Diagnosis and treatment planning in implant dentistry

Diagnosis And Treatment
Planning in Implant Dentistry
DR. LAJU. S
Associate professor , Malabar dental college
Edappal

Contents
• Introduction
• Medical history
• Dental history
• Intra oral examination and its significance
• Study model analysis
• Radiographic analysis
• Stress treatment theorem
• Prosthesis design
• Patient force factors

• Bone density
• Key implant position and number
• Implant size
• Available bone
• Implant design
• references

Introduction
• Successful implant rehabilitation is a complex and
multidisciplinary treatment modality . The success of it
depends on proper diagnosis of the underlying medical
and dental status of the patient and to modify the
treatment plan according to the needs of the patient

Successful diagnosis and treatment
planning
Medical &
Dental intra oral study Radiographs
History examination model
Previous
prosthesis,
esthetic
desire
Soft tissue,
bone, natural
teeth
diagnostic
wax up, smile
line
Bone volume ,
bone density
Type of prosthesis

Stress treatment theorem
Treatment planning
• 1. prosthesis design
• 2. Patient force factor
• 3. bone density in implant site
• 4. Key implant position and number
• 5. Implant size
• 6. Available bone
• 7. implant design

History.
• It is designed to provide an accurate
profile of how the patient’s quality of life is
being affected by tooth loss.
• It consists of 3 elements
– medical
– dental
– personal

Medical assessment
• It comprises of
– Vital signs
– Laboratory evaluation
– Systemic diseases

Vital signs
• Blood pressure
• Pulse
• Temperature
• Respiration.

Biochemical profiles(Serum
chemistry).

• Interpretation of biochemical profiles
and the ability to communicate
effectively with medical consultants will
enhance the treatment of many patient

Laboratory Evaluation
Complete blood cell count
1. RBC count
2. WBC count
3. WBC differential.
4. Hemoglobin
determination
5. Platelet count.
Bleeding tests.
1. Platelet count.
2. Bleeding time
3. Partial thromboplatin time.(PTT)
4. Prothrombin time(PT)
 Additional tests
 Fibrinogen level.
 Thrombin clotting time (TCT)
Biochemical profiles.
Serum glucose
Serum calcium
Inorganic phosphorous.
Alkaline phosphatase.
Creatinine.
Bilirubin

Classification of Pre surgical Risk.
• Formulated by American society of anesthesiology.
Class I Patients who are physiologically normal
Has no medical diseases
Lives a normal daily lifestyle.
Class II Patients who have some type of medical disease but
the disorder is controlled with various
medications.the patient can thus engage in normal
daily activity. E.g. Controlled hypertension.
Class III Patient who has multiple medical problems,such as
advanced –stage hypertensive cardiovascular
disease or insulin dependent diabetes with impaired
normal activity

Class
IV
Serious medical condition requiring immediate
attention. E.g acute Gallbladder disease.
Class V Patient is usually Morbidand and will not
survive the next 24 Hours.
Most patients who seek implant reconstruction fall in
class 1 or II categories.
Same patients fall in Class III and preparatory measures
have to be taken before treatment.

Systemic diseases
Cardiovascular diseases.
Hypertension.
Angina pectoris.
Myocardial infarction.
Congestive heart failure.
Sub acute bacterial endocarditis.

Implant management.
• Stress reducing protocol
• As anxiety greatly affects blood pressure.
• Flurazepam 30mg or diazepam 5 to 10mg
in the evening to help the patient sleep
quietly night before the operation.
• An early appointment.as medication may
still be effective in elderly.
Hypertension

Angina pectoris.
• Angina pectoris or chest pain or cramp of
the cardiac muscle, is a form of coronary
heart disease.
Angina pectoris

• Dental emergency kit should include
nitroglycerin tablets (0.3 to 0.4 mg) or
translingual spray
• During angina attack all dental
treatment should e stopped
immediately.
• Nitroglycerin is administered
sublingually
• 100% oxygen given at 6L/min with the
patient in a semi supine or 45 degree
position.
Angina pectoris

