Temporary Crowns PDF - DHY8150 Dental Materials

TEMPORARY CROWNS DHY8150 Dental Materials Mrs. Barbara Seldon, RDH, RDA, MS Associate Professor, Retired Christela Falcon, RDH, MS University of Detroit Mercy School of Dent...

TEMPORARY CROWNS DHY8150 Dental Materials Mrs. Barbara Seldon, RDH, RDA, MS Associate Professor, Retired Christela Falcon, RDH, MS University of Detroit Mercy School of Dentistry Temporary Crown A crown preparation requires a layer of tooth to be removed from the crown of the tooth. Enamel and dentin is removed. Post and Core: There are times when so much tooth is broken down that the dentist has to build up the tooth with filling material first (make the tooth taller) before they complete the final shaping for the crown. Tapering Tooth: Besides reducing your tooth so it is smaller in size, the dentist must also shape the tooth in a specific fashion. A tooth receiving a dental crown must also be slightly tapered so the crown can FINISH LINE / GINGIVAL LINE / CEJ The finish line is a continuous edge that borders the entire preparation. The location is where the bur stops. It is essential that you have a mental image of the location and contour of a preparation’s finish line in relation to the gingival line and the CEJ in order to contour a temporary restoration for that tooth. Once the tooth has been shaped appropriately, the dentist will need to make an impression. The impression is a negative reproduction of the prepared tooth. The crown will be made from the impression.  The impression is a negative reproduction of the prepared tooth. The crown will be made from the impression.  A temporary crown will be placed over the prepared tooth until the permanent crown has been fabricated and returned from the dental laboratory. All Porcelain Crown The permanent crown is a positive reproduction of the  It takes approximately two separate appointments for a dentist to make a Permanent crown for a tooth.  Placing a Temporary Crown Purpose: Uses:  Reduce Sensitivity and discomfort  An interim or intermediate  Maintain function and aesthetics crown  Protect the margins of  A permanent the preparation crown for primary  Prevent shifting of teeth adjacent and opposing teeth Permanent Crowns for Primary Teeth  Types of Temporary Crowns  Custom constructed  Pre-formed acrylic  Pre-formed metal  Thin metal  Thin aluminum  Aluminum temporary Aluminum Crowns An Aluminum Crown is used most commonly on premolars and molars because of their resistance to wear, strength, and unaesthetic appearance. The chief advantage of this crown is its malleability, which allows for good occlusal adjustment. The softness of the alloy eases marginal and occlusal adaptation, as the material will stretch up to 50%. It can also be contoured and burnished without wrinkling. Softness, however, is the chief disadvantage of this crown. It can easily wear Preformed Aluminum Crowns  When a dentist prepares a tooth to receive a crown, the patient must wait days/weeks while the prepared impression is sent to the dental laboratory for fabrication of the crown.  In the interim, a temporary crown is placed over the prepared tooth to protect it until the permanent crown is cemented in place. Step I: Procedure The dentist prepares the tooth. The entire circumference of the tooth is reduced as well as the height of the tooth. Caries are removed and cavity medications are placed. (CaOH), Dycal is used to cover Step II: Selection The proper crown is selected. It must fit the circumference of the tooth It must fit the mesio-distal dimensions of the original crown of the tooth. Pre-formed Temporary crowns comes in a variety of sizes and shapes Step III: Fitting Occluso-cervical height must be adjusted so as not to extend more than 2mm below the free gingival margins. The aluminum crown is marked with an explorer and trimmed using crown scissors. The roughened edges created by the trimming must be smoothed  The aluminum crown is marked with an explorer and trimmed using crown scissors. The Margins of the temporary must fit snugly onto the preparation Crimping Pliers Contouring and crimping pliers are used to bend the cervical margins of the crown toward the tooth to assure a snug fit and proper cervical contour. Contouring pliers are used to smooth the crown after Step IV: Preparation An interim or