RECENT ADVANCES IN LOCAL ANESTHESIA

PRESENTER Nitesh chaurasia Papular chaudhary

CONTENTS Introduction Newer LA Drugs LA Delivery Systems CCLAD system Jet injectors Safety dental syringe Devices for intra-osseous anesthesia

Vibrotactile devices Intra nasal anesthetic

INTRODUCTION

The most important skill required of all dental practitioners is the ability to provide safe and effective local anesthesia

Most of the researches are focused on improvement in the area of anesthetic agents, delivery devices and technique involved.

Newer technologies have been developed that can assist the dentist in providing enhanced pain relief with reduced injection pain and fewer adverse effects

Newer drugs Lignocaine Hydrochloride is considered the “Gold Standard‟ among LA.

Two relatively new drugs that have proved to be equally or more efficient to Lignocaine are

1. Articaine 2. Centbucridine

Articaine It belongs to the Amide group of local anesthetics.

It consists of a thiophene ring instead of a benzene ring and an ester group that is metabolized by esterases in the tissues.

Elimination of Articaine is exponential with a half-life of about 27 minutes.

Metabolism is mainly in the liver and plasma

5-10% secreted unchanged and 90% is metabolized.

Articaine vs. Lignocaine: 1. Articaine has a faster onset of action 2. Articaine has a longer duration of action

3. Articaine has a higher success rate 4. Articaine has a greater potency (1.5 times more potent)

5. Systemic intoxication of Articaine is lower

6. Articaine is a very safe drug

Continue.. The thiophene ring bestows enhanced performance by increasing the lipid solubility and protein binding capacity of the drug

Lipid solubility and protein binding properties are intrinsic qualities of a local anesthetic drug molecule

enhanced diffusion into soft and hard tissues than other local anesthetics

Continue.. Articaine has a smaller pK value 1.7 times greater volume needed for lignocaine 2% to that of 4% Articaine for achieving the same anesthesia

One study revealed that 4% Articaine with 1:1,00,000 epinephrine was the most effective solution

Articaine buccal infiltration enhances the effectiveness of lidocaine IANB

Other properties of Articaine

Pka- 7.8 PH of vasoconstrictor- containing solution is 3.5 -4

Onset of action: 1-2 min for infiltration and 2-2.5 for mandibular block(for 1:100000)

Effective dental concentration: 4%with 1;100000 or 1:200000

MRD:7.2mg/kg with no absolute maximum Duration of action:60-75 min of pulpal anesthesia for 1:100000

Documented Adverse effect: methemoglobinemia, paresthesia

Ocular complications have been reported for infra-orbital nerve block. This may be due to the increased diffusion of drug through the tissues including bone

Not recommended in children below 4 year and lactating mother

Pregnancy falls under class C

Centbucridine synthesized at the Centre for Drug Research of India at Lucknow, India in the year 1983

A quinolone derivative with local anesthetic action .

It has intrinsic vasoconstricting and anti-histaminic properties.

Concentration of 0.5% can be used effectively for infiltration, nerve blocks and spinal anesthesia.

Randomized study result compared the efficacy and tolerability of 0.5% Centbucridine with 2% lignocaine for dental extractions

the results revealed that the dose of analgesia obtained with Centbucridine compared well with that of lignocaine

it was well tolerated without any serious side-effects or significant changes in the cardio-vascular parameters

Lignocaine vs centbucridine

Anesthetic potency 4-5 times greater than that of 2% lignocaine.

Onset of action is quicker and duration is longer

It doesnot require simultaneous administration of adrenaline

It doesnot effect the CVS parameter due to its moderate antihistaminic activity and is not likely to show skin sensitivity.

Can be used in patient hypersensitive to lignocaine.

Centbucridine has been tested successfully as a topical anesthetic in ophthalmic surgeries.

Its topical anesthetic action is concentration dependent.

Its use in dentistry is still a matter of study

Phentolamine(OraVerse) an indication for the reversal of soft tissue anesthesia (lip & tongue numbness).