• Vital signs should be monitored as
Transient hypotension can occur after
nitroglycerin administration.
• If systolic BP falls below 100mm Hg
patients feet should be elevated.
• Pain if not relived in 8 to 10 minutes
with the use of nitroglycerin at 5 minute
intervals, the patient should be
transported by ambulance to a hospital.
Angina pectoris

Subacute bacterial Endocarditis.
• Bacterial endocarditis is an infection of the heart
valves or the endothelial surfaces of the heart.
• Results from growth of bacteria on damaged
/altered cardiac surfaces.
• Organisms most often associated in dentistry.
• Alpha-hemolytic streptococcus viridans
• Sometimes staphylococci and anaerobes.
• Mortality rate is about 10%.

• Scaling and root planning before soft tissue
surgery reduces the risk of endocarditis.
• Chlorhexidine painted on isolated gingiva or
irrigation of the sulcus 3 to 5 minutes before
tooth extraction reduces post extraction
bacteremia.
SABE*

Diabetes mellitus
• Diabetes mellitus is related to an absolute or
relative insulin insufficiency.
• It is the most common metabolic disorder

Diabetic patients are subject to greater
incidence and severity of
• Periodontal disease
• Dental caries due to xerostomia
• Candidiasis
• Burning mouth
• Lichenoid reactions.
• Increased alveolar bone loss
• Inflammatory gingival changes.
• Tissue abrasions in denture wearers oxygen tension
decreases the rate of epithelial growth and decrease tissue thickness.
Diabetes mellitus*

Implant protocol.
• Most serious complication during implant
procedure is hypoglycemia.
• It can be due to
– Excessive insulin level
– Hypoglycemic drugs
– Inadequate food intake.
Diabetes mellitus*

Thyroid disorders.
• Affects proximately 1% of general
population, primarily woman.
• As the vast majority of patients in implant
dentistry are woman, a slightly higher
prevalence of this disorder is seen in the
dental implant practice.

Potential implant patients.
• Patients with hyperthyroidism are sensitive to
epinephrine in LA and gingival retraction cords.
• Exposure to catecholamines (LA)+ stress+tissue
damage(implant surgery)

Adrenal gland disorders.
• Epinephrine and nor epinephrine are
produced by the cells of adrenal medulla.
• These hormones are responsible for the
– Control of blood pressure.
– Myocardial contractility and excitability.
– General metabolism.

• It corresponds to the decrease in the adrenal
function.
• Dentist can notice hyper pigmented areas on
the
• face
• lips
• gingiva.
• These patients cannot increase their steroid
production in response to stress and in the
midst of surgery may have cardiovascular
collapse.
Addison’s disease
Adrenal gland disorder

• Corticosteroids are potent anti-inflammatory
drugs used to treat a number of systemic
diseases and one of the most prescribed
drugs in medicine.
• Continued administration of exogenous
steroids suppress the natural function of the
adrenal glands.
• Therefore patients under long term steroid
therapy are placed on the same protocol as
patients with hypo function of the adrenal
gland.

Potential implant patient
• Whether hypo or hyper functioning a patient
with adrenal gland disease face similar problems
related to dentistry and stress.
• Their body is unable to produce increased levels
of steroids during stressful situations and
cardiovascular collapse may occur.
• Additional steroids are prescribed just before
surgery and stopped within 3 days.

• Steroids in implant surgery patient.
– Decrease inflammation,swelling and
related pain.
– Also decrease protein synthesis and delay
healing.
– Decrease leukocytes and therefore reduce
ability to fight infection.
• Therefore antibiotics are always
prescribed whenever steroids are given
to patients for surgery.

Bone diseases.
• Diseases of the skeletal system and
specifically the jaws often influence
decisions regarding treatment in the field
of oral implants.
• Bone and calcium metabolism are
directly related.

Osteoporosis.
• Most common disease of bone
metabolism
• Its an age related disorder
characterized by a decrease in bone
mass and susceptibility for fracture.
• Above 60 years one third of population
is affected.
• Denture is less secure and patient may
not be able to follow the good diet.

