1. INTRODUCTION:

Local anaesthesia is most commonly used to achieve pain control in dentistry. The achievement of good local anaesthesia requires knowledge of the agents being used, the neuroanatomy involved, best techniques and devices available. The needle is the most fear producing part of the armamentarium for the delivery of local anaesthetics. Newer technologies have been developed that can assist the dentist in providing enhanced pain relief with reduced injection pain and minimum adverse effects. Recently many innovations have been added to the traditional methods of drug delivery systems. These include,

1. Computer controlled local anaesthetic delivery systems

2. Jet injectors

3.Intra-osseous systems

4. Vibrotactile devices

5. Safety dental syringes

6. Denti-patch

7. Iontophoresis

8. EMLA

9.Electronic Dental Anesthesia (EDA).

Computer-Controlledlocal Anesthetic Delivery Systems [Cclad]

In the mid-1990s, work started on the development of local anaesthetic delivery systems that incorporated computer technology to control the rate of flow of the anaesthetic solution through the needle. This concept is now called computer-controlled local anaesthetic delivery (CCLAD) (1), (2).

In 1997, the first of these CCLAD devices, the WandTM (Milestone Scientific, Inc., Livingston, N.J.), was introduced. The system enabled a dentist or hygienist to accurately manipulate needle placement with fingertip accuracy and deliver the LA with a foot-activated control. The lightweight hand piece is held in a pengrasp that provides the user with greater tactile sensation and control compared to a traditional syringe. The available flow rates of LA delivery are controlled by a computer and thus remain consistent from one injection to the next. Dr. Mark Hochman and coworkers were the first to demonstrate a marked reduction in pain perception for injections using a CCLAD system (3).Several CCLAD systems are available, including the Wand/Com- puDentTM system, Comfort Control SyringeTM, Quick Sleeper TM and Anaeject TM.

Comfort Control Syringe:

Dentsply International, N. York, USA was marketed as an alternative to the Wand and has two components; base unit and syringe and there is no foot pedal. The most important function of this unit is injection and aspiration can be controlled directly from the syringe (4).There are five different basic injection (Nerve block, infiltration, PDL, IO and Palatal regions) rate settings for specific applications. Computerized delivery of local anaesthesia for palatal infiltrations has been found to result in low levels of stress and a low pain reaction comparing to conventional method(5).

Single-Tooth Anaesthesia [STA]

The manufacturers of the original CCLAD, the Wand, introduced a new device, Single Tooth Anaesthesia (STATM) in 2006. This incorporates dynamic pressure-sensing (DPS) technology that provides a constant monitoring of the exit pressure of the local anaesthetic solution in real time during all phases of the drug’s administration

Computer-Controlled Local Nesthetic Delivery Systems [C Clad]

In 1997, the first of these CCLAD devices, the WandTM (Milestone Scientific, Inc., Livingston, N.J.), was introduced. The system enabled a dentist or hygienist to accurately manipulate needle placement with fingertip accuracy and deliver the LA with a foot-activated control. The lightweight hand piece is held in a pengrasp that provides the user with greater tactile sensation and control compared to a traditional syringe. The available flow rates of LA delivery are controlled by a computer and thus remain consistent from one injection to the next.Dr. Mark Hochman and coworkers were the first to demonstrate a marked reduction in pain perception for injections using a CCLAD system(3).Several CCLAD systems are available, including the Wand/Com- puDentTM system, Comfort Control SyringeTM, QuickSleeperTM and AnaejectTM.

Comfort Control Syringe:

Dentsply International, N. York, USA was marketed as an alternative to the Wand and has two components; base unit and syringe and there is no foot pedal. The most important function of this unit is injection and aspiration can be controlled directly from the syringe(4).There are five different basic injection (Nerve block, infiltration, PDL, IO and Palatal regions) rate settings for specific applications. Computerized delivery of local anaesthesia for palatal infiltrations has been found to result in low levels of stress and a low pain reaction comparing to conventional method (5).

