Ten cates oral histology ed 8th and some Flashcards
(170 cards)
1
Q
3 most common types of apatite crystal in enamel:
A
carbonated hydroxyapatite (CAP) hydroxyapatite (HAP)
fluorohydroxyapatite (FHAP)
2
Q
what is the radiological density of dentin, enamel and cementum
A
The radiological density of cementum is approximately 1200 - 1500 Hounsfield “units” (H).
density of dentin is 1600 - 1800 H.
Enamel is 96 – 98 % inorganic material, with a density of 2400 - 2600 H
3
Q
How many dentin tubules are there per root
A
There are 30,000-75,000 dentin tubules/mm2 root
4
Q
Lingual tumors are an uncommon occurrence in the dog, accounting for only ?% of oral tumors.
A
Lingual tumors are an uncommon occurrence in the dog, accounting for only 2-4% of oral tumors.
5
Q
of lingual tumors, malignant tumors comprised ?% of reported neoplasms with ? and ? being the most frequent.
A
of lingual tumors, malignant tumors comprised 64% of reported neoplasms with malignant melanoma and squamous cell carcinoma being the most frequent.
6
Q
Dental fractures in domestic dogs are common. The prevalence is reported to be as high as ?%.
A
Dental fractures in domestic dogs are common. The prevalence is reported to be as high as 27%.
7
Q
When does bone lysis between radiographically evident
A
Bone lysis becomes radiographically evident when
more than 40 % of the compact bone has been already demineralized;
8
Q
Acellular cementum is derived from what component of the tooth germ
A
Dental follicle also called dental sac
9
Q
What is passive eruption
A
Passive eruption refers to the uncovering of the anatomic crown because of apical recession of the surrounding tissues (junctional epithelium and alveolar bone), rather than bodily movement.
10
Q
Who classified the stages of passive eruption
A
Gottlieb and Orban
11
Q
Who many stages are there of passive tooth eruption
A
4
12
Q
How many types of altered passive eruptions are there
A
Type Ia, Type Ib, Type 2a, Type 2b (Coslet)
13
Q
What tooth germ layer does the Junctional epithelium come from
A
The reduced outer enamel epithelium layer from the enamel/dental organ of the ectoderm.
14
Q
Who developed the Periodontal Index (PI)
A
Russell
15
Q
Who developed the Periodontal Disease Index (PDI)
A
Ramfjord
16
Q
Tooth eruption is the result of what two types of eruption
A
Active and passive eruption.
17
Q
Name the three zones of the caries lesion
A
1) translucent zone (demineralisation zone)
2) Dark zone (mixed de/re-mineralization zone)
3) body of the lesion zone
18
Q
Name the four types of nerve endings to the TMJ
A
1) Ruffini’s corpuscles (to the capsule, Proprioceptin)
2) Pacini’s corpuscles (to the capsule, mechanoreception)
3) Golgi tendon organ
4) Free nerve endings (most abundant, nociception)
19
Q
name the major immunoglobulin of saliva
A
ImmunoglobulinIgA
20
Q
name the two main secretory cells of the saliva glands
A
- Mucous
2. Serous
21
Q
What does serous saliva glands produce
A
- proteins
2. glycoproteins
22
Q
is saliva hypotonic, isotonic or hypertonic?j
A
Hypotonic
23
Q
Name the principal cells of the PDL
A
Fibroblast
24
Q
Name the nerve supply to the salivary glands
A
They are innervated by postganglionic nerve fiber of the sympathetic and parasympathetic autonomic nervous system
25
name the parasympathetic cranial nerves that innervate the salivary glands
Via the superior or inferior salivary nuclei in the brainstem via CN VII (facial) through the lingual nerve - submandibular gland
-"- CN IX (glossopharyngeal) through the auriculotemporal nerve - Parotid
26
Descrbe the path of the sympathetic nerves that innervate the salivary glands
preganglionic symphatetic nerve via Thoracic spinal cord to the postganglionic neurons in th superior cervical ganglion - with the arterial blood supply to the gland
27
Name the non-principal cells of the PDL
1) Epithelial cells (remnants of HERS) - known as epithelial cell rests of Malassez
2) Undifferentiated mesenchymal cells
3) Stem cells (differentiate into adipogenic, cementogenic, osteogenic and chrondrogenic cells)
28
Name the fiber groups of the PDL
1) Alveolar crest
2) horizontal
3) oblique (most abundant)
4) Apical
5) interradicular
29
Name the three types of elastic fibers in the periodontium
Elastin
Oxytalan (only one found within the PDL)
Elaunin (found within the fibers of the gingival ligaments .
