Whaz up with this?
1 year ago by Steve Ratcliff | 12 Comments
What would you do differently?
These are photos from a patient I recently saw. His upper prosthesis is breaking down and the teeth keep breaking in the premolar areas on both sides. The prosthesis is an overdenture retained with passive clips over the bars.
He would like to know why the teeth keep breaking.
What are your thoughts? What would you have done differently?
With six implants, your patient has a wide variety of treatment options. If removable is breaking down, I would first ask how much acrylic is between the metal substructure and occlusal forces. It’s nice to have at least 2 mm for the strength of the acrylic. Another restorative solution would be to make a screw-retained metal-ceramic substructure and cement emax (full-contour pressed without porcelain additions) crowns on top. With up to 400 MPa of strength and high wear resistance, the final prosthesis will not break (hopefully) and will maintain VDO. If one tooth does break, the whole prosthesis would not have to be removed–just the one broken tooth would need to be prepared using standard crown and bridge techniques. Just a thought.
Hi Steve – I had a case very similar to this one. My patient was also wearing and breaking teeth. He was also wearing out the retention in the clips prematurely. We ended up changing to locators on the implants and remade the denture with a little more freedom in centric and it’s holding up much better. Whether it’s the increase in acrylic resulting in greater strength, I don’t know. I do know the retention is much better and the patient is very happy – so I’m happy! Hope all is well with you.
Not enough information. What’s on the lower? Force factors? Huge masseters? Bruxer? Sleep apnea? Obviously the prosthesis is getting hammered. Putting a longer fuse on the upper may not be the solution.
Would the patient accept a duplicate denture with flat occlusal surface (or with protrusive, lateral excursions support depending on the opposing dentition) that would play the role of full-arch splint? It would be interesting to see where would the mandibular teeth rest / occlude after few days of wearing it. If the occlusion scheme discrepancy between his original denture and the splint cannot be adjusted through equilibration, maybe a new denture would be the solution. Opting for stronger material in a different restorative solution might help …. for a while though.
There appears to be very little wear on the molars or #7-11. My guess is this prothesis is opposing lower natural teeth with a premolar occlusion. Fatigue fractures of the resin teeth are occurring due to inadequate distribution of occlusal forces. I like to have 3-4 posterior contacts on each side with a lingualized balanced occlusion. Maybe place lower molar implants if needed. If esthetics allow, open vertical to get thickness of acrylic and set teeth properly and we can keep this framework. Then equilibrate lowers to a flat plane. If we can’t open vertical, remove the bars and place Locators with a new denture. Thanks for throwing in a removable case. I’d love to see more of these from Spear Education. Most of my full mouth rehabilitations involve some form of removable prosthesis. It seems to be all folks can afford these days.
I would have placed the implants in the anterior because:
1. Sinus lifts could have been avoided.
2.A better quality of bone is found in the anterior.
3.In this case,the number of implants could have been reduced by at least two with similar or better retention.
4.If interior guidance were to be reproduced in the denture, this is where lateral forces would be applied thus stabilizing said forces.
5.This would allow for ample acrylic in the posterior lessening potential for stress fractures.
6.Axial forces would be applied to much thicker acrylic.
7.Undo pitch would be eliminated, lessening the exhaustion of clips.
If nocturnal bruxing is an issue, an orthotic over the implants could be a nice adjunct to this case. One or two implants placed in the anterior of this case could help stabilize it. Mini implants could even work well even if only used for diagnostics. If you choose to maintain the thickness of the current abutments, you could be screwed.
I’m not sure why he’s breaking teeth and his prosthesis but it seems to be the norm with these types of overdentures. I have never done one like this myself but have fixed plenty from other offices. Typically, I remove the bar, place locators, fabricate a new denture and things hold up much better. My guess is that the bar just makes things too rigid, which you can see because the teeth he is breaking are right over the bar. There is not enough support for the acrylic in these areas. This would be similar to a PFM crown that broke due to poor design of the metal coping. Ok. Just a guess. But in any case and from my experience, I would never make one of those types of overdentures.
It would be interesting to see if pre-treatment models were available in order to evaluate if there were any clues in the form of wear facets that would help define the movement patterns of the mandible. As described in the comments above, the current condition of the lower opposing dentition would be valuable information. I would use a technique that has been described for a complete removable upper denture opposing lower natural teeth where a recording medium of some type (such as auto-cure acrylic resin) is used to create a functionally generated occlusal pattern. Certainly, changing the occlusal surfaces irreversibly alters the existing prosthesis, and would require a careful discussion with the patient. The goal would be to make sure the occlusal surface of the denture teeth does not interfere with mandibular movement. Then I could evaluate if there was movement of the overdenture prosthesis related to the resiliency of the attachments — specifically if the denture was rotating around the axis created by what looks like two Swiss-Loc attachments in the premolar area with Bredent Vario Mini attachments certainly in the anterior and perhaps in the posterior segment. My personal preference is to avoid dental implants in the 8 & 9 area for dental implant supported overdentures as they limit my ability to modify the palatal contours for the /s/ and /th/ sounds unless they are used merely for a vertical stop or indirect retainer. Essentially, I wouldn’t feel comfortable proceeding with a new prosthesis without a little more information. This type of situation with a dental implant supported overdenture will likely become more common with time. Thank you for sharing, looking forward to more comments!
Well, I see pictures of the bars, and the prosthesis, but no pictures of the antagonist dentition.
I think we need to start there. What does the occlusion tell us?
Is the acrylic thin underneath the premolars due to the attachment apparatus? Or is there some sort of flexing of the denture due to the attachment placement? The only thing I can say I would have done differently is to talk to the lab about getting strong attachments and a strong denture before selecting the final product.
Not enough information. As you know we
Need the rest of the clinical data .
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