Part of the tooth that includes the PDL cementum and alveolar bone
connective tissue that connects the tooth root to the bone via the cementum
True/False: all of the fibers are not perpendicular to the tooth; different fibers take different stresses.
what is the PDL made of?
the tensile strength of the PDL is great than
what is the average width of the PDL?
0.2 mm (related to function)
0.2 mm is a static measurement – if you increase that measurement, there will be an adaptation of the bone to bring that measurement back to 0.2 mm. Also explains why a widened PDL has a force on the tooth.
Functions of the PDL (3)
allows movement of the tooth in socket
acts as a "shock absorber" during infection
provides sensory information during function
What happens to the PDL with loss of alveolar bone?
it disappears and this increases mobility of the tooth
little fibers at the end of the PDL that inject into the cementum and the alveolar bone to help keep the PDL connected
What are the 6 principle fibers of the PDL?
interradicular (only for multi rooted teeth--located in the furcation)
transeptal fibers run inter proximally ____ the bony crest
When healthy the alveolar bone is ___ mm apical to the CEJ
how to alveolar crest group fibers run?
downward from the heigh of cementum to alveolar crest
Horizontal fibers form ____ ___ to the long axis of the tooth
fibers that run upward form cementum to alveolar bone-->tension fibers
which fibers prevent the teeth from being drive in the apical direction and constitute the majority of the PDL
5 physical functions of the PDL
attach teeth to bone
secure gingival tissues in proper relationship to teeth
shock absorption during occlusal load
transmission of occlusal forces of the bone
provides "casing" of protection for nerves and vessels of the dental unit
3 formative and remodeling functions of the cells of the PDL
formation and resorption of bone, cementum and the PDL itself
accommodation to occlusal forces
repair of injuries
True/False: If the PDL tears with too large of a force, chances that the PDL may not reform and ankylosis will occur. Root resportion may result and tooth may need to be extracted.
True/False: When the tooth is moved toward the one side the opposite side side will expand out to enlarge the PDL space and the other side will get smaller to keep the 0.2 mm width
What is the nutritional function of the PDL
provides nutrients to cementum, bone and gingiva via blood vessels
what is the sensory function of the PDL
provides tactile, pressure, and pain sensation vita trigeminal nerve
elimination function of the PDL
provides lympathic draining
calcified avascular tissue that forms the outer covering of the anatomic root
Fill in the following regarding cementum
primary purpose: anchor teeth via PDL
type: cellular and acellular
True/False: cementum deposition is continuous
Cementum repair is dependent on viable _____
True/False: repair can occur in devitalized teeth
Type of cementum that is first to be formed, in the cervical 1/2 to 1/3 of the root surface and shows significant calicfication
type of cementum that is formed after full eruption to occlusal plane, less calcification and thicker layer than acellular cementum
the type of CEJ that occurs 5-10% of the time
space between the cementum and enamel
the type of CEJ that occurs 30% of the time
end to end relationship between enamel and cementum (they meet but don't overlap)
the type of CEJ morphology that occurs 60-66% of the time
cementum overlapping enamel
C over E!
usually found in the apical 1/3 of the root, super eruption of the teeth, low-grade periapical irritation and associated with Paget's disease is characteristic of what?
usually related to excessive force of ortho and or occlusion
what are the 6 local etiologies for cementum resorption
erupting or misaligned teeth
replanted and or transplanted teeth
periapical and or periodontal disease
what are the four systemic etiologies for cementum resorption
hereditary fibrous osteodystrophy
1. cementum repair requires presence of viable connective tissue
2. epithelium will NOT block repair process
3. Cementum repair possible in vital and devitalized teeth
2. false--it WILL block repair process
The following are characteristics of:
Dysregulated bone remodeling
Excessive bone breakdown and subsequent disorganized new bone formation
Multiple bones - pelvis, femur, and lumbar vertebrae, and skull
> 55 yrs old
fusion of the cementum and alveolar bone without the presence of a PDL
Sounding of an ankylosed tooth by percussion differs from that of a tooth with a PDL. Similar to percussion of implant--- why?
without the PDL acting a shock absorber, the sound is being transmitted through the bone.
Ankylosis is seen in teeth with (3)
chronic peri-apical inflammation
portion of the maxilla and the mandible that forms and supports the tooth sockets (alveoli)
True/False: the alveolar process remains intact after tooth loss
gradual resorption after tooth loss
When does the alveolar process form?
it forms with the erupting tooth and PDL
____ _____ forms the skeletal structure at the apical portion of the alveolus.
What two things can happen if the root proximity is too small (narrow)
little blood supply
faster bone loss
True/False: Osseous crest should not be at the CEJ in healthy people because need cementum coronal to the osseous crest to allow for a soft tissue attachment.
The osseous crest parallels ___
CEJ-CEJ between teeth
the denuded areas extending through the marginal bone
looks like the tooth is completely coming out (the entire length of the root is coming out)
isolated areas in which the root is denuded in bone
Looks like just a portion of the root or apex is showing