Dental pain is the second most sever pain patient feel. The first being that of renal colic

Pain is unpleasent sensation felt and precived by the patient. It is a subjective symptom in which the clinician must relay on the description of the patient for his pain. Pain, pleasure and happness are simple ideas incapable of definition.

Pain is the most common reason for a patient to visit thee dental clinic. In most cases the cause of this pain is odontogenic and obvious. The dentist usually can manage successfully the disease process through dental therapy.  However, in some cases nonodontogenic neurologic disorders may be the cause of this pain.

Examination of Facial Pain

Examination of facial pain regarding its type, severity, onset and other aspect is a very important factor for proper diagnosis and mangament.

• Pain character: Pain may be described as dull, sharp, throbbing, burning, .....etc. Patients with psychosomatic pain usually give a bizzare discription for their pain as icy cold, red-hot and others.
• Severity of pain: Pain severity is difficult to be estimated accuretly. However, the relief offored by analgesic drugs of different potency may be an indicative for the degree of pain severity. Interfere with sleep is also a reliable guide to pain severity.
• Pain continutity and remession: Pain is rarely absolutely continous, for even the most sever type of pain is usually occasionly relieved by short periods of remession. Only patients with spychosomatic pain describe it as being continous without any remission.
• Is the pain increassing or decreasing in severity:  Increasing pain obviously require urgent investigations while decreasing or improving pain, on the other hand, allow sometime for the investigation to be undertaken.
• Place of maximum intenisty and area of spread: The point of maximum intensity is determined by asking the patient to detect the point that hurts him most. The pain usually spread from the point of maximum intensity to involve the surrounding area to a greater or lesser extent.

Area to which pain radiates:

• Pain of coronary thrombosis is usually substernal and radiates to the left shoulder and forearm and sometimes the left side of the mandible.
• Pain of carcinnoma of the side of the tongue usually radiates to the ear of the same side.
• Hystrical pain may be described to radiates to areas to which it would be anatomically impossible, as crossing the midline to radiates to the opposite side. Pain may radiates from one jaw to anther in the same side.
• What make the pain worse?
• Pain in trigeminal neuralgia may be initiated by light touch to the trigger zone in the face.
• Pain of dental origin is usually intiated by hot and cold food or drinks.
• Pain produced by bitting, bending, lowering the head, straining and jamming movements is suggestive for acute maxillary sinusitis.

Associated symptoms: Local symptoms as intra- or extra-oral swelling, discharge, bad taste or pain or discomfort on swallowing may be indicative.

Classification of Pain Disorders

Pain can be classified, from the functional view point, into neuritis, neuropathy, neuralgia and neurosis or psychalgia.

Neuritis:Neuritis is defined as a pain disorder that results from a nervous system response to localized, irritative, nonneural disease. The term neuritis should only be used whrn inflammation is strongely thought to be the cause of the pain. The cause of this type of pain is usually associated with diseases of the glands, cavitis, muscles or bones through which nerves tranverse or innervate. Examples of causes of nuritis are odontgenic pain (pulpitis) as pulpitis, sinusitis, postextraction ostties and gingivitis.

Neuropathy: Neuropathy is defined as pain disorder that results from the nervous system response to systemic disease that is associated with peripheral neural dysfunction.(Table 1). The condition is associated with a systemic disease that precedes a neural response. This type of pain is characterized dull aching or burning sensation that is often continous.

Table 1. Some examples for neuropathy. 

• Collagen-vascular disorders as lupus.
• Neutritional disorders as hypervitaminosis.
• Metabolic disorders as diabetes.
• Idiopathic as burning mouth syndrome.

Neuralgia: Neuralgia is defined as a pain disorder that results from primary nervous system disease and in which nonnociceptor stemuli elicit pain. Neuralgia means pain along the course of a nerve. The pain usually have an inciting cause, quite sudden in onset, lasts only for seconds or minutes and it may occur in paroxysms (sudden violent attack). There is no objective sensory changes except for the occassional hyperaesthesia in the peroid immediately following the attack. The nerve is not tender along its course. Major neurologic pain is unique in character and is characterized by:

• Limited to those cranial nerves having somatosensory components.
• Abrubt in onset.
• Sever shooting and lancinating in nature and may be preceeded by minor sticking or electric shock sensation that lasts for only few seconds.
• Paroxysmal in character and the attack lasts usually for 30-60 seconds.
• Pain is limited to the distribution of the nerve involved.
• Trigger mechanism with a trigger zone that vary in size and site.
• Subject to unpredictable remission and excerbation.
• The etiology of the condition is unknown.

