etiology of - dental.subharti.orgdental.subharti.org/orthodontics/etiologymalocclusion.pdf · leads...

Etiology

of

Malocclusion DEPARTMENT OF ORTHODONTICS

SUBHARTI DENTAL COLLEGE

SWAMI VIVEKANAND SUBHARTI UNIVERSIT Y

Dr Kumar Amit, Subharti

Dental College, SVSU

Presented By:

Dr Kumar Amit

identify malocclusion



Introduction :

Malocclusions may involve four tissue systems

m Teeth

m Bones

m Muscles

m Nerves



Another way to classify malocclusion is to divide them into three groups

m Skeletal dysplasias

m Dental dysplasias

m Skeleto dental dysplasias



Etiologic factors

Inherited pattern of malocclusion : polygenic

Exogenic influence : - systemic or localized

- static or functional



Interaction between hereditary and

environmental factors



Causes of malocclusion



Classification of etiologic

factors of malocclusion

ACCORDING TO MOYERS

Heredity

T Neuro muscular system

T Bone

T Teeth

T Soft parts (other than nerve and muscle)

Developmental defects of unknown origin

Trauma

T Prenatal trauma and birth injuries.

T Post natal trauma.



Physical agents T Pre natal

T Post natal

Habits TThumb and finger sucking, tongue

thrusting, lip biting etc

Disease T Systemic diseases

T Endocrine diseases

T Local diseases

Malnutrition Dr Kumar Amit, Subharti


According to Salzmann

Salzmann’s diagrammatic representation of the etiologic factors in

malocclusion embodies prenatal and post natal factors.

It clearly shows the genetic, differentiative and congenital factors

that make up the prenatal elements of causation, which can

influence one or all of the postnatal components- developmental,

functional, environmental. Dr Kumar Amit, Subharti


According to Graber

General Factors

Heredity (The inherited pattern)

Congenital Defects

T Cleft palate

T Torticollis

T Cleidocranial dysostosis

T Cerebral palsy

T Syphilis etc.



Environment

T Pre natal

Q Trauma

Q Maternal diet

Q Maternal metabolism

Q German measles etc.

T Post natal birth injury

Q Cerebral palsy

Q TMJ injury etc.



Pre disposing metabolic climate and disease

T endocrine imbalance

T metabolic disturbances

T infectious diseases

Dietary problems

T nutritional deficiency



Abnormal pressure habits and functional aberrations

Abnormal suckling

Forward mandibular posture

Non physiologic nursing

Excessive buccal pressures

Thumb and finger sucking

Tongue thrust and tongue sucking

Lip and nail biting

Abnormal swallowing habits

(improper deglutition)

Speech defects



Respiratory abnormalities

(mouth breathing)

Tonsils and adenoids (compensatory tongue position)

Psychogenic tics and Bruxism

Posture

Trauma and Accidents



Local factors

Anomalies of number

T Supernumerary teeth

T Missing teeth

Q Congenital absence or loss due to

accidents, caries etc

Anomalies of tooth size

Anomalies of tooth shape

Abnormal labial frenum, mucosal barriers



Premature loss

Prolonged retention

Delayed eruption of permanent teeth

Abnormal eruptive path

Ankylosis

Dental caries

Improper dental restorations



ACCORDING TO PROFFIT

Specific causes

T Disturbances in embryologic development

(teratogens)

T Skeletal growth disturbances

Q Intrauterine molding

Q Birth trauma to mandible

Q Childhood fractures or the jaw

T Muscle dysfunction



TAcromegaly and hemi mandibular hyper trophy

TDisturbances of dental development

Q Congenitally missing teeth

Q Malformed and supernumerary teeth

Q Interferance with eruption

Q Ectopic eruption

Q Early loss of primary teeth

Q Traumatic displacement of teeth



Genetic influences

Environmental influences

T Equilibrium theory and development of dental occlusion

T Functional infuence on dento facial development.



