maxillary lateral incisor

how many lateral incisors are there? which tooth is it from the midline?

two in the maxillary arch and two in the mandibular arch. it is the second tooth from the midline

what is the functions of the lateral incisor?

• its functions in mastication are:

  • biting

  • cutting

  • incising

  • shearing

• play an important role in

  • aesthetics

  • phonetics

what is the general form of the lateral incisor?

• supplements the central incisor in function

• resembles the central incisor in all aspects but on a smaller scale

the lateral incisor is smaller in all aspects but what? how else does it differ?

• it is smaller in all measurements but root length, which is roughly the same

• its relative crown dimensions, hence its shape, differ slightly from the central incisor. it is relatively longer inciso-cervically and narrower mesiodistally. it is also generally more of a round tooth than the central incisor

the upper lateral incisor displays what?

greater variation in form than any other permanent tooth, except for the third molars

when is the first appearance of the dental organ of upper lateral incisors?

5 m.i.u (months in utero)

when is the first evidence of calcification?

1 year

when is the enamel completed in upper lateral incisors?

4-5 years

when do upper permanent lateral incisors erupt?

8-9 years

when is the root completed?

11 years

how is the upper lateral incisor named in the different systems?

palmar system

• 2」∟2

universal system

• #7, #10

FDI

• 12, 22

relation of lateral incisors

• they make contact mesially with the distal surface of the maxillary permanent central incisors

• they make contact distally temporarily with the mesial surface of the maxillary deciduous canine until it’s shedding at 12 years, then erupts the maxillary permanent canine

what are the surfaces and aspects of the lateral incisors? how many roots does it contain?

its surfaces are:

• labial

• lingual

• mesial

• distal

it contains one root

• it has an incisal aspect

what is the geometrical outline of the crown at the labial aspect?

• it is a trapezoid, long side is incisally and short side is cervically

the mesial outline at the labial aspect is what?

• it is slightly convex at the crest of the junction of the incisal and middle thirds

which outline is more convex at the labial aspect? the incisal outline is more curved than what? the cervical line is convex in what direction?

• the distal line is more convex

• the incisal outline is more curved than the central incisor’s

• the cervical line is convex root-wards

which incisal angle is more rounded?

• mesio-incisal angle is rounded, but the disto-incisal angle is more rounded

is the surface of the lateral incisor more convex or concave than the central incisor?

it is more convex than the central incisor

the red circle is what?

the cervical ridge, which is located the cervical 1/3

how many roots does the lateral incisor contain? what are its characteristics at the labial aspect?

one root, which tapers evenly to the apical 1/3. it then curves distally with a pointed apex

palatal / lingual aspect of maxillary upper lateral incisor

• contains the same geometrical outline and outline as the labial surface

why do the mesial and distal sides of the crown and root converge lingually?

due to lingual convergence, which is to accommodate the horseshoe shaped alveolar process, making it narrower and smaller than the labial surface

the pink circle is what elevation?

the cingulum (present at cervical 1/3)

the pink arrows parallel to each other are what elevations?

the mesial and distal marginal ridges

the rounded arrow is what elevation?

the incisal ridge

the green circle is what depression?

the lingual fossa, which lies between all the previous elevations. lingual pit is present between it and the cingulum

all elevations and depressions are more developed in what tooth?

it is more developed in the lateral incisor than the central incisor

geometrical outline of the crown at the mesial aspect

• triangular in shape. base cervically and the apex incisally

• incisal ridge is on the line that bisects the center of the root

labial outline of mesial aspect of lateral incisor

convex at cervical 1/3 (cervical ridge), which then becomes slightly convex to the incisal ridge

lingual outline of mesial aspect of lateral incisor

convex at cingulum (cervical 1/3), then it becomes concave at the lingual fossa, then slightly convex at the incisal ridge

the mesial cervicale line is convex where?

it is convex incisally

what is the labiolingual measurement of the lateral incisor?

about 6.0-6.5 mm, which is about 1mm less than the central incisor (6.5-7.0 mm)

the red dot represents what?

the mesial surface is convex with the maximum convexity at the junction of the incisal and middle 1/3 (the contact area)

characteristics of root in mesial aspect

• root appears longer than central incisor

• it is cone shaped with blunt apex

distal aspect of lateral incisor

similar to the mesial aspect but differ in:

• the cervical line curvature is less than the mesials by 1mm (mesial: 2.5 mm, distal: 1.5 mm)

the red dot represents what? what is highlighted in blue?

• contact area is the red dot, which is located at the middle 1/3 (more cervically)

• highlight in blue is the distal developmental groove on the root

incisal aspect of lateral incisor

• may resemble the central incisor or small canine

what dimension is greater?

• labiolingual dimension is greater in comparison to the central incisor

• cingulum is large and large incisal ridge is present

the incisal surface of the lateral incisor generally resembles the central incisor except for what? how else does it differ?

• except for the cingulum, which is more prominent than the central incisor

• it also exhibits more convexity labially and lingually than the central incisor and its outline may approach the rhomboidal appearance of the canine

what shape should the maxillary lateral incisor be for root canals?

a triangle, with base at incisal edge and the apex at cervical line

what is the average, minimum, maximum and range length of the tooth?

• average: 32

• maximum: 25.1

• minimum: 20.5

• range: 4.6

what is the percentage for one canal vs. two canals?

• one canal: 93.4%

• two canals 6.6%

meaning type 1 is most common

what is percentage for lateral canals?

10%

root curvature percentages?

• straight: 30%

• distal curved: 53%

• mesial curved: 3%

• labial curved: 4%

• bayonet and gradual curve: 6%

mesio-distal section of pulp cavity

• pulp chamber is wide and conforms to the shape of the crown

• it does not have 3 sharp pulp horns, it contains 2, which correspond to the developmental mammelons

• the root canal tapers towards the apex

labiolingual section of pulp cavity

• pulp chamber is pointed incisally, which then follows the increase in the crown dimension cervically

• the root canal tapers gradually as it traverses the root ending in a constriction at the apex (apical foramen)

what is the shape of the tooth cross-sectioned?

• cervical level: canal is ovoid labiopalatally

• middle third level: canal is ovoid

• apical third level: apical is generally round in shape

what are some malformations of the upper permanent lateral incisor?

• peg-shaped lateral incisor

• missing lateral incisor