developing occlusion-clinical implications and variations

DEVELOPING OCCLUSION-clinical

implications and variations.

PREDENTATE PERIOD

Gum pads

Maxillary- horse shoe shaped

Mandibular

Anterior open bite Contact posteriorly

They are pink, firm and fibrous

Grooves and Sulci seen

Clinical implications or variations

NATAL TEETH AND NEONATAL TEETH

PRIMARY DENTITION: from 6 months to 6 years of age.

As a general rule, the mandibular dentition precedes the maxillary dentition, except for the

maxillary lateral incisors.

Chronology of eruption of primary teeth

Lower central incisors

Upper central incisors

Upper lateral incisors

Lower lateral incisors

First molars

Canines

Second molars

Clinical implications or variations

Clinical implications or variations

Neonatal teeth

Eruption Cyst

Characteristics of Primary Dentition

• OVERJET• OVERBITE • SPACES IN DENTITION• RELATIONSHIP OF SECOND

DECIDUOS MOLARS

Sagittal relationship in Primary Dentition

What is ‘OVERJET’?

The incisors usually are in normal overjet relation of 1mm or in an edge to edge relationship.

Sagittal relationship in Primary Dentition

Vertical relationship in Primary Dentition

What is ‘OVERBITE?

Vertical relationship in Primary Dentition

Overbite reduces throughout the primary dentition until the incisors are edge to edge, which can contribute to marked attrition.

Clinical implications or variations• Influence of habits like thumb and digit sucking may lead to : -Increased overjet -Anterior open bite

Cross bite

Spaces in primary teeth

Generalized spacing

Primate spaces

• No spacing• Crowding in

primary teeth

Clinical implications or variations

This leads to increased probability of crowding in permanent dentition as dental arch length

anterior to second primary molars does not increase after their eruption

Usually because of larger mandibular second molars, the distal surfaces of the occluding second molars are

flush, whereby the term "flush terminal plane" or straight terminal plane.

Determining the terminal plane relationships in theprimary dentition stage is of great importance as it

guides the erupting first permanent molars into occlusion

Terminal plane relationship between the distal surfaces of the maxillary and mandibular second

primarymolars.

A, Flush terminal planes. B, Mesial step with the C, Distal step with the mandibular plane mesial mandibular plane to the maxillary plane. distal to maxillary plane.

Clinical implications or variations

MIXED DENTITION: from 6 years to 12 years of age.

First transitional period

Characterised by: Eruption of Permanent First Molars Eruption of Incisors

Chronology of eruption of permanent teeth

Clinical implications or variations

Eruption of Permanent First Molars

CLASS l MOLAR RELATION

CLASS ll MOLAR RELATION

CLASS lll MOLAR RELATION

• The FIRST PERMANENT MOLARS when erupt , they utilise the spaces present in the primary teeth to drift mesially. This is called

EARLY SHIFT OF PERMANENT MOLARS

• FORWARD GROWTH OF MANDIBLE

Eruption of Permanent First Molars

Factors that change molar relationship pattern in primary molars to that in permanent molars:

The first Permanent Molars may erupt into one of the following occlusal relationships

Clinical implications or variations

The maxillary arch, on the average, has just enough space to accommodate the permanent lateral incisors when they erupt. In the mandibular arch, however, when the lateral incisors erupt, there is on the average 1.6 mm less space available for the four mandibular incisors than would be required to perfectly align them.

This difference between the amount of space needed for the incisors and the amount available for them is called the "incisor liability." ‘INCISOR LIABILITY’

Eruption of Permanent Incisors

Because of the incisor liability, anormal child will go through a transitory stage of mandibular incisor crowding at age 8 to 9 even if

there will eventuallybe enough room to accommodate all the

permanent teeth in good alignment

Where did the extra space come from to align these mildly crowded lower incisors?

Most jaw growth is in the posterior, and there is no mechanism by which the mandible can easily become longer in its anterior region.

Rather than from jaw growth per se, the extra space comes from three sources:

• Proclination of incisors• Eruption of incisors in a wider arc• Utilization of spaces of primary dentition• Increase in inter canine width

7 years old 9 years old 14 years old

Eruption of Permanent Maxillary Incisors

UGLY DUCKLING STAGE

Clinical implications or variations

UGLY DUCKLING STAGE

Clinical implications or variations

Diastema may be caused by an erupted or unerupted Supernumery tooth in midline(1) or a low frenum(2)

(1)

(2)

Clinical implications or variations

Thumb sucking and digit habits may lead to anterior openbite

Clinical implications or variations

Sometimes the deciduous incisor may be retained leading to palatalEruption of Maxillary Incisor

Clinical implications or variations

Permanent Maxillary Incisors may develop palatally Leading to CROSSBITE

Intertransitional period

This stage is characterized by continued eruption of already

erupted permanent teeth. No significant changes occur.

Second transitional periodThis period, characterized by shedding of the primary canines and molars, emergence of the permanent canines, premolars,

and permanent second molars

Leeway space;1.8mm in maxilla 3.4 mm in mandible

This leeway space is utilized by permanent molars as they drift mesially. This is called late mesial shift. So that a flush terminal relationship is converted into a class I molar relationship

Mandibular molar normally moves mesially more than its maxillary counterpart.

Clinical implications or variations

Improper utilization of LEEWAY SPACE may lead to CROWDING

WHY??

BECAUSE:

Even if incisor crowding is present, the leeway space is normally taken up by mesial movement of the permanent molars.

SOLUTION: An opportunity for orthodontic treatment is created at this time.

PERMANENT DENTITION: from 12 years of age to eruption of third

molars

The overbite often ranges between 10% and 50%, and the overjet ranges

between 1.0 and 3.0 mm.

PERMANENT DENTITION

Intercanine width : canine to canine.

- ↑ 1-2 mm during primary dentition.- ↑ 3 mm in mixed dentition. Growth is completed around 9 years.

MaxillaMandible

Development of the dental arches

Changes in Dental Arches from 6 TO 13 yrs

Clinical implications or variations

Tooth – jaw size discrepancy may lead to (1)CROWDING or(2) DENTAL PROTRUSION

(1)

(2)

TEETHING

Teething is the process by which an infant's teeth sequentially appear by breaking through the gums

TEETHING

The process of teething is sometimes referred to as "cutting teeth".

TEETHINGSIGNS:• General irritability• Disturbed sleep• Loss of appetite • Chewing of objects • Bruises/swelling in gums:Some blood and bruising during

teething is common in most infants and babies:Not all babies bleed from the mouth when teething, but in some cases, a pocket of blood in the gum just above the tooth ruptures. eruption isn't any more painful than usual. It just looks scary to parents!

• Excess salivation

• Running nose • Teething has not been shown to cause fever or diarrhea. A

slight rise of temperature may occur when the teeth come through the gum, but this does not make a baby ill.

Historical management of teething

• . Remedies that have been prescribed for teething through the ages have included blistering, bleeding, placing leeches on the gums, and applying cautery to the back of the head!

• Lancing • Systemic medicamentsOpiates and poisons such as lead acetate, mercurials and bromide. many of these compounds are actually causative of the symptoms associated with teething!

• The teething relief method under constant debate is the age-old remedy of rubbing rum or whiskey on the baby's gums.

Current methods of the management of teething

Non-pharmacological management• Teething rings • Hard, non-sweetened rusks made from flour and wheatgerm with no sugar or sweetener • Reassurance

Pharmacological management• Topical agents• Systemic analgesics

‘Alternative' holistic medicine• acupressure, • aromatherapy,• and homeopathy

DIFFERENCES BETWEEN PRIMARY AND PERMANENT

TEETH