Tx planning for fixed prosthodontics Flashcards
What is fixed prosthodontics
• The area of prosthodontics focused on permanently attached (fixed) dental prostheses
What are the different types of fixed prosthodontics
○ Veneers ○ Inlays and onlays ○ Crowns ○ Bridgework ○ Cores and posts are an in between of fixed prosthodontics and endodontics
What does the history and examination consist of
patient complaint history of presenting complaint past dental history past medical history social history family history extra oral examination intra oral examination
What does an extra oral examination consist of
TMJ muscles of mastication lymph nodes symmetry lips
What do we look at in the lips
vermillion borders
commissures
smile line
Why is the smile line so important
as a lot of fixed prosthodontics is aesthetically driven and we want to make sure the teeth fit the patients face shape and lip shape
Describe the different smile lines
□ The smile line goes from high to low
□ A high smile line means you can see a lot of the teeth and the gingiva
□ A normal smile line you can just see the interproximal gingiva
□ A low smile line is ideal for fixed pros
What do we look at in an intra-oral examination
look at the whole mouth before looking at individual teeth
soft tissues periodontal dentition occlusion inter arch space inter tooth space
What soft tissues do we look at
buccal mucosa tongue sublingual tissues/floor of mouth palate lips
How do we look at the periodontal health
BPE
How do we look at the dentition
□ Chart teeth
® Present and missing teeth
® Restorations
Caries
What do we look at for the occlusion
□ Incisal relationship □ Excursions of the mandible ® Protrusion ® Retrusion ® Lateral □ Canine guidance □ Group function
What special investigations can we take
sensibility testing radiographs study models face bow diagnostic wax up additional
What are the radiographs for
○ Caries - is the tooth restorable?
○ Any tooth fractures?
○ Any periapical pathologies?
○ Are the bone levels ok? Are the teeth adequately supported? Are the teeth mobile?
○ Look at the existing large restorations
○ Assess the potential abutment teeth
What is the face bow
It is an instrument that records the relationship of the maxilla to the hinge axis of rotation of the mandible and it allows for the transfer of both aesthetic and functional components from the patient to the articulator
What does the face bow allow
○ Allows you to look at the occlusion
○ Allows you to see the guidance and is important for if you are placing restorations on teeth that are involved with guidance
What are additional special investigations
○ Diet diary ○ Plaque and gingivitis indices ○ Full mouth periodontal chart if the BPE is coming back as 4 ○ Clinical photographs ○ Microbiology, biopsy, haematology
What are the 5 stages of Tx planning
immediate initial (disease control) re-evaluation reconstructive maintenance
What happens in the immediate phase
○ Relief of acute symptoms
○ Consider endodontics and extractions
○ Consider immediate denture/bridge
What happens in the initial phase
○ Extraction of hopeless teeth
○ OHI and dietary advice
○ Hygiene phase therapy (perio)
○ Management of carious lesions and defective restorations with direct restorations or provisional restorations
○ Endodontics
○ Denture design, wax up for fixed prosthodontics
§ Good to have the initial design that you can follow through with if the patient is compliant and improves oral health
What happens in the re-evaluation stage
Re-assessment of periodontal status, confirm denture/bridge design
What happens in the reconstructive phase
○ Perio surgery
○ Fixed and removable prosthodontics
At this stage we wont have any active disease so our restorations can be as successful and functional as possible
What happens in the maintenance phase
§ Supportive periodontal care and review of restorations
What are options dependent on
○ Dentist ○ Dental facts ○ Patient ○ Time ○ Medical facts ○ Costs
What do we consider when deciding to treat or extract a tooth
○ How extensive is the caries?
○ Is the tooth restorable?
○ Is the tooth fractured?
○ Will the restoration be successful?
What else do we think about in decision making
• If to be kept, what type of restoration?
• What tooth preparation is necessary?
• What are the other options?
○ More conservative options possible?
Why do we place veneers?
to improve aesthetics
How do veneers improve aesthetics
§ By changing shape, colour, contour
§ Change teeth shape and/or contour
§ Correct peg-shaped laterals
§ Reduce or close proximal spaces and diastemas (interproximal space in centre line)
§ Align labial surfaces of in standing teeth
What is the gruel minimal prep technique
○ Wax up of the veneers are done
○ Stent made on top fo the wax up and we use the stent to do a protemp mockup in the patients mouth
○ Intra-oral mock up
Preparation is into the mock up (can use depth cut burs) to ensure that the only tooth tissue taken away is what is required
When do we not use veneers
○ Poor OH
○ High caries rate
○ Interproximal caries and/or unsound restorations
○ Gingival recession
○ Root exposure
○ High lip line
○ If extensive prep needed (>50% of surface area is no longer in enamel)
○ Consider alternatives (PJC, DBCs, MCCs)
○ Labially positioned, severely rotated and overlapping teeth
○ Extensive TSL/insufficient bonding area
○ Heavy occlusal contacts especially for patients who are class 3
○ Severe discolouration as veneers are opaque so sometimes its better to do a crown or try bleaching before providing the veneers on top
Why do we restore teeth with inlays and onlays
tooth wear cases fractured cusps restoration of root treated teeth replace failed direct resotrations minor bridge retainers
Why do we use inlays and onlays for toothier cases
Increases OVD
Why can we use onlays for root treated teeth
§ Root treated teeth should be provided with a restoration that has cuspal coverage which onlays provide
When do we not use inlays and onlays
○ Active caries and periodontal disease
○ Time
§ Tooth prep and lab fabrication required, may prefer a single visit
○ Cost