Phentolamine Mesylate is a non-selective alpha adrenergic blocking agent and reverses the effects of epinephrine and nor-epinephrine on tissues

Medical uses:diagnosis of pheochromocytoma, tt of HTN in pheochromocytoma and prevention of tissue necrosis after norepinephrine extravasation.

The ultimate effect of alpha receptor blockade is vaso-dilatation.

Peak concentration is achieved after 20 minutes and the elimination half-life is 2-3 hours.

Availabe injectable dose 0.4mg/1.7ml(max. 0.8mg)

Dose based on amount of local anesthetic administred

½ cartridge of LA :1/2 cartridge of phentolamine (0.2mg)

Candidates for phentolamine reversal are:

1.Conservative dentistry2.Nonsurgical periodontics3.Pediatric dentistry4.Medically compromised patient5.Special need patient and post mandibular implant

Adverse reactions such as diarrhea, facial swelling, hypertension, jaw pain, oral pain, injection site reactions, tenderness and vomiting have been reported.

Majority of the adverse reactions are resolved within 48 hours.

Administration with caution in patients with cardiovascular disease and stroke.

Is not recommended in children younger than 6 years of age and weighing less than 15 kg

Buffered local anesthetics

Standard Local anesthetic solution are buffered few mins before injection with sodium bicarbonate

PH of buffered dental cartridge of LA ranges between 7.35 -7.5( i.e.closer to physiologic range)

Well known and accepted in medicine but prefilled LA cartridge in dentistry has limited its use

Advantages Elliminates the sting on injection( greater patient comfort during inection)

More rapid onset of action(2 min) Reduces tissue and post injection soreness

Introduces the independent anesthetic action of CO2

Introduces catalytic effect of CO2

Action of CO2 Direct depressant effect on axon Concentrating the local anesthetic inside the nerve trunk though ion trapping

Changing the charge of local anesthetic inside the nerve axon

EMLA – Eutectic Mixture of Local Anesthetics

Used as topical anesthetic able to provide surface anesthesia for intact skin

Composed of lidocaine 2.5% and prilocaine 2.5%

Supplied as a 5g or 30g tube or as an EMLA anesthetic disc.

EMLA anesthetic disc is packaged in protective laminate foil surrounded by adhesive tape.

Indication As topical anesthetic in pediatric patient and needle phobic patient

Venipuncture Circumcision and gynecologic procedure

During leg ulcer debridementNote: should be applied 1 hr before the procedure.

Contraindicated Patient with congenital or idiopathic methemoglobinemia

Infants younger than 12 month who are receiving treatment with methemoglobine inducing agent

Known sensitivity to amide type LA

Lidocaine and prilocaine periodontal gel (Oraqix)

Lidocaine and prilocaine periodontal gel 2.5%/2.5%(Oraqix)

Eutectic mixture of local anesthetics

Solution at room temperature; gel at body temperature

First topical anesthetic specifically designed for scaling and root planing

Oraqix delivery syringe

Oraqix cartridge contents Lidocaine/prilocaine 2.5%/2.5% Poloxamers 188 and 407 HCl for pH adjustment Purified water pH 7.5-8.0

Newer Drug delivery system for dental LA

Electronic Dental Anesthesia

Principle of Transcutaneous Electrical Nerve Stimulation (TENS) which has been used for the relief of pain.

Some limitations are increased salivary flow and inability to use metal instruments freely.

It is powered by a battery ,two small sponges are placed in the patients mouth or on the face, which are attached to the control box that the patient uses to select the depth of anesthesia

Indication Patient having needle phobia Ineffective LA Instances where LA cannot be administered

TMJ(chronic pain) Nonsurgical periodontal pain Restorative dentistry Fixed prosthodontic procedure Reversal of soft tissue anesthesia

Advantages No need of needle No need for injections of drugs Patient is in control of the anesthesia

No residual anesthetic effect at the end of procedure

Residual analgesic effect remains for several hours

Disadvantages Cost of the unit Training ‘Learning curve‘ initial success may be low but increases with experience

Intraoral electrode:weak link in the entire system

It is contraindicated in several conditions such as

heart disease,seizures, neurological disorders, brain tumors,patients wearing pacemakers and cochlear implants

Dentipatch a patch that contains 10-20% lidocaine is placed on the dried mucosa for 15 minutes.

