PROGRAMAS DE ATENCIÓN AL JUEGO PATOLÓGICO Y OTRAS ADICCIONES COMPORTAMENTALES (RED DE JUEGO DE EXTREMADURA)

Periradicular tissue consists of cementum, periodontal ligament and alveolar bone.

Cementum

Cementum can be defined as hard, avascular connective tissue that covers the roots of the teeth (Fig. 2.31). It is light yellow in color and can be differentiated from enamel by its lack of luster and darker hue. It is very permeable to dyes and chemical agents, from the pulp canal and the external root surface.

Types

There are two main types of root cementum 1. Acellular (Primary)

2. Cellular (Secondary) Acellular Cementum

1. Covers the cervical third of the root

2. Formed before the tooth reaches the occlusal plane.

3. As the name indicated, it does not contain cells.

4. Thickness is in the range 30-230 μm.

5. Abundance of sharpey’s fibers.

6. Main function is anchorage.

Cellular Cementum

1. Formed after the tooth reaches the occlusal plane.

2. It contains cells.

3. Less calcified than acellular cementum.

4. Sharpey’s fibers are present in lesser number as compared to acellular cementum.

5. Mainly found in apical third and interradicular region 6. Main function is adaptation.

Periodontal Ligament

Periodontal ligament is a unique structure as it forms a link between the alveolar bone and the cementum. It is continuous with the connective tissue of the gingiva and communicates with the marrow spaces through vascular channels in the bone.

Periodontal ligament houses the fibers, cells and other structural elements like blood vessels and nerves.

The periodontal ligament comprises of the following components

I. Periodontal fibers II. Cells

III. Blood vessels IV. Nerves

Periodontal Fibers

The most important component of periodontal ligament is principal fibers. These fibers are composed mainly of collagen type I while reticular fibers are collagen type III. The principal fibers are present in six arrangements (Fig. 2.32).

Horizontal Group

These fibers are arranged horizontally emerging form the alveolar bone and attached to the root cementum.

Alveolar Crest Group

These fibers arise from the alveolar crest in fan like manner and attach to the root cementum. These fibers prevent the extrusion of the tooth.

Oblique Fibers

These fibers make the largest group in the periodontal ligament.

They extend from cementum to bone obliquely. They bear the occlusal forces and transmit them to alveolar bone.

Fig. 2.31: Diagram showing periradicular tissue

21

Pulp and Periradicular Tissue

Transeptal Fibers

These fibers run from the cementum of one tooth to the cementum of another tooth crossing over the alveolar crest.

Apical Fibers

These fibers are present around the root apex.

Interradicular Fibers

Present in furcation areas of multirooted teeth.

Apart from the principal fibers, oxytalan and elastic fibers are also present.

Cells

The cells present in periodontal ligament are a. Fibroblast

b. Macrophages c. Mast cells d. Neutrophils e. Lymphocytes f. Plasma cells

g. Epithelial cells rests of Mallassez.

Nerve Fibers

The nerve fibers present in periodontal ligament, is either of myelinated or non-myelinated type.

Blood Vessels

The periodontal ligament receives blood supply form the gingival, alveolar and apical vessels.

Functions Supportive

Tooth is supported and suspended in alveolar socket with the help of periodontal ligament.

Nutritive

Periodontal ligament has very rich blood supply. So, it supplies nutrients to adjoining structures such as cementum, bone and gingiva by way of blood vessels. It also provides lymphatic drainage.

Protective

These fibers perform the function of protection absorbing the occlusal forces and transmitting to the underlying alveolar bone.

Formative

The cells of PDL help in formation of surrounding structures such as alveolar bone and cementum.

Resorptive

The resorptive function is also accomplished with the cells like osteoclasts, cementoclasts and fibroblasts provided by periodontal ligament.

Alveolar Bone (Fig. 2.33)

Bone is specialized connective tissue which comprises of inorganic phases that is very well designed for its role as load bearing structure of the body.

Cells

Cells present in bone are:

a. Osteocytes b. Osteoblasts c. Osteoclasts

Intercellular Matrix

Bone consists of two third inorganic matter and one third organic matter. Inorganic matter is composed mainly of minerals calcium and phosphate along with hydroxyl apatite, carbonate, citrate etc. while organic matrix is composed mainly of collagen type I (90%).

Bone consists of two plates of compact bone separated by spongy bone in between. In some area there is no spongy bone. The spaces between trabeculae of spongy bone are filled with marrow which consists of hemopoietic tissue in early life and fatty tissue later in life. Bone is a dynamic tissue conti-nuously forming and resorbing in response to functional needs.

Both local as well as hormonal factors play an important role in metabolism of bone. In healthy conditions the crest of alveolar bone lies approximately 2-3 mm apical to the cemento-enamel junction but it comes to lie more apically in periodontal diseases. In periapical diseases, it gets resorbed easily.

