Diagnosis_and_tt_planning IN FIXED PARTIAL

TREATMENT PLAN

1. Diagnosis and tt planning in
FDP-II
Dr Jitendra Rao
Dept of Prosthodontics

2. Indication for FDP/FPD
•Mutilated crown or tooth
•Missing tooth
•Endodontically tt teeth
•Discolored teeth
•Fractured tooth
•Spacing

3. Contraindication
•High caries index
•High DMF index
•Unfavorable abutments
•Age below 18yr of age
•Medically compromised patients
•Neurological patients
•Xerostomic patients
•Patients with radiotherapy and chemotherapy

4. Articulators:Articulatorsvarywidelyintheaccuracywithwhich
theyreproducethemovementsofthemandible.
Non-adjustablearticulator:device/instrumentthatiscapableof
onlyahingeopening
Semi-adjustablearticulator:
•Allowsacloseapproximationofanatomicdistancebetweenthe
axisofrotationandtheteeth
•castsaremountedusingfacebowpproximatetransverse
horizontalaxis,theradiusofmovementproducedonthe
articulatorwillreproducethearcofclosurewithrelativeaccuracy
andanyresultingerrorwillbeslight
•Intercondylardistancesareadjustabletosmall,mediumand
largeconfigurations

5. •This type of articulator can be used for the fabrication of most
single units and fixed partial denture
•Use face bow-arbitrary
•Arcon articulators e.g. Whip mix–used more for fixed
restoration
•Non arcon e.g Hanau series-used for complete denture
Fully adjustable articulator:
•designed to reproduce the entire character of border
movements, including immediate and progressive lateral
translation, and the curvature and direction on condylar
inclination
•Inter condylar distance is completely adjustable
•Face bow -kinematic

7. Locating the transverse hinge axis
•axis of rotation that is as close as possible to the transverse
horizontal axis of the patient’s mandible
•The most accurate way to determine the hinge axis is by
the “trial and error” method developed by McCollum and
Stuart in 1921 (using a kinematic face bow).
•Arbitrary face bows can also use but they must have an
acceptable accuracy.
•Caliper style ear piece face bows possess a relatively high
degree of accuracy with 75% of the axes located by it falling
within 6 mm of the true hinge axis

9. Single tooth restoration
•INTRA CORONAL RESTORATIONS -depended on the strength
of the remaining tooth structure for structural integrity e.g
inlay,onlay
•EXTRA CORONAL RESTORATIONS
If insufficient tooth structure exists to retain the restoration
within the crown of the tooth, an extracoronal restoration, or
crown is needed.
–Partial veneer crown
–Full metal crown

10. TREATMENT PLANNING FOR REPLACEMENT OF
MISSING TEETH
Important ones are
Biomechanical factors
Periodontal factors
Esthetics
Financial factors
Patient’s wishes

11. Abutment Evaluation
Abutment is a tooth, portion of tooth or portion of a
dental implant that supports or retain a prosthesis
Abutment teeth are called upon to withstand the forces
normally directed to the missing teeth, in addition to those
usually applied to the abutments
•Whenever possible an abutment should be a vital tooth.
However, a tooth that has been endodontically treated which
is asymptomatic with radiographic evidence of a good seal
and complete obturation of the canal can be used as an
abutment. If the endodontically treated tooth does not have
sound tooth

12. •The roots and their supporting tissues should
be evaluated for 3 factors:
•Crown-root ratio
•Root configuration
•Periodontal ligament area

13. Ideal crown-root ratio for a tooth to be
utilized as a fixed partial denture abutment

14. StudiesbyKlaffenbachin1936haveshownthatocclusalforcesexerted
againstprostheticapplianceshavebeenshowntobeconsiderablyless
thanthatagainstnaturalteeth(about160lb)
FPD against RPD 26.0lb
FPD against FPD 54.4 lb
FPD against natural teeth 150.0lb

15. Root configuration-

16. Periodontal ligament area-
Johnston et al in 1971 in their statement
designated as “Ante’s law” said that the root
surface area of the abutment teeth had to equal
or surpass that of the teeth being replaced with
pontics

