Chapters Chapters 46 Impression Materials 46 Impression Materials 47 Lab Materials and Procedures 47 Lab Materials and Procedures

Alginate Impressions Preliminary Impressions Preliminary Impressions Show teeth and surroundings tissue Show teeth and surroundings tissue Used for diagnostic aids Used for diagnostic aids Should fluff canister before using, (material settles and packs down) Should fluff canister before using, (material settles and packs down) Negative reproduction of the teeth and surrounding tissues Negative reproduction of the teeth and surrounding tissues

Rubber Base Final Impressions Final Impressions Most Accurate impressions Most Accurate impressions Measure equal amounts of catalyst and base material Measure equal amounts of catalyst and base material Homogeneous mix Homogeneous mix Catalyst incorporated into base when mixing Catalyst incorporated into base when mixing Elastomeric impression material Elastomeric impression material

Types of Trays Full Full Quadrant and triple trays Quadrant and triple trays Section (anterior) Section (anterior) Plastic/metal Plastic/metal Perforated/solid Perforated/solid Stock Stock Custom Custom Vacuum formed Vacuum formed

Ratio for mixing Alginate Maxillary—3 scoops of powder to 3 measures of water Maxillary—3 scoops of powder to 3 measures of water Mandibular—2 scoops of powder to 2 measures of water Mandibular—2 scoops of powder to 2 measures of water Too much water makes a thin mix and takes a long time to set Too much water makes a thin mix and takes a long time to set Too little water makes a stiff mix and set to quickly Too little water makes a stiff mix and set to quickly Plaster (gypsum product) Plaster (gypsum product)

Loading Alginate Trays Mandibular trays—two increments (one on each side of tray) Mandibular trays—two increments (one on each side of tray) Maxillary trays—one increment from the posterior Maxillary trays—one increment from the posterior

Removing Trays Mandibular trays—firm lifting motion Mandibular trays—firm lifting motion Maxillary trays—release posterior and then anterior Maxillary trays—release posterior and then anterior

Seating Trays Press posterior down first Press posterior down first Always explain to patient what you are doing Always explain to patient what you are doing Take mandibular impression first (patient will have better understanding of what is taking place) Take mandibular impression first (patient will have better understanding of what is taking place) Patient should be seated in the most upright position. Patient should be seated in the most upright position.

Seating Cont. Ask patient to swallow before seating tray, (this removes excess saliva and possible air bubbles) Ask patient to swallow before seating tray, (this removes excess saliva and possible air bubbles) Ask patient to lean forward when tray is placed. Ask patient to lean forward when tray is placed. Ask patient to breath through their nose Ask patient to breath through their nose Have patient lift feet off of chair, if they gag Have patient lift feet off of chair, if they gag

After removing trays Rinse patients mouth out Rinse patients mouth out Rinse with water and shake off excess Rinse with water and shake off excess Spray impression with disinfectant Spray impression with disinfectant Wrap in wet paper towel, if you can not pour immediately Wrap in wet paper towel, if you can not pour immediately Place patient’s name with impressions Place patient’s name with impressions

Pour Methods for Plaster Inverted pour – one large mix in single step Inverted pour – one large mix in single step Box pour – surrounded with box of wax Box pour – surrounded with box of wax Double pour – (fab mold)– anatomic first and art portion second Double pour – (fab mold)– anatomic first and art portion second

Setting Time Things that can affect setting time of alginate Things that can affect setting time of alginate Water temp—(warmer the water, the faster the set time) Water temp—(warmer the water, the faster the set time) Water to powder ratio (the more powder the faster the set) Water to powder ratio (the more powder the faster the set) Normal set or fast set alginate Normal set or fast set alginate

Dental Labs Most labs are in a separate area of the office, usually the back of office or the basement. Most labs are in a separate area of the office, usually the back of office or the basement. Well ventilated Well ventilated Items might include: Items might include: Model trimmers Model trimmers Vaccum formers Vaccum formers Lab burs and handpiece Lab burs and handpiece

Models Two portions of the cast Two portions of the cast Anatomic portion is created from the alginate impression, shows teeth and tissues Anatomic portion is created from the alginate impression, shows teeth and tissues Art portion forms the base of the cast Art portion forms the base of the cast Trimmed models Trimmed models Maxillary model will be pointed at the anterior portion Maxillary model will be pointed at the anterior portion Mandibular model will be rounded at the anterior portion Mandibular model will be rounded at the anterior portion Positive reproduction of teeth and surrounding tissues Positive reproduction of teeth and surrounding tissues

Bite Registrations Reproduction of the occlusal relationship of the maxillary and mandibular teeth, (when mouth is occluded) Reproduction of the occlusal relationship of the maxillary and mandibular teeth, (when mouth is occluded) Can be preformed or made in lab office Can be preformed or made in lab office