Dental Materials DA122

 Two parts ◦ Anatomic portion  Created from the alginateimpression-the teeth ◦ Art portion  Forms the base of the model

Fig Anatomic and art portions of a dental model. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

 Double-pour method ◦ The anatomic portion of the model is poured first; then a second mix of plaster or stone is used to prepare the art portion.  Box-and-pour method ◦ The impression is surrounded with a “box” made of wax and poured as one unit.  Inverted-pour method ◦ One large batch of plaster or stone is mixed and both portions of the model are poured in a single step. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Fig Examples of pouring methods. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

 Prepare the model ◦ Soak it in water for 5 minutes.  Trimming the maxillary model ◦ Trim the base. ◦ Trim the posterior area. ◦ Trim the sides. ◦ Trim the heel cuts. ◦ Trim the angled portion from canine to canine (comes to a point between 8 + 9) (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

(Cont’d)  Trimming the mandibular model ◦ Trim the posterior portion of the mandibular model until it is even with the maxillary model. ◦ Trim the base. ◦ Trim the lateral cuts to match the maxillary lateral cuts. ◦ Trim the back and heel cuts. ◦ Trim from canine to canine in a rounded form. (Cont’d) Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

(Cont’d)  Finishing the model ◦ Mix a slurry of gypsum and fill in any voids.  Polishing a plaster model ◦ Soak the model in a soapy solution for 24 hours. ◦ Dry the model and then polish it with a soft cloth. Copyright © 2009, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.