30
Name the different tooth movements, during eruption
1) Preeruptive movement
2) Eruptive movement
3) Posteruptive
31
What is the gubernacular cord?
It is the fibrocellular follicle surrounding a successional tooth, that retains its connection with the mucosal membrane by means of a strand of fibrous tissue containing remnants of the dental lamina
32
what are the gubernaculum canals?
Are canals were the gubernaculum cords use to sit in the bone. They delineate the eruptive pathways for the permanent teeth.
33
what is released just prior to eruption of a tooth that cause the redness of the gum
Enamel matrix proteins are released just prior to and during
mucosal penetration, resulting in a local hypersensitivity
reaction and clinical signs including erythema
34
Name the theories of the eruption mechanism
1) Root elongation
2) Alveolar bone remodeling
3) PDL force formation
4) Dental follicle force (hydrostatic force)
5) Gubernaculum contraction
35
name the 3 phase of tooth eruption
pre-eruptive phase where
the dental germ moves
pre-functional phase once the crown
has formed and root formation begins. intraosseus and
a supraossesus phase.
functional phase
that begins once the tooth comes into occlusion,
36
Are there any changes in the cementum at orthodontic tooth movement?
no - theoretically, but some damage will likely happen due to the forces applied.
37
Describe the orthodontic tooth movement over time
1) Initial compression phase
2) Hyalinization phase (10-20 days) - ligaments that undergo this process (Lag phase)
3) further tooth movement (Postlag phase
38
what is the Nasmyth membrane
During enamel
production, the enamel organ is compressed and the ameloblasts
form a protective layer known as the primary enamel cuticle , or
Nasmyth’s membrane . The primary enamel cuticle (also known as
reduced enamel epithelium) acts as a protective layer for erupting
39
When does clinical demonstrable resorption of teeth occur with orthodontic movement?
Only after application of heavy forces and the movement of teeth for more than 30 days.
40
Types of Cementum
* Acellular cementum - contains no cementocyte within the mineralized tissue. Covers the cervical 1/3-1/2 of the tooth
* Cellular cementum - contains cementocytes within its mineralized tissue. Covers the apical half of the root.
41
Salivary Ductal System consists of?
- smallest ducts in contact with acini, larger as they empty into collcting duct until oral cavity
- has secretory portion within acinar cells, and excretory portion in connective tissue
- secretory portion substances enter and leave by ion exchange with blood vessels, excretory is just a saliva collecting tubule
- acinar cells drain directly into intercalated ducts that open into striated ducts (both intralobular), then into interlobluar ducts
42
What are the 5 major proteins of enamel?
1. Amelogenin
2. Ameloblastin
3. Enamelin
4. Kallikrin 4
5. Mmp-20
43
Major matrix protein of Enamel
Amelogenin (several isoforms)
44
Major matrix protein of Dentin
Collagen (type 1)
45
Noncollagenous matrix proteins of dentin are?
1. Dentin sialophosphoprotein
- Dentin glycoprotein
- Dentin phosphoprotein
- Dentin sialoprotein
2. Dentin Matrix protein 1
3. Bone sialoprotein
4. Osteopontin
5. Osteocalcin
6. Osteonectin
46
Nonamelogenins matrix proteins in enamel are?
1. Ameloblastin
2. Enamelin
3. Sulfated protein
47
Inheritance of Dentinogenesis imperfecta
results from an inherited structural deficiency in collagen formation
- Since dentin and bone is supported by a collagen framework, dentin affected by this disease is structurally defective
- Several types of the condition are recognized, most are Type II . while Type I is coupled with osteogenesis imperfecta
48
This cartilage is in the first branchial arch.