Why restore teeth with crowns
○ To protect weakened tooth structure
○ To improve or restore aesthetics
○ For use as a retainer for fixed bridgework
○ When indicated by the design of a RPD
○ To restore tooth function
Why do we use crowns when indicated by RPD
§ Rest seats
§ Clasps
§ Guideplanes
How do crowns restore the tooth function
§ Restore in OVD
When do we not restore with crowns
○ Active caries and periodontal disease
○ More conservation options available as crowns remove a lot of tooth tissue
○ Lack of tooth tissue for preparation
○ Unable to provide post and core
○ Unfavourable occlusion
What are the principles of crown preparation
- preservation of tooth structure
- retention and resistance
- structural durability
- marginal integrity
- preservation of the periodontium
- aesthetic considerations
Describe preservation of tooth structure
Whenever possible preserve sound tooth structure to avoid
§ Weakening the tooth structure unnecessarily
§ Damage to the pulp as 1 in 5 teeth prepped for crowns will become non vital
○ Must balance against criteria for retention and resistance and structural durability
What does under preparation result in
§ Poor aesthetics as the crown is made too thick and bulbous
§ Over built crown
What does overpreparation result in
Over preparation can result in the pulp and tooth strength being compromised
What is retention
prevents removal of the restoration along the path of insertion or the long axis of the tooth prep
What does resistance mean
revents dislodgement of the restoration by forces directed in an apical or oblique direction and prevents any movement of the restoration under occlusal forces
What is ideal taper and how does it help with retention
§ Ideal inclination of opposing walls is 6 degrees
§ It determines the path of insertion
§ Over taper will create multiple paths of insertion so less retentive
How odes length of walls help with retention
§ Longer walls interfere with tipping displacement
§ If its longer then there is a longer way to slide up before it is removed
What are extra means of retention
Grooves and slots
What is path of insertion
his is the imaginary line along which the restoration will be placed onto or removed from the preparation
§ It is set before the preparation is begun and all the features of the preparation must coincide with that line
§ May have to remove some tooth tissue if there is an overhanging cusp
§ Retention is improved by limiting the number of paths of insertion
What is the structural durability
○ Restoration must contain a bulk of material that is adequate to withstand the forces of occlusion
○ It is achieved through occlusal reduction, functional cusp bevel and axial reduction
How is axial reduction done
§ For axial reduction you want to reduce the tooth in two planes labially
What is marginal integrity
○ Finish the configurations § Knife edge § Bevel § Chamfer § Shoulder § Bevelled shoulder
How is preservation of the periodontist done
○ Margins of the restoration should be
§ Smooth and fully exposed to a cleansing action
§ Placed where the dentist can finish them and the patient can clean them
§ Placed at gingival margins whenever possible
□ Placement of the margins subgingival may be required
What are aesthetic considerations
consider which materials provide best aesthetics
What are the functional considerations
§ Has the least destructive preparation
§ Is least destructive to opposing teeth
§ Is best suited to bruxists
What is axial reduction for metal crowns (full veneers and gold crowns)
0,5mm
What is occlusal reduction for metal crowns (full veneers and gold crowns)
- 5mm functional cusps
0. 5mm non functional cusps
What is the finish for metal crowns (full veneers and gold crowns)
0.5mm chamfer
What is axial reduction for traditional porcelains ceramic crowns
1mm
What is occlusal reduction for traditional porcelains ceramic crowns
functional cusps 1.5mm
non functional cusps 1mm
What is finish line for traditional porcelains ceramic crowns
1mm shoulder
What is the axial reduction for metal ceramic crowns
1.3mm
What is the occlusal reduction for metal ceramic crowns
- 8mm functional cusps
1. 3mm non functional cusps
What is the finish line for metal ceramic crowns
- 5mmc hammier where only metal required
1. 3mm shoulder for metal and porcelain (0.4mm metal, 0.9mm porcelain)
What is the axial reduction for all ceramic crowns
1.5mm
What is the occlusal reduction for all ceramic crowns
2mm functional cusps
1.5mm non functional cusps
What is the finish line for all ceramic crowns
1-1.5mm chamfer
Why replace teeth with bridge work
aesthetics occlusal stability function periodontal splinting restore the OVD px preference
How do bridges help with occlusal
Prevent tilting and overeruption of adjacent and opposing teeth
How do bridges help with function
§ Mastication
§ Speech
§ Wind instrument players
How does bridges help with periodontal tx
§ Can brace looser teeth
Can bridges be used to restore the OVD
§ But don’t want to do that just on a bridge, it is usually part of a treatment plan that contains onlays
Why not place a bridge
○ Damage to tooth and pulp ○ Secondary caries ○ Effect on periodontium ○ Cost ○ Failures
What are the designs of a bridge
○ Cantilever (held onto adjacent tooth on one side) ○ Fixed-fixed ○ Adhesive/resin bonded/resin retained ○ 'conventional' ○ Hybrid ○ Fixed-moveable ○ Spring cantilever
What is the communication with patients
verbal and written
What risks should be discussed about tx in communication
○ Invasiveness/reversibility ○ Likely longevity and success rates (evidence based) ○ Possible complications ○ Time involved ○ Costs Alternative options
What should you discuss for informed consent
Why the tx is to be performed
○ Why it is necessary
○ Consequences of not having treatment
○ What risks may be involved (material risks)
○ What alternatives are there (and their risks)
○ Relative costs)
What may patients claim
○ Did not know what treatment was being provided
○ Did not know the cost implications
○ Received no warnings about the risks involved
○ Was not aware of alternative options
Did not give consent
