Factors affect occlusal development Prepared by: Dr Mohammed Alruby المحايد هو شخص لم ينصر الباطل ولكن من المؤكد انه خذل الحق Factors affect occlusal development General factors: 1- Skeletal 2- Muscular 3- Dental Local factors: 1- Aberrant developmental position of teeth 2- Presence of supernumerary teeth 3- Hypodontia- congenital absence of certain teeth 4- Effects of certain habits activities 5- Localized soft tissue anomalies Skeletal factors affect occlusal development = Any pathology condition affecting growth of the jaws is likely to have marked effect on the occlusion of the teeth = As the teeth are set in the jaws, the relationship of the jaws to each other will have a large influence on the relationship of the dental arches. = jaws relationship can be considered under three headings: 1- Jaws relationship to cranial base: By relating the jaws to anterior cranial base as it anterior or posterior in position 2- Jaws relation to each other: Class I: upper and lower in normal relation together Class II: lower posterior to upper Class III: in which lower arch forward in occlusion to upper Variation in skeletal relationship may be due to: - Variation in jaws size - Variation in position of jaws to cranial base Both these variations can affect the type of occlusion as in cases of skeletal I or II or III === vertical relationship of upper and lower also affect the occlusion, mandible with high gonial angle tends to produce a longer vertical dimension of the face. Mandible with low gonial angle tends to produce a shorter vertical dimension of the face 3- Alveolar bone in relation to basal bone: Skeletal relationship refers to basal bone Alveolar bone supported by basal bone Alveolar bone supports the teeth Muscle factors affect occlusal development = the muscle of tongue, cheeks are of particular importance in guiding the teeth into their final position = variation in muscle form and function can affect the position and occlusion of the teeth Lips: = Lips are usually brought together during swallowing and speech movements, if they are insufficient size so need extra force to close together with more muscle contraction that have high effect on the teeth related to it during eruption =the lower lip tends to be further back than the upper as in skeletal class II and further forward as in class II, this not only increase the difficulty to put the lips together but also may cause the lower lip to modify the eruptive path of the upper incisors = the lower lip plays more part than upper lip in functional movement and governing the position of incisors teeth Tongue: Tongue size: if tongue large size so it not has adequate space between arches so it fills space between upper and dental arches so prevent full vertical development of dento-alveolar structure Tongue position: normally tongue lateral border touch the lingual cusps of molars and premolars Tip of tongue: rest at the lingual surface between the lower in

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Dr Mohammed Alruby
Factors affect occlusal development
Prepared by:
Dr Mohammed Alruby
‫الحق‬ ‫خذل‬ ‫انه‬ ‫المؤكد‬ ‫من‬ ‫ولكن‬ ‫الباطل‬ ‫ينصر‬ ‫لم‬ ‫شخص‬ ‫هو‬ ‫المحايد‬
Factors affect occlusal development

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Dr Mohammed Alruby
General factors:
1- Skeletal
2- Muscular
3- Dental
Local factors:
1- Aberrant developmental position of teeth
2- Presence of supernumerary teeth
3- Hypodontia- congenital absence of certain teeth
4- Effects of certain habits activities
5- Localized soft tissue anomalies
Skeletal factors affect occlusal development
= Any pathology condition affecting growth of the jaws is likely to have marked effect on the
occlusion of the teeth
= As the teeth are set in the jaws, the relationship of the jaws to each other will have a large
influence on the relationship of the dental arches.
= jaws relationship can be considered under three headings:
1- Jaws relationship to cranial base:
By relating the jaws to anterior cranial base as it anterior or posterior in position
2- Jaws relation to each other:
Class I: upper and lower in normal relation together
Class II: lower posterior to upper
Class III: in which lower arch forward in occlusion to upper
Variation in skeletal relationship may be due to:
- Variation in jaws size
- Variation in position of jaws to cranial base
Both these variations can affect the type of occlusion as in cases of skeletal I or II or III
=== vertical relationship of upper and lower also affect the occlusion, mandible with high gonial
angle tends to produce a longer vertical dimension of the face. Mandible with low gonial angle
tends to produce a shorter vertical dimension of the face
3- Alveolar bone in relation to basal bone:
Skeletal relationship refers to basal bone
Alveolar bone supported by basal bone
Alveolar bone supports the teeth
Muscle factors affect occlusal development
= the muscle of tongue, cheeks are of particular importance in guiding the teeth into their final
position
= variation in muscle form and function can affect the position and occlusion of the teeth
Lips:
= Lips are usually brought together during swallowing and speech movements, if they are
insufficient size so need extra force to close together with more muscle contraction that have high
effect on the teeth related to it during eruption

