prosthodontics fixed partial denture abutment evaluation

1. DIAGNOSIS AND
TREATMENT
PLANNING IN FPD
AND ABUTMENT
EVALUATION
Anishma Krishnan

2. CONTENT
Introduction Diagnosis
Treatment
planning
Abutment
evaluation
Biomechanical
and special
considerations

3. Introduction
Fixed partial denture ; any dental prosthesis
that is luted , screwed or mechanically attached
or otherwise securely retained to natural teeth
tooth roots and or supported for the dental
prosthesis and restoring teeth in a partially
edentulous arch it cannot be removed by the
patient.
[GPT;9]
3

4. DIAGNOSIS
Presentation Title
A thorough diagnosis of both hard and soft tissues
this must be correlated with the individuals overall physical health and
psychological needs
In a case history the personal information of the patient should be
recorded which includes
name
age
sex
address
contact number
family history
socio –economic status

5. STEPS IN DIAGNOSIS
CHIEF
COMPLAINT
Patients primary
reason for seeking
treatment must be
recorded regarding
• Comfort
• function
• appearance
MEDICAL HISTORY
• Medication
• Allergies
• CVS disorders
• Epilepsy
• Diabetes
• Thyroid
• Anemia
• Xerostomia
TMJ &
OCCLUSAL
EVALUATION
• Clicking
• Popping
• Crepitus
• deflection
• deviation
• mouth opening
INTRAORAL
EXAMINATION
• Periodontal
status
• pathology
• Edentulous
ridge
evaluation;
• oral hygiene
status
• Bruxism
• wasting
disease
DIAGNOSTIC
CAST
• mounted on
semi
adjustable
articulator.
• provide a
greater deal of
information for
diagnosing
problems and
arriving at a
treatment plan
5

6. FULL MOUTH
RAGIOGRAPH
• Caries
• periapical lesion
• alveolar bone level
• crown root ratio
• retained root tips
• PDL space widening
• pathology of born[ cyst
/tumor]
• thickness of cortical
bone plates around
teeth
TREATMENT PLANNING
TREATMENT PLAN ; the
sequence of procedures
planned for treatment of a
patient after diagnosis
[GPT 9]
 TREATMENT PLANNING
FOR SINGLE TOOTH
RESTORATION
 TREATMENT PLANNING
FOR REPLACEMENT OF
MISSING TEETH

7. TREATMENT PLANNING FOR SINGLE TOOTH
RESTORATION
Using cast metal , ceramic and metal ceramic restorations large area of missing coronal
tooth structure can be restored
Destruction
of tooth
structure
cast metal or
ceramic >
amalgam or
composite resin
ESTHETICS
Partial veneer
restoration
all ceramic crowns
margin equi-gingival
or sub -gingival
cemented restoration
demands ;a good
plaque control
Or will cause
restoration crown
failure
RETENTION
Full coverage
crowns are the
most retentive
FINANCIAL
CONSIDERATIO
NS
7
PLAQUE
CONTROL
Metal ceramic
restoration
veneers

8. INTRA CORONAL RESTORATION
GIC
RESTORATION
COMPOSITE
RESIN
SIMPLE
AMALGAM
RESTORATION
COMPLEX
AMALGAM
RESTORATION
8
When sufficient coronal tooth structure exist to retain and protect a restoration
under the anticipated stresses of mastication , an intra-coronal restoration can be
employed

9. EXTRA CORONAL RESTORATION
Insufficient coronal tooth structure
Defective axial tooth structure
PARTIAL
VENEER
CROWN
To restore a tooth with
one or more intact axial
services with half or
more of the coronal
tooth structure
remaining
FULL METAL
Restore teeth with
multiple defective axial
surfaces
aesthetic expectations
ALL CERAMIC
CROWNS
Full coverage
indicated in high
aesthetic area such
as incisors
CERAMIC
VENEERS
produce good cosmetic
result
moderate incisal
chipping or
proximal lesions

