origin of pulpal pain endodontic pptx

origin of pulpal pain2

1. Pain of Pulpal Origin

2. Outline Introduction Pathways of pain Innervation of pulp & dentine Types of sensory nerve fibers of the pulp Theories of pulpal pain Changes in nerve function in inflammation, neurogenic inflammation and inflammatory mediators Types of pulpal pain Dentine hypersensitivity The role of pulpal inflammation in dentine sensitivity Diagnosis of pulpal pain

3. Introduction Definition of Pulpal Pain Pulpal pain is pain originating from the dental pulp , which is the innermost part of the tooth containing nerves and blood vessels .

4. Anatomy of the Dental Pulp The dental pulp is a soft tissue that is located in the center of the tooth. is a vital structure that contains nerves and blood vessels, Which is provides sensory innervation ,nutrition, and defense of the tooth.

5. Pathways of pain Pain in dental pulp occur when noxious stimulus activate pain receptors “ noviceptors ” in the pulp Signals are transmitted via nerve fibers through the root canal to the trigeminal nerve & then to the brain The brain interprets these signals as pain Pathway of pain also known as nociceptive pathway include four major steps: Transduction Transmission Modulation Perception

6. Pathways of pain 1-Transduction Noxious stimuli ( cold , heat,pressure,chemicals ) activate pain receptors “ nociceptors “ located in tissue 2-Transmission The nociceptors generate electrical impulses that travels along nerve fibers via peripheral nerves to the central nerves system (CNS) 3-Perception The brain interprets the signal as pain 4-Modulation The brain can alter the perception of pain through descending pathways

7. Innervation of pulp & dentine The dental pulp is richly innervated mainly by axons from the trigeminal nerve , predominantly sensory in nature and mainly committed to pain perception. A smaller population of pulpal nerves are autonomic sympathetic fibers emanating from the superior cervical ganglion and associated with pulpal vasoconstriction. Each tooth is innervated by about a thousand trigeminal axons 9,11 , which may have branched before entering the apical foramen and may innervate more than one tooth. In the radicular pulp, the nerve fibers are bundled together, but once they reach the coronal pulp 8, 12, 13 they divide into smaller bundles.

8. Innervation of pulp & dentine The axons then branch extensively and each may form 50 - 100 terminals in the peripheral pulp, forming a network under the odontoblastic layer, known as the plexus of Raschkow . The density of nerve endings is especially high in the pulp horns, where as many as 50% of the dentinal tubules are innervated Many of the tubules contain multiple nerve terminals. 8

9. Innervation of pulp & dentine Schematic presentation of the intradental innervation. The nerve bundles enter the pulp via the apical foramen/foramina and branch extensively especially in the coronal pulp. The pulp-dentin border zone in the peripheral pulp (pulp tips) is the most densely innervated area, where the nerve endings also extend the longest distance (100 - 150 um) into the dentinal tubules.

10. T ypes of pulpal sensory nerve fibers There are both myelinated ( 20 - 25%) and unmyelinated ( 75 - 80%) afferent nerve fibers in the pulp . 8, 12, 13 These two fiber groups differ greatly in their functional properties. 6, 7, 14, 15

11. T ypes of pulpal sensory nerve fibers C-fibers activation results in dull pain or ache in pulpal inflammation A-fibers activation in healthy pulp results in sharp and usually short-lasting pain , not outlasting the stimulus 7% 93%

12. Heat Touch Pressure Chemicals Cold Pulp perception to these stimuli is pain as it lacks proprioceptors

13. Theories of pulpal pain Three main theories have been proposed to explain dentin sensitivity & pulpal pain: Direct neural stimulation theory Fluid or hydrodynamic theory Transduction theory

14. Theories of pulpal pain Direct neural stimulation theory: This theory states that the nerve endings inside the dentinal tubules are directly stimulated and cause sensitivity/pain. The arguments against this theory are as follows: 1-Even though nerve endings are seen inside the dentinal tubule, they are confined to the inner dentin and are absent in the outer dentin. 2-Topical application of the local anaesthetic to the surface of dentin does not eliminate dentin sensitivity.

15. Theories of pulpal pain Transduction Theory: This theory states that various stimuli stimulate the odontoblastic process as a receptor which conducts the impulses to the nerve endings located in the inner dentin. The arguments against this theory are as follows: 1-Neurotransmitter vesicles are absent in the odontoblastic process. 2-There is no synaptic relationship between the odontoblastic process and the nerve endings

16. Theories of pulpal pain Fluid Or Hydrodynamic Theory This theory states that dentin sensitivity is due to the movement of fluid inside the dentinal tubules. Various stimuli such as heat, osmotic pressure and drying can cause outward movement of fluid, whereas cold stimulus causes inward movement of fluid. Movement in either direction causes mechanical disturbance of the nerve endings which are present in the inner dentin and are close to the odontoblasts and their process. The free nerve endings in the plexus of Raschkow sense these disturbances, resulting in sensitivity/pain. This widely accepted theory proposes that nerve endings act as mechanoreceptors.