Tooth Eruption and TMJ Flashcards
Deciduous tooth eruption proceeds ______ to _____ in both the maxilla and mandible with mandibular teeth erupting _______
medial to lateral
slightly earlier than their complementary maxillary teeth
AKA. Mandibular CI’s erupt around 6-10 months while maxillary CI’s erupt around 8-12 months
Permanent tooth eruptions proceeds in the __________ after __________ teeth have been shed.
medial to lateral,
Deciduous
Is early tooth interruption common?
NO
But it can be followed by early eruption of permanent teeth
Is late tooth interruption common?
What is it caused by?
Yes
Nutritional deficiencies
Genetics
Metabolic Deficiencies
What is tooth impaction?
Teeth will be structurally apt but do not erupt at the occlusal surface and cause misalignment.
Very common for wisdom teeth
During which stage of tooth development does alveolar bone development occur?
Apposition stage
Permanent dentition develops from the __________ except for which teeth?
Succedaneous bud
All ADULT molars
The succedaneous bud is found _______.
Lingually
The jaw continues to grow in size until age of ______.
20
Maxillary molars are faced _______ until there is enough room for them to move.
Mandibular molars are faced _______ until there is enough room for them to move.
Max- distally
Man- Mesially
What are the 3 stages of tooth eruption?
- Pre-eruptive where there are changes in location of the tooth.
- Eruptive stage which is reflective of the movement of the tooth as it changes position in the jaw to reach the occlusal plane.
- Posteruptive stage where changes in positioning occur of the tooth as the jaw grown and teeth are being used
What are the two ways teeth move in the pre-eruptive stage of tooth eruption ?
- Bodily Movement
Shift in location of ENTIRE tooth germ within developing jaw
- Eccentric Growth
Relative growth of one part of a tooth in relation to the rest of the tooth causing a different center of gravity for the tooth
Describe differences in bodily movement between canines and incisors compared to molars and premolar.
Canines and incisors will have the permanent dentition located laterally and lingually to the primary tooth. They scootch into the spot once the primary tooth false out.
Molars and premolar tooth germs will find their way UNDER the primary tooth. Once the primary tooth falls out, it will follow the path of eruption and just replace the spot.
What exactly happens in eccentric movement during the pre-eruptive phase?
Root elongates and center of gravity changes.
Deciduous dentition has premolars. True or false
FALSE
Permanent premolars erupt ________ what tooth of primary dentition?
under
Primary molars. Root will be resorbed of the primary molar.
What lays the path for interruption of permanent teeth including molars ?
The Gubernacular Cord and Canal
When the dental lamina undergoes a ptosis, it’s remnants, or organized in the form of epithelial eyelids and strands, that lineup, leaving the reduced epithelium of the enamel organ towards the oral mucosa.
The cord itself is composed by a fibrous conjunctive tissue containing peripheral nerves, blood and lymphatic vessels.
The Gubernacular Cord establishes a ____________ where _______ cannot populate.
space in jaw where alveolar bone cannot populate
What are Gubernacular canals?
Gubernacular canals are structures formed due to the gubernacular cord stopping bone from populating in certain areas of the jaw.
These canals are the site of permanent tooth eruption and the primary dentition is shed!
Gubernacular canals are only for what kind of teeth?
Teeth that develop from the succedaneous bud.
So ALL permanent dentition EXCEPT molars which bud like a regular primary tooth.
Describe how gubernacular canals direct tooth development
The gubernacular chord travels through the gubernacular, canals, and teeth follow.
Osteoclast activity driven by components of the cord allow the canal to widen so that the tooth can erupt
What is the Gubernacular cord connect?
Dental follicle of succedaneous tooth ( the periodontum producing cells) to the oral mucosa.
What three factors drive tooth eruption?
- Root Formation
- Bone Remodeling
- Forces generated by periodontal ligament
Teeth must have roots to erupt. True or false?
False
Remember that roots form late and continue forming after tooth eruption.
Teeth pinned in place can have root growth and the bone will resorb to make space
THINK Bone is to the SURFACE of the root
(The root does not meet the bone)
PDL is has a likely role in tooth eruption. True or false?
FALSE
PDL formation happens AFTER root formation starts and begins coronally.
If root formation doesn’t affect tooth eruption, it is likely that the PDL won’t either.
What is osteopetrosis?
A rare inherited disorder were bones, hardened, becoming denser, and have low remodeling.
People with osteopetrosis have normal PD development, but teeth do not erupt.
LOW osteoclasts so bone resorption is reduced thus reducing bone remodeling
Teeth without roots, especially those ______ a detectable PDL will or will not erupt?
In teeth without roots, especially those without a detectable a PDL , teeth do erupt.
What are two pieces of evidence that tell us that the PDL is not directing tooth development?
- Osteopetrosis. Even with a PDL, teeth do not develop
- Rootless teeth have no PDL but they still erupt
Removing dental follicle cells affects tooth development how?
