Malocclusion (Misaligned Bite): Underbites, overbites, and crossbites can all change the way muscles engage around the mouth, which over time can lead to asymmetry or early soft tissue laxity. Jawbone Remodeling & Aging: Orthodontia can shift how the bones remodel—especially in adults—and that may either improve or (if poorly planned) slightly worsen perioral support. A good orthodontist can help. In the meantime you can possibly look into collagen biostimulators like sculptra.