Introduction to pain control in dentistry

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Innervation of the face
The nervvous system
Nerve transmission
Definition of Pain
Pain Receptors
Pain nerve fibers
Reaction to pain
Pain Pathway
Control of Pain
Mode of action of local anesthesia

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Introduction to pain control in dentistry

  1. 1. Introduction to Oral & Maxillofacial Surgery - PainIntroduction to Oral Surgery and Pain Pathway Dr. Hesham El-Hawary Lecturer OMFS Faculty of Oral & Dental Medicine Cairo University www.elhawarydentalclinic.com ELHAWARY
  2. 2. Introduction to Oral & Maxillofacial Surgery - Pain Oral And Maxillofacial SurgeryIt is that branch of dental practice that deals with:– Diagnosis– Adjunctive and Surgical treatment of diseases– Injuries and Defectsof human jaws and associated structures ELHAWARY
  3. 3. Introduction to Oral & Maxillofacial Surgery - Pain Oral Surgery• Infection control & Aseptic surgical techniques• Anesthesia & its complications• Teeth Extraction – Simple forceps extraction – Surgical removal of teeth and roots – Impacted teeth – Complications• Oral infection• Oral tumors• Cysts of the oral cavity• Management of patients with systemic diseases• Oro-Facial pain• Maxillary sinus affections• Preprothetic surgery• Implantology ELHAWARY
  4. 4. Introduction to Oral & Maxillofacial Surgery - Pain Maxillofacial Surgery• Trauma• Temporomandibular joint disorders• Distraction osteogenesis• Management of cleft patients• Orthognathic surgery• Reconstruction ELHAWARY
  5. 5. Introduction to Oral & Maxillofacial Surgery - PainInnervation of the face ELHAWARY
  6. 6. Introduction to Oral & Maxillofacial Surgery - Pain Nervous system• The nervous system is – Network of specialized cells – Communicate information about human surroundings and himself• It processes this information and causes reactions in other parts of the body ELHAWARY
  7. 7. Introduction to Oral & Maxillofacial Surgery - Pain Nervous system Cont.• It is composed of neurons (nerve cells)• The nervous system is divided into two categories: – Peripheral nervous system – Central nervous system• Neurons generate and conduct impulses between and within the two systems ELHAWARY
  8. 8. Introduction to Oral & Maxillofacial Surgery - Pain Nervous system Cont.• The peripheral nervous system is composed of – Grouped sensory neurons – The neurons that connect them to the spinal cord and brain which make up the central nervous system• In response to stimuli: – Sensory neurons generate and propagate signals – To the central nervous system which then process and conduct back signals to the muscles and glands ELHAWARY
  9. 9. Introduction to Oral & Maxillofacial Surgery - PainNervous system Cont. ELHAWARY
  10. 10. Introduction to Oral & Maxillofacial Surgery - Pain Neuron• The structural unit of the N.S.• Two types – Sensory neuron (afferent) – Motor neuron (efferent) ELHAWARY
  11. 11. Introduction to Oral & Maxillofacial Surgery - Pain Neuron Cont. Sensory neurons (efferent)• Nerve cells that conduct impulses (as pain sensation)• From all parts of the body• To the CNS centrally ELHAWARY
  12. 12. Introduction to Oral & Maxillofacial Surgery - Pain Neuron Cont. Sensory neurons1. Dendritic zone (free nerve endings): a. Respond to stimuli b. Producing an impulse that is transmitted centrally along the axon ELHAWARY
  13. 13. Introduction to Oral & Maxillofacial Surgery - Pain Neuron Cont. Sensory neurons2. Axon a. Thin cable like structure b. Has terminal ending that form synapses with nuclei in the CNS ELHAWARY
  14. 14. Introduction to Oral & Maxillofacial Surgery - Pain Neuron Cont. Sensory neurons3. Cell body a. Located at a distance from the axon or the main pathway of impulse transmission b. Not involved in the process of impulse transmission ELHAWARY
  15. 15. Introduction to Oral & Maxillofacial Surgery - Pain Neuron Cont. Sensory neuronsCell body cont. c. The primary function of the cell body is to provide the vital metabolic support to the neuron ELHAWARY
  16. 16. Introduction to Oral & Maxillofacial Surgery - Pain Neuron Cont.Motor neuron(efferent)Conduct impulses from theCNS peripherally ELHAWARY
