Diagnosis and treatment planning in implants 2. / dental implant courses by Indian dental academy

Diagnosis and Treatment Planning-II.
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

• Pre implant
considerations
• Evaluation of
natural teeth
adjacent to
implant site
• Bone evaluation.
1. Existing occlusion.
2. Existing occlusal plane, orientation.
3. Interarch space
4. Existing vertical dimension of
occlusion.
5. Maxillomandibular arch relationship
6. Temperomandibular joint status
7. Existing prosthesis.
8. Arch form(anteroposterior distance).
9. Implant ideal permucosal position.
10. Missing teeth: location
11. Missing teeth: number
12. Lip line at rest and during speech.
13. Mandibular flexure.
14. Soft tissue support.
1. Abutment mobility
2. Pier abutment
3. Terminal splinted abutment.
4. Crown size
5. Crown-root ratio
6. Endodontic status
7. Root configuration
8. Tooth position
9. Parallelism
10. Arch position
11. caries
12. Periodontal status.

Pre implant considerations.
1. Existing occlusion.
2. Existing occlusal plane, orientation.
3. Interarch space
4. Existing vertical dimension of occlusion.
5. Maxillomandibular arch relationship
6. Temperomandibular joint status
7. Existing prosthesis.
8. Arch form(anteroposterior distance).
9. Implant ideal permucosal position.
10. Missing teeth: location
11. Missing teeth: number
12. Lip line at rest and during speech.
13. Mandibular flexure.
14. Soft tissue support.

Existing occlusion
• The relationship of centric occlusion to centric
relation is to be noted because.
– Of potential need of occlusal adjustments to eliminate
deflective tooth contacts.
– Evaluation of their potential noxious effects on the
existing dentition.
– For planned restoration.
• Correction may involve one or more of the
procedures.
1. Selective odontoplasty
2. Restoration with the crown (with or without Endodontic
therapy)
3. Extraction of the offending tooth.www.indiandentalacademy.com

Existing occlusal plane orientation
• Aids to evaluate the needed changes.
– Pretreatment diagnostic wax up.
– Occlusal plane analyzer.
Following changes can be seen in opposing dentition
– Drifting
– Tilting
– In partially edentulous ridge more facial resorption may
require implant insertion more medial in relation to the
original central fossa of the natural dentition.

• A proper curve of spee and curve of Wilson are
indicated for proper esthetics and to prevent
posterior lateral interferences during excursions.
• A steep incisal guidance may help avoid posterior
interferences in protrusive movements.
– If its shallow,it may be necessary to plan recontouring or
prosthetic restoration of any posterior offending teeth.
– A mesially tipped mandibular third molar may greatly
compromise the implant placed in the maxillary posterior
region.
• Remedy
– Odontoplasty
– Endodontic therapy,
– And /or extrusions of adjacent or opposing natural teeth.

Interarch space.
Type of
restoration
Anterior Posterior
Fixed 8-10 mm 7 mm
removable 12 mm. 12 mm

Increased space
• Results from vertical loss of alveolar bone and soft
tissues.
• Increased space makes the placement of
removable prosthesis easier.
• In fixed restorations increased space makes
– Replacement teeth elongated.
– Placement of gingival tone materials
– Increased crown height increased moment of
force on implants increased risk of component
and material fracture.

Management of increased
Interarch space.
• May be decreased by addition of onlay grafts
before implant placement.
– Autogenous and /or membrane grafts.
– Alloplastic grafts
• It improves
– Crown –implant ratio
– Esthetics
– Permits wider implant selection.
– Benefit of increased surface area.
– Improves hygiene condition.

Lack of Interarch space.
• Results from
– migration of the opposing natural dentition into the
edentulous space.
– History of tooth abrasion,attrition and skeletal
insufficiencies
– Even when the opposing teeth are extracted or missing
the Interarch space is still less as the alveolar process
has followed the teeth.
• Consequences.
– Decreased abutment height
– Inadequate retention.
– Inadequate bulk for esthetics and strength
– Poor hygiene conditions.www.indiandentalacademy.com

Management of less Interarch
space.
1. Surgical reduction of tuberosities.
2. Osteoplasty and /or soft tissue reduction
of implant region
3. Selective grinding
4. Prosthodontic restorations
5. Endodontic therapy.

