Pain control

Pain control in operative dentistry

Pain is one of the most commonly symptoms in dentistry.
Pain: An unpleasant sensory or emotional experience associated with actual or potential tissue damage. Pain can be described as sharp, burning, aching, cramping, dull or throbbing as human emotions. Recognition of irritant to the tooth gives the patient an opportunistic to correct the problem before irreversible effect can occur, this recognition occurs because of pain receptors in the pulpodentinal complex are linked to the CNS by afferent pathway.
Electrophysiology of nerve conduction:
In unstimulated nerve (nerve membrane in a polarized state), a nerve possesses a resting potential (-ve electrical potential of -70 mv), in this state interior of the nerve is –ve relative to the exterior (Na+ outside & K+ inside the nerve membrane).
When a stimulus is applied to the nerve, the nerve membrane alter its permeability, so that permit Na+ to diffuse through membrane into nerve cell (depolarization of the membrane from its resting level to its threshold potential or firing threshold (+ 40 mv), in this state interior of the nerve is +ve relative to the exterior. The entire depolarization precess requires 0.3msec..
After depolarization, the repolarization will be occurred, the permeability of the nerve membrane again decrease to Na+ and K- move toward outside nerve cell and restoring original electrochemical equilibrium -70 mv. The entire precess of repolarization requies 0.7 msec..
Noxious stimulations transducer by nociceptors (sensory nerve endings that mediate pain into nociceptive impulses).
The propagated impulse travels along the nerve membrane toward the CNS, the spread of this impulse depending on whether or not a nerve is myelinated:
Unmyelinated nerve: Slow forward creeping process, impulse travel in 0.5-2 m/sec speed. (C fibers)
Myelinated nerve: Salutatory conduction process, impulse travel in 14.8-120 m/sec speed. (A-alpha & A-delta fibers)
Pulp pain:
Dentinal sensitivity is a result of direct stimulation of sensory nerve ending in the dentin.
Odontoblasts, are sensory cells through their processes in the dentinal tubules, odontoblasts receive and transfer stimuli to nerve endings in the pulp.
Dentinal sensitivity is a result of mechanical stimulation of free nerve ending in the pulp caused by rapid fluid flow in the dentinal tubules when the dentin stimulated.

The dual nature of pain:

Pain perception: Physio-anatomical process where by an impulse is generated following application of an adequate stimulus & is transmitted to the central nervous system.
Pain reaction: is a psycho-physiological process that represents the individuals' overt manifestation of the unpleasant perceptual process that just occurred.


Control of pain:
One of the most important aspects of the practice of dentistry is the control or elimination of pain.
Techniques for the elimination of pain, including a traumatic needle injection, have been available for years and are essential to a successful dental practice.

How we can obtain effective anesthesia:

Knowledge of patient anatomy.
Physical and emotional status (smoker, drinker, nervous input).
Understanding the effect of drug.
Advantage & disadvantage of adding vasoconstrictor.
Benefit of local anesthesia:
To eliminated pain.
To reduce salivation
Patient cooperation.
Hemostasis (vasoconstrictor).
Operator efficiency.

Properties of desirable L.A:

Should not be irritating to the tissue to which it is applied.
Should not cause permanent alteration of nerve structure.
Low systemic toxicity.
Must be effective.
Short time of onset of anesthesia.
Have enough duration of action to permit completion of dental procedure.


Active form of local anesthesia:
L.A compounds of both uncharged fat-soluble base (RN) & + vely charge water-soluble (RNH+) cation in equilibrium with each other.
L.A possess both lipophilic and hydrophilic forms.
L.A classified as either amino esters or amino amides according to their chemical linkages.
Local anesthesia are alkaloid bases that are combine with acid usually hydrochloric acid to form water- soluble salts.
PKa is constant for each type of L.A solution & it rang from 7.5-10 (The PH at which compound is half in the ionized & half in the unionized state).
The PH of L.A & tissue into which its injected influence its nerve-blocking action.

Mode & site of action of local anesthesia:

The nerve membrane is the site at which L.A exert their pharmacological actions.
Uncharged fat-soluble form responsible for optimal diffusion through the nerve sheath.
Charge cation binding to the Na+ channel receptors.
This produce blockade of Na+ channel.
Decrease of Na+ conductance.
Depression the rate of electrical depolarization.
Failure to achieve threshold potential level.
Lack of development of propagation action potential.
Conduction blockade.
10. Acidification of tissue ↓ L.A effectiveness, the inflammatory process produce acidic products, the PH of normal tissue is 7.4 the PH of an inflamed area is 5-6 this will interfere with the liberation of free base.

Vasoconstrictors:

L.A without vasoconstrictor produce vasodilatation →bleeding at the site of injection, ↑rate of absorption from the injected site →↓ duration of action & ↑blood level →↑likelihood of producing toxicity.


A therapeutic dose: Is the smallest amount of drug that is effective when properly administered and does not cause adverse reactions.
An overdose: Is an excessive amount of drug that results in an overly elevated local accumulation or blood level of the drug, which causes adverse reactions.

Patient condition and local anesthesia:

Systolic pressure more than 200 & diastolic more than 115 should not receive local anesthesia.
Resting patient with pulse rate less than 60 or more than 110 should be questioned.
CNS more affected than CVS.
Minimum or moderate over dose cause depression, apprehension, sweating, ↑ blood pressure, ↑ heart rate,↑ respiratory rate, drowsiness.
Moderated to high overdose cause tonic-clonic activity followed by generalized CNS depression,↓ blood pressure,↓ heart rate less than 60 beat/min,↓ respiratory rate and respiratory arrested.
Allergy to local anesthesia, contraindicated to injection →anaphylactic shock.
Duration of anesthesia: Considerations factors exist that affect both the depth and the duration of a drug's anesthetic action:
1. Individual variation in response to the drug administered.
2. Accuracy in administration of the drug.
3. Status of the tissues at the site of drug deposition (vascularity, pH).
4. Anatomic variation.
5. Type of injection administered (infiltration, nerve block).

