Quiz 3 (Sessions 12-20) Flashcards
Define “Preparation” Step
Grind tooth circumferentially and on top
Why is a diagnostic wax up performed?
To idealize the tooth contours for the final restoration.
What does a provisional act as?
Prototype to test out the new contours for esthetics and function.
What is a by-product of condensation setting reaction?
Ethyl alcohol
What was developed to overcome the large polymerization shrinkage of condensation silicone impression material?
Putty
Define Biologic Width
The combined width of connective tissue and junctional epithelial attachment formed adjacent to a tooth and superior to the crestal bone.
How can the biological width be identified?
Probing to the bone (referred to as sounding to bone) and subtracting the sulcus depth from the resulting measurement.
What are examples of clinical situations where the crown margin is placed deep sulcus into the biologic width?
Removal of caries, placing margin on tooth structure instead of restorative material (like previous class V), subgingival tooth fracture and iatrogenic prep.
When is the biologic width violated or invaded?
When a margin is placed within the biologic width (junctional epithlium or connective tissue)
What two things can occur when the biologic width is violated?
Inflammation and bone loss`
What is one possibility for bone loss of an unpredictable nature along with gingival tissue recession?
Body’s attempt to recreate room between the alveolar bone and the margin to allow space for tissue reattachment.
Where is bone loss of unpredictable nature more likely to occur?
In areas where alveolar bone surrounding the tooth is very thin in width
_____ from restorative procedures can play a major role in causing this fragile tissue to recede.
Trauma
What type of tissue is more prone to recession?
Highly scalloped, thin gingiva
What type of tissue is not likely to recede?
Thick fibrous tissue
Two examples of clinical scenarios that cause a violation within biologic width
Removal of caries
Iatrogenic crown prep
What is invaded when the bur is carried in a straight line to connect the facial and lingual?
Biologic width
The ____ ____ follows the contour of the boney architecture that underlies and supports it.
Soft tissue
What are two ways to treat violation of biologic width?
Surgical crown lengthening
Rapid orthodontic extrusion
Describe surgical crown lengthening
Flap is reflected -> Bone is removed w/ bur or hand instrument -> Biologic width is reestablished after healing
How long does surgical crown lengthening take to heal?
Esthetic -> 4-6 months
When should the final impression be made after surgical crown lengthening?
4-6 months
Describe the crown and gingival margin after surgical crown lengthening
Gingival margin is moved apically
Incisal edge of tooth is the same height.
Describe rapid orthodontic extrusion
Tooth is extruded until the margin is moved out of the biologic width -> Bone fills socket as tooth is extruded
Describe the crown and gingival margin after orthodontic extrusion
Incisal edge is more apical than where it started.
Gingival margin is at the same height.
Which scenario gives the more favorable crown to root ratio? Crown lengthening or orthodontic extrusion
Orthodontic extrusion
Orthodontic extrusion crown:root ratio
1.25
Crown lengthening crown:root ratio
1.5
What three items establish papillary height?
Level of bone
Biologic width
Form of gingival embrasure
Changes in the shape of the ____ can impact the height and form of the papilla
Embrasure
The free gingival margin averages ___ mm above the underlying facial bone, the tip of the papilla averages ___ - ___ mm above the interproximal bone
3 mm
4.5-5.0 mm
Maxillary incisal edge display at rest ____ with age
Decrease
On average, ___ have greater incisal edge display at rest
Females
To establish the chemical bond between metal and porcelain, a controlled ____ ___ must be created on the metal surface
Oxide Layer
How is the oxide layer obtained
By placing the substructure on a firing tray, and raising the temp to a specific level that sufficiently exceeds the firing temp of the porcelain
What do manufacturers incorporate in casting alloy composition to form oxides and contribute to the metal-ceramic adherence?
oxies
What elements play a major role for porcelain adherence for high noble and noble metal alloys?
Iron, tin, indium and gallium
Example of glass ceramic
Feldspathic porcelain
Glass ceramic crowns are predominantly _____
Glass
Glass infiltrated ceramics are ______-filled glass
Particle
Example of Glass infiltrated ceramics (2)
Empress and e. max
Empress is made out of
Leucite
E max is made out of
Lithium disilicate
What type of cement should be used w/ emax
Resin cement
Three examples of polycrystalline ceramics
Alumina, Zirconia and emax (Zir-CAD)
What is the most translucent ceramic?
Glass infiltrated
What makes glass ceramics most esthetic?
High content of glass
What type of ceramic is the best at mimicking the optical properties of enamel and dentin?
Glass-ceramics
Describe Polycrystalline ceramics
Material with densely packed particles and no glassy components
What do polycrystalline ceramics need in order to process shapes
Use of computer assisted machining (milling)
Two characteristics of glass ceramic
Weak, transulent
Two characteristics of particle filled glass ceramic
Increase strength, less translucent
Two characteristics of polycrystalline
Strong, opaque
What are four classifications according to lab processing
Conventional feldspathic ceramics
Pressable ceramics
Machinable ceramics
Infiltrated ceramics
