Dental Anatomy of Mandibular Incisors permanent teeth

PERMANENT MANDIBULAR

INCISORSDr.Najdalizade

MANDIBULAR INCISORMandibular central incisor and lateral are similar in anatomy and complement each other in function.The most simple teeth in shapeSmallest teeth permanentCentral a little smaller than the Latral, Unlike the Maxillary IncisorCrowm is a little larger than Maxillary Incisor in incisocervical and Narrow in

mesiodistal

MANDIBULAR CENTRAL INCISOR Mandibular central incisors are two in number

First tooth from the midline in each lower quadrant

bite and cutting

Mesial conatact with each other and distal contact with latral incisor

They are smaller than the maxillary central incisors

erupts at the 7

Narrowest tooth mesiodistally of all permanent teeth

TOOTH NUMBERING SYSTEMS Universal system24-25

Palmer

1 1

FDI3 1 – 4 1

3141

3.0 2.0 5.3 6.0 3.5 5.0 12.5 9.0

Curvature of Cervical Line M D

LabiolingualDiameter atCervical Line

LabiolingualDiameter atCrest of Curvature

MesiodistalDiameter atCervical Line

MesiodistalDiameter atContact Area

RootLength

Crown Length

Average Dimensions in millimeters

LABIAL ASPECT

The Labial surface is Convex in both Mesiodistal and Incisocervical

The H.OFC and max Convex of This surface is in cervical third

Reverse trapezoid Like rectangular

CEJ

LABIAL ASPECT

Mamelons are usually present on newly emerged teeth

3 Mamelons (like Maxilary incisor)

LABIAL ASPECT

The mesial and distal outlines is straight in the incisal third

The crown tapers to the cervical third

Contacts are well within the incisal one third

LABIAL ASPECT

Mesio and distoincisal angle is nearly 90 degrees

Mesioincisal Sharp than other incisor angle

It is the only incisor where both mesioincisal and distoincisal angles are sharp and at right angles

LABIAL ASPECT

Distoincisal angle may be more rounded than the mesioincisal angle

LABIAL ASPECT

The tooth is so symmetrical it is difficult to tell left from right

Only difference is the mesial cervical line curve more incisally than the distal

LABIAL ASPECT

H.OFC is in the incisal third and it’s in contact area

Mesial and distal contact areas are within the incisal third at roughly the same height and it’s near to incisal edge

LABIAL ASPECT

Can have two shallow depressions in the incisal third (similar to maxillary, but far less pronounced)

It’s from incisal edge to cervical third

No Imbrication Line

LINGUAL ASPECT

Mesial contour is like labial surface but som time it’s concave in gingival semi

Distal contour is like labial surface

The Crown incisocervical length is more than labial surface And CEJ is Closer to Apex

No grooves, pits or accessory ridges are present

Marginal ridge

Mesilingual and distolingual Primery Depression seen sometimesin insical part

CEJ

LINGUAL ASPECT

The lingual crown surface is smooth and shallow witha slight concavity in the middle and incisal thirds

The cingulum is convex, small and centered

H.OFC is cingulum

PROXIMAL ASPECT triangle

The labial contour is so slightly curved than cervical third

The lingual contour is convex on the cingulum(1/3), concave in the fossa(2/3)

The lingual margin is ‘S’ shaped

The cervical line on the mesial and distal surface is convex incisally

CEJ in distal Surface have lower arch

‘S’ shaped lingual surface

Cervical line convex incisally

PROXIMAL ASPECT

The facial height of contour is located in the cervical third

The lingual height of contour is located on the cingulum, within the cervical third

Contact area is in center and in incisial third and it’s oval

PROXIMAL ASPECT

The incisal edge is on or lingual to the long axis of the root

The slope of the incisal edge is to Lingual(occlusion)

INCISAL ASPECT

The labiolingual measurement of the crown is greater than the mesiodistal measurement

rhombic(Unlike maxilary)

bilateral symmetry (Unlike maxilary)

The incisal edge or ridge is at right angles to the labiolingual root axis plane(Unlike maxilary)

Cingulum have veryfaint tendency to distal

ROOT The root is single and straight

From labial or lingual view, root is generally symmetricalt,Root and tapers gradually to a relatively sharp apex

tip may curve to the distal

wide faciolingually

Root is narrow mesiodistally, tapering gradually fromthe cervical line to the apex

