Is an overdenture made to a splinted bar really a superior restoration?

Yes and no: Free standing implants in the maxilla have a much higher failure rate than those that are splinted. Some of the prosthetics like Conus, seem to overcome this yet the research is scant. In the mandible, I'd do free standing implants all day long. I would recommend that you have a metal mesh in the prosthetic and you may need alveloplasty to accommodate the required thickness of materials for minimal maintenance.

I agree with the first comment. Usually the maxillary implants flare facially so locators or balls don't draw and have increased wear. I always splint max. Implants with a bar. The other determinant is the AP spread. I will only use free standing locators in the mandible if the posterior implants can be placed in the first molar sites. If the only bone is anterior then use two and studs, 4 and bar overdenture or fixed hybrid. In my practice the maxilla is always a minimum of four then bar or hybrid (preferably more than 4). Again splint for better success and to spread the attachments further apart which will increase the AP spread for a more stable and functional prosthesis.

I should first point out that my clinical preference is to insert an implant retained denture or bar retained over denture in preference to a fixed hybrid bridge. The reason is because of implant maintenance and I mention that I have been able to “rescue” many failing implants by removing fixed implant bridges and replacing with easily maintained removable prostheses. Interestingly the vast majority of patients seem to prefer a removable appliance since they can more easily clean their implants and prosthesis (especially if they smell their hybrid when I remove it after being in place for 1-2 years). As well, any repair is considerably easier if an implant retained denture is provided. There is no doubt that a bar increases retention and resistance for a denture. However an implant retained denture can be a stable and viable option (upper or lower). This is especially if implants are placed parallel. This is nowhere near as difficult to achieve as it used to be if the surgical treatment is well planned and surgical guides are used and grafting (if required) is done. Having said this, new CADCAM techniques using milled bars (more vertical than older “free hand cast” designs) and various retention clip designs have reduced costs and increased stability tremendously. Even more recently, milled “shoe” frames (designed as additional support for the overdenture) have dramatically improved function even more (although it does add to the cost). CADCAM designed milled bars have dramatically reduced complexity of treatment and improved accuracy compared to cast bars. However I have experienced two problems. Firstly with locator retained dentures (including bars), there seems to be excessive wear on the locators in some cases. To be truthful I am not sure why this happens in some cases (although the incidence does seem higher in cases with excessive parafunction). However irrespective of bruxing, it makes no real sense to me that a metal locator should wear excessively when it is only in contact with a plastic denture insert. Due to this I have more recently been using stainless steel locators, or if the locators are on a bar, using screw on locators so they can be easily replaced (as opposed to welded locators). Of course there are other options to locators which can be considered. Secondly I find in a large number of cases, gingival hyperplasia occurs and fills in the space between the gingival ridge and the impression surface of the bar. This seems to be irrespective of the distance/space provided between the gingiva and the bar. The reason I allow space is to enable easy cleaning of the bar and most importantly the implants. Unfortunately hyperplasia reduces the cleanability. I am aware that the theory is that such hyperplasia only happens when there is poor oral hygiene but with my patients this is generally not the case. All patients have regular and thorough hygiene maintenance and are instructed in oral hygiene and are well motivated. I suspect it is more to do with no pressure or physical contact on the gingiva (due to shielding) or possibly a semi “vacuum” effect under a well fitting denture. The other issue to consider is the OVD. If there is not enough space then a bar (particularly a vertical bar) is not viable. So in considering what the best option is for a patient there are many variables to evaluate. If cost is the over-riding factor then a simple implant retained denture is probably the preferred option. If poor oral hygiene is an issue then an implant retained denture is the better option. However if excessive occlusal forces are involved then a bar retained over denture should definitely be considered. Of course there are many more alternative situations to consider on an individual basis. With all this said, I am tending to recommend an implant retained denture in preference to a bar over denture slightly more often.

Thank you Dr Gerke...I think the issue of gingival hyperplasia is very important and often ovelooked

Dear Dr. Gerke, This is a very good response to this question. Thank You.