Tooth Loss and Prosthetic
Appliances
REF: Prosthodontics. Principles and Management Strategies.1996, Owall, Kayser and
Carlsson, Chap. 3, pp. 35-47.
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Tooth – type and function
Aesthetic units
Occlusal units
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Functional classification of the 28 teeth or
14 pairs of antagonistic units
Location
Name
Anterior area
Aesthetic units 6
Premolar area
Occlusal units
4
Molar area
Occlusal units
4 (81)
Total
Functional
units
14 (181)
1
in premolar equivalents.
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Number
Healthy or Physiological Occlusion

Absence of pathologic manifestations

Satisfactory function

Variability in form and function

Adaptive capacity
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Functional assessment of the different
tooth types
Function
Biting
Chewing
Speech
Aesthetics
Stability of:
TMJ
Dental arch
Anteriors
+
+
+
Premolars
+
+
Molars
+
±
+
+
+
+
+
+
+ = Prime involvement; - = No, or secondary involvement.
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(Stuart and Stallard,1960)
Can anterior teeth and premolars
compensate for the function of
the molars?
(shortened dental arch)
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Schematic representation of the aetiology of an impaired dentition
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Natural history of the dentition in
high-risk groups
Healthy dentition
Minor changes (intact occlusion)
Major changes (impaired occlusion)
Edentulousness (lost occlusion)
Loss of alveolar bone
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Biological and functional
aspect of tooth loss
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Changes following tooth loss
Adaptation
or
Pathological condition
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Spontaneous closure of open space in a 32-year-old man after loss of tooth
11 at the age of 12 years due to trauma
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Effects of tooth loss on the remaining dentition
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Radiographs of a 52-year-old woman (1992) showing structural and
functional stability of an extreme shortened dental arch (8 occluding
units) after 20 years (a) and 28 years of function (b).
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Local factors influence the consequences
of tooth loss

Location of the lost tooth

Number of the lost teeth

Intercuspation

Periodontal condition

Position of the tongue
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Systemic factors influence the
consequences of tooth loss

Age

Adaptive capacity

General resistance

Neuromuscular tolerance

Psychological condition
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Sequelae of tooth loss
Migration
Unilateral chewing
Alveolar bone loss
Occlusal interference
Loss of proximal contact
Overloading of anteriors
Loss of VD
TMD
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General Pattern of Tooth Loss
Molars then premolars.
Lastly the lower anteriors.
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(a)
(b)
Possible migration after loss of tooth 36
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(a)
(b)
(a) A new occlusal balance was established after loss of teeth 46 and
47 at the age of 22 years in a 28-year-old woman (1971), followed
during 11 years. (b) alveolar
bone height in 1971 and 1984.
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Loss in the anterior region

Disturbed aesthetics

Disturbed speech

Affected psychosocial function
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Patterns in partial edentulism
1.
Eichners classification (no. of remaining
occlusal supporting zones)
2.
Simple classification of impaired dentitions
•
•
3.
Uncomplicated
Complicated
Partial edentulism
•
•
Tooth boundspace
Shortened dental arch
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The Eichner Index, based on supporting zones of antagonist contacts
in premolar and molar regions (Helldén et al., 1989)
A1
A2
A3
B1
B2
B3
C1
C2
C3
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B4
Uncomplicated tooth-bound space in
the left mandible
Complicated tooth-bound space,
showing migration of remaining teeth
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Uncomplicated shortened dental arch
Complicated shortened dental arch:
migration of remaining teeth, loss of
vertical dimension and dislocation of
condyle
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Compensation of tooth loss

Chewing where most occlusal contact

More chewing strokes

Swallowing of larger particles
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Migration in tooth bound spaces

