deciduous teeth [compatibility mode]

8/7/2019 Deciduous Teeth [Compatibility Mode]

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Prof Hanaa Aly


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Lecture 1 15 March 2009

Lecture 2 22 March 2009

DECIDUOUS TEETHDECIDUOUS TEETHPRIMARYPRIMARY TEETHTEETH

LectureLecture 11

LectureLecture 22

Lecturer Prof HANAA ALY

Prof Hanaa Aly

Lecturer Prof HANAA ALYLecturer Prof HANAA ALY


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Presented b

DECIDUOUS TEETHDECIDUOUS TEETHPRIMARYPRIMARY TEETHTEETH

Prof. HANAA ALY

/ Professor of Oral Biology

Alexandria University

Prof Hanaa Aly


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deciduous teeth "temporary","milk", or "baby" teethThe term deciduous comes from the Latin word meaning to fall off.

are shed to be replaced by the permanent teeth that succeed them.Shed=complete resorption of the roots

Importance and Functions of Primary Teeth:

1- for efficient chewing (mastication) of food.

2-support for cheeks & lips maintaining a normal facial appearance.

3- for clear speech.4- for maintaining space for eruption of permanent teeth.

Therefore, premature loss of deciduous teeth is to be avoided.

Prof Hanaa Aly


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Essential Differences Between

Deciduous & Permanent Teeth

The deciduous teeth are twenty in number.

Dental formula I 2/2 C1/1 M2/2

There are no premolars in the deciduous set

-lighter in color than are the permanent.

-show physiologic spacing.-The deciduous anterior teeth have a more upright position in jaws,

The permanent teeth are more inclined labially.

-Attrition occurs and a pattern of wearing may be present rapidly.

Prof Hanaa Aly


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Traits of All Deciduous Anterior Teeth :

1- The cervical ridges of enamel at the cervical third on the labial

surfaces and the lingual cingula are much more prominent in

deciduous than in the permanent teeth. These prominent contoursmust be considered in operative procedures.

2-.Usually there are no depressions nor mamelons on the labial

surface of incisors.

3--roots are narrower and longer in comparison with crown

width and length, have a labial inclination. Prof Hanaa Aly


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Traits of All Deciduous Posterior Teeth

1-prominent mesial cervical ridge buccally on deciduous

molars is much more pronounced, especially on first molars

( maxillary and mandibular) .

2 buccal and lingual surfaces of deciduous molar crown are flatter

coronal to the cervical curvatures than these of permanent molars

there is narrowing in the occlusal surfaces buccolingually.

3- crowns and roots of deciduous molars are narrower mesiodistally

at the cervical third than these of permanent molars.

4- occlusal anatomy is shallow. cusps are short almost flat,

occlusal ridges are not pronounced and fossae and sulci are not

as deep as on the permanent molars.

5- deciduous second molars are larger than the deciduous first molars,

different than in the permanent dentition.

6- roots of deciduous molars are relatively more slender and longerthan roots of the permanent molars. They have very short root trunks.

They also flare out more apically, extending beyond the outlines of the

crown. This flare allows, more room between roots fordevelopment of

permanent teeth crowns before it is time for deciduous molars to loose

their anchorage Prof Hanaa Aly


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Comparison of sections of deciduous and permanent teeth shows:

1- enamel is relatively thin and has a consistent depth.

2- dentin thickness between pulp chamber and the enamel is limited.3- pulp chambers are large

pulp horns are high.

root canals are extremely fine

Prof Hanaa Aly


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DECIDUOUS MAXILLARY CENTRAL INCISOR

This tooth resembles the permanent maxillary central incisor except for the following:

much smaller than the permanent

. The crown mesiodistal diameter is wider than its cervico-incisal length

(the opposite is true of the permanent central incisor).

The labial surface is very smooth with no developmental lines in evidence.

lingual surface shows well developed, marginal ridges and cingulum,the cingulum extend, toward incisal ridge dividing lingual fossa into two, a mesial and a distal fossa.

The root is almost twice as long as the crown

Prof Hanaa Aly


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B

DECIDUOUS MAXILLARY LATERAL INCISOR

This tooth is similar to the permanent maxillary lateral incisor except that

it is smaller in size.

