Fundamentals of technique Types of local anaesthesia Topical or surface anaesthesia

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1 Fundamentals of technique The importance of a quiet, confident, and friendly manner towards all patients so physical comfort is also essential for the co-operation of the patient and the ease of operation of the dental surgeon. The patient should be seated in a semi-reclining position with the back and legs supported and with head rest in the nape of the neck. Most adult patients will respond to the dental surgeon's endeavors to gain the patient his or her confidence and so premedication will not be required for the administration of a local anaesthetic for a relatively simple procedure. Types of local anaesthesia For descriptive purposes it is convenient to sub-divide local anaesthesia on an anatomical basis into topical, infiltration, and regional techniques. Topical or surface anaesthesia: is obtained by the application of a suitable anaesthetic agents to an area of either skin or mucous membrane which it penetrates to anaesthetize superficial nerve-ending. It is most commonly used to obtain anaesthesia of mucosa prior to injection. Spray: containing an appropriate local anaesthetic agent are particularly suitable for this purpose because of their rapidity of action. The active ingredient is 10% lignocaine hydrochloride. When used as a spray it is very easy to spread the solution, and its effect, much more extensively than is desired. The onset time of anaesthesia is about 1 minute and the duration round about 10 minute. Ethyl chloride: when sprayed on skin or mucosa volatilizes to rapidly produces anaesthesia by refrigeration. This phenomenon is of clinical value only when spray directed at a limited area until snow appears.\this technique is of limited value is occasionally used to produce surface anaesthesia prior to incision of a fluctuant abscesses. Fig. 1 Fig. 1 1

2 Ointment: containing 5% lidocaine hydrochloride can be used for a similar purpose but take 3-4 minutes to produce surface anaesthesia. Amethocaine and benzocaine are included in ointments are particularly useful when applied to tender gingivae prior to deep scaling. An emulsion: containing 2% lignocaine hydrochloride is also available. It is useful when taken an impression and following a gingivectomy. One teaspoonful should be used round the mouth and oro-pharynx for 1-2 minute and any excess spat out immediately and is quite safe if swallowed. Jet injection : is a technique in which a small amount of local anaesthetic solution is propelled as a jet into the sub-mucosa without the use of a needle. Fig. 2 Fig. 2 Infiltration anaesthesia Anaesthetic solution deposited near the terminal fibers of any nerve will infiltrate through the tissue to reach the nerve fibers and thus produce anaesthesia of a localized area served by them. Fig. 3 Fig. 3 2

3 This infiltration technique is subdivided into: A. Sub-mucous injection: in this technique the solution is deposited just beneath the mucous membrane. Whilst this is unlikely to produce anaesthesia of the dental pulp it is often employed either to anaesthetize the long buccal nerve prior to the extraction of teeth or for soft tissue surgery. B. Supra-periosteal injection: in some sites, such as the alveolar processes of maxilla the outer cortical plate is thin and perforated by tiny vascular canals as cancellous bone. In these areas when anaesthetic solution is deposited outside the periosteum, it will infiltrate through the periosteum, cortical plate, and medullary bone to the nerve fibers. By this means anaesthesia of the dental pulp can be obtained by injecting along side the approximate position of the tooth apex. The supra-periosteal injection is the technique most frequently used in dentistry. Fig. 4 Fig. 4 C. Sub-periosteal injection: In this technique the anaesthetic solution is deposited between injection is painful. D. Intra-osseous injection: in this technique the solution is deposited within the medullary bone. The procedure is carried out by the use of bone drills and needles especially designed. After giving the ordinary way anaesthesia a very small incision is made through the muco-periosteum at the chosen site of injection to provide access for the introduction of a bur or fine reamer. A small hole is made through the outer cortical plate of bone. It must be near the apex of the tooth concerned without damage to the root of the tooth. Fig. 5 3

4 Fig. 5 E. Intra-septal injection: This modified version of the intra-osseous technique is sometime when difficulty in gaining complete anaesthesia, or when an immediate denture is to be fitted and supra-periosteal techniques are best avoided. Fig. 6 Fig. 6 Regional (block) anaesthesia Anaesthetic solution deposited near a nerve trunk will, by blocking all impulses, produce anaesthesia of the area supplied by that nerve. Although this technique may be used in maxilla and mandible. The used of infiltration technique in mandible is unreliable due to the density of the outer cortical plate of bone. By placing the anaesthetic solution in the pterygomandibular space near the mandibular foramen, regional anaesthesia over the whole distribution of the inferior alveolar nerve on that side is obtained. Fig. 7 4

5 Fