attritional occlusion - ortho / orthodontic courses by indian dental academy

ATTRITIONAL OCCLUSION

INDIAN DENTAL ACADEMYLeader in continuing dental education

www.indiandentalacademy.com


Definitions

AttritionAttrition:: It’s a process in which tooth tissue is It’s a process in which tooth tissue is

removed as a result of opposing tooth surfaces removed as a result of opposing tooth surfaces contacting during function or para function. contacting during function or para function. Such direct contact occurs at proximal areas, Such direct contact occurs at proximal areas, on supporting cusps and on guiding surfaces on supporting cusps and on guiding surfaces during empty grinding movements.during empty grinding movements.


Attritional Occlusion:

It is an occlusion which is continually changing through out the life and are caused mainly by the tooth migration and changing anatomy of teeth, due to the physiological process of attrition.


Different stages of occlusal attrition seen in Australian Aboriginal Dentition are shown in the figures.


IntroductionThe objective of orthodontic treatment is to correct The objective of orthodontic treatment is to correct malocclusion of the teeth and those deformities of the malocclusion of the teeth and those deformities of the jaw and face associated with it.jaw and face associated with it.Modern era of dentistry always accepted “textbook Modern era of dentistry always accepted “textbook normal” occlusion as anatomically and functionally normal” occlusion as anatomically and functionally correct occlusion.correct occlusion.Presence of deformities and orthodontic treatment Presence of deformities and orthodontic treatment needs are determined with the “textbook normal” needs are determined with the “textbook normal” occlusion in mind.occlusion in mind.The concept of “Attritional Occlusion” was introduced The concept of “Attritional Occlusion” was introduced by the Australian Dr P.R.Begg after intense studies of by the Australian Dr P.R.Begg after intense studies of dentitions in Australian Aboriginal skulls. dentitions in Australian Aboriginal skulls.


Broca’s Classification of AttritionFirst stage-enamel worn without cusp obliteration or exposure of dentine.

Second stage-cusps worn down and dentine exposed.

Third stage-appreciable amount of the crown of the tooth is worn away.

Fourth stage-extreme stage where most of the crown has disappeared and the wear has extended to the neck of the tooth.


As a boy he saw the skulls of Australian Aboriginals, and noticed that their teeth were worn flat. This motivated him to study these skulls later and came up with the concept of “Attritional Occlusion”.

Attritional Occlusion was mainly observed in stone age man and Begg used Australian Aboriginals as a model for stone age man.

The teeth of these skulls had extensive occlusal and inter proximal wear. The most astonishing fact was that crowding and malocclusion was almost absent in these skulls.

Dr Begg was the first to appreciate the fact that the teeth are ever on the move.

Begg’s Hypothesis


All these time he was following the “Non Extraction Technique” advocated by Dr Angle.

But he was not satisfied with the post treatment results he obtained.

In 1954, Begg reasoned that the relatively low incidence of malocclusion in stone age man is due to the reduction by more than half an inch in the total length of each of these dental arches.

This was caused by tooth attrition so that the smaller crowns (in mesio distal diameter) could be more easily accommodated into the jaws.

So he advised extractions and proximal stripping in patients with excess tooth substance so as to attain a correct occlusion. www.indiandentalacademy.com

Thus he stated that the “Textbook normal” Occlusion was itself a malocclusion and the stone age man’s “Attritional Occlusion” as the anatomically and functionally correct occlusion of the human race.

He advocated that this should be the basic concept on which to build the foundations for the development of the various branches of dental treatment, mainly in Orthodontics.


Adult Australian aboriginal dentition - described by Begg as anatomically correct attritional occlusion, including the edge-to-edge bite of the incisor teeth.


Two Factors in Correct Occlusion

Changing Anatomy of TeethChanging Anatomy of TeethAttrition plays an important part in the evolution of Attrition plays an important part in the evolution of the anatomy of the teeth, their growth processes, the anatomy of the teeth, their growth processes, function and characteristics, which confer freedom function and characteristics, which confer freedom from diseases of the teeth and their supporting tissues.from diseases of the teeth and their supporting tissues.This tooth wear chiefly takes place occlusally, incisally This tooth wear chiefly takes place occlusally, incisally and proximally.and proximally.According to the concept, continual loss of tooth According to the concept, continual loss of tooth substance by attrition is a normal functional process substance by attrition is a normal functional process and absence of this causes malocclusion.and absence of this causes malocclusion.However it has affected man’s esthetic sense so that he However it has affected man’s esthetic sense so that he now prefers the appearance of unworn teeth.now prefers the appearance of unworn teeth.