• Osteoporotic changes in the jaws are similar
to other bones in the body.
• The structure of bone is normal; however due
to uncoupling of the bone
resorption/formation process with emphasis
on resorption,
– the cortical plates become thinner,
– the trabecular bone pattern more discrete,
– and advanced demineralization occurs.
Osteoporosis

Osteomalacia.
• Caused by the deficiency of vitamin D in
adults.

• Oral findings
– Decrease in trabecular bone
– Indistinct lamina dura.
– Increase in chronic periodontal disease.
• Treatment is similar to osteoporatic
patient.
• Implants are not contraindicated.
Osteomalacia

Hyperparathyroidism.
• Oral changes occur in advanced disease
– Loss of lamina dura
– Loose teeth.
– Ground glass appearance of trabecular bone.
• Implants are not contraindicated if no bony
lesions are present in the region of the implant
placement.

Fibrous dysplasia.
• It is a disorder in which fibrous connective
tissue replaces areas of normal bone.
• Twice as common in woman and in maxilla.
• It may affect single bone or multiple bone.
• In jaws it begins as a painless, progressive
lesion.

• Implant dentistry is contraindicated in
the regions of this disorder.
• Lack of bone and increased firous
tissue
– Decreases rigid fixation.
– Susceptible to local infection processes.
• Excision of fibrous dysplasia is
treatment of choice.
• Excised area may receive implant in
long term.
Fibrous dysplasia

Paget’s disease
(Osteitis Deformans).
• Is a slowly progressing chronic bone disease.
– More common in men and those over 40 years of
age.
– Jaws are affected in 20% of cases.
– Maxilla is more often involved.
• Symptoms
– Tooth mobility
– Discomfort in wearing prosthesis.
– Bony enlargements can be palpated
– Spontaneous fractures.

• There is no specific treatment.
• Patients are predisposed to development
of osteosarcoma.
• Oral implants are contraindicated in the
regions affected.
Paget’s disease

Use of tobacco.
• There is established relationship
between smoking and…
1. ..Periodontal attachment loss.
2. ..Bone loss.
3. ..decreased resistance to
1. Inflammation.
2. Infection.
4. ..Impaired wound healing.
5. ..Reduced mineral content in bone in
1. aging smokers
2. Postmenopausal female smokers.

• Lower success of endosteal implants in
smokers.
• Failure
• is more in maxilla.
• When incision line opening after surgery
occurs, smokers will
– delay the secondary healing,
– contaminate a bone graft,
– and contribute to early bone loss during initial
healing.
• Smokers should be told of detrimental effect
on their treatment.
• Should be encouraged to start a smoking
cessation program.
Tobacco

Pregnancy.
• Implant surgery procedures are
contraindicated in pregnant patient.
• Reasons for postponement.
– Radiographs
– Medications
– Surgery
– Stress

Dental History
• Unstable or loose denture
• Inability to masticate efficiently
• Pain
• TMJ disorders
• Difficulties with speech
• Gagging
• Ulceration and soreness of mucosa

• Dental examination should include
extra oral and intra oral
• Extra oral : TMJ and Muscles of
mastication are examined for
anatomical abnormalities , sign of
infection and pathology
• Facial profile and lip support , with and
without any existing denture , needs to
be carefully evaluated and atypical
features noted
• Smile line relate to the level of upper
and lower lips in relation to the
corresponding gingival margin it is of
particularly importance in cases in
which gingival defect and long teeth
are included in the smile

Intraoral examination and its significance
1. Existing occlusion.
2. Existing occlusal plane, orientation.
3. Interarch space
4. Existing vertical dimension of occlusion.
5. Maxillomandibular arch relationship
6. Existing prosthesis.
7. Arch form(anteroposterior distance
8. Missing teeth: location
9. Missing teeth: number
10. Lip line at rest and during speech

11. Health of the remaining teeth
12. Assessment of oral hygiene
13. Parafunctional habit
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

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.

