A

Schilder first articulated the mechanical objectives of root-canal cleaning and shaping—creating a continuously tapering funnel that follows the original canal curvature, maintains apical constriction, and preserves root-wall integrity; these principles are repeatedly cited as “Schilder’s mechanical objectives” in endodontic literature [Himel & Levitan, 2003, PMID 12723109; Sabala & Biggs, 1991, PMID 1810647].