Diagnosis and Treatment Planning in Fixed Prosthetics

1
Diagnosis and Treatment Planning in Fixed
Prosthetics

• Class of 2008
• January 26, 2006
• Guggenheim, 8 am

2
Quote of the Day

• A coach is someone who tells you what you dont
  want to hear, who has you see what you dont want
  to see, so you can be who you have always known
  you could be.
• Tom Landry,
• Former Dallas Cowboys coach

3
Fixed Prosthetics

• What is it?
• Is the field of restorative dentistry where
  restorations are cemented into place (not readily
  removable). These can include a single tooth or
  an entire arch. This course will concentrate on
  porcelain fused to metal single crowns and fixed
  partial dentures (aka FPDs or bridges) of
  differing materials.

4
Examples of Fixed Prosthetics
5
Fixed Prosthetics Nomenclature

• Abutment
• Abutment Preparation
• Retainer
• Connector
• Pontic
• Edentulous Ridge/Space

6
Fixed Prosthetics

• What are the functions of a fixed partial
  denture?
• Provide Proper Occlusal Function
• Maintain Arch Integrity/Tooth Position
• Maintain Occlusal Relationships
• Protect Preserve the Remaining Structures

7
Diagnosis Treatment Planning

• Why bother?
• The process of diagnosis and treatment planning
  helps us attain a comprehensive and complete
  guide to care for any given patient and their
  particular situation. It allows for the care
  rendered to be logical both in plan and action.

8
Diagnosis Treatment Planning

• Before a Diagnosis (Dx) is made, thorough data
  collection is necessary.
• Radiographs
• Articulated Diagnostic Casts
• Medical, Social, and Dental Histories
• Clinical Examination
• Periodontal Charting
• Endodontic Vitality Tests
• Patient Expectations of Treatment

9
Diagnosis Treatment Planning

• Treatment (Tx) Planning is the integration of
  data collection and diagnosis to form an
  omniscient ordered guide of treatment.
• It can be a very complex and confusing process if
  the patients needs are great. So, having a
  well-thought-out plan prior to beginning any
  treatment is a key to success.

10
Dx Tx Planning for Fixed Prosthetics

• Nature of Opposing Occlusion
• Desired Final Contour of Restoration or
  Intra-arch Harmony
• Material Bulk Usage Requirements
• Path of Insertion

• Existing Tooth Conditions
• Extent of Defective Structure/Disease
• Bridge Span Length
• Periodontal Health
• Endodontic Considerations

11
Order of Treatment Plans

• Restorative Phase
• Operative Dentistry
• Fixed Prosthetics
• Removable Prosthetics
• Maintenance Prophylaxis Phase
• Periodontal
• Restorative
• Radiographic

• Disease Control Phase
• - patients are freed of pain rampant disease
• Endodontics
• Oral Surgery
• Caries Control
• Periodontal Phase
• Scaling/Root Planing Surgical Methods
• Improved Patient Homecare
• Re-Evaluation

12
FPD Treatment Planning

• Abutment Evaluation
• Tooth Vitality
• Periodontal Status
• Crown-to-Root Ratio
• Root Configuration
• Periodontal Surface Area (Antes Law)
• Clinical Crown Length
• Relation of Long Axis to Path of Insertion

• Biomechanical Considerations
• Management of Destructive Forces
• Length of Span (Law of Beams)
• Pier Abutments
• Cantilevered Bridges

13
Abutment Evaluation

• Tooth Vitality
• Ideally, wed like for an abutment to be free of
  any endodontic complications.
• However, the use of endodontically treated teeth
  is not contraindicated as long as it has enough
  structure or build-up material to adequate serve
  as an abutment.
• Teeth with questionable vitality require a choice
  of doing elective endodontics prior to treatment
  or seeing what time has to offer

14
Abutment Evaluation

• Periodontal Status
• Inflamed gingiva bleed and make preparation and
  impression making more difficult.
• Mobile teeth may not be able to support any span
  under occlusal stress for very long.
• We prefer to do any restorative work on stable
  teeth and around healthy gingiva.

15
Abutment Evaluation

• Crown-to-Root Ratio
• Ideally, a clinical crown-to-root ratio of 23 is
  sought after. Minimally, wed like to see a 11
  for a tooth to be considered for use as an
  abutment.

16
Abutment Evaluation

• Root Configuration
• The shape of the roots also determines the
  ability of the root to handle occlusal forces.