Neurosis Or Psychalgia: Psychalgia is defined as pain disorder that results from psychotic disease in which pain hallucination occurs in the absence of  a related nociceptor stimulus. Usually pain is of great magnitude and inappropriate with the cheif complaint.

 For differential diagnosis of facial pain, pain was classified into three categories regarding the etiology of the pain. These are pain due to local causes, pain arising in the nerve trunk and central pathway and refered pain.

Pain Due To Local Causes

A. Pain Originating In Teeth And Jaws

• Teeth hypersensitivity and pulpal pain: Teeth hypersensitivity is usually due to the presence of exposed dentine or cementum. Pulpal pain, on the other hand, is due to involvement of the pulp in a carious process. In hypersensitivity pain is precipitated by hot, cold and sweets. Pain is localized, sharp, sever and lasts for only few seconds after removal of the stimulus. Pulpal pain is more sever and is throbbing in nature and lasts for longer period of time after removal of the stimulus.
• Acute inflammatory pain: Acute inflammatory conditions such as dento-alveolar abscess, periodontal abscess and pericoronitis are usually associated with sever pain which may radiates to remote areas. Conditions such as dry socket and early stages of osteomyelitis are associated with sever pain. In acute maxillary sinusitis pain is centered on the cheek and radiates to the supraorbital region. Pain may appears to originate in the upper teeth related to the affected sinus as their nerve supply passes through the sinus walls. Characteristically sinusitis pain is worse in the morning and evening and by lowering the head.
• Dull pain: Dull pain represent the greatest difficulty in diagnosis. Local causes of dull pain are so many. Almost any local pathological condition, starting from remaining roots, and impacted teeth to benign and malignmant neoplasms may cause dull pain at some time in the course of the disease.

B. Pain Originating In The Temporo-mandibular Joint

Pain in the temporo-mandibular joint may result from myofacial pain dysfunction syndrome or from arthritis.

• Myofascial pain dysfunction syndrome: Pain is dull ache that may be limited to the joint or radiates to the jaw and ear as well as the temple region. There is alteration in the mandibular movements and tender painful muscular areas can be usually detected by palpation.
• Arthritis: Pain is generally confined to the joint but may radiate to the ear and temple. However, clinical and radiographic examination reveal intra-articular joint changes.

Pain Arising In Nerve Trunk And Central Pathway

A. Pain with no abnormalities in the nervous system

1. Idiopathic Neuralgia

• Trigeminal neuralgia: The condition is characterized by the presence of a classic diagnostic symptoms. These symptoms include the presence of trigger zone mechanism, and the unilateral occurrence. Trigeminal neuralgia will be discussed in details in chapter 10.
• Glossopharyngeal neuralgia: It is a rare disease of unknown etiology that is seen mostly in old age. Clinically it may be of two types, otic or pharyngeal. The attack is characterized by unilateral shooting pain that strikes the internal ear, soft palate, pharynx, nasopharynx, tonsillar fossa and sometime the posterior one third of the tongue. Trigger zone include tonsils, pharynx or posterior one third of the tongue. Pain may be initiated by talking or swallowing when food passes over the trigger area. Treatment modalities include vitamin B therapy, Tegratol administration and glossopharyngeal nerve sectioning either extra or intra cranial.
• Sphenopalatine neuralgia (Cluster headache): The condition is characterized by attacks of sever pain which occur spontaneously at irregular intervals. The attack lasts for a period ranging from few minutes to days. Pain is unilateral over the regions of the eyes, maxilla, teeth, ear, mastoid process, base of the nose and/or temporal and zygomatic regions. There may be tinnitus and vertigo. Characteristically there is no trigger zone.
• Superior-laryngeal neuralgia: It is characterized by sever pain in the upper part of the larynx that may radiates to the zygomatic region and ear. Pain comes suddenly and is trigged by pressure on the thyrohyoid membrane or propping on the pyriform fossa.
• Facial nerve neuralgia (Geniculate ganglion neuralgia): The condition is characterized by intense attacks of deep pain in the ear. Pain extends anteriorly to the tragus and posteriorly to the mastoid process. The attacks are precipitated by percussion over the facial nerve but not affected by the functional movement of the jaw.

2. Atypical Neuralgia

• Psychogenic neuralgia: The distribution of pain is non-anatomical, it may involves portion of sensory supply of two or more nerves. There is no trigger zone and pain may cross the midline. The pain is described as being constant, which persists for weeks, months or years. The patient is unable to localize the pain and give uncertain distribution for his pain.
• Organic neuralgia: This may be due to dental diseases, neoplasm, vascular diseases (vascular neuralgia). Vascular headache or facial migraine characterized by unilateral attacks of sever pain that lasts for 30 minutes or many hours. Pain starts at night at specific hour (alarm clock feature) The patient is left exhausted after the attack. The condition is due to vascular constriction of the facial arteries followed by vasodilatation.

