Deciduous teeth are that teeth which function during childhood and then they are shed and replaced by permanent teeth. The word deciduous comes from a Latin word meaning to fall off.

There are 20 teeth in the deciduous dentition; 10 maxillary and 10 mandibular teeth.

These teeth emerge in children between the ages of 6 months and 2 years

Beginning at the age of 6 years these teeth are gradually replaced by the teeth of the permanent dentition.

Names: Temporary teeth, milk teeth, baby teeth. Primary teeth, all are improper terms because they means that deciduous teeth are useful for a short period only.Importance of deciduous teeth a-They need for many years from 6month to 12 years. b-They are importance during growth and development for proper arrangement of the permanent teeth and proper development of the dental arches.Avoid premature loss of deciduous teeth.

Eruption of the deciduous teeth Start from 6month to

2years and root completed at 3years.

6m

7m

16m

12m

20m

24m

14m

18m

8m

7m

Shedding of the deciduous teeth Shedding is the process of exfoliation of the

deciduous teeth. Shedding dates: Upper and lower central incisors at 7years. Upper and lower lateral incisors 8y. Lower canine and first molar 9y. Upper molar and lower second molar at 10y. Upper canine 11y. Roots resorped first at the apex and continues in

the direction of the crown until the entire root is resorped completely then crown is lost due to lack of support.

From 6m to 6y deciduous dentition.From 6y to 12y mixed dentition.Over 12 years permanent dentition. Retained deciduous tooth:Any deciduous tooth remain in the mouth of the child beyond the age of 12 years.

Smaller in size than the permanent teeth.The enamel is whiter in color and more

opaque which gives the crown a lighter color than that of the permanent teeth.

The enamel of the deciduous teeth is less mineralized, more permeable and more easily worn down.

They have shorter crowns with respect to their roots.

The enamel of deciduous teeth ends suddenly at the cervical line, while in the permanent it tapers gradually towered the neck of the teeth.

*The crowns are more bulbous, because they are wider MD compared to their crown length.*The crown of deciduous teeth are more constricted cervically as they are narrower at their neck.*The crown of deciduous teeth have prominent cervical ridge in anterior teeth (ABC) in posterior teeth cervical ridge much more pronounced especially upper and lower D. The crown of the deciduous teeth have more flattened and smooth no depression or perikymata on the labial surface of anterior teeth.

* Cervical line in deciduous teeth is more or less straight not curved as in permanent teeth.*There is no root trunk, root divided immediately at the neck of the tooth.

Roots of molars are more divergent to accommodate tooth germ of permanent successors.

Crown to root ratio is greater than permanent 1 to 2 while in permanent 1 to 1.5.

Roots are thin or slender. The second molar roots are spread widely than the

first deciduous molar. All deciduous teeth undergo calcification before

birth while only the first permanent molar show calcification at birth.

There is no mamelones on the incisal edges of anterior teeth.

The molar crown have a narrow chewing surface buccolingually.

The cusps of the molars are short, the ridges are not pronounced and also the occlusal and surfaces groove and depressions not deep.

The pulp of deciduous teeth

Deciduous teeth have large pulp chamber, higher pulp horn, limited dentine thickness particularly in lower second molar.

The enamel of primary molars is thinner and has more consistent depth.

The enamel rods at the cevical slope occlusally instead of gingivally as in the permanent teeth.

(a) labial surface is convex ,no developmental lines, MD width greater than CI length. MI angle is sharp and DI angle is rounded. IR is straight. Root is cone shape and taper to the apex.

(b) crown smaller than (a) ,CI greater than MD,2 angles are rounded. Root similar to A but longer.

M slope greater than D slope, MCA and DCA at the same level about middle of the crown .Well developed long and sharp cusp .Neck more constricted . M and D outline are convex .Root is long slender tapering and inclined distally.

Constricted neck

Sharp cusp

(a) geometric outline is trapezoid. Well developed M&DMR, deep lingual fossa, highly developed cingulum may extend toward the incisal ridge to the extent that partially divides the lingual fossa into mesial and distal fossa. Root is very narrow resembling a ridge extends for its whole length.

(b) smaller than (a). (c) pronounced cingulum, pronounced M&DMR ,pronounced

DIC&MIC ridges ,lingual ridge well developed its continuation incisally give tubercle on cusp tip. Root is narrow lingually due to the lingual convergence.

MMR

DMR

LF

LR

2L fossae

(a) geometric outline is triangular . C.L is convex toward the incisal ridge. Labiolingual dimension greater in compared to the crown length especially at cervical third. Also crown appear thick labiolingually in the cervical and middle third. Root is convex and has deep DG or concavity.

