Anesthetize area. Take preliminary impression. Remove all defective amalgams and caries. Select gingival, body and incisal shades of teeth to be restored (NOTE: Best accomplished after old amalgam is gone). Calcium hydroxide is used over dentin in areas near pulp. Foundation build-up of glass ionomer-resin to eliminate undercuts is preferred to idealize preparation. Prepare teeth as follows: reduce facial, lingual and proximal surfaces a minimum of 1.2 mm (1.5 mm is preferable) allow for no more than 2.5 mm of incisal or occlusal reduction all line angles should be smooth and rounded insure there is an adequate path of insertion all gingival margins should be butt shoulder or accentuated chamfer Take a final impression with Panasil vinyl polysiloxane or similar impression material. Secure and trim an adequate interocclusal record (Regisil or similar material). Cement temporary restoration. Prepare detailed lab prescription with details re: opposing teeth, indicate the age and sex of patient and an indication as to the amount of occlusal staining required, as well as any individual characterization needed. Common Preparation Errors Insufficiently defined and finished preparation margins. uneven preparation limit ("gutter" preparation, vertical unevenness) irregular marginal reduction of layers (horizontal unevenness) wrong shape of preparation limit unnecessarily deep subgingival preparation preparation in root dentin Poorly controlled tooth reduction excessive reduction, especially in the upper anterior teeth (vestibular) and premolars. excessive incisal/occlusal reduction causing reduced retention and stability insufficient reduction at the palatal side of the upper anterior teeth (malfunction occlusion) excessive taper   Ideal Anterior Labial Surface Preparation with 1 mm depth grooves. Correct preparation of the labial surface of the tooth crown in two planes. Incorrect preparation of the labial surface: preparation in one plane; therefore insufficient reduction of substance. Due to an insufficient wall thickness of the crown, a fracture of the crown may result. Incorrect preparation of the labial surface: risk of damaging the pulp. Ideal Anterior Crown Preparation (Reduction of the labial and interproximal regions to pre-marked depth grooves) Ideal 3-Unit Anterior Bridge Preparation (In-Ceram Alumina only) Ideal Posterior Preparation (In-Ceram Alumina only) (Full Circumferential Shoulder 90º - 120º) Reprinted with permission of Vident. In-Ceram is a registered trademark of Vita Zahnfabrik. Return to In-Ceram® Crowns product page