Single-Tooth Anaesthesia [STA]

The STA-System is composed of a lightweight, portable drive unit and a separate single-use disposable handpiece assembly attachment (STA-Wand). The drive unit is powered by a standard AC electrical connection. The handpiece consists of a handle, microbore tubing, and an anaesthetic cartridge holder that accepts any standard dental anaesthetic cartridge and any standard medical needle (7).

New Injection Techniques:

a. Anterior middle superior alveolar and palatal approach-anterior superior alveolar nerve block:

CCLAD has made both techniques quite popular, as the level of patient discomfort is minimal.The AMSA nerve block provides pulpal anaesthesia to the maxillary incisors, canines and premolars on the side of injection (8).The palatal approach-anterior superior alveolar nerve block provides pulpal anaesthesia to the six anterior teeth - canine to canine bilaterally, as well as the palatal and labial gingiva and mucoperiosteum and bone overlying these teeth.(9)

b. Periodontal ligament injection: Another injection technique, the periodontal ligament injection, also known as the intraligamentary injection (ILI) has been extremely useful when anesthesia of a single tooth in the mandible is required.(10)

2. Jet Injectors:

This devices have been developed that would eliminate the need to inject material by needle and syringe. 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.ex., are Injex, Syrijet, Mark II and MED-JET H III. In MED-JET H III. (11)

3. Intra-Osseous Anesthesia Systems [I O] Systems

Aim of intra-osseous anaesthesia is to inject local anaesthesia solution into cancellous bone adjacent to the apex of the tooth by piercing buccal gingiva and bone in relation to the tooth to be anesthetized.(12)

These systems are: Stabident (Fairfax Dental, Miami, Florida), X-tip (Dentsply International Inc, Tulsa, OK, USA), and IntraFlow (Pro-Dex Incorporated, Santa Ana, CA, USA).

a. Stabident:

Advantages:

It is relatively inexpensive and can be used with equipment already existing in a dental office: A slow-speed hand piece with a latch contra-angle for the perforator and a standard dental anaesthetic syringe for the needle.

Disadvantages:

It can be used only in visible and readily accessible area because while giving intraoral injection once the perforator is withdrawn, it can be extremely difficult to locate the perforation site with the anaesthetic needle.

b. X-Tip:

The X-Tip solves location of perforation site problem by making the pilot drill itself a hollow tube through which a 27-gauge needle can pass. The initial drillstays in place, allowing the anaesthetic to be placed without hunting for the hole that was just created.

c. IntraFlow:

The IntraFlow device(Pro-Dex Medical Devices, Irvine, CA, USA)is essentially a dental handpiece equipped with an injection system built into the body.(13)

Advantages: the IntraFlowanaesthesia system is that it allows entry into the penetration zone, injection, and withdrawal in one continuous step, without the need to relocate the perforation site. This single-step method can be helpful in penetration zones.

Disadvantages: the IntraFlow are start-up and maintenance costs, and that the device can occasionally leak anaesthetic, especially if not assembled properly.(14)

4. Vibrotactile Devices:

These devices work on the principle of ‘gate control’ theory which suggests that pain can be reduced by simultaneous activation of nerve fibers through the use of vibration. The devices are: VibraJect, Dental Vibe, Accupal.

a.Vibra Ject:

It is a small battery-operated attachment that snaps on to the standard dental syringe. It produces a high-frequency vibration to the needle that is strong enough for the patient to feel. This device is combination with an electrical injection device(15),(16).

b. Dental Vibe:

Dental Vibe is a cordless hand held device which gently stimulates the sensory receptors at the injection site causing the neural pain gate to close.

Advantages: The tissues are vibrated before the needle penetrates.

Disadvantages: It is not directly attached to the syringe and a separate unit is required, so both hands are engaged.

c. Accupal:

The Accupal (Hot Springs, AR, USA) is a cordless device that uses both vibration and pressure to precondition the oral mucosa.

5. Safety Dental Syringes:

Use of a safety syringe minimizes the risk of accidental needle-stick injury occurring to a dental health provider with a contaminated needle after the administration of LA. These syringes hold a sheath that ‘locks’ over the needle when it is removed from the patient's tissues preventing accidental needle stick(17).