Hersh et al (1996) studied the efficacy of this patch and recommended it for use in achieving topical anesthesia for both maxilla and mandible.

Jet Injection Jet-injection technology is based on the principle of using a mechanical energy source to create a release of pressure sufficient to push a dose of liquid medication through a very small orifice.

creating a thin column of fluid with enough force that it can penetrate soft tissue into the subcutaneous tissue without a needle

advantages over traditional needle injectors by

being fast and easy to use, with little or no pain, less tissue damage, and faster drug absorption at the injection site

This technique is particularly effective for palatal injections

Marketed as Syrijet and MED-JET H III

Iontophoresis Iontophoresis is non-invasive transdermal drug delivery

This technique is a suitable alternative for application of drug in achieving surface anesthesia.

It is a painless modality of administrating anesthesia.

a fast and effective way to apply a local anesthetic without needles or pain. The method is faster and penetrates deeper than topical anesthetic creams and is an ideal alternative for numbing the skin before injections and biopsies.

After just 10 minutes, the skin is as numb as after 60 minutes of traditional treatment with creams.

We recommend a Xylocaine topical anesthetic solution, 40 mg/ml.

Xylocaine has a positive charge, so connect the anode (red clamp) to the drug delivery electrode

CCLAD Systems (Computer Controlled Local Anesthesia Delivery System)

Introduced the first CCLAD system in 1997 and was termed the “WAND” and the subsequent versions were renamed as “WAND PLUS” and“COMPUDENT”.

In 2001, DENTSPLY International introduced the

“Comfort Control Syringe – CCS” and similar devices originating outside USA were; “Quick Sleeper, Sleeper

One from France, “Anaeject” and “Orastar” from Japan.

Wand” has 3 components: Base unit, Foot pedal and Disposable Handpiece assembly

Base unit consists of a microprocessor and connects to the foot pedal and Handpiece assembly that accepts the LA cartridge.

LA solution from the cartridge passes through the microbore tubing in the Handpiece assembly and needle into the target tissue

Rate of Injection: foot pedal controls the rate of injection and if aspiration feature is enabled, it prevents inadvertent intravascular injections.

1. Slow: 0.005ml/s – needle insertion, PDL injection, Palatal administration

2. Fast: 0.03ml/s – buccal infiltrations, nerve block

3. Turbo: 0.06ml/s

“Single Tooth Anesthesia System – STA System” was introduced by Milestone Scientific in 2007.

Its advantages include „Dynamic Pressure Sensing – DPS‟

which provides continuous feedback to the user aboutthe pressure at the needle tip to identify the ideal needle placement for PDL injections.

Rate of Injection: 3 modes to control the rate of injection

1. STA mode: Single, slow rate of injection 2. Normal mode: emulates the Compudent device 3. Turbo mode: faster rate of injection – 0.06ml/s

Comfort Control Syringes consists of two components; base unit and syringe. The most important functions of the unit (injection and aspiration) can be controlled directly from the syringe.

Rate of injection: Five different basic injection rate settings for specific applications: block, infiltration,PDL, IO and Palatal regions.

The unit uses two stage delivery rates for every injection.

It initially expresses the LA solution at an extremely low rate and after 10 seconds the rate slowly increases to the pre-programed value for the selected injection technique.

Advantages of CCLADs1) Ability to administer small quantities of LA solution continuously during needle insertion, which anesthetizes the tissue immediately ahead of the advancing needle.2) Steady infusion of the anesthetic solution at the target site reduces the discomfort associated with less controlled injections.3) More accurate needle insertion4) Less pain on injection5) Less fear of injection6) More controlled insertion of the needle

7) Ability to rotate the Handpiece back and forth during needle insertion to avoid needle deflections & reduced

force for insertion leading to more comfort for patients.

8) Ability to perform newer techniques such as a. AMSA – anterior middle superior alveolar block

b. PDL – periodontal ligament infiltration c. P-ASA – palatal approach to anterior superior alveolar block.