intermediate restorative cement is used as a luting/cementing medium. It is usually Zinc Oxide and Eugenol temporary cementing medium. It is neutral in pH and has a sedative effect on the pulp. The powder is ZnO made up of Zn carbonate, ZN acetate, white rosin. The liquid is made of Eugenol, (Oil of Cloves). It Step IV Continues: The powder and liquid is mixed together on a parchment mixing pad or a cool glass slab. The mixing time is 8 minutes. Time may be accelerated with water. The powder and liquid react together to form Zinc Eugenolate. The Formula: H O + ZnO + Eugenol = Zn Step IV Continues A small amount of water is added to powder during manufacturing since zinc oxide completely dehydrated will not react with eugenol. The water reduces the shelf life and should not be purchased in large quantities. The addition of Rosin produces a smoother mix Eugenol contains 70% – 85% oil of cloves it is The Crown Fill the temporary Crown ½ full with The Zinc Oxide luting medium Excess cement splayed around the margins and must be removed. Knotted dental floss can be used to remove excess cement interproximally. Step V: Mixing Mixing medium today is “TEMPBOND” Mix it on a cool dry slab or parchment paper Watch demonstration on document camera  Temp Bond & Temp Bond NE With Eugenol Non-Eugenol Unidose Accelerator & Base Tubes Comes in Accelerator & Base tubes  Also comes in small packets (Unidose) Measure out equal parts  Mix the full content of the packets  Make sure mix is homogeneous Patient Instruction  Must return for the  Eat and chew as a permanent crown natural tooth  Potential for  Will last about 6 recurrent decay if months because of not replaced the weak luting cement  Brush just as if it is a natural tooth  Armamentarium Other items needed:  Aluminum Mouth mirror Gauze Crown Explorer  Cotton forceps or  Articulating paper Scaler  Ball burnisher  Dental floss Cotton  Knotted Rolls Temporary  Typodont Cement Parchment Paper Cement Spatula Scissors Contouring & Crimping pliers Temporary Crown Preparation Place the crown on the prepared tooth and align with the other teeth. Seat the crown on the prepared tooth and using an explorer, inscribe a trim line that corresponds to the Temporary Crown Preparation The crown is removed from the tooth. Using crown scissors, with the beak turned toward the contour line, trim the excess from the crown. After trimming, the margins should b smoothed with a green stone. Temporary Crown Preparation With crimping pliers, the marginal edge of the crown is crimped inward on itself. The crown is crimped at the last millimeter of the margin. Male portion on the inner surface of the crown. Crimping Temporary Crown Temporary Crown Preparation With contouring pliers the margins are smoothed inward and the ball beak of the contouring pliers is always placed on the inner surface of the crown to make smooth the crimping. Use an explorer to feel around the margins and check for discrepancies between the tooth and the margins. If large spaces are noted Temporary Crown Preparation Before After A snug fitting crown will produce a snapping sound as it slips into place. All surfaces and or margins must be smooth and free of voids. There must be visual contact with the adjacent teeth on the mesial and the distal surfaces. A ball burnisher may be used on the inner surface of the crown in the inter-proximal area to contour so that the adjacent teeth touch at the height of contour at the contact area. Check the occlusion with articulating paper. The temporary crown should contact the tooth or teeth in the opposing arch Cementation The prepared tooth is rinsed and dried thoroughly. Cotton rolls are placed in the buccal and lingual areas to maintain dry conditions. Mix the cement. The crown is filled with the cement and forced onto the prepared tooth. Cementation The crown is seated by having the patient bite carefully on it. Place a cotton roll on the line of occlusion and ask the patient to bite.  Removing Excess Cement Excess cement on buccal & lingual gingival margins Carefully remove excess cement with an explorer or scaler Evaluation  Crown Selection  Crown trimming  Crimping and contouring  Snug fitting  Contact with adjacent teeth  All surfaces smooth and free of voids  Excess cement removed  Hand articulate typodont in centric DOCUMENT CAMERA DEMONSTRATION