Removable Prosthodontics - Science topic

Immediate, Delayed-Immediate, and Delayed implant placement: Which one is superior over the others? 

Is there any significant difference between them regarding primary stability, alveolar bone loss, and/or the success rate?

 ITI describes the immediate, early and traditional or conventional loading protocols. Are you talking about loading protocols or implant placement protocols relative to tooth removal?

Tooth extraction followed by implant placement (immediately or after a few months of healing) does not seem to result in any implant survival differences.  Most authors report a slightly improved been response if the implant is placed on the day of tooth extraction but this is often dependent upon the location in the dental arch.

Considering loading protocols there certainly is a difference in implant performance relative to loading protocol.  Of course there are factors that favor each protocol in different instances.  I suggest looking at the article by Gallucci et al that documents the consensus conference of ITI recommendations.  There is no straightforward simple answer.

Consensus statements and clinical recommendations for implant loading protocols. Gallucci GO, Benic GI, Eckert SE, Papaspyridakos P, Schimmel M, Schrott A, Weber HP. Int J Oral Maxillofac Implants. 2014;29 Suppl:287-90. doi: 10.11607/jomi.2013.g4. 

Hi Mohammed. I use the closed tray technique in the following clinical situations:

1. Single implants. 2. two non splinted implants (eg lower overdenture). 3.Limited mouth opening or implants located at the back of the mouth where long screws will not fit. 4. relatively parallel implants (no more than 2 though) and implants with their long axis parallel to the path of removal of the custom tray.

I use the open tray technique in the following clinical situations:

1. two or more splinted implants.2. implants with 15 degrees of divergence or more. 3.  immediate loading protocol.

Hope i answered your question sufficiently.Best regards.

This may be attributed to Costen's syndrome which is stated to be the result of prolonged over-closure and it consists of:

Mild catarrhal deafness and dizzy spells which can be relieved by inflation of the Eustachian tubes.

Tinnitus or snapping noise in the joint while chewing, and the affected joint may be painful, with limited or excessive movements.

Tenderness or dull pain while palpating over the affected TMJ.

Various neuralgic symptoms such as: burning or prickling sensation of the tongue, throat, or side of the nose.

Various forms of atypical head pain that refer to temporal region or base of the skull.

Dryness of mouth due to disturbed salivary gland function.

Regards,

Thank you.

An interesting  question about  a historic  approach . However,in my view,cross arch stabilisation is very much  yesterday's game.

There can be very little ,if any, justification now  for removing 62-73% of sound tooth tissue (Edelhof and sorenson 2002) for multiple preparations to provide one path of insertion for such prostheses.

The concept was founded on the   now discredited  idea that distributing  occlusal load across multiple teeth to provide rigidity  stopped periodontal disease.

Most of  have  not believed that for over forty years (Axelsson and Lindhe). Double abutting as a concept  can contain the seeds of  later failure due to pulpal or structural problems .Splinting teeth  for cross arch stabilisation also makes it more difficult for the average person to keep things clean -hence later failure.

Just ask yourself-"would I have that  destruction done to your own remaining sound teeth if you were missing those teeth"

The snap on smile used to be called a Hollywood bridge.  It was used for short term use and mainly as a diagnostic tool to determine if the future cosmetic result would be acceptable to the patient.  Unless it is acceptable , no further treatment is performed. Thus, the patient's mouth is not altered unless it is acceptable using a reversible diagnostic tool.

There are a variety of studies to support the feasibility of implant and tooth supported removable partial dentures

Clinical Outcome of Double Crown-Retained Mandibular Removable Dentures Supported by a Combination of Residual Teeth and Strategic Implants.

Rinke S, Ziebolz D, Ratka-Krüger P, Frisch E.

J Prosthodont. 2014 Sep 14. doi: 10.1111/jopr.12214. [Epub ahead of print

Unsplinted implants and teeth supporting maxillary removable partial dentures retained by telescopic crowns: a retrospective study with >6 years of follow-up.

Frisch E, Ratka-Krüger P, Wenz HJ.

Clin Oral Implants Res. 2014 Apr 16. doi: 10.1111/clr.12407. [Epub ahead of print]

Implant retention and support for distal extension partial removable dental prostheses: satisfaction outcomes.

