**5.1. The upper lip frenulum and its relation to the recurrence of diastema**

Some authors [15, 21] agree that orthodontic closure of diastemas caused by an abnormal labial frenulum, without subsequent brake removal surgery, greatly increases the frequency of relapse in the post-retention period.

Edwards [15] evaluated the relation of the abnormal labial frenulum with both the etiology of diastema and the stability of its treatment. In this study, the author concluded that frenectomy had a great contribution to increase the stability of the orthodontic treatment of the median diastema and commented, citing that the upper labial frenulum is one of the most relevant factors for the reopening of orthodontically closed diastema.

On the contrary, Shashua and Ärtun [28] did not consider the central labial cleft lip and fissure in the central interincisive bone crest as risk factors for diastema recurrence, after evaluation of diastema relapse 4–9 years after the end of treatment. The authors [28] observed that the presence of the abnormal brake at the beginning of the treatment influenced the initial width of diastema. However, they emphasized that this type of brake can remodel spontaneously with the closing of the space.