The facial and lingual sides of theroot are nearly straight from the cervical line to the middle third

Longitudinal grove and …

cross section in CEJ and Mid

ROOT

In cross section at neck, outline is roughly a rectanglewith rounded corners, but it is slightly wider at labial than at lingual

When there are root concavities present, they are reflectedas concavities in the mesial and distal outlines

The mid root cross section is similar to the cervical section,only more ovoid

ROOT SECTION

VARIATIONS AND ANOMALIES: Anomalies are rare, but occasionally a bifurcated root is found

MANDIBULAR LATRAL INCISOR Mandibular latral incisors are two in number

Second tooth from the midline in each lower quadrant

bite and cutting and complements the central in function

Mesial conatact with Central Incisor and distal contact with Canine

slightly wider mesiodistally

Bilateral symmetry not seen

erupts at the 8

slightly larger in all respects than the mandibular central incisor

TOOTH NUMBERING SYSTEMS Universal system23-26

Palmer

2 2

FDI3 2 – 4 2

3.0 2.0 5.8 6.5 4.0 5.5 14.0 9.5

Curvature of Cervical Line M D

LabiolingualDiameter atCervical Line

LabiolingualDiameter atCrest of Curvature

MesiodistalDiameter atCervical Line

MesiodistalDiameter atContact Area

RootLength

Crown Length

Average Dimensions in millimeters

Labial aspect Lingual aspect Mesial aspect Distal aspect

Incisal aspect

LABIAL ASPECT

The Labial surface is Convex in both Mesiodistal and Incisocervical

The H.OFC and max Convex of This surface is in cervical third

Reverse trapezoid Like rectangular

CEJ

minimal depressions

LABIAL ASPECT

Mamelons are usually present on newly emerged teeth

3 Mamelons (like Maxilary incisor)

LABIAL ASPECT The cervical portion of the lingual aspect is narrower while theincisal portion is wider. This gives the crown a more or less a fanshaped appearance

The crown tapers to the cervical third

Contacts are well within the incisal one third

Mesial and distal contact areas are within the incisal third but not at roughly the same height and The distal contactcervical to the level of the mesial contact

H.OFC is in the incisal third and it’s in contact area

Contact area on distal is more cervically located than onThe mesial, thus creating a more cervically located height ofcontour on distal outline

Incisal margin may slope slightly gingivally toward distal,which results in a distoincisal angle that is more rounded than same angle of central incisor

This feature creates a slightly shorter distal margin, when compared to mesial outline

LABIAL ASPECT

LABIAL ASPECT

Can have two shallow depressions in the incisal third (similar to maxillary, but far less pronounced)

It’s from incisal edge to cervical third

minimal depressions(central)

No Imbrication Line

LINGUAL ASPECT not bilaterally symmetrical

Crown is tilted distally

Mesial contour is like labial surface

Distal contour is like labial surface

The Crown incisocervical length is more than labial surface And CEJ is Closer to Apex

No grooves, pits or accessory ridges are present

Marginal ridge

Mesilingual and distolingual Primery Depression seen sometimesin insical part

CEJ

LINGUAL ASPECT

The lingual crown surface is smooth and shallow witha slight concavity in the middle and incisal thirds

The cingulum is slightly distal to the long axis of the root,similar to the maxillary central

This makes the mesial marginal ridge longer than the distal

The cingulum is convex, small and centered

H.OFC is cingulum

Marginal ridges and lingual fossa are not conspicuous and generally smooth

Mand. Lat. InciosorMand. Central Incisor

M D D M

PROXIMAL ASPECT triangle

The labial outline in the incisal third is slightly convex andin the middle and incisal thirds is nearly flat

The lingual contour is convex on the cingulum(1/3), concave in the fossa(2/3)

The lingual margin is ‘S’ shaped

The cervical line on the mesial and distal surface is convex incisally

Both cervical line curvatures are slightly less than theircounterparts in the central.

