L3- last of 'the tour' Flashcards
(107 cards)
1
Q
three types of junctions b/w a tooth and periodontal tissues
+ brief description
A
- gomphosis joint - via PDL, cementum and alveolar bone (bundle bone, cribriform plate, inner cortical plate
- Dentinocementum Junction (DCJ) - involves the hyaline layer of hopewell smith and cements the cementum to the mantle dentin
- CEJ - cementoenamel junction
- butt joint b/w cementum and enamel
- overlap of cementum onto enamel
- gap between cementum and enamel
2
Q
what is cementum - general
principle function?
A
calcified covering over the dentin of the roots (50-200 um)
principle function = provide anchorage of tooth to alveolus through the collagen bundles of periodontal ligament SHARPEYS FIBERS
HARD AVASCULAR C.T.
- chemical structure more like bone
- mineralized outer layer - collagen fibers of periodontal ligament are inserted
3
Q
T/F cementum becomes pathologically altered during Perio disease
A
TRUE – it can be lost following disease process and is associated with periodontal tx.
spontaneous and therapeutic regeneration of cementum has been difficult to achieve
4
Q
major difference between bone and cementum
A
Cementum is AVASCULAR – so it NO OSTEON -LIKE STRUCTURES
- gets nutrition / vascular diffusion from PDL - not osteons
- relatively thin and limited repair /regeneration
5
Q
is cementum a reservoir of minerals?
A
NO – therfore more static than bone
6
Q
function of cementum
A
- attachment/ support via acellular cementum plus the hyaline layer
- adapation/ protection - during tooth movement and weating - via cellular cementum
- assist in mainting occlusal relationships - maintain width of PDL at apex
7
Q
relationship between attirtion and cementum
A
attrition is the wear of the occlusal surfaces and with this there is continual erupting as a result which is termed ACTIVE ERUPTION – which is proportional to the amount of attrition – this process is accomplished via cementum deposits of cellular cementum at the apical ends of roots - which push tooth up
8
Q
supraeruption
A
if no opposing force of tooth – continues to erupt via the deposition of cellular cementum at the apex of teeth with no antagonist tooth
9
Q
which is less susceptible to resorption; alveolar bone or cementum?
A
cementum - so provides protection too
10
Q
is cementum poorly mineralized?
composition?
A
yes - poorly mineralized.
60% inorganic (opposed to dentin which is 70% inorganic and enamel which is 95% inorganic)
11
Q
bone composition
mineral
organic
water
A
mineral/ inorganic = 45%
organic = 30%
water = 25%
12
Q
cementum vs bone
A
cementum contains ONLY TYPE I COLLAGEN
- more permeable
- no extensive remodeling like bone so DOES NOT TURN OVER – NOT RESORBED PHYSIOLOGICALLY
- 60% inorganic
- 27 % organic
ALVEOLAR bone
- 45 % inorganic
- 30% organic
- type I and type II collagen
13
Q
resorption in cementum?
A
NOT PHYSIOLOGICALLY BUT IN PATHOLOGICAL CONDITIONS
- resorption due to inflammation
- resorption due to orthodontic tooth movement
14
Q
cellular vs. acellular cementum
where?
turnover?
A
Cellular –> more towards apex and cementocytes get trapped in lacunae / in matrix as it calcifies (origin of cementocytes)
acellular –> covers coronal aspect of the root and has NO CEMENTOCYTES and after tooth errupts there is no longer any formation of this
15
Q
two types of collagen in cementum
A
- intrinsic fibers – during initial formation and as the cementoblasts lay it down and calcification occurs – become trapped
- sharpeys fibers that get imbedded within the cementum from the PDL
- formed by fibroblasts
16
Q
major cell types associated with cementum
A
- cementoblasts
- cementocytes
- PDL ligament fibroblasts
- odontoclasts/ cementoclasts
17
Q
cementoblasts - origin and describe
A
from ectomesenchymal layer within the dental follicle – later on may come from undifferentiated cells in the PDL
- morphologically similar to fibroblasts - but located in close proximity to the cemental surface and extend cytoplasmic processes towards cementum
18
Q
what do cementoblasts produce? how is this arranged
A
produce the intrinsic collagen fibers and their long axis is more/less parallel to tooth surface
(opposed to the extrinsic collagen fibers from PDL that are more/less perpendicular to tooth surface)
19
Q
what secretes cementum matrix?
rate?
location?
A
cementoblasts do by apposition at the cemental surface
- grows slowly in thickess throughout life - but NOT REMODELED continuously (like bone)
20
Q
cementocytes
how produced?
A
over rapid periods of cementogenesis - cementoblasts that become TRAPPED W/IN LUCUNAE – then have cytoplasmic processes extending toward cemental surface through canaliculi
- less organelles = less metabolic/ very little metabolic activity
21
Q
periodontal fibroblasts considered cementum cells?