Gonçalves TM, Campos CH, Garcia RC.

J Prosthet Dent. 2014 Aug;112(2):334-9

Implant Tooth-Supported Removable Partial Denture with at Least 15-Year Long-Term Follow-Up.

Mijiritsky E, Lorean A, Mazor Z, Levin L.

Clin Implant Dent Relat Res. 2013 Dec 27. doi: 10.1111/cid.12190. [Epub ahead of

Prognosis of implants and abutment teeth under combined tooth-implant-supported and solely implant-supported double-crown-retained removable dental prostheses.

Rammelsberg P, Bernhart G, Lorenzo Bermejo J, Schmitter M, Schwarz S.Clin Oral Implants Res. 2014 Jul;25(7):813-8.

Survival of double-crown-retained dentures either tooth-implant or solely implant-supported: an 8-year retrospective study.

Schwarz S, Bernhart G, Hassel AJ, Rammelsberg P.

Clin Implant Dent Relat Res. 2014 Aug;16(4):618-25.

Implant placement under existing removable dental prostheses and its effect on oral health-related quality of life.

Wolfart S, Moll D, Hilgers RD, Wolfart M, Kern M.

Clin Oral Implants Res. 2013 Dec;24(12):1354-9

Dental implants as strategic supplementary abutments for implant-tooth-supported telescopic crown-retained maxillary dentures: a retrospective follow-up study for up to 9 years.

Krennmair G, Krainhöfner M, Waldenberger O, Piehslinger E.

Int J Prosthodont. 2007 Nov-Dec;20(6):617-22.

Removable dentures with implant support in strategic positions followed for up to 8 years.

Kaufmann R, Friedli M, Hug S, Mericske-Stern R.

Int J Prosthodont. 2009 May-Jun;22(3):233-41; discussion 242

Use of dental implants to improve unfavorable removable partial denture design.

Mijiritsky E, Ormianer Z, Klinger A, Mardinger O.

Compend Contin Educ Dent. 2005 Oct;26(10):744-6, 748, 750 passim

I think it is important to remember that cantilevers have been used and continue to be used but we need specifics regarding the application that is being discussed.  

The simple formula of quantifying the distance from the fulcrum line to the anterior abutment on a bilaterally supported full arch prosthesis and multiplying this by a factor seems to be comforting.  Charlie English suggested the factor of 1.4 (this is the smallest factor so this is why it gets quoted) but if the frame is made of a weak material (Grade 1, 2, 3 or 4 CP Ti) this might be too much cantilever.  With 6-4 alloy it might work fine if the connectors are large enough.  

When Charlie talked about 1.4 x the world was simpler.  Frames were bulky and the veneer was resin.  Today we need to fill in a lot more blanks before offering an opinion and then we qualify so much that it sounds like there is no answer.  

I think Dr Freedman is correct, a suggested parameter is a good thing, we just need topic a parameter that is truly safe.  I like the English factor and look at it as a default but I still do Ti 6-4 alloy frames  and the anterior abutment to fulcrum line is usually long.  So for me the risk is frame fracture and know that a long cantilever (even if the formula allows) will take its toll on the integrity of the frame if overloaded because there will be a high stress at the connector to the terminal implant because of the lever arm (moment of force).

The initial polymerization contraction is 1.5-3.5%, which causes problems with bulk fillings shrinking away from margins, but has little effect on layered build-ups. Wear resistance and flexibility are built into the composite, but do not necessarily directly relate to polymerization shrinkage.

The FGP technique is not always the panacea. We are practicing different approaches for the last 20 + years and I can assure you that:

1. You will need a very distinct indication.

2. One registration approach does not fit all indications.

3. You need a very detailled understanding of occlusion.

4. Translation into prosthodontic work does not work with all materials and techniques.

5. You need an excellent lab technician.

I would like to endorse Steve's answer. In a developing country we have long waiting lists for patients requiring cost-effective RPDs and we have developed designs for acrylic-resin RPDs that follow the same principles as those with metal frameworks. Hence it IS possible to provide tooth support and with good guide plane retention, very often clasps can be avoided. In our opinion and experience, RPDs without tooth support are potentially iatrogenic. The so-called technopolymers and their flexibility make then unsuitable for RPDs. Like Steve, we have tried these but simply cannot make them conform to ANY of the basic principles of RPDs. Those we have seen being worn by patients (rarely by the way) are nothing more than gum strippers. So we do not advise using these materials!