Management of less Interarch space.
1. Surgical reduction of tuberosities.
2. Osteoplasty and /or soft tissue reduction
of implant region
3. Selective grind
4. 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.
•Esthetic
•speech
•lip position
•occlusion.

• 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.

• 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.
3. 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.

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
labiolingual
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 can
be connected
• 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.

• Most ideal crown root ratio for a fixed
prosthetic abutment is 1:2.
• Common condition 1: 1.5
• Minimum requirement. 1:1

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 crowns

• 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 less 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.

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 than 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 of
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.

Diagnostic imaging
• Diagnostic image and technique helps develop and implement a
cohesive and comprehensive treatment plan for the implant
placement. Imaging can be done in 3 phases
• 1. Phase 1 – Presurgical or preprosthetic imaging
• 2. Phase 2 - Intra operative implant imaging
• 3. Phase 3 – Post prosthetic implant imaging

Objective of preprosthetic imaging
• To rule out the presence of disease at the proposed surgery site
• To determine the bone quality
• To determine the bone quantity
• To evaluate the relationship of critical structures to the prospective
implant site
• To determine the position and orientation of the implant

Intraoperative imaging
• To verify positioning and location of the osteotomy site or
for identification of a vital structure
• Assist in the optimal position and orientation of dental
implants,
• Ensure that abutment position and prosthesis fabrication
are correct

Post prosthetic Imaging
• A post prosthetic radiographs needs to be taken to act as a base
line for future evaluation of component fit verification and also for
marginal bone level evaluation
• It helps to investigate any complications after implant placement

Types of imaging modalities
• Periapical radiography
• Digital radiography
• Panoramic radiography
• Occlusal radiography
• Cephalometric radiography
• Tomographic radiography
• Computed tomography
• Magnetic Resonance Imaging

Periapical Radiography
Advantages : Low radiation dose
Minimal magnification with proper alignment
and positioning
High resolution
Inexpensive
Limitations : Distortion and magnification
minimal site evaluation
difficulty in film placement
technique sensitive
lack of cross sectional imaging

Digital radiography
• Digital radiology is an imaging
process wherein the film is
replaced by a sensor that
collects the data
• The analog information
received is then interpreted by
specialized soft ware, and an
image is formulated on a
computer moniter

• Advantages : less radiation
• high resolution
• less time consuming
• images can be formed during implant
placement and the prosthetic verification of component
placement is possible
• Disadvantages : size and thickness of the sensor and
and the position of the connecting cord. These features
make the positioning of the sensor more difficult in some
sites such as those adjacent to tori or a tapered arch
form in the region of the canine

Panoramic radiograph
• Advantages : Easy identification of opposing landmark
• Initial assessment of vertical height of bone
• Convenience, ease and speed in
performance in most dental offices
• Evaluation of gross anatomy of the jaws
and any related pathologic findings
• Limitations : Distortion inherent in panoramic system
• Errors in patient positioning
• Does not demonstrate bone quality
• Misleading quantitative because of
magnification and no third dimension
• No spatial relationship between structures
• Non uniform magnification , distortion and overlapping
images

• To overcome the limitation of
the OPG such as non uniform
magnification , distortion , etc ,
the following formula helps in
calculating the true amount of
clinically available vertical
bone at the planned implant
site
• Actual ht of available bone =
radiographic ht of available
bone * actual diameter of steel
sphere
radiographic diameter of
steel sphere

Occlusal radiography
• Advantage : Evaluation for
pathology
• Limitations : Does not reveal
true buccolingual width in
mandible
• Difficulty in
positioning
• Occlusal radiographs have
been postulated to show the
width of the bone in the
anterior region. However
usually this type of rediographs
show the widest buccolingual
distance . (red line)
• Actual width of bone (green
arrow)

Lateral cephalometric images
• Advantages : To evaluate the
height and width in anterior
region
• Low magnification
• Skeletal relationship
• Crown- Implant ratio
• Tooth position in prosthesis
• Evaluation of quantity of bone
in the anterior region prior to
symphysis grafting

• Limitations : Image information limited to midline
• Reduced resolution and sharpness
• technique sensitive