The teeth will develop but NOT erupt
If the tooth germ is replaced with silicone or metal and the dental follicle is present, will the fake tooth germ erupt?
Yes!!
Dental follicle is needed for eruption. True or False?
TRUE
What ultimately determines the bodily movement of teeth and eruption of teeth?
Bone remodeling of jaw via dental follicle activity
What is CSF-1 ?
Colony Stimulating Factor 1 that is a growth factor which activates osteoclastic activity
If CSF-1 is given to osteopetrotic mice, it can leads to _____________.
Osteoclast activation and tooth eruption
Osteoclasts develop from ___________ and differentiate __________.
extravasated monocytes
in situ next to developing tooth
What are extravasated monocytes?
Monocytes that have left the capillaries of vasculature and have entered the dental follicle.
When does vascularization of the tooth start?
When does it become prominent?
Late apposition stage of development
It becomes very prominent with the formation of the popularity layer, overlying the developing crown.
It becomes prominent as roots and periodontal ligaments develop.
Vascularization allows for extravasatation of monocytes in the neighborhood of the developing tooth
Describe monocyte to osteoclast differentiation.
Dental follicle cells generate MONOCYTE CHEMOTROPIC PROTEIN 1.
This recruit monocytes to extravasate and enter the dental follicle/sac.
Follicular cells will now express CSF-1 to promote differentiation of monocytes into osteoclasts.
What two factors are key for differentiation of monocytes to osteoclasts?
MCP-1 for recruitment of monocytes into dental follicle from vessels
CSF-1 for differentiation of monocytes into osteoclasts
Describe tooth exfoliation of canine and incisors.
Describe the status of
Root
Pulp
Bone
PDL
Permanent teeth develop on LINGUAL side
Little loss of root, pulp and bone when exfoliation occurs.
PDL is lost rapidly as cells undergo apoptosis
Prior to exfoliation of the PDL of deciduous molars what happens?
Roots are primary molars are resorbed
What is the difference in exfoliation of deciduous incisors and canines compared to molars?
Deciduous molar roots get resorbed.
Deciduous incisors and canines keep their roots
What happens during the post eruptive stage?
- Periodontal ligaments attain mature patterns of fiber groups
- Gingivalfiber groups develop
- Final growth pattern of vascularization and innervation of PDL
What is mesial drift?
It is the anterior or medial adjustment of teeth with the jaws as a hole due to alveolar bone remodeling from mastication and angle of jaws
Bone resportion occurs anteriorly in each socket and addition posteriorly
The maxilla moves. The mandible is static.
True or False
FALSE
Maxilla is static
Mandible moves via TMJ
The TMJ articulates with ________
The underside of the squamous portion of the temporal bone of the skull called the Glenoid Fossa
and
the condyloid process in the mandible.
What is the condyloid process?
A site located posteriorly on the mandible.
Kind of like the highest part of mandible furthest to the back
The condyle and fossa form a ___________ joing.
Ginglymoarthrodial Joint (TMJ)
Ginglymus : Hinging
Arthrodial : Sliding
The TMJ is enclosed by a _______. What is it made of?
Connective tissue capsule
Dense fibrous membrane that surrounds TMJ and incorporate articular eminence, articular disc and neck of mandibular condoyle at 4 different sheets
What are the 4 sheets created by the capsule covering the TMJ?
- Anterior: to Ascending slope of articular eminence (Glenoid Fossa)
- Posterior: to lips of squamous tympanic fissure (Glenoid Fossa)
- Superiorly to Glenoid Fossa
- Inferiorly to neck of condyle
What two structures of the temporal lobe are key for attachment of the TMJ?
- Articular tubercule of temporal bone (anterior to fossa)
- Tympanic Part (posterior to fossa)
What covers the glenoid fossa?
What covers the mandibular condoyle?
What separates condoyl and fossa surfaces?
Inner and outer fibrous connective tissue articular layer
Fibrous articular Layer
Synovial cavities and articular disk
The articular disk will be the large central portion on histology while the synovial cavity will be lining the disk as a lighter color.
What is the articular disc?
Does it have vasculature or nerves?
Fibrous extension of capsule in between bones of joints that is DENSE REGULAR CONNECTIVE TISSUE that is surrounded by a synovial cavity.
Does NOT have vasculature or nerves.
Synovial membrane lines the _____ and makes the _________ of the joint.
It consists of _____ and ______.
What is synovial fluid high in?
capsule, synovial fluid
Cellular intima (Macrophage and Fibroblast type cells)
Vascular subintima
Synovial fluid is rich in hyaluronic acid, a GAG, that makes it viscous
What are sensory receptors of the joint and their associated structures ?
- Ruffini’s Endings
Found in joint capsule that can detect changes in position or general changes in the joint
- Pacinian Corpuscules
Found in Joint capsule, pressure receptor detecting joint movement.
What makes synovial fluid viscous?
Hyaluronic Acid secreted by intima
Sensory receptors of the joint are found in the _________ and are called _______-.
Joint capsule
Ruffinis Endings
Pacinian Corpuscules
