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SNB reflects how far forward the mandible sits relative to the cranial base. Functional appliances that hold the mandible forward during growth tend to produce skeletal changes, not just dental tipping, so the SNB angle increases when the mandible is guided to a more forward position and condylar remodeling occurs.

The Herbst appliance delivers a continuous, fixed forward position of the mandible, promoting forward growth of the mandible and remodeling at the condyle. This consistent forward guidance is why SNB typically increases with Herbst.

The Mandibular Anterior Repositioning Appliance (MARA) also keeps the mandible forward, encouraging skeletal adaptation rather than purely dental changes, leading to an increase in SNB.

The Twin Block uses opposing bite-blocks to posture the mandible forward; with growth and remodeling in response, SNB increases as the mandible assumes a more anterior position.

Other appliances may move teeth or cause variable skeletal effects, but their impact on SNB is not as consistently demonstrated as with Herbst, MARA, and Twin Block.