Impression Materials - College of Dentistry - PDF

College of Dentistry ‫كليـــة طــب األســنان‬ Impression Materials Dr. Dawlat Mostafa Ahmed Assistant Professor of Dental Biomaterials Vice Dean of Educational Affairs College of Dentistry/El Alamein - AASTMT  Impression Materials Objective Understand the purpose if impression...

College of Dentistry ‫كليـــة طــب األســنان‬ Impression Materials Dr. Dawlat Mostafa Ahmed Assistant Professor of Dental Biomaterials Vice Dean of Educational Affairs College of Dentistry/El Alamein - AASTMT  Impression Materials Objective Understand the purpose if impression materials in the practice of dentistry. List the requirements of impression materials depending on the specific application. Classify the impression materials. Describe the composition, setting reactions and properties of: Non-Elastic impression materials. Elastic impression materials.  Impression Materials Contents Introduction of Impression Materials. Non-Elastic Impression Materials. Elastic Impression Materials.  I m p re s s io n d u c t io n o f Intro a ls M a te r i n M ate r ia ls t i f ic a t i o nf Impressio o M at e r ials Ide n s o f I m pres s i o n irem e nt te r ia ls I de a l R e q u re s si o n M a t i ons o f I m p C la s s if i c a  Impression Materials Introduction of Impression Materials Impression Materials Used to make an accurate replica of the oral tissues Impression Cast Give a negative The positive reproduction of reproduction of the oral tissues the oral tissues  Impression Materials Introduction of Impression Materials Impression Taking Impression Insertion Impression Trays Loading Impression Trays Impressions  Impression Materials Introduction of Impression Materials Types of Impression I. Primary Impression II. Secondary Impression (Final Impression) Stock Trays Custom made Special Tray Study Cast Master Cast Diagnosis and Treatment Planning Fabrication of the restorations Special Tray  Impression Materials Introduction of Impression Materials Question (1) What are the differences between primary and final impressions ?  Impression Materials Introduction of Impression Materials Ideal Requirements of Impression Materials Non-Toxic. Non-Irritant. Pleasant odor , taste and color. Easy to use. Adequate strength. Dimensional stability. Compatibility with model and die materials. Accuracy in clinical use. Readily disinfected without loss of accuracy.  Impression Materials Introduction of Impression Materials Classifications of Impression Materials Setting Reactions Ridge Undercut Classifications of Interproximal Undercuts Impression Materials Clinical Applications  Impression Materials Introduction of Impression Materials Classifications of Impression Materials 1. Hydrocolloids 2. Elastomers Impression Compound** Impression Plaster * Zinc Oxide Eugenol Paste * Waxes ** Irreversible Polysulfides * (Alginate) * Polyethers * * Chemical Reaction Reversible Silicones * ** Physical Reaction (Agar) **  st i c I m p r e s s i o n Non -E l a M a t e r i al s C o m p o u n d. Impression s i o n P l a ste r. Impres Pa s te. x i d e E u g e n o l Zin c O Waxes.  ate r i a l s s s i o n M Im p re c a t i o n s Cl a s s i f i Su p p l y s i t i o n s Co m p o c t i o n s Rea s e r t i e Prop Uses t i on s n i p u l a Ma  n C o m p o u n d Impre s s i o Impression Materials Non-Elastic Impression Materials Impression Compound Non-Elastic ( Thermoplastic ) 1. Classification Impression Material Impression Compound is 2. Supply available in Two Types Type I Type II (Low Fusing) (55-60 ºC) (High Fusing) Impression Materials Tray Materials Impression Materials Non-Elastic Impression Materials Impression Compound Mixture of …. Thermoplastic Resins and Waxes 3. Composition for (flow) Fillers (body) Coloring agent (Red..Rouge, Black and Green) Ingredient Parts Rosin 30 Couple Resin 30 Type I Carnauba Wax 10 (Low Fusing) Stearic Acid 5 Impression Materials Talc 