Meckel's cartilage
49
2nd branchial arch -Cartilage
Reichert's cartilage:
* Stapes
* Styloid process
* Stylohyoid ligament
* lesser horn hyloid
50
Innervation and vascularization of Pharyngeal Arches
1. First arch: Trigeminal nerve V
2. Second arch: Facial nerve VII
3. Third arch: Glossopharyngeal IX
4. Fourth arch: Vagus X
51
secondary palate formation
- Nasal septum growns downward form the frontonasal process.
* the bilateral maxillary processes give rise to two palatal shelves (lateral palatine processes). Grow inferiorly and deep on the inside of the stomodeum in a vertical direction along side of the developing tongue. The tongue is forming at the same time.
* Shelf-elevating forces the the palatal shelves to flip superior within a few hours.
* The palatal shelves elongate and move medially toward each other to form the secondary palate.
* Will give rise to the posterior two thirds of the hard palate and contain the maxillary canines and posterior teeth, the uvula, and soft palate, the median palatine raphe, and under the median palatine suture on the adult bone.
52
Describe the formation of the tongue
First pharyngeal arch develops tuberculum impar protuberance.
Two lateral lingual swellings develop, fuse at median sulcus-> Anterior 2/3 of tongue
Large midline swelling (copula) develops from the 2nd, 3rd and 4th arches give hypobranchial eminence, which develops into posterior 1/3
53
Centers of ossification in mandible. How many?
two- anteriorly separated by the symphysis - that grow backwards
54
Secondary (Growth) Cartilages in Mandible are?
- occupies most of ramus, quickly ossified
- thin remnant remains into teens, important for mandible growth
1) Condylar Cartilage: ossification center for ramus - endochondral ossification
2) Coronoid Cartilage: appears at 4 months then disappears immediately
3) Symphysial Cartilage: develops at ends of Meckel's cartilage
55
Development of maxilla is it similar to the mandible?
There are no arch cartilage or primary cartilage but the center of ossification is closely associated with the cartilage of the 1) nasal capsule and the 2) zygomatic or malar cartilage
56
Name the three structural elements of the cytoskeleton
- microtubules (25 nm in dia)
- microfilaments (6-8nm in dia.)
-intermediate filaments (10 nm in dia)
57
What is the primary epithelial band?
A continuous horseshoe-band of thickened epithelium in the location of upper and lower jaws
58
The primary epithelial band divides into
Dental lamina
| Vestibular lamina
59
dental placodes
mark the sites of tooth development
60
Three stages of tooth development are?
Bud
Cap
Bell
61
what controls the position and number of tooth germs along the oral surface?
- signals appear to originate from oral epithelium
- Fgf-8 plays role in oral-aboral axis and seems to play role in determining positions where tooth germs will form
- Pax-9 gene (one of earliest mesenchymal genes) - define localization of tooth germs
- Pax-9 is induced by Fgf-8 and is repressed by bone morphogenic proteins (BMP-2 and 4).
- Fgf-8, BMP-2 and 4, expressed in non overlapping areas (Pax=9 expressed at sites where Fgf-8 is but not Bmp)
- Shh also implicated in tooth initiation
62
Name and describe 2 hypothetical models proposed to explain how different tooth shapes developed
1. field model - proposes that factors responsible for tooth shape reside within ectomesenchyme in distinct graded and overlapping fields for each tooth family
2. clone model - proposes each tooth class is derived from a clone of ectomesenchymal cells programmed by epithelium to produce teeth of given pattern
63
Describe the first stage of tooth development
Bud stage: First epithelial incursion into the ectomesenchyme of the jaw. The epithelial bud continues to proliferate into the ectomesenchyme, cellular density increases. The process is referred to as the Condensation of the ectomesenchyme
64
* What does the transition from bud to cap mark?
* Onset of morphologic differences between tooth germs that give rise to different types of teeth.
* Msx-1 is expressed with Bmp-4 in mesenchymal cells that condense around tooth buds
* Multiple other factors and gene are expressed, such as Pax-9, Activin-betaA
65
What happens during the cap stage of tooth development?