  17. 17. Introduction to Oral & Maxillofacial Surgery - Pain Nerve Transmission• In response to stimuli, sensory neurons generate and propagate signals (nerve impulses) to the central nervous system which then process and conduct back signals to the muscles and glands• The process by which nerve impulses are conducted along a nerve is called nerve conduction or transmission ELHAWARY
  18. 18. Introduction to Oral & Maxillofacial Surgery - Pain Nerve Transmission Cont.• The mechanism of nerve conduction is described in the following steps: 1. Resting state( Resting potential) 2. Excitation state( Depolarization) 3. Repolarization ELHAWARY
  19. 19. Introduction to Oral & Maxillofacial Surgery - PainNerve Transmission Cont. ELHAWARY
  20. 20. Introduction to Oral & Maxillofacial Surgery - Pain1. Resting state( Resting potential) Resting potential is a negative electrical potential exists across the nerve membrane i.e., the interior of the nerve is negative in relation to the exterior, (-70 to - 90 mv). ELHAWARY
  21. 21. Introduction to Oral & Maxillofacial Surgery - Pain Resting state( Resting potential) Cont.The nerve membrane in theresting state is:  Permeable to Na+ , which remains outside the nerve membrane and prevents influx of it Fairly permeable to K+ which remains inside the nerve membrane Fairly permeable to CL- which remains outside the nerve membrane ELHAWARY
  22. 22. Introduction to Oral & Maxillofacial Surgery - Pain2. Excitation state( Depolarization) Excitation of a nerve by a stimulus, which may be chemical, mechanical or thermal, leads to increased permeability of the nerve membrane to Na+ (Na+ influx) ELHAWARY
  23. 23. Introduction to Oral & Maxillofacial Surgery - Pain Excitation state( Depolarization) Cont.The rapid influx of Na+ to the interiorof the nerve causes depolarizationof the membrane from its resting stateto the firing threshold(threshold potential)i.e. Reversal of the electrical potentialacross the nerve membrane, whichmeans negatively exteriorsurface of the membrane inrelation to the interior (+40 mv) ELHAWARY
  24. 24. Introduction to Oral & Maxillofacial Surgery - Pain3. Repolarization : At the end of the depolarization, the permeability of the membrane to Na+ decreases This is followed by sodium pump which actively transport Na+ outside the cell while K+ move passively in to restoring the resting membrane potential ELHAWARY
  25. 25. Introduction to Oral & Maxillofacial Surgery - Pain Nerve Transmission Cont.The rapid sequence of depolarization andrepolarization of the nerve is called the actionpotential allowing the propagation of the impulsefrom one end of the axon to the otherWhile the impulse remains constant without losingstrength as it passes along the nerve, and this iscalled the all or non- law of nerve conduction ELHAWARY
  26. 26. Introduction to Oral & Maxillofacial Surgery - Pain Trigeminal nerve• Largest of the cranial nerves• Its name derives from the fact that it has three major branches: – Ophthalmic nerve (V1) – Maxillary nerve (V2) – Mandibular nerve (V3)• The ophthalmic and maxillary nerves are purely sensory• The mandibular nerve has both sensory and motor functions ELHAWARY
  27. 27. Introduction to Oral & Maxillofacial Surgery - Pain Painpain is unpleasant sensationcreated by noxious stimuli,usually associated with reflexwithdrawal, which is protective ELHAWARY
  28. 28. Introduction to Oral & Maxillofacial Surgery - Pain Pain receptors• Pain is received and interpreted in CNS along specific pathway called pain pathway• Pain receptors: – These are unmyelinated nerve endings – Respond to different stimuli – Provide pain sensation• Proprioceptive receptors: – These are nerve endings – Respond only to pressure• Sensation from teeth: – Pulp: pain sensation – Investing structures: proprioception ELHAWARY
  29. 29. Introduction to Oral & Maxillofacial Surgery - Pain Peripheral Nerve Fibers A- A- A-gamma A- B C alpha beta delta myelin +++ ++ ++ ++ + -Diameter( 12-20 5-12 5-12 1-4 1-3 0.5-1 µ) Velocity 70-120 30-70 30-70 12-30 14 1.2 m/sfunction motor Touch, Touch , Pain, temp., Symp Pain, pressure motor pressure temp., pressure ELHAWARY