Attrition causes continual changes in the

shapes and sizes of the teeth


Tooth MigrationTeeth continually move throughout life in two directions simultaneously.

1. Horizontal (mesial migration).

2. Vertical (continual eruption).

This is caused mainly by the attrition.

Figure shows mesial migration and vertical eruption;move the teeth occlusomesially in the jaws.


Anatomically Correct OcclusionAnatomically correct occlusion can develop only when Anatomically correct occlusion can develop only when there is sufficient attrition of the teeth for them to assume there is sufficient attrition of the teeth for them to assume correct occlusial relationship.correct occlusial relationship.Stone age man’s teeth have occlusal and proximal Stone age man’s teeth have occlusal and proximal attrition.attrition.Often this is so marked that the dentine is exposed but are Often this is so marked that the dentine is exposed but are not subjected to dental caries.not subjected to dental caries.In civilized man, the occlusion is anatomically incorrect In civilized man, the occlusion is anatomically incorrect because his food is too soft and concentrated to cause because his food is too soft and concentrated to cause tooth attrition.tooth attrition.The incisal, occlusal, proximal and axial relations of The incisal, occlusal, proximal and axial relations of civilized man’s teeth remain almost static throughout life.civilized man’s teeth remain almost static throughout life.


Again civilized man’s jaws are prevented by unworn teeth from assuming correct relations to each other in all directions, especially the vertical.

In fact civilized man’s upper and lower jaws are forced farther apart as his teeth continually erupt without being continually reduced in vertical length by occlusal and incisal attrition.


Process of Attritional Occlusion in Stone Age Man

Australian Aborigines- the original inhabitants of the Australian Aborigines- the original inhabitants of the continent- were one of the best known but least under continent- were one of the best known but least under stood people in the world.stood people in the world.They have occupied Australia for atleast forty They have occupied Australia for atleast forty thousand years.thousand years.Although aborigines are Homo sapiens, biological Although aborigines are Homo sapiens, biological isolation has meant that they are not racially closely isolation has meant that they are not racially closely related to any other people.related to any other people.Since the nineteenth century, they have been singled Since the nineteenth century, they have been singled out as the most primitive culture and the living out as the most primitive culture and the living representatives of the ancestors of mankind.representatives of the ancestors of mankind.


They were mainly hunter gatherers.

Their food contained much more indigestible bulk and roughage than civilized man’s food.

He had to eat a larger quantity of food than we do in order to sustain himself.

Therefore extensive and rapid occlusal and proximal attrition developed throughout the life of their deciduous and permanent dentitionwww.indiandentalacademy.com

Attritional Occlusion in Deciduous DentitionDeciduous incisors erupt in overbite relation (primitive man & civilized man)

Incisal and occlusal wear---hard,coarse and gritty food.

Initially – oblique, later- horizontal relation of incisors

Lower incisors tip labially while upper incisors get

more upright until an edge to edge relationship is

obtained—seen in both deciduous,& permanent

dentition of stone age man. www.indiandentalacademy.com

Because of this edge to edge relationship and the continual attrition, the lower dentition is moving forward.

This forward movement of the occlusal relation of stone age man’s lower deciduous dental arch, related to the upper, causes distal surfaces of the lower second deciduous molar to assume positions farther mesially than the distal surfaces of upper deciduous second molar.


In civilized man

Persistence of the anterior overbite

Lower incisors locked in a functionally

and anatomically incorrect position

Lower incisors restrained from proclining

Crowding of teethwww.indiandentalacademy.com

Mixed Dentition- Eruption of Permanent Teeth

Occlusal Attrition causes the occluso-cervical heights of Occlusal Attrition causes the occluso-cervical heights of all stone age man’s deciduous teeth to be reduced.all stone age man’s deciduous teeth to be reduced.

Therefore stone age man’s upper and lower first Therefore stone age man’s upper and lower first permanent molars have less distance to erupt before permanent molars have less distance to erupt before occluding with each other.occluding with each other.

