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 unitsLocation Name Number

Anterior area

Aesthetic units

6

Premolar area

Occlusal units

4

Molar areaOcclusal units

4 (81)

TotalFunctional units

14 (181)1 in premolar equivalents.

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Healthy or Physiological Occlusion

Absence of pathologic manifestations

Satisfactory function

Variability in form and function

Adaptive capacitySamar Al Saleh

Functional assessment of the different tooth typesFunction Anterior

sPremolars

Molars

Biting + - -Chewing - + +Speech + - -Aesthetics + + ±Stability of: TMJ + + + Dental arch

+ + ++ = Prime involvement; - = No, or secondary involvement. (Stuart and Stallard,1960)

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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

Loss of alveolar bone

Edentulousness (lost occlusion)

Major changes (impaired occlusion)

Minor changes (intact occlusion)

Healthy dentition

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Biological and functional aspect of

tooth loss

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Changes following tooth loss

Adaptationor

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

MigrationUnilateral chewing

Alveolar bone lossOcclusal interference

Loss of proximal contactOverloading of

anteriorsLoss of VD

TMDSamar Al Saleh

General Pattern of Tooth Loss

Molars then premolars. Lastly the lower anteriors.

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Possible migration after loss of tooth 36

(a) (b)

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(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.

(a) (b)

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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• Uncomplicated• Complicated

3. 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

B4

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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 condyleSamar Al Saleh

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

ObjectivelyChewing test

(masticatory performance)

MP (no. of occlusal units ability)

SubjectivelyQuestionnaire or interview

(masticatory)

10 occluding pairswill be sufficient

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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 rangeC = 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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1 = Contact between anterior teeth in IP

2 = Alveolar bone height3 = Interdental contact

between anterior teeth; absence of mandibular dysfunction

4 = Chewing capacity5 = Aesthetics

A = Area of sufficient and function (adaptation)

B = Turning rangeC = Area of insufficient oral

function

Relationship between oral function and shortened dental arches

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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

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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

Loss of alveolar bone

Edentulousness (lost occlusion)

Major changes (impaired occlusion)

Minor changes (intact occlusion)

Healthy dentition

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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 opposing teeth are present in the mandible in order to avoid “natural vs artificial teeth”

If possible always

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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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(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.

Dental implants as abutment teeth for overdentures

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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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