Existing vertical dimension of
occlusion
• Patients who have been partially or fully
edentulous for several years may exhibit a
collapsed OVD.
• Assessment to be done as it influences
– Inter arch space
– Anteroposterior jaw relationship.
• Techniques used in traditional
prosthodontics can be used in this.

Maxillomandibular arch relationship
• An improper skeletal position may be
modified by orthodontics and/or surgery.

• Anterior edentulous maxilla decreases 40% within few
years at the expense of labial plate.
• Implants are placed lingual to original incisal position.
• Final restoration Is over contoured for
• Cantilevered force on the anterior implant body.
• To compensate for the increase in lateral loads and
moment of force
• additional implants
• increase in the anteroposterior distance between implants.
•Esthetics
•speech
•lip position
•occlusion.

• An anterior cantilever on implants in the mandibular
arch may correct an angle’s skeletal class II jaw
relationship.
• A complete denture cannot extend beyond the bone
support or neutral zone of the lips without decreasing
stability of the prosthesis.
• However implants can permit the placement of the
replacement teeth in a more ideal esthetic and
functional position.
• The anterior cantilever is dependent on the presence of
sufficient anteroposterior distance between the
implants.
• To counter the cantilever effect, the treatment plan
should provide increased implant support.

• Edentulous maxillary posterior arches resorb
towards the palate.
• Ridge is medial to the opposing mandibular tooth
central fossa.
• Posterior teeth may be placed in a cross bite to
decrease the moment of forces developing on the
maxillary posterior teeth.

Temporomandibular joint status
• Signs and symptoms of dysfunction.
– Pain
– Muscular tenderness
– Noise
– Clicking
– Limited jaw movements.
• Maximal opening is noted
– Normal 38-40 mm from maxillary incisal edge to
mandibular incisal edge.in angle’s skeletal class I
patient.

• Deviation on opening should be noted and
typically takes place on the same side as
symptomatic TMJ.
• The patient should be able to perform
unrestricted mandibular excursions.
• Patient should ideally be free of symptoms
before implant therapy can be considered.
• Many patient with soft tissue prosthesis and
TMJ dysfunction benefit from the stability
and exacting occlusal aspects the implant
therapy provide.

Existing prosthesis.
• Removable partial soft tissue –supported
restoration opposing the proposed implant
supported prosthesis.
• Occlusal forces will change once the implant
supported prosthesis will be placed
• Forces will vary as underlying bone remodels.
• Constant maintenance and follow up are
indicated, including reline and occlusal evaluation.

• Existing prosthesis which has to be replaced
with implant supported prosthesis.
– To be evaluated for Esthetics
– Contour arrangement and position of the teeth
are evaluated.
• Pretreatment prosthesis is indicated when
– Patient unsatisfied with esthetics
– TMJ dysfunction
– Poor soft tissue health
– Decreased OVD
– Collapse of posterior support.

• Acceptable preexisting maxillary removable
prosthesis is used as a template for implant
reconstruction.
• lip position and support provided by Labial
flange is evaluated .
• If support is less without flange, a
hydroxyapatite(HA) labial onlay graft is
usually indicated.

Arch form (anteroposterior distance)
• Edentulous arch forms are
1. Ovoid-most common.
2. Tapering-
found in class II skeletal patients as a result of Para functional
habits during growth and development.
1. Square.
• may result from initial formation of the basal skeletal bone
• Labial bone resorption of the premaxilla region when
anterior teeth are lost earlier than the canine and posterior
teeth.

• The distance from the center of the most
anterior implant to a line joining the distal
aspect of the two most distal implants is
called the anteroposterior distance or A-P
spread.
• It provides an indication of the amount of
cantilever that can be reasonably planned.

• The predominant factors to determine the cantilever
length are related to stress, not the A-P distance.
• Factors to determine length of cantilever.
• Parafunction (most important)
• Arch position
• Masticatory dynamics.
• Opposing arch
• Crown height
• Direction of force
• Bone density
• Implant number
• Implant width.
• Implant design
• A-P distance.

