Implant Retained Mandibular Overdenture Case: Best Length and Diameter Implants?

I would highly suggest a ct scan which will help you better determine your avaialble anatomy. Also, it will depend on how much room you have between the foramen if you can place two or four implants. Best to have a duplicate of the existing mandibular denture and have barium sulfate or gutta percha markers to wear while having the ct scan. The denture must be of good quality otherwise best to make a new one prior to duplicating in clear acrylic.

4 is always gonna be better than two. Misch has a great text book to guide you.

Dear Dr I, Thank you for posting this case. This is a very resorbed mandible and even from a brief glance at the panoral xray, I would be astonished if you had 20mm of bone in which to place your implants. Take Guy's advice and get a CT scan - BUT - only take one with the patient wearing a scanning guide. Otherwise the information is nearly useless as you won't know where the teeth are supposed to be. Let us know what the scan shows. Kind Regards, Bill Schaeffer

Dear Doctor I agree with Dr. Schaeffer, this seems to be a very resorbed mandible, and in my experience I don´t think you have 20 mm height. Are you considering the magnification of the Panoramic X ray? Get a good CT Scan and be ware on the width of the mandible so you have enough bone on the walls, in order to avoid a fracture. As I said it has a lot of resorption. Do a good diagnosis so you can plan 2 or 4. Good luck.

How old is the patient? I would guess fairly old who has worn dentures for a long time. Two implants for this person would be a great service. 4 implants would be too much due to a number of factors. His age, the thin mandible which could fracture in the premolar areas or even the anterior areas. There is very little force that he could apply to the denture because of the upper denture. You could easily reline his existing using locator attachments.

Dear all , mandibular bone is resorbed. we are dealing with it every day. From the x ray and evaluation of DR.I there is enough bone to put 4 implants, regular size or you can consider MINI implants, putting in consideration you are dealing with compact hard bone. CT scan will confirm your plan. the area between the mental foramens is the working area. some more X rays with radioopaque materials will clear the anatomical landmarks you work with .In this type of bone you can also immediate load the denture in place to take advantage of the bone density. Good Luck DR.Ali DDS,MS New York

Hi Dr. I A C.T. will give you the bone volume and density information you want. Positions #22, 27 (canine) provide excellent width and stability for two(2) implants (probably 10mm.length). Locator attachments work very nicely for this overdenture situation. Regards, Theodore M Grossman DMD Oral & Maxillofacial Surgery

Remember that the trajectory of the lower resorbed ridge is more lingual at teh crest adn angles toward the facial. This x -ray is two dimentional this can be fooling on length that you truely have. The other concern is the type of bone. The boen will be very difficult to drill and be careful not to over heat the bone. I like bars adn you could do two to four implants.Abar will help if you have angulation problems. A CT will and a surgical guide may be a good idea to cover the bases.

Get a cone beam with gutta percha markers in his existing denture to help localize the mental foramina and any lingual undercuts. Place the implants in the 23 and 26 sites. Much farther back and the denture will want to rock around the locators when the patient incises. All you need are two 4.0 by 10mm implants, whatever system you like. Make sure they have locators available for them. Four implants and a bar is another reasonable choice but the cost goes up dramatically so, if retention is what you're after, two is fine.

Thank you, Dr. Grossman, for answering a question straightforward. Too many comments repeat useless information. Yes, a CT scan might be useful, but we all know that a regular platform 10mm implants will perform nicely in this situation, and there is almost certainly 15mm bone. You find you have more bone, so you will place longer implants?

I may have missed this, but did you mention buccal-lingual width? I'm not sure how a diameter could be recomended without this information.

A cone beam scan is essential (and less radiation than a CT). Only 2 implants required, and these should be as far laterally as possible to give maximum denture stability. However premolar sites in this case are too risky (mental foraminae) so canine sites are the ones. The implants will be angled posteriorly (apex to crest) so think about GPS retainers (Locator clones that are cross screwed and 30 degree angled). Decide implant length and width when you examine the scan. Drill slowly with sharp drills and chilled saline irrigation so as to avoid burning the dense bone (remember dense bone is not very cellular or well supplied with blood vessels). Remember that the blood supply in the resorbed mandible is mostly from the periosteum, so try not to raise flaps or you compromise the already poor blood supply to the bone. Use the existing denture as your radiographic and your surgical guide. You can drill holes in the anticipated sites and fill with gutta percha for the cone beam scan, and then drill out the gp and use the holes to guide the pilot drill through the intact mucosa. The holes may follow the radiographic guide holes or may need to be adjusted according to what you find on the scan. Good luck

the pan shows severely atrophied ridge in height. It looks like it may be at the same level as the floor of mouth with very little vestibule left. In such cases, I like 4 implants with a bar instead of 2 implants with locators. It's more comfortable for patient as you can fabricate the prosthesis so it doesnt impinge on the muscles by the floor of mouth.

A CT scan, two regular or 4 minis, well fitting denture!