B. Pain with abnormalities in the nervous system

1. Extra-cranial lesions

The extra-cranial lesions that may cause facial pain include the following:

• • Nerve involvment in an infection process.
• • Pressure on the nerve by an expanding lesion either benign or malignant or by compressed bone.
• • The development of a neuroma on a peripheral nerve either idiopathic or post-traumatic.

2. Intracranial lesions

The trigeminal nerved may be affected, either alone or with other nerves, by intracranial space occupying lesions as neoplasms or hematoma. The cardinal sings of trigemental involvement with an intracranial lesion are hypoesthesia within the area supplied by the trigeminal nerve and weakness of teh muscles of mastication.

Referred  Pain

Pain may be refrred to the facial region from painful conditions in the adjacent organs and some systemic diseases.

• Maxillary sinusitis: Inflammation of the maxillary sinus make the upper teeth, related to the sinus, sensitive to percussion. This is because these teeth are in close relation to the sinus floor and their nerve supply passes through the floor of the sinus. Characteristically pain of maxillary sinusitis is excerbated by bending, lefting, straining and jaming movements.
• Cervical spine and associated muscles: Cervical arthritis, bone spurs and myositis of the cevical muscles may refred pain in the maxillofacial region. However, this refred pain is only secondary to pain in the site of the original disease.
• Myocardial pain: Myocardial infarction or anigina pectrois produce pain in the chest that may radiates to the mandible. Some time such pain occurs without an associated chest pain. This may be an early indication to coronary ischemia.
• Salivary glands: Obstruction of the gland can produce sever pain due to destension of the gland capsule. This pain may be refered to the teeth.
• Muscles and fascia: Pain in the masticatory apparatus may resemble odontolagia or atypical neuragla pain.

Trigeminal neuralgia is the most common type of neuralgias. Incidence estimated to be one every 25000 adults. The condition occur without any apparant organic cause and it is characterized by classic diagnostic symptoms. (Table 2)

Table 2. Classical symptoms of trigeminal neuralgia.

• Paroxyamal attacks of pain which lasts for seconds or minutes.
• Provacation of the attack by gentel surface stimulation of the trigger zone.
• Pain is limited to the distribution of the branches of the trigeminal nerve.
• Unilateral occurance, pain never cross the midline.
• Lack of any sensory or motor nerve abnormalities.

Etiology

The etilogy of trigeminal neuralgia is unknown and even the site of the primary lesion is uncertain. However, many possible etiological factors have been suggested. These includes multiple sclerosis (a chronic disease of unknown etiology that result in damage of the myelin sheath of the nerves in the brain and the spinal cord), ischemia of the gasrian ganglion and dental etiological factors. The significance of teeth as an etiological factor has been suggested based on some observations which are listed in table 2.

Signs And Symptoms

Trigeminal neuralgia is considered as a disease of senility as it usually affect patients in the 5th or 6th decade of life. Females are more commonly affected than males. For unknown cause the right side of the face is much more commonly affected than the left side, while bilateral involvement is quite rare. The disease most commonly affect the mandibular or maxillary divisions of the trigmenal nerve more than the ophthalmic division.

Table 3. Clinical observations which suggest a dental origin of the trigeminal neuralgia.

• The common occurance of the disease in the second and third divisions over the first division.
• The characteristic localization of the trigger zone in the oral or paraoral regions in most cases.
• The remission of the paroxysmal attacks of pain following the extraction of teeth in some cases.
• The increased number of case reports which contributed the development of the disease to the presence of septic foci within the jaw bones.

Character of pain

Pain has an abrubt origin and the atacks lasts for seconds or few minutes.The attack could be initiated by slight afferent impulses to the trigger zones or may be evoked spontenously. Table 3 summurizes the character of trigeminal neuralgia pain. Usually pain raadiates to the tretories of the nerve involved. However, pain may be refrred to an area innervated by other division.

Trigger zone mechanism

The trigger zone represents the primary site of origin of pain. In some cases the trigger zone is pinpoint in size while in other cases it is more diffuse. In some cases the triggr zone is so hy[erirritable that the displacement of a single haire is suffeicent to evoke the attack. However, more commonly the attack is evoked by insignificant effort a chewing, drinking, yawing, talking, swallowing, touch or even an air draft. Mostly the trigger zone remains confined to a certain location but migration has been reported with long standing cases. Charaterixtically the patient points to the trigger zone with his finger without touching it to avoid pricipitation of the attack. This is called “Half-an-inch sign”.