Formation of tooth germ as enamel organ forms into a cap shape that surrounds inside mass of dental papilla (ball of condos ectomesenchymal cells), with an outside mass of dental follicle (sac) Proliferation, differentiation and morphogenisis
66
Dental Papilla?
* Arises from ectomesenchyme
* a condensed zone of cells beneath the enamel organ, separated by basement membrane
* it will from dentin and pulp
67
dental follicle?
less condensed than dental papilla
| -surrounding ectomesenchymal cells give rise to cememntum and periodontal ligament
68
Dental Organ?
aka "Tooth Germ"
* Enamel Organ
* Dental Papilla
* Dental Follicle
69
Enamel knot?
They are cluster of non dividing epithelial cells visible in section of molar cap stage tooth germs. Each tooth germ has a single primary enamel knot and secondary enamel knots at the tips of the future cusps in the premolar and molars at the cap stage
70
Bell Stage
- continued growth
- where enamel organ resembles a bell with deepening of epithelium over the dental papilla
- continuation of histodifferentiation: ameloblasts and odontoblasts are defined
- beginning of morphodifferentiation: tooth and crown assumes final shape
71
Often called Zone of Reflexion?
aka - Cervical loop
Area where the inner and outer enamel epithelia meet at the rim of the enamel organ.
72
Epithelial pearls
Or cell rests of Serrez
When leftover dental lamina persist
May form eruption cysts that delay tooth eruption
May be activated to form supernumerary teeth.
73
Tooth histodifferentiation
- inner enamel epithelial cells differentiate into preameloblasts.
dental papilla cells (undifferentiated ectomesenchymal cells)- change into odontoblasts
Happens in cap to early bell stage- they produce the matrix that later mineralizes.
Differentiation of the ameloblasts and the odontoblasts cannot occur without the other - reciprocal induction
74
Root formation?
Begins once the crown outline is complete. Begins at the point where outer enamel epithelium and inner enamel epithelium meet (CERVICAL LOOP). The proliferate from the enamel organ and form a double layer of cells known as Hertwig's Epithelial root sheath.
75
What is the Hertwig's Epithelial Root Sheath?
Formed from the fusion of the IEE and OEE at the cervical loop, it encircles the dental papilla underneath the follicle. It induces differentiation of Odontoblasts to for Radicular Dentin without enamel. The Rim of the sheath forms the epithelial diaphragm that encloses the primary apical foramen.
76
4 layers of enamel organ?
outer dental epith.
stellate reticulum
stratum intermedium
inner dental epith.
77
Types of Bone Formation
1. Intramembranous
Bone forms directly from mesenchyme , don’t need cartilage template
Skull, mandible, clavicle
2. Endochondral
Bone replaces a highline cartilage template
Base of the skull, vertebrae, limbs
78
periosteum?
connective tissue membrane, which has two layers. Outer layer consists of a dense, irregular connective tissue fibrous layer . Inner layer, consists of bone cells, their precursors and rich microvascular supply osteogenic layer .
79
How can you check if there is osteoblastic activity in a fracture line?
scintigraphy with labelled Bril protein or immunohistochemical stain
80
Endochrondral bone formation occurs where in the mandible?
At the articular extremity of the mandible.
81
skull cambium?
is the osteogenic (outer layer) layer of the suture. The inner layer is the capsule
82
Bone turnover rate per year in growing animals
30-100%
83
What is the turnover rate for trabecular bone vs cortical?
Cortical bone is remodeled between 2%and 5% each year. trabecular bone turns over at about 15% per year.
84
Enamel thickness dog (range)
0.1- 1 mm dog
85
What are the two steps of amelogenesis?
1. A partially mineralized matrix is produced (~30%)
| 2. An influx of additional mineral with removal of organic material and water to attain greater than 96% mineral content
86
What are the 7 phases of amelogenesis?
1) Morphogenic
2) Differentiation
3) presecretory
4) Secretory (formative stage)
5) Maturation (ruffle ended)
6) Maturation (smooth ended)
```
7) Protective
other subdivision is
a) presecretory
b) secretory
c) maturation
```
87
What are the three stages of amelogenesis?
