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PAIN CONTROL IN OPERATIVE DENTISTRY A quickened pulse rate, a hastened heart beat, clammy, sweaty skin, thirsty dry mouth, a tightness in the gut and a feeling in the mind Do we really have to do this. Hold on, control your imagination, all I’m describing is an attack of dental anxiety, phobia and pain. Good morning and welcome to today’s seminar on pain control in operative dentistry.

Lets confabulate on this under the following topics: • Introduction • Definition and etiology of pain • Methods of pain control • Latest advances • Conclusion

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INTRODUCTION Since ancient times, the profession of dentistry has been associated with excruciating trauma and unbearable discomfort. Vivid imagery and exaggerated cartoonery depicted dentists as the epitome of satanic devils ready to inflict merciless agony. So much so, that pain become synonymous with dentistry and dentistry with pain. However, the era of modern dentistry decided to shun this image and made rapid strides in changing the perception of dentistry from a heartless monster to a caring angel. Various advances in anesthetics, operating techniques and clinical ambience and approach have shown the way towards truly painless dentistry. Definition – What is painďƒ  Pain is defined as an unpleasant sensory and emotional experience resulting from a stimulus causing, or likely to cause, tissue damage or expressed in terms of that damage. This is affected by emotional factors. Various assessments are used to evaluate pain like the linear and visual analog scale, Minnesotta Multiphasic Personality Index (MMPS) and other subjective and objective criteria. Now, let’s have a look at the various possible causative factors for pain in operative dentistry.

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1) Firstly the patient  Pain being a highly subjective and individualistic response, the patient plays a major role in how much pain is felt. Stoic, controlled patients may bear even the most unpleasant procedures quietly while highly hysteric patients might jump even if you don’t touch them. Hence, patient conditioning is such an integral and vital part of pain management. 2) Second are the instruments, materials and armamentarium used in dentistry – rotary instrumentation, caustic chemicals, improperly handled hand instruments and ironically the anesthetic needle itself are associated with pain responses. Heat and pressure play an important role in these mechanisms. 3) The Pulp- Dentin Organ – Enamel is sensationless. Any procedure performed purely on enamel is incapable of causing pain. However, procedures that involve the dentin and pulp elicit only pain as a response; if any. The various theories of pain transmission of pain in dentin and pulp are still exploring the exact cause but sensitivity is an integral part of the dentinal response. 4) Improper handling of tissues – Careless and insensitive handling of the oral tissues may result in operative or post operative discomfort and pain. Hence, delicate management of oral tissues is a must.

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Now we come to the methods or techniques of pain control: These can be broadly described under – 1) Gaining the confidence of the patient. 2) Ideal instrumentation and proper implementation. 3) Use of cooling devices. 4) Use of palliative drugs and obtundants. 5) Dessication of dentin. 6) Pressure anesthesia with cocaine. 7) Local anesthesia. 8) Use of inhalation sedation or nitrous oxide sedation 9) Hypnosis and psychotherapy. 10)General anesthetics. 1) Gaining the confidence of the patient: The first axiom is “Treat the individual, not just the tooth.” A patient is an individual just like us with his / her own complexes, beliefs and fears. The correct psychological approach will help us not only to understand their needs but also alleviate any apprehension skillfully. Individual personality of the dentist and the right demeanour can have a profound influence on patient confidence and reduction of

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anxiety with subsequently reduced perception of pain. The art and science of skillful conversation should be mastered to create a warm and lasting relationship. Succinct yet thorough explanation of the involved procedures with required modalities to accommodate age related understanding goes a long way in achieving patient cooperation. Also important is the look and feel of the workplace. The ambience of the operatory, the care manifested in minor detailing and the entire interior the sights, smells and sounds should convey a warm, caring message to soothe the patient. Every procedure and action should be performed confidently to give the impression of efficiency and instill a sense of security in the patient. All these measures can indeed make the experience highly rewarding for the individual and the clinician. 2) Correct instrumentation: Instrumentation can be either – Hand cutting Rotary instrumentation – Slow speed or High speed. Hand cutting instruments:

