Pulp and Periradicular Tissue Biology and Endodontics PDF

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Pulp and Periradicular Tissue Biology and Endodontics Nature of the Pulp I. II. III. IV.

Metabolic Activity Connective Tissue Fiber Microcirculatory System Repair I. Metabolic Activity Measure the rate of O2 consumption and production of CO2 or lactic acid by pulp tissue - The greatest metabolic activity is found in the region of the odontoblastic layer and lowest in the central pulp, where most of the nerves and BV found - Dental materials such as eugenol, ZOE, CaOH and silver amalgam have shown to inhibit O2 consumption by pulp tissue - These agents may be capable of depressing the metabolic activity of pulpal cells Connective Tissue Fiber -

II.

 Fibers:

Fibers embedded in ground substance or ECM Ground substance is responsible primarily for the viscoelasticity and filtration of CT tissue Amorphous/gel form Has H2o holding property

1. Collagen- gives strength of tissue Tropocollagen- is a single collagen molecule 2. Elastin- provides elasticity to tissue and BV but not part of ECM Collagen • Type I collagen- found in skin, tendon, bone, dentin and pulp • Type II collagen- found in cartilage • Type III collagen- found in most unmineralized CT tissues, found in dental papilla • Type IV and VII- components of basement membrane • Type V- constituent of interstitial tissue • Type VI- distributed in low concentrations in soft tissues at interfibrillar filaments III.

Microcirculatory System -

Presence of network of vessels within the odontoblastic layer

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-Nerve bundles pass upward through radicular pulp with BV and reach coronal pulp and ramify into the Plexus of Raschkow-

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Pulp is innervated by myelinated and unmyelinated nerve fibers

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 Includes : Afferent neurons – conducts sensory impulses

Autonomic fibers- provide neurogenic modulation of the microcirculation and regulate dentinogenesis IV.

Repair

a. Cleaning ability of Macrophages b. Proliferation of fibroblasts c. Formation of collagen **Adequate blood supply to transport inflammatory elements into the area of injury **And provide young fibroblasts to produce collagen **Increase healing potential of young teeth Functions of the Pulp ( FINDS) 1. Inductive - Function of the odontoblasts dentinogenesis 2. Formative a. Synthesizing and secreting organic matrix; b. Transporting inorganic components to newly formed matrix c. Creating an environment that permits mineralization of matrix 3. Nutritive  Blood vessels- food  Dentinal tubules-

hydration

4. Defensive a. Formation of reparative dentin or secondary dentin b. Inflammatory reaction 5. Sensory - The sensory system of the pulp appears to be well suited for signaling potential damage to the tooth. Inner acted by a large number of myelinated and us myelinated nerve fibers a. A- delta fibers myelinated -

Fast, sharp and severe sensation Associated with dentin hypersensitivity

b. C-fibers unmyelinated -

slower, duller and more diffuse Associated with pulp inflammation

**The sensory nerves of the pulp arise from the trigeminal nerve. Then pass thru the radicular pulp by way of the foramen in close association with arterioles and venules. Embryology of the Pulp • Pulp is derived from cephalic neural crest • Neural crest cells arise from the ECTODERM along the lateral margins of the neural plate and migrate extensively Dental Papilla • Give rise to the mature dental pulp • Develops as ectomesenchymal cells proliferate and condense adjacent to the dental lamina at the sites where teeth will develop 6 weeks i.u. • Tooth formation begins as a localized proliferation of ectoderm associated with the Maxillary and Mandibular processes • Proliferative activity results in the formation of 2 horseshoe shaped structures, one on each process; the primary dental lamina • Each primary dental lamina splits into a vestibular and dental lamina Stages of Development 1. Bud stage 2. Cap stage 3. Bell stage Zones of the Pulp ( OCCP) 1. Odontoblastic zone 2. Cell free zone/Zone of Weil 3. Cell rich zone 4. Pulp core/Pulp proper 1. Odontoblastic zone -

Formative cells of dentin Found subjacent to the A layer 3-5 cells in More cells in coronal portion than radicular portion Between odontoblasts are cell-cell junctions

predentin thickness

2. Cell free zone/ Zone of Weil-

Subjacent to the odontoblastic layer Free of cells Presence or absence of this zone depends on the functional status of the pulp

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Traversed by blood capillaries,unmyelinated nerve fibers and cytoplasmic processes

