The Developing Occlusion

Theory and Practice of Pediatric Dentistry

Lecture Overview

Occlusion

Eruption

Effects of premature tooth loss

Changes during the development of Occlusion

Introduction

Ideally, as the occlusion develops from the primary dentition through the transitional to the permanent dentition, a sequence of events occurs in an orderly fashion.

Final goal of occlusion is to be

Functional

Esthetical

Stable

Desired Eruption sequence in the Permanent Dentition

Variables that influence eruption

Genetics

Familial tendencies, African Americans > Caucasians, Females > Males

Environmental

Delayed in LBW and ventilator dependency

Systemic

Endocrinal, eg: hypopituitarism, hypothyroidism

Forces acting on a Tooth

Natural Space Maintenance

The natural tooth is the best space maintainer - functional, correct size & exfoliates appropriately.

Ensure that you ideally restore all the interproximal contours when you restore teeth.

Strive to save the tooth even if pulp treatment is needed.

Effects of Premature loss of a Tooth

Loss of arch circumference

Delayed or accelerated eruption of succedaneous teeth

Generalized Spacing

40% of children have spacing in their primary dentition.

Allows for adequate space for the permanent dentition.

Tooth migration and Arch Changes during Development of Occlusion

Primate Spaces

Early Mesial Shift

Late Mesial Shift

Secondary Spacing

Leeway Space

Primate Spaces

Seen in the primary dentition only.

Incidence of 70% in the mx and 63% in the md.

Congenital rather than developmental.

2 distinct diastema’s -

Mx laterals and canines - 1.7 mm

Md canines and first molars - 1.5 mm

Early Mesial Shift

Mesial migration of the erupting md permanent molar

Uses the md primate space

Seen in arches (63%) have the md primate space

Occurs around 6 years of age

Late Mesial Shift

Mesial migration of erupted md permanent molar after the loss of the primary second molar

Uses the Leeway space

Seen around the age of 11 yrs

Seen in all cases

Secondary Spacing

Usually occurs in primary arches that have no primary spacing.

When the md permanent lateral incisors erupt, the primary md canines are moved laterally, thus creating space for the maxillary permanent lateral incisors.

Leeway Space

Premolars are smaller than the primary teeth they replace

This extra space is called Leeway space

This is the space that is used up in the Late Mesial Shift

Leeway space in each quadrant

Mx - 1.5 mm

Md - 2.5 mm

Occlusal Relationship of Primary Teeth

3 types

Straight terminal plane - 76% incidence, Class I or II

Mesial Step - 14% incidence, ideal, Class I

Distal Step - 10% incidence, abnormal, Class II

Arch Length

The distance from the distal surface of the second primary molar (or mesial surface of the first permanent molar) on one side of the arch to that same surface on the opposite side.

Decrease in circumference as child grows - seen during the mesial migration of first permanent molar during the late mesial shift.

Changes in Arch Length

Arch Length Analysis

Several different types can be used

Types

Nance Analysis - based on radiographic pictures and is not used much these days.

Moyer’s Mixed Dentition Analysis - based on a correlation of tooth size and the use of a prediction chart.

Summary

The development of the occlusion is an orderly sequence of events.

Any variation in this sequence will result is some form of malocclusion.

There are several forces that act on a tooth in the arch.

Natural teeth are the best space maintainers.

There are several spaces present in the primary dentition that allow space for the larger permanent dentition.


	Occlusion
	Eruption
	Effects of premature tooth loss
	Changes during the development of Occlusion


	Ideally, as the occlusion develops from the primary dentition through the transitional to the permanent dentition, a sequence of events occurs in an orderly fashion.
	Final goal of occlusion is to be
		Functional
		Esthetical
		Stable


	Genetics
		Familial tendencies, African Americans > Caucasians, Females > Males
	Environmental
		Delayed in LBW and ventilator dependency
	Systemic
		Endocrinal, eg: hypopituitarism, hypothyroidism


	The natural tooth is the best space maintainer - functional, correct size & exfoliates appropriately.
	Ensure that you ideally restore all the interproximal contours when you restore teeth.
	Strive to save the tooth even if pulp treatment is needed.


	Loss of arch circumference
	Delayed or accelerated eruption of succedaneous teeth


	40% of children have spacing in their primary dentition.
	Allows for adequate space for the permanent dentition.


	Primate Spaces
	Early Mesial Shift
	Late Mesial Shift
	Secondary Spacing
	Leeway Space


	Seen in the primary dentition only.
	Incidence of 70% in the mx and 63% in the md.
	Congenital rather than developmental.
	2 distinct diastema’s -
		Mx laterals and canines - 1.7 mm
		Md canines and first molars - 1.5 mm


	Mesial migration of the erupting md permanent molar
	Uses the md primate space
	Seen in arches (63%) have the md primate space
	Occurs around 6 years of age


	Mesial migration of erupted md permanent molar after the loss of the primary second molar
	Uses the Leeway space
	Seen around the age of 11 yrs
	Seen in all cases


	Usually occurs in primary arches that have no primary spacing.
	When the md permanent lateral incisors erupt, the primary md canines are moved laterally, thus creating space for the maxillary permanent lateral incisors.


	Premolars are smaller than the primary teeth they replace
	This extra space is called Leeway space
	This is the space that is used up in the Late Mesial Shift
	Leeway space in each quadrant
		Mx - 1.5 mm
		Md - 2.5 mm


	3 types
		Straight terminal plane - 76% incidence, Class I or II
		Mesial Step - 14% incidence, ideal, Class I
		Distal Step - 10% incidence, abnormal, Class II


	The distance from the distal surface of the second primary molar (or mesial surface of the first permanent molar) on one side of the arch to that same surface on the opposite side.
	Decrease in circumference as child grows - seen during the mesial migration of first permanent molar during the late mesial shift.


	Several different types can be used
	Types
		Nance Analysis - based on radiographic pictures and is not used much these days.
		Moyer’s Mixed Dentition Analysis - based on a correlation of tooth size and the use of a prediction chart.


	The development of the occlusion is an orderly sequence of events.
	Any variation in this sequence will result is some form of malocclusion.
	There are several forces that act on a tooth in the arch.
	Natural teeth are the best space maintainers.
	There are several spaces present in the primary dentition that allow space for the larger permanent dentition.