Distally located teeth drift and tip mesially

Mesially located teeth drift and tip distally

Extrusion with no opposing contact
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Migration
Premature contact and interferences
Adaptation
Pathological condition (TMD)
(close in new position)
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Shortened dental arches
Premolar dental arch
Extreme shortened dental arch
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Complicated shortened dental arch: migration of remaining teeth,
loss of vertical dimension and dislocation of condyle
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Masticatory function measuring
Objectively
Chewing test
(masticatory performance)
Subjectively
Questionnaire or interview
(masticatory)
MP (no. of occlusal units ability)
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10 occluding pairs
will be sufficient
Schematic representation of the relationship between masticatory
function and dental arch length (expressed in occlusal units)
1 = Masticatory ability (perceived
ease of chewing)
2 = Masticatory performance
A = Area of sufficient masticatory
function
B = Turning range
C = Area of insufficient
masticatory function
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Stability of premolar dental arch

Occlusal contact in IP

Overbite

Interdental spacing

Attrition and alveolar bone support
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Effect of periodontal problems
on shortened dental arches
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Oral comfort

Absence of pain

Satisfactory masticatory ability

Acceptable aesthetics
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Relationship between oral function and shortened dental arches
1 = Contact between anterior teeth in
IP
2 = Alveolar bone height
3 = Interdental contact between
anterior teeth; absence of
mandibular dysfunction
4 = Chewing capacity
5 = Aesthetics
A = Area of sufficient and function
(adaptation)
B = Turning range
C = Area of insufficient oral function
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Dental arch support and TMJ
Posterior tooth loss
TMJ osteoarthrosis
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Implications for prosthetic treatment
28 tooth syndrome
Over treatment
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Dental Care Aim
To maintain a healthy natural
functioning dentition for life
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“The exact number of teeth each individual need,
can not be ascertained by the dental profession.”
“If patient manage well with any number of teeth,
then there is no reason to recommend prosthetic
appliances.”
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Oral Function Level
Optimal
Sub-optimal
Minimal
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Required oral functional level in relation to age,
expressed as the minimum number of occluding
pairs of teeth (arch length)1
Age (years)
Functional level
Occluding pairs
20 – 50
I: Optimal
12
40 – 80
II: Suboptimal
10 (SDA)
70 – 100
III: Minimal
8 (ESDA)
1
SDA = Shortened dental arch; EDSA = Extreme shortened dental arch
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The Shortened Dental
Arch Concept
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I = Complete dental arch (optimal
function)
II = Shortened dental arch
(suboptimal function)
III = Extreme shortened dental
arch (minimal function)
A = High-risk factors (caries,
pockets)
B = Limiting factors (restricted
finances)
C = Patient factors (poor general
health)
The occlusal preservation target in high-risk groups
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The prosthetic treatment target in high risk groups. The number of
teeth to be restored is dictated by the needed functional level.
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Teeth should be replaced for

Aesthetics

Functional comfort

Occlusal stability
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Lecture No.2
Pre-edentulism
Ref: Prosthodontics. Principles and Management Strategies. 1996, Owall, Kayser
and Carlsson, Chap. 4, pp. 49-47.
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Natural history of the dentition in
high-risk groups
Healthy dentition
Minor changes (intact occlusion)
Major changes (impaired occlusion)
Edentulousness (lost occlusion)
Loss of alveolar bone
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The traditional restorative approach in prosthetic dentistry
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Pre-edentulous situation

Just a few (non-strategic) teeth are left with poor
prognosis.

The distribution of the remaining teeth in the
dental arches is often unfavorable  oral function
cannot be performed adequately.
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Preventive prosthetic treatment
for the pre-edentulous patient
Postponing of tooth extraction to
prevent bone loss
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Principles of preventive prosthetic treatment
for the pre-edentulous patient

Treatment planning and timing of tooth extraction

Shortening the dental arch with preservation of
occluding pairs of teeth

Use of an overdenture
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Treatment planning and timing of tooth
extraction

Condition of residual tooth

Age
 Postponement
of extraction delays the reduction of the
alveolar ridge
 Extraction
of teeth with severe periodontitis (targeted
extraction)  less bone resorption
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Shortening the dental arch with preservation of
occluding pairs of teeth

Free-end RPD X shortened dental arch

If no remaining occluding pairs  the remaining
teeth will cause damage to opposing edentulous
jaw

