Your 60-year-old patient has a long-standing bridge and she notifies you that the bridge is loose. When she comes in to the office you find one of the abutments has fractured at the gingival margin (Fig. 1).
Fig. 1: #7 fractured crown at the root
The crown/root ratio makes the root no longer a candidate for an abutment tooth. Your first thought is itâs time to extract the retained root and move to an implant
Fortunately rather than thinking only of the fractured tooth, you take a step back and take a full set of photos
Following FGTP for smile design you see the gingival margin was apical to the ideal smile line. It would be more ideal if the bone level is positioned more coronal, so the implant gingival margin will finalize at the preferred smile line.
The orthodontist can assist with erupting the teeth slowly so that the bone and the gingival margin follow. The path of eruption must be in a vertical direction. A fixed bridge presents some challenges to eruption with traditional labial braces (Fig. 2).
Fig. 2: The repaired provisional bridge with crown position labial to the fractured root
Often the teeth in a bridge have a proclined position and the extrusion will not produce the movement bone that is desired. The provisional bridge can provide anchorage for lingual
access to the retained root.
This case will demonstrate how the mechanics can be managed without using full fixed appliances. A wire with a loop end can be cemented in the canal so the loop is at the surface of the root. (Fig. 3)
Fig. 3: Wire loop placed in the canal
On the lingual incisal of the bridge a wire is bonded to the provisional edge out of the occlusion (Fig. 4).
Fig. 4: Wire bonded to the bridge out of occlusion. Elastic thread is connected
to the wire in the root. Note the vertical force direction by adjusting the loops.
A loop is in the wire directly over the root tip with the loop. Attaching an elastic thread the root can slowly be extruded behind the bridge in a vertical direction to ensure the bone follows. The rate of extrusion is .5 mm per month. The provisional may need to be trimmed at the gingival margin of the pontic if the root interferes as it extrudes (Fig. 5).
Fig. 5: As the root erupts, the wire is bent to keep the eruption force active
This usually remains hidden under the lip and poses a minimal esthetic
issue. The wire loop can be bent or trimmed to keep an active extrusive force level (Fig. 6).
Fig. 6: The bridge will need to be trimmed as the root erupts
Once the extrusion is completed, the root can be removed and an implant placed at the ideal bone height (Fig. 7).
Fig. 7: Final bridge and acceptable #7 gingival margin position
Ask your orthodontist to work with you on a treatment plan before you extract a terminal root fracture.
Donna J. Stenberg D.D.S., M.S., P.A. Spear Visiting Faculty and Contributing Author. [www.stenbergorthodontics.com
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