Presecretory
Secretory
Maturation
88
Tomes Process
where the ameloblasts produce the enamel matrix. It is the secretory surface of the ameloblast that faces the DEJ. It forms the interrod and rod configuration.
89
How is the pH controlled during enamel formation?
The pH is is believed to be controlled by the ameloblasts involving carbonic anhydrases to generate local bicarbonate, chloride ion exchangers.
90
Striae of Retzius
incremental growth lines or weekly rhythm of enamel production. They are visible in the light microscope and appear as concentric dark lines.
91
Enamel tufts?
small areas of hypocalcification at DEJ extend a 1/4 to 1/3 the way toward the surfaces no known clinical significance commonly found on histology
92
Enamel Lamellae?
thin-leaf like unmineralised structures which are arranged within the enamel and extend vertically. Filled with organic debris from oral cavity, trapped enamel organ, CT surrounding the developing tooth.
NOT A CRACK - crack would have no organic material
primary: prior to eruption
secondary: arise as a result of occlusal trauma
93
Perikymata
- surface enamel
- end points of striae of retzius
- circumferentialy horizontal lines
- shallow furrows
- pellicle
94
Dentin made of?
70% inorganic hydroxyapatite crystals
20% organic collagen fibers and protein
10% water
95
Organic components of dentin?
1. Type I Collagen 90% (and Type III and V)
2. GAGs (acid mucopolysaccharides)
3. Phosphorin
4. Dentin phosphoprotein
5. Dentin glycoprotein
6. Dentin-matrix protein-1
7. Osteocalcin, bone sialprotein, osteopontin.
96
Mantle Dentin
- first primary dentin formed
- interdigitates with enamel to create scalloped DEJ
- layer approx. 150 um thick
- slightly less mineralized than rest of dentin
- is mineralizes different from the primary dentin and is different in the structural interrelation between the collagenous and noncollagenous matrix components
97
Secondary dentin is developed when?
Secondary dentin develops after root formation has been completed. Two months after tooth eruption.
98
Tertiary dentinal tubule structure is different from secondary, how?
Tertiary tubules may have continuous tubules with those of the secondary dentin, tubules sparse in number and irregulary arranged or no tubules at all.
99
When does dentin formation begin?
* during the early bell stage
* its the coronal dentin that is formed from root apex down slope cusps
* root dentin formed later
100
How is differentiation of odontoblasts from the dental papilla occur?
Expression of signalin molecules and growth factors in the cells of the inner enamel epithelium IEE.
101
What are Korff's fibers?
Large collagen fibrils (0.1-02mm) found at the beginning of dentin formation.
They consist of collagen type III. Later they produce collagen type I.
102
Tomes' fiber?
-cellular process from an odontoblast
103
Mineralization patterns of dentin
* Linear
| * Globular: radial pattern
104
Differentiation of root odontoblasts is initiate by what?
The epithelial cells of Hertwig's root sheath
105
when do you know when primary dentin becomes secondary dentin?
there is an obvious change in direction and deposition slows down. There is a demarcation line and less regular organization of dentinal tubules.
106
Granular layer (or granular layer of Tomes)
When a thin, calcified section of root is studied under transmitted light, a granular-appearing layer of dentin is seen underlying the cementum that covers the root.
107
What are the four layers (outer to inner) of the central zone or pulp proper:
1. Odontoblastic layer
2. Cell free of Weil
3. Cell rich
4. Pulpal core - except for location, same as cell-rich.
108
Odontoblast phenotype throughout the tooth
Odontoblasts are larger at the crown than at the root.
109
What is the most common cell in the pulp and where are they located?
Fibroblasts; cell-rich layer
110
Cells of the pulp
- Fibroblasts = most abundant; fuction to form and maintain pulp matrix (collagen and ground substance)
- Odontoblasts - lay down dentin
- Lymphocytes = T lymphocytes and small amounts of B lymphocytes
- Neutrophils and eosinophils, only present with inflammation.