Because of extensive proximal attrition of the Because of extensive proximal attrition of the deciduous teeth, the over all mesio – distal lengths of deciduous teeth, the over all mesio – distal lengths of the upper and lower deciduous dental arches are the upper and lower deciduous dental arches are considerably reduced.considerably reduced.


Due to this, the second deciduous molars migrate so far Due to this, the second deciduous molars migrate so far mesially that stone age man’s first permanent molars erupt in mesially that stone age man’s first permanent molars erupt in a much farther mesial position.a much farther mesial position.


In contrary, the distance between the upper and lower jaws of civilized man is much more compared to that of stone age man.

As a result the upper and lower first permanent molars have greater distance to erupt before occluding with each other.

Also persistent anterior overbite causes initial end to end molar occlusion in civilized man.


In Angle’s classification of malocclusion diagnosis is claimed to be aided by observing the occlusal relation of the first permanent molars.

Whereas according to the attritional occlusional concept the unqualified use of the first permanent molars as diagnostic landmarks in angle’s Classification is misleading.

Since in civilized man there is absence of proximal and occlusal attrition in deciduous dentition, it prevents the continual mesial migration of the first permanent molars that must necessarily occur for the development of anatomically and physiologically correct occlusion.


Shallow Glenoid Fossa and Flat Head of Mandibular Condyle

During the period of development of stone age man’s During the period of development of stone age man’s deciduous dentition, the glenoid fossa is shallow and deciduous dentition, the glenoid fossa is shallow and the head of the condyle is relatively flat.the head of the condyle is relatively flat.Therefore, lateral mandibular movements during Therefore, lateral mandibular movements during mastication are extensive and wide.mastication are extensive and wide.Civilized man’s condylar head is smaller and more Civilized man’s condylar head is smaller and more rounded and it fits up farther into the glenoid fossa so rounded and it fits up farther into the glenoid fossa so that the range of mandibular masticatory excursions is that the range of mandibular masticatory excursions is more restricted. more restricted.


The absence of attrition of deciduous teeth in civilized man creates conditions that prevent development of proper occlusion of permanent teeth resulting in crowding,overlapping and bimaxillary protrusion.

In developing attritional dentition, each tooth of the second set after it erupts comes into occlusion and immediately begins to wear both occlusally and proximally. So when the next teeth erupts, the previous one is already worn considerably.


Attritional Occlusion in Permanent Teeth

With the establishment of the edge to With the establishment of the edge to edge permanent incisor bite due to edge permanent incisor bite due to attrition, the stone age man’s “Curve of attrition, the stone age man’s “Curve of Spee” is not so curved as in “textbook Spee” is not so curved as in “textbook normal” occlusion.normal” occlusion.It is usually almost a flat plane mesio-It is usually almost a flat plane mesio-distally.distally.


MODERN MAN-The anterior overjet and the acute angle formed by the incisors.

STONE AGE MAN-Observe the reduced overjet and the more upright inclination of the incisor teeth.


In the absence of attrition, there is not enough space for the canine to erupt as in civilized man.

Attrition brings about enough reduction in mesio-distal Attrition brings about enough reduction in mesio-distal dimensions of teeth to allow adequate space for the erupting dimensions of teeth to allow adequate space for the erupting permanent canine.permanent canine.


During this stage of development of stone age man’s dentition, all the erupted teeth undergo the process of attrition.

This early attritional reduction in the overall lengths of the dental arches prevents the development of crowding, overlapping, rotation and bimaxillary protrusion of the six upper and lower permanent anterior teeth, as well as irregularities and crowding of the premolars, all of which would inevitably occur in the absence of attrition.

Again, this attritional reduction in the lengths of the dental arches leaves more space at the distal ends of the dental arches for the eruption of the third permanent molars.


Eruption of Third Permanent Molars

As all teeth erupt several years before their root formation As all teeth erupt several years before their root formation is completed, stone age man’s third permanent molars is completed, stone age man’s third permanent molars obey this rule by erupting in their correct positions in the obey this rule by erupting in their correct positions in the jaws much farther mesially than they are able to erupt in jaws much farther mesially than they are able to erupt in civilized man.civilized man.Where as the civilized man’s unerupted third permanent Where as the civilized man’s unerupted third permanent molars are held too far distally in the jaws causing molars are held too far distally in the jaws causing impactions. Also they are the only teeth that have their impactions. Also they are the only teeth that have their root formation completed before eruption.root formation completed before eruption.By calculations, it was estimated that there was 14.7mm By calculations, it was estimated that there was 14.7mm attritional dental arch reduction in the mandible of stone attritional dental arch reduction in the mandible of stone age man for providing enough space for third molar age man for providing enough space for third molar eruption.eruption.


