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الكلية كلية طب الاسنان
القسم ترميم ومعالجة الاسنان
المرحلة 4
أستاذ المادة احمد غانم مهدي الهلال
4/17/2011 6:20:11 PM
Restorative dentistry and pulpal health
Pulp:
is a viscous connective tissue of collagen fibers and ground substance supporting the vital cellular, vascular, and nerve structures of the tooth. It contains blood vessels and nerves that enter through the apical foramen.
Effect of operative procedures on the pulp:
The commonly used operative procedures endanger the pulp more than the disease process, this process called dentist induced pulpitis.
1. Effect of local anesthesia on pulp tissue:
Vasoconstrictors in LA increase and prolong the effect of anesthesia by decreasing the blood flow in the area, and this may lead to increase the concentration of irritants within the pulp.
2. Effect of cutting procedures:
When the dentin is extensively removed during operative procedures may lead to pulp trauma especially with high speed turbines and insufficient water cooling.
The immediate pulp reaction is the disturbance of odontoblastic cells beneath the cutted tubules followed by stripping of odontoblastic layer from predentine then establishment of acute inflammatory reaction. Usually it will resolve by repair process with subsequent reparative dentine formation, this healing depend on the following factors:
a. The depth of cavity: the deeper the cavity the more damage to the pulp.
b. speed of rotation: depends on weather there is a water cooling or not, speeds between 3000-30000 rpm are more damaging specially if there is no effective water cooling.
c. Frictional heat: the heat production inside the pulp is very dangerous, the amount of heat produced depends on speed of rotation, size and shape of cutting instruments, length of time of contact with the dentin, amount of pressure exerted on handpeice and weather the water cooling is used or not. The water coolants are more effective than air cooling , and for the water to be effective it must have sufficient pressure to penetrate the area of turbulence and should be delivered directly at the point of contact between the bur and the tooth.
d. rebound pressure duo to vibration: increasing the speed of rotation not only increase the heat production but also increase in vibration which affect the pulp, these vibration may affect the odontoblastic cells and may cause displacement of these cells on the other side of the pulp.
e. Extensiveness of preparation: the pulp damage is roughly proportional to the amount of tooth structure removed.
f. The use of pins: the insertion of pins increases the danger of dental fractures or unnoticed pulp exposure or perforation trough periodontal ligament, also the cementation of pins with irritant materials cause more damage to the pulp.
g. Nature of cutting instruments: dull instruments and burs need more pressure which lead to more heat generation and vibration.
h. dryness of dentin: dryness of cutted dentin with a jet of air produces a rapid outward movement of dentinal fluid, this will result in stimulation of sensory nerve fibers and may draw the odontoblasts up into the tubules resulting in cell death.
3. The effect during lining procedures:
Some materials used in conservative dentistry may produce irritation to the pulp (chemical, acidity, absorption of water during setting), so in deep cavities we should use non irritant lining materials such as Ca(OH)2 or ZOE beneath the lining materials.
4. The effect during filling procedures:
We must insure the following:
1. Correct placement of retainer, band and retainer.
2. Correct placement of filling materials to avoid microleakage and development of secondary caries.
3. Correct carving and checking of high spots.
4. Avoid heat generation during amalgam polishing.
5. Placing a good non irritant lining material when we plan to place an irritant filling material such as composite.
5. Effect after restoration.
Irradiation irritants to pulp:
The pulps of human teeth are affected in patients exposed to deep radiation therapy (malignancy), with time the odontoblasts and other pulp cells become necrotic. The salivary gland also affected resulting in decreasing the salivary flow (xerostomia).
Clinically important features of dental pulp:
? With age the pulp becomes less cellular.
?
The volume of pulp chamber decreases with increasing the age because of the continuous deposition of dentin, in some cases the pulp chamber completely obliterated.
? With age there is increase in the calcification in dental pulp.
? With age there is increased possibility of encountering pulp stones.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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