The examples are:

a. Ultra safe syringe:

The UltraSafe syringe (Safety Syringes Inc, Carlsbad, CA, USA) is a disposable syringe and needle with a transparent, plastic syringe barrel, which has a retractable needle sheath. The UltraSafe syringe the entire assembly is disposable and is not autoclavable.

b. Ultra safety plus XL syringe:

The Ultra Safety Plus XL syringe (Septodont, Lancaster, PA, USA) has a sterile disposable protective shield that is fitted with a dental needle into which anestheticcarpules are placed. The plunger assembly is reusable and autoclavable. (18)

c. Hyposafety Syringe:

The HypoSafety syringe (Dentsply MPL Technologies, Susquehanna, PA, USA) is a translucent disposable plastic syringe and needle combination. The needle can be retracted into the barrel of the syringe after the injection.

d. Safety Wand:

theSafetyWand has been developed for use with the CompuDent system. The safety system has a pen-like grasp that allows maximum tactile control and an auto-retracting design that shields the needle when not in use.

e. Rev Vac Safety Syringe:

The RevVac safety syringe operates the same as a standard conventional syringe. The syringe cannot be reused.

6. Dentipatch [Intraoral Lignocaine Patch]:

The DentiPatch® system is applied to the buccal mucosa and it releases Lidocaine to provide topical anaesthesia. By inhibiting the ionic fluxes required for the initiation and conduction of impulses, Lidocaine stabilizes the neuronal membrane, therefore effecting local anaesthetic action. It contains 10-20% of Lidocaine and must be placed on the dried mucosa for a minimum of 15 minutes to achieve the required action. It is useful in reducing the pain associated with injections of local anaesthetic into the gingival for both maxilla and mandible.(19)

7. Iontophoresis:

It is a painless modality of administrating anaesthesia. It is a form of active transportation by extending its sensory component. It delivers the drug into the skin by using a constant low-voltage direct current, promoting ion transport through the skin. The positively charged lignocaine molecules are delivered when placed under a positive electrode for local anaesthesia.(20)

8. Emla

In recent years, a new topical anaesthetic agent has been developed, EMLA cream 5% (eutectic mixture of local anaesthetics, Astra Pharmaceuticals, Sydney, Australia). The cream is a 1: 1 oil/water emulsion of a eutectic mixture of lidocaine (2.5%) and prilocaine (2.5%) bases. The eutectic mixture has a lower melting point (17°C) compared with the respective individual melting points of the lidocaine base (66-690C) and the prilocaine base (36-380C). This new physical property allows the lidocaine/prilocaine eutectic mixture to be liquid at mouth temperature and thus facilitate rapid absorption of the bases. It has become the treatment of choice when patients desire a needle-free method for topical anesthesia. (21)

9. Electronic Dental Anesthesia (EDA):

This technique involves the use of the principle of Transcutaneous Electrical Nerve Stimulation (TENS). It is a non- invasive, low-risk nerve stimulation to relieve the pain. By using electric current produced by a device to stimulate the nerves, it can be used as a supplement to conventional local anaesthesia.(22)

CONCLUSIONS:

Local anaesthesia has been the cornerstone of modern day pain-free dental practice. Many newer delivery methods have been discovered and introduced to enhance a better quality performance during dental treatment. The dental practitioners must be well aware of their usage and application so as to provide the benefits of latest technology to their patients and also to reduce the public fear of seeking dental treatment.

REFERENCES:

1. Nicholson JW, Berry TG, Summitt JB, Yuan CH, Witten TM. Pain perception and utility: A comparison of the syringe and computerized local injection techniques. Gen Dent 2001;49:167‐72.

2. Proceedings of the 1st Annual Computer-Controlled Local Anaesthesia Delivery (C-CLAD) System meeting. Introductory remarks. New Orleans, La., Feb 2008.

3. Hochman MN, Chiarello D, Hochman CB, Lopatkin R, Pergola S. Computerized Local Anesthesia Delivery vs. Traditional Syringe Technique. NY State Dent J. 1997 ;63 :24-9.