General factors

Heredity

A child may have facial features that markedly resemble those of his father or mother, or the net result may be a combination of features from each parent. It is also to be noted that, a single gene is not responsible for a particular malocclusion and it may be due to the combined action of different types of Genes

Heredity could be considered significant in determining the following characteristics



T Tooth size

T Width and length of arch

T Height of palate

T Crowding and spacing of teeth

T Overjet

T Position and conformation of perioral musculature to

tongue size and shape

T Soft tissue peculiarities

T Facial asymmetries

T Macorgnathia and micrognathia

T Macrodontia an microdontia



TOligodontia and anodontia

T Tooth shape variations

(peg laterals, Carabellis cusps, mamelons etc)

TCleft palate and hare lip

TDiastemas

TDeep bite

TRotation of teeth

TMandibular retrusion

TMandibular prognathism



Congenital defects

Cleft lip and palate

Congenital defects life cleft lip and palate separately or in combination are among the most frequent congenital deformities of mankind. It is not often possible for the dentist to compensate for residual post surgical abnormalities. In a unilateral cleft, the teeth or one side are usually in lingual cross bite with the opposing lower teeth. Many times the premaxilla is displaced anteriorly, or, because of the tightly repaired lip, the whole pre maxillary structure is forced lingually. The maxillary incisors in this type are badly malposed with bizarre axial inclinations. In the area of cleft, teeth are often jumbled. Maxillary lateral incisors may be missing, atypical in shape or ‘twinned’ Dr Kumar Amit, Subharti


Cerebral palsy

Paralysis or lack of muscular co-ordination due to an intra cranial lesion

Complete lack of motor control resulting in abnormal muscular function in masticaction, deglutition, speech and respiration.

Abnormal pressure habits lead to malocclusion Dr Kumar Amit, Subharti


Torticollis

Shortening of the sternocleido mastoid muscle causing profound

changes in the bony morphology of the cranium and the face

Characterised by “wry neck”

Bizarre facial asymmetries and uncorrectable malocclusions if not

treated early



Cleidocranial dysostosis

Maxillary retrusion and possible mandibular protrusion

Retained deciduous teeth

Retarded eruption of permanent teeth

Short and thin permanent teeth roots

Super numerary teeth



Congenital Syphilis

Abnormally shaped teeth



Pre natal

Post natal

Environment



Pre natal

Teratogens: Chemical and other agents capable of producing

embryologic defects if given at critical time are called teratogens

Aminopterin

Aspirin

Cigarette smoke (hypoxia)

Cytomegalovirus

Anencephaly



Microcephaly, hydrocephaly,

microphthalmia

Dilantin

Ethyl alcohol

6-Mercaptopurine

13-cis Rentinoic acid

(Accutane)


Central mid-face deficiency

Cleft Palate

Retinoic acid syndrome: malformations

virtually same as hemifacial microsomia,

Treacher Collins syndrome

Rubella virus

Thalidomide

Microphthalmia, cataracts, deafness

Malformations similar to hemifacial

microsomia, Treacher Collins syndrome

Toxoplasma Microcephaly, hydrocephaly,

microphthalmia

X-radiation

Valium

Vitamin D excess

Microcephaly

Cleft and palate

Premature suture closure Dr Kumar Amit, Subharti


Intrauterine molding

Pressure against the developing face prenatally can lead to distortion of rapidly growing areas. Eg: an arm is pressed across the face in utero resulting in severe maxillary deficiency.

Other factors that may affect are trauma, maternal diet, maternal metabolism and German measles

Dr Kumar Amit, Subharti Dental

College, SVSU

Birth trauma

In some difficult births use of forceps to the head to assist in delivary might damage either or both TMJ. Heavy pressure in the area of TMJ could cause internal haemorrhage, loss of tissue and a subsequent under development of the mandible

Childhood fractures: Falls that produce condylar fractures may cause marked facial asymmetries

Extensive scar tissue, from a burn may also produce malocclusions

Post natal

Dr Kumar Amit, Subharti Dental College,

SVSU

Some specific endocrinologic diseases may be potent makers of malocclusion. Diseases with a paralytic effect, such as poleomyelitis are capable of producing malocclusions.

