It is not a black-and-white rule that no sutures are used in dental surgery. There are disadvantages to suturing, e. g.:
Clinical disadvantages of suturing: Although suturing postsurgically
has many benefits, there are some disadvantages. Suture material that
is braided can often act like a plaque trap and soak up bacteria. This
is known as the "wick effect." (3) Bacteria in close adherence to the
wound site can cause infection and delayed healing. In addition,
breakdown products from the absorbable suture material itself have
been shown to cause an inflammatory reaction in the tissue in certain
cases. (4) The length of surgery may also be increased, since
suturing—especially in advanced cases—can be time-consuming and
technical. Studies have shown that any increase in surgical time can
also be correlated with an increase in the postoperative pain a
patient may experience. (5)
Source: https://www.perioimplantadvisory.com/clinical-tips/article/16412251/alternative-to-suturing-reduces-surgical-time-for-dental-procedures
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Ip HY, Abrishami A, Peng PW, Wong J, Chung F. Predictors of postoperative pain and analgesic consumption: a qualitative systematic review. Anesthesiology. 2009;111(3):657-677. doi: 10.1097/ALN.0b013e3181aae87a.