Super imposition of attritional over non -attritional occlusion is shown in the above figure to illustrate the amount of space left by attrition and mesial migration for earlier eruption of third permanent molars.


•The recent secular trend in increasing impactions does not seem to be a genetic change in humans. Instead, it is merely a response to a soft food diet.

•Without interproximal wear of the teeth, there simply is not enough room for third molar.

•Other factors at work with modern soft diets is dental arch width: narrower dental arches that result from disuse also contribute to shorter dental arches with less space available distal to second molars.


Advanced Attrition In Stone Age Man.

In some Aboriginal skulls, occlusal attrition of the first In some Aboriginal skulls, occlusal attrition of the first permanent molars has extended so far that the crowns permanent molars has extended so far that the crowns of these teeth have worn away completely and attrition of these teeth have worn away completely and attrition has extended down the roots, beyond the level of has extended down the roots, beyond the level of bifurcation of these roots.bifurcation of these roots.

It is not strictly correct to state that the process of It is not strictly correct to state that the process of continual tooth eruption evolved to compensate for the continual tooth eruption evolved to compensate for the tooth attrition specifically. tooth attrition specifically.

It is only a particularization of the much more It is only a particularization of the much more primitive and general process of continual outward primitive and general process of continual outward growth of all surface epithelial structures. growth of all surface epithelial structures.


Vertical And Mesial Eruption

The maintenance of proximal tooth contact, as The maintenance of proximal tooth contact, as proximal attrition proceeded was made proximal attrition proceeded was made possible by mesial migration of the teeth.possible by mesial migration of the teeth.

The occlusion is also maintained by the The occlusion is also maintained by the continual vertical eruption of teeth.continual vertical eruption of teeth.

In short the both vertical and horizontal In short the both vertical and horizontal eruption of the teeth simultaneously results in eruption of the teeth simultaneously results in the gross movement of the teeth obliquely. the gross movement of the teeth obliquely.


Effects of Attrition on The Evolution of Human Teeth

The evolutionary development, both of the The evolutionary development, both of the individual teeth and of anatomically correct individual teeth and of anatomically correct attritional occlusion is dependent on continual attritional occlusion is dependent on continual tooth attrition.tooth attrition.

Following are some of the important effectsFollowing are some of the important effects


Deposition of Secondary Dentin

The process of deposition of secondary dentin by the The process of deposition of secondary dentin by the tooth pulp evolved to prevent the exposure of the pulp tooth pulp evolved to prevent the exposure of the pulp by attrition.by attrition.This process did not evolve to wall of dental caries from This process did not evolve to wall of dental caries from exposing the tooth pulp, because dental caries was exposing the tooth pulp, because dental caries was almost non existent in stone age man.almost non existent in stone age man.Secondary dentin is continually laid down in civilized Secondary dentin is continually laid down in civilized man’s teeth, even when there is no attrition or dental man’s teeth, even when there is no attrition or dental caries, so that, in old age the pulp chamber is often caries, so that, in old age the pulp chamber is often almost obliterated.almost obliterated.


Continual Vertical Tooth Eruption

B. Gottlieb have been the first to draw B. Gottlieb have been the first to draw attention to this process in man.attention to this process in man.

P. R. Begg in 1938 showed that the process of P. R. Begg in 1938 showed that the process of continual eruption and mesial migration continual eruption and mesial migration evolved to compensate for tooth attrition.evolved to compensate for tooth attrition.


Continual Mesial Migration of The Teeth

This process is evolved to preserve the This process is evolved to preserve the continuity of the dental arches by proximal continuity of the dental arches by proximal contact of the teeth as they continually wore contact of the teeth as they continually wore away on their proximal surfaces.away on their proximal surfaces.

Mesial migration prevents the development of Mesial migration prevents the development of tooth spacing, which detracts from the tooth spacing, which detracts from the masticatory efficiency of the dental apparatus.masticatory efficiency of the dental apparatus.