3. Cell Rich Zone - Source of cells that differentiate into 2˚ or replacement odontoblasts upon injury - A stratum or layer containing a high proportion of fibroblasts compared to the pulp core - May include macrophages,dendritic cells, and undifferentiated mesenchymal cells - Mitotic activity is rare in normal pulps 4. Pulp Core/Pulp Proper - Central mass of pulp - Contain larger BV and nerves - CT cells consists of fibroblasts or pulpal cells Cells of the pulp 1. Odontoblasts - Responsible for dentinogenesis - Most characteristic cell of the dentin-pulp complex presence within the tubules makes dentin a living tissue - Synthesis of collagen type I 2. Pulp Fibroblast - Most numerous cell in the pulp - Synthesize Type I and III collagen as well as proteoglycans, fibronectin and GAGs - Produce and maintain proteins of the ECM - More abundant in cell rich zone - Proteoglcans- characteristic gel that provide protection against compression of CT - Fibronectin- act as mediator for cell-cell and cell-matrix adhesion (Proliferation, Organization of Cells) 3. Undifferentiated Mesenchymal Cells - Reserve cells - First cells to divide into fibroblasts or odontoblasts 4. Cells of Immune System Macrophages, T- lymphocytes, Mast cells, Dendritic cells - These cells are recruited from the blood stream - Antigen presenting cells - Macrophages- active in phagocytosis, close proximity to BV - T- Lympho- help in initiation of immune response - Mast cell- found in chronic inflammation, contain chemical factors important in inflammation - Dendritic cells- accessory cells, play a role in the induction of T-cell dependent immunity

Blood supply - Dental branches of superior and inferior alveolar arteries and veins Innervation • Maxillary and Mandibular branches of the trigeminal nerve • Superior cervical ganglion Dentin • Composition 70% Inorganic material hydroxyapatite is the principal inorganic material Ca10 (PO4)6(OH)2 - 10% Water - 20% Organic matrix (91% is collagen) Noncollagenous matrixphosphoproteins, Proteoglycans, g-carboxyglutamate- containing protein(Gla protein), acidic glycoprotein,growth factors, lipids  -

What is Dentin? Hard biologic tissue that makes up the bulk of the tooth Covered coronally by enamel and apically by cementum Encloses and protects the pulp Elasticity of dentin provides flexibility for the overlying brittle enamel

Types of Dentin • Primary/ Developmental dentin - formed during odontogenesis and apexogenesis • Secondary dentin - formed continuously as a response to mastication causing pulp recession • Tertiary dentin/Orthodentin/Osteodentin - irritation dentin, formed as a response to caries,attrition,abrasion,erosion and cavity preparation

Predentin -

Unmineralized organic matrix of dentin between the odotoblastic layer and mineralized dentin It is produced by odontoblasts Thought to bind to Ca and play a role in mineralization

PERITUBULAR DENTIN - Dentin lining the tubules - Low collagen content makes it more susceptible to acid than ITD INTERTUBULAR DENTIN - Dentin in between tubules - Bulk of dentin - Provide tensile strength to dentin DENTINAL TUBULE - Contain cell processes of odontoblasts

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Slightly tapered with the widest portion toward the pulp

Dentinal Fluid - Occupies 1% of superficial dentin but about 22% of total volume of deep dentin - Exposure of the tubules by tooth fractures or cavity preps result in outward movement of fluid to the exposed dentin surface - Bacteria can be introduced to DF as a result of caries, resto procedures,growth of bacteria beneath restorations - DF may serve as vehicle for egress of bacteria from necrotic pulp into periradicular tissue Hydrodynamic Mechanism Dentin Hypersensitivity - Fluid movement in the dentinal tubule is translated into electrical signals by sensory receptors located within the tubules or subjacent odontoblast layer - Researchers found that outward flow of fluid produced a much stronger nerve response than inward movement - Pain producing stimuli include heat,cold, air blasts, probing - Hydrodynamic stimuli or fluid movement- activates A-fibers - Prolonged exposure causing heat- activates C- fibers (particularly by heat) - Pain producing stimuli are more readily transmitted from dentin surface when tubules are open by acid,airblast,probing Cementum - 45%- 50%  inorganic material - 50%- 55%  organic material - Cementum are worn away by brushing, flossing or toothpick use - Desensitization occur as a result of gradual occlusion of the tubules by mineral deposits and reparative dentin on the pulpal end of the tubule Types of Cementum a. Acellular afibrillar cementum b. Acellular extrinsic fibril cementum - sharpey’s fibers c. Cellular mixed fibril cementum -cementocytes,intrinsic and extrinsic fiber d. Cellular intrinsic fibril cementum - type of cementum formed during repair e. Cementoid- uncalcified part of cementum Periodontal Ligament - Cell rich fiber - Rich CT between the root surface and alveolar bone Function of PDL a. Supportive - cushion effect b. Sensory - proprioception c. Homeostatic