Tomographic radiography
• Advantages : Cross sectional
views of limited
anatomical section
• Constant
magnification
• provide 3
dimensional images
• Limitations : Cost
• Multiple images
needed for
viewing large areas
• Technique sensitive
• Blurred images
• High radiation dose

Computed tomography
• Advantages : Negligible
magnification
• Relatively high
contrast images
• Various views
• Three dimensional
bone models
• Interactive treatment
planning
• Cross referencing
• No superimposition
and overlapping of
images
• minimal distortion of
image
• Limitations : Cost
• Technique sensitive

Magnetic resonance imaging
• Advantage : No radiation
• Vital structures are easily seen
• Limitation : cost
• technique sensitive
• no reformatting software
• availability
• it is not useful to see bone mneralisation
• Uses : evaluation of vital structures when computed
tomography is not conclusive
• Evaluation of infection
•

Computer guided technology
• Surgical planning software and computer guided implantology
allows for the interactive use of CT data combines the 3 –
dimensional accuracy of CT imaging with computer aided design . It
enables precise pre operative assessment . If an appropriate
radiographic orientation device has been used at the time of
scanning , surgical guides can be constructed by CAD/ CAM
technology. This allows the operator to plan the case , place virtual
implants and then construct a surgical guide to aid implant
placement

Study model
• Articulate study models in
order to obtain informations
like
• 1. occlusal centric relation; any
premature occlusal contact
• 2.edentulous ridge relationship
to adjacent teeth and opposing
arches
• 3.Interarch space
• 4.Position of adjacent teeth
including inclination, rotation
,extrusion, spacing,parallelism
and esthetic considerations

• Direction of force in future
implant sites
• Diagnostic wax up can be
done on study models which is
used to fabricate radiographic
templates and surgical
templates
• Occlusal scheme can be
assessed
• Individual tooth relation , tooth
morphology , arch relationship,
interarch space can be
assessed
• Helps to analyze esthetic
outcome of the patient

• Bone mapping can be done in
diagnostic cast which provide
an idea about the buccopalatal
or buccolingual width of the
residual alveolar bone

Diagnostic / Surgical stent
• Diagnostic stent should be
fabricated on it with clear
acrylic material. The planned
implant site will be filled with
radiopaque material for CT
scan or steel sphere for OPG
• Diagnostic stent must be worn
by the patient during
radiographic examination
• The purpose of the diagnostic
radiographic template is to
incorporate the pt’s proposed
treatment plan into
radiographic examination

Surgical template
• Usually radiographic templates
are converted into surgical
template which helps to decide
probable implant location and
angulation. The diagnostic
stent can be converted into
surgical stent by making a
hollow space over planned
implant site.

• This stent helps in implant placement at exact location
so as to ensure the restoration of esthetics, speech and
function

Prosthesis design
Prosthetic options for implant dentistry
Misch in 1989

FP1
• An implant is positioned
in the maxillary rt canine
position
• The hard and soft tissue
conditions are ideal for a
crown of normal and size

• The maxillary rt canine
implant crown in place
• Soft tissue drape is
similar to natural tooth
• And the crown contour is
similar to the clinical
crown contour of a
natural tooth
• This is the goal of an FP1
prosthesis

• This full arch FP1
prosthesis has posterior
crown contours that are
narrower than natural
tooth, because the
implant is smaller in
diameter than the tooth
• As a general rule, the
maxillary arch has
reduced lingual contours
and the mandibular
posterior has reduced
buccal contours

• The bone and soft tissue
must be ideal in volume
and position to obtain an
FP-1 appearance for the
final restoration
• When multiple teeth are
replaced , bone and
tissue augmentation is
usually required to obtain
an FP-1 prosthesis

FP-2
• An FP-2 prosthesis has
longer clinical crowns
than healthy natural teeth
• Soft tissue drape is also
reduced around the
prosthesis

• The high maxillary lip line
is noted before the
fabrication of the
prosthesis
• When the upper lip during
smile does not expose
the interdental papillary
region , an FP-2
prosthesis may be
fabricated