Large Mesio-Distal Diameters of Unworn Deciduous Molars

If the mesio-distal diameters of stone age man’s If the mesio-distal diameters of stone age man’s unworn deciduous molars were not greater unworn deciduous molars were not greater than the corresponding diameters of the than the corresponding diameters of the premolars which succeed them, attrition, premolars which succeed them, attrition, coupled with mesial migration, would have coupled with mesial migration, would have made the diameters of the deciduous molars so made the diameters of the deciduous molars so small that there would not have been sufficient small that there would not have been sufficient mesio-distal space for the eruption of the mesio-distal space for the eruption of the premolars.premolars.


Shapes and Forms of The Crowns of The Teeth

In order to prevent the rapid attrition from exposing In order to prevent the rapid attrition from exposing the occlusal and proximal aspects of stone age man’s the occlusal and proximal aspects of stone age man’s tooth pulps, the teeth evolved into shapes and forms tooth pulps, the teeth evolved into shapes and forms they have at the present time.they have at the present time.Thus, the greatest thickness of the enamel and dentin Thus, the greatest thickness of the enamel and dentin covering the pulp is on the occlusal, incisal, mesial and covering the pulp is on the occlusal, incisal, mesial and distal surfaces.distal surfaces.Whereas the lingual, buccal and labial surfaces of the Whereas the lingual, buccal and labial surfaces of the teeth which are not subjected to attrition are therefore teeth which are not subjected to attrition are therefore relatively thin.relatively thin.


Small Mesio-Distal Diameters of Tooth Necks and Roots

Due to the proximal attrition and mesial migration of Due to the proximal attrition and mesial migration of the tooth crowns, proximal contact is always the tooth crowns, proximal contact is always maintained.maintained.If the tooth roots were as wide as the original unworn If the tooth roots were as wide as the original unworn tooth crowns and if it did not taper off in the direction tooth crowns and if it did not taper off in the direction of the apex, the unerupted portion of the roots of of the apex, the unerupted portion of the roots of neighbouring teeth would soon be in proximal contact neighbouring teeth would soon be in proximal contact along their whole length causing interdental septa of along their whole length causing interdental septa of alveolar bone and periodontal membrane to resorb and alveolar bone and periodontal membrane to resorb and disappear.disappear.The teeth roots thus without support interdentally The teeth roots thus without support interdentally would be useless for mastication.would be useless for mastication.www.indiandentalacademy.com

Tooth Enamel and Alveolar Bone

Tooth enamel is the unalterable rigid substance in the Tooth enamel is the unalterable rigid substance in the body.body.On the other hand alveolar bone is the most plastic of On the other hand alveolar bone is the most plastic of all of the bones in the body.all of the bones in the body. The juxta position anatomically of these opposites, one The juxta position anatomically of these opposites, one rigid and the other plastic, was essential for the rigid and the other plastic, was essential for the evolutionary development of the highly specialized evolutionary development of the highly specialized dental apparatus.dental apparatus.The inertness of the enamel is compensated by the The inertness of the enamel is compensated by the plastic and mutable alveolar bone and periodontal plastic and mutable alveolar bone and periodontal membrane.membrane.


Pupal PainPulpal pain did not evolve to warn of dental caries but Pulpal pain did not evolve to warn of dental caries but to signal that the attrition was approaching the pulp to signal that the attrition was approaching the pulp faster than the secondary dentine which was being laid faster than the secondary dentine which was being laid down.down.This allowed the transfer of chewing to other teeth in This allowed the transfer of chewing to other teeth in another part of the mouth until secondary dentine another part of the mouth until secondary dentine deposition could overtake the too advanced attrition, deposition could overtake the too advanced attrition, thus protecting the pulp from exposure and death.thus protecting the pulp from exposure and death.


Tubercle of Carabelli

It’s a tooth cusp that is often but not always present on It’s a tooth cusp that is often but not always present on the lingual surfaces of upper molars.the lingual surfaces of upper molars.Because of its failure to occlude in civilized man, this Because of its failure to occlude in civilized man, this was regarded as a vestigial remnant.was regarded as a vestigial remnant.As attrition progressed in stone age man,this tubercle As attrition progressed in stone age man,this tubercle occluded with lower antagonizing tooth.occluded with lower antagonizing tooth.The value of this tubercle was that after sufficient The value of this tubercle was that after sufficient occlusal attrition occurred, it increased the available occlusal attrition occurred, it increased the available masticatory surface areas of this teeth.masticatory surface areas of this teeth.


