Anatomy - Obj 6.1 - 6. (Week 3 PP) Flashcards
Anterior Permanent Dentition
- There are 12 anterior teeth in the permanent
dentition, six in each dental arch - The permanent anterior teeth include the central
incisors, lateral incisors, and canines - The central incisors are closest to the midline, the
lateral incisors are the second teeth from the
midline, and the canines are the third teeth from
the midline - All anterior teeth are succedaneous, replacing
primary teeth of the same type
Characteristics of Permanent Anterior Teeth
- All anterior teeth have a cingulum, a rounded,
raised area on the cervical third of the lingual
surface - The lingual surface on anterior teeth has rounded,
raised borders on the mesial and distal surfaces
called marginal ridges - Some anterior teeth have a fossa, which is a wide,
shallow depression on the lingual surfaces (Bird &
Robinson, 2021)
Permanent Incisors
- There are eight permanent incisors
◦ Four maxillary
◦ Four mandibular - The maxillary group comprises two central incisors
and two lateral incisors, as does the mandibular
group - These teeth complement each other in form and
function - The central incisors erupt about a year or so
before the lateral incisors do
Maxillary Central Incisors
Maxillary central incisors (1.1 and 2.1) have unique
anatomical features
* Larger in all dimensions, especially mesiodistally, than
a permanent mandibular central incisor
* Root is short compared with the roots of other
permanent maxillary teeth
* All lingual surface features, including the marginal
ridges, lingual fossa, and cingulum, are more
prominent on the maxillary central incisor than on the
mandibular central incisor
The incisal edge is also known as the incisal surface or incisal plane
* When newly erupted, the central and lateral
incisors have three mamelons, or rounded enamel
extensions on the incisal ridge, or edge
* The mamelons usually undergo attrition shortly
after eruption
Maxillary Lateral Incisors
The maxillary lateral incisors (1.2 and 2.2) are
smaller than the central incisors in all dimensions except root length
* They usually erupt after the maxillary central
incisors
* The crown of a maxillary lateral incisor has a single
root that is relatively smooth and straight but may
curve slightly distally
* Recognizing this feature is helpful in the mounting
of radiographs
The lateral incisors vary in form more than any
other tooth in the mouth, except the third molars,
and are often congenitally missing
* Because of the variations in form, the permanent
maxillary lateral incisors present challenges during
preventive, restorative, and orthodontic procedures
* Open contacts (spaces between teeth), called
diastema, often occur in this area because of the
variations in tooth size and position in the arch
Pegged Maxillary Lateral Incisor
“stump tooth”
Mandibular Incisors
- The permanent mandibular incisors are the
smallest teeth of the permanent dentition and the
most symmetric - The central and lateral incisors of the mandibular
arch resemble each other - Generally, the lateral incisor is larger than the
central incisor, in contrast to the teeth in the maxillary arch - Supragingival tooth deposits, such as plaque, calculus, and stain, tend to collect in the lingual concavity of the mandibular incisors
Mandibular Central Incisors
The mandibular central incisors (3.1 and 4.1) are
the smallest and simplest teeth and are bilaterally
symmetric
* Each has a small centered cingulum, subtle lingual
fossa, and equally subtle marginal ridges
* The crown of a mandibular central incisor is
narrower on the lingual surface than on the labial
surface
* Developmental horizontal lines on anterior teeth,
or imbrication lines, and developmental
depressions usually not present or very faint
Mandibular Lateral Incisors
The mandibular lateral incisors (3.2 and 4.2) are
slightly larger than the mandibular central incisors
but otherwise similar to them
* The lateral teeth usually erupt after the mandibular central incisors
* The lateral incisors have a small, distally placed
cingulum
* Greater height of the cementoenamel junction
(CEJ) curvature on the mesial surface than on the
distal surface helps distinguish the right
mandibular lateral incisor from the left incisor
Permanent Canines
- The permanent canines are the four anterior teeth
located at the corner of each quadrant for each
dental arch
The permanent canines are the longest teeth in
the dentition - The root is usually the length of the crown
- This large root is externally manifested by the
bony vertical ridge called the canine eminence
(Bird & Robinson, 2021)
Maxillary Canines
The maxillary canines (1.3 and 2.3) usually erupt
after the mandibular canines, after the maxillary
incisors, and possibly after the maxillary premolars
* The cusp tip is sharper on a maxillary canine
* The mesial cusp slope is usually shorter than the
distal cusp slope in both the maxillary and the
mandibular canines when they first erupt