It differs from the deciduous central in that

the cervicoincisal length of the crown is greater than its mesiodistal width.

The distoincisal angle is more rounded (Fig.5).

Prof Hanaa Aly


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This tooth is similar to the corresponding permanent mandibular

DECIDUOUS MANDIBULAR Central INCISOR

Prof Hanaa Aly

first incisor except that, it is much smaller

DECIDUOUS MANDIBULAR LATERAL INCISOR

This tooth is similar to the corresponding permanent

mandibular lateral incisor except that, it is much smaller.


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DECIDUOUS MAXILLARY CANINE

Prof Hanaa Aly

s toot s s m ar to t e permanent max ary can ne except or t e o ow ng:

smaller.

crown is more constricted at the cervix

the mesial and distal surfaces are more convex.

The mesial and distal contact areas at the same level, nearly in the centerof the middle third.

The cusp is much longer and sharper than that of the permanent.

It has the mesial slope longer than the distal(opposite to that of permanent).

The root length is more than twice the crown length .


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DECIDUOUS MANDIBULAR CANINE

This tooth resembles the permanent mandibular canine,

it is only much smaller.

Like the permanent mandibular and maxillary canines,the mesial slope shorter than the distal

Prof Hanaa Aly


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DECIDUOUS MAXILLARY FIRST MOLAR

Buccal aspect

It is much wider mesiodistally at contact areas than at cervix.

The occlusal is slightly scalloped with no definite cusp form

large mesiobuccal and a small distobuccal cusps.

The buccal surface is smooth with little evidence of developmental grooves.

The cervical line is convex towards the root and is higher mesially than distally.

The roots: are slender and long,

have a wide spread on a very short root trunk.

All three roots are seen from this aspect. The distobuccal root is shorter than the mesiobuccal

Lingual aspect

The crown converges considerably in a lingual direction. The mesiolingual cusp is the longest and sharpest of all cusps.

The distolingual cusp is poorly developed& sometimes absent resulting in a three cusp type molar.

All three roots are seen from this aspect.

The lingual root is larger than the others


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Mesial aspect

DECIDUOUS MAXILLARY FIRST MOLAR

crown is much wider at cervical third than at occlusal third.

cervical ridge buccally appears over developed (a typical characteristic of this tooth).

mesiolingual cusp is longer and sharper than the mesiobuccal cusp.

cervical line is slightly concave rootwise.

somesiobuccal and lingual roots are seen from this aspect.

distobuccal is hidden behind the mesiobuccal.

lingual root appears long and slender and extends lingually.

It curves buccally at the apical third

Distal aspect

crown is narrower and shorter distally then mesially.

distobuccal cusp is long and sharp,

distolingual is poorly developed.The prominence of the cervical ridge seen from the mesial aspect at the cervical third

does not continue distally.

cervical line is similar to the distal or straight.

All three roots may be seen from this aspect,

but the distobuccal root is superimposed on the mesiobuccal

Prof Hanaa Aly


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Occlusal aspect DECIDUOUS MAXILLARY FIRST MOLAR

rectangular, with the shortest sides of the rectangle represented by the marginal ridges.

Usually have four cusps

but it may appear somewhat like maxillary premolars from

the occlusal view as there is two prominent cusps (a wide mesiobuccal cusp and a narrower mesiolingual cusp).

the distobuccal and distolingual are relatively indistinct.

Sometimes the distolingual is absent.

The occlusal surface has three fossae:

a medium-size central fossa, a large mesial and deep triangular fossa,

and a minute distal triangular fossa, each with a pit: central, mesial, and distal respectively .

A sulcus with its central developmental groove connects the central and mesial fossae.

There is also a buccal developmental groove extending from the central fossa between MB and DB cusps.

There are supplemental grooves radiating from the pit in the mesial triangular fossa.

These grooves radiate as follows:One buccally, one lingually and one toward the marginal ridge,

the last may extend over the marginal ridge mesially.

There will be either an oblique ridge connecting the mesiolingual cusp with the distobuccal cusp.

Or when this ridge is poorly developed, the central developmental groove extends from the mesial pit to DDG

This distal developmental groove is always seen and may or may not extend through to the lingual surface,

outlining a distolingual cusp.

