Dental Anatomy Part 2

Lobes

Primary growth centers/separate divisions that come together to form a tooth

On molars, what can lobes come together to form?

Cusps

All teeth are formed from how many lobes?

4-5

Mamelons

3 bulges on the incisal edge of newly erupted central incisors

3 rounded protuberances

Mamelons form from...

3 labial lobes

Perikymata

Small wave like ripples of enamel on newly erupted permanent teeth

Is perikymata seen on primary or permanent teeth?

permanent newly erupted

Cervical ridge

Bulge in the gingival third of the facial surface of an Anatomic crown

Where are cervical ridges found?

Mesiobuccal cusp of mandibular second molars

Common cervical ridge location

MB cusp of mandibular second molars

Crown depressions

Fossae

Pits

Primary grooves (developmental grooves)

Secondary grooves (supplemental grooves)

Analogy:

Mountain peak = cusp tip

Mountain ridge = cusp ridge

Valley = occlusal sulcus

Dried river bed = groove

Where river beds converge and there is a possible depression = fossa

Fossae

A rounded depression on the crown surface of a teeth

Occlusal surfaces of posterior teeth typically have how many deeper fossae?

2 or more

3 cusped pre-molars and most molars have how many fossae?

3

Mesial, central, distal

Incisors have a broad, shallow fossa where?

On the lingual side

Pit

A small depressed area where grooves join

A pit is where _________ join

grooves

Where are pits located?

Deepest part of the fossa

Occlusal sulcus

The broad V-shaped depression or valley on the occlusal surface of each posterior teeth running mesiodistally between the buccal and lingual cusps

Developmental (primary) groove

A groove that represents the coalescence of the lobes of the crown of the tooth

3 cusped premolars and most molars have how many fossae?

3

2 cusped premolars have how many fossae?

2

Central grooves are positioned...

Mesiodistally

How are major grooves named?

For the surface or line angle they "aim" towards

Other names for major grooves

Developmental/primary groove

Fossa developmental groove

located at ends of central groove and named for corner of tooth toward which they aim

Supplemental (secondary) groove

An auxiliary groove that branches from a developmental groove

How do supplemental grooves differ from primary grooves?

They generally are not as deep as primary grooves

Where are supplemental grooves located?

Branching from primary grooves

Secondary grooves are not related to...

Coalescence of tooth lobes

Where are oblique ridges found?

only on maxillary molars

Examples of secondary grooves

triangular grooves, marginal grooves

Embrasure

spaces present when two adjacent teeth contact each other

4 types of embrasure

Gingival (cervical), incisal/occlusal, facial, lingual

Lingual embrasure is ____________ than facial embrasure

Larger

The gingival embrasure is also called the

interproximal space that is filled with gingiva

Proximal contact area

The area where each tooth touches the adjacent tooth

As a general rule, contacts move more ______________ from anterior to posterior

Cervically

Anterior contacts are centered...

Faciolingually

Posterior contacts are located towards...

The Buccal of center faciolingually

Proximal contact areas move more ______________ positioned as you move distally from the midline

Gingivally

Proximal contact areas are centered ___________ at the midline (8,9,24,25) when viewed from the incisal

Faciolingually

Proximal contact areas are ____________ to the center of posterior teeth when viewed from the occlusal

Buccal

When viewed from the incisal, proximal contact areas are near...

The middle of the tooth Faciolingually

Overall, a distal contact area will be slightly more _________ than the mesial contact area of a given tooth

Lingual

When looking at the teeth facially, what embrasure spaces are you seeing?

Gingival embrasure and incisal/occlusal embrasure

When looking at the teeth incisally, what embrasure spaces are you seeing?

Lingual embrasure and facial/buccal embrasure

Is lingual or facial embrasure larger?

Lingual

What embrasure is often quite small?

Incisal or occlusal embrasure

Is occlusal/incisal embrasure smaller or larger than gingival embrasure?

Smaller

Interproximal space

Space between adjacent teeth

When dividing teeth into thirds horizontally (looking at the tooth facially) what are the thirds?

Cervical third, middle third, incisal/occlusal third

When dividing teeth into thirds vertically (looking at the tooth mesially or distally) what are the thirds?

Lingual third, middle third, facial/buccal third

Height of contour

Where the biggest bump is on the tooth

Height of contour is also called

crest of curvature

Where is the biggest bulk/size present on posterior teeth?

Buccal area

Ideal heights of contour lead to

Gingival health

What does food stimulate when the person chews?

The gingiva, promoting health

On adjacent teeth, the amount of curvature of the CEJ is typically...

The same

The depth of curvature of CEJ is greatest on the...

Central incisors and decreases posteriorly

Curvature of the CEJ is toward the ____________ on facial and lingual

Apex

Curvature of the CEJ is toward the _______________ on mesial and distal

Incisal and occlusal

The amount of curvature of the cervical line is normally greater on what surface?

Mesial

Periodontium

Consists of the bone and soft tissues that surround and support the teeth

Mineralized tissues of periodontium

alveolar bone

alveolus

lamina dura

Alveolar bone

portion of the maxilla and mandible that surrounds the tooth roots

Alveolus

The tooth socket within the bone

Periodontal ligament

ligament surrounding the teeth that supports and attaches them to alveoli bony surface

How many alveoli are present if 32 teeth are present?

32

Lamina dura

Thin layer of compact bone that lines each alveolus

Soft tissues of peridontium

gums

periodontal ligament

Gingiva

Gums

Gingiva is soft tissue that covers...

Alveolar bone

Attached gingiva

Tissue attached to bone

Free gingiva

Tissue not attached to bone

Parts of free gingiva

marginal gingiva and interdental papilla

Interdental papilla

Sharp, pointed projection of gingiva between the teeth

Marginal gingiva

Gingiva at the gingival margin of each tooth

Is the free gingival groove always visible?

no

Gingival sulcus

Space between free gingiva and tooth surface

Periodontal ligament contains...

Nerve endings

Periodontal Ligament fibers attach to the ____________ and ______________

cementum and lamina dura

How short are PDL fibers?

~0.2 mm

Function of the PDL

attachment and support, allows for some movement. like a trampoline

The zone between the _________ and _________________ is free gingiva covering the sulcus

gingival groove and gingival margin

Alveolar mucosa

thin, loosely attached mucosa covering the alveolar bone

Alveolar crest fibers

located at the cementoenamel junction assists with the retention of the tooth in its socket and protects the deeper fibers

Oblique fibers

from the root above the apical fibers obliquely toward the occlusal to resist vertical and unexpected strong forces

Transseptal fibers

from the cervical area of one tooth across to an adjacent tooth (on the mesial or distal only) to provide resistance to separation of teeth

Horizontal fibers

from the cementum in the middle of each root to adjacent alveolar bone to resist tipping of the tooth

Interradicular fibers

from cementum between the roots of multirooted teeth to the adjacent bone to resist vertical and lateral forces

Apical fibers

from the root apex to adjacent surrounding bone to resist vertical forces

Proper contours of facial and lingual heights of contour direct food...

away from the gingiva

Undercontoured and overcontoured heights of contour lead to

gingival inflammation

Flat contours of facial and lingual lead to

abrasion of the gingiva by food impaction into the gingiva

Bulky contours of facial and lingual lead to

lack of stimulation by food

Overcontoured=

too bulky

Undercontoured=

too flat

The free gingival groove and the mucogingival junction are the boundaries of the

attached gingiva