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The main principle of cutting with hand instruments is to concentrate force in a very thin cross section of the instrument at the cutting edge. Therefore, the thinner the cross section, the more sharper the instrument and hence the more efficient it is. Dull or blunt instruments require more pressure to cut the tooth structure which also causes more frictional heat thus eliciting pain. It has been shown that when a force of 10 lbs is applied on a sharp edged instrument, the cutting efficiency is equal to 200lbs whereas in a dull edged instrument it falls down to 20lbs. Thus sharpening stones should be used to always maintain sharp instruments resulting in efficient work and lesser trauma. Rotary instruments: Rotary instrumentation can govern the presence or absence of pain through – 1) Speed 2) Pressure 3) Heat production and 4) Vibration all of which are inter related. a) Low speed instruments such as micromotor and other devices results in ďƒ  (Ultra low – 300-3000rpm, low 3000-6000 rpm, medium 20,000-45,000, high 45,000-1,00,000, ultrahigh 1,00,000 and more). 1. Application of more pressure on the cutting surface. 6


2. Increase in the vibration which is 2 fold in origin i.e.,

amplitude

and

undesirable

modulating

frequency. At low speed, amplitude is increased and frequency is decreased. 3. Because of the friction, there is more heat production which is also directly proportional to pressure, revolutions per minute and area of tooth in contact because if any of these factors are increased, heat production increases which can cause damage to the pulp if temperatures reach 130째F though even 110-113째F can produce inflammatory responses. To overcome the disadvantages of low speed, high and ultrahigh speed instrumentation was introduced into dentistry. These rotate at speeds above 45,000 to 1,50,000 rpm and more and their advantages include: 1) Efficient rapid cutting. 2) Convenient to operator and patient. 3) Minimal vibration. 4) Low frictional heat with coolants. 5) Longevity of cutting instruments.

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6) Less pressure and sensitivity ďƒ  low speed (25lb), high speed (1lb), ultrahigh (1-4 ounces). Disadvantages: 1. Overcutting. 2. Visibility is hampered. 3. Lesser tactile sensation. A major advancement with high speed cutting was the introduction of coolants to lower the frictional heat and enhance efficiency and comfort. 3) Use of cooling devices: Coolants minimize pain and maximize efficiency with high speed. The commonly used coolants are: a) Air. b) Water. c) Combination of both which is the most popular and highly effective. Also, the use of chilled burs is said to diminish pain. CO2 and ethyl chloride have also been experimented with. 4) Use of Obtundants: Here, soothing and palliative type of cements or medicaments are used on dentin. Desensitizing agents like ZnCl2, Ag(NO3)2, Ferric oxalates can minimize dentinal sensitivity. 8


Commonly used obtundant is ZOE which can be placed over cut dentin as an intermediate dressing in patients having severe sensitivity. Also in cases like cracked tooth syndrome a band is cemented around the tooth with ZOE where it acts as an obtundant as well as a cementing medium. 5) Dessication of dentin: Previously, a school of thought advocated that dessication or drying of dentin by a blast of warm air gives relief from sensitivity and subsequent pain. However, recent school of thought states that over dessication should be avoided so as to prevent the fluid movement inside the dentinal tubules, which causes pain, as hypothetized by the hydrodynamic theory. Even during cavity cleansing, a 3-way syringe should be used taking advantage of both air and water. 6) Pressure anesthesia with cocaine: This method is particularly effective in anesthetizing the pulp of deciduous and young permanent teeth but not effective in areas of secondary dentin and carious areas. It is quite effective for a short duration procedure.

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The solution used has the following ingredients as elucidated by Stanley W. Clark. a) Cocaine – 25% b) Ether – 10% c) Chlorophenol – 15% d) Alcohol – 50%. Technique: Access should be gained to the dentin cutting through enamel with a 1mm inverted cone bur. The opening is enlarged, changing it to the form of a section of a cone with the larger end at the surface. A very small bit of cotton pledget (1mm) should be moistened with the solution and placed at the bottom of the opening. A slightly larger piece of unvulcanized rubber should then be placed over the cotton and pressure, at first light and gradually increased to heavy is applied in a series of thrusts using a round, flat faced condenser about 1 to 2mm in diameter. This forces the solution through the dentinal tubules to anesthetize the pulp. This must be done in a dry field. 10


7) Local Anesthesia: It is the most widely used and popular technique of effective pain control. It is defined as a transient regional loss of sensation to a painful or potentially painful stimulus resulting from a reversible interruption of peripheral conduction along a specific neural pathway to its central integration and perception in the brain. Cavity preparation and Endodontic procedures may be painlessly carried out after securing anesthesia by infiltrating the apical tissues or by nerve blocking with one of the LA solutions. It reduces pain as well as permits the dentists to work faster and save time. One should operate just as carefully when preparing cavities in teeth with anesthetized pulps as though they are not anesthetized. Local anesthesia administration should be monitored by performing a preanesthetic evaluation. Any history of allergies, cardiac anomalies, anemia or other blood dyscrasias, kidney, liver or thyroid problems, infectious diseases, epilepsy, bleeding disorders, diabetic complications or psychiatric disturbances should be noted and adequate provisions or preparations made for their handling. The various local anesthetics used are basically of ester and amine type. Though choice mainly depends on situation and dentist, lignocaine with 11


a vasoconstrictor, specifically adrenaline is the most popular anesthetic of choice. The vasoconstrictor aids in prolonging the action of the anesthetic. The average duration of pulpal anesthesia obtained with vasoconstrictor is approximately 1 hour while it is just 5-10 minutes without vasoconstrictor. Another important consideration is preparedness for any medical emergencies.

