Typically, periodontal scalers have pointed backs, but some new scaler designs have working ends with rounded backs as well.[4] Additionally, they have triangular cross sections; this limits their instrumentation use to above the gingiva (supragingival) to prevent any tissue trauma.[4] Periodontal scalers also have pointed tips and faces perpendicular to the lower shank; this is why the terminal shank must be tilted towards the tooth in order to establish correct angulation since the cutting edges are at equal levels with each other.[4]