clinical significance lec

71問 • 1年前

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essential for the proper esthetics of the smile, facial soft tissue contours (e.g. lip support) and speech (phonetics)

Incisors

not only serve as important guides in occlusion because of their anchorage and position in the dental arches but also play a crucial role (along with the incisors) in the esthetics of smile and lip support

canines

important in maintaining the vertical dimension

Premolars and molars

it is considered as a one tissue because the head of the dentinal tubules (odontoblasts) lies along the periphery of the pulp

Pulp-dentin complex:

Ameloblasts have short extensions toward the dentinoenamel junction (DEJ);

tomes processes

Enamel is formed by cells called ameloblasts, which originate from the embryonic germ layer known as

ectoderm

incisal ridges and incisors

2mm

cusps and premolars

2.3 to 2.5mm

cusps of molars

2.5 to 3mm

Hypomineralized (decreased minimal component of the enamel rods) structures of enamel rods and interrod substance

ENAMEL TUFTS

Thin, leaf-like faults between enamel rod groups that extend from the enamel surface to the dentin

ENAMEL LAMELLAE

Odontoblastic processes that cross the DEJ into the dentin; pain receptors

ENAMEL SPINDLES

Successive apposition (growth and development in the layering of the enamel) of enamel in increments, similar to growth rings

STRIAE OF RETZIUS

Series of alternating grooves formed by the incomplete circles of the striae of Retzius in vertical sections of teeth

IMBRICATION LINES OF PICKERILL

Elevations in between the imbrication lines of Pickerill

PERYKIMATA

When X-ray passes through an object with hydroxyapatite,

object will absorb all the energy, color white

If there is hydroxyapatite

radiopaque, enamel, dentin, cementum, alveolar bone

If there is no hydroxyapatite

Radiolucent, pulp, palp canal, pulpal horn, radicular pulp, apical foramen, periodontal ligament and space, gingival tissues

head of the dentinal tubules

odontoblasts

have short extensions toward the dentinoenamel junction (DEJ); these are termed tomes processes

Ameloblasts

covers the anatomic crown of the tooth and varies in thickness in different areas

Enamel

straight in the occlusal area and it curls as it approaches the DEJ and there is overlapping. It is hard for the acid to penetrate because of its hydroxyapatite content

Enamel

The best time to have a fluoride topical application is when the teeth are in mixed dentition

(6-13 years old)

Enamel rods cervical of permanent teeth oriented

apically

Rods temporry teeth

occlusally

Enamel

95% to 98% inorganic hydroxyapatite crystals, 1-2% organic, 4-12% by volume soluble to acids, Incapable of repair or regeneration, high elastic modulus and low tensile strength, very rigid and brittle

Dentin

highly compressive tissue that acts as a cushion for the enamel

Dentin and pulp tissues are specialized connective tissues of

mesodermal origin

small canals that extend across the entire width of dentin, from the dentinoenamel junction to the pulp

dentinal tubules

Formed from the dental papilla of the tooth bud

pulp dentin complex

begin dentin formation immediately before enamel formation by the ameloblasts

odontoblasts

most sensitive part of the tooth

DEJ

Each tubule contains the cytoplasmic cell process ______ of an odontoblast

Tomes fiber

cavity liner that lines the pulp

Calcium hydroxide

upon placement of the calcium hydroxide, this will sterilized those carious lesions of the exposed pulp

Carious lesions adjacent to the pulp

formed by replacement odontoblasts (termed secondary odontoblasts) in response to moderate-level irritants,

Reparative/tertiary dentin

Attrition, Abrasion, Erosion, Trauma, Moderate-rate dentinal caries, Some operative procedures

dead tracts

age-related change associated with the death of odontoblasts, sealed off at the pulpal surface by reparative dentin, affected odontoblastic processes may die with the associated odontoblasts

the tubules instead of being empty are now filled with calcified material

Sclerotic dentin

Hydroxyapatite Enamel

smear layer

natural bandage over the cut dentinal surface because it occludes many of the dentinal tubules with debris called smear plugs, good protective barrier, it has a relatively weak attachment to the dentin and is subject to dissolution by acids, only a few micrometers thick and is composed of denatured collagen, hydroxyapatite, and other cutting debris

The smear layer serves as a natural bandage over the cut dentinal surface because it occludes many of the dentinal tubules with debris called

smear plugs

hydrodynamic theory

most accepted theory of pain transmission, pain transmission through small, rapid movements of fluid that occur within the dentinal tubules

Histodifferentiation stage

structures are formed, dental enamel organ, dental papilla, dental follicle, IDE, ODE, enamel navel

Morphodifferentaition stage

size and shape of the teeth, microdontia, macrodontia, Membrana Preformativa + odontoblast =DEJ

Apposition stage

thickness of the enamel, dentin , cementum, pulp, bone, Dentin form, then calcified ( layering of calcification), Enamel forms till cusp, edge then calcification starts ( primary, secondary )

Calcification stage

deposition of calcium salts

Initiation Stage

number of teeth

Enamel rods that fail to possess a dentin base because of caries or improper preparation design are

easily fractured away from neighboring rods.

The odontoblasts begin dentin formation immediately ___ by the ameloblasts

before enamel formation

Each dentinal tubule is lined with a layer of ____, which is much more mineralized than the surrounding intertubular dentin

peritubular dentin

connects tubules together

Intertubular dentin

outermost covering of the tubule

Peritubular dentin

comp. strength

266 MPa (40000 PSI)

(mod of elasticity); This flexibility helps support • the more brittle, nonresilient enamel.

1.67 X 106 PSI

tensile strength; The tensile strength of dentin is which is less than cortical bone and approximately one half that of enamel.

40 MPa (6000 PSI)

dentin is usually distinguishedfrom enamel by:

color, reflectance, hardness, sound

Dentin must be treated with great care during restorative procedures to minimize damage to

dentin, pulp

Embedded in the cementum:

cementocytes

Cells that causes resorption of the cementum

cementoclasts

center of the pulp

pulp horn

If pain disappears 10-15 seconds after removal of irritant, resolution by means of immediate restoration is possible

reversible pulpitis

If pain becomes constant and of longer duration

irreversible pulpitis

Pulp forming cell

fibroblast

there are areas that are under stimulated and will produced a flabby, red, inflamed gingiva

Overcontour

there are tissues that are overstimulated

Undercontour

HEIGHT OF CONTOUR

Contacts with the proximal surfaces of the adjacent teeth, which prevents food impaction, Adequate embrasure space gingivally of the contacts for the gingival tissue, supporting bone, blood vessels, and nerves that serve the supporting structures

PROXIMAL CONTACT AREAS

promote normal healthy interdental papillae, Improper contacts can result in food impaction between the teeth, producing periodontal disease, carious lesions, and possible movement of the teeth, retention of food is objectionable by its physical presence and by the halitosis that results from food decomposition, Proximal contacts and interdigitation of the teeth through occlusal contacts stabilizes and maintains the integrity of the dental arches

PHYSIOLOGY OF TOOTH FORMS 4 Main Functions

Mastication, Speech, Esthetics, Protection of supporting tissues

Parts of the periodontium

alveolar bone, supporting alveolar bone, alveolar bone proper or lamina dura, gingiva, cementum, PDL

Coronal and radicular pulp

pulp horns, apical foramen, accessory canals

Sporeformers

Tameyra Stefani Al-Suhairy · 44問 · 1年前

Sporeformers