Anesthetic

toxicity,

allergic

reactions,

syncope,

hyperventilation etc are all contingencies for which an average practitioner should be equipped and emergency drugs should be available at hand. Proper preparation and precautions will make local anesthesia a safe and predictable pain control procedure. LA techniques: 1. Local

infiltration

(supraperiosteal

infiltration)

–

Supraperiosteal anesthesia is described as a technique in which anesthetic is deposited into the area of treatment (0.60.9ml). Small terminal nerve fibres in the area are blocked and thus rendered incapable of transmitting impulses. This is commonly employed in maxillary teeth because of the ability of anesthetic solutions to diffuse through periosteum and relatively thin cancellous bone.

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2. Regional nerve block: Nerve block is defined as a method of achieving regional anesthesia by depositing a suitable local anesthetic solution close to a main nerve trunk, preventing afferent impulses from traveling centrally beyond that point. i)

Maxillary anesthesia – Maxillary nerves that can be anesthetized include the PSA, the anterior superior

alveolar,

greater

palatine,

the

nasopalatine and the second division of the trigeminal. PSA block, also called as the zygomatic or tuberosity block, is indicated when pulpal anesthesia is required for the maxillary third, second and first molars (except mesiobuccal root of 1st molar) with the underlying buccal alveolar process, periosteum, connective tissue and mucous membrane also being anesthetized. Infraorbital nerve block produces anesthesia of anterior superior alveolar and middle superior alveolar providing anesthesia for central and lateral incisors, canines and premolar.

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Greater (anterior) palatine nerve block provides anesthesia to both the hard and soft tissues ranging from the 3rd molar as far anterior to as the first premolar. In the region of first premolar, partial anesthesia may be encountered as branches of the nasopalatine nerve overlap. Nasopalatine nerves enter the palate through the incisive foramina, located in the midline just palatal to the central incisors and directly beneath the incisive papilla, which anesthetize the premaxilla as far distal as the first premolar. Palatal anesthesias are often traumatic because of the density of the palatal soft tissues and their firm attachment to bone. So, it is advisable to use topical anesthesia before palatal injections. Maxillary or second division nerve blockThough rarely necessary, it should be considered when other techniques prove inadequate because of infection accompanied by inflammation. This block provides anesthesia of the entire maxillary nerve peripheral to the site of injection, pulp of all maxillary teeth on the side of injection,

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buccal soft tissues and bone; hard palate on the injected side, upper lip, cheek, side of the nose and lower eyelid. 2) Mandibular anesthesia – Mandibular pulpal anesthesia is normally achieved through the inferior alveolar nerve block. Additionally, anesthesia of the buccal soft tissues and bone anterior to the mandibular molars is provided. The lingual nerve is usually anesthetized along with the inferior alveolar nerve. It provides anesthesia in the anterior 2/3 rd of the tongue, the floor of the oral cavity and the mucous membrane and mucoperiosteum on the lingual side of the mandible. A successful inferior alveolar and lingual nerve block provides anesthesia to all mandibular tissues except the buccal mucous membrane and mucoperiosteum over the molars. To achieve anesthesia of this region, the buccal nerve block must be administered. Incisive or mental nerve block: The incisive and mental nerves are terminal branches of the inferior alveolar nerve, arising at the mental foramen. This provides sensory innervation to the skin of the lower lip and chin and the mucous membrane lining the lower lip, also, the incisive nerve remaining within the mandibular canal provides sensory innervation to

