ZYGOMA COMPLICATION – CASE ANALYSIS
Issues with implants can often be difficult to fix, and the more invasive nature and trajectory of Zygoma procedures adds another layer of complexity.
I have been corresponding with an OMFS colleague from US in relation to an issue with one of his cases. My colleague is chief of maxillofacial surgery at Veteran’s Hospital and has had excellent results for quite some time using Zygoma implants, and describes this complication as “new territory” for him, but the complication that he is encountering is unfortunately not all that uncommon with some Zygoma techniques and certain types of Zygoma implants, so I decided to share this case with my other audience/colleagues.
Below is the communication from my colleague:
I am sorry to hear that your favourite patient is having this issue. You must be so devastated and eager to try and do everything possible to fix it, but to treat this effectively you need to remove your personal attachment from the situation and assess it objectively.
This is a difficult problem to fix because the implant has a rough Ti-Unite surface. That surface is great when encased in bone, but not so great once contaminated and unfortunately all efforts to restore health will likely be frivolous for the following reasons:
(i) Sinus surgery by ENT surgery to drain the sinus and create additional drainage point could improve sinus drainage, but it will become reinfected because the cause (contaminated surface and micro movement of the implant) has not been removed. It will likely result in post-nasal drip and bad odours from mouth and nose and recurrence of the current issues.
(ii) Cleaning the area around the implant collar might improve the tissue health somewhat, but again, in the presence of the primary cause (contaminated surface and micro movement of the implant) this is not likely to be successful, especially considering the buccal overlap which can be difficult to clean.
(iii) Fat graft - this is really reserved for treatment of oro-antral communication and in the absence of significant infection or contamination. Neither of those conditions apply here so its not likely to make a difference and there is a slight risk to accessory branches of the Facial nerve
To resolve the issues you need to treat the primary causes:
Cause 1: MICRO MOVEMENT OF THE IMPLANT
It has been postulated that micromovement of the implant can occur due to a lack of secondary fixation, or when secondary crestal fixation is lost due to bone loss (as the case here). However, this is not typically an issue because of the rigid connection of the zygoma to the other implants. Nonetheless it can be an issue in this particular case because of the heavy bite. This can be reasonably simple to address with anti-clenching injections as per dosages below.
Cause 2: CONTAMINATED SURFACE
When the contaminated surface is accessible entirely from within the mouth it is worthwhile attempting to clean the collar of the implant and to expose more of the collar to allow better cleaning and maintenance eg when the Zygoma shaft is not fully within the sinus. In this case the shaft is fully within the sinus, so that won’t work without causing a large oro-antral communication.
Considering there is at least 20mm of the ti-unite shaft which is contaminated (which is a surface area of 2.5 sq cm) and the inaccessible nature of the shaft being well within the sinus, there will be no way to control ongoing recontamination.
To eliminate the cause I would consider removing the implant.
REMOVAL OF THE IMPLANT
The good news is that the patient has 5 other implants, which should be adequate to support a distal cantilever extending to and including the first premolar once the Zygoma support is removed. This will be adequate for function and not too much of a compromise aesthetically.
I would also reduce the cantilever in Quadrant 1 (remove one premolar and move the molar forward) - making the bite more anterior will reduce the triggers for excessive Masseter contraction. The loads can be further controlled with the anti clenching injections below.
The difficulty lies in the removal of the implant. There are no special kits available to remove the implant, and the trajectory through the sinus makes access to the lateral aspect of the integrated threads difficult. If it is integrated and cannot be removed with reversal, the only option is to access the threads by cutting the zygomatic bone on the lateral aspect to expose the threads and using smaller burs to release around the integrated surface. An elevator can then be used to detach the implant from the bone, and then it can be reversed.
The other alternative is to access the tip from the opposite superior and external aspect of the zygomatic bone, and then using a trephine to release the tip before reversing. A drill extension will be required for the trephine to bypass the thickness of the external tissue layers. Scarring can be minimised by following Langers lines.
Invasive procedures (other than removal of the implant) are not likely to be successful in fixing the problem.
There is no harm trying the most conservative approach:
Step 1 – generously cut back the buccal overlap to allow clear access to the collar of the implant for cleaning and flushing (must be a generous space).
Step 2 – administer anti clenching injections according to the protocol below.
Appointment 2 (1 week later)
Prescribe the following Medication and regime
DAYS 1-5 (5 days)
Doxycyclin 100mg (8am and 8pm)
Clindamycin 300mg (8am, 2pm and 8pm)
Pseudoephedrine 60mg (8am and 2pm)
Nasal Douche (8am, 2pm and 8pm)
DAYS 6-10 (5 days)
Continue as Days 1-5 PLUS add Prednisolone 25mg (8am and 8pm)
DAYS 1-15 (5 days)
Continue as Days 1-5 PLUS reduce dose of Prednisolone to 25mg (8am only)
Continue as Days 1-5
Appointment 3 (3 weeks later)
If the issues have not resolved, consider removing the implant and cutting back the bridge.
Once the implant is removed and bridge adjusted it may be sufficient and you may not need to do anything else.
If considering re-implantation, will need to wait 4—6 months and ensure sinus heath is restored. Once restored, you can consider re-implantation. My suggestion would be to use a smaller diameter implant with a polished collar positioned midway along the lateral wall of the sinus (slightly extra-maxillary) and anchored mor superiorly compared to the prior implant (lateral orbital rim). The ZAGA Flat Implant would be well suited for that, and you will get your access hole closer to the central fossa which will reduce the buccal overhang and cleanability.
ANTI CLENCHING INJECTIONS FOR ANY OF THE ABOVE OPTIONS
Below are the doses that I would recommend for this particular patient (based on the visible features) for the first 3 instances, and then drop by 10 units for subsequent instances:
60 units of Botulinum Toxin Type A (or 150 units in the higher dilutions) to each master and 20 units of Botulinum Toxin Type A (or 50 units in the higher dilutions) to each Temporalis at the most hypertrophic belly. This will need to be repeated every 3-4 months.