- continuous remodeling d. Nutritive - Presence of blood supply

Cells of PDL 1. Fibroblasts - principal cell of the PDL 2. Cementoprogenitor and Osteoprogenitor cells - resembles inactive fibroblasts 3. Macrophage - important for cell defense 4. Leukocyte - appears when needed during states of disease Periodontal Fiber 1. Collagen 2. Oxytalan Alveolar bone - 67% Inorganic - 30% Organic  Function: - Skeletal support - Mineral storage for hemopoiesis Types of Alveolar Bone Cells a. Osteoblast - forms bone b. Osteocyte - matrix forming cell c. Osteoclast- resorbs bone Types of Bone Formation A. Endochondral - from collagen to bone B. Intramembranous - direct formation of bone C. Sutural Bone Growth -formation from sutures Lamina -

Dura Radiographic AB First line of bone Surrounding the tooth where PL is attached

Age changes a. Formation of 2˚ dentin= reduces pulp chamber size and root canals b. CDJ remains the same c. ↓ cellularity ↑ collagen fibers particularly in the radicular area d. Odontoblasts decrease in size and number and may disappear altogether in some areas of the pulp e. Reduction in the number of nerves and blood vessels f. In dentin, ↑peritubular dentin Dentinal sclerosis which ↓dentinal permeablity ↑number of dead tracts

EXAMINATION AND TESTING EXTRAORAL EXAMINATION 1. Gait and Balance 2. Facial features symmetry (swelling, nasolabial fold) eyes ( pupillary dilation or constriction) alertness 3. Skin lesions, lacerations, scars, contusions, discolorations 4. Mandibular range of motion limitation in opening and closing 5. Head and Neck exam Bimanual Palpation a. Cervical/submandibular lymph nodes (size, mobility, tenderness) b. Masticatory Muscles (hypertrophy, atrophy, tenderness) c. TMJ (opening and closing) ** Sinus Tracts Openings in the skin that may be odontogenic in origin INTRAORAL EXAMINATION 1. Soft Tissue Examination - gingiva, mucosa, tongue, and cheek raised lesions or ulcerations must be documented and when necessary, evaluated by biopsy. 2. Intraoral Swelling - must be visualized and palpated to determine if diffused or localized/ firm or fluctuant, may be present in attached gingiva, alveolar mucosa, mucobuccal fold, and palate or sublingual. 3. Intraoral Sinus Tracts - by endodontic infection pathway extends directly from the source of infection pathway is not entirely lined with epithelium ** On the other hand, FISTULA is abnormal communication between 2 internal organs or a pathway between 2 epithelium lined surfaces  To trace the sinus tract: A size #25 GP cone is threaded into the opening of the sinus tract until resistance is felt - Take a radiograph - Termination is the source of infection PERIODONTAL EXAMINATION 1. Percussion - The test shows if the PDL is inflamed or periapical involvement - Does not indicate if the pulp is vital or nonvital - The inflammation may be secondary to physical trauma, occlusal prematurities, periodontal disease or pulpal disease extension - Use a control tooth and adjacent teeth that are certain to respond normally Gloved finger Blunt end of a mouth mirror + mild pain ++ moderate pain +++ severe pain 2. Palpation - Test shows if the periodontal inflammation has reached the periosteum - May reveal soft tissue swelling or bony expansion

+ mild pain ++ moderate pain +++ severe pain 3. Mobility - Compromise in the periodontal support - Will not indicate pulp vitality May be a result of acute or chronic physical trauma, parafunctional habits, perio disease, root fractures, rapid ortho mov’t, pulpal disease extension - Mobility reverses after the initiating factors are repaired - Finger pressure Back ends of 2 mirror handles - + 1 mobility: the first distinguishable sign of movement greater than normal - + 2 mobility: horizontal tooth movement no greater than 1mm - + 3 mobility: horizontal tooth movement greater than 1mm, with or without the visualization of rotation or vertical depressibility ** Any mobility over +1 should be considered abnormal but teeth must be examined relative to the adjacent or contralateral teeth 4. Pocket Probing - Clinician must probe and record all surfaces of the tooth - Indication of the depth of the gingival sulcus - Test show “ attachment loss” - Deep pocket depths indicate pathologic horizontal or vertical bone loss Essential in distinguishing between disease of periodontal origin from disease of pulpal origin PULP TESTS 1. THERMAL TEST - Normal response to hot and cold- the sensation is felt but disappears immediately after removal of thermal stimulus - Abnormal response: a. Lack of response to stimulus b. The lingering or intensification of a painful sensation after stimulus has been removed c. Immediate excruciating painful sensation as soon as stimulus is placed upon the tooth 1. Heat test - Sticks of GP 3 inch stick of GP; Tooth should be covered with a lubricant (petroleum) 2. Cold Test - Must be used in conjunction with EPT Isolation with rubber dam a. Ice sticks applied in the middle 3rd of the tooth facial/ buccal until Px feels pain or sensitivity. b. Compressed gasses ethyl chloride sprays- least effective 2. ELECTRIC - Vitality is determed by the intactness and health of pulp’s vascular supply, not the status of the pulpal nerve fibers