• The arch form is an important
determinant when anterior implants are
splinted together to cantilever the
restoration to the posterior regions.
• In this situation square arch form
provides poorer prognosis than the
tapered arch forms.
• As a general rule, when 5 anterior
implants in the mandible are used for
the prosthesis support, the cantilevered
posterior section of the restoration
should not exceed 2.5 times the A-P
spread when all stress factors are low.
Posterior cantilevered

Anterior cantilever
• In advanced anterior maxillary arch resorption the
implant may have to be placed at the canine
locations
• The resulting restoration is a fixed,anteriorly
cantilevered prosthesis when the original arch
form is restored.
• Greater stress results for tapered arch forms
compared with square arch forms all other factors
being identical.

• The cantilever to replace a tapered arch form
requires the support of additional implants of
greater width and number.
• In maxilla the recommended anterior cantilever
dimension is less than for the posterior cantilever
in the mandible as
– Bone is less dense
– Forces are directed outside the arch during excursions.

Implant ideal permucosal position.
• An implant placed in the improper position can
compromise the final results in esthetics
biomechanics and maintainnence.
• Use of surgical template for implant placement is
strongly suggested in most edentulous regions.
• It should provide both ideal implant permucosal
placement and angulations information.

Facial placement
• Results in compromised
– esthetics
Phonetics
Lip position
Function
• Angled abutment may help improve the condition.
• It increases the forces on the crest of the bone
Labial cortical plate is much thinner and hence
cervical bone loss is common in these conditions.

Lingually positioned.
• It is easier to correct in final restoration.
• Thicker lingual plate provides initial
stability
• As implant body is half the diameter of the
adjacent teeth, the final crown is not
necessarily over contoured on the lingual
aspect.

• An implant placed too far mesially or too distally
is of less consequence if lip does not expose the
cervical third of the restoration.
• The final restoration is constructed with the
interproximal incisal two thirds ideal for esthetics,
independent of implant placement.
• Hygiene is compromised, but the crown can be
designed to allow daily care.

Missing teeth: location
• The number and location of missing teeth
influences the prosthodontic treatment plan of the
patient.
• The second mandibular molar is not replaced in
posterior implant supported prosthesis.
• The mandibular first molar is designed to occlude
with the mesial marginal ridge of a natural second
molar to prevent extrusion.

Disadvantages of replacing mandibular
second molar.
1. 90% chewing efficiency is
forward of mid –first molar.
2. More lateral interferences in
occlusion.
3. 10% greater bite force.
4. Location of mandibular
canal.
5. Less dense bone.
6. Submandibular fossa is
greater.
7. Less Interarch space for
cement retention.
8. Less access to occlusal
screws.
9. Hygiene is more difficult.
10. Cheek biting is more
common.
11. Cross bite more often
necessary.
12. More incision line opening
post surgery.
13. Greater mandibular flexure.
14. Greater cost to patient.

Maxillary second molar implant
is mostly indicated because.
• Poor bone density in the region and need
for added posterior support.
• No risk of Paresthesia.
• Implants do not extrude especially when
they are splinted.

Missing teeth: number
• Independent implant restorations not connected to
teeth cause fewer complications and longer success.
• The number of posterior pontics in fixed restoration
should not extend beyond two, and even this
condition is improved with independent implant
supported restorations.
• Non precious metals deform approximately 50%
less than high noble alloys and therefore may be
selected for long span restorations supported by
teeth.

Lip line at rest and during speech.
• Following lip positions are evaluated.
– Resting lip line
– Maxillary high lip line
– Mandibular low lip line.
• It is recommended to make the patient
aware of these existing lip lines and impress
upon them that these lip positions will be
similar after treatment.

Resting lip line
• Especially noted if maxillary anterior teeth are to
be replaced.
• The resting lip positions are highly variable,but in
general are related to the patients age.
• Older patients show fewer maxillary teeth at rest
and during smiling but demonstrate more
mandibular teeth during sibilant sounds.
• Extending crown height in maxilla to decrease the
age of smile may result into increased moment of
forces.

Maxillary high lip line.
• It is determined while the patient displays a
natural, broad smile.
• If patient has high lip position during
smiling, the prosthodontic requirements are
more demanding
– Onlay grafts of HA may be indicated.
– Addition of pink porcelain.

Mandibular low lip line.
• It has to be observed during speech.
• In pronunciation of the “ s” sounds, or sibilants,
some patients may expose the entire anterior
mandibular teeth and gingival contour.
• Patients are often unaware of this preexisting lip
position and blame the final restoration for the
display of the mandibular gingiva, or complain
that the teeth look too long.

