1 / 5

Chapter 22

Chapter 22. Impression Materials and Laboratory Procedures. Impression Trays. Designed for obtaining an accurate impression of the area required, creates a model for diagnosing or the lab technician Tray selection: the dentist’s preference and what will provide the most accurate results

urian
Télécharger la présentation

Chapter 22

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 22 Impression Materials and Laboratory Procedures

  2. Impression Trays • Designed for obtaining an accurate impression of the area required, creates a model for diagnosing or the lab technician • Tray selection: the dentist’s preference and what will provide the most accurate results • Quadrant Trays (half arch), section trays (suited for anterior teeth), Full arch(cover the complete arch) • See Table 22-1, pg. 359, fig. 22-1

  3. Impression Materials • Impression is a negative reproduction of the teeth and surrounding structures, when poured up in stone or plaster it creates a positive reproduction of the teeth • Model is known as a cast • Three types of impressions: Preliminary, Final, Occlusal (bite). See Box 22-1, pg. 360, Fig. 22-2, 22-3, 22-4 pg. 360 also • Alginate: irreversible hydrocolloid, contains potassium alginate (derived from seaweed), calcium sulfate, trisodium phosphate, diatomaceous earth, zinc oxide, potassium titanium fluoride • Alginate has two physical phases: sol(material is a liquid or semi-liquid form), Gel( material becomes a semisolid • Two Types of Sets: Normal Set (2 min wt, 4 ½ min st), Fast set (1 ¼ min Wt, 1-2 min st) • Supplied in a powder form that is mixed with water 1:1 ratio

  4. Taking Alginate Impressions • Always be ready to mix the alginate, load tray, keep patient comfortable • Steps are to be taken to gain an accurate impression See Box 22-2, Pg. 361 • Always explain to the patient the procedure that: the material will be cold, no unpleasant taste, material will set quickly, breathe deep through the nose, do not talk after the tray has been placed • Diagnostic Casts: model that is made from impression • Model Plaster: not very strong, easy to trim, clean appearance, excellent for diagnostic, Fig. 22-6, pg 361 • Dental Stone: stronger than plaster, more durable, more for lab work fabrication

  5. Stone/Plaster Information • Have the same chemical formula, physical structures are different • Water to Power ratios vary for stone and plaster, can effect the setting time • Box 22-2, pg. 362 • Pouring Methods: double-pour, box and pour, inverted pour (differ because of the type of base) • Model Trimmer: used to trim cast stone/plaster models • Anatomic/art Portion of the Casts: fig. 22-9, pg. 363

More Related