Bài giảng nha khoa Dentin pulp complex

Trang 2 INTRODUCTIONDentin and dental pulp are differences in structure and composition:• Dentin is a hard tissue• Dental pulp is a soft tissueDentin and dental pulp have a common embryo

DENTIN-PULP COMPLEX:

STRUCTURAL BIOLOGY AND ITS APPLICATION

IN RESTORATIVE DENTISTRY

People’s Teacher

Prof Hoàng Tử Hùng, DDS, PhD E: tuhung.hoang@gmail.com

Dentin and dental pulp are differences in structure and composition:

reactions in one of the tissues will also affect the other

Anything that affects dentin will affect the pulp and vice versa

🡪 The concept of a dentin-pulp complex [or organ] is, therefore, well founded and

generally recognized

Most pulpal cells are considered to be of an undifferentiated or immature type

into specialized cells, e.g., odontoblast-like cells

CHARACTERISTICS OF DENTAL-PULP TISSUE

Pulpal physiology under normal conditions, and especially during inflammatory

vessels of the pulp, the interstitial fluid, and nerves Macrophages are seen in the normal pulp, and their numbers increase in association with pulpal injury

The interstitial fluid surrounds the morphologic elements is an important

intermediary link between cells, blood plasma, and lymph fluid The interstitial

fluid of the pulp and the dentinal tubules form a continuum that extends from the dentinoenamel and cementodentinal junctions to the central parts of the soft

connective tissue in the pulp

The structural characteristics of blood vessels in the pulp include:

- thin walled,

- discontinuities in the endothelial walls, and

- fenestration of capillaries

Characteristics of the blood vessels have a

physiologic function: they facilitate the exchange of nutrients and waste products between the

interstitial tissue fluid and the blood plasma

This exchange is particularly important at the time

of injury, including operative procedures, trauma, and caries lesions affecting the pulp.

Lymphatic vessels transport fluid out of the pulp and play a role in maintaining the fluid balance.

Typical dentin pain is short-lasting, sharp, and may be described as lancinating.

DENTIN SENSITIVITY

All stimuli: pressure, trauma, heat, cold and chemical irritation etc are perceived as

Cold stimuli were found to be more painful than hot stimuli, probably because of

when cold is applied

occurs

Three mechanisms have been proposed to explain

dentin sensitivity:

1- the direct innervation theory: dentin is

innervated directly: dentin contains nerve endings

that respond when it is stimulated

dentin fluid movement to occur within the tubule when a stimulus is applied, a

movement registered by pulpal free nerve endings close to the dentin

receptors and are coupled to nerves in the pulp

odontoblast-neuron signal transduction

Any reduction in conductance will reduce the

dentin sensitivity:

- by occlusion of the tubules by mineral

precipitation, adsorption of organic materials in

the tubules, or

- by hypermineralization of the surface dentin

The formation of peritubular dentin at the

interface between primary or secondary dentin

and tertiary dentin will also reduce the

conductivity of dentin fluid.

Agents that prevent the contents of the tubules

flux across exposed dentin may eliminate or

reduce dentin pain This is applied in treatment

of dentinal hypersensitive products and the

contemporary dentin adhesive techniques

Opened dentinal tubules (Dt) and naturally desensitized erea: the Dt are closed

With pulpal inflammation, the pressure can rise to 35 mmHg or higher, the pulp almost totally enclosed within a hard tissue chamber, can quickly suffer

irreversible damage

Interstitial fluid and Interstitial fluid pressure

The interstitial fluid pressure in the pulp is

relatively high, and it plays a role in the

sudden pain experienced when a cavity

preparation reaches unaffected dentin

The pressure: 8 – 15 mmHg

AGING TOOTH AND DENTIN-PULP COMPLEX

The dentin-pulp complex undergoes regressive change with time

- Reduction in the number of blood vessels

within the coronal pulp

Narowing of the pulp cavity, Translucent dentin, Depositon of cementum

The fiber-poor and cell-rich state is a characteristic feature of

the young pulp, but it changes with age:

tertiary dentin]

gradual reduction of the tubule diameter and event

complete closure

Age-related changes in the pulp nerves and blood vessels accompany the

cellular changes:

number of cells is low

differentiate into other cell types or to take part in reparative processes in the

