Modified digital cast technique for soft tissue management. A post-extraction implant placement case.
The aim of this case is to show how easy it can be to have full control of the an implant rehabilitation using a digital impression. Intra oral scanners are easy to use and they can be of great help in checking each phase. You can check thicknesses, occlusal prosthetic spacing chair side instead of checking these things in the lab a couple days later. This allows to carry out corrections and adjustments immediately, and then just re-scan the modified section.
The patient was referred to me because of the persistent pain the patient reported on tooth 21. After a trauma that involved both incisors – the patient is a goalkeeper
– both 11 and 21 had a root canal treatment and were splinted by means of a provisional bridge.
So we removed the provisional bridge to evaluate the situation and found a quite obvious vertical crack on tooth 21.
After also having assessed mobility of the fragments, the tooth was scheduled for extraction.
On the same session the tooth was extracted and we placed a 4×11.5 Anyridge implant (Megagen), with narrow core and large thread. The implant was placed 2 mm from the buccal ridge and 2 mm deeper than the CEJ of tooth 11.
In the occlusal view we can check the palatal positioning of the screw to maintain the 2mm of buccal bone that are vital for long term results in esthetic area.
An x-ray was taken to also verify that the distance from the proximal bony peak be safe enough to prevent losing the papilla fill.
An hole was made in the provisional 21 to check if the prosthetic axis was correct.
The provisional was then put its in position and the implant mount was inserted to better check the future implant emergence.
The ISQ value was 72, which means the implant was stable, but not enough for immediate loading. Moreover, because of the patient’s sports engagement, we decided that delayed loading was the safest option.
A corticocancellous heterologous bone mix was packed on the buccal and occlusal, in order to reduce tissue shrinkage in such an aesthetic area.
So the provisional on 21 was filled with resin and polished. The pontic will become an ovate pontic for soft tissue conditioning during the healing process.
After a 6-month healing period, the patient came back to remove the provisional bridge.
As you can see, the soft tissues were already mature, so we could proceed directly to the precision impression for the final crowns.
In order not to destroy the conditioned tissues by opening a flap, the implant platform was exposed by a 90° diamond bur under the microscope. This was also possible thanks to the conical connection of the implant, so we weren’t risking to jeopardising the integrity of the implant.
As we had to place a retraction cord and work on the abutment 11, we had to prevent the peri-implant soft tissues from collapsing. The trans mucosal site is know to contract by up to 60% in the first 20 seconds, so we quickly relined a regular transfer with some flowable resin.
In the picture you can see the scan body we used to take a digital impression.
The scan body was placed on 21 and the second retraction cord was left to sit on tooth 1. First we scanned the body on 21, and then removed the second cord and scanned abutment 11.
The .stl files were sent to the lab.
Thanks to any mesh viewing software, which is often included in a IOS dedicated software, you can measure the distance between the preparation and the antagonist. In this case we had less than 1 mm, so we had to exclude the porcelain fused to metal option. Together with MDT Daniele Rondoni we decided to fabricate a 1200 MPa zirconia crown with a buccal cutback to layer the feldspathic ceramic for optimum aesthetics.
I also received a preview from the lab of the crown before milling.
Thanks to the lab screenshots I was able to digitally superpose the project over the provisionals, which showed the project was canted. The lab was thus able to change the design before milling.
We transferred all into the milling software.
The monolithic full zirconia implant-screwed crown was cut back without even having a model.
The try in was good, so we decided proceed to layering the ceramic layering.
The final restorations were also checked with an x-ray. Note how precise both crowns are.
The final restoration by MDT Daniele Rondoni shows a very natural integration of the white/pink transition area.
Digital impression devices are today trustworthy and accurate, we just need a correct workflow.
The overall desired tissue stability was achieved, together with a natural and aesthetically pleasant appearance.
In post extraction implant placement, filling with heterologous bone is of great help in maintaining tissue volume and prevent shrinkage.
The ideal position was respected, and an ovate pontic was fabricated to condition the soft tissues during healing. This was money and time saving for the patient.
Last but not least, the digital cast tecnique was helpful to maintain the tissue and avoid contraction and to accurately replicate the shape of the gum, the same could be done with the temporary crown in case of an immediate loading.
So, if you use a correct digital workflow, you can trust scanner accuracy.
Moreover, you have no cast delivery, easy control over occlusion, no transfer sent, just an email. The scan body can be used for many patients without waiting for the lab to return it. And, last but not least, a digital design preview is easy to send and to check, before having to deal with physical modifications and do-overs.
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