4. Lackey AD. New horizons in local anesthesia. Dent Today 1998; 17(8): 78-79.

5. Perry DA, Loomer PM. Maximizing Pain Control. The AMSA Injection can provide anaesthesia with few injections and less pain. Dimens Dent Hyg 2003;1:28‐33.

6. Hochman M. Inventor: Pressure/force computer controlled drug delivery system and the like. Assigned: Milestone Scientific, Inc. US Patent 6,200,289. March 2001

7. Ferrari M, Cagidiaco MC, Vichi A, Goracci C. Efficacy of the Computer-Controlled Injection System STA, and the dental syringe for intraligamentary anaesthesia in restorative patients. Inter Dent SA. 2008;11(1):4-12.

8. Malamed SF. Techniques of Maxillary Anesthesia. In: Malamed SF, editor. Handbook of Local Anaesthesia. 6th ed. St. Louis: CV Mosby; 2004. pp. 213–7.

9. Friedman MJ, Hochman MN. Using AMSA and P-ASA nerve blocks for esthetic restorative dentistry. Gen Dent. 2001 ; 49:506–11.

10. Malamed SF. The periodontal ligament (PDL) injection: An alternative to inferior alveolar nerve block. Oral Surg Oral Med Oral Pathol. 1982;53:117–21.

11. Dabarakis NN, Alexander V, Tsirlis AT, Parissis NA, and Nikolaos M. Needle-less local anaesthesia: clinical evaluation of the effectiveness of the jet anaesthesia Injex in local anaesthesia in dentistry. Quintessence Int. 2007 Nov-Dec;38(10):E572-6.

12. Langthasa M, Yeluri R, Jain AA, Munshi AK. Comparison of the pain perception in children using comfort control syringe and a conventional injection technique during pediatric dental procedures.J Indian SocPedodPrev Dent 2012;30(4): 323-328.

13. Remmers T, Glickman G, Spears R, He J. The efficacy of IntraFlowintraosseous injection as a primary anaesthesia technique. J Endod 2008;34:280‐3.

14. Ogle OE, Mahjoubi G. Advances in local anaesthesia in dentistry. Dent Clin North Am. 2011;55:481–99.

15. Saijo M, Ito E, Ichinohe T, Kaneko Y. Lack of pain reduction by a vibrating local anaesthetic attachment: A pilot study. AnesthProg. 2005;52:62–4.

16. Nanitsos E, Vartuli R, Forte A, Dennison PJ, Peck CC: The effect of vibration on pain during local anaesthesia injections. Aust Dent J 2010, 54:94-100.

17. Malamed SF. 5th ed. St Louis: Mosby-Year Book; 2004. Handbook of Local Anaesthesia.

18. Ogle OE, Mahjoubi G. Advances in local anaesthesia in dentistry. Dent Clin North Am. 2011;55:481–99.

19. Leopold A, Wilson S, Weaver JS, Moursi AM. Pharmacokinetics of lidocaine delivered from a transmucosal patch in children. AnesthProg 2002; 49(3) :82-7.

20. Arapostathis KN, Dabarakis NN, Coolidge T, Tsirlis A, Kotsanos N. Comparison of acceptance, preference, and efficacy between jet injection INJEX and local infiltration anesthesia in 6 to 11 year old dental patients. Anesth Prog.2010; 57(1) :3-12.

21. Riendeau LA, Bennett D, Black-Noller G, Fan L, Scavone JM. Evaluation of the analgesic efficacy of EMLA cream in volunteers with differing skin pigmentation undergoing venipuncture. RegAnaesth Pain Med 1999; 24(2): 165-169.

22. 22Malamed SF, Quinn CL, Torgersen RT, ThompsonW. Electronic dental anesthesia for restorativedentistry. AnesthProg. 1989 ; 36:195-7.

Received on 04.05.2016 Modified on 24.05.2016

Research J. Pharm. and Tech 2016; 9(10):1761-1764.

DOI: 10.5958/0974-360X.2016.00354.1