Implant-Retained Overdentures: How Many Implants in Midline and Canine Sites?

Dear Anon, the midline implant for an overdenture doesn't seem like a good idea. The midline is the weakest part of the lower denture and is prone to fracture. If you can only place one implant, place it away from the midline. And as for design or number of implant, the more the better, that's all. It all depends on how much the patient can afford.

Anon, Kilik has a good point with just one implant. If I can elaborate on that. The one or two implant designs can work, however, you will only create some lateral stability (referring to the mandible). With only two implants, every time the patient starts to chew sticky food we will get posterior lift. If using free standing implant abutments like the ERA or any other attachment, I would recommend a minimum of three attachments for the mandible (the bicuspid areas and slightly off the midline). The maxilla represents other issues, particularly where most patients like to go palateless when they pay for implants. The minimum I would recommend here would be 4. This will ensure a stable prosthesis. With regards to going palateless in the maxilla, I would not do it without a metal substructure and at least a strap across the post-palatal seal area. Hope this helps.

Do not use just one root form. You will have too much lateral and a-p movement. Use two at the least. With two you will have an a-p moment and possable gingival irritation. Think of four to six implants and stay off the midline.

2 implants in canine site or lateral sites is the min treatment,if it is possible for 4 implants,it will have better stability and comforte.putting implant in midline is a personal experiment not a scentific evidence.

One question for you...would you rather have a three legged chair or a four-legged chair....It may have worked on some of his patients, however so has immediate placement and function but overall experience the results are always satisfactory in the long-term...I urge you to keep from cutting corners...the body heals and functions in a certain way and we all need to understand this and quit trying to change what we have no control over

One implant in the midline will hardly offer ANY stability, just retention. On the other hand, two in canine area may be just enough (mandibula) and anyway, if you can place one in the middle, you should always be able to place two on both sides, so I don't see any rationale for one.

RB and Ritman have a view, i just want to added some tips, its depends also with the denture that u use for the over denture. is it stabled ? or loose ? maybe you should consider about doing rebasing. the lateral movement or a p movement can make the implant into trouble such broken or failure ( in the case of mini implant ) also the plastic for bar attachment and rubber for the housing you should keep maintain them. this is the most important for the overdenture. plastic cant last 10 years in your mouth neither do rubber or else

you gotta consider arch form and max or mand. a narrow v-shaped small arch w/ 2 implants is not gonna rock w/ 2 implants at canines. a large, ovoid, long arch is [a-p rocking].this is on the mand. arch. on max. it almost always does w/ only 2. the max will rock w/ 4 if you place them at sites 6,8,9,11 and the arch is a long v-shape but wont if its a wide ovoid shape.definitely have a metal subframe like the other guy said.

we forget, we´re talking about a mucouse suported denture. Implants are not suppose to hold all the charge of the prothesis. In an overdenture the better way to improve retention and stability is placing two implants in the place of canines. You get better suport with an aditament like Era or Locator than with oring. if you work properly the prothesis and oclusion you can almost avoid posterior lift.

I like to minimally place 4 implants. 2 in the canines and the other 2 in the lateral areas. The denture is usually very stable. Stay away from the 1 implant in the midline.

With two implants the case is implant retained.As soon as you introduce the 3rd or 4th you lose this. Now you have a tripod or table and the case is now implant supported.That doesn't mean it won't work it just changes the physics of the case and you should have this factored into the big picture ie: bite,opposing arch etc. to assure a favorable outcome.

RB with 3 legged chair is using wrong analogy ...this is an over denture not a fixed bridge that is implant SUPPORTED In over dentures more implants more RETENTION ..simple Stability is different ..one or 2 implants will have denture rocking around the implant ..2 implants will create a straight line axis that will always tilt with function..it can work but 3 is ALWAYS better creates a tripod and thus no tilt and good stability ..good retention. NOTHING wrong with midline placement at all..for overdentures

Dr Mosery Just because you do 4 implants does NOT make this implant supported The physics change if you construct the prosthesis accordingly You can CHOOSE to make 6 implants into a denture retained case...look at all the Mini Implant cases! You could make 2 implants into an implant supported case ..not wise at all but you can ..and it will fail! Readers MUST appreciate difference between Implant supported and Implant retained Check out the text by MISCH ... probably the most accomplished Implantologist in the world today

Using 2-4 implants in the anterior mandible to support and retain an overdenture is already an established treatment approach with now up to 10-15 years of documented outcome. Using just one implant in the midline has also been successful in improving mandibular denture retention and stability particulary for older patients with up to 5 years of follow-up (see Cordiloi et al 1997)and another 4 studies of lesser follow up (one year). This could be now considered as the minimal and least invasive option when indicated. The problem with placing an implant in the midline of the mandible is not related to possible fracture of the overdenture as this event has been rarely reported with this approach but rather the anatomical restrictions of this region particularly with severe ridge resorption. Early days of implantology avoided placing implants exactly in the midline of the mandible because of the dense bone present which might generate excessive heat during placement leading to failure which now has proved to be less critical than previously thought. The last point I would like to add is that the number of implants needed in reality is realted to patient's demand and perception of what could be adequate for him which varies. If we are to put 4 implants then I think we should consider a fixed restoration (when case is suitable) rather than just an overdenture. Look at the work of Malo in portugal with the all in 4 approach.