Treatment Planning & Biomechanics Flashcards by sophie rosen

What is a Fixed Partial Denture (Bridge)?

-A dental prosthesis definitively attached to remaining teeth or to dental
implants, which replaces one or more missing teeth.

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Abutment –

Natural tooth or implant serving as attachment for Fixed Partial Denture

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Retainer –

Extra-coronal restoration cemented to abutment

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Pontic –

Artificial tooth suspended from abutments

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Connector –

Rigid (or non-rigid) connecting pontic and retainers

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Edentulous Ridge –

The site of the alveolar bone and its covering soft tissues that remains after tooth
loss.

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Consequences of Unrestored tooth loss.
Tooth Movement
(4)

-Over-eruption
-Tilting and drifting
-Disruption of occlusion
-Pain, TMJ disfunction

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Consequences of Unrestored tooth loss.
No tooth Movement
(1)

for some reason, some teeth never move
after loss of proximal or opposing contact.

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— are produced when a FPD is made to the
over-erupted dentition.

Occlusal interferences

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Opposing tooth being restored to a corrected occlusal plane
prevents interferences. This however, may require treatment.

Odontoplasty, restoration, crown, RCT, crown lengthening, intrusion,
or even extraction.

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When teeth have been missing
for a long time, extreme closure
of the inter-occlusal distance
can occur which requires

more
extreme treatment planning
and for the general dentist,
likely a referral to a
prosthodontist for treatment of
this complexity.

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Partially Edentulous Patient
– Selection of the type of Prosthesis. Options:
(4)

-Removeable Partial denture
-Tooth supported Fixed Partial Denture
-Implant supported Fixed Partial Denture
-Always the option to do nothing.

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-Tooth supported Fixed Partial Denture
(3)

-Conventional
-Resin-Bonded
-Cantilever

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Indications for Removable Partial Denture:
(6)

-Long edentulous spans
-No distal abutment
-Multiple Edentulous spaces
-Abnormal abutments – Tipped, divergent or
few abutments
-Periodontally weakened primary abutments
(Bridge abutments compromised)
-Severe loss of tissue/bone in residual ridge

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Could a bridge be placed from 11-14 – YES!
What information would you need to know to
determine the prognosis of a fixed bridge for
treatment planning?

X-rays
Perio charting
Decay prevention
Home care
Reason for previous tooth loss
Clencher/grinder?
Finances?
Condition of existing crowns #11 and #14
What else?

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Fixed Partial Denture

A dental prosthesis definitively attached to remaining
teeth or dental implants, which replaced one or more
missing teeth.

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Indications for a Fixed Partial Denture
(3)

-To replace function of missing teeth
-To stabilize occlusion and keep teeth from drifting and extruding
-To create esthetics and phonetics

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Need Properly distributed abutments
(3)

Abutment on both ends of the edentulous space
Span length falls within structural limits
Straight alignment of restoration (slight variations)

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Abutment strength
(4)

Abutments need to be restorable
Peridontally sound and stable
No questionable pathology (PARL, non-vital)
Occlusal harmony

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Contraindications for Fixed Partial Denture
(3)

Excessive loss of alveolar ridge
Abutments not restorable
Abutments are periodontally compromised

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Excessive loss of alveolar ridge
(3)

Difficultly cleaning
Difficult to make esthetic
**Possibly able to correct to some degree with bone graft/augmentation with
periodontal surgery

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Abutments not restorable
(2)

Short clinical crown
Heavily restored already

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Abutments are periodontally compromised
(4)

Loss of bone
Crown to root ratio
Span between abutments too long
***Virgin or minimally restored abutments? Prefer to pursue implant options to preserve
these potential abutment teeth.

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What does an ideal Fixed Partial Denture look like?
(3)

-Periodontally sound abutments
-Tissue follows contour of pontic and connector
-Span is within structural parameters

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What are the criteria we use for Abutment evaluation? Restorative assessment – (2)

Coronal tooth structure Previous restorative treatment

What are the criteria we use for Abutment evaluation? Endodontic assessment – (2)

What is the pulp status PARL? Previous endo in-tact?

What are the criteria we use for Abutment evaluation? Periodontal assessment – (2)

Crown to root ratio, Root configurations, Periodontal surface area

What are the criteria we use for Abutment evaluation? Abutment positional assessment – (1)

Is the tooth tilted, inclined, etc? What is the tooth orthodontic position? Path of Insertion achievable?

What are the criteria we use for Abutment evaluation? Radiographic assessment –

anomalies present?

What are the criteria we use for Abutment evaluation? (3)

Clinical exam Radiographic exam Diagnostic casts (articulated on full- size articulator w/ facebow)

Abutment Evaluation – Coronal Tooth Structure Remove all caries, old restorations, then evaluate: -endo: (3) -Proximity of cavity depth to -BWX – -Adequacy of

Pulp Exposure, symptomatic tooth, Periapical pathology? alveolar crest Biologic width violation likely? retention/resistance form

Abutment Evaluation – Pulpal Health -Vital tooth?

– tooth asymptomatic with sound tooth structure remaining

Abutment Evaluation – Pulpal Health Non-vital tooth?

– RCT if sound tooth structure remaining. Post may be needed.

Abutment Evaluation – Pulpal Health Existing RCT?

– Assess first. PARL? Healthy RCT? Over fill? Previous post adequate?

skipped Abutment Evaluation – Pulpal Health Questionable?

– deep excavation, near pulp exposure, pinpoint exposure, inadequate RCT or post? Address previous RCT and retreat, replace post

Current PA radiographs (less than --- months old) to confirm health of abutments.