Because of these attributes the CCLAD devices are better tolerated by patients and produce less disruptive behavior can be used successfully for

restorations, pulpal therapies & extractions in pediatric dentistry

Intra-Osseous Anesthesia The use of motor driven perforator to penetrate the buccal gingiva and bone can be considered as the first modern technique of IO anesthesia.

The devices used for this technique, inject the solution into the cancellous bone adjacent to the root apex. Commonly used devices are:

i. Stabidentii. X – Tipiii. Intraflow

(i)Stabident: It includes a solid 27 gauge perforator needle with a beveled tip and a plastic base which fits a latch type slow speed contra-angle handpiece.

This perforator creates a small tunnel through attached gingiva,periosteum and alveolar bone.

The insertion point of the perforator is in the attached gingiva, 2mm below the facial gingival margin and midway between the tooth of intent and immediately adjacent (distal) tooth.

The angle of perforation is usually directed apically in the mandibular incisor region whereas a more perpendicular angle is advantageous in the molar region to avoid bending the perforator against the dense cortical bone.

Later a 27 gauge ultra-short needle is used to deposit the local anesthetic solution

(ii)X-tip X – Tip: this system consists of three parts; the drill,perforator, 25 gauge guide sleeve

The advantage of this system over Stabident the ease with which the perforation could be located for inserting the needle.

The drill leads the guide sleeve through the cortical plate into the cancellous bone.

The drill portion is removed, leaving the guide sleeve in place, which directs the needle into the cancellous bone to deposit the LA solution. Later the guide sleeve is removed with a hemostat

(iii)Intraflow the Intraflow HTP Anesthesia Delivery System is an “all in one” system that allows the operator to perforate the bone and deposit the anesthetic solution in a single step.

The device is a dental handpiece equipped with an injection system built into its body. A 24 gauge hollow perforator is used to penetrate the bone and infuse the LA solution.

The anesthetic solution from the cartridge is routed to the perforator by a disposable transfuser that also serves to cover the switch used to select between the perforator rotation and anesthetic infusion modes.

Penetration with this low speed high torque device is by a single, steady insertion using direct pressure

Vibrotactile devices aimed at easing the fear of the needle take advantage of the gate control theory of pain management, which suggests that pain can be reduced by simultaneous activation of nerve fibers through the use of vibration

Devices are :vibrajet,dentvibe and accupal

VibraJet It is a small battery-operated attachment that snaps on to the standard dental syringe. It delivers a high-frequency vibration to the needle that is strong enough for the patient to feel.

DentalVibe It is a cordless, rechargeable, hand held device that delivers soothing, pulsed, percussive micro-oscillations to the site where an injection is being administered.

Its U-shaped vibrating tip attached to a microprocessor-controlled Vibra-Pulse motor gently stimulates the sensory receptors at the injection site, effectively closing the neural pain gate, blocking the painful sensation of injections.

It also lights the injection area and has an attachment to retract the lip or cheek

Accupal A cordless device that uses both vibration and pressure to precondition the oral mucosa.

Accupal provides pressure and vibrates the injection site 360° proximal to the needle penetration, which shuts the “pain gate,” according to the manufacturer.

applying moderate pressure, the unit light up the area and begins to vibrate. The needle is placed through a hole in the head of the disposable tip, which is attached to the motor.

Intranasal LA The absorption of drugs through the nasal mucosa to achieve a systemic effect has long and varied history

The nares are extremely vascular so most drugs instilled into them will be absorbed rapidly and distributed systematically

Snorting line of cocaine is an example of illicit use of this route of drug administrations

Critical care medicine has used intranasal drug administration of the central nervous system depressant drug midazolam in the management of status epilepticus in young children

Midazolam(0.2mg/kg)and diazepam(0.3 mg /kg)

UsesEar, nose and throat surgical proceduresTetracaine,an ester type local anesthetic ,is commonly used to provide a numbing effect before surgical manipulations in the noseFor dental ,vasoconstritor oxymetazoline is added to the teracaine to enhance effecticveness.

references Hand book of local anesthesia by Stanley F. Malamed

IOSR Journal of Dental and Medical Sciences (JDMS)

www.iosrjournals.org www.ncbi.nlm.nih.gov/pmc/articles/PMC3800379/