Table 4. Charater of pain in trigeminal neuralgia.

• Abrupt onset.
• The attack lasts for seconds or few minutes.
• Pain is unberable, boring, burning, stabbing, sharp, shooting pain.
• Sometimes the attacks occur so rapidly that the patient complain of continous pain. that lasts for several minutes or hours.
• The attack could be evoked by slight atterent impulses from the trigger zones or may be evoked spontinously.
• Between the attacks the patient is completely free from pain but there is some discomfort. This is usually due to headack and some paraesthesia, sorness and feeling of pressure over the trigger zone.

Treatment Of Trigeminal Neuralgia

Medical Treatment

• Dialntin: This drug is used mainly for treatment of epilepsy. However the dose required to control the trigeminal pain is very near to the toxic level and can not be tolerated for an extended period of time.
• Vitamine B12: It offeres some relif of pain but faile to achieve sustain relief of pain.
• Tegratol (Carbamazepine): This ia an anticonvulsant drug that is used to control the convulasion attaks in epilepsy. It is used also for relief of pain of trigeminal neuralgia. The dose of the drug is increased gradually until the attacks no longer occur. The drug should be discontinued every three months and the patient is observed for any side effect. Side effects of tegratol include urtecaria and dermatitis, agranulocytosis, abnormalities of liver and bone marrow, drowsiness, dizziness and muscular incoordination.

Chemo-Surgical Treatment

The idea of this line of treatment is to place the a chemical as alcohol, local anaesthetic agent phenol or even boiling water in direct contact with the affected nerve. This will cause destruction of the nerve fibers and prevent the attacks of pain.

• Local Anaesthetic injection: Novacaine in oil emulsion is injected into the trunk of the nerve affected. Injection is repeated 6-7 times. It has a neurolytic action and thus prevent the occurance of the attacks.
• Alcohol injection: Alcohol 95% is injected to cause interruption of afferent impulses to the higer cortical center. This will produce prolonged anaesthesia. Alcohol may be injected peripherally near the trunk of the affected division or centrally into the gasserian ganglion.  Table 10-4 shows some comments on the peripheral alcohol injection.

Surgical Treatment

1. Peripheral Neurotomy

Pheripheral neurotomy, or post-ganglionic surgery, involves destruction or evulsion of the nerve at the mental, mandibular, infraorbital or nasoplatine foramen. This procedure is rlatively easy to be performed and carry no mortalitiy or morbidity. However, pain recurrence is mandatory with the regeneration of the evulsed nerves. Peripheral neurectomy is superior to alcohol injection as nerve regeneration takes longer time and no damage to the surrounding tissue occurs. The period of pain relief becomes longer with repeated neurectomies.

Lingual nerve neurectomy

• An incisionis made at the plica sublingualis just medial to the retromolar triangle thus the nerve is exposed as it crosses over the wharton’s duct.
• The lingual nerve at this site is large enough to be easily identified, graspped and evulsed.
• Infraorbital nerve neurectomy
• A U-shaped incision is made in the canine fossa and a mucoperiosteal flap is reflected upward to expose the infraorbital foramen.
• The nerve is then identified as it emergs from the foramend and grassped with a hemostate and evulsed. The entire trunk can be removed by winding it on the hemostate.

Inferior dental nerve neurectomy

Intra-oral technique

• Incision is made along the anterior boder of the ramus. The medial pterygoid muscle fibers are splitted and the nerve is located.
• Another incsion is made over the mental nerve which is exposed, grassped by a hemostate and evulsed.
• The inferior dental nerve is also divided at the mandibular foramen and then evalused out of the canal. This can be done by slowly rolling of the nerve on a hemoast.

Extra-oral technique

• Submandibular incision is made and the lateral surface of the ramus is exposed.
• A window is then cut on the cortes and the spongiosa to expose the canal. The nerve is then lifted up by a nerve hook and divided between two hemostats.
• The nerve is then evulsed very slowly from the canal.

2. Retrogasserian Rhizotomy

Retrogasserian rhizotomy is a preganglionic surgry which is performed intracranial. The sensory roots of the gasserian ganglion are selectively cut which result in permenant anaesthesia over the areas supplied by cut nerves.However, the procedure carry great risk of morbidity and mortality.

3. Nerve Decompression

This is an intracranial procedure in which an incision is made in the dura that surrounds the gasserian ganglion and its sensory roots. Gentel freeing of the gasserian ganglion and its sensory root results, for unknown cause, in pain elimination with retention of tactile and proprioceptive sensations.