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A response by the pulp to the electric current only say that some nerves are still capable of responding Stimulate the alpha sensory fibers within the pulp Used as adjuncts to thermal testing There must be a CONTROL TOOTH ( same tooth type and arch location) The suspected tooth must be tested 2x for confirmation Probe placed in the incisal 3rd A tingling or warming sensation is felt by the tooth being tested

RADIOGRAPHIC EXAMINATION  Intraoral Radiograph - A 2D image of a 3D structure - May be useful in determining the existence of additional roots, location of pathosis and anatomical structures - Change in vertical and horizontal angulation What to look for in radiographs 1. Anatomic landmarks 2. Caries and Restorations 3. Calcifications 4. Presence of extra roots/ canals 5. Immature apices 6. Tooth/root fractures 7. Periapical lesions

ROOT FRACTURES AND CRACKS  CRACKS IN TEETH 1. Craze Line -Cracks in enamel that do not extend into dentin - Occur naturally or develop secondary to trauma - Usually in posterior teeth -No symptoms No necessary treatment 2. Fractures (also referred to as cracks) -Deeper into dentin -Extending mesial to distal involving marginal ridge -Symptoms range from none to severe pain -May progress to “split tooth” -Depending upon the extent, may be treated by simple restoration, endodontics or even extraction 3. Split Roots - Occur when fracture extends from one surface of the tooth to another surface of the tooth -Tooth separating into segments If the split is oblique, it is possible the smaller separated segment be restored ( fractured cusp)

-Split extending below the osseous level or involves the pulp, tooth may not be restorable and endodontic treatment may have an unfavorable prognosis Vertical Root Fracture - A severe crack in the tooth that extends longitudinally down the long axis of the root Involves the pulp and periodontium - May be present prior to RCT, secondary to RCT or after completion of RCT - Difficult to diagnose and may go undetected - Most common cause may be iatrogenic dental treatment ( posts) - Tooth may be painful from mild to severe, especially when px occludes or release in a specific direction and no healing of a RCT tooth - Most commonly found Md 2nd molars -Mx 1st molars -Mx premolars

Role of Root canal therapy -

Reduce the number of microorganisms to a non- critical level of infection or total elimination of infection that will later on promote healing

Pulpal Diseases 1. Normal Pulp 2. Pulpitis a. Reversible b. Irreversible i. Symptomatic ii. Asymptomatic 3. Necrosis I. Normal Pulp No spontaneous pain Thermal: mild to moderate, response is transient EPT: mild to moderate, response is transient Percussion: (-) Palpation (-) Mobility: (-) Rx: clearly delineated root canal, no resorption, no caries, no pulp exposure, intact lamina dura Tx: none

Pulpitis a. Reversible Pulpitis -Tooth is irritated upon stimulation but reverts back once stimulus is removed -Causative factors: caries, exposed dentin, recent dental tx, defective restoration -"Reactive" a response produced only when stimulated Thermal: momentary, quick, sharp, hypersensitive EPT: mild to moderate transient response Percussion: (-) Palpation: (-)

Mobility: (-) Rx: presence of caries but not encroaching pulp defective restoration, no resorption, intact lamina dura Tx: restore defective filling, removal of caries b. Irreversible Pulpitis (Symptomatic or acute) - Intermittent, spontaneous pain -Prolonged pain even upon removal of stimulus (especially cold) -Pain may be sharp, localized or referred -Pain may be relieved by application of heat or cold -Affected by postural changes -If left untreated it may lead to necrosis Thermal (+) moderate-strong painful response that lingers for several seconds or longer after stimulus has been removed EPT: (+) little diagnostic value Percussion: (-) Palpation: (-) Mobility: (-) Rx: may have thickening of PDL space, intact lamina dura, deep restorations, deep caries, pulp exposure Tx: RCT or EXO C.Irreversible Pulpitis ( Asymptomatic or chronic) - No pain sometimes may complain of dull ache -Wide open carious lesion -Had passed an inactive acute phase -Hyperplastic pulpitis (pulp polyp) occurs in children and young adults -Pinkish red globule of tissue protruding from the pulp chamber and is insensitive to manipulation -Internal resorption may be stimulated by trauma appears as a pink spot if resorption is in the crown Thermal: (+) or (-) EPT: (+) or (-) increased threshold Percussion: (-) Palpation: (-) Mobility: (-) Rx: deep caries well into the pulp, may have thickening of periodontal space, intact laminate dura Tx: RCT or EXO

Necrosis - When necrosis occurs the pulpal blood supply is non- existent, pulpal nerves are non-functional - Bacterial growth may be sustained within the canal - Subsequent to irreversible pulpitis - Partial necrosis may produce symptoms associated to irreversible pulpitis - With or without crown discoloration

Thermal:...