Background: Eagle syndrome occurs when elongated styloid process or ossification of the stylohyoid ligament interfere with the surrounding anatomical structures giving rise to various symptoms. Watt W. Eagle identified two types: stylo-hyoid classic syndrome and stylo-carotid artery syndrome. The aim of this systematic review of the literature is to evaluate correlations between Eagle syndrome and traumatic events or teeth extractions. Methods: out of 294 articles, the final study allowed the identification of 13 studies focusing on traumatic events. Out of 342 articles, the final study allowed the analysis of two studies regarding extractive dental events. Results: 13 articles showed correlations between the onset of symptoms in Eagle syndrome and traumatic events and highlighted two possibilities: traumatic event could fracture the already elongated styloid process or calcified stylohyoid ligament; trauma itself triggers the pathophysiological mechanisms that lead to lengthening of styloid process or calcification of stylohyoid ligament and therefore the typical symptoms. The only two case reports concerning Eagle syndrome symptoms after extractive dental events describe the onset of classic type. Conclusions: The analyzed articles confirm correlation between traumatic event and onset of typical symptoms of Eagle syndrome. There is not enough literature linking extractive dental events to Eagle syndrome. Trial registration: CRD42020185176.

Background: This study is a systematic literature review aiming at identifying the variation of the average nasolabial angle (NLA) in various orthodontic situations. The NLA is one of the key factors to be studied in an orthodontic diagnosis for the aesthetics of the nose and facial profile. Methods: Out of 3118 articles resulting from four search engines (PubMed, Cochrane Library, Turning Research Into Practice (TRIP) and SciELO), the final study allowed the analysis and comparison of only 26 studies. These included studies have considered the NLA in the following cases: teeth extraction, class II malocclusion, class III malocclusion, rapid palatal expansion (RPE), orthognathic surgery, and non-surgical rhinoplasty with a hyaluronic acid filler. Results: The results indicate that teeth extraction and the use of hyaluronic acid fillers significantly affect the NLA. Conclusions: This systematic review shows that a statistically significant change in NLA values occurs in: extractive treatments of all four of the first or second premolars in class I patients; in class II patients with upper maxillary protrusion; in patients with maxillary biprotrusion, except for cases of severe crowding; and in patients undergoing non-surgical rhinoplasty with a hyaluronic acid filler. Trial registration number: PROSPERO CRD42020185166