Preventive implantology
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Due to the removal of the antagonistic tooth in the mandible, the
solitary maxillary tooth has caused bone loss in the mandible
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(a) An example of a patient with a dental situation
with no occluding pairs of teeth (natural
versus artificial teeth) and severe alveolar bone
resorption of the edentulous maxilla.
(b) The teeth in the mandible are functionally
“locked”. Every movement of the jaw causes
the lower teeth to damage the edentulous
maxilla via the upper denture.
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A dentate maxilla opposing an edentulous mandible should always be avoided. A
situation of natural teeth versus artificial teeth has led to severe alveolar bone loss of
the mandible
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Use of an (immediate)
overdenture
Preservation of the alveolar ridge
Preserving lower canines
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(a) Orthopantomogram of a 45-year-old female
patient (1987) with an edentulous maxilla and
periodontal disease in the mandible. In spite
of the poor periodontal condition, it was
decided to make a complete immediate
overdenture in the lower jaw, while retaining
four abutment teeth.
(b) The situation 6 years after treatment (1993).
Good oral hygiene and plaque control using
chlorhexidine (Hibigel®).
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Schematic summary of the treatment planning by a pre-edentulous
patient with a residual mutilated dentition
- motivation, instruction
- treatment of periodontium
and caries
- “targeted” extractions
- removable partial
(immediate) denture
- recall
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(a) In a 61-year-old woman with poor oral hygiene,
a complete immediate overdenture, while
retaining both lower canines, was inserted in
1986.
(b) In the clinical situation more than 7 years later
(1993), oral hygiene is good, resulting in a
healthy periodontium and hardly any alveolar
bone loss.
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Assessment of the pre-edentulous dentition for
overdentulous treatment

Caries

Periodontal considerations

Prosthetic consideration
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Caries
Extensive and active caries
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Periodontal consideration

Mobility

Type of bone loss

Extraction, subgingival curettage
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Endodontic Consideration

Single rooted canal and apical radiolucency

Successful endo treated tooth
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Prosthetic Considerations
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If the vertical jaw relationship shows sufficient denture space,
abutment teeth which are (more or less) opposing should be retained
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Prosthetic considerations in the selection of abutment teeth
If possible always
If opposing teeth are
present in the mandible
in order to avoid “natural
vs artificial teeth”
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Location of the abutment teeth
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The division of the jaw into four zones to facilitate the selection of
abutment teeth
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Examples of the distribution of abutment teeth within the dental arch
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Canines as an overdenture abutments

Longest teeth

Strategic position

Oval-shaped root

Easy endo treatment
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(b) In the clinical situation more than 7 years later (1993), oral hygiene is
good, resulting in a healthy periodontium and hardly any alveolar bone
loss.
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Distribution of abutment teeth over the
upper and lower jaw

Situations in which teeth oppose an
edentulous part of the jaw should be
avoided.
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Many pre-edentulous situations between the lower and upper jaw are undesirable
from a prosthetic point of view (green in illustration). The figure indicates which
dental situations offer a good starting point for making an overdenture.
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A “targeted extraction strategy”, possibly combined with the making of an
overdenture, enables the balance of forces between the dental arches to be restored.
(NB The use of dental implants makes other combinations possible)
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Dental implants as abutment teeth for
overdentures
(a) The use of implants in the lower jaw restores
the balance between the dental arches.
(b) Reduction of tooth material in the lower jaw
can be avoided by inserting implants in the
upper jaw.
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The main goal in “preventive prosthodontics” is the preservation of oral function for
life. Dental implants can effectively “reverse” complete edentulousness and restore
oral function
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Submerged roots and submucosal
implants

Root of fractured teeth

Filling the socket with biocompatible material
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Orthopantomogram of a patient with submucosal implants (calcium
hydroxyapatite), inserted immediately after extraction.
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Depending on the individual rate of resorption, the upper surface of the
submucosal implants will sooner or later protrude above the level of the
jawbone with dehiscence of the mucosa.
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