FP-3
• There are basically 2
approaches for an FP-3
prosthesis
• 1. a hybrid restoration of
denture teeth and acrylic
and metal substructure
• 2. porcelain – metal
restoration

• Panoramic radiograph of
the same prosthesis

• The hybrid restoration of
denture teeth and acrylic
and metal substructure is
used in cases where
there is crown height
space is more than 15mm
from the bone to the
occlusal plane

RP-4
• An RP-4 restoration is a
removable prosthesis ( usually
an overdenture) that is
completely supported by
implant , teeth or both
• The restoration is rigid when
inserted; overdenture
attachments usually connect
the removable prosthesis to a
low profile tissue bar or
superstructure that splints the
implant abutments

• Usually 5 or 6 implants in
the mandible and 6to 8
implants in the maxilla
are required to fabricate
completely implant
supported RP-4
prosthesis
• The implant placement
criteria for an RP-4
prosthesis is different
than that for a fixed
prosthesis

• Denture teeth more acrylic are
required for the removable
restoration
• In addition , a superstructure
and overdenture attachments
must be added to the implant
abutment
• This requires a more lingual
and apical implant placement
in comparison with the implant
position for a fixed prosthesis

• The implants in an RP-4 , FP-2,and FP-3 prosthesis,
should be placed in mesiodistal position for the best
biomechanical and hygienic situation

RP-5
• RP-5 is a removable
prosthesis combining
implant and soft tissue
support
• The amount of implant
support is variable

• The completely edentulous mandibular overdenture may
have
• 1. two anterior implants independed of each other
• 2. Splinted implants in the canine region to enhance
retention
• 3. three splinted implants in the premolar and central
incisor area to provide lateral stability
• 4. implants splinted with a cantilevered barto reduce soft
tissue abrasion and to limit soft tissue coverage needed
for prosthesis support

Patient force factors
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)

• 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
to evaluate the wearing of
teeth.

• The incisal guidance for a
patient with moderate to
severe bruxism should be
shallow to reduce the force on
the anterior teeth during
excursive movement of the
mandible

• Treatment plan is modified in two ways
• 1. additional implants that are wider in diameter are one
method used to reduce the overload risk
• 2.anterior teeth may be modified to recreate the proper
incisal guidance and avoid posterior interferences during
excursions
• 3. eliminate posterior lateral occlusal contact during
excursive movement

Clenching
• It is the force exerted from one
occlusal surface to the other
without any lateral 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 findings are
the scalloped border of the
tongue, and abfraction of the
cervical margin of the teeth

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

• 6 types of tongue thrust are noticed
• 1. anterior
• 2. intermediate
• 3. posterior
• 4. unilateral
• 5. bilateral
• 7. combination

• These forces are horizontal in nature
• Cause harm to permucosal area of the implant
• May contribute incision line opening which may
compromise healing of soft tissue and hard tissue
• May lead to tooth or implant mobility

Prosthodontic considerations
• Reduce the width of the lingual contour of the
mandibular teeth
• Lingual cusp of the mandibular posterior teeth should
follow the curve of wilson

Masticatory dynamics
• Masticatory muscle dynamics are responsible for the
amount of force exerted on the implant system.
• Several criteria are included under this heading : patient
size, gender, age, skeletal position
• Larger patient generally have greater bite force
• 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.
• Pt with stout head shape may generate three times more
bite force compared with regular head shape

Arch position
• Biting force is greater
in molar region and
decreases as it
progresses anteriorly.
• Dense bone has
greater resistance to
stress
• Anterior mandible has
greater resistance to
stress because of its
density

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 and complete dentures and
depends on the location and condition of
the remaining teeth,muscles ,and joints.

