W6 - Fixed partial dentures - DOWEL CORE RESTORATIONS Flashcards
What are the 3 types of fixed prosthetic appliances?
1.Extracoronal
2.Intracoronal
3.Intrradicular
What are 5 fixed extracoronal dental appliances that are not used for replacing missing teeth?
- Full coverage crown - endocrown
- Partial coverage crown
- Veneer: vestibular veneer, palatinal veneer, occlusal veneer - table top
- Splint
What are 3 fixed extracoronal dental appliances that are used for replacing missing teeth?
- Bridges
- Special bridges: winglike (extracoronal); inlay (intracoronal) retention bridges)
What are the fixed intracoronal appliances?
Inlay, Onlay and Overlay
What are the fixed intraradicular dental appliances that are not used for replacing missing teeth?
Indirect dowel core restorations
-Post and core
-Post
What are the fixed intraradicular dental appliances that are used for replacing missing teeth?
Direct dowel core restorations
- Metal post
- §Filler reinforced composite post
What are the indications of dowel core restoration?
*to retain restoration
*to protect remaining tooth structure
What are the contraindications of dowel core restoration?
- Anatomical malformations: severe curvatured root, short root
What are the 4 conditions of intraradicular restorations?
- Complete root canal filling
- Presence of minimally requested tooth structure which provides ferrule effect
- No periapical lesions
- Minimal length of the root is 8- 10 mm
DOWEL CORE RESTORATIONS PREPARATION - CORONAL PART
1. What are the Principles of tooth preparation according to Schillinburg?
- Preservation of tooth structure
- Retention and resistance form
DOWEL CORE RESTORATIONS PREPARATION - CORONAL PART
2. What are general principles of tooth preparation?
- Axial wall convergence (5–8°)
- Chamfer preparation / line of demarcation
- Avoid leaving behind very thin tooth stucture, sharp edges – special casts (epoxy resin or polyurethan)
DOWEL CORE RESTORATIONS PREPARATION - CORONAL PART
3. What is the question of undercut areas?
- Indirect posts - remove
- Direct posts - minimal invasive preparation, we can leave undercut areas behind
DOWEL CORE RESTORATIONS PREPARATION - CORONAL PART
4. What is Ferrule effect ?
Proper Ferrule effect is ensured when after preparation there is a sound circumferential coronal dentin tissue, which is 1-1,5 mm wide and at least 1,5-2 mm high (Attention: fiber reinforced posts)
DOWEL CORE RESTORATIONS PREPARATION II - ROOT PART
1. What is the order?
- Preparation of the root canal often comes before preparing the coronal part (e.g. we made the root canal filling before)
- Suggested to start with the preparation of coronal surface(not enough tooth tissue – revision of treatment plan)
DOWEL CORE RESTORATIONS PREPARATION II - ROOT PART
2. How should the environment be for the root part of dowel core restoration?
- Use a microscope
- Absolute isolation (rubber dam)
DOWEL CORE RESTORATIONS PREPARATION II - ROOT PART
3. What are the steps of root part of Dowel core restorations?
- Remove root canal filling
- thermal (elecrtic or heated endodontic hand instruments)
- mechanical (rotary devices and hand instruments)
- combination of the two - Controll x-ray of the cleaned canal (with a measured radioopaque instrument/guttapercha)
!!! Chemical way is not recommended for removing the root canal filling, because it can cause microleakage in the apical area.
DOWEL CORE RESTORATIONS PREPARATION II - ROOT PART
4. What are the general rules for post of root part of Dowel core restoration?
- At least 2/3 of the root length or as long as the clinical crown of the tooth (extralong root - 3⁄4)in case of indirect metal posts!
- 3-5 mm sound guttapercha apically * The post should be 4 mm lower than the alveolar bone crest
DOWEL CORE RESTORATIONS PREPARATION II - ROOT PART
5. What are the general rules for diameter of root part of Dowel core restoration?
- 1/3 of root diameter or less [each millimeter of increase in the post diameter (beyond 1/3 of root diameter) leads to 6 times more chance of tooth fracture*]
- We can start with Gates-Glidden or NiTi bur (carefully pulsating without water cooling, because of thermomechanical complications pl. frequent rinsing)
- Antirotation cavity
DOWEL CORE RESTORATIONS PREPARATION II - ROOT PART
6. What are the general rules for teeth with more roots of root part of Dowel core restoration?
- Distal canal of lower molars
*Palatal canal of upper molars - Question of split posts
What are the 2 types of Chairside direct posts, prefabricated posts?
- Metal prefabricated posts
- Fiber reinforced composite posts
What are the features of metal fabricated posts?
- temporary use
- Types: screw, granular,
serrated or totally smooth surface - Shape: convergent or relatively parallel posts, which are only convergent apically
- not esthetic because of metallic colour - fracture effect - special bur kits
What are the features of Fiber reinforced composite posts ?
- definitive use
- consists of two main materials (fiber and polimer martix)
- anizotrop material
- usually white, smooth surface
- cementation: adhesive technic,
rezin cement → monoblock system
- fiber: glass, polyetilen, silicate, carbon/graphite
or zirconium-dioxid
Why are there different stresses in the root dentin?
Different stresses in the root dentin caused by fiber reinforced composite post and metal post
What are the 5 questions of adhesive technique
- Compensation of the remaining tooth structure
- Proper planning and execution (stability of the post depends more on friction, than the strength of adhesive cementation)
- 2,5-3 mm high dentin tissue needed for proper ferrule effect (indirect metal post needs only 1,5-2 mm!)
- Pretreating post with silane or sand-blasting
- Wide root canal
What are the steps of cementation of fiber reinforced composite post?
1.Trying in
2.Building up with composite
3.Finsihing
What are the 2 types of Indirect posts are made in the dental laboratory?
- Post and core
- Post
How do we take impression for dowel core restoration?
Indirect ways - Conventional impression taking, digital impression taking
Direct ways - Custom made in the chair
