How Well Do You Know Dental Prosthetics?

Dental Prosthetics: Classification, Impressions, Preparation, and Fixed Crowns

• The evaluation of teeth for prosthetics includes factors such as filling to dent pulp relationship, crown:root ratio, periodontium condition, and endo treatment quality.
• The Wild-Voldrich classification divides dent defects based on topography, transmission of masticatory pressure, size and function, and number and type of missing teeth.
• The I class of dent defects indicates restoration with dental, dentomucosal, mucodental, or mucosal transmission of masticatory forces.
• The II class of dent defects indicates restoration with mucosal, dental, mucodental, or dentomucosal transfer.
• The III class of dent defects indicates restoration with mucosal, dental, mucodental, or dentomucosal transfer.
• Alginate is an irreversible hydrocolloid impression material used to make a working impression in fixed prosthetics, mixed in a ratio of 1:1 by adding powder to water, and has good tear resistance.
• Silicones are hydrophilic impression materials with polydimethylsiloxane as the basic component, providing the most detailed impressions, volumetric stability, and can be cast up to 72 hours.
• Impressions in fixed prosthetics can be made with an individual or perforated metal impression tray, using a one-stage or two-stage technique, and an adhesive to prepare the impression tray.
• Impression trays are divided into prefabricated and individual ones, with sizes 1-3 (S-L) for adults, made of metal or plastic, and are universal for dentulous and edentulous upper and lower jaws.
• Pillars of the second class include upper lateral incisors, lower central incisors, upper first premolar, and lower second premolar.
• Basic preparation rules for prosthetics include preparation from frontal area to distal area, use of high-speed handpiece, proper centered and shape-appropriate diamond drills, and as many carbide drills as possible.
• For the preparation of occlusal surface, diamond bur needle, football ball, round bur, or carbide round bur can be used, reducing the occlusal surface by 0.5-2 mm while maintaining the original cusp-like shape. For frontal teeth, they are tilted vestibularly or orally during preparation, shortened by about 1/5 of the crown's length, and respecting the tooth's shape. The use of retraction cord is necessary for supragingival preparation, while full metal crowns require a circular reduction of 1.2-1.5 mm.