Tissue in the central part of the pulp in a newly erupted tooth: the large number of cells (left) and a 67-year-old individual: few cells are found

BV = Blood vessel (x350 )

Physiologic aging changes of the dentin-pulp complex can be troubled or stopped

by chronic pathological processes: caries, pulpitis, trauma, and especially pulpal necrosis

An aging pulp tissue loses some of its functional capacity:

–phosphorus They may be singular or multiple and found usually at orifice of

the pulp cavity

Age changes in the pulp-dentin complex render it more resistant to environmental injury:

This close association includes reactions to caries and common clinical

procedures such as cavity or crown preparations and restorative procedures

DENTIN “WOULD” and PULPAL IRRITATION

≈ 30% volume of dentin is taken up by cytoplasm of the

odontoblastic processes and their lateral branches

≈ 30 000 – 40 000 odontoblastic processes are cut for

Crown preparation, which end in the peripheral

zone of dentin, open ≈ 15 000 tubules/1 mm²

The danger is reduced with aging tooth because of

secondary dentin formation, reducing size of pulp chamber

and sclerosis of the dentin

All components of the dental pulp, including the cells, blood and lymphatic vessels,

procedures

DENTIN-PULP COMPLEX RESPONSE TO RESTORATIVE PROCEDURE

A biologic approach to restorative dentistry requires knowledge of the normal

structure and physiology of dentin and pulp, including age-related changes

Hydrodynamic effects and fluid shifts are, therefore, important under normal and

pathologic conditions and they will affect the pulp-dentin organ.

The mere cutting of dentin, as it occurs during cavity and crown preparations, will result

in several of reactions in the pulp and the dentin.

Pulpal pain is characteristically pulsating, long-lasting, and of variable severity, sometimes excruciating It is also affected by changes in blood pressure to the bead

PULPAL

IRRITATIONS

Every dentin intervention that involves opening of dental tubules brings a

irreversible

The type, duration, and severity of the pulp reaction will vary depending on the

- chemically, materials that use for dentin and enamel etching [acidic

solutions]

- bonding agent

- filling material

Protection of the vitality of the pulp is paramount goal of all restorative procedures

Agents that prevent the dentin tubular contents flux across exposed dentin may eliminate

or reduce dentin pain

A smear layer is an adherent layer of debris on

tooth surfaces when they are cut with rotary or

hand instruments

The orifices of the dentin tubules are

which may extend into the tubule to a depth of

1–10 mm These smear plugs are contiguous

with the smear layer

in which resin infiltrate into smear layer and smear

With the infiltration of resin into smear layer, the

hybrid layer is created on dentin surface and resin tags extend into the

dentinal tubules, attaching the resin tags to tubules walls

Dentin etched with 37.5%

phosphoric acid At the dentin surface and tubule walls, the inorganic component of dentin smear and peritubular dentin has been dissolved, resulting in the typical funneling of the tubule orifice

A smear layer of ≈ 1 μm

covers the entire dentin

surface, and a smear plug ,

extending 1 -10 μm into the

dentin tubule, occludes the

tubule’s orifice.

MECHANISM OF DENTIN BONDING

PULPAL IRRITATIONS (cont’d.)

the stream of coolant (spray) should be reaching the

site

Autopolymerization of acrylic resin in situ

[temporary crown, anterior jig…] can rise the

temperature in the pulp chamber to 75ºC

In the worst case, the odontoblastic layer becomes

devitalized over a large area

Temperature increases greater than 10ºC cause precipitation of protein and

irreversible cell and tissue necrosis

From a functional point of view and especially in relation to restorative dentistry,

dentin and pulp are integrated to an extent that they should be regarded as

a complex

structure and physiology of dentin and pulp, including age-related changes

Summary

Protection of the vitality of the pulp is paramount goal of conservative dentistry All restorative procedures in a vital tooth should prevent the damage to the

dentin-pulp complex

SUCGESTED READING

- Shibukawa Y, Sato M, Kimura M, et al.: Odontoblast as sensory receptors:

transient receptor potential channels, pannexin-1, and ionotropic ATP receptors mediate intercellular odontoblastneuron signal transduction, Pflugers Arch, 2014

- B.K.B Berkovitz, G.R Holland, B.J Moxham: Oral Anatomy, Histology and

Embryology, Mosby, 2002