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Dr Mohammed Alruby
=the lower lip tends to be further back than the upper as in skeletal class II and further forward
as in class II, this not only increase the difficulty to put the lips together but also may cause the
lower lip to modify the eruptive path of the upper incisors
= the lower lip plays more part than upper lip in functional movement and governing the position
of incisors teeth
Tongue:
Tongue size: if tongue large size so it not has adequate space between arches so it fills space
between upper and dental arches so prevent full vertical development of dento-alveolar structure
Tongue position: normally tongue lateral border touch the lingual cusps of molars and premolars
Tip of tongue: rest at the lingual surface between the lower incisors
Dorsum of the tongue touch palate. Any change than normal position will allow more effect on
normal development of dental structure and occlusion development
Tongue function: mastication, swallowing, speech
- Normal tongue function allows normal development of dental structure and occlusion
- Essential features of normal swallowing of solid food and saliva
1- Lip closure
2- Teeth in contact occlusally
3- Tongue elevated to palate
4- Momentary clinching of the teeth as food pass into pharynx
Any change from normal tongue behavior during function prevent normal development of
occlusion as:
- Tongue thrust swallowing
- Adaptive resting posture or adaptive swallowing may produce incomplete overbite
Speech:
The effect of speech on occlusal development and affects the tooth position on speech are not fully
understood and any apparent effects are likely to be influenced by other inter-related factors
Thumb and finger sucking:
Effect of thumb sucking habits on occlusal development are variable and depend on the occlusal
pattern of habits activity
The position of thumb and duration and manner of sucking affect the shape and pattern of deformity
Mostly there is anterior open bite and proclination of upper anterior and retroclination of lower
anterior
Some cases may be having buccal cross bite with collapsed upper arch due to pressure from
buccinator muscle
N: B: the muscular environment of the teeth does not have a fixed pattern of activity, but can
change during growth, with consequent changes in both position
Dental factors affecting occlusal developments
a- Excessive dentition size:
Excessive dentition size in relation to dental arch size has the following effects:
1- Overlapping and displacement of teeth, this particularly affect the last teeth erupts in any
group
2- Impaction of teeth: occurs when eruption is completely blocked by other teeth due to
crowding

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Dr Mohammed Alruby
3- Mesial movement of teeth: mesial movement into spaces created by inter-proximal attrition,
it does not occur in every individual even when spaces are made in the dental arch
N: B: mesial migration occurs as normal growth process, it is a physiologic process
b- Early loss of primary teeth:
1- Affect masticatory function
2- Affect speech if is anterior segment
3- Migration of the teeth to extracted area
4- Overeruption of opposing teeth
5- Can affect the mandibular posture as in cases of lost deciduous molar and child habits to
bite in anterior segment that can lead to pseudo class III
6- Affect position of permanent teeth through:
- Affect the shape of dental arch: if there is loss of primary teeth, there is collapse in anterior
segment in lingual direction
- Affect size of dental arch, due to mesial migration of teeth to extraction space that, may be
lead to crowding if there is no enough space in arch to the successional teeth
== a symmetric loss of primary teeth may lead to a symmetry dental arch with variation in the
midline which can difficult to treat, so it is important to do a symmetric extraction in the arch
Local factors affecting development of occlusion
1- Aberrant developmental position of individual teeth:
= when the tooth changes its position due to any cause during development lead to abnormal path
of eruption and later affect its position in the arch
= the developmental position may be affected by trauma as in upper incisors that may be lead to
malposed or dilacerated root, OR, unknown etiology as in permanent canine upper
2- Supernumerary teeth:
Occurs more frequently in the premaxilla than other part of jaws
Prevalence: 1% of populations which may be one of the following:
a- Supplemental teeth:
Supernumerary with normal form tooth as extra upper lateral or lower incisors in permanent
dentition
Main effect: increase crowding potential, it is difficult to differentiate between normal and
supplemental one
b- Conical teeth:
Supernumerary tooth occurs in premaxilla near to midline, its often called mesiodens
May occurs singly or pairs
Inverted in shape as it not erupts into the mouth
Appear early in development
Root formation begin early then permanent central incisors
Erupt during childhood
Can causes: malposition of teeth adjacent to it, and midline diastema
c- Tuberculate teeth:
Occurs in premaxilla
Later in its development than conical
Root formation is later than central incisors

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Dr Mohammed Alruby
Appear in palatal aspect of permanent central incisor
Do not erupt in childhood
Unilateral or bilateral – may represent third dentition
Can cause: delayed eruption of permanent central incisors
3- Hypodontia:
Developmental absence of one or more teeth
Can modify the occlusion and position of teeth by effect on:
a- Form of teeth: incisors and canine may be form cusp deficiencies in premolars and molars
b- Position of teeth: if there is a large number of missing lead to malposition of teeth
c- Growth of jaws:
- Absence of large number of teeth cause reduction in growth of alveolar bone
- Reduced vertical dimension occlusion due to missing large number of teeth due to defect of
alveolar height
- Reduction in transverse and anterior posterior dimension
d- Upper labial frenum: lead to midline diastema and need resection to its normal position
N: B: it is best to wait until the permanent canines erupted before carrying out frenectomy, to give
maximum chance of spontaneous closure of the diastema during growth