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the pulps of premolars, canine and incisors and the bone anterior to the mental foramen. Mandibular nerve block: A true mandibular block injection provides adequate anesthesia of all sensory portions of the mandibular nerve (buccal, inferior alveolar, lingual and mylohyoid). This can be achieved through the Gow Gates techniques involving the lateral side of the neck of the mandibular condyle below the insertion of the lateral pterygoid muscle. Akinosi or closed mouth technique: This is indicated when opening of the mandible is limited owing to infection, trauma or trismus. Additional local anesthetic techniques: 1) Periodontal ligament injection: The PDL injection is frequently used when isolated areas of inadequate anesthesia are present. It is also indicated to achieve anesthesia in a single mandibular and / or maxillary tooth. Advantages include adequate pulpal anesthesia with a minimal volume of solution (0.2-0.4ml) and absence of lingual and lower lip anesthesia. 2) Intraseptal infiltration (variation of intraosseous) – Here the 27gauge 1-inch needle is inserted into the interseptal tissue in the area to be anesthetized. Its success rate is not so high. It is relatively more successful in young patients due to decreased bone density. 16


3) Intrapulpal injections – Though rarely indicated in operative procedures, intrapulpal technique may be used to achieve pain control when pulp chamber of a tooth is exposed. The needle is firmly wedged into the canal to a snug fit and the solution administered under pressure. 4) Intraosseous injection – Though rarely employed since the acceptance of the PDL injection, the intraosseous injection can be effective in producing anesthesia adequate to permit certain operative procedures. To administer an intraosseous injection, the dentist must anesthetize the soft tissues and bone overlying the apical region of the tooth through local infiltration. Effect of Local Anesthetics on the pulp: A special consideration here must be given to the action of local anesthetic with a vasoconstrictor on the health of the pulp organ. The purpose of adding a vasoconstrictor to LA is to potentiate and prolong the anesthetic effect by reducing the blood flow in the area to which it is administered. However, at the same time it causes a significant decrease in pulpal blood flow although the flow reduction lasts a relatively short time.

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There is a direct relationship between the length of flow cessation and the concentration of the vasoconstrictor used. Increased concentration of epinephrine causes a longer cessation of pulpal blood flow. Researchers have reported that pulpal blood flow returned to normal levels after 3 hours of total cessation of blood flow. Presumably, irreversible pulp damage resulting from tooth preparation is caused by the release of substantial amounts of vasoactive agents (substance P) into the extracellular compartment of the underlying pulp. Under normal circumstances, these vasoactive substances are quickly removed from pulp by the blood stream but when blood flow is decreased these substances are accumulated along with other metabolic waste products thus damaging the pulp. Therefore wherever possible, it is advisable to use vasoconstrictor free LA for restorative procedures on vital teeth. 8) Inhalation or Conscious Sedation: Conscious sedation and inhalational analgesia are now accepted modalities of pain control. Various pharmacotherapeutic agents have been advocated. Myriad chemicals that have been proposed are barbiturates, psychosedative drugs like phenothiazine derivatives, propyl alcohol derivatives, benzodiazepine derivatives, and narcotics like morphine but the most popular and widely used is nitrous oxide

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and oxygen inhalational analgesia. This technique basically relies on elevation of pain threshold. Nitrous oxide and oxygen in a controlled combination produce highly effective sedation. Concentrations of 35-40% produce enhanced sedative effects and are the recommended concentrations and produce its peak effect in 3-5 minutes. Being inert, it does not combine with any body tissue and is eliminated unchanged through the lungs is less than 5 minutes. However, the use of this technique requires elaborate equipment and care during administration. 9) Hypnosis and psychotherapy – Hypnosis is a sleep-like state with persistence of certain behavioral responses. The subject is susceptible to and may respond to the hypnotic suggestions concerning aspects of behavior, environment, memory etc. It has been used in various modalities in medicine and dentistry to alter responses to pain. It is currently used to define an area of research and treatment that employs suggestion. The long history of hypnosis with various contributions is testimony to its effectiveness. Combined with other techniques, it is a powerful tool. The dentist and the patient may derive certain benefits: The dentist has the opportunity to work on a more relaxed and cooperative patient while the patient is less fatigued with no specific recollection of having experienced discomfort. The operation must have 19


a through knowledge of the mechanics of hypnosis and the associated psychological, emotional and mental factors as well as the principles associated with hypnosis. Posthypnotic suggestion has also been proposed as a way of alleviating certain noxious dental habits. Other psychological techniques include psychotherapy, operant conditioning, biofeedback, systematic deconditioning and relaxation techniques. Biofeedback deserves mention as an interesting adjunct to pain control. Its principal aim is the control and regulation of disordered nervous system behavior. The therapeutic applications usually translate to the direct control and elimination of the symptom. Hirschman and coworkers reported success in lowering dental phobia and pain perception and anxiety levels with a procedure that used forearm extensor EMG biofeedback during dental treatment. Its mastery and effectiveness await further research and trials. 10) General anesthesia: This technique involves complete transient reversible of consciousness. Various agents like ether, halothane, Fentanyl with Domperidone etc are utilized. It is employed as the last report and this finds rare application in dental pain control. The various stages of anesthesia as described by Guedal is 1957 are:

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Stage I – Analgesia. Stage II – Excitement. Stage III – Surgical anesthesia Plane I Plane II Plane III Plane IV Stage IV Overdose General anesthesia is a highly specialized field and requires the assistance

of

medical

specialists

and

preparatory

equipment.

