A

Keratinized, tightly bound “masticatory” mucosa has a much higher pain threshold than the thin, mobile lining mucosa. Experimental algometer studies found that attached gingiva (and hard-palate mucosa) required several-fold greater pressure to evoke pain compared with buccal or labial mucosa, while the tongue tip was the most pain-sensitive area (Ogimoto et al., 2002, PMID 12153450; Svensson et al., 1992, PMID 1608647). Therefore the oral site with the least pain sensitivity among the options is the gingiva.