10. Removable
partial
denture
Conventional
tooth
supported
FPD
Resin bonded
tooth
supported
FPD
Implant
supported
FPD
Patient's
needs
TREATMENT PLANNING FOR REPLACEMENT OF
MISSING TEETH
Presentation Title

11. Presentation Title

12. ABUTMENT EVALUATION
Abutment; A tooth, a portion of tooth, or that portion of a dental implant that
serve to support and/or retain a prosthesis [GPT 9]
That part of structure that directly receives thrust or pressure or an
anchorage
A FPD mainly transmit force through abutment to the periodontium

13. CROWN LENGTH
ROOT
PROXIMITY
Adequate clearance
between roots of
proposed abutment
CROWN FORM
PEG LATERALS
CROWN ROOT
RATIO
OPTIMUM RATIO 2: 3
1:1 MAXIMUM RATIO
ACCEPTABLE
DEGREE OF
MUTILATION
size ,number, location of
carious lesion
PERIODONTAL
LIGAMENT
HEALTH
MOBILITY
ROOT LENGTH
AND FORM
Directly proportional to
stability and strength of
prosthesis
ENDODONTIC
STATUS

14. CROWN LENGHT
Presentation Title
• Abutment teeth must have adequate occlusive cervical Crown length to
achieve sufficient retention
• Management: gingivectomy can be done with short clinical Crowns to
ensure adequate retention.
• Sub gingival margins can be given in such prosthesis.

15. CROWN FORM
Presentation Title
Can interferes with the preparation parallelism
Examples: Peg lateral
Anterior teeth with poorly developed cingula /Short proximal walls
Mandibular premolar with poorly developed lingual cusps, short Wall Thin
incisors
Management: Full coverage crowns to improve support and retention

16. ROOT LENGTH AND FORM
Presentation Title
Should possess adequate root Anchorage in the bone to effectively resist an
transmit occlusal load
Directly proportional to stability and strength of prosthesis
Roots with parallel sides and developmental grooves > conical
• Single rooted tooth with irregular
configuration , curvature in apical third >
perfect taper.
• Well aligned tooth > tilted one
• Root broad labiolingual > round in cross
section
• Multi rooted >single rooted tooth

17. ROOT PROXIMITY
Presentation Title
There must be adequate clearance between roots of proposed abutment to
permit development of physiologic embrasures in the completed prosthesis
Example: Malposition anterior teeth
Malpositioned mesiobuccal root of maxillary molar
Evaluation: radiographic examination
Management: Selective extraction or root resection procedures can be done

18. CROWN ROOT RATIO
Presentation Title
‘Ratio is the measure of the length of tooth occlusal to the alveolar crest
of bone to length of root embedded in the bone’’
linear measurement of tooth above the bone and within the bone
The ratio is high it is less likely that tooth will be able to withstand occlusal
forces
 The ratio of 1 :1 is acceptable in following condition
Opposing occlusion is a removable prosthesis
Opposing teeth is periodontally weak -mobile tooth
Forces exerted on abutment teeth is less

19. Presentation Title
OPTIMUM CROWN TO ROOT RATIO 2: 3
1:1 MAXIMUM RATIO ACCEPTABLE UNDER CERTAIN CIRCUMSTANCES

20. PERIDONTAL LIGAMANT HEALTH
Presentation Title
Healthy periodontal tissues
prevent encroachment of biological width 2mm coronal to alveolar crest
Evaluation
1. inflammation
2. Gingival architecture and stippling should be noted
3. Pockets
4. Band attached gingiva.
5. Plaque
6. Bone loss

21. ANTE’S LAW
The combined Pericemental area of the abutment teeth should be equal to or
greater than the pericemental area of the tooth or teeth to be replaced
Presentation Title 21

22. 22
calculation average value of
root surface area of
permanent teeth are given
by Jepson

23. TILT/LONG AXIS OF TOOTH
Presentation Title
Could happen to any tooth adjacent to
edentulous space if not replaced for a longer
period of time
The most common ; Mand 2nd molar tilting
mesially
MANAGEMENT
proximal stripping
orthodontic treatment
proximal one half crown
telescopic crown
non rigid connectors

