Try using Locator attachments. We use these for denture retention for elderly patients. Two on mandible, 4 in maxillary arch. WB

Thanks

As I read this question it appears that the question circles around the clinical pick up of the male or female attachment (and housing) that is used with the overdenture. If this is the question I assume that the author is asking whether or not the intraoral pick up is more or less accurate then the laboratory orientation of the attachment.

As far as the accuracy of the two techniques, the clinical orientation will likely be more accurate than the laboratory orientation of the components. The reason for this is related to the compressibility of the soft tissue and the compressive force that is exerted when an attachment is connected intraorally in comparison to when the attachment is oriented in the laboratory. There are options for creating compressive force on the denture when you orient the component. One approaches to use finger pressure to hold the denture in place while the resin is setting. Another approach is to use biting force while the resin is setting. Neither of these is particularly well-controlled. If you are going to have the patient exert biting force with the teeth in maximum intercuspation you have to realize that it is very difficult to control the magnitude of force that the patient will exert. On the other hand if you hold the prosthesis in with your fingers you don't know what the occlusion will do once you release finger pressure and your ability to exert an amount of finger pressure is a bit of an unknown. In other words how do you control how much force you're going to exert on the denture? If we had objective measures to accomplish this there might be some benefit in this regard but then how do you equalize forces from the left side to the right side? It's not really easy and it gets more complicated when we realized that it's not just a right and left situation but it's an anterior and posterior situation. If you used in intraoral balancer that might allow a more centralized contact but the big drawback of an intraoral approaches always that it may or may not mimic nature and in fact it probably is unlikely to mimic nature because mastication does not occur at some centralize point, It occurs when the bolus of food is placed between the maxillary and mandibular prostheses which would be lateral and either anterior or posterior to the central bearing point.

So that's the biggest problem with the intraoral approach, The inability to establish bilateral simultaneous tooth contact that mimics the contact it is seen when the patient chews. The second problem with the intraoral approach is the issue of self curing resin and what happens to it over time.

The laboratory technique offers certain advantages relative to the avoidance of auto polymerizing resin which has a tendency to discolor overtime.

So if you're looking at tissue that is relatively limited in its compression it certainly is reasonable to consider the laboratory processing of the connector into the prosthesis at the time of prosthesis processing. If however the tissue is compressible and you process in the laboratory this will likely result in rocking of the denture over the components of the overdenture.

So if the tissue has a degree of compressibility you might want to consider is the clinical orientation of the components as the preferred approach. Many clinicians will have the patient utilize the denture for a few days without any retentive element in an effort to ensure that whatever minor seating occurs with the denture this seating will occur before the retentive elements are oriented to the prosthesis. This is the approach that I personally use but we have to realize that there is no absolute answer, If there was an absolute answer then we would probably all use the same technique.

Many of the attachments that are used have clinical spacers that'll allow a vertical range of movement before the component is fully seated. This is done in an effort to prevent the rocking that it was mentioned earlier if the components seat fully before the soft tissue compression is maximized. I think this is what most laboratories would use when they process the components into the denture. In essence the manufacturer has created an amount of vertical movement that can occur before rotation occurs around the written development.  

If you are using and approach whereby you do not want rotation around the implants and their respective components then the degree of vertical movement that is built into the retentive elements is a disservice rather than a service. Think of it this way, if you have a 4 implant supported maxillary prosthesis you will never have rotation around four points of contact because you can't align these implants in a perfectly straight line nor would you want to. So if you have four points of contact you are probably searching for a rigid connection to the implants that is a reversible connection in that you can remove the prosthesis. In that case the vertical freedom that is built into the attachment maybe working against you because now it allows a vertical movement of the prosthesis that is supposed to be essentially immobile.  If your goal is to have a rigid connection between the overdenture and the underlying implants, Three or more, then the laboratory processing would seem to make more logical sense. In that situation a processing, opponent that incorporates a degree of vertical freedom would actually be inappropriate because if there's a degree of vertical freedom there is a commensurate degree of vertical movement which works against the concept of rigidity which is what you are excepting if you put in more than one or two implants. Obviously with one implant you have rotation in all directions whereas if you use two implants you have rotation around a fulcrum line and if you have three or more implants you will not have rotation because three implants will not final line able to find a plane and you can't have rotation around a plane

This is a rather long answer to the question. Hopefully the question was one of whether or not the intro oral orientation is superior or inferior to the Laboratory processing. That is the way I read the question.

I guess one more point would be that in the mandible, Because of the smaller area of basal seat I anticipate the use of a two implant supported prosthesis with anticipated rotation around the fulcrum line while in the maxilla most would agree that more than two implants are necessary which then means that by necessity we are not looking at rotation. Taking this one last step further, in the mandible the technique would generally favor the clinical orientation of components while in the maxilla the technique would generally favor the laboratory orientation of components that do not have a degree of vertical freedom.

What is your opinion about chair-side pickup for mandibular or maxillary IODs. The technique in which the housings are incorporated onto the existing denture (maxillary or mandibular) and no lab steps are involved

The implant retained over dentures ? - ResearchGate. Available from: https://www.researchgate.net/post/The_implant_retained_over_dentures?tpr_view=GcKWHRov3uceihPlDF2jxuR13RtDvEQ8Q13U_2 [accessed Dec 21, 2015].

Chair-side intra-oral pickup is such a simple and time saving technique with good serviceability, I used it in a study to pick up O-ring attachments to the fitting surface of four implant retained maxillary over-denture while patients were biting in centric.

Article Effect of implant location on palateless complete overdentur...

ok Nesma, sounds good. thanks