  Tidal interactions between the embedded planets and their surrounding
protoplanetary disks are often postulated to produce the observed complex dust
substructures, including rings, gaps, and asymmetries. In this Letter, we
explore the consequences of dust coagulation on the dust dynamics and ring
morphology. Coagulation of dust grains leads to dust size growth which, under
typical disk conditions, produces faster radial drifts, potentially threatening
the dust ring formation. Utilizing 2D hydrodynamical simulations of
protoplanetary disks which include a full treatment of dust coagulation, we
find that if the planet does not open a gap quickly enough, the formation of an
inner ring is impeded due to dust coagulation and subsequent radial drift.
Furthermore, we find that a "buildup" of sub-mm sized grains often appears in
the dust emission at the outer edge of the dust disk.