Disease with muscle malfunction, such as muscular dystrophy and cerebral palsy also have deforming effects on dental arch

Pre disposing metabolic climate and

diseases



Hypothyroidism

Abnormal resorption patterns

Delayed eruption pattern

Gingival disturbances

Retained deciduous teeth



Acromegaly

Which is caused by an anterior pituitary

tumor that secrete excess amounts of GH, excessive

growth of mandible may occur, creating a skeletal

class III malocclusion in adult life. Also multiple root

resorption may be found.



Nutritional deficiency

Disturbances such as rickets, scurvy and berry-

berry can produce severe malocclusions. Main problem is

upsetting of the dental developmental time tables. The

resultant premature loss, prolonged retention, poor tissue health

and abnormal eruptive paths lead to malocclusion



Non nutritive sucking habits, Includes all

sucking habits

T Thumb sucking

T Finger sucking

T Pacifiers etc.

Abnormal pressure habits and functional

aberrations



Dento facial changes associated with prolonged non nutritive sucking habits are

T Increased proclination of upper incisors

T Increased maxillary arch length

T Increased clinical crown length of max incisiors

T Increased atypical root resorption in primary central incisors



T Increased retroclination of mandibular incisors

T Increased overjet

T Decreased over bite

T Increased unilateral and bilateral class II occlusion

T Increased lip incompetence

T Tongue thrust

T Speech defects, especially lisping



Lip biting

T Involves the lower lip which is turned inwards and pressure is exerted on the lingual surfaces of maxillary anteriors

T Proclined upper anteriors and retroclined lower anteriors

T Hyper trophic and redundant lower lip

T Cracking of lips

Lip habits



Nail biting

Does not produce gross malocclusion. But

minor local tooth irregularities like

T Rotation

T Wear of incisal edge

T Minor crowding.



Tongue thrust Defined as a condition in which the tongue makes contact with

any teeth anterior to the molars during swallowing

It has to be remembered at this time that there is a controversy regarding Tongue thrust as an etiologic factor of anterior open bite. According to Graber and Moyers, Tongue thrust definitely leads to anterior open bite. Proffit contradicts this fully and according to him, it is an already existing anterior open bite that leads to Tongue thrusting habit

T Proclination of anterior teeth

TAnterior open bite

T Bimaxillary protrusion

T Posterior open bite in case of

lateral Tongue thrust

T Posterior cross bite



Mouth breathing

Mouth breathing can result in altered jaw and tongue posture which could alter the oro-facial equilibrium there by leading to malocclusion

T Long and narrow face

T Short and flaccid upper lip.

T Contracted upper arch with possibility of

posterior cross bite

T Increased overjet as a result of flaring of the incisors.

T Dryness of the mouth predisposes to caries.

T Anterior open bite



Bruxism

Grinding of teeth for non functional purposes

T Occlusal wear facets

T Fractures of teeth and restorations

T Mobility of teeth.

T Tenderness and hypertrophy of masticatory muscles

T TMJ pain



Tongue size as well as function is an important

consideration. Aglossia can result in narrowing of the upper dental arch with severely malpositioned teeth and crowding. Where as Macroglossia can lead to widening of dental arches, spacing and open bite.



Anomalies in number of teeth

T Super numerary teeth

T Missing teeth

Local factors



Super numerary teeth

The presence of extra tooth obviously has great potential to disrupt normal occlusal development. Early intervention and to remove it is usually required to obtain reasonable alignment and occlusal relationships. Most common-mesiodens.

