Maintenance and Complications – Implant supported prosthesis
Maintenance and complications of the implant supported prosthesis is something we all must be aware of and paying attention to as the recommendations are likely to continue to evolve with new materials and new research.
How often should we remove the implant supported prosthesis?
“Removal of a fixed, screw-retained implant prosthesis for evaluation is not needed unless there are signs of peri-implantitis, a demonstrated inability to maintain adequate oral hygiene, or there are mechanical complications that require removal.” This is from the 2016 ACP position paper.
It is said by some that ideally the prosthesis will be removed once a year and have the screws replaced. I disagree and do not do it unless I see a need. However, there has been some research to suggest a re-tightening at 5 years. The loose screws in that study correlate to misfit prosthesis and since the study is old is likely from metal that was cast and may not be an issue with milled bars.
“I don’t take the prosthesis off unless I have a reason to do so. If I see thread exposure, inflammation, poor oral hygiene or any other reason. Screw threads will cross thread, you will find sometimes that you have created a problem that you other wise would not have created.” Howard C.
When removing there are multiple screws to check and verify
The MUA screw to the implant should be verified by either
- Placed to 35Ncm (if that is the recommended torque angled in particular may not be) and left for 15 minutes then rechecked
- Placed to 35Ncm and have return in 1 week to recheck
The prosthetic screw is often 15Ncm which is approximately hand tight.
Prosthetic issues for implant supported prosthesis
Gummy Smile or VME – Make sure get enough bone reduction! 13-15mm Use a clear duplicate denture guide at surgery time
Limited post space – Can hide with acrylic but makes less cleansable
Failure or implant – Mandible just replace and pick up if in temp. For maxilla replace but leave out of temp and adjust temp to all on one less than what you had
Men, bruxer, opposing natural or implant supported restoration consider extra implants.
Complications of the implant supported denture acrylic
Due to the fact that until recently this was not a very popular procedure, there is not a lot of long term data on comparing the different types of materials that can be used. To date this is one of the best studies, meta-analysis by Bozini
- All studies were on acrylic
- Almost all were external hex implants
- Most were in mandible
Complications for acrylic (keeping in mind the 3 bullet points right above this)
- Fracture rates 1/3 at 5 years, 1/2 at 10 years, and 2/3 at 15 years
- Screw loosening for both around 5-10-15% at years 5-10-15
- Screw fracture abutment 2-4-6% and prosthetic 4-8-12% at 5-10-15 years
- Framework fracture 3-6-9% at 5-10-15 years
- Wear 17-31-44% at 5-10-15 years
They also reported that resin veneer fractures were highest in the beginning of the clinical period; severe wear increased in the later stages of follow up. They noted that wear and veneer fractures were time related during the clinical course of the study. 1
Mayo clinic study with Salinas Dhima J Pros 2014
- 20 year survival 86% prosthesis
- 92% implant survival
- only 15% free of any event
If anterior teeth break out posterior support needs to be verified (could be reason for breakage) Kent Knoernschild
Staining can be an issue and if severe enough then use the Tiger Multi Mini polishing paste.
Maintenance and Complications – all ceramic implant supported prosthesis
Teeth will break when doing a frame with individual teeth. Malo shows 44% of patients experience this in the first 5 years.
Maintenance and Complications – metal ceramic implant supported fixed prosthesis
The survival rates of both implants and prosthesis are very high (above 98% at 5 year). However, there will be both biological and technical complications at high rates. Only around 10% of prosthesis will be either biological or technical complication free at 10 year. Most issues are either broken/chipped porcelain or peri-implantitis. Papaspyridakos JPD 2019
Cement vs screw retained full arch implant prosthesis issues are covered on another page.