CEJ in distal Surface have lower arch

‘S’ shaped lingual surface

Cervical line convex incisally Central Lateral

PROXIMAL ASPECT

The facial height of contour is located in the cervical third

The lingual height of contour is located on the cingulum, within the cervical third

mesial Contact area (H.ofc) is in center(labioligual) and inIncisial third and it’s oval

Distal Contact area (H.ofc) is in central but in incisial andmedial third(only)

PROXIMAL ASPECT

The incisal edge is on or lingual to the long axis of the root

The slope of the incisal edge is to Lingual(occlusion)

From the mesial a distolingual twist of the incisal edge places the distal portion more lingual

Central Lateral

INCISAL ASPECT

The labiolingual measurement of the crown is greater than the mesiodistal measurement

Not bilaterally symmetrical, distal is twisted (Unlike central)

The cingulum is off center to the distal

ROOT The root is single and straight

Root length is normally a little greater than in central incisor

Root is also slightly thicker and wider

Not symmetricalt,Root and tapers gradually to a relatively sharp apex

tip may curve to the distal

wide faciolingually

Root is narrow mesiodistally, tapering gradually fromthe cervical line to the apex.It may have a distal curvature

The facial and lingual sides of theroot are nearly straight from the cervical line to the middle third

Longitudinal(distal>mesial) grove and …

Root concavities may be found on the mesial anddistal root surfaces, and if present, concavity in distal is usually more pronounced

cross section in CEJ and Mid

ROOT

In cross section at neck, outline is roughly a rectanglewith rounded corners, but it is slightly wider at labial than at lingual

When there are root concavities present, they are reflectedas concavities in the mesial and distal outlines

The mid root cross section is similar to the cervical section,only more ovoid

ROOT SECTION

VARIATIONS AND ANOMALIES: Anomalies are rare, but occasionally a bifurcated root is found

MANDIBULAR CENTRAL INCISOR MANDIBULAR LATERAL INCISOR

1. CROWN MORE SYMMETRICAL LESS SYMMETRICAL

2. CROWN & ROOT ARE SHORTER CROWN & ROOT ARE LONGER

3. CINGULUM CENTERED CINGULUM DISTAL TO CENTRE

4. NO DISTOLINGUAL TWIST OF INCISAL EDGE

DISTOLINGUAL TWIST OF INCISAL EDGE

5. MARGINAL RIDGES NOT PROMINENT LONGER MESIAL MARGINAL RIDGE

MAXILLARY INCISORS MANDIBULAR INCISORSLABIAL1. CROWN MESIODISTALLY WIDER & LESS

SYMMETRICALCROWN IS LONG, NARROW & MORE SYMMETRICAL

2. DISTOINCISAL ANGLES MORE ROUNDED MESIOINCISAL SHARP, & DISTOINCISAL ANGLES ARE SLIGHTLY ROUNDED

3. SHALLOW LABIAL DEPRESSIONS ARE COMMONLY PRESENT

NOT PRESENT

LINGUAL1. LARGER CINGULUM SMALLER CINGULUM2. DEEPER LINGUAL FOSSA SHALLOW FOSSA3. SOMETIMES LINGUAL PITS PRESENT LINGUAL PITS ABSENT

4. PROMINENT MARGINAL RIDGES LINGUAL SURFACE SMOOTH, less MARGINAL RIDGES

5 CINGULUM SLIGHTLY DISTAL CENTRAL ALMOST SYMMETRICALPROXIMAL1. CINGULUM IS PROMINENT VERY SMALL CINGULUM2. INCISAL EDGE LABIAL TO ROOT AXIS INCISAL EDGE LINGUAL TO ROOT AXIS

INCISAL

1. CROWNS ARE WIDER MESIODISTALLY THAN FACILINGUALLY

CROWNS WIDER FACIOLINGUALLY THAN MESIODISTALLY

2. INCISAL EDGE LABIAL TO ROOT AXIS INCISAL EDGE LINGUAL TO ROOT AXIS

3. CINGULUM OF CI IS SLIGHTLY DISTALCINGULUM OF LI IS IN CENTRE

CINGULUM OF CI IS CENTEREDCINGULUM OF LI IS SLIGHTLY DISTAL

4. LABIAL SURFACE OF LI IS SLIGHTLY CONVEX CENTRAL & LATERALS HAVE ALMOST FLAT LABIAL SURFACES AT INCISAL & MIDDLE 3rd.

REFERENCESCONCISE DENTAL ANATOMY & MORPHOLOGY : JAMES L FULLER

DENTAL ANATOMY, PHYSIOLOGY & OCCLUSION: WHEELER’S