Dowel (post) & Core 2023 PDF

4/19/2023 Lecture Topics… Dowels: Prefabricated or Cast Marjan Moghadam, DDS, MA [email protected] • Definitions • Prefabricated vs. Cast dowel • Post space preparation • Clinical pictures Definitions • Dowel: “A post usually made of metal that is fitted into a prepared root canal of a natural too...

4/19/2023 Lecture Topics… Dowels: Prefabricated or Cast Marjan Moghadam, DDS, MA [email protected] • Definitions • Prefabricated vs. Cast dowel • Post space preparation • Clinical pictures Definitions • Dowel: “A post usually made of metal that is fitted into a prepared root canal of a natural tooth. When combined with an artificial crown or core, it provides retention and resistance for the restoration…” Definitions • Dowel: …retains a core which in turn, retains a restoration GPT, 2008 Definitions • Primary purpose of a post is to retain a core – it DOES NOT “REINFORCE” the tooth • May help prevent coronal fractures when the remaining tooth structure is very thin after tooth preparation (Goodacre, 1994) Definitions • Pre-fabricated dowel – Pre-made dowel is cemented into a prepared canal space – Core added by using a restorative material 1 4/19/2023 Definitions • Pre-fabricated dowel – Pre-made dowel is cemented into a prepared canal space – Core added by using a restorative material • Cast dowel and core – Dowel & core are made from a resin pattern made intraorally – Sent to lab to be cast into metal Definitions • Not all endodontically treated teeth require dowel/core & crown – Anterior teeth – Assess amount of remaining tooth structure – Assess esthetics Indications • Amount of remaining tooth structure after removal of caries and previous restorations • Esthetics in anterior teeth • When more conservative retention and resistance features cannot be used for the core Pre-fabricated or Cast?? • Remove caries & previous restorations • Prepare the tooth for complete coverage • Remove any unsupported tooth structure • Decision made based on amount of remaining tooth structure 2 4/19/2023 Preparation • Length • Apical seal • Diameter • Shape • Surface texture • Ferrule Preparation: Length • As long as possible without affecting apical seal • Generally ¾ of the length of the root • Equal to or longer than the clinical crown Preparation: Length Length & Retention Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Preparation: Length • Initially, remove gutta percha with Gates Glidden and Peeso reamers Preparation: Length • Initially, remove gutta percha with Gates Glidden and Peeso reamers • Then shape the canal with the drill that comes with the system you are using 3 4/19/2023 Preparation: Apical Seal • Apical seal of gutta percha: – Keep 4-5mm at apex of tooth Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Preparation: Shape • Tapered v. Parallelsided – Parallel-sided is most retentive (Tjan & Miller, ‘84) – Create a keyway to prevent rotation Preparation: Diameter • Diameter should not exceed 1/3 of the root diameter at any location Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Preparation: Surface Texture • Roughened (knurled) is more retentive than smooth 4 4/19/2023 Preparation: Ferrule Preparation: Ferrule • Vertical axial tooth structure that will be covered by the crown • Minimum of 1.5-2mm, all the way around (360° encirclement) • Helps in fracture prevention • Crown lengthening or orthodontic extrusion if needed Preparation: Ferrule Preparation: Ferrule Preparation: Ferrule Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org 5 4/19/2023 Preparation: Ferrule Complications • Post loosening • Root fracture • Caries • Root perforation • Bent / fractured posts Complications • Post loosening • Root fracture • Caries • Root perforation • Bent / fractured posts Complications • Post loosening – Increase length of post – More parallel post – More intimate fit in canal Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Complications • Post loosening • Root fracture • Caries • Root perforation • Bent / fractured posts Complications • Root fracture – Increase length of post – More parallel post – Adequate ferrule Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org 6 4/19/2023 Complications • Post loosening • Root fracture • Caries • Root perforation • Bent / fractured posts Complications • Post loosening • Root fracture • Caries • Root perforation • Bent / fractured posts Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Complications • Root perforation – Increase length of post – Correct angulation – Correct diameter Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Technique • Prefabricated • Cast Complications • Post loosening • Root fracture • Caries • Root perforation • Bent / fractured posts Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Technique: Prefabricated • Crown preparation – Direct technique – Indirect technique 7 4/19/2023 Technique: Prefabricated • Crown preparation • Remove initial amount of Gutta Percha with Peeso and Gates Glidden reamers Technique: Prefabricated • Complete the core build up • Finalize tooth preparation • Fabricate provisional Technique: Prefabricated Technique: Prefabricated • Shape canal with system drill • Cement dowel Technique: Prefabricated • Integrapost System Technique: Cast - Direct • Complete crown & canal preparation • Plastic dowel is fit loosely in the canal Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org 8 4/19/2023 Technique: Cast - Direct • Complete core build up with resin Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Technique: Cast - Direct • Complete core preparation Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Technique: Cast - Direct • Send to lab for casting Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Technique: Cast - Direct Technique: Cast - Direct • Cement Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Technique: Cast - Indirect • Fabricate provisional Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org 9 4/19/2023 Technique: Cast - Indirect Technique: Cast - Indirect Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Cementation • Zinc phosphate – Standard cement, extremely successful, tried & tested • Polycarboxylate – Undergo plastic deformation, may lose retention • Glass ionomer • Resin-reinforced glass ionomer – Imbibes water, can expand with time Pictures Courtesy of Charles J. Goodacre, DDS,MSD Prosthopedia.org Protocol Available on Brightspace Fixed Prosthodontics Clinic site Final Thoughts • Prepare tooth first • Parallel-sided • Equal to or longer than the clinical crown • 4-5 mm apical seal of gutta percha • Rough surface • Adequate ferrule 10 4/19/2023 Marjan Moghadam, DDS, MA ~~ [email protected] 11