Gingivitis is a widespread disease commonly associated with dentin hypersensitivity, that, in turn, may complicate routine dental care, leading to plaque accumulation. We aimed to assess the antigingivitis, desensitizing, and antiplaque effects of a fluoride-containing (TWF) alkaline toothpaste and a fluoride-free (TW) alkaline toothpaste. Eighty-four consenting patients aged 20–25 years with diagnosed gingivitis and dentin hypersensitivity (DH) were recruited in this double-blind, parallel-group study and randomly divided into two groups (each n = 42). Eighty-two patients completed the entire study protocol. The outcomes were assessed after 4 weeks of intervention. A significant improvement in gingival condition was found according to the modified gingival index, with effect sizes of 0.99 [CI95%: 0.52–1.46] and 1.71 [CI95%: 1.18–2.24], and the gingival bleeding index, with effect sizes of 3.17 [CI95%: 2.39–3.94] and 2.64 [CI95%: 1.96–3.32] in the TW and TWF groups, respectively. DH also decreased in both groups, with a significantly greater reduction in the TWF group (effect sizes of 3.28 [CI95%: 2.51–4.04] and 3.10 [CI95%: 2.40–3.80] according to the visual analog scale and Schiff scale, respectively). No side effects were registered. In conclusion, the use of alkaline toothpaste provided a significant reduction in gingival inflammation and bleeding, DH, and oral hygiene after 4 weeks of daily use in young adults. Trial Registration: NCT0562376. Funding: none.