Teeth with a wider bucco-lingual dimension than
mesio-distal have a greater ability to handle
load than conically shaped roots.
Multi-rooted teeth with separated roots are
better at displacing occlusal load than teeth
with conjoined roots.
17
Abutment Evaluation

• Periodontal Surface Area (Antes Law)
• Ideally, the periodontal surface area of the
  abutment teeth should be greater than or equal to
  the periodontal surface area of the missing
  teeth.
• In cases where the periodontal surface area seems
  inadequate, the use of multiple teeth for
  abutments may be indicated depending on other
  biomechanical factors.

18
Abutment Evaluation

• Periodontal Surface Area (Antes Law)

• Order of Abutments concerning Periodontal Surface
  Area
• First Molar
• Second Molar
• Canine
• First Premolar
• Second Premolar
• Central Incisor
• Lateral Incisor

Maxillary Arch
19
Abutment Evaluation

• Periodontal Surface Area (Antes Law)

• Order of Abutments concerning Periodontal Surface
  Area
• First Molar
• Second Molar
• Canine
• Second Premolar
• First Premolar
• Lateral Incisor
• Central Incisor

Mandibular Arch
20
Abutment Evaluation

• Clinical Crown Length
• Abutment teeth (and preparations) should have
  adequate outermost mesial and distal wall heights
  in order to counteract the dislodging
  mesial-distal forces that a bridge will
  encounter.
• Conversely, single unit crowns have a tendency to
  dislodge in a facial to lingual/palatal
  direction.
• Teeth with short clinical crowns may not be ideal
  abutments. The use of crown lengthening surgery,
  opening vertical dimension, or multiple abutments
  might be considered.

21
Abutment Evaluation

• Relation of Long Axis to Path of Insertion
• Ideally, every abutment tooths long axis would
  coincide with the desired path of insertion of
  the restoration.
• Usually, the path of insertion of a fixed bridge
  is determined by the path of insertion of the
  smallest abutment tooth.
• Teeth with disconcordant paths of insertion may
  require orthodontic uprighting, minor
  recontouring, a coping, interlocking features, or
  special preparations.

22
Biomechanical Considerations

• Management of Destructive Forces
• The design of the bridge should allow for
  occlusal forces and dislodging forces, like
  torque, flexure, and tension to be handled.
• Occlusion should be designed to optimize the
  distribution of occlusal forces evenly throughout
  the envelope of motion over the entire mouth.

23
Biomechanical Considerations

• Length of Span
• (Law of Beams)
• The Law of Beams is an engineering principle that
  states that as the length of the span increases,
  the flexure of a system will be the increase in
  length to the power of three (cubed).
• Therefore, doubling the length would yield 8
  times the flexure. Tripling the length would
  yield 27 times the flexure.

24
Biomechanical Considerations

• Height of Connector (Law of Beams)
• As the height of the span decreases, the flexure
  of a system will be the increase in length to the
  power of three (cubed).
• Therefore, halving the connector height would
  yield 8 times the flexure. A connector only 1/3
  as tall would yield 27 times the flexure.

25
Biomechanical Considerations

• Law of Beams Summary
• The length of span and height of connectors are
  important considerations along with the amount
  and direction of the occlusal forces it will
  encounter when designing a bridge. This law
  refers to the amount of flexure that the
  restoration will undergo.

26
Biomechanical Considerations

• Pier Abutments
• Are abutment teeth where an edentulous space lies
  on each side. Because they lie in the middle of
  the span, they can act as a fulcrum for
  destructive forces.

27
Pier Abutments

• The potential stress from pier abutments needs to
  be dissipated. When the edentulous space is only
  one tooth long, one can incorporate a non-rigid
  connector on the distal portion of the pier
  abutment to act as a stress relief point.

28
Non-Rigid Connectors

• Non-rigid connectors placed on the distal aspect
  of both canines to dissipate force.

29
Biomechanical Considerations

• Cantilevered Bridges
• Occasionally, a bridge may not have abutment
  teeth on each end of the bridge. In the case
  where the pontic is the end of the bridge, we can
  these cantilevered bridges (e.g. diving board)
• These can only be used in certainly situations
  where the stress can be distributed nicely and
  not put undo stress on the abutment teeth.
  Occlusion is always minimized and/or ignored on
  the pontic.

30
Biomechanical Considerations

• Commonly employed cantilevered bridges are
  abutted to canines and spanning across the
  lateral incisor area.
• The force on the cantilevered unit puts the
  furthest abutment under tension and torque.

31
Special Thanks to

• Dr. Sajid Jivraj for his donated materials in
  this lecture , Dr. Herbert Shillingburg for his
  oustanding textbook on Fixed Prosthodontics, and
  Dr. Paolo Corrado, Dr. Nikitas Mordohai, and Dr.
  Richard Lin for their pictorial contributions to
  this presentation.