Rebecca Boardman’s research while affiliated with University of California, San Francisco and other places

... Because of the close proximity of a labret flange (Figs. 2 and 3) with the dentition, dental wearor what some may describe as localized "damage" to teeth and oral tissues-is commonly associated with wearing perioral adornments. For instance, clinical literature repeatedly reports gingival recession in association with lip piercings, and some studies indicate that the severity of recession is influenced by the length of time the adornment has been worn and/or the position of the adornment relative to the enamel-dentine junction of the adjacent tooth (Boardman & Smith, 1997;Difloe-Geisert et al., 2024;Hennequin-Hoenderdos et al., 2016;Kapferer, Benesch, Gregoric, Ulm, & Hienz, 2007;Leichter & Monteith, 2006;Plessas & Pepelassi, 2012). Cracking, chipping, and localized atypical tooth wear (Plessas & Pepelassi, 2012;Vilchez-Perez et al., 2009) and tooth movement (Singh & Tuli, 2012) are also associated with lip piercings. ...

Reference:

Probable Use of Labrets Among the Mid Upper Paleolithic Pavlovian Peoples of Central Europe