QUESTION

Q. Write short notes on:

a. Zones of dental pulp b. Odontoblasts

c. Accessory and lateral canals d. Innervation of pulp e. Functions of pulp f. Age changes in the pulp

g. Pulp stones/denticles/pulpal calcifications

Fig. 2.33: Radiographic appearance of alveolar bone

22

Textbook of Endodontics

BIBLIOGRAPHY

1. Bernick S. Differences in nerve distribution between erupted and non-erupted human teeth. J Dent Res 1964;43:406.

2. Byers MR. The development of sensory innervations in dentine.

J Comp Neurol 1980;191:413.

3. Heverass KJ. Pulpal, microvascular, and tissue pressure. J Dent Res 1985;64:585.

4. Johnsen DC. Innervations of teeth: qualitative, quantitative and developmental assessment. J Dent Res 1985;64:555.

5. Kim S. Regulation of pulpal blood flow. J Dent Res 1983;64:590.

6. Linde A. The extracellular matrix of the dental pulp and dentin.

J Dent Res 1985;64:523.

7. Mjör IA. Dentin-predentin complex and its permeability:

pathology and treatment overview. J Dent Res 1985;64:621.

8. Närhi MVO. The characteristics of intradental sensory units and their responses to stimulation. J Dent Res 1985;64:564.

9. Olgart LM. The role of local factors in dentin and pulp in intradental pain mechanisms. J Dent Res 1985;64:572.

10. Pashley DH. Dentin-predentin complex and its permeability:

Physiologic overview. J Dent Res 1985;64:613.

11. Ruch JV. Odontoblast differentiation and the formation of odontoblas layer. J Dent Res 1985;64:489.

12. Thomas HF. The dentin-predentin complex and its permeability;

anatomical overview. J Dent Res 1985;64:607.

13. Veis A. The role of dental pulp—thoughts on the session on pulp repair processes. J Dent Res 1985;64:552.

14. Yamamura T. Differentiation of pulpal cells and inductive influences of various matrices with reference to pulpal wound healing. J Dent Res 1985;64:530.

Pathologies of

❑ Etiology of Pulpal Diseases

❑

❑

❑

❑

❑ Radiation Injury to Pulp

❑

❑❑

❑❑ Progression of Pulpal Pathologies

❑

❑

❑

❑

❑ Diagnostic Aids for Pulpal Pathology

❑

❑❑

❑

❑ Classification of Pulpal Pathologies

❑

❑

❑

❑

❑ Normal Pulp and Pulpitis

❑

❑❑ Reversible Pulpitis/Hyperemia/Hyperactive Pulpalgia

❑❑ Internal Resorption

❑

❑ Etiology of Periradicular Diseases

❑

❑

❑

❑

❑ Diagnosis of Periradicular Pathologies

❑

❑ Clinical Periapical Tests

❑

❑❑

❑❑ Classification of Periradicular Pathologies

❑

❑❑

❑❑ Acute Apical Periodontitis (AAP)

❑

❑❑

❑

❑ Acute Apical Abscess

❑

❑❑

❑

❑ Phoenix Abscess/Recrudescent Abscess

❑

❑ Chronic Alveolar Abscess

❑

❑

❑

❑

❑ External Root Resorption

❑

❑❑

❑

❑ Diseases of Periradicular Tissue of Nonendodontic Origin

❑

❑❑

❑❑ Bibliography

INTRODUCTION

Dental pulp consists of vascular connective tissue contained within the rigid dentin walls. It is the principle source of pain within the mouth and also a major site of attention in endodontics and restorative treatment.

Some important features of pulp are as follows (Fig. 3.1)

• Pulp is located deep within the tooth, so defies visualization

• It gives radiographic appearance as radiolucent line

• Pulp is a connective tissue with several factors making it unique and altering its ability to respond to irritation

• Normal pulp is a coherent soft tissue, dependent on its normal hard dentin shell for protection. Therefore once exposed, it is extremely sensitive to contact and to temperature but this pain does not last for more than 1-2 seconds after the stimulus removed.

• Pulp is totally surrounded by a hard dental tissue, dentin which limits the area for expansion and restricts the pulp’s ability to tolerate edema.

• The pulp has almost a total lack of collateral circulation, which severely limits its ability to cope with bacteria, necrotic tissue and inflammation

• The pulp consists of unique cells the odontoblasts, as well as cells that can differentiate into hard-tissue secreting cells.

These cells form dentin and/or irritation dentin in an attempt to protect pulp from injury (Fig. 3.2).

• Pulpal responses are unpredictable, “Some pulps die if you look at them cross eyes, while others would not die even if you hit them with an axe”.

• Correlation of clinical signs and symptoms with corresponding specific histological picture is often difficult.

• Thus the knowledge to pulp is essential not only for providing dental treatment, but also to know the rationale behind the treatment provided.

After all, “This little tissue has created a big issue”.

ETIOLOGY OF PULPAL DISEASES

I. Etiology of pulpal diseases can be broadly classified into:

1. Physical

• Mechanical

• Thermal

• Electrical 2. Chemical

In document Secretaría Técnica de Drogodependencias Memoria 2021 Dirección General de Salud Pública (página 53-59)