Also as shown in the figures, The Curve of Wilson reverses direction with attrition and tubercle of Carabelli increases overall occlusal surface area.

The arrow denotes the attritional change in the angle of bucco-lingual plane of occlusion of first permanent molars.


Variations of Lengths of Unworn Tooth Crowns.

Its seen that the occluso-cervical lengths of the Its seen that the occluso-cervical lengths of the unworn first permanent molars are greater unworn first permanent molars are greater than that of the second permanent molars.than that of the second permanent molars. The first permanent molar is already in The first permanent molar is already in occlusion several years before the second occlusion several years before the second permanent molar, thus subjected to more permanent molar, thus subjected to more attrition.attrition.So the greater occluso-cervical dimension is So the greater occluso-cervical dimension is needed to compensate for this attrition.needed to compensate for this attrition.


Attritional Occlusion and The Future of Dentistry

Many forms of malocclusion of teeth found in civilized Many forms of malocclusion of teeth found in civilized man are entirely due to absence of tooth wear.man are entirely due to absence of tooth wear.It is evident from the attritional occlusional study that It is evident from the attritional occlusional study that in the orthodontic treatment of many individuals, in the orthodontic treatment of many individuals, reduction of tooth substance must also be carried out.reduction of tooth substance must also be carried out.The development of stone age man’s attritional The development of stone age man’s attritional occlusion is a normal physiologic process in which occlusion is a normal physiologic process in which there is an overall continual but ever changing there is an overall continual but ever changing integration and harmonization of tooth size with jaw integration and harmonization of tooth size with jaw size, tooth migration, repositioning of teeth and ever size, tooth migration, repositioning of teeth and ever changing relationships of teeth and jaws.changing relationships of teeth and jaws.The sum total provides a successfully functional dental The sum total provides a successfully functional dental apparatus.apparatus.


In all this we see how nature has provided for the balance between tooth size and jaw size by maintaining the correct tooth and inter arch relationships.

On the contrary, these basic factors for the correct occlusion are not present in civilized man.

Therefore the harmonious sequence of events does not occur in civilized man. Failure of continual dental arch reduction therefore causes mis placed teeth, ill formed dental arches and malocclusion.

In stone age man’s attritional dentition, centric occlusion does not exist.


Centric occlusion is regarded in civilized man’s textbook normal occlusion as the very hallmark of anatomically correct occlusion and absence of proper centric occlusion is regarded as abnormal.

However as there are no high cusps but just flat worn surfaces of teeth occluding in attritional occlusion, there is nothing to guide the teeth into centric occlusal relation.

Each time stone age man swallows, his teeth seems to occlude differently, some times to one side of the central line and sometimes to the other side.

Some individuals favour mastication on certain teeth using other teeth less frequently.

When teeth become worn so much as to cause pulpal pain, mastication is transferred to less worn teeth.www.indiandentalacademy.com

Dental students should, from the start of their education, be taught the truth concerning occlusion.

The harmful practice of artificially restoring teeth to their original mesio-distal widths and of making approximating teeth meet in point contact when placing fillings as restorations after dental caries is the result of acceptance of the concept of textbook normal occlusion.

Since it is stated now that attritional occlusion is the correct form of occlusion for man the above practices requires serious reconsideration.www.indiandentalacademy.com

It would be a more rational procedure and in conformity with the concept of attritional occlusion to make each successive set of full upper and lower artificial dentures so that there is no more building up of vertical height than is required to compensate for the amount of alveolar resorption continually taking place in edentulous mouths.

Stone age man’s jaws remained at a constant distance apart in adulthood.

Therefore, it is logical to keep the edentulous jaws a constant distance apart by means of alterations to artificial dentures instead of continually increasing the intra alveolar distance.


The current practice of grinding the buccal cusps of upper molars and the lingual cusps of lower molars when equilibrating the teeth needs reconsideration in view of the fact that it is the lingual cusps of upper molars and the buccal cusps of the lower molars that become worn to the greatest extent in stone age man’s attritional occlusion.



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attritional occlusion - ortho / orthodontic courses by indian dental academy

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