- Dendritic cells = found in odontoblastic layer; imunosurveillance; capture and present foreign antigen to T cells; increase number in carious teeth; cell processes between odontoblasts
- Undifferentiated mesenchymal cells - line apical foramen and PDL
111
the subodontoblastic nerve plexus of raschkow is located in which zone of dental pulp
cell free zone (zone of Wiel)
112
What happens to the pulp nerves as one ages
Loss and a degeneration of myelinate and unmyelinated axons that correlates with an age-related reduction in sensitivity. More sclerotic dentin is also formed, which reduced the sensitivity as well.
113
Types of Cementum
* Acellular cementum - contains no cementocyte within the mineralized tissue. Covers the cervical 1/3-1/2 of the tooth
* Cellular cementum - contains cementocytes within its mineralized tissue. Covers the apical half of the root.
114
Composition of Cementum
50-55% organic (fibers (collagen and noncollagenous proteins) and cells)
45-50% inorganic (hydroxyapetite crystals) -- less calcified than dentin and enamel
115
What type of collagen is most commonly found in the periodontal ligament besides type I
Type XII collagen
116
Name the noncollagenous proteins in the cementum
1) Alkaline phosphatase
2) Bone sialoprotein
3) Dentin matrix protein 1
4) Dentin sialoprotein
5) Fibronectin
6) Osteocalcin, osteopontin & osteonectin
7) Proteoglycans, proteolipids
8) tenascin
9) Several growth factors
117
precursors of cementoblasts and periodontal ligament fibroblast
The longstanding view is that they derive from orm the dental follicle and that factors within that region or environment regulates there differentiation.
118
What are examples of growth factors associated with cementogenesis?
TGF
PDGF
FGF
BMP
119
Where is acellular extrinsic fiber cementum located?
Cervical margin and 2/3 of the root
120
What is the function and location of cellular intrinsic fiber cementum?
Located on the middle to apical thirds and furcations
| Functions in adaptation and repair
121
acellular afibrillar cementum
limited to CEJ - lacks collagen - no attachment
122
what cellular origin is the periodontium
ectomesenchymal
123
What are the two stage of cementum development
1. Pre-functional (occurs throughout root development)
| 2. Functional stage (starts when tooth is in occlusion)
124
What are the functional characteristics of acellular cementum
provides attachment for the tooth
125
What are the functional characteristics of cellular cementum
an adaptive role in response to tooth wear and movement and is associated with repair
126
what is the approximate hydroapatite percentage of cementum
45-50%
127
What is the predominant collagen of cementum
Type I collagen (90% of the organic components)
128
What collagen is found is high concentrations during development and during repair and regeneration in the periodontium
Type III collagen
129
What collagen is found in high concentration in the PDL
Type XII collagen
130
name non-collagenous protein in the cementum
1. alkaline phosphotase
2. bone sialoprotein
3. dentin matrix protein 1
4. dentin sialoprotein
5. fibronectin
6. osteocalcin
7. osteonectin
8. osteopontin
9. proteoglycans.
10. tenascin
131
What is the thickness of the cementum
50 um at the cervical area and 200 um more apically
132
What is bundle bone
the bone directly lining the alveolar socket
133
What is the width of the PDL
Range is 0.15 - 0.38 mm, with the thinnest point at the middle third of the root. The width decreases with age
134
What is Vicryl
Polyglactin 910. A copolymer of glycol and lactic acid. Absorbed by hydrolysis
135
What is PDS suture
Polydioxanone a polymer of the monomer paradioxanone
136
What is Monocryl suture
Poliglecaprone 25 a copolymer. Completely hydrolysed by 90 days
137
What is Ethilon
Polyamide, Nylon
138
Which suture is better Polyamide or Polypropylene
Polypropylene. Loses no strength, has better knot security, elasticity
139
What is the most commonly used needle shape in oromaxillofacial surgery
3/8-circle needle
140
how much is the needle strength increased by making it a reverse-cutting needle
32% compared to a conventional cutting.
141
What is bone wax
Beeswax that has been purified.
