Arch

The dental arch refers to the curved, horseshoe-shaped arrangement of teeth within either the maxilla or the mandible. The maxillary arch, also called the upper arch, contains the upper teeth and is supported by the maxillary bone, while the mandibular arch, or lower arch, houses the lower teeth within the body of the mandible. Each complete adult arch typically contains 16 teeth, including incisors, canines, premolars, and molars, though the presence and number of third molars varies among individuals. The form and symmetry of the dental arches are influenced by genetic factors, skeletal development, and the functional forces of the tongue, lips, and cheeks that shape the arches during growth and development.

Arch form is a fundamental consideration in multiple dental disciplines. In orthodontics, achieving a harmonious arch shape that accommodates all teeth in proper alignment is a primary treatment objective. In prosthodontics, the arch form dictates the design of complete dentures, partial dentures, and implant-supported prostheses, as the prosthetic teeth must follow the natural curvature of the ridge to achieve functional occlusion and natural aesthetics. In periodontics, treatment is often planned and documented by arch or by quadrant, with the arch serving as the anatomical framework for organizing clinical findings. Irregularities in arch development, including narrow arches, asymmetric arches, or skeletal discrepancies between the upper and lower arches, create malocclusion that affects function, aesthetics, and long-term dental health.

In dental billing, the arch is a critical unit of service for numerous CDT procedure codes. Orthodontic treatment fees, complete and partial dentures, fluoride applications, and certain periodontal procedures are billed on a per-arch basis. Billing teams must correctly identify whether a procedure applies to a single arch or both arches, as submitting a per-arch code without specifying upper or lower can result in claim rejection. For prosthetic services, the arch designation determines the appropriate denture code, and billing for both arches requires separate line items. Accurate arch-level documentation in the clinical record ensures that claims reflect the correct scope of service and reduces the risk of payer audit findings related to arch-based coding errors.