It depends on how much time the patient has been without teeth or prosthesis and if the stomatognatic system is balanced or not. 

It is the only unambiguous position to use as a starting point for interocclusal relations.  Any other position is a guess.

Mr Lawrence .... thanks for the input but sometimes it is impossible to achieve an RCP. What do we do then ?

We use intraoral gothic arch recording (Gysi system; with the Condylator or other one devices). Class III subjects tend to more posterior position, and class II subjects tends to the forward position of condyles. My profesional activity changed after the use of this approach; it is highly recommended.

Dear Dr. Rashid. Dr. Gettleman has given you a short, but correct answer.

Expanding a little, the concepts you use, ICP or Intercuspal position or the more accepted term Maximal Intercuspal Position (MIP) are contradictions in terms when making complete dentures, because in the edentate have no teeth or cusps that can contact - maximally or otherwise. A better term would be Muscular Contact position (MCP) which describes a primary contact between the jaws (via occlusal rims or dentures in the edentate) occurring when the unstrained mandible closes from its rest position. For the same reason, the other important term to keep in mind when recording the horizontal relation, Retruded Position (RP), would be a more precise term than RCP (Retruded Contact Position) in the edentate, because this position is guided by the relationship between the condyles and fossae at any one vertical dimension.

Leaving aside these somewhat hair-splitting and philosophical considerations, the RP is the only point of reference in an edentate person that can be reliably reproduced. Any attempt to record MCP is liable to show unacceptable variance and for that reason should not be used. For most patients the distance between RP and MCP is 1 mm or less. The possible discrepancy when constructing complete dentures based on RP is in my clinical experience rarely noticed by the patient. This is probably partly due to the visco-elastic quality of the denture supporting tissues and partly due to the limited stability of mainly the mandibular denture.

If the dentures are constructed based on a recording in RP, and one wishes an even occlusion in MCP, this can be accomplished by instructing the dental technician to grind in the occlusion in the articulator with the condylar balls advanced the appropriate amount (whatever that might be). Thus a so-called “Freedom in Centric” or “Long Centric” is established. Another method is to use denture teeth with low cuspal or zero degree inclines. Then the practical effects of the discrepancy between the two positions will be negligible.

Unfortunately, to my knowledge there is no science that indicates the usefulness of presence or absence of freedom in centric in complete denture cases. That of course means that one is left with the uncertain quality “clinical experience” and the above is a gist of mine – no more and no less.

The other question you raised is what to do if it is impossible to record RP. Again, based on my more than 40 years of clinical experience: difficult - certainly, but impossible - rarely if ever. A tense anxious patient, which is the rule rather than the exception in a dental surgery, is always difficult to treat, so the most important technique is simply to try to relax the patient, which again means using sufficient time for the recording. Trying to apply force gives rise to a counterproductive defensive mechanism although a firm, but gentle guidance backwards will usually get results. A technique that I have often found useful in difficult cases, despite the anatomical impossibility, is to ask the patient to “push the upper jaw forwards”.

In my hands, the more sophisticated and certainly more time consuming methods involving gothic arch recording suggested by Dr. Santana does not offer any advantages in difficult cases. At any rate, my advice is to try simpler methods first.

thank you very much

I agree with Einar Berg explanation.

Wow! "Push your upper Jaw forwards"! That sounds so useful and practical. I am adopting that straightaway. Thanks Einar Berg.

Dear Dr Amrore

If I really believed that the maxilla is movable, my Glaswegian BDS degree from 1963 ought to be rescinded (although it's a wee bit late for that now). The trick of asking the patient to move his upper jaw forwards is one that my old mentor FT Christensen taught me. I agree it sounds silly, but try it on a patient when you have problems recording PR before you pass judgement. If it doesn't work - at least you and your knowledgeable patient will have a good laugh! 

RCP is the only reproducible position for the edentulous patient. ICP position is dictated by the intercuspation of natural teeth, which does not exist in a completely edentulous patient. Another reason for mounting in CR is being able to do slight changes in VDO on the articulator without the need for a new jaw relation record. Hypothetically, if you use a facebow, and a CR record for mounting, then you can do those minor changes in VDO ,by moving the pin on the articulator, without introducing significant errors. 

My experience, based on many years of practice of removable prosthodontics, has led me to use a normal physiologic approach to achieving VDR, VDO and interdental arch spacing. It revolves around utilizing the patient's natural swallowing pattern, or exhaustive breathing technique and phonetic patterns which will use the patients muscle memory to record a quite accurate bite recording. This can then be tested with phonetics to establish correct tooth placement in the neutral zone. There are many other techniques that can be incorporated into the process to establish a physiologic position depending on the patient presentation. On difficult patients, especially those with debilitating diseases such as stroke victims or Parkinson-like patients  that prevents them from opening or closing in a normal fashion, the Gothic Arch Tracer is employed. It acts as a crutch for persons that have uncontrollable movements or debilitating muscle involvement and lets them rest on a fixed grid enabling the practitioner to establish a relative centric stop from which a bite plane is recorded and modified as necessary. I have explained in detail in my book "A Clinical Guide to Complete Denture Prosthodontics" the various ways I have used to achieve success in conventional denture prosthodontics. And, as with most problem solving in this area, there are various techniques that are utilized to achieve a good end result.

Thanks, information was very useful.

I have been using the Staub Cranial technique.  You need a lab familiar with the process and that has the jig for mounting the case.  The theory behind the procedure is to establish the vertical dimension by anatomic measurment of the triangle formed by the posterior Hamular processes and the anterior palatal foramen.  This when put into a mathematical equation gives the anatomical vertical dimension for the patient.  It is quite accurate and highly repeatable.  The case is then processes in a habitual occlusal contact position. I have used it for bite appliances, removable prosthesis, and fixed full mouth rehabilitation. All the cases that I have done have never had TMD consequences or problems with the final prostheses. 

Yes.

I have been blessed with the honor of teaching residents from all over the world and universally this is the norm. Our team has just completed a survey of the Academy of Prosthodontics on CR that we will be submitting for publication and 95% of the respondents would use CR for a reconstruction (both fixed and removable) of both arches. Ninety four percent of the respondents agreed that the apex of the gothic arch represented centric relation.

By definition, if a patient has lost all of their teeth their occlusal position is pathologic. The dentulous patient has CR, a PRP (physiologic rest position), an OVD (occlusal vertical dimension) and MI (maximum intercuspation) to work with while the totally edentulous patient has only CR and the PRP. While one could argue that the existing reconstruction/complete denture is in perfect MI and has an optimal OVD, one could counter with “why are you redoing?” There may be a few scenarios where this is present, but let’s keep to the more normal scenario and not the outliers, especially the neurologically impaired patient where a reproducible intra-oral record is a challenge.

To paraphrase Dr. Frank Celenza, CR is: reproducible, physiologically acceptable, eliminates retrusive considerations and it maintains eccentric control on the articulator and intra-orally.

The problem with CR is not if it is used, rather it is how you define and record it, both of which are too controversial to engage.

PS – will definitely try “push the upper jaw forwards”. Thanks Dr. Berg!