(b) similar to (a). (c) show much greater labiolingual dimension at cervical

third. Root is very long. This allows maximum strength to the canine to resist force applied on it during function.

Root convex with DG

CL convex toward IR

Greater Labiolingual

(a) labiolingual greater than MD. Labial surface broad & smooth, lingual surface tapers toward the cingulum, M&D surfaces relatively broad to allow proper C.A. with adjacent teeth. IR is straight and centered labiolingually.

(b) similar to (a) but it smaller. (c) crown appear diamond with pronounced

cervical ridge, MCA&DCA and cingulum. The cusp tip is distal to the center because M slope longer than D slope.

(d) labial surface is flat and has no DG. M&D sides tapers from C.A. to a narrow cervix. Root long and tapers to pointed apex.

(e) similar to (d) but it is larger in all dimension. IR sloped toward distal side so the distal contact area more cervically.

(f) M slope shorter than D slope.

MD

(d) lower central incisor, all elevations are well developed. Lingual fossa is flattened or slightly concave at the middle third of the crown. Crown and root is narrower than labial due to the lingual convergence.

(e) lower lateral incisor, lingual fossa more concave than lower central incisor lower central incisor (d). Cingulum more developed than lower central incisor (d). IR slope downward D.

(f) lower canine similar to upper deciduous canine.

(d) lower central incisor no lingual inclination, IR is centered over the axis of the root. Well developed cervical ridge and cingulum. Root is flat and tapers to blunt apex.

(e) lower lateral incisor lingual inclination, C.R. and cingulum less developed.

(c) lower canine similar to upper canine but C.R. and cingulum less developed.

A lower central incisor, incisal ridge is straight and centered labiolingually. Labial surface is flat or slightly convex. Also lingual surface is flat.

B lower lateral incisor, incisal ridge is inclined toward the distal side.

C lower canine crown appear diamond . All ridges less prominent than upper canine. The lingual ridge is raised in the incisal third & then less distinct .

AB C

Mandibular lower central deciduous incisor

Labial aspect Lingual aspect Mesial aspect Distal aspect

Mandibular lower lateral deciduous incisor

labial lingual Mesial Distal

Mandibular lower deciduous canine

Labial

Lingual

Mesial

Distal

Maxillary first & second deciduous molars

Maxillary second molar

Maxillary first molar

Buccal aspects of upper deciduous molars

Upper D (a): geometric outline of the crown is trapezoid. Buccal surface is very smooth with little evidence of developmental groove Occlusal outline has a slightly scalloped appearance with no definite cusp

form. There is mesio-buccal cervical ridge (MBCR) 3Roots are seen MBR, DBR & LR Upper E (b):. Geometric outline of the crown is trapezoid. Crown converge markedly from the contact area to the cervical line. MBC equal DBC or MBC larger than DBC. 3Roots are seen MBR,DBR& LR. Roots are thicker than D The roots of both molars are divergent ,long &slender ,no root trunk.

Upper (D)Upper (E)

Occ. outline slightly scalloped

MBCR

Well developed cusps

Lingual aspects of upper deciduous molars

D Crown converge lingually. MLC largest &sharpest cusps. DLC is very poorly defined small and round. MMR is prominent. DBC is larger and better developed than DLC so may be seen. D may be 3- cusped type one lingual cusp with no developmental groove.

E MLC is long & well developed. DLC less developed. Tubercle of carabelli is seen related to MLC.

Upper (D) Upper (E)

MLC DLC

MMRMLC DLC

Tubercle of carabelli

Lingual narrower than buccal

Trapezoid outline

Mesial aspects of upper deciduous molars

D Crown is constricted at the occlusal 1/3 than cervically. Crown has pronounced cervical ridge buccally (MBCR). C.L.

shows slight curvature occlusally. Roots MBR, LR . The DBR hidden by MBR. E crown is o.5 mm longer than D. B-L dimension is 1.5-2 mm longer than D . Roots are 1.5-2 mm longer than D. Cervical line almost straight

line. MBR is broad & flat. LR is extend lingually beyond crown outline, It is long&

slender& it is above middle 1/3 curves buccally.

Upper (D)Upper (E)

MBCR

MBR

LRM

BR

LR

Board& flatOutline form is trapezoid with the shortest of uneven sides is occlusally.

Distal aspects of upper deciduous molars

D Crown converge distally (narrow than mesially). Cervical ridge is not so marked as mesially. Cervical line is straight or slightly curved occlusally.

E also it is narrower distally than mesially. The lingual outline appears semicircular, while the buccal outline is straight.

DB&DL cusps are about the same length. Cervical outline is straight. All three roots seen from this aspect. The point of bifurcation between DB& L roots is higher towered the crown than any other aspects.

