Pre Prosthetic Evaluation Guide

DIAGNOSIS AND
TREATMENT
PLANNING
PRE PROSTHETIC
EVALUATION

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INDIAN DENTAL ACADEMY
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Pre Prosthetic Evaluation
Intraoral examination
 Analysis of mounted study casts
 Bone mapping
 Radiographic analysis
 Force evaluation



Intraoral Examination
 Existing

occlusion
 Existing occlusal plane, orientation
 Interarch space
 Existing vertical dimension of
occlusion
 Maxillomandibular arch relations
 Temporomandibular joint status
 Existing prosthesis

Intraoral Examination
 Arch

form
 Ideal implant permucosal position
 Missing teeth location
 Missing teeth number
 Lip line at rest and during speech
 Mandibular flexure
 Soft tissue support

Arch form


Diagnostic Casts
Mounted diagnostic cast are invaluable
for Occlusal centric relation position
including premature occlusion
 Edentulous ridge relations to adjacent
teeth and opposing arches
 Position
of
potential
natural
abutments
including
inclination
rotation extrusion spacing parallelism
and esthetic considerations



Position of the replacement in
relation to the residual ridge


Diagnostic Casts
Direction of forces in future implant
sites
 Present occlusal scheme including the
presence of balancing or working
contacts
 Edentulous
soft tissue angulation,
length, width, locations, permucosal
esthetic position, muscle attachments
and tuberosities



Study Model Analysis –
Edentulous Patient
 Pattern

of resorption - can
exhibit as cross bite in posterior
region and as prognathism in
anterior region.
 Mounted study models will help
ascertain vertical and sagittal
relationships


Mounted study models indicating
minimum Interocclusal distance


Mounted Study models showing
large interarch space


Prognathic relationship


Angle class II


Study Model Analysis –
Partially Edentulous Patients


Interarch
Distances


Evaluation Of Available Bone
 Evaluation

of bone quantity
 Evaluation of bone quality


Available bone is evaluated by
Digital Palpation
 Radiographs
 Study models
 Bone sounding



Bone sounding


OSTEOMETER


MAINZ MEASURING GAUGE


EVALUATION OF BONE QUANTITY


ALVEOLAR PROCESS

FUNCTIONAL ADAPTATION


ATWOODS CLASSES OF RESORPTION
FOR MAXILLA


ATWOODS CLASSES OF RESORPTION
FOR MANDIBLE


Classification Of Degree Of Resorption Of
Edentulous Jaws By
Lekholm And Zarb(1985)


Pattern of resorption (Harle)
 Maxillary

arch buccal to lingual
 Mandibular arch lingual to buccal


Available bone is studied under
Height of bone
 Width of bone
 Length of bone
 Bone contour
 Crown implant
ratio



Height of bone
 Vertical

extent bone available for
implantation
 Distance between the crest of
alveolar bone to the opposing
anatomic structures


Width of bone
 Distance

between oral and vestibular
cortical plates
 1mm diameter increase = 20-30%
increase in the total surface area
 3mm increase in length provides
more than 10% increase in surface
area


Length of bone
 Minimum

distance between axis to
axis between two implants is 7mm
 R1+R2+2mm=distance between two
implants


Bone contour (Angulation)
 Favorable

bone contour is one in
which the functional and esthetic
demands of the prosthesis to be
borne by the implant can be
fulfilled with axial loading of the
prosthesis


Divisions of
Available bone quantity
 Division

A (abundant)
 Division B (barely sufficient)
 Division C (Compromised)
 Division D (Deficient)


Division A
 Width

> 5mm
 Height >10-13mm
 Length >7mm
 C/I < 1


Division B
 Width

2.5-5mm
 Height >10-13mm
 Length >12mm
 C/I < 1


Options for Division B Bone
 Modify

the existing Div B ridge to
another division by Osteoplasty
 Insert a narrow Div B root form
implant
 Modify existing Div B bone into Div A
by augmentation


Disadvantages Division B
 Stress

at the crestal region around
the implant is twice
 Lateral loads on the implant result in
almost 3 times greater stress than
Division A
 Fatigue fractures in the abutment
are increased
 Crown emergence profile is less
esthetic

Disadvantages Division B
 Conditions

around the cervical aspect
of the crown for daily care is poor
 Angle of load must be reduced to
less than 20 degrees to compensate
for the small diameter
 Two implants are required for proper
prosthetic support


Division C
 Unfavorable
 Unfavorable
 Unfavorable
 Unfavorable

Width (C-w)
Height (C-h)
Angulation (C-a)
C/I = 1


Treatment options for Division C
 Ostoeplasty
 Root

form implants
 Subperiosteal implants
 Augmentation procedures
 Ramus frame implants
 Transosteal implants


EVALUATION OF BONE QUALITY


Bone Quality Is Evaluated By
 Tactile
 Radiographic
 Biochemical


Bone density and success rates
 Adell

et al reported 10% greater
sucesss rate in the anterior mandible
compared to anterior maxilla
 Schnitman et al reported highest
success rate of 75% in the posterior
maxilla
 Friberg et al reported 66% of the
implant failures occurred in soft bone


CT determination of bone density
 D1:
 D2:
 D3:
 D4:
 D5:

> 1250 Hounsfield units
850 - 1250 Hounsfield units
< 150 Hounsfield units


Mechanostat theory of Frost
 The

structure of bone is maintained
by the micro strain environment
 Bone reaction to different degrees of
micro strains
0-50
: acute disuse window
50-1500
: adapted window
1500-3000 : mild overload
Above 3000 : pathologic overload

Bone Classification Related To Implant
Dentistry By Linkow (1970)
 Class

I Bone structure:

ideal type of bone with evenly spaced
trabeculae with small cancellated spaces
 Class

II Bone structure:

bone has larger cancellated spaces with
less uniformity of the cancellous spaces
 Class

III Bone structure:

large marrow spaces between trabeculae


BONE DENSITY
CLASSIFICATION BY MISCH
D1

Dense
cortical

D2

Porous
cortical

D3

Coarse
Trabecular


D4

Fine
trabecular

Bone density location
 D1

– 6% in anterior mandible
3% in posterior mandible
 D2 – most common in mandible
 D3 – most common in maxilla
65% in anterior maxilla
50% in posterior maxilla
 D4 – most common in posterior
maxilla

Influence Of Bone Density On Treatment
Planning
 Surgical

– Soft bone protocol
– Selection of fixture size
– Selection of the drilling sequence
– Selection of the material of the implant
– Auxiliary procedures
 Prosthetic

– Progressive loading

Evaluation of force
 Parafunction
 Position

of abutment in the arch
 Masticatory dynamics
 Nature of the opposing arch
 Direction of load forces
 Crown-Implant ratio


Thank you
Leader in continuing dental education


Pre Prosthetic Evaluation Guide

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Pre Prosthetic Evaluation Guide