Mandibular flexure.
• The amplitude of the movement is 0.8 mm in
molar area and 1.5 mm in ramus area.
• As a consequence, complete cross-arch splinting
of posterior molar rigid, fixated implants is
usually contraindicated in the mandible
• Options
– Segment the restoration in 2 or more independent
prostheses.
– Non rigid connectors
– Insert posterior implants only in one section.

Soft tissue support
• Evaluation of soft tissue support is
primarily needed in planning for
overdenture prostheses.
• Shape of the ridge.
– Square: optimal resistance and stability.
– Flat: compromised factor for retention and
stability.support is adequate.
– Tapering ridges: poor stability.

• Ridge parallelism
– Rides parallel to occlusal plane : most
favourable
– Both ridges are divergent: stability of the
denture will be affected.

Evaluation of natural teeth
adjacent to implant site.
1. Abutment mobility
2. Pier abutment
3. Terminal splinted abutment.
4. Crown size
5. Crown-root ratio
6. Endodontic status
7. Root configuration
8. Tooth position
9. Parallelism
10. Arch position
11. caries
12. Periodontal status.

Decision making protocol for a
natural tooth abutment
Prognosis Protocol
>10 years Keep the tooth and restore as indicated.
5 to 10
years
Make an independent implant restoration. If
the natural tooth abutment must be
included,make it a “living pontic” by adding
more implants or splinting to additional teeth
with copings and a retrievable prosthesis
<5 years Extract the tooth and graft the site. Consider
an implant in the site after healing.

Abutment mobility.
• 4 important components may contribute
movement to the implant –tooth rigid
fixed prosthesis.
1. The implant
2. Bone
3. Tooth
4. The prosthesis and prosthetic component.

• Tooth exhibits normal physiological movement
in vertical horizontal and rotational directions.
• Amount of movement depends on
1. Roots
1. Surface area
2. design
3. Diameter
4. Shape
5. Position
2. Amount of surrounding bone.

Physiologic movement.
Healthy
posterior tooth
Rigid
implant
Fixed prostheses
Vertical
direction
Zero. Clinical
28 µm actual
2-3 µm
under 10 Ib
force.
Single pontic –6
µm.
Two pontic span 48
µm
Under 25 Ib force.
Horizontal
tooth
mobility
Anterior 90-108
µm
Zero clinical
Posterior 56-75
µm
11-66
labilingual
8-140 in
mesiodistal
direction

• There is extensive documentation that
implants can be connected rigidly to stable
teeth.
• However occlusion should be modified so
that implant does not bear the major
portion of the load.

• Visual clinical evaluation by the human eye can
detect movement above 90 µm.
• When mobility of natural tooth can be observed,it
is above 90 µm and too great to be compensated
by the implant,bone,and prosthesis movement.
• criterion for joining an implant to natural teeth
– is that there be no observable clinical mobility of the
natural abutment.
– No lateral forces should be designed on the implant.

• Implants should rarely be connected to anterior
teeth because
– Anterior teeth often exhibit greater clinical mobility than
the implant can tolerate.
– Lateral forces applied to the restoration during
mandibular excursions will be transmitted to the
abutments,implants included.
• When natural abutments show clinical mobility two
options are available.
– Place additional implants and avoid inclusion of natural
abutment.
– Splinting of additional natural abutment to improve
stress distribution and obtain 0 clinical mobility.

Pier abutment.
• When an implant serves as a pier abutment
between two natural teeth,the differences in
movement between implant and tooth may
be magnified.
• Implant act as fulcrum of class I lever.
• Leads to uncemented abutment and
subsequent decay.

• To prevent the implant pier abutment from
acting as a fulcrum, a non rigid attachment
may connect the implant and the least
retentive crown or most mobile tooth.
• An implant does not undergo mesial
movement during function,so the nonrigid
connector location can be more variable.

• When natural abutment is the pier abutment
between two implants, a stress breaker is
rarely indicated.
• The tooth may then act as living
pontic,contributing less to the support,
provided the number of pontics is limited
and the implants are of sufficient
dimension.