• As a general rule, the
greater number of
opposing teeth, the
greater bite force. When
the opposing arch is a
denture , the bite force
are less

• When the opposing arch
has a fixed implant
prosthesis, the bite force
are greatest. The
decrease in
proprioception results in
higher force during
function and
parafunction.In this pt
cantilever should be
reduced significantly,
especially because the
crown height is also large

• Opposing arch consist of
natural teeth. Cantilever
length should be reduced
or the number of implants
increased , compared
with an edentulous
opposing arch

Crown height space
• Crown ht space is measured
from the occlusal plane to the
crest of the bone

• CHS acts as a vertical
cantilever
• The FP3 Prosthesis on the
right will deliver greater
stresses to the implant
compared with the FP1
prosthesis

• In the past tt plan included
more implants in the abundant
bone and fewer implants in the
less available bone . This
approach created
unfavourable mechanics
• Crown Height is a force
magnifier to any lateral load.
There for when available bone
ht decreases , more implant
should be inserted and
cantilever length should be
reduced

• Ideally CHS needed for a fixed implant restoration is 8-
12mm . This measurement includes biological width,
abutment ht, restoration, esthetics and hygienic
considerations around the implant
• Removable implant prosthesis require CHS greater than
12mm for the denture teeth, acrylic resin base,
attachment bar, and hygienic considerations

Methods to reduce the stress in increased crown
height space conditions
• Increase implant number
• Increase implant diameter
• Increase the surface area design
• Splint implant together
• Shorten cantilever
• Consider removable restoration
• Obtain soft tissue support in overdenture
• Minimize offset load to the buccal and lingual
• Remove removable prosthesis during sleeping to decrease the
effect of nocturnal parafunction

Bone density
• Internal structure of the bone is described in terms of
quality or density which shows the strength and the
elastic modulus of the bone
• Density of the bone is directly proportional to the
strength and modulus of elasticity of the 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.

• 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.

• Misch in 1995 found that stress is different for each bone
density. With same load , the stress for different bone
quality is as follows:
• D1 – crestal stress and lesser magnitude
• D2 – Greater crestal stress and along implant body
• D3 - same
• D4 – greatest stress and farther apically

• The percentage of bone at the implant interface is
greatest in D1 bone and is about 80% . D2, D3,D4 bone
have progressively decreasing percentage of bone at the
implant interface, with D4 bone ranging around 25%
interface contact at the initial healing and uncovering of a
titanium implant.

• D4 bone has the weakest biomechanical strength and
the lowest contact area to dissipate the load at the
implant to bone interface. Thus an improved functional
surface area per unit length of the implant is needed to
reduce the mechanical stress to this weak bone

• Depending on the bone density , the design , number,
length, diameter and type of the prosthesis should be
decided to optimize the biomechanical properties.

Length desirable
• D1 - 10mm
• D2 - 12mm
• D3 & D4 - 14mm with V shaped thread

width
• Increase in width – increase in surface area
• 1mm increase in width – 30% increase in surface area
• D3&D4 bone - wider implant

Implant number
• Increase in number – increases the functional loading
area
• Implant design
• Smooth cylindrical implant contribute shear force at
interface. Coating with titanium or hydroxy apatite
increases the implant surface area and there by
increases bone implant interface area

As density decreases , biomachanical load should
also decreased by :
• Shortened cantilever length
• Narrow occlusal table
• Offset load minimized
• RP4 prosthesis – removal at night
• RP5 prosthesis – force shared by the soft tissue
• Force directed along the long axis of implant

Treatment plans related to Key implant
positions and implant number
• Misch suggested 4 guidelines for key implant position
• No cantilevers
• No three adjacent pontic
• Canine – molar Rule
• Arch dynamics

No cantilevers
• Cantilevers on the prosthesis
should be reduced and
preferably eliminated ; there for
terminal abutments in the
prosthesis are key positions
• Cantilevers are force
magnifiers to the implant
• There for ideal key implant
positions include the terminal
abutment positions when
adjacent teeth are missing

No three adjacent pontic
• Three adjacent pontics
should not be designed in
the prosthesis
• All pontic span flux under
load
• The greater the span
between the abutments ,
greater the flexibility of
the metal in the
prosthesis

• Greater the flexure ,
greater the risk of
porcelain fracture ,
uncemented prosthesis,
and abutment screw
loosening
• One pontic span exhibit
little flexure -8micrometer
under 25 Ib load

