Mouth Preparation and Primary Impression PDF

Mouth preparation asnd primary impression Presented by Ahmed fayyad What is an impression ?? Negative reproduction of teeth and/or adjacent structures and from which a positive replica (cast) can be made Why ?? To produce a Cast over which a denta...

Mouth preparation asnd primary impression Presented by Ahmed fayyad What is an impression ?? Negative reproduction of teeth and/or adjacent structures and from which a positive replica (cast) can be made Why ?? To produce a Cast over which a dental restoration can be constructed What is a cast ?? a positive reproduction of the form of the tissues or teeth over which restorations may be constructed  Tissues Impression Cast  Patient Preparation Construction of a dentures should not be attempted unless the supporting tissues are in an acceptable condition. Existing Dentures – Old Dentures should be examined for fit and occlusion – If inadequate; can be corrected temporarily by Tissue conditioning material – Dentures should be removed from the patient’s mouth for 24-48 hours before making the impressions.  Tissue preparation/conditioning 1. Clinical examination 2. Correction of denture (over extensions, pressure areas, occlusion) 3. Application of tissue conditioning material 4. Oral hygiene instructions Healthy tissues ready for impressions 5. Tissue massage and rinse with warm water and salt 6. Remove denture at night Other considerations before making impressions Undercuts – Location – Impression material (elastic) – Blocking – Surgical correction if severe or bilateral Impressions for Complete Dentures Primary Secondary Impression Impression  Primary Impression Secondary Impression Stock tray Special tray Primary (study) cast Master cast construction of custom tray Construction of trial Alginate/impression denture base and final compound /Plaster of Paris denture Zinc oxide & eugenol/rubber base/ impression plaster  Stock tray Tray Custom tray  Ready made Different sizes and forms Allow adaptation : malleable material à bending Easily modified: – Allow addition of material – Allow cutting Allow 4-6mm for impression material over basal area  Check the tray size Adjust the tray: – Adding wax – Trimming border Stock Tray components Floor Body Flange (floor + flanges) Handle Tray For Dentulous Patients Tray For Edentulous Patients i. Floor upper lower ii. Handle iii. Flanges  Metal Non- Metal Aluminum, Plastic stainless steel Less modifications Easily modified Auto-clavable Disposable/auto-clavable  Perforated Non-perforated Alginate Impression Compound Full arch trays Sectional trays  Anatomical landmarks Peripheral areas or limiting areas Stress bearing areas or supporting areas Relief areas Anatomical landmarks in mandible Mandibular Limiting Structures § Labial frenum § Labial vestibule § Lingual frenum § Buccal frenu § Buccal vestibule Genial tubercles § Alveolo lingual sulcus Labial Vestibule § Retromolar pad Labial Frenum § Pterygomandibular raphe Supporting structures n Buccal shelf n Retromolar pad Relief areas n Crest of the ridge n Mylohyoid ridge n Mental foramen n Genial tubercles n Labial and lingual inclines n Torus mandibularis The sulcus is recorded All necessary landmarks are recorded Tray is centralized No voids Acceptable impression material mix Errors Pouring of Primary Impressions Primary cast is made to study: 1. Ridge shape. 2. Palatal Vault shape. 3. Denture bearing areas. 4. Areas of undercut. 5. Relief areas. 6. Posterior palatal seal area. 7. Sharp bony edges. 8. Depth of the sulcus. 9. Inter-ridge space. 10. Inter-ridge relations.  Constructed for each patient More accurate à why? Types – Acrylic resin – Shellac Borders 2mm short except? Adaptation Thickness Mix of material finishing