Crown size.
• The retention of a crown is influenced by the
diameter and height of the abutment.
• Crown height may be affected when Interarch
space is limited.
• Management of decrease d crown size.
– Splinting –improves retention but compromises access
for hygiene in the interproximal areas.
– Crown lengthening
– Minimal tapering
– Retentive elements such as grooves or boxes.

Crown-root ratio.
• The crown root ratio represents the height of the
crown from the most incisal or occlusal position to
the crest of the alveolar ridge around the tooth
compared with the height of the root within the
bone.
• Is important when lateral forces are expected
against the crown,as in mandibular excursions.
• The lateral forces develop a class I lever condition
on the tooth with fulcrum at the crest of the bone.
• Splinting may be indicated for better stress
distribution.

• Found rarely but most ideal crown root ratio
for a fixed prosthetic abutment is 1:2.
• Common condition 1: 1.5
• Minimum requirement. 1:1.
• Crown to root ratio when opposing natural
teeth or implants and when serving as an
abutment for an implant tooth prosthesis.

Endodontic status.
• A natural abutment included in a combination of
tooth and implant supported prosthesis should
present a satisfactory pulpal condition or a root
canal obturation.
• Exacerbation of Endodontic lesion after implant
surgery may result in adjacent implant failure.
• Some anterior teeth show wide incisal edges and
narrow cervical portions,especially if recession of
the gingiva has occurred.
• Pulpal exposure of the lateral horns are common
when preparing such teeth for full crownswww.indiandentalacademy.com

• Past periodontally involved teeth are more at
risk of pulpal disease after tooth preparation.
• Apicoectomy procedures ,when indicated
,are best performed without use of amalgam
retrograde filling to avoid corrosion
byproducts in the area, which may
contaminate metal implants.

Root configuration.
• Root configuration of a natural abutment may
affect the amount of additional stress the tooth
may withstand without potential complications.
• Favorable root configuration
– Dilacerations
– Curvatures of root.
• Unfavorable root configuration.
– Tapered
– Fused roots
– Blunted apices.
– Maxillary second molar often presents varied root
configuration

• Any adjacent natural tooth with curved roots at the
apex must be carefully evaluated before implant
placement.
• Maxillary canine is often tilted 11 degrees and
exhibits a distal curvature to its roots.
• An implant placed in the premolar region may
inadvertently placed into the canine root apex
when the topography of the area is not
appreciated.

• Roots with circular cross-section do not represent
as good a prosthodontic abutment as those with an
ovoid cross section.
• Therefore maxillary premolar is a better abutment
than the maxillary central incisor,although their
root surface areas are similar.
• Maxillary lateral incisor exhibit les lateral
mobility than central incisor,as a result of its
cross-sectional anatomy.

Tooth position.
• When adjacent teeth have been missing for
a long time ,the remaining natural abutment
has often drifted form its ideal position
• Tipping
• Tilting
• Rotation
• Extrusion.

• Correction of natural abutment should be
considered.
– Crown preparation
– Endodontic therapy before restoration
– Orthodontic movement.
• Orthodontic treatment can be planned in
conjunction with the healing phase for rigid
fixated implants.

Parallelism.
• Splinting incisor teeth is more common in implant
dentistry than traditional prosthodontics.
• Joining nonparallel teeth or splinting anterior and
posterior teeth in same prosthesis may be required.
• Several abutments may need Endodontic therapy
to achieve this goal.
• Selective extraction of incisors may even be
indicated if rotations or overlapping of teeth
represent unrealistic conditions for oral hygiene
after restoration.

• Indications for knife edged margin preparation for
a crown,
– Interproximal areas of incisors,so pulp horns are not
encroached upon
– Onside of tooth tipped more than 15 degrees
• Apply when splinting anterior teeth or nonparallel abutments.
– On an implant post much smaller than the emergence
profile of its crown
– In the furcation region of multirooted teeth.

Root surface area.
• Greater the root surface area of proposed
abutment tooth ,the greater the support.
• Teeth affected by periodontal disease lose
surface area and represent poorer support
elements for a prosthesis.
• For a maxillary first molar, bone loss to the
beginning of the root furcation corresponds
to a root surface area reduced by 30%.

• Ante’s law requires the root surface area of
the abutment teeth to be equal to or greater
tan that of the teeth replaced by the pontics
of the fixed restoration.
• Although originally presented without
research or documentation,it has withstood
the test of time and serves as a clinical
guideline.

