Changing concepts of attritional occlusion (3)

Changing concepts of attritional
occlusion
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 Oldness of the idea regarding Attritional
occlusion.
 Stone age man’s dentition
 Characteristics of Attritional occlusion
 Correlative studies
 Relevance of Begg’s hypothesis to the
present day
 Present view regarding Attritional occlusion.

Oldness of the idea of attritional
occlusion.
 Sim Wallace (1904)
1. Introduced the “disuse” idea.
2. Correlated growth of U/L jaws
3. Teeth – exact and definite
4. Importance of chewing
5. Unnecessary blame on heredity
6. Brain vs. osseous structures

Cambell T.D. (1925)
 Compared the quality and methods of
preparation of food b/w native and present
day aboriginals.
 Crude methods of preparation of food
required a very vigorous masticatory effort
which led to a very efficient and perfect
dentition.
 Dental diseases limited to individuals of
advanced years due to refinements in food.

Klatsky and fisher (1953)
 Reintroduced the idea of SimWallace.
 Malocclusion – Disease of civilization.
 Re-examined 3 basic factors :
1. Heredity -- x
2. Environment -- x
3. Function -- √
 Undue importance on nutritional aspects of
diet rather than on food texture.

Stone age mans dentition
Dr.P.R.Begg
 Termed as Attritional occlusion
 Concept based on studies on Australian
aboriginals.
 Their teeth exhibited :
1. Extensive occlusal and interproximal wear.
2. Lack of caries, pdl disease, crowding.
 He considered the above as normal and
civilised man’s unworn dentition and
related problems as abnormal.

Anatomically correct occlusion
 Correct occlusion – Based on continual
change.
 2 important factors :
 Position of teeth in jaw bones.
- continual mesial migration and
vertical eruption which compensate for
tooth attrition.
 Anatomy of teeth.
- changing anatomy, dependent
upon attrition.

Stone age mans dentition
 When stone age man’s decidous incisors
erupt, his hard, coarse, fibrous, gritty food
immediately commences the process of
interproximal reduction and occlusal
attrition.
 Prerequisite – excess of tooth substance.
 As attrition occurs upper and lower
decidous incisors assume an edge to edge
overbite

 Decrease in the overall M-D length of the
deciduous dental arches.
 i.e. the permanent molars erupt further
mesially in the jaws than in civilized man.
 Begg’s view on Angle’s classification.

 As the permanent teeth erupt the process
of attrition is continous.
 Permanent incisors erupt in an overbite
similar to that of civilised man but soon
assume an edge to edge bite.
 i.e. lower incisors
- more prominent.
- curve of spee flat mesiodistally.

 Also , during the transition to an edge to
edge bite :
-- canines, premolars and 2nd
molars wear
interproximally and occlusally but maintain
contact by mesial migration.
-- provides adequate space for erupting
canines, 2nd
molars and 3rd
molars.

Begg (1930)
 Aim:
To evaluate the amount of reduction in size
of the lower dental arch prior to the
eruption of lower 3rd
molars.
 Measurements done on aboriginal skulls
collected from the south australian museum
using a boley guage in millimeters.
 Mandibles separated into 2 sets.

Results
 Difference b/w the 2 sets of measurements
-- 5.28 mm x 2 = 10.56 mm
 Maxilla : 1mm less than mandible.
 The above figure according to Begg is an
underestimation as canines, PM’s and 2nd
molars have just erupted
 with aid of “restoration” pencil drawing the
estimated reduction in arch width –14.7mm

Four degrees of tooth wear (Broca)
 First stage : enamel worn without
exposure of dentin
 Second stage : cusps worn down
and dentine exposed
 Third stage : appreciable amount of
crown worn away
 Fourth stage : wear extended to the
neck of the tooth

 Disagrees with :
-- Strang, Huckaba
-- Anthropologists
-- G.V.Black, E.H.Angle and others
 Concludes that textbook normal occlusion
develops only in those individuals who have
too small an amount of tooth substance.