24. ENDODONTIC STATUS
Abutment teeth with poor pulpal health need endodontic treatment prior to
tooth Preparation
Endodontically treated teeth can successfully function as abutment
Radiographs and vitality test
Full coverage retainers ; minimize the possibility of fracture
Direct pulp capping with amalgam or composite resin offers risk factor

25. Presentation Title
A post and core ;depending on the amount of tooth destruction
contraindicated ; cantilever FPD
Endodontic treatment may be necessary for a supraerupted or
misaligned teeth to improve the arch relationship

26. MOBILITY
Presentation Title
Tooth with greater than normal mobility can be used as abutments
depending upon degree of mobility
GRADE 1- can be used for prosthesis after required management
GRADE 2-consideration of other factors
GRADE 3- NOT IDEAL
If cause is deflective occlusal contact : occlusal correction +short span
prosthesis
If cause is periodontal problem : splinting ;cannot be used for long span
prosthesis

27. Presentation Title

28. OVERLOADING OF ABUTMENT
Presentation Title
Different masticatory forces ; on different prosthesis
Bruxism and clenching
Average values for force exerted against the fixed prosthesis is different.
This will directly effect the selection of the number of abutments.

29. CARIES
Presentation Title
If it is deep vitality testing must be done.
Wasting disease,
hypoplasia
removal of existing filling and checking for the extent of the damage previously
caused by lesion.
IOPAR
 Management:
• Dietary advice
• oral hygiene measures
• Fluoride treatment,
• Regular follow up appointments.
• RCT

30. BIOMECHANICAL
CONSIDERATION
1. SPAN LENGTH
2. ARCH FORM
3. DISLOADGING FORCE
4. DOUBLE ABUTMENT
5. ARC OF ROTATION
Presentation Title

31. The length of the arch increases
The number of teeth be replaced increases
increased load on abutment
FPD also flexes more
SPAN LENGHT

32. Presentation Title
To reduce flexure long span FPD
1. Pontic with increased thickness
2. Double abutment to distribute forces
3. Nickel chromium alloy high rigidity
 Pontic thickness is halved, then flexure will be 8 times

33. The curvature of the arches often places pontic
facially to the straight line that is a fulcrum line
drawn between the teeth immediately adjacent to
the edentulous span
This relationship creates a Lever arm that can exert
excessive torquing forces on the abutment teeth.
ARCH FORM
The length of this Lever arm will be more in
tapered are than in the square arch.
It is commonly seen when all four anterior
teeth have been replaced.
Double abutment must be used to provide
additional retention so as to offset Lever
arm length.

34. All fixed partial dentures flex due to forces
applied to the pontics.
This flexure causes the retainers to dislodge
from the abutments.
This dislodging forces on fixed partial denture
act in mesiodistal direction.
Retentive grooves to counter these forces are
placed buccally and lingually on the FPD
DISLOADGING
FORCES

35. DOUBLE ABUTMENT
Presentation Title
This report to the use of two adjacent teeth
at one or both ends of the FPD as
abutments
The abutment adjacent to the edentulous
area is called the primary abutment and the
abutment adjacent to this is called
secondary abutment

36. INDICATION
1. Long span FPD
2. Unfavorable Crown to root ratio
3. To increase retention of restoration
4. Increase area of supporting periodontal
ligament and bone
5. Splint and stabilize periodontally compromised
teeth
CRITERIA FOR SECONDARY
ABUTMENT
• Must have root surface area and favorable Crown to root ratio
• Similar retention as primary abutment
• Sufficient crown length
• Space should be present between adjacent abutments. This
is to prevent the impingement of gingiva under the connector

37. Arc of rotation
LENGTH
• Occlusogigival length is am important factor in both retention
and resistance
• The longer the preparation – more surface area- more
retention
• The preparation on the smaller tooth will have a short rotation
radius for the arc of displacement, and the incisal portion if the
axial wall will resist the displacement.
• The longer rotational radius on the larger larger preparation
allows for a more gradual arc of displacement and the axial
wall dosenot resis t removal.