  30. 30. Introduction to Oral & Maxillofacial Surgery - Pain Pain Nerve Fibers• These are very thin unmyelinated nerves• A-delta and C fibers, within the nerve• More easily blocked by the L.A. solutions• The thicker and myelinated fibers, such as A- alpha, beta, gamma and B fibers, transmit other sensation such as touch and pressure with the motor fibers ELHAWARY
  31. 31. Introduction to Oral & Maxillofacial Surgery - Pain Reaction to pain (Pain Threshold)• Pain threshold is the minimum stimulus which elicits pain• Differ between individuals• Vary in the same individual on different occasions• Affected by fear, apprehension, age, sex, physical fitness, race and fatigue ELHAWARY
  32. 32. Introduction to Oral & Maxillofacial Surgery - Pain Pain Pathway ELHAWARY
  33. 33. Introduction to Oral & Maxillofacial Surgery - Pain First Order Neuron• Stimuli from the oral cavity• received by nerve fibers• Conducted as impulses along the three branches of the 5th cranial nerve• Into the gasserian (semilunar) ganglion (GG) ELHAWARY
  34. 34. Introduction to Oral & Maxillofacial Surgery - Pain First Order Neuron Cont.• The nerve cells in GG are unipolar nerve cells• Each has an axon which bifurcate into a Y or T shaped division ELHAWARY
  35. 35. Introduction to Oral & Maxillofacial Surgery - Pain First Order Neuron Cont.• The central branches of the T shaped fibers make up the sensory root of the trigeminal nerve• the peripheral branches of the T shaped fibers form the three branches of the 5th cranial nerve ELHAWARY
  36. 36. Introduction to Oral & Maxillofacial Surgery - Pain First Order Neuron Cont.• Then from the GG the impulses are passed by the central branches of the unipolar cells into the pons ELHAWARY
  37. 37. Introduction to Oral & Maxillofacial Surgery - Pain First Order Neuron Cont.• Some branches end in a collection of nerve cells in the pons called the P.S.N., responsible for touch• other branches descends through the medulla where it terminates in the A.S.N. responsible for pain & temp ELHAWARY
  38. 38. Introduction to Oral & Maxillofacial Surgery - Pain Second Order Neuron Cont.• Originates From A.S.N. and P.S.N another nerve fibers• Crosses the midline and ascends in a spinothalamic tract of the 5th cranial nerve• Terminates in P.V.N. in the thalamus ELHAWARY
  39. 39. Introduction to Oral & Maxillofacial Surgery - Pain Third Order Neuron Cont.• Originates from P.V.N. in the thalamus• Carries the pain impulse to the post- central convolution of the cortex where all sensations are felt ELHAWARY
  40. 40. Introduction to Oral & Maxillofacial Surgery - Pain Control of pain• Removing the cause• Raising the pain threshold• Blocking the pathway of the painful impulses• Preventing the pain reaction by cortical depression ELHAWARY
  41. 41. Introduction to Oral & Maxillofacial Surgery - Pain Control of pain• Removing the cause• Raising the pain threshold• Blocking the pathway of the painful impulses• Preventing the pain reaction by cortical depression ELHAWARY
  42. 42. Introduction to Oral & Maxillofacial Surgery - Pain Anesthesia• Anesthesia: the condition of having sensation blocked (including the feeling of pain)• Analgesia: blocking the conscious sensation of pain• Hypnosis: produces unconsciousness without analgesia ELHAWARY
  43. 43. Introduction to Oral & Maxillofacial Surgery - Pain Types of anesthesia• Local Anesthesia: Any technique that render part of the body insensitive to pain without affecting consciousness• General anesthesia: Drug-induced loss of consciousness during which patients are not arousable, even by painful stimulation ELHAWARY
  44. 44. Introduction to Oral & Maxillofacial Surgery - Pain Mode of Action of Local Anesthesia• Displacing calcium ions from receptors site• The mechanical or reversible coagulation theory• The physiological theory – interference with the nerve tissue metabolism• Acetyl Choline and enzyme system theory• Electrical potential theory ELHAWARY
  45. 45. Introduction to Oral & Maxillofacial Surgery - PainThank Youwww.elhawarydentalclinic.com ELHAWARY

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