A
YES – b/c although not produced by them they become mineralized as they become incorporated into cementum - so they do contribute to cementogenesis
22
Q
odontoclasts aka?
function?
type of cell?
A
aka –> cementoclasts
multi-nucleated giant cells
involved in the resorption process but are indistinguishable from osteoclasts
23
Q
three relationships between cementum and enamel at the CEJ?
percentage of each?
can they co-exist?
A
30% = Butt joint – > do not overlap but meet up against each other
60-65% = OVERLAP (cementum overlaps enamel)
5-10% = GAP b/w the enamel and cementum - which can expose dentin on root - may have root sensativity problem
*these realtionships can co-exist on a single tooth
24
Q
cementicles
describe + types?
implications
A
developmental anormality in which a clump of afibrillar or fibrillar cementum (or mixture) gets either attached/sessile to the cemental surface or lie free within the pdl adjacent to cementum – can mimick calculus and the attached ones may serve as a promoter of periodontal disease if exposed
imbedded ones have no clinical relevance
25
is cementum usually exposed?
| clinical correlations
NO -- usually covered by alveolar bone and gingiva
EXPOSED W/ GINGIVAL RECESSION OR PERIO POCKETS
PERMEABLE TO PLAQUE BACTERIA -- so can get to the dentin subjacent to pathologically exposed cementum
26
can CT cells adhere to previously exposed cementum?
| implication?
NO -- cannot adhere to previously exposed OR toxin-containing cementum
27
clinical correlations to scaling and root planning relating to cementum
this process is aimed at removing claculus and bacterial deposits often removes the relatively thin layer of cementum --- which leaves underlying surface with a 'smear-layer' and unknown findings whether or not this layer allows for new cementum formation -- may be a clinically weaker junction now
28
new cementum formation? goal?
because cementum mediated attachment of the tooth to the PDL and bone this is a high sought out therapeutic measure - however limited repair and regeneration capacity
29
can alveolar bone fuse directly with cementum or dentin?
| what is this called?
YES -- ankylosis but this is undeserible b/c get increased resoprtion from osteoclast activity
30
function of the hyaline layer of cementum?
'cements' the cementum to the MANTLE dentin
31
acellular cementum primary function
attachment function
32
cellular secondary cementum function
ADAPTION
33
what makes PDL ligament 'not' a ligament in terms of its functions and characteristics
- rich vascular supply with array of cellular components for allowing homeostasis and repair
- hydrodynamic interactions is a key function
- vascular and lymphatic vessels to PDL supply nutrients and remove metabolic by-products
may be called PERIODONTAL MEMBRANE b/c ligament is a misnomer as a ligament is (usually) dense, avascular, band of connective tissue with limited ability to repair /heal
34
T/F the PDL contains the progenitor cells of the dental follicle necessary for regeneration of cementum and bone as well as PDL?
TRUE
35
five main key functions of the PDL?
1. supportive
2. nutritive
3. sensory
4. formative
5. healing
36
extracellular fibers of PDL composition?
| function?
composed mainly of collagens and associated molecules that CONNECT cementum with alveolar bone
37
cells in PDL that are responsible for maintenance and regeneration?
fibroblasts, neurovascualr elements of periodontal tissues like progenitor undifferentiated cells
38
how does PDL carry out adaption? via?
viscoelastic components
| - designed primarily to withstand he considerable forces of mastication and/or bruxism & nocturnal grinding of teeth
39
how does PDL carry out attachement? via?
via tensile strengh components desginged to connect teeth to bone
40
how does PDL carry out sensory perception? via?
nerves -- designed both to properly position the jaws during normal function and to withstanf the occlusal forces
41
how does PDL absorb light/moderate/ heavy forces?
light -- ibtravascular fluid pushes out of blood vessels
moderate -- extravascular fluids forced out of pdl space into adjacent marrow spaced
heavier-- taken up by principle fibers
42
healing of bone grafts?
via the PDL
43
major blood supply for pdl
originating from dental arteries that enter ethe fundus of the alveoli
and major anastomoses exist b/w blood vessels in the adjacent marrow spaces and gingiva
44
are nerves of pdl myelinated?
the ones that perforate the fundus of the alveoli are but then they lose their myelination as they enter and branch to supply the pulp and pdl
45
nerve endings of pdl
primarily receptors for pain and pressure
46
describe the foramtive funciton of the pdl
provides cells that are able to form as well as absorb all the tissues that make up the attachment apparatus - bone (osteoblasts), pdl (fibroblasts), cementum (cementoblasts)
the undifferentiated ectomesenchymal cells are located around the blood vessels -- can then differentitate into these cell types
47
bone and tooth -resorptive cells in pdl derived from?