• A two pontic span flexes
8 times mors than a one
pontic
• A three pontic span flexes
27 times more than a one
pontic span

• A five to seven unit fixed
prosthesis has three key
positions for the abutment .
The terminal abutment follows
the rule 1 (no cantilever). And
a one pier abutment is
positioned following
rule2.(nothree adjacent pontic).
Rarely are these three
abutment sufficient to support
the prosthesis in long term.
Additional abutments are
required when force factors are
moderate to severe or bone
density is poor around the
implant

Canine – molar rule
• Canine and first molar
sites are key positions
for implant placement,
especially when adjacent
teeth are missing

Key implant positions
• 3- 4 units - terminal
abutment
• 5 - 14 units - terminal
abutments
limit to two pontics

• If there is missing second
premolar , first molar and
second molar , three implant
positions are needed to restore
the full contour of the missing
molar teeth , the second
premolar and second molar
terminal abutments and the
first molar pier abutment

Arch dynamics
• An arch is divided into five
segments. When more than
one segment of an arch is
being replaced , a key implant
position is atleast one implant
in each segment
• Two centrals and two lateral
incisors are one segment ,
canines are independent
segment, and the premolars
and molars on each side form
a segment

Implant number
• The number of implant is
determined by the mesiodistal
dimension of the edentulous
arch
• When four adjacent teeth are
missing from the canine to first
molar, the two terminal key
implant positions are usually
inadequate to support the
prosthesis. One or two
additional implants are
required in most clinical
situations. The additional
implant of choice is the second
premolar site

• When six or more implants are
positioned in the mandible, a
cantilever may be designed in
the mandible because of
dynamics of the arch , with four
of the five sections of an open
pentagon joined , the large
anteroposterior distance , and
the favorable mandibular bone
density

• When seven or more implants
are placed in an edentulous
mandible , two separate
prosthesis with no posterior
cantilever may be designed
• Mandible flexure is free to
occur when the seperation
between the two prosthesis is
between the mental foraminae

• The ideal seven implant
positioning for a maxillary
edentulous arch includes at
least one central incisor
position , bilateral canine
position , bilateral second
premolar site and bilateral site
in the distal half of the first
molar . In case of heavy stress
factors , an additional anterior
implant and bilateral second
molar positions (to increase
the anteroposterior distance)
may be of benefit

Implant size
• An excessive implant length is not critical at the crestal bone
interface, but rather for initial stability and overall amount of bone
implant interface.
• The increased length also provide resistance to torque or shear
force when abutments are screwed into place
• However excessive implant length is not an effective method to
decrease stress from force factors
• Ideally softer bone type require longer implants than denser bone
• The surface area of each implant is directly related to the width of
the implant.
• Wider root form implant has a greater area of bone contact than
narrow implant

• 0.25 mm increase in implant diameter may increase the
overall surface area approximately 5% -10% in implant
body
• It has been suggested that an increase in implant
diameter is more effective than implant staggering to
reduce stress
• Ideal implant size is 12mm in length and >4mm in
diameter

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
endosteal implants is in part related to the
density of bone.
• The minimum bone height for predictable
long term Endosteal 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. Nasal floor
C. Maxillary sinus
D. Tuberosity
E. Mandibular canine region
F. Anterior mandible
G. Bone above the inferior mandibular canal

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 than 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
available bone in an
edentulous area is often
limited by adjacent teeth or
implants.
• For a bone more than 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 bone 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.

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.

Implant design
• Implant macrodesign may affect surface are even more
than an increase in width.
• A threaded implant provide 30% more surface area than
a cylinder implant
• Functional surface area increases by increasing the
depth of the thread
• There for implant design may be the easiest method to
increase surface area significantly and decrease overall
risk to the implant interface

References
• Contemporary Implant dentistry - Carl E Misch
• Text book of Oral Medicine - Anil Govindrao Ghom
• Implant Dentistry - Hobo

Diagnosis and treatment planning in implant dentistry

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