Indirects Flashcards
(21 cards)
Advantages and disadvantages of inlays onlays
Advantages
Superior materials and margins
Won’t deteriorate over time
cuspasl coverage (onlay)
Disadvantages
Time
Cost
What is an onlay prep
Flat pulpal floor, 4-6 degree taper, no undercuts, butt joint cavosurface margins, clear contact points, rounded angles
Occlusal reductions:
Porcelain
-Non working cusp – 1.5mm reduction
-Working cusp – 2mm reduction
Gold
-Non working cusp – 0.5mm reduction
-Working cusp – 1mm reduction
Margins:
-Porcelain – 1mm shoulder or chamfer
-Gold – 0.5mm chamfer
Advantages and disadvantages of crowns
Adv
Protect a weak or damaged tooth
Improve the appearance of a tooth
Pain relief
Long-lasting
Improved chewing and speaking
DisAdv
Reduction of dental enamel
May need to be replaced
Possibility of Nerve Damage
Dental sensitivity
Maintenance
What are the crown preps
Ceramic (zirconia etc)
2mm functional cusp reduction
1.5mm non-functional
1-1.5mm Chamfer
MCC
2mm functional cusp reduction
1.5mm non-functional
Chamfer 0.5-1mm lingual/palate
shoulder 1.5mm buccal
Anterior ceramic crown
Incisal reduction 1.5-2mm
Labial lingual reduction 1-1.5mm
1mm chamfer
Indication for veneer
Aesthetics (enaml defects, staining)
fix peg laterals
Change teeth shape and colour
reduce diastemasz
Contraindication for veneers
Poor OH
High caries rate
Interproximal caries and/or unsound restorations
Gingival recession
Root exposure
High lip lines
If extensive prep needed (>50% of surface area no longer in enamel)
Labially positioned, severely rotated and overlapping teeth
Extensive TSL/insufficient bonding area
Heavy occlusal contacts
Severe discolouration
What is the veneer prep
0.3mm cervical reduction chamfer
0.5mm midfacial reduction
1-1.5mm incisall reduction
What to right on a veneer lab sheet
Lab prescription
Pour impressions
Mount casts
Articulator
Waxbite
Occlusal record – e.g. JetBite
Facebow
Construct restoration
Tooth (FDI notation)
Material
Thickness
Characteristics
Shade
Translucency
What to write on a crown lab sheet
Lab prescription
Pour impressions
Mount casts
Articulator
Waxbite
Occlusal record – e.g. JetBite
Facebow
Construct restoration
Tooth (FDI notation)
Material
Thickness
Characteristics
Shade
Indications for bridgework
Function and stability
Appearance
Speech
Psychological reasons
Systemic disease e.g. epileptics
Co-operative patient
Big teeth
Heavily restored teeth
Favourable abutment angulations
Favourable occlusion
Contraindications for bridges
Uncooperative patient
Medical history contra-indications
Poor oral hygiene
High caries rate
Periodontal disease
Large pulps (conventional bridge)
High possibility of further tooth loss within arch
Prognosis of abutment poor
Length of span too great
Ridge form and tissue loss
Tilting and rotation of teeth
Degree of restoration (how much of tooth is left after preparation)
Periapical status
Periodontal status (bone loss)
Adv and DisAdv of RBB
Minimal or no preparation
No anaesthetic needed
Less costly
Less surgery time
Can be used as a provisional restoration
If fails - usually less destructive than alternatives
DisAdv
Rigorous clinical technique
Metal shine-through
Chipping pocelain
Can debond
High chance of it debonding again
Occlusal interferences
No trial period possible
Indications for RBB and Contrai
Young teeth
Less destructive
Good enamel quality
Large abutment tooth surface area
Minimal occlusal load
Good for single tooth replacement
Simplify partial denture design
Contrai:
Insufficient or poor quality enamel
Long spans
Excess soft or hard tissue loss
Heavy occlusal force e.g. Bruxist
Poorly aligned, tilted or spaced teeth
Contact sports
What is bridge prep if needed for post and ant teeth
Post:
180º ‘wrap-around’ preparation
Rests -Rest seats (posterior teeth) ,Cingulum rest (anterior teeth)
+/- Proximal grooves
Supra-gingival chamfer finish line ~0.5mm
Ideally prep should remain in enamel
Ant:
Cantilever design
No preparation
Minimal preparation
Occlusal contact reduction,
Cingulum undercut removal only
Chamfer margin (0.5mm supra-gingival)
Heavier preparation
0.5mm palatal reduction (NOTE – metal retainer wing should be 0.7mm thick)
Cingulum rest
+/- Proximal grooves
Chamfer margin (0.5mm supra-gingival)
Conventional fixed fixed Adv and DisAdv
Adv
Robust design
Maximum retention and strength
Abutment teeth splinted together ? (Perio cases with mobile teeth)
Can be used in longer spans
Laboratory construction straightforward
DisAdv
Preparation difficult (parallel tooth preparations needed)
Preparation must be minimally tapered
Common path of insertion for abutments
Removal of tooth tissue (danger to pulp)
Conventional cantilever Adv and DisAdv
Conservative design
Compared to fixed-fixed conventional design
Laboratory construction straightforward
No need to ensure multiple tooth preparations are parallel
DisAdv
Short span only
Rigid to avoid distortion
Mesial cantilever preferred
When to use what pontic design
Wash through- lower posterior
Dome shaped- Lower incisors, preM, upper molars (DONT USE IN HIGH SMILE LINE)
Modified ridge lap- Mod to low smile line anteriors
Ridge lap- Long span anteriors, High smile line anteriors
Guidlines for posts
Tooth type
-Incisors and canines - post unnecessary if sufficient coronal dentine is present
-Avoid in mandibular incisors due to thin/tapering/ narrow mesiodistal roots
-Premolars - If a post is to be placed then place in the widest root canal
Root filling length
-4-5mm root filling apically
Post width
-No more than 1/3 of root width at narrowest point and 1 mm of remaining circumferential coronal dentine
Sufficient alveolar bone support, at least half of post length into the root
Minimum 1:1 post length/crown length ratio
Ferrule
-At least 1.5mm height and width of remaining coronal dentine
What is ideal post
Parallel sided
Avoids ‘wedging’
More retentive than tapered
Non-threaded (Passive)
mooth surface incorporates less stress to remaining tooth than threaded (Active)
Cement Retained
Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/too
Adv and DisAdv post types
What to right bridge prescription