ostecloasts and odontoclasts -- generally multinucleated cells derived from blood-borne macrophages
48
principle fiber groups of pdl and compromised of?
| all extend where
mainly type I collagen bundles
all extend from cementum to bne
1. alveolar crest fibers
2. horizontal fibers
3. oblique fibers
4. apical fibers
5. interradicular fibers
49
60% of all pdl principle fibers are what type?
oblique fibers
50
alveolar crest fibers where
| function?
run from the root to the osseous crest of bone
function -- retain root in socket; oppose lateral forces - protect deeper periodontal ligament structures
51
horizontal fibers run where
| function
horizontaly from bone to root
function - resist lateral forces
52
oblique fibers run where
| function?
radiate from the apex of the tooth root to bone
function -- resist axially directed forces
53
apical fibers where
| function?
```
radiate from the apec of the tooth root to bone
function - prevent tooth tipping and resisit luxation and protect blood, lymph and nerve supply to the tooth
```
54
interradicualr fibers where
| function?
run from cementum in the bi-tri-furcations and spread APICALLY towards the furcal bone
function - aid in resisting tipping and torquing; resist luxation
55
mineralized vs. non mineralized portions of sharpeys fibers?
| implication on names of these fibers
non-mineralized = what we actually call sharpeys fibers vs mineralized is the part in the ligament proper
56
diameter of type I and type III collagen mixture in PDL?
| relatively big or small?
about 55nm
| - considered relatively small
57
where are sharpeys fibers fully mineralized vs partially
fully --> acellular cementum
partially --> cellular cementum and bone
58
what type of elastic fibers are found within the PDL?
IMMATURE ELASTIC FIBERS
| - Oxytalin & Elaunin molecules
59
Oxytalin & Elaunin molecules
IMMATURE ELASTIN FIBERS
- found within the PDL w/ extensive distribution
- running in an apico-coronal direction within the PDL
- forming a 3-D branching network that surrounds the root
- most likely functioning to regulate vascular flow in response to tooth function --- viscoelastic shock absorber characteristics
60
main components of ground substance in PDL
Dermatan Sulfate is the main PG/GAG
PG and GAGS are most important in withstanding stress loads during normal function because of their high density of - charges and large water component (70% of mass in ground substance)
61
odontoclasts?
| resemble?
resembling osteoclasts
62
resorbing cells include?
odontoclasts and mononuclear cells
63
mononuclear cells resemble?
macrophages
64
what serves as the main source of new cells? called what?
PDL is the primary source of the pluripotential cells (undifferentiated ectomesenchymal cells) that can be precursors to cementum, alveolar bone and fibroblasts
65
rests of mallasez?
where would they be?
can develop into?
in the PDL -- remnants of hertwig's epithelial root sheath
if present they are in the APICAL portion and have no known function
if proliferate they form LATERAL PERIODONTAL ROOT CYSTS
66
MAJOR VASCUALR SUPPLY TO PDL
THROUGH THE APICAL FORAMEN FROM THE BLOOD SUPPLY ORIGINATING FROM DENTAL ARTERIES
67
neural elements within PDL
| myelinated vs unmyelinated?
responsible for the pressure and pain sensations as these are the associated free nerve endings
myelinated near the apical end and unmyelinated more coronally
closely following the distribution of the arterial supply
**these are what quantitate and locate the object when one bites down hard on something
68
mechanism of traction provided by the PDL?
compression and tension
- this is of the osseous socket wall during tooth eruption and orthodontic movement
69
what joint in pdl limits tooth movement during normal occlusal function?
gomphosis
70
what acts as a resoivor for the pluripotent cells recruited during periodontal wound healing?
PDL
repair and regeneration as it is a dynamic, biomechanical tissue
71
hypo and hyper function of the PDL
average width of pdl?
width is normally about .2mm -- but alters based on the function of the loasds placed on the tooth
increases in width in hyperfunction
pdl decreases when not used for an extended period of time
72
major function of alveolar bone in the periodontium
1. protection
2. support
3. reservoir of minerals -- which reflects the dynamic status of bone
73
3 parts of the elveolar process
1. cribriform plate
2. supporting plate
3. outer plate
74
cribriform plate
| where? function? composition?
Closest to the pdl area and is of CORTICAL BONE which has the sharpeys fibers of the pdl inserted into it
75
supporting plate
| where? function? composition?
between the cribriform plate and the outer plate
is of CANCELLOUS BONE --> has trabecular and marrow
- in children has marrow that is hematopetic
- in adults marrow is more fatty and converts to a fibrous state in periodontal inflammation
76
outer plate
where? function? composition?
what is special about this one?