The distal marginal ridge is thin and poorly developed than the mesial

Prof Hanaa Aly


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DECIDUOUS MAXILLARY SECOND MOLAR

resembles the 6-year permanent maxillary first molar

which erupts distal to it except that:

It is smaller in size.

The deciduous crown is more constricted at the cervix

= 6

with a more prominent cervical ridge buccally.

The roots are more slender and almost twice as long as the crown.

They flare out greatly at the middle and apical thirds.

The root trunk is almost absent

Prof Hanaa Aly


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Occlusal aspect

The outline of this tooth occlusally is rhomboidal.

The prominence mesiobuccally at the cervical third of the crown is noticed from this aspect.

DECIDUOUS MANDIBULAR FIRST MOLAR

The occlusal surface hasa central fossa with a central pit and a mesial triangular fossa,

just distal to the mesial marginal ridge with a mesial pit at its apex.

The central developmental groove extends between the central pit and the mesial pit

separating the mesiobuccal and the mesiolingual cusps.

The mesiolingual cusp is the largest and best developed of all cusps.

The buccal developmental groove extends buccally from the central pit,

equally dividing the mesiobuccal and distobuccal cusps.

Supplemental grooves radiate from the mesial pit buccally and lingually.

The lingual developmental groove extends lingually from the central pit,

separating the mesiolingual and the distolingual cusps.

Supplemental grooves radiate in the distal triangular fossa immediately mesial to the distal marginal ridge.

These grooves join the central developmental groove

Prof Hanaa Aly


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DECIDUOUS MANDIBULAR SECOND MOLAR

resembles the permanent mandibular first molar except for the following:

The deciduous molar is smaller in size

crown is more constricted at the cervix.mesiobuccal, distobuccal and distal cusps equal in size.

( distal cusp of permanent molar is smaller than the other two).

the deciduous tooth crown is narrower buccolingually in comparison

=6

w e mes o s a measuremen , an n e permanen mo ar.

The roots are more slender than those of the permanent molar

. They are also twice as long as the crown.

They flare out greatly and have a very short or no root trunk,

( a well developed root trunk is seen on the permanent molar)

Prof Hanaa Aly


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When the teeth in mandibular arch come into contact with these in maxillary arch in any functional relation

The maxillary arch is larger than the mandibular arch.

In centric occlusion: the buccal cusps and incisive edges of the upper teeth occlude outside or facial to those of the lower teeth.

The lower canines always occlude in front of or mesial to the upper canines.

In the stage of full development

the mesiobuccal cusps of the upper molars occlude outside but opposite the buccal groove between the mesiobuccal

and distobuccal cusps of the lower molars.

At the same time the mesiolingual cusps of the upper molars occlude with the central fossae of the corresponding

lower molars

each tooth, with the exception of the mandibular incisor and the maxillary last molar occludes with two teeth of the

opposite jaw.

A maxillary tooth occludes with the corresponding mandibular tooth and the one distal to it.

Prof Hanaa Aly


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DETAILS OF OCCLUSION OF THE

DECIDUOUS TEETH

Occlusion of the deciduous teeth is better described before the beginning of separation

i.e. in closed dentition.

The mesial surfaces of maxillary and mandibular central incisors are in line with each other at the median line

. The mandibular anterior teeth

occlude the maxillary anterior teeth lingually above the level of the incisal ridges.

The maxillary central incisor

occludes with the mandibular central incisor and the mesial third of the mandibular lateral incisor.

The maxillary lateral incisor occludes with the distal two- thirds of the mandibular

lateral incisor and the mesial slope of the mandibular canine.

The maxillary canine occludes with the distal slope of the mandibular canine and

the mesial third of the mandibular first molar mesial to the tip of the mesiobuccal cusp.

The maxillary first molar occludes with the distal two-thirds of the mandibular first molar

and the mesial 1/3 of the mandibular second molar (mesial marginal ridge and mesial triangular fossa).

The maxillary second molar occludes with the remainder of the mandibular second molar.

The distal surface of the maxillary molar projecting slightly over the distal portion of the mandibular second molar.

DISTAL STEP Prof Hanaa Aly


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Prof Hanaa Aly

deciduous teeth [compatibility mode]

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