142
What is Gelfoam
a porous matrix gelatin sponge from hydrolysed pork skin
143
How much can Surgical (oxidised cellulose) swell
135%
144
What is the reported mandibular fracture occurrence at the first molar
41-47 %
145
What is the wavelength of UV light
100-400 nm
146
What is the wavelength of visible light
400-750 nm
147
What is the wavelength of infrared light
>750 nm
148
Is the light emitted by laser monochromatic or polychromatic
monochromatic (one wavelength)
149
Which nerve is the primary afferent nerve supplying the face and oral cavity
Trigeminal nerve (V)
150
Which are the primary nociceptive nerve fibers
Myelinated A-delta and unmyelinated C-fibers
151
Which are the primary nerve fibers to sense vibration and proprioception
Myelinated A-beta fibers
152
A-beta fibers
- myelinated
- rapid conduction
- vibration and proprioception
- can transmit pain when chronic inflammation is present
153
A-delta fibers
- Lightly myelinated
- Intermediate conduction velocity
- Sharp pricking sensation
- End in dentinal tubules
154
C-fibers
- Slower conduction
- transmit a dull, aching, burning sensation
- Respond to mechanical, thermal and chemical stimuli.
- Further sensitized by inflammation
- May become responsive to sympathetic nerve stimulation if chronic inflammation present
155
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The dental pulp is richly innervated by both myelinated (A-fibers, mostly A delta-type) and unmyelinated (C-fibers) axons. A-fibers seem to be responsible for the sensitivity of dentin. They respond to stimuli that induce sharp pain in human teeth, for example, drilling of dentin and drying of dentin with air blasts. C-fibers are activated only when the stimuli used reach the pulp proper. They respond to intense heating. In human teeth, dull pain is induced at a temperature level corresponding to the heat thresholds of intradental C-fibers. The other functional characteristics of C-fibers indicate that they may play a role in the mediation of the dull pain connected with pulpal inflammation
156
Source of odontogenic toothache
- The primary nociceptors of the pulp that respond to inflammation are C fibers.
- They typically conduct pain associated with tissue damage, and respond with a threshold manner that can be termed “all or nothing”.
- If sensitized by inflammation, threshold sinks
157
Convergence in tooth pain
- multiple afferent fibers of nontrigeminal origin can converge and synapse onto trigeminal projection neurons that result in the clinical finding that pain radiates beyond an area of tissue injury, or why pain appears to be associated with a site other than the injured area
- in the cat, 74% of neurons showed convergence from multiple tooth pulps
- Localizing tests (hot or cold stimulation stimulate A-delta fibers) can be used prior to treatment
158
Periradicular pain
- Triggered by mechanoreceptors
- These are especially numerous in the apical 1/3 of the periodontal ligament
- dull, aching, or throbbing pain
- should respond to local anesthesia
159
American National Standards Institute
| numbers for K-files
#28
160
American National Standards Institute
| numbers for H-files
#58
161
American National Standards Institute
| numbers for barbed broaches/rasps
#63
162
American National Standards Institute
| numbers for condensers, pluggers, and spreaders
#71
163
American National Standards Institute
| numbers for gutta percha cones
#78
164
6 groups of endo instruments:
| Group 1
- Manually operated instruments
- K-files, H-files, barbed broaches
- clean the canal
165
6 groups of endo instruments:
| Group 2
- Low-speed instruments with latch-type attachment
- Gates-Glydden & Peeso reamers
- enlargen the canal
166
6 groups of endo instruments:
| Group 3
- Rotary instruments
- Lightspeed, etc.
- for canal preparation
167
6 groups of endo instruments:
| Group 4
Engine-driven 3D-adjusting file
- One file is used throughout the procedure, and gradually enlarges/cleans the canal, via in-out vibrations while the canal is continuously irrigated.
168
6 groups of endo instruments:
| Group 5
- Engine-driven reciprocating instruments
- Endo-eze reciprocating files
- 3000 quarter turns per minute created
169
6 groups of endo instruments:
| Group 6
Sonic and ultraconic instruments
170
Components of a file
taper = increase in file diameter along it’s working surface
flute = groove in the working surface used to remove soft tissue/dentin from walls of the canal.
leading/cutting edge = the surface with the greatest diameter that follows the groove as it rotates
