Local anaesthesia is the commonly employed technique of achieving pain control in dentistry. The vital reasons why children dislike dental treatment is the fear and anxiety related to the injection of local anaesthetics. Painful dental operations cause fear, whereas fear and anxiety increase the amount of perceived pain. This review includes the certain different aspects of administration of local anaesthesia and recent procedures and devices for LA application in dental practice to achieve painless local anaesthesia in children.
The practice of contemporary dentistry is implausible without the use of local anaesthesia. However, it’s a paradox that the local anaesthesia procedure facilitates painless treatment in the mouth also causes discomfort and fear.
The distressing experience of needle is the cause for fear of dentist in children. Local anaesthesia in pediatrics not only aids the therapeutic procedure but allows the child to experience the procedure as pleasant and relaxed.
Local anesthetics are used for invasive dental procedures like cavity preparations, deep scaling, surgical procedures, or vital pulp therapy.
Anatomic structures in children are naturally smaller than those in an adult. There are three specific anatomic differences to be aware of in children.
The proximity of blood vessels in the maxillary tuberosity area, where infiltrating deeply with the needle may cause damage to the pterygoid venous plexus or posterior superior alveolar artery and resultant hematoma.
The mandibular ramus is shorter and is narrower anteroposteriorly; therefore, for an inferior alveolar nerve block, the extent of infiltration of the needle must be decreased.
The bone is not completely calcified, permitting expatiated diffusion of the local anesthetic agent.
Anesthesia of the mandibular primary molars may usually be achieved by infiltration in children up to the age of 5 years. A few studies
Inferior alveolar block- the patient is requested to open his mouth as wide as possible while the dentist places the ball of the thumb on the coronoid notch of the anterior border of the ramus. The needle is introduced between the internal oblique ridge and the pterygomandibular raphe.
In a young child (4 years old and younger) the foramen is sometimes located below the plane of occlusion.
In children (4 – 10 years old), the foramen is located on the occlusal plane.
As the child matures, it moves to a higher position above the occlusal plane.
The barrel of the syringe covers the primary mandibular molars on the other side of the arch and parallel to the occlusal plane. During this case, a small amount of solution should be injected, and, after a negative aspirate, the needle should advance until bony contact is acquired, very gently and slowly. When the inferior alveolar nerve block did not adequately anesthetize the teeth, long buccal anesthesia is required. This can be achieved by depositing a few drops of the anesthetic into the buccal sulcus just posterior to the molars.
pka-pH incompatibility
Needle jaw size discrepancy
Tissue vector force
Inadequate volume of solution
Anatomical variation
Some of the most recent advances in anaesthetic methods that provide alternative to conventional methods include techniques:
Computer controlled local anesthetic drug delivery system (CCLAD’s)
Jet injectors
EMLA (Eutectic Mixtures of local Anesthesia)
Topical anesthetic patches
Electronic dental anesthesia
Iontophoresis
In 1997 the first computer controlled local anesthetic delivery (CCLAD) system was introduced into dentistry. The Wand (recently renamed: The Wand/Component; Milestone Scientific, Inc., Livingston, NJ) was designed to improve on the ergonomics and precision of the dental syringe. The system enables a dentist or hygienist to accurately manipulate needle placement with fingertip accuracy and deliver the local anesthetic with a foot-activated control. The lightweight hand- piece is held in a pen like grasp that provides increased tactile sensation and control compared with the traditional syringe.
At present, two CCLADs are available:
The Wand handpiece provides increased tactile control and ergonomics. In two clinical trials operators were able to achieve a more comfortable needle puncture for patients when using The Wand handpiece compared with the traditional syringe. This was attributed to the lightweight ergonomically designed handpiece allowing for enhanced tactile sensation.
The hand piece controls are:
The front button with the arrow and square controls the "Start/Stop" functions by initiating or terminating the selected program.
The middle button activates the "Aspiration" function, by slightly retracting the plunger.
The rear button initiates "Double Rate" and operates in the same manner as the Double Rate button on the unit. It doubles the preprogrammed injection rate. Selecting it again resumes the preprogrammed speed.
Standard dental local anesthetic cartridges and dental needles may be used in the CCS.
In 1947, Hingson and Hughes
The use of this instrument has proven to be successful in other areas including insulin delivery, regional and digital blocks, anesthesia for incision of non-dental abscess and aspiration biopsy of lymph nodes and repair of lacerations to the head and extremities and mass immunizations. In all cases, there was a marked preference by patients for the jet injection instrument over more conventional injection procedures.