Preanesthetic evaluation and medication have to be charted into the treatment plan. Its use is reserved for highly demanding cases. Role of medication in pre and postoperative pain control: Most of the patients suffering from pulpitis are likely to have been taking oral analgesics. NSAIDS can be used to control patient discomfort postoperatively or preoperatively as well as for possible placebo effect. Their myriad range from acetylsalicylates to ibuprofen, and the latest COX-2 inhibitors afford a huge array of medicaments to choose from.

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Advances and Newer concepts in pain control: 1) Newer, better acting local anesthetics with fewer side effects and better safety profile like confbuinidine and repivacaine may change the pharmaceutical range of anesthetics used in future. Also alterations to local anesthetic profile like EMLA (Eutectic mixture of local anesthetics) which allows profound topical anesthesia and pH alteration to make administration more comfortable as well as hyaluronidase to permit better penetration are but a few of the research modalities. 2) Electronic dental anesthesia – The use of electricity as a therapeutic modality is not really new dating back to 40 A.D. but momentum in this field gathered since the 1960s when TENS was introduced into medicine and EDA was proposed for dentistry. The mechanics differs for chronic and acute pain. Basically low frequency setting of 2Hz and higher frequency of 120Hz for chronic and acute pain is used which produces changes in blood serotonins, Ltryptophan, endorphins, and enkephalins. Also the gate control theory is employed upon for acute pain control. In dentistry, it has found applications in Myofacial pain dysfunction syndrome, acute dental pain for restorative and prosthetic procedures,

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adjunct to local anesthesia and as an aid in its administration and reversal of LA. It is basically administered with use of electrodes. Low frequency of 2.5Hz for 40-60 minutes is used for chronic pain while high frequency of 120Hz is employed for restorative procedures adjusting the controller and maintaining the electronic pad positions for various teeth and procedures. At present, it is basically indicated as an adjunct to local anesthesia and future prediction for use in all spheres of dentistry exists. It is contraindicated in cardiac pacemaker patients, neurological disorders, pregnancy, maturity etc. While advantages of no needle or infection exist the cost, training and experimental nature of the modality are the drawbacks. Presently available systems include Cedata, H-wave and 3M patient comfort system. Only future research will show which way this technique progresses. 3) Alternative tooth preparation – These include the modality of air abrasion, lasers, ultrasonics and chemomechanical means. Air abrasion utilizes micron sized particles to remove tooth structure. It is relatively more comfortable but has the disadvantage of lack of control and has not caught the popular imagination. Lasers are now available for hard tissue lasing and are reported as painless, 23


noiseless and highly patient friendly. However, it is still under research and the cost too is highly prohibitive. 4) A new treatment modality that promises to revolutionize the way we look at operative dentistry also promises to eliminate pain completely. This involves the use of ozone as a means to sanitize carious lesions and employ remineralization techniques to regenerate tooth structure with minimal, if any, restorative procedures. Kavo’s Healozone is a novel, experimental device under trial. Only time will tell, if it will deliver on it promises. Newer techniques and ideas are being constantly researched upon to achieve the ideal. CONCLUSION: “No pain, no gain”, goes the old axiom; however, it can be modified in modern dentistry to state “no pain, all gain”. The application of ideal techniques and procedures with expertise and an attitude of empathy and understanding will help the clinician control and eliminate this highly unwelcome stimulus to achieve greater efficiency and highly contented individuals. Remember, “to the whole world you might just be one man, but to one man you just might be the whole world.” That one man is the individual who comes to us for relief-OUR PATIENT.

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BIBLIOGRAPHY 1) Local anesthesia and pain control in Dental practice – Monheim. 2) Anesthesia A to Z – Yentis, Hirsch, Smith. 3) Handbook of local anesthesia – Stanley Malamed. 4) Sturdevant’s art and science of operative dentistry. 5) Operative Dentistry – Marzouk. 6) DCNA – Anesthesia in dentistry – April 1999. 7) DCNA – Dental Phobia and Anxiety – October 1988. 8) Operative dentistry by G.V. Black.

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Pain control in operative dentistry 2/ dental implant courses by Indian dental academy