Periodontal health is a prerequisite for any fixed prosthodontic restorations (3)

-Need a zone of attached tissue - No mobility -Patient home care adequate

Additionally – (3) all need to be assessed and evaluated.

Crown to root ratio, Root shape and configuration, Periodontal ligament area

The ratio of the portion of the tooth occlusal to the alveolar crest (crown) versus the portion of the tooth embedded in bone (root). Optimum C:R is Minimum C:R is --- for fixed restorations

2:3 1:1

Horizontal bone loss dramatically reduces

supported root surface area

The --- root shape diminishes the actual area of support more than expected from the height of the bone

conical

The center of rotation (R) moves --- and the lever arm (L) ---, greatly magnifying the forces on the supporting structures.

apically increases

The center of rotation (R) moves apically and the lever arm (L) increases, greatly magnifying the forces on the supporting structures. This can

increase tooth mobility, further bone loss, and ultimately failure of the FPD.

Abutment Evaluation – Periodontal Health – Crown to Root ratio Exception to Crown to root ratio guidelines:

If opposing occlusal forces are diminished such as: Artificial teeth (Full denture, RPD) Periodontally compromised opposing teeth

Abutment Evaluation – Periodontal Health – Root Configuration (3) root # wide/fused length

Multi-rooted teeth are better than single rooted teeth, conical teeth. Widely separated roots are better abutments than fused roots. Long roots are better abutments than short roots.

Single Rooted teeth –

Irregular configurations or curvatures are preferable compared to a perfect taper.

--- Facial-Lingual than Mesio-Distal preferred to round.

Broader

Ante’s Law :

The root surface area (embedded in bone) of the abutment teeth should be equal or surpass that of the teeth being replaced with pontics. **NOTE – these are comparative numbers.

Ante’s Law General principle –

any FPD replacing more than 2 posterior teeth has guarded prognosis -Maxillary arch has longer crowns and less tooth inclinations and therefore can occasionally be acceptable.

skipped Abutment Evaluation – Periodontal Health – Root Surface – Ante’s Law Shortcomings of Ante’s Law

Dr Shashikala Jain. 2011. Heal Talk -The suggested ratio cannot be made standard for all patients as individual variations in crown root ratio, root morphology and bone exist. -Occlusal scheme which is the key factor has not been considered at all. -Failure in FPD’s are more due to biomechanical factors like caries, gingival inflammation, poor framework design, poor occlusion and material failure than due to overstressing of periodontal ligaments. -Studies have revealed successful FPD’s supported by periodontally weakened teeth.

Abutment Evaluation – Periodontal Health – Root Surface – Ante’s Law Conclusion:

“Occlusion is the key to success. Even the worst cases with doubtful prognosis had good success rates when occlusion was right.”

skipped Abutment Evaluation – Path of Insertion

Axial walls of abutment teeth must be aligned without undercuts or interferences with path of insertion of the bridge. Tipped tooth? – can be very difficult to prepare effectively. -expose mesial pulp horn -unfavorable occlusal forces if tilt is too significant -Possible orthodontic uprighting prior to preparation

Abutment Evaluation – Path of Insertion – Use of Diagnostic Casts Casts can and should be used to

visualize the indications and contra-indications for FPD treatment.

Casts should be accurate (2)

--Alginate too dry or absorbed too much water create defects --Casts should be mounted with facebow if needed

skipped Using casts, you can evaluate: (6)

-Edentulous spaces and span length -Curvature of the arch -M-D drifting, rotations, F-L displacement of the abutments -Inclination -Occlusion and inter-occlusal space -Path of Insertion

Abutment Evaluation – Path of Insertion – Use of Diagnostic Casts When teeth are not perfectly aligned (which is nearly every time), a --- can be used to identify the path of insertion and to help you create the appropriate planes in tooth preparation to create a path of insertion.

surveyor

skipped Abutment Evaluation – Radiographs (6)

-Caries – Where and how much -RCT present?– is it healthy? -Bone levels – C:R ratio, direction of roots, PDL widened, bone loss -Thickness of soft tissue -Maxillary sinus **Should be within 6 months for fixed procedures.

Partially Edentulous Patient – Resin-bonded Fixed Partial Prosthesis -Also known as -Conservative --- only preparation

Marilyn Bridge enamel

Partially Edentulous Patient – Resin-bonded Fixed Partial Prosthesis -Used for -Only areas of -Not indicated for -Excellent option in -Most often used to replace missing

single missing tooth with slight to moderate tissue resorption in missing tooth area light occlusal stresses and good alignment with neighboring teeth deep vertical overlaps (Deep bite) younger patients where age contraindicates implant or bridge maxillary lateral incisors

Cantilever Fixed Partial Prosthesis

A fixed partial denture that has an abutment(s) at one end with the pontic remaining unconnected on the other end.

Partially Edentulous Patient – Selection of the type of Prosthesis. Options: Implant supported FPD Indications: (4)

-Implant abutments are soundly integrated -Implant parallelism -Availability of bone to support implant -Patient demonstrates adequate home care

Partially Edentulous Patient – Selection of the type of Prosthesis. Options: Implant supported FPD controversial – implant to tooth bridge -Can natural tooth handle implant stresses? Implant cantilever bridge --Clear Choice and others fabricate full arch one piece fixed appliance. --$25,ooo per arch --Patient cannot -- --- is a huge challenge here. --Need to be replaced around every -- years with current materials.

remove Hygiene 10

Partially Edentulous Patient – Selection of the type of Prosthesis. Options: Implant supported FPD Limitations of implant placement (3)

Amount of bone critical Location of bone critical Anatomy

Location of bone critical --- loading of implants needed for best prognosis and this can be difficult to achieve

Vertical

Anatomy (3)

--Maxillary sinus --IAN --Anterior angulation of bone