Given the difficulty of getting primary closure, is it absolutely necessary to achieve full primary closure when using collagen membranes? Is slight exposure, OK? If not, what. kind of tips can you give for difficult cases to achieve primary closure?
The answer to this question will always depend on the nature of the procedure. Collagen membranes, in general, are kinder than other membranes when exposed, in terms of bacterial wicking and potential for infection. BUT, in any situation where real bone augmentation is aimed for (anything outside of an extraction socket), I think you need to achieve primary closure and maintain it to maximize success. Anything short of that risks compromising the final result.
In terms of tips for achieving primary closure I would say that you want to make sure there is adequate vestibular depth, keratinized tissue present, proper flap design, generous periosteal release, and tension relieving sutures. Each of these deserves its own discussion :-).
Your suggested video was very nice, dear Dr., but would be grateful for a more step by step detail while placing the said sutures, if possible.
Collagen is a protein that when exposed to saliva will disappear real quick. If exposure is likely or needed then a collagen membrane is not. Alternatives, depending on your regulatory region are:
Robert