Also lateral incisors, extra premolars, fourth molars multiple super numerary teeth are found in cleidocranial dysplasia and other congenital deformities like cleft lip and cleft palate



Missing teeth Congenital absence

Due to accidents / caries

Order of frequency

T Max and mandibular 3rd molars

T Max laterals

T Mandibular 2rd premolars

T Mandibular incisors

T Maxillary second premolars

Anodontia–complete absence

Oligodontia–congenital absence of many, but not all teeth

Hypodontia – absence of only a few teeth



Quite frequently it has been noted that, one maxillary lateral incisor will be of normal size and configuration while the other is small. Anomalies of size are relatively frequent in the mandibular pre molar area

Anomalies of tooth size



Anomalies of Tooth Shape

Most frequent – “Peg Lateral”

Leads to excessive spacing. Anomalies of shape occur as a result of developmental defects like amelogenesis imperfecta, hypoplasia, Gemination, Dens in Dente, Odontomas, Fusions, Congenital syphilitic aberations such as Hutchinson’s incisors and mulberry molars.



Abnormal labial Frenum

If the frenum is thick, it prevents the closure of diastema (which is normal during mixed dentition prior to the eruption of canines)

In these cases a frenectomy is indicated



Premature loss of deciduous teeth

The early loss of permanent teeth should be considered as a “Malocclusion Maker”

Deciduous teeth not only serve as organs of mastication, but as space savers for permanent teeth. Loss of a deciduous 2nd molar will lead to mesial drift of the 1st permanent molar and blocking of erupting 2nd premolars. In this cases appropriate space maintainers should be given



Prolonged retention and abnormal

resorption of deciduous teeth

If the roots of the deciduous teeth are not resorbed properly, uniformly or on schedule, the permanent successors may be either withheld from eruption, or they may be deflected into malposition



Delayed eruption of Permanent teeth

Endocrine disorders like hypothyroidism

Presence of supernumerary teeth or

deciduous root

Mucosal or Bony barrier



This is usually a secondary manifestation of a primary disturbance

T Severe crowding

T Super numerary tooth

T Retained deciduous tooth / root fragment

T Bony barrier

T Dentigerous cysts

Another form of abnormal eruption is referred as ectopic eruption. Most common form is a permanent tooth erupting through the alveolar process causing resorption on a contiguous deciduous tooth or permanent teeth , rather than its predecessor. Eg; maxillary first molar, causing resorption of maxillary deciduous second molar.

Abnormal eruptive path



Ankylosis

Ankylosis or partial ankylosis occurs relatively frequently during 6-12 year age period. Ankylosed deciduous teeth should be identified and treated by removal or building up or surgical subluxation along with space maintainers.

Permanent teeth can also be found to be ankylosed can be due to

T Accidents / trauma

T Congenital diseases like cleidocranial dysostosis



Dental caries

Dental caries should be considered as one of the local factors causing mal occlusion. Caries which leads to premature loss of a deciduous or permanent tooth may cause drifting, axial inclination, over eruption, bone loss etc.



Improper dental restorations

Silver mercury alloy restorations have a tendency to “flow” under pressure. Large proximal restorations change gradually under the assault of occlusal forces, and arch length is increased. This may result in the creation of broken contacts, rotations, crossbite conditions and functional prematurities. Lack of anatomic detail in restoration of cuspal areas of a tooth can permit elongation of opposing tooth.

Loose contacts also leads to food packing, teeth tend to move apart and also leads to bone loss



Knowledge about the various etiological factors of malocclusion will help us to plan the various interceptive and preventive orthodontic procedures.

It also helps in eliminating the etiological factor if it is of a environmental type.

The recognition and reporting of a malocclusion or a condition that could lead to a malocclusion is the most important service that a dentist can provide to his patients. Malocclusion has an important impact on the function and esthetics of the entire dentition. In fact, malocclusion has a detrimental effect on the self esteem of many children, adolescent and adult. If a malocclusion is not recognized by either the dentist or the patient, it cannot be assessed and treated

A sound knowledge about the various factors that lead to malocclusion, will definitely help is to render excellent treatment for our patients with good retention and stability

Conclusion



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