This is a D mandible and need to look at doing a subperiosteal implant. If placing root froms in this mandible could cause a fracture in the jaw. if done correctly is one of the best implants. Good luck

Joe says; "Yes, a CT scan might be useful, but we all know that a regular platform 10mm implants will perform nicely in this situation, and there is almost certainly 15mm bone. You find you have more bone, so you will place longer implants?" Comments like this one above make me shudder. I will paraphrase it for effect here; "hey, I've looked at the 2 dimensional x-ray and I can tell you that the 3 dimensional bone volume is almost certainly 15mm. Hell, if it's not then you'll only be going through the lingual cortex in the region of the lower canines and that's probably going to be OK right?" Dr I, really really bad things can happen if you get this wrong, so get a CT or CBCT scan, performed with some kind of scanning guide (so you know where the teeth are supposed to be) and let us know if there's 15mm of bone in the positions where you need it. Kind Regards, Bill Schaeffer

I would not see any problem to place two 10mm implants in regio 33 and 43.Then locators or (better)telescopes. Maybe three implants,but with four the risk of fracture seems too high.The bone will be hard as stone,so have sharp drills and a thread-cutter ready.

I think go with 3.5 mm platform implants, 10mm with locators. Patient will get good retention

What does the patient want? If this patient would be happy with an implant stabilized denture as opposed to an implant retained denture then mini implants are the way to go. With bone this hard immmediate load on the mini implants would be little problem. The existing denture (provided it is well made) could be retrofit so that the patient would be functioning with the new implants the same day. Much lower risk of jaw fracture and perforation of the lingual plate. 2mm x 10mm or longer would work well. 4 mini implants would be needed. If your patient needs the implant retained lower denture you absolutly need the scan and surgical guide. Be careful as it is very easy to overheat bone like this and you can not risk any more bone loss. There may not be a second chance at placing endoseous implants here.

Dr. Kusek, You are 1000% correct. Another good treatment is a ramus frame. One can squeak by with a two on the floor case, but the sub or ramus frame are the best. Even a Todd-Pinto sub would be great. Unfortunately, these procedures are beyond the belief, understanding and capability of most implant dentist (rootformologist).

I vote mini implants, if anything, but you really need an ICAT or similar available during surgery to verify correct angle and depth of placement. Believe me, it helps a lot and is much easier (and more accurate) than a scan guide.

Dear Dr. I My opinion is that you are missing some important information: 1 - You need to know the bone width and the mandibular shape. So, you need a CT scan. Than, you will be able to choose which implants are suitable to place (diameter and lenght) 2 - You should put the focous on the patient. I mean, what doyour patient wants? A fixed prothesis? So you need to place 4 implants (do you Know the all-on-4 technique?) Or your patient would be happy if you simply gain retention to use a removeble denture? So, you only need 2 implant in the canine area. 3 - Don't complicate. Keep it simple. Let us know the CT results and your decision

Dear collegue Clifford! I have been working many years with mini implants and I stopped it.Many broke,especially in very hard bone,and,second, the heads wear off and you loose retention after 3 to 4 years.In my eyes ,the decision in this case is not so hard to find.A fixed bridge is only possible after extensive and expensive augmentation.So why not place 2 or 3 imlants between the foraminae and put a telescopic removable denture on top of it?

Dr Friess - I have broken 4 mini implants in hard bone out of hundreds placed. All were Imtec, not MDL. I have had two break in function, both on uppers in the same case, both were Imtec. No breaks at all since I learned to apply force judicially and switched to MDL. Never seen a head worn down so it wouldn't work, but I've only been doing this for five years. Like all of us, we can't point to 30 years experience because minis have only been used extensively for a few years. I have no problem if you decide never to use minis, but I think it is very appropriate (and the only choice) for many cases.

I agree with Dr.Clifford on some points he's made. I've placing minis an traditional for some years now and I haven't seen any mini break off yet. I use MDL and small diameter implant from oco biomedical, zimmer. Haven't used imtec. But I don't see what some others are claiming of implant heads breaking off or them losing retention. I have seen it with implants that are bigger than 3.0mm but that could simply mean Ive place dmore of them. But minis do work. If not, you are not doing it right or picking wrong cases. I don't use minis for max denture stablization due to unpredictable result. I think it's best to use implant system with locators for max. overdenture. Just my 2 cents.

Dear collegues! I don´t really know,but I think ,that the telescopic concept is not so widespread in the U.S. as it is here in Germany.For me,it is a very good concept,which gives me much more ellbow room and it works even with minis.There are abutments for minis on the market with which you don´t even need primary teleskopes. Of course the parallization is quite easy acquirable espescially with inner galvanos.Plus, it takes even less space than the housing.Of course it´s more expensive.

Dr. Hughes is correct. A Ramus Frame would be ideal in this situation. The patient would walk out the door after an hour and a half procedure with a stable provisional denture secured on the ramus frame. This was truly the first Teeth in a Day procedure. http://sojinstitute.co.uk/PDFs/Implantology/7_Blades_SOJ/rb7Ramus%20Frames.pdf

The treatment of choice is 4 O-ball head mini dental implants with 4 corresponding O-ring and housings cold cured to the lower full denture. Tarnow and some others has described this method as very acceptable and predictable. It is also less costly, less traumatic and the patient can enjoy it almost immediately. This issue has been thoroughly and entertainingly debated and analysed in this Osseonews website under "Resorbed Mandible Case: Best treatment plan?". Cheers.

i agreee that dentasacan with radiopaque material to know where implant site (radiographic stent ) , well fitting denture and two implant is satisfactory to avoid complications ,especially the oppposing is denture not natural teeth, the 14 mm length with the diametre that is determened by dentascan. best regards