stable?
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CRS
1/26/2013
I like to place four implants between the mental foramen, belt and suspenders if one fails. However how are you restoring, bar or locators? Often my restoring colleagues play with the amount of retention and sometimes the extra implants have a neutral female attachment in the extra implants. With bars I like three implants to avoid the "football goalpost" with two implants and rotation around the bar as a fulcrum. What is the A-P spread of the implants, posterior height and balance of the mandible? A posted panorex would be very helpful.
Diorgenes Machado
1/29/2013
If you are using 3 implants place them it in the midline and in the 1st premolar sites. It´s a a better spreaded polygonal configuration.Three implants in this configuration can be used with bar between implants, bar with a litlle cantilever to posterior or locators. If you want to upgrade to fixed hybrid prothesis you can add 2 implants in the lateral incisors sites and/or the 1st molar sites.
Michael Stanley
1/29/2013
Misch recommends maximizing the AP spread. With 3 implants, that means two between the foramena and the third as far posterior as you can manage. This permits some of the natural mandible flexion despite the connection bar. His system doesn't rigidly attach left-to-right posterior of the foramen because it either prevents the flex (causing pain, dysfunction, etc.) or causes the implants to fail.
Draw an arch and try to position three points as far anterior & posterior as possible.
Carlos Boudet DDS
1/29/2013
Three implants are better than two for several reasons.
One of the best reasons goes back to engineering or design principles. The anterior implant serves as an indirect retainer, just like the function of a linguoplate or a rest in a canine for a distal extension partial denture.
The third mplant also provides more retention.
I would not place in the exact midline, but in the position of 24 or 25 (the central incisors), in case the patient decides to upgrade to fixed later on.
Misch talks about the five intraforaminal implant positions ABCDE for fixed prostheses.
But the answer to your question is yes, three is more stable and more retentive.
MIHAI
5/29/2016
"Misch talks about the five intraforaminal implant positions ABCDE " FOR OVERDENTURES.
dbe
1/29/2013
absolutely better other than cost. eliminates rocking . 2 implants creates straight line. 3 a tripod with no rotation.my dad loves his 3
Dr. Amit K. Gaba
1/29/2013
Definately 3 will be better than 2...........other than above mentioned brilliant explanations.......Biophysics is also there...... load distribution will be more even and tripod effect gives stability compared to bipolar ball abutments.
Trevor Knowles
1/30/2013
I would like to respectfully note that the suggested positions (lateral incisors and mid-line) are quite close together. These are essentially in a straight line, so the center implant is not eliminating the fulcrum as suggested. If your treatment plan was to place two implants in the first premolar position rather than the lateral incisor position, then I would strongly support the addition of the third implant for the reasons previously posted.
uli friess
1/30/2013
dbe is right!I`ve been doing this for 35 years and it works much better , than just 2 impl.
Sammy Sandhaus from Lausanne used to call it a "bouquet de trois"
dr. bob
1/30/2013
Place as many implants as you can. The loss of one implant if only two are placed may result in a case failure that can be costly to repair. The real question here needs to be answered in the treatment planning. Will this overdenture be supported in part or on whole by the implants, or when the patient bites on it will the forces be transferred off of the implants and be borne by the tissues? Then the implants only resist displacement of the denture and have little load on them. An over denture can over load implants and cause then to fail. If you are going to use only two implants please try to design the case as to load these implants in a way that allows the denture to settle onto the foft tissue and lessen the load on the implants.