Caries.
• All carious lesions should be eliminated before
implant placement,even when the teeth will be
restored with crowns after implant healing for the
final prosthesis.
• As implants most often require several months of
healing after initial placement,the progression of
decay may alter the final treatment plan and loss f
desired abutment.
• If Endodontic therapy becomes indicated
,obturation of the canals ideally should be
completed before implant surgery.

Periodontal status.
• The periodontal evaluation of natural abutments to be
connected to implants is identical to evaluation of other
fixed partial denture abutments.
• Adjacent implant sit e may be contaminated by bacteria
during periodontal surgery.
• Implant surgeon should decide if periodontal therapy is
indicated on the abutment teeth at the same time as
implant placement.
• Active infection should be kept to a minimum during
implant placement.
• If conditions of increased risk are present,tetracycline is
administered before implant surgery to decrease the
sulcular flora,which may contaminate the implant site.www.indiandentalacademy.com

Divisions of available bone
• Classification of available bone follows the
natural patterns of bone resorption in the
jaws.
• Each division presents unique surgical and
prosthetic approaches.

Misch and Judy (1985)
Mandible : by Atwood. Maxilla by fallschussel

other bone classifications.
• Cawood and Howell.
• Weiss and Judy 1974 classification of mandibular
atrophy and its influence on subperiosteal implant
therapy.
• Louisiana state university and Kent (1982)
classification of alveolar ridge deficiency designed
for Alloplastic bone augmentation.
• Zarb and lekholm (1985) residual jaw morphology
with the insertion of Branemark fixtures.

Available bone
• Available bone
describes the
amount of bone in
the edentulous area
considered for
implantation.
• It is measured in
height length
angulation and
crown –implant
body ratio.

Available bone height.
• The minimum height of available bone for
endoosteal implants is in part related to the
density of bone.
• The minimum bone height for predictable
long term Endoosteal implant survival
approaches 10mm.

• Height of available bone is measured from the crest of the
edentulous ridge to the opposing landmark. Which may be
A. Maxillary canine region
B. Floor of the nares
C. Maxillary sinus
D. Tuberosity
E. Mandibular canine region
F. Anterior mandible
G. Bone above the inferior mandibular canalwww.indiandentalacademy.com

Available bone width.
• It is measured between the facial
and lingual plates at the crest of
the potential implant site.
• Root form implants of 4.0 mm
crestal diameter usually require
more then 5.o mm of bone to
ensure sufficient bone thickness
and blood supply around the
implant for predictable survival.

Available bone length.
• The mesiodistal length of avialble bone in an
edentulous area is often limited by adjacent teeth
or implants.
• For a bone more tan 5 mm wide, a minimum
mesiodistal length of 7 mm is usually sufficient
for each implant.
• For bone less than 5 mm requires a 3.2 mm
implant with compromises such as less surface
area and greater crestal concentration of stress.

Available bone angulation.
• Ideally it is aligned with the forces of
occlusion and is parallel to the long axis of
the prosthodontic restoration.
• The alveolar one angulation represents the
root trajectory in relation to the occlusal
plane.
• Rarely does this bone angulation remain
constant after the loss of teeth.

• Maxillary anterior region
– Maxillary anterior teeth are angled more to
occlusal forces than any other teeth.
– Labial undercuts and resorption after tooth loss
mandate greater angulation of the implants.
• Posterior mandibular region.
– Submandibular fossa mandates implant
placement with increasing angulation as they
progress distally.
– Second premolar region –10 degrees
– First molar region –15 degrees
– Second molar region –20-25 degrees.

• In edentulous areas with a wide ridge,
– wider root form implants may be selected.
– Decreases the amount of stress transmitted to the crestal
bone.
– Such implants allow modifications up to 30 degrees
divergence.
• Narrow yet adequate width ridge.
– Requires narrower design root form implant.
– Smaller diameter designs cause greater crestal stress and
may not offer the same range of custom abutments.
– The limits of the acceptable angulation of bone in narrow
ridge to 20 degrees from the axis of the adjacent clinical
crowns or a line perpendicular to the occlusal forces.

