Making a pattern directly from patient’s mouth is indicated for an endodontically treated single root single tooth cast D&C restoration. The ideal shape of a direct pattern can be finalized in the patient’s mouth, and a direct pattern will be sent to commercial laboratory for casting. This same technique can be used for fabrication of provisional restorations for both direct pattern and indirect impression cast D&C fabrication techniques. The post component of the cast D&C direct pattern is fabricated using EZ post system (white compound and plastic endowel; Merritt EZ Cast Post Inc.) (Leong et al. 2009). The white thermoplastic compound is heated until it becomes clear color melted state. The plasticized compound is picked up with the plastic endowel and placed into the prepared canal of a tooth in the patient’s mouth. Once the material cools down to a white solid compound, the plastic endowel with the white compound is removed from the root canal (Fig. 11.5). If the removed white compound post has a void or is short from the orifice of the canal, additional melted compound is added, and post is placed back into the canal space to make a perfect post shape. Once the post portion of the cast D&C direct pattern is completed, the core portion of the direct pattern is fabricated using self-curing acrylic resin (Pattern Resin LS, GC America Inc.).

Once the endowel post is fully seated into the canal in patient’s mouth, the polymer and monomer of the pattern resin is applied around the plastic endowel using a sable brush. One must be careful not to drop monomer or polymer of resin into patient’s soft tissue. Once enough self-curing resin is applied around the endowel post and once resin is set, the core portion of the direct pattern is prepared using a diamond bur in situ. In case the direct D&C pattern is not stable during preparation, hold the pattern down in position using a periodontal probe. The core portion of direct pattern should be continuous from the remaining cervical portion of tooth structure, and no extra flash should be left. Remove completed one-piece direct D&C pattern to make sure that the core portion is well attached to the post section. If a vacuum shell preparation guide is available, try it over the core portion of the pattern to make sure that an ideal core shape is achieved. Once the core portion fabrication is completed to an ideal anatomy, a direct pattern of D&C is evaluated for its passive seating into the canal space. To reduce the chance of root fracture induced by cast D&C in the long term, the final cast D&C should seat passively without any friction to the axial wall of root dentin. Any white compound or red self-curing acrylic resin of direct D&C pattern engaging undercuts should be reduced using hot wax spatula and/or diamond bur until an absolute passive fit of direct pattern to the canal space is achieved (Fig. 11.6).

Set aside a direct pattern of D&C in a zipper bag to avoid misplacing it. One extra EZ post is created using the same technique to fabricate a one-piece provisional crown with EZ post. Once the post portion is fabricated, the handle of plastic endowel is turned into the nail head using a hot #7 wax spatula. Make sure that the white compound post with plastic nail head is seated fully in patient’s mouth and the putty matrix for the provisional crown is not interfering with the nail head. The provisional restoration material is applied into the putty matrix, and this matrix is seated onto the tooth. After setting, the one-piece provisional crown with EZ post is removed from the canal space. At this point, we should inspect the provisional crown to make sure that the junction between the provisional crown and the white compound post section is strong and seamless. In this specific case, an EZ post undercut engagement is desirable to gain additional retention for the provisional crown. This crown is cemented using a temporary cement. The cement is applied only under the crown margin, not around the EZ post, to ease the removal of cement from the canal space at a subsequent appointment (Fig. 11.7). Occlusion should be carefully adjusted and patient is dismissed. The direct D&C pattern is then sent to commercial laboratory for casting.

This impression technique of the prepared canal space is indicated for multiple teeth cast D&Cs or multiple pieces of cast D&C in a multi-rooted single molar. Making direct D&C patterns for multiple teeth in the patient’s mouth is not an efficient use of time. Also, if patient is pregnant or is allergic to self-curing acrylic resin, the indirect impression technique is indicated even for a single cast D&C fabrication.