What Is Pain and Its Physiology?
Pain is an unpleasant sensation associated with or without tissue damage. Pain is perceived when the signals travel from the nerve fibers to the brain denoting that something hurts or is unpleasant. Nerve conduction refers to the passing of electric current through the nerve fibers. The nerve cell membrane is a thin elastic covering composed of a layer of lipids between two layers of protein. There are various theories of pain like specificity theory, pattern theory, and gate control theory.
What Are the Characteristics of Pain?
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Threshold and Intensity - The sensation of pain is felt after a particular threshold is crossed.
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Adaptation - Pain receptors do not adapt even if the sensation of pain lasts for a longer duration.
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Localization of Pain - Generally, pain is not well localized.
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Emotional Accompaniment - Pain is not a pure sense and is accompanied by other sensations.
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Influence of the Rate of Damage on the Pain Intensity - Greater the rate of tissue damage, the greater the pain intensity.
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Pain Pathway - The trigeminal nerve is responsible for the transmission of pain sensation in the head and face region.
What Is the Biological Basis of Orthodontic Therapy?
Tooth movement is essentially a PDL (periodontal ligament) phenomenon. The fibers of the PDL are arranged in such a way as to resist the extrusion of the teeth under masticatory forces. The response to sustained force against the teeth is a function of force magnitude.
Lighter forces are compatible with the survival of cells in the PDL and remodeling of the tooth socket by a relatively painless ‘frontal resorption,' which is good for orthodontic treatment. Heavy forces lead to rapidly developing pain, necrosis of the cellular elements in the PDL, and the phenomenon of ‘undermining resorption’ of alveolar bone near the affected tooth, which is bad for orthodontic treatment.
Prostaglandins and Orthodontic Tooth Movement - Prostaglandins are chemical messengers belonging to the family of Eicosanoids, which are derived from Arachidonic acid. Enhanced bone resorption and elevated body temperature are responsible for pain and inflammation. Orthodontic forces increase the synthesis of prostaglandins (PG), which increases osteoclastic resorption. Increased levels of PGE2 (prostaglandin E2) are seen in the alveolar bone where orthodontic forces are applied.
What Is the Etiology of Orthodontic Pain?
The causes of periodontal pain are pressure, ischemia, inflammation, and edema. Immediate pain response is due to the compression of the PDL during archwire placement. Delayed response, which occurs a few hours later, is due to the hyperalgesia of PDL.
Perception of Pain in Patients Undergoing Treatment - Patient discomfort with fixed appliances is associated with the placement of archwires or separators. First signs of pain are seen approximately 4 hours within the placement of wires or separators. Discomfort peaks about 24 hours, and decreases in about 7 days. The placement of separators causes pain in the posterior teeth and the archwire placement causes pain in the anterior teeth. Pain correlates with the presence of Substance P and Prostaglandins in the PDL.
What Are the Different Types of Orthodontic Pain?
A) Depending on the Degree of Pain Perception -
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First Degree - The patient is not aware of pain at the start unless the orthodontist manipulates tooth movement.
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Second Degree - This refers to pain occurring during biting hard or clenching the teeth.
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Third Degree - With this type of pain, the patient might not be able to masticate routine food.
B) Based on Time of Onset -
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Immediate - Associated with the sudden placement of heavy forces on the tooth.
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Delayed - Produced by a variety of forces which varies from light to heavy and this type of pain response decreases with time.
What Are the Orthodontic Procedures That May Cause Pain?
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Band pinching on unseparated teeth.
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Separator placement.
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Initial archwire placement.
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Placement of E-chains and heavy elastics.
1) Separation of Teeth - Banding of the teeth is the first step in fixed orthodontic treatment. For the banding of teeth, space is created on either side of the tooth by placing separators and it is a well-known fact that this results in a painful experience in most patients.
2) Placement of Arch Wire and Activation - This is one of the major causes of pain. Pain duration starts after around 4 hours of placement and generally peaks around 24 hours of activation, lasts for 2 to 3 days, and then gradually decreases in its intensity around the fifth or sixth day. A diurnal variation in pain experienced by patients with evenings and nights.
3) Application of Orthopaedic Forces and Expansion of Arches - This force leads to tissue displacement, deformation, and development of internal stress characterized by acute inflammation, traumatic tears, and disruption of collagen fibers. An inflammatory process that gives painful sensation to patients is expressed in the whole craniofacial region. The pain decreases sharply after around 3 days. It is experienced during headgear wear.
4) Debonding Tooth Mobility and Force Application - These are the two important influencing factors for pain during the debonding procedure. There are various studies that suggest that applying intrusive force during debonding causes less pain and discomfort as compared to mesial, distal, lingual, extrusive, or outward direction. Also, asking the patient to bite on a cotton roll or applying finger pressure can minimize the intensity of pain.
How Does Orthodontic Pain Affect Patient Compliance?
Discomfort caused by orthodontic appliances may significantly affect patients’ compliance with treatment. Pain is the major reason for avoiding the use of elastics by patients, maintenance of oral hygiene, and premature termination or incomplete follow-up of the treatment. It is a well-known fact that an individual’s ‘Physiological and Psychological Susceptibility’ is a significant factor in the intensity of tissue discomfort and is caused by the physical effects of appliances on patients' minds and bodies. Hence, discomfort during treatment is not totally because of force only but because of the psychology of the patient also.
What Are the Techniques Used for Managing Orthodontic Pain?
Various techniques have been suggested for the management of orthodontic pain, they are:
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Use of Non-steroidal Anti-inflammatory Drugs (NSAIDs) - Preoperative analgesics are administered one hour before the procedure to manage the pain.
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Anesthetic Gel - The use of anesthetic gel is an entirely painless procedure. It may be useful in performing various orthodontic procedures like band cementation and removal, bracket removal, and archwire ligation. The advantage of using anesthetic gel is that it can be used easily and directly in the gingiva.
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Bite Wafers - Bite wafers will displace the teeth temporarily and allow blood to flow in the areas that are compressed, which will prevent a build-up of metabolic products and the rhythmic behavior of chewing inhibit nociceptive responses. Bite wafers and gum chewing must be instituted before the pain sets in, that is, within the first 8 hours after activation. And this method would be ineffective if the teeth become too tender for repetitive chewing.
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Low-Level Laser Therapy - Low-level laser has been shown by many investigators to produce analgesic effects in various therapeutic and clinical applications.
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Transcutaneous Electrical Nerve Stimulation (TENS) - A form of stimulation that produces analgesia, TENS is delivered via surface electrodes placed over the painful area or within the nerve innervating the painful area's distribution.
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Vibratory Stimulation - Marie et al. reported the use of vibratory stimulation to manage orthodontic pain in the year 2003. Vibratory stimulation should be done before the onset of pain for it to work effectively.
Conclusion:
Pain is the major reason for patients not going through the full course of their orthodontic treatment. Doctors often concentrate less on managing the pain during orthodontic treatment. But understanding the reason for pain and helping the patient in managing it can help with a better overall outcome in the treatment.