What is Partial Extraction Therapy (Episode 56 show notes)

In episode 56 of the Dental Digest Podcast Dr. Mark Bishara discusses partial extraction therapy (PET) or the socket-shield technique. This is a technique in implant dentistry in which the anterior portion of the root is left in the socket. This root becomes part of the osteotomy site (the site where you place the implant). This enables the final implant to achieve a more esthetic outcome.

Typically when the tooth is lost through extraction, the buccal bone resorbs away. This resorption occurs because once the root is extracted, the associated PDL and blood supply leave with the tooth. Once this is lost, the bundle bone (and then eventually the buccal plate) are lost. However, if part of the tooth can be maintained, the associated bone which would normally be lost, is retained. This “tricks” the body into thinking that the tooth is still there. Thus leaving some of the bone behind so a more esthetic outcome can be achieved.

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What are some of the shortcomings of PET?

This technique is fairly new so as a result there is a paucity of data to support it.

When is this technique particularly helpful?

PET is especially helpful when there are two adjacent implants to be placed. Typically when a tooth is extracted there is a neighboring tooth to still provide some bone. But, when you take out two teeth the bony architecture can become rather flat (and thus unaesthetic).

This technique is also incredibly useful when placing an implant in the esthetic zone of the mouth or if the patient has a thin tissue biotype. Oftentimes, in cases when a patient has a thin tissue biotype and the buccal plate is particularly thin, the implant can be seen through the gingiva with a bluish hue. With the use of PET, if extra bone is preserved (because the tooth is preserved) its possible that patients can be spared from having the implant see-through.

Why is this a helpful alternative to bone grafting?

Bone grafting is of course costly, time consuming and inconvenient for the patient. What’s more, grafts come with a risk of infection or failing to integrate. At times, their outcome can be unpredictable which can be especially problematic if the patient is esthetic-conscious. To complicate matters further, grafting the buccal plate can be challenging when there isn’t a pronounced defect to graft to. The benefit of PET is that it may make it so that a bone graft isn’t necessary.

What steps are involved in the technique?

PET is of course very complex, but here is a simplified explanation: first the crown of the tooth is sectioned and removed. Next, the buccal and lingual root are separated and the lingual root is removed. Finally, the implant is placed in the site.

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