The selection of a L.A. for use in a dental procedure should be based on the following criteria:
1. Duration of the dental procedure.
2. Requirement for hemostasis.
3. Requirement for post-surgical pain control.
4. Contraindication to the selected anesthetic drug or vasoconstrictor.


Local anesthetics techniques:
Infiltration anesthesia: is commonly used in maxillary teeth, because of the ability of the anesthetic solution to diffuse through periosteum and the relatively thin cancellous bone of the maxilla.
Infiltration anesthesia is rarely effective in the adult mandible because of the inability of the anesthetic to penetrate the more dense cortical plate of bone.
Regional Nerve Block: Nerve block is defined as a method of achieving regional anesthesia by depositing a suitable local anesthetic close to a main nerve trunk, preventing afferent impulses from traveling centrally beyond that point.

Maxillary anesthesia:

Maxillary nerves that can be anesthetized and are of importance in endodontic procedures are the maxillary (V2), posterior superior alveolar (PSA), anterior superior alveolar (ASA), greater palatine, and nasopalatine nerves.

Mandibular anesthesia:

Pulpal anesthesia of mandibular teeth is traditionally obtained through the Inferior alveolar nerve block.
Incisive nerve block: The incisive and mental nerves are terminal branches of the inferior alveolar nerve arising at the mental foramen.

Additional local anesthetic procedures:

1. Intraligamentary injection: It placed into the periodontal space between the root of the tooth and the interseptal bone.
It is frequently used in restorative dentistry when isolated areas of inadequate anesthesia are present. It may also be used alone to achieve brief, profound pulpal anesthesia in a single tooth with a minimal volume of anesthetic (0.2 to 0.4ml), also the absence of lingual and lower-lip anesthesia.
2. Intraseptal injection:
Because of decreased bone density, intraseptal anesthesia is more successful in younger patients. The needle must be advanced firmly into the cortical plate (interproximal) bone, the soft tissues having been anesthetized (either by infiltration or topical application) before needle insertion.
3. Intraosseous anesthesia:
The system consists of a perforator, a solid needle that perforates the cortical plate of bone with a conventional slow-speed, contra-angle hand piece, and an 8-mm long, 27-gauge needle that is inserted into this pre-drilled hole for anesthetic administration when periapical or periodontal infection is present on the tooth to be treated.
4. Intrapulpal injection.
When the pulp chamber of a tooth has been exposed pathologically or while making an access opening, the intrapulpal injection may be used in addition to local infiltration or block anesthesia to achieve adequate pain control, significant resistance is encountered and the solution must be inserted under pressure.


Anxiety control:
Many patients are psychologically unable to withstand dental care even though operative pain is controlled with L.A..
Stress-induced problems including angina pectoris, seizures, acute asthmatic attacks, hyperventilation, cardiac arrest, myocardial infarction, acute pulmonary edema, cerebrovascular accident, acute adrenal insufficiency, and thyroid storm.

Local anesthesia: Elimination of all sensation especially pain in one part of the body by the topical application or regional injection of a drug.
Analgesia: Elimination of pain in conscious patient.
Benefit of sedations:
Altered the patient's mood.
Patient remain cooperative.
Elevated patient threshold.
Maintain patient with protective reflex action.

Routes of administration: (nitrous oxides, barbiturates, psycho sedative drugs, narcotic)

Inhalation (nitrous oxides).
Oral administration.
Parenteral administration (IM, IV, SC).

Post operative pain control:

Post operative pain: It is acute pain & it is an unpleasant sensory perceptual & emotional experience that is produced by nerve irritation related to tissue damage caused by surgical intervention. Anti-inflammatory reduce the availability of prostaglandin →↓ pain.
(aspirin, acetaminophen, Ibuprofen, mefanamic acid, morphine, codeine).


Referred pain: The sensation is interpreted as coming from one area, although it actually originates elsewhere, thus the pain of angina pectoris is often felt in the left arm.
Referred pulpal pain:
Frontal (forehead) → Max. incisors
Nasolabial area → Max. canines
Max.region above Max. molars → Max 2nd premolars, Max 1st molars
Temporal region → Max.2nd premolars
Ear → Mand. Molars
Mental region of Mand. → Mand. incisors, canines, premolars
Angle of mand. → Mand.1st &2nd molars
Superior laryngeal area → Mand. 3rd molars
Max. premolars → Max. canines
Max. molars → Max. canines, Mand. Premolars
Mand. Premolars → Max. canines & premolars
Mand. 1st premolars → Mand. 1st &2nd molars

Pain disorders that mimic odontalgia:

The anatomic sites that must be evaluated in patients who complain of pain that does not appear to be of an odontogenic origin include the following:
Periodontium (periodontalgia).
Masticatory musculature (myalgia).
Jaw joints (arthralgia).
Salivary glands.
Sinus linings.
Middle ear (otalgia).
Associated nerve or vascular structures.


Psychogenic pain: Unpleasant sensation that has no organic basis it is originated wholly within the mind.
Neurogenic pain: Sharp, burning & intense, may be constant or intermittent.
Vascular pain: Diffuse, may be referred & thus difficult to localize.
Muscle pain: Dull, limited to the area of origin.