* The length of these cusp slopes, and the cusp tip
can change with attrition
Mandibular Canines
The mandibular canines (3.3 and 4.3) usually erupt
before the maxillary canines and after most of the
incisors have erupted
* A mandibular canine closely resembles a maxillary
canine
* Although the entire tooth is usually as long, a
mandibular canine is narrower labiolingually and
mesiodistally than a maxillary canine
* The lingual surface of the crown of the mandibular
canines is smoother than that of the maxillary canines
and has a less developed cingulum and two marginal
ridges
Clinical Considerations with Canine s
The maxillary canines may erupt labially or
lingually in relation to the surrounding teeth
* The maxillary canines may also fail to erupt fully
and may remain impacted
* This occurs because the permanent maxillary
canines erupt after the maxillary incisors and
possibly after the premolars and their arch spaces
have closed
Posterior Permanent Dentition
The permanent posterior teeth include the
premolars and molars
* The crown of each posterior tooth has an occlusal
surface, bordered distally and mesially by marginal
ridges
* The occlusal surfaces have two or more cusps
* Imagine each cusp as a mountain with sloping
areas, or cusp ridges, extending from the top of
the mountain; between the ridges are sloping
areas called inclined cuspal planes
Each shallow, wide depression on the occlusal
table is a fossa
* One type of fossa on posterior teeth, the central
fossa, is located where the cusp ridges converge in
a central point, where the grooves meet
* Another type of fossa is the triangular fossa
* Sometimes located in the deepest portions of the
fossa are occlusal developmental pits
◦ Each pit is a sharp pinpoint depression where two or
more grooves meet
Permanent PreMolars
- There are eight premolars in the permanent
dentition, two in each quadrant - They are located posterior to the canines and
immediately anterior to the molars - There are two types of premolars
◦ First
◦ Second
Maxillary First Premolars
A maxillary first premolar (1.4 and 2.4) is larger
than a maxillary second premolar
* Each maxillary first premolar has two cusps
(buccal and lingual) and two roots (facial and
lingual)
* Both maxillary premolars erupt earlier than the
mandibular premolars
The maxillary first premolar has a bifurcated root
(two roots: one buccal and one lingual)
* Some first premolars have roots that are joined, or
fused
* The roots are shorter in length and resemble the
roots of the molars
Maxillary Second Pre-Molars
- Each maxillary second premolar (1.5 and 2.5) has
two cusps (buccal and lingual) and one root
Differences between Second and First Maxillary Premolars
- The cusps are closer in length on the second premolar
- The lingual cusp is slightly shorter, but not as short as
the cusp on the maxillary first premolar - The mesiobuccal cusp slope is shorter than the
distobuccal cusp slope on the second premolar - The cusps of the secondary premolar are not as sharp as
those of the maxillary first premolar - The second premolar has only one root and one root
canal - The second premolar is wider buccolingually than
mesiodistally
Mandibular First Premolars
Each mandibular first premolar (3.4 and 4.4) has a
long and well-formed buccal cusp and a small,
nonfunctioning lingual cusp
* The lingual cusp may be no larger than the
cingulum on some maxillary canines
* The mandibular first premolars are smaller and
shorter than the mandibular second premolars
Mandibular Second Premolars
- The permanent mandibular second premolars (3.5
and 4.5) erupt distal to the mandibular first
premolars - They are the succedaneous replacements for the
primary mandibular second molars - There are two forms of the mandibular second
premolar
◦ Three-cusp type, or tricuspidate form
◦ Two-cusp type, or bicuspidate form (Bird & Robinson,
2021)
Mandibular Second Premolar Groove Types
“U” Type
“H” Type
“Y” Type
Clinical Considerations with PreMolars
The maxillary and mandibular premolars work
with the molars in the chewing of food
* The first premolars help the canines in shearing or
cutting bits of food
* The premolars also support the corners of the
mouth and cheeks
Permanent Molars
There are 12 molars, three in each quadrant, in
the permanent dentition
* The molar crowns have four or five short, blunt
cusps, and each molar has two or three roots that
help support the larger crown
There are three types of molars: First, second, and
third
* The first and second molars are also called the 6-
year and 12-year molars because of the
approximate ages at which they erupt
Maxillary Molars
- Usually, the first permanent teeth to erupt into
the maxillary arch - Each maxillary molar usually has four major cusps,
with two on the buccal portion of the occlusal
table and two on the lingual - Each maxillary molar has three well-separated and
well-developed roots - A tooth with three roots is said to be trifurcated,
which means “divided into thirds”