Clinical dental studies have been performed, in 1991
Jet injection is based on the principle that liquids forced through very small openings, called jets, at very high pressure can penetrate intact skin or mucous membrane
The most commonly used jet injectors in dentistry
Syrijet mark II
Madajet XL
Jet Injector in root canal procedures - removing the distance cone (plastic tip) position the tip of the nozzle over the canal and firing anesthesia directly into the canal. The anesthesia provided by the Jet Injector is most sufficient in the removal of deciduous roots and loose teeth.
Perhaps one of the most important advantages of this instrument is its ability to produce good anesthesia in the palate. By injecting on either side or adjacent to the papillae at the nasopalatine foramen, unusually good anesthesia can be obtained. Since this can be done in almost all cases without pain, the technique deserves the interest of every dentist who must infiltrate this tissue with a needle and syringe.
Eutectic is defined as a mixture of 2 or more compounds with the lowest melting point. EMLA cream (composed of lidocaine 2.5% and prilocaine 2.5%) is an emulsion in which the oil phase is a eutectic mixture of lidocaine and prilocaine in a ratio of 1:1 by weight. It was designed as a topical anesthetic able to provide surface anesthesia of intact skin (other topical anesthetics do not produce a clinical action on intact skin, only abraded skin), and as such is used primarily before painful procedures, such as venipuncture and other needle insertions. Originally marketed for use in pediatrics, EMLA has gained popularity among needle-phobic adults and persons having other superficial, but painful, procedures performed (e.g., hair removal).
The buccal sulcus in relation to the concerned tooth will be wiped free of saliva.
Isolation with cotton rolls and suction tip
About 0.5 gm of EMLA will be taken on a 2”x2” folded gauze piece.
It will be then placed on the buccal gingival nearer the sulcus and kept in position for 10 minutes.
Patients with congenital or idiopathic methemoglobinemia.
Infants under the age of 12 months who are receiving treatment with methemoglobin-inducing agents.
Patients with a known sensitivity to amide-type local anesthetics or any other component of the product.
Anesthetic patches containing lidocaine base that is dispensed through a bio adhesive matrix and applied directly to the oral mucosa recently have been approved by the U.S food and drug administration and are commercially available
Soft tissue procedures
Preinjection procedures
Restorations of primary teeth
Root planning and scaling
Surface or small fillings
Electronic dental anesthesia requires a considerable degree of patient cooperation and participation to be successful. The use of EDA in younger populations, although not contraindicated, requires a more intensive evaluation of patients' abilities to both understand the concept of EDA and their ability to perform their tasks properly. To manage acute pain, higher frequency of electronic stimulation is necessary. The most often used frequency for acute pain management has been 120 Hz, although one EDA unit provided 16,000 Hz.
Two areas in which EDA has been used successfully in dentistry are:
Ineffective local anesthesia
Instances where local anesthetics cannot be administered
Cardiac pacemakers
Neurological disorders
Status post-cerebrovascular accident (stroke)
History of transient ischemic attacks
History of epilepsy
3. Pregnancy
4. Immaturity (inability to understand the concept of patient control of pain
Young pediatric patient
Older patients with senile dementia
Language communication difficulties
Iontophoresis has a wide range of application in dentistry, one of which is to produce a non-invasive technique of anaesthesia. It can be used as a means of delivering local anaesthetics to deeper tissues after topical application. It aids in the penetration of positively charged agents such as lignocaine and adrenaline to tissues under the influence of electrical charge.
Gangarosa described the use of iontophoresis for three basic applications in dentistry
Treatment of hypersensitive dentine (e.g. in teeth sensitive to air and cold liquids) using negatively charged fluoride ions
Treatment of oral ulcers (‘canker sores’) and herpes labialis lesions (‘fever blisters’) using negatively charged corticosteroids and antiviral drugs, respectively.
Topical anesthesia
There is a lack of recent studies regarding the application of iontophoresis in dentistry. A clinical study
Good local analgesia requires highly skilled dental professionals to apply this knowledge coupled with a detailed understanding of the anatomical complexities to provide advanced pain management for the patients. Failure to achieve anesthesia can be a significant problem in the day to day practice of dentistry
The trend is changing as education, research and instrumentation reduce the cognitive and emotional barriers in the dentist’s and child’s perceptions of the local anesthesia experience. Child’s emotions surrounding injections are some of the most powerful feelings that dentists routinely encounter in daily dental practice. Alternative technique can add to the dentist’s skills in treating patients with comfort and efficiency.