LR

LR

DBR

MBR

Bifurcation at lower level

C L straight

DLC

DBC

DBR

MBR

DBC

DLC

Poorly developed

Long& sharp

MLC Lingual outline is semicircular

Buccal outline is straight

Occlusal aspects of upper D

Rectangular

Rectangular with oblique ridge

Heart shape

HexagonalBC

LC

MBC

MLC

DBC

DLC

B

D

L

MD

B

L

MD

B

L

LC

MBCDBC

MBC

OR

DBC

MLCDLC3Supplemental groove

Distal occlusal groove

MBCR

MBCR

M

Occlusal aspects of deciduous upper molars

D the occlusal surface is rectangular. The crown converge lingually & distally. The occlusal surface presented , CF&MTF the two fossae are connected by

central developmental groove. Central pit in the central of the center fossa from it extended B groove. Mesial

pit in the MTF give three grooves one buccally, one lingually & one mesial. Oblique ridge found between ML&DB cusps. If there is no oblique ridge central

developmental groove extend from mesial pit & give disto-occlusal groove . Disto-occlusal groove give lingual groove between ML&DL cusps.

E The occlusal surface is rhomboidal, has 4 well developed cusps & small fifth cusp.

Oblique ridge between ML&DB cusps. Central fossa, MTF,DTF, BG,LG,CG. The occlusal surface resemble the occlusal surface of upper 6

Mandibular first deciduous molar

This teeth does not resemble any of the other teeth either deciduous or permanent .It appears strange and primitive.

The second deciduous molar

It resembles the first permanent molar (lower 6) but it is smaller in size.

Buccal aspects of lower deciduous molar

D : geometric outline is trapezoid Mesiobuccal cusp is longer than

distobuccal cusp. As in upper D mesiobuccal cervical ridge

is prominent (MBCR) makes the cervical line dips downward to outline this shape.

There are two roots MR&DR. E: geometric outline is trapezoid, the

small of uneven side cervically. 3 buccal cusps are equal in size

MBC=BC=DBC. Two roots MR&DR, they are long,

slender & diverge M-D at middle and apical 1/3. No root trunk.

E D

M. outline is straight

Distal outline is converge markedly to the C.L.

MBCDBC

MBCR

DD

MBCBCDBC

Long, slender& diverge roots

Lingual aspects of lower deciduous lower molars D crown and root converge

lingually. MLC is long and sharp. DLC is well developed and

rounded. MMR is well developed

(regarded as third lingual cusp).

E crown and root converge lingually.

MLC=DLC Parts of 3 B cusps may be

seen. Mesial part of the crown is

longer than distal part.

DE

MLC long& sharp DLC rounded

MMR

MLC DLC

Mesial aspects of deciduous lower molars Geometric outline is rhomboidal. D buccal outline is flat above the

convex of the MBCR. It is longer than lingual outline (cervical line extends upward in B-L direction)

The lingual outline extends out lingually beyond the confines of root base.

MBC is placed over the root base. Root apex is flat and almost square. E: MLC is longer than MBC. Compared to lower 6 the cervical ridge

is prominent in lower E & it more constricted occlusally( due to the flatting of the buccal outline above the cervical line to buccal cusp tip).

M root is broad ,flat & blunt apex sometimes serrated apex.

D E

M root

Flat

MBCR

MBCMLC

Root apex is flat & almost square

Deep DG

MLC longer

MBC

Broad& flat

Serrated

Distal aspects of lower first deciduous molar D: distal aspect differs from

mesial aspect: 1-crown has an equal length

B&L. 2-DBC&DLC are not so long

and sharp as MBC&MLC. 3-DMR is less developed than

MMR. 4-B outline less curved at the

cervical 1/3 . 5-C.L. is straight. 6-Distal root is shorter, more

rounded, taper more in its apical third.

D root

DBCDLC

MBCMLCDMR

M root

Distal aspects of lower second deciduous molar

E: distal aspect differs from distal aspect:

1- Distal surface is narrower than mesial surface MBC&MLC are seen ,also the DLC well developed.

2- DMR is shorter &at lower level than MMR.

3- Distal root tapers more at the apical third.

DBCBC

MBCMLC

DLC

DMR

D root

M root

Occlusal aspects of lower deciduous molars

D : occlusal aspect is rhomboidal in shape. E: occlusal aspect is rectangular in shape. MD dimension at the buccal side larger than MD dimension

at the lingual side so the crown converge lingually. Also the crown converge distally . DTF not so well defined as mesial fossa. DMR is not as highly developed as mesial marginal ridge.

Rhomboidal outline Rectangular

outline

Buccal

Lingual

Mesial Distal

Buccal Lingual

Mesial

Distal