Which suture leaves more scarring: dissolvable or non dissolvable?

In my opinion dissolvable sutures produce the most scarring. The sutures dissolve by causing inflammation. This inflammation produces scarring.  

Long term - I think they are similar. However, in the short term a permanent monofilament suture like 6-0 Prolene creates the finest, most narrow and least inflamed facial scar. Sutures are usually removed between 5-7 days. For sutures placed under the skin, I usually prefer dissolving sutures as the inflammation created by their degradation isn't visible. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

Both dissolvable and non dissolvable sutures can be used with equal success closing skin.  The nature of the suture used will dictate when the surgery should be removed.  A non dissolvable skin suture is generally removed within 5 to 7 days of placement.  This can depend on the precisely nature of where the suture is placed.  So for simplicity, lets talk about the upper eyelid.  Any suture will induce inflammation.  Generally, permanent sutures like nylon or prolene are less inflammatory than absorbable suture.  The key is picking the right suture for the job and removing suture at the appropriate time.  Fast absorbing sutures made from gut disappear in about 6 days when kept moist.  Still the surgeon should remove whatever has not broken down at the end of this time frame.  Similarly, to avoid suture reactions, permanent skin sutures need to be removed also at the end of 5 to 7 days to avoid incision cysts and suture inflammation.  Longer term absorbable suture material such as chromic cut and vicryl basically act like permanent suture for the first few weeks and do not break down until many weeks later.  For this reason, these "dissolvable" sutures also need to be removed at the end of the 5 to 7 day time frame to reduce the risk of tissue reaction to this material.

I prefer the non-dissolvable, because those sutures are removed within a week. That leaves NO FOREIGN OBJECT in your skin. The dissolvable kind "dissolve" by stimulating inflammation. That can result in a longer healing period. Ask for non-dissolvable. 

but permanent sutures must be removed by a certain time after surgery (as determined by your surgeon) to prevent the stitch scars like Frankenstein's.  Dissolveable sutures cause reactions as they dissolve but they lumps usually go away.  Bottom line, the scar quality is often a reflection of the meticulousness of how the wound was closed and not what suture was used in closing.