Characteristics of attritional occlusion
( Evidence in favour of attritional occlusion )
 Edge to edge anterior overbite
 Gingival recession and vertical eruption
 Caries and periodontal disease
 Eruption of first permanent molars
 Anatomy of TMJ
 Proximal wear
 Eruption of 3rd molars
 Change in the curve of Wilson
 Reason for Cusps of Carabelli
 Secondary dentin and Pulpal pain
 Low incidence of malocclusions with tooth
crowding.

Edge to edge anterior overbite

Gingival recession and vertical eruption

Caries and periodontal disease

Eruption of first permanent molars

Anatomy of TMJ
 Shallow glenoid
fossa
 Low eminentia
articularis
 Flattened condylar
head
 Deep fossa
 Round condylar
head

Proximal wear

Eruption of 3rd molars

Change in the curve of Wilson
+ Reason for Cusps of Carabelli

Secondary dentin and Pulpal pain

Variation of clinical procedures based
on the tenents of attritional occlusion
 Extractions are rational based on a sound
etiological basis as it simulates the
extensive M-D attrition in SAM.
 If tooth material excess is mild Ist PM
extraction suffices and if its grossly excess
8 teeth extractions are needed
 Opening of the bite to edge to edge position
in stage 1
 Retraction of upper incisors to edge to edge
position in stage 1
 Mesial movement of posterior teeth in
general in stage 2.

Evaluation of Australian aboriginals
(Corrucini et.al)
 Aim: To evaluate the Begg hypothesis.
 Method :A collection of dental casts from
the Yuendumu settlement situated 285km
northwest of Alice Springs in the northern
territory of Australia.
 Established in 1946 to provide a central
area for provisioning aboriginals who had
left their tribal areas

 Study consisted of 4 groups :
1. Older generation – born before 1937 (48)
2. Younger generation – post 1937 (48)
3. Aboriginal skulls – south aus.museum (48)
4. Haasts Bluff cast collection (35)

 Each occlusal variable was statistically
evaluated.
 The younger vs. older contrast was given
primary interest as it explained the effect of
civilization.

Results

Examination of dental crowding and its
relationship to tooth size and arch dimension
 Howe , Mcnamara
 To examine the extent to which tooth size
and jaw size contribute dental crowding.
 Conditions predispose crowding:
1. Excessively large teeth
2. Small bases
3. Combination

Materials and methods
 104 subjects – maxillary and mandibular
casts
 2 groups:
-- Non-crowded group
-- Crowded group
 Measurements :
- M-D tooth diameters
- Arch width
- Arch perimeter

 Conclusion
-- subjects with dental crowding were
more likely to have smaller dental arch
measurement than subjects without
crowding
-- treatment could be directed towards
1. Reduction of tooth mass
2. Dental arch expansion
3. Combination of both

Reassesment of Begg’s study
 2 studies done by Dawes, at university of
Adelaide in 1987 and other by Corrucini in
1990 showed a greater variance with the
results obtained by Begg.
 Studies on Attritional occlusion similar to
begg have not been able to relate with the
value of 10.56mm. Their estimate ranged
from 20-40% of begg’s value.
-- Fishman 1976
-- Murphy, Beyron 1964
-- Dawes 1987
-- Kaul 1990www.indiandentalacademy.com

 Dawes points a discrepancyb/w the
measurements of Cambell and Begg.If begg
were to use cambells measurements the
value would have been 7.24 instead of
10.56.
 His measurements on skulls with and
without attrition were identical.
 Major evidence against Begg’s Hypothesis
was the longitudinal study on Yuendumu
aboriginals. Results were in contrast to the
cross-sectional approach of Begg.

 Summarized findings of Yuendumu study:
- No occluso-incisal attrition observed in
Yuendumu subjects.
- Leeway space could not be co-related to
crowding
- The overall size of teeth did not correlate to
crowding as the size of teeth of normal and
malocclusion subjects being identical.

Relevance of attritional occlusion to the present day
 Attrition does occur in SAM perhaps less
than 10.56mm
 The role of diet, attrition and mesio-occlusal
migration are biologically valid explanations
in accounting for malocclusion
 Mesio occlusal migration in modern man is
predicted on good tooth contacts and when
a loss of tooth occurs the teeth distal to the
site of loss move mesially.
 Extractions undertaken significantly
improve esthetics and long-term stability.

References:

Changing concepts of attritional occlusion (3)

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