38. Presentation Title
the arc of displacement refers to the path along which tooth
material is removed during preparation. It is essentially the
trajectory that the dentist follows to create space for the restoration.
The arc of displacement considers the movement of the tooth
structure during the preparation process, aiming to minimize stress
on the remaining tooth and ensure optimal support for the
restoration.
the radius of rotation defines the central axis around which the
tooth rotates during preparation, while the arc of displacement
outlines the path of tooth reduction to accommodate the
restoration.

39. Presentation Title

40. SPECIAL
CONSIDERATIONS
1. PIER ABUTMENT
2. TILITED MOLAR
ABUTMENTS
3. CANINE REPLACEMENT
FPD
4. CANTILEVER FPD
Presentation Title

41. PIER ABUTMENT
It is a special consideration during FPD
AKA intermediate abutment
DEFINITION
A NATURAL TOOTH LOCATED BETWEEN
TERMINAL ABUTMENTS THAT SERVE
TO SUPPORT A FIXED OR A
REMOVABLE PROSTHESIS
GPT-8
Presentation Title
An edentulous space can occur on both sides of a tooth
,create a lone, freestanding pier abutment
A completely rigid connector is not indicated in these
cases

42. Usually in this case a 5unit FDP is made
But -If made using RIGID CONNECTORS
using all the natural teeth adjacent to
edentulous area as abutment with pier in
centre
It will be a failure because of
Physiologic tooth movement,
arch position of the abutments,
disparity in the retentive capacity of the
retainers

43. To overcome this issues while using a
rigid connector
The non rigid connectors is a broken-stress mechanical union of pontic and
retainer
Commonly used design ; “T” shaped key on pontic
dovetail keyway within retainer
Use of the non rigid connector is restricted to short span FPD replacing one
tooth

44. Presentation Title

45. TILT/LONG AXIS OF TOOTH
Could happen to any tooth adjacent
to edentulous space if not replaced
for a longer period of time
Common ; mand 2nd molar
Further complication is third molar present
Since the path of insertion is determined by the smaller premolar abutment
surface of the tipped third molar will encroach on the path of insertion there for
preventing the placement of the prosthesis

46. management
Proximal
stripping
Orthoontic
management
Proximal one half
crown
Non rigid
connectors
Presentation Title

47. CANINE REPLACEMENT FPD
Presentation Title
FPD replacing canine can be difficult because the canine often lies outside
the inter abutment axis
Abutments ;lateral incisors [weakest tooth in anteriors]
;1st premolar[weakest tooth in posteriors]
FPD replacing max canine is subjected to more stresses than that replacing
mand canine ;
because courses are transmitted outward [labially]on the maxillary arch
against the inside of the curve[its weakest point]

48. Presentation Title
No FPD replacing a canine should replace more than one additional tooth
An edentulous space created by the loss of canine and any two contiguous
teeth is best restored with RPD

49. CANTILEVER FPD
Presentation Title
A cantilever this one that has an abutment or abutment at one end only, with
the other end of the pontic remaining unattached
Lever arm created by pontic ; depressed under forces with a strong occlusal
vector
Cantilever can be used for replacing a maxillary lateral incisor [abutment
canine]
Mesial rest on central incisor

50. Presentation Title

51. Presentation Title

52. conclusion
Presentation Title
The scope of fixed prosthodontic treatment can range from restoration of
a single tooth to the rehabilitation of the entire occlusion .Component
treatment depends on the careful examination of all available information
a definitive diagnosis and careful treatment planning that gives good
prognosis The proper abutment evaluation and selection is also an
integral part of equity trading fabrication any failure in these steps can
cause failure of entire prosthesis

53. REFERENCE
Presentation Title
• FUNDAMENTALS OF FIXED PROSTHODONTICS -Herbert .T .
Shillingburg [4th edition ]
• CONTEMPORARY FIXED PROSTHODONTICS –Rosenstiel [1st south
Asia edition ]
• TEXTBOOK OF PROSTHODONTICS –V . Rangarajan [4th edition ]