I think that everything the Peter just said is absolutely correct.

The key in removable partial denture treatment is not in the technique but is in the constant reassessment of the effect of the differential between compressible soft tissue and relatively un-compressible hard tissue. An altered cast impression is a way to capture the compressible soft tissue in a more compressed state than it would be if you simply made an impression with a free-flowing material initially. The key is to be able to assess the clinical situation when the differential differentially applies forces to one structure (let's say the teeth) rather than another (let's say the tissue).

From my standpoint I'm not exactly sure what I would teach if I were teaching at the undergraduate level. At the graduate level in a prosthodontic graduate training program I would probably be a lot more aggressive in my expectations. My graduate students, over the years, have routinely done altered cast impressions. I think this is a skill that they must understand. More importantly however is the ability to determine when a reline is important because that becomes the procedure that protects the patient from the differential in compressibility.

Let's think about this a little bit. Our personal opinions are going to be based upon our own personal biases. Our biases are often dependent upon the clinical experiences that we have had. Indeed in this subject we have a few different categories of assessment of the occlusal vertical dimension. We often times assess this dimension on the basis of the vertical dimension of rest. The vertical dimension of rest is established through different techniques: radiographic, tactile, phonetics, aesthetics, etc. the vertical dimension of occlusion is usually some measurement closed relative to the vertical dimension of rest. It varies on the basis of skeletal jaw relationship with the largest differential being associated with a class II skeletal relationship in the smallest differential ring associated with a class III jaw relationship.

The reality is that we will never really be able to test this through a randomized controlled clinical trial. The reason for this is that an RCT is going to be influenced by the skills of the clinicians running the RCT. So if you have a clinician who is very good at the radiographic assessment of the analysis of the vertical dimension of Rest that individual may not be very good at assessing the tactile method of determining the vertical dimension of rest. Consequently the person who is experienced and skilled in the radiographic technique who then develops and RCT testing it against the tactile technique will undoubtedly find that the radiographic technique is superior. All the while another clinician trying to replicate the same results was experienced in the tactile technique would find opposite results. Remember that the RCT is an exquisite method of eliminating bias or reducing bias. The problem is that bias is not the only factor that relates to research evidence. We have issues of consistency, directness and precision. You might want to look at: http://effectivehealthcare.ahrq.gov/index.cfm/search-for-guides-reviews-and-reports/?productid=328&pageaction=displayproduct

So when you ask the question about our opinions on the best method to establish the clues of vertical dimension what you will receive is an answer based upon "our opinions" and those opinions are going to be very dramatically influenced by our experiences, our mentors, etc.

Ultimately I think that you need to, in my opinion, address this situation from a couple of different aspects. When I look at the occlusal vertical dimension I invariably use the tactile method and combine it with the phonetic method and combine it with aesthetics. After the cast are mounted I look at the parallelism of the ridges. I don't do electromyography and it is rare that I do radiographic assessment although I do this from time to time. So all this is important for me. It might not be of any relevance to you. The reality is that these are techniques and techniques are skill-based and experience-based, they will differ from clinician to clinician.

Fluid can not work so fast as chewing occurs. The deformed mucosal surface will not be ready for use in the next chewing cycle. Trauma and pain are the result of the slide and friction during denture destablization in the tilted position (with balancing contacts).

Please see:

https://www.researchgate.net/publication/233392646_The_influence_of_a_complete_lower_denture_destabilization_on_the_pressure_of_the_mucous_membrane_foundation?ev=prf_pub

Thanks to fluid, the area of tissue compression beneath a denture can be increased or pressure can be more evenly transfered . In the next cycle fluid must be ready for the next work. Only silicones are good in this case.

Moreover, the occlusal surface can vary during prolonged occlussion as the results of ongoing fluid flow ...

Thank you for your answer Dr. Shammas