Crown –implant body ratio.
• The crown –implant body ratio impacts the
appearance of the final prosthesis and the amount
of moment of force on the implant and
surrounding crestal bone.
• The greater the crown height,the greater the
moment force or lever arm with any lateral force.
• As the crown-implant ratio increases,the number
of implants and/or wider implants should be
inserted to counteract the increase in stress.

Divisions of available bone.

Division A(abundant bone)

Division B (Barely sufficient
Bone)

• Division B ridge may be
converted to division A by
augmentation or
Osteoplasty.
• the augmentation requires 4
to 6 months but can result in
improved crown – implant
ratio and more natural
looking abutments.
• Implants may be placed at
the same time as
Osteoplasty,but the crown-
implant ratio is increased.

Division C (compromised bone)

Division D (Deficient bone)

Bone density.
• Linkow (1970)
• Class I bone structure
– The ideal bone type consists of evenly spaced trabeculae
with small cancellated spaces.
– Very satisfactory foundation for implant prosthesis.
• Class II bone structure
– The bone has slightly larger cancellated spaces with less
uniformity of the osseous pattern.
– Satisfactory for implants
• Class III bone structure.
– Large marrow filled spaces exist between bone
trabeculae.
– Results into loose fitting implants.www.indiandentalacademy.com

• Lekholm and zarb(1985)
• Quality 1
– Homogeneous compact bone
• Quality 2
– Thick layer of compact bone surrounding a core of dense
trabecular bone.
• Quality 3
– Thin layer of cortical bone surrounding dense trabecular
bone of favorable strength.
• Quality 4
– Thin layer of cortical bone surrounding a core of low
density trabecular bone.

Misch bone density classification
• D1 dense cortical bone
• D2 thick dense to
porous cortical bone on
crest and coarse
trabecular bone within.
• D3 thin porous cortical
bone on crest and fine
trabecular bone within.
• D4 fine trabecular
bone
• D5 immature,
nonmineralized bone.www.indiandentalacademy.com

Factors of stress
• Normal forces exerted on teeth.
• Bite forces
– Perpendicular to occlusal plane
– Short duration
– Brief total period (9 min/day)
– Force on each tooth : 20 to 30 psi
– Maximum bite force: 50 to 500 psi
• Peri oral forces.
– More constant
– Lighter
– Horizontal
– Maximum when swallowing (3 to 5 Psi )
– Brief total swallow time (20 min/day)www.indiandentalacademy.com

• Dental factors that affect stress primarily
include.
1. Parafunction
2. The position of the abutment in the arch
3. Masticatory dynamics
4. The nature of the opposing arch
5. The direction of load forces
6. The crown –implant ratio.

Parafunction.
• The most common cause of early loss of rigid
fixation during the first year of implant loading is
the result of Parafunction.
• Such complications occur with greater frequency
in the maxilla because of a decrease in bone
density and an increase in the moment of force.
• Parafunction may be categorized as absent,mild
moderate or severe.

bruxism
• It is the vertical and horizontal ,or
nonfunctional grinding of teeth.
• Bruxism does not necessarily represent a
contraindication for implants but it
dramatically influences the treatment plan.
• Best way to diagnose is the to evaluate the
wearing of teeth.

Clenching
• It is the force exerted from one occlusal
surface to the other without any movement.
• The forces are directed more vertically to
the plane of occlusion,at least in the
posterior regions of the mouth.
• Wearing of the teeth is not likely.
• Common clinical finding is the scalloped
border of the tongue.

Tongue trust and size.
• Parafuctional tongue thrust is the unnatural
force of the tongue against the teeth during
swallowing.

Position of abutment within the
arch.
• Biting force is greater in molar region and
decreases as it progresses anteriorly.

Masticatory dynamics
• Masticatory muscle dynamics are
responsible for the amount of force exerted
on the implant system.
• Forces recorded in woman are 20 lb less
than those in men.
• Younger patients need additional implant
support for the prosthesis for the longer
time.

Opposing arch
• Natural teeth transmit greater impact forces
through occlusal contacts than do soft tissue
borne complete dentures.
• Partial denture patients may record forces
which are intermediate between that of
natural teeth ad complete dentures and
depends on the location and condition of the
remaining teeth,muscles ,and joints.

Diagnosis and treatment planning in implants 2. / dental implant courses by Indian dental academy

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