75 Coloring Agent Appropriate Amount Impression Materials Non-Elastic Impression Materials Impression Compound Physical Reaction 4. Reaction Reversible Softening upon Heating 5. Properties a. Thermal Conductivity. b. Softening and Flow. c. Accuracy and Dimensional Stability. Impression Materials Non-Elastic Impression Materials Impression Compound 5. Properties a. Low Thermal Conductivity Upon Heating either by During Cooling inside the Immersion in Hot Water patient mouth or using Flam Time is needed for Time is needed for complete cooling of the complete softening of the whole mass whole mass Impression Materials Non-Elastic Impression Materials Impression Compound 5. Properties b. Softening and Flow Impression Compound Should Soften at a point just above Harden at the mouth the mouth temperature temperature Minimum Flow to reduce Adequate Flow to register distortion on removal from tissues surface details the mouth Impression Materials Non-Elastic Impression Materials Impression Compound 5. Properties b. Softening and Flow Flow Materials At 37 C ̊ At 45 C ̊ Type I Less than 6% More than 85% Impression Compound Type II Less than 2% 70-85% Tray Compound Impression Materials Non-Elastic Impression Materials Impression Compound 5. Properties c. Poor Accuracy and Dimensional Stability Release of Internal Stresses Thermal Contraction that produce upon Cooling from Warpage Mouth to Room Temperature (3%) Equally Important Adequate Flow during Softening Minimum Internal stress Impression Materials Non-Elastic Impression Materials Impression Compound 5. Properties a. Low Thermal Conductivity. b. Limited Flow at Mouth Temperature. c. Poor Accuracy and Dimensional Stability. Impression Materials Non-Elastic Impression Materials Impression Compound Type I (Low Fusing) 6. Uses Impression Materials Primary Impression for Completely Edentulous Patients Without Undercuts Impression Materials Non-Elastic Impression Materials Impression Compound Type I (Low Fusing) Impression Materials 6. Uses Border Molding  Impression Materials Non-Elastic Impression Materials Impression Compound Question (2) Think ?? Advantages and Disadvantages of Impression Compound  x i d e E u ge n o l Zin c O Im p re s s i o n Impression Materials Non-Elastic Impression Materials Zinc Oxide – Eugenol (ZOE) Impression Non-Elastic , Irreversible 1. Classification Impression Material ZOE Impression Pastes are 2. Supply supplied in Two Pastes System Base Accelerator (catalyst) Impression Materials Non-Elastic Impression Zinc Oxide – Eugenol (ZOE) Impression A. Base Materials Zinc Oxide (80%) Inert Oils (15%) 3. Composition B. Accelerators Materials Oil of clove or eugenole ………… (15%) Gum rosin and oils ……………….. (65%) Fillers (talc or kaolin) ……………. (16%) Magnesium chloride (accelerator)..(4%) Alternative of eugenole for sensitive patients Zinc Oxide and Chloro-thymol Impression Materials Non-Elastic Impression Zinc Oxide – Eugenol (ZOE) Impression 4. Setting Reaction Acid–Base Reaction (Chelation Reaction) Zinc Oxide + H2O Zinc Hydroxide Zinc Hydroxide + 2Eugenole Zinc Eugenolate + H2O (Chelate) Note: Water is essential for the setting reaction Impression Materials Non-Elastic Impression Materials Zinc Oxide – Eugenol (ZOE) Impression 5. Properties ZOE impression pastes: Produce a rigid impression. Adherence to the tissues. Provide good reproduction of surface details in thin section. Have good dimensional stability: 0.1% or less dimensional changes on setting. No significant further changes at the end of 24 hours. Stable on storage and have good life time. Impression Materials Non-Elastic Impression Materials Zinc Oxide – Eugenol (ZOE) Impression 6. Uses Final Impression for Completely Edentulous Patients Without Undercuts Impression Materials Non-Elastic Impression Materials Zinc Oxide – Eugenol (ZOE) Impression Question (3) Guess ?? How you can modify the setting time of ZOE impression pastes ? THANK YOU