17. RootSurfaceArea(mm)
Teeth Maxillary Mandibular
CentralIncisor 204 154
Lateral 179 168
Canine 273 268
FirstPM 234 180
SecondPM 220 207
FirstMolar 433 431
SecondMolar 431 426
Jepsenin1963hasreportedareasoftherootsurfacesofthevarious
teethwhichisalsotermedasJepsen’srule

18. Biomechanical Considerations
•All fixed partial dentures, long or short spanned bend and flex under
masticatory load
•Bending or deflection varies directly with the cube of the length and
inversely with the cube of occlusogingival thickness of the pontic
•( D α L
3
) where D is defelection, L is length of the pontic span on
given occlusogingival height
•Compared with a fixed partial denture having a single tooth pontic
span, a two tooth pontic span will bend 8 times as much
•Double abutments are sometimes used as a means of overcoming
problems created by unfavourable crown-root ratios and long span.
There are several criteria that must be met, if a secondary abutment
is to strengthen the fixed partial denture

19. SPECIAL PROBLEMS
Pier abutments:
An edentulous space can occur on both sides of a tooth,
creating a lone, free standing pier abutment
Physiologic tooth movement, arch position of the
abutments and a disparity in the retentive capacity of the
retainers can make a rigid 5-unit fixed partial denture as a
less than ideal plan of treatment
Forces are transmitted to the terminal retainers as a result
of the middle abutment acting as a fulcrum, causing failure
of the weaker retainer

20. Pier abutment

21. •The use of a non-rigid connector has been recommended to
reduce this hazard
•The most commonly used non-rigid design is a T shaped key
that is attached to the pontic and a dove tail key way placed
within a retainer
•The key way of the connector should be placed within the
normal distal contours of the pier abutment and the key
should be placed on the mesial side of the distal pontic
•Non rigid connector transfer shear stress to bone rather than
connector as well as minimize mesiodistal torqueing of
abutment

22. Tilted Molar Abutments
•Whentheteetharemesiallytiltedbeyondanoptimaldegreeof
tiltdeleteriousforcesactovertheabutmentcausingverticalbone
lossaroundthemesialportionofteeththusfurther
compromisingperiodontalsupportandweakeningofthe
abutment
•Iftheseteethareusedasabutmentforfixedpartialdenturesit
willleadtofailureofprosthesis
•The over-all objective in molar uprighting is ideal positioning of
the molar which will eventually become an abutment tooth for a
fixed prosthesis. The ideal position will provide an optimal
periodontal environment for the molar

24. A proximal half crown can be used as a retainer on the distal
abutment. This preparation design is a 3 ¼ crown that has been
rotated 90°. It can be used only if the distal surface is untouched
by caries
A telescoping crown and coping can also be used as a retainer for
the tilted molar. A full crown preparation with heavy reduction is
made to follow the long axis of the tilted molar. An inner coping is
made to fit the tooth preparation. The proximal half crown that
will serve as the retainer for the FPD is fitted over the coping
A non-rigid connector is another solution to the problem. A full
crown preparation is done on the tilted molar, with its path of
insertion parallel with the long axis. A box form is placed on the
distal surface of the premolar to accommodate a keyway in the
distal of the premolar crown

25. Cantilever FPDs
•A cantilever FPD is one that has an abutment or abutments at
one end only, with the other end of the pontic remaining
unattached. This is a potentially destructive design with the
lever arm created by the pontic
•Abutment teeth for cantilever FPDs should be evaluated for
lengthy roots with a favorable configuration, good crown root
ratios and long clinical crowns.

27. Canine Replacement FPD/ Canine Rule
•This is a problem because often the canine lies outside the
interabutment axis
•The abutments are the lateral incisor, usually the weakest in
the entire arch and the first premolar, the weakest posterior
tooth
•A FPD replacing maxillary canine is subjected to more stress
than that replacing a mandibular canine, since forces are
transmitted outward on the maxillary arch. So the support
from secondary abutments will have to be considered.

28. Books
•Rosensteil
•Shillingburg