THERE ARE TWO
- facial and lingual
- also composed of cortical bone and is covered with periosteum
*contious with the body of the maxilla and mandible
77
periosteum location?
layers?
function of layers?
covers outer plates and is composed of two layers
- outer fibroud layer
- inner cambium layer --> CONTAINS OSTEOBLASTS AND OSTEOCLASTS and their precuroses -- so it is the active layer
78
three functions of the periostoeum
1. attaches gingiva and alveolar mucosa to bone
2. provides innervation, lymphatic drainage, and blood supply to bone
3. participated in the healing of periodontal wounds
79
distinguish between alveolar process and alveolar bone
process --> portion of the jawbone that contains teeth and the alveoli in which they are suspended -- RESTS ON BASAL BONE
bone --> lines the alveolus (or tooth housing) composed of a thin plate of cortical bone with numerous perforations (cribriform plate) that allows the passage of blood vessels b/w marrow and the pdl
80
proper development of alveolar process depends on?
tooth eruption and its maintenance on tooth retention
81
if adontia what fails to form?
when teeth fail to form --> the alveolar process fails to form
82
what happens to the alveolar process in edentoulism?
most of the process becomes INVOLUTED --> so leaves basal bone as the major constituent of the jawbone -- therefor it is REDUCED in height
83
alveolar/ osseous crest
where the cribriform and outer plates MEET --> OSSEOUS CREST
- the most coronal portion of the alveolar process
84
interdental septum
portion of alveolar process that is located between the teeth
composed of the cribriform, outer, and supporting plates
85
position of osseous crest of bone
1 mm apical to the CEJ
*location is not altered by changes in the tooth position but can be changed via inflammation and trauma
86
bone morphology in relation to thickness
thickness of the cortical plates varies significantly from tooth to tooth
- labial and buccal plate generally thicer than lingual except in the incisor region
- palatal cortical plate is usually thicker than the facial plate of the maxilla
87
what is a major determinate for cortical plate thickness and contour
position of teeth in the arch
88
mesial distal sections - shape of the alveolar crest is determined by?
contour and width of the interdental space, degree of tooth eruption, and the position of adjacent teeth
89
CEJ relationship to alveolar crest
if CEJ's are even - alveolar crest is more horizontal .. if they are on an uneven plane or inclined - then alveolar crest take on more of an oblique orientation
90
what appears light and dark on a radiograph?
| what about the lamina dura?
non-mineralized tissues = dark
dense structures like teeth and bone appear LIGHT - like teeth and bone
LAMINA DURA -- WHITE LINE that parallels the outline of the roots in a radiograph
91
radiographic term for line that parallels the outline of roots of the teeth
lamina dura
92
what does the pdl space look like on radiograph?
appears as dark line between the lamina dura and the root surface
93
trabecular pattern in which type of bone in alveolar process?
cancellous
94
bone produced by? origination of these cells?
osteoblasts -- from a less differentiated precursor within the periosteum, endosteum and periodontal ligament
- ectomesenchymal differentiation
95
what is the system within the compact bone?
cylindrical units -- osteons or haversian systems
- each osteon has a central haversian canal and linked to others via volkmans canal (which are perpendicular to them)
96
most of tooth support in center of jaw is provided by what type of bone?
cancellous bone
97
what does remodeling of alveolar process allow for?
normal migration of teeth in a MESIAL DIRECTION -- or mesial drift (as interproximal sufaces ware down)
- also allows for orthodontic tooth movement and wound healing
98
a reversal line aka?
| what does it identify?
REV
- dark staining scalloped line and outlines the resoprtion front created during the previous phase of bone resorption and the following it will be new bone deposited by osteoblasts within the PDL
99
fenestration in bone?
clinical variation which there is a hole in bone by totally circumscribed by bone
100
dehiscence in bone?
hole in bone with no coronal margin
101
where can holes be anticipated clinically?
in teeth which ahve prominant roots in the arch like maxillary cuspids and MB root of max first molar
difficult to see on radiographs
102
clinical importance of fenestrations and dehiscences
could worsen if go to do a gingival flap therapy
- surgical interventions could promote the conversion of fenestration to a dehiscences
also fenestrations can lead to dehiscences which in turn can lead to gingival recession
103
if root proximity is close what does this mean?
interdental space is narrow and the septjum may consist mostly of cortical bone -->
absence of any support between the teeth if a "window" b/w the teeth is found (connected at bottom then whole then reconnected)
104
resorption leads to?
mobility of teeth and the associated loss of function (Periodontal disease)
105
T/F bone is mineralized
TRUE -- mineralized CT with a lot of type I collagen and other associated structures
106
what mechanism forms alveolar bone?
intramembranous
107
clinically, alveolar bone is manipulate during various types of what periodontal therapy
1. resective surgery
2. regenerative surgery
3. implant surgery
