Properly fitting aligners should cover the teeth and fit snugly against the patient’s teeth. They may feel a little tight at first.
- The aligner should usually cover the gingival by at least 1–3 millimeters (aligners may be trimmed differently to compensate for undercuts, black triangles, recession, bridges, etc.).
- The incisal edges of the teeth should fit flush against the aligners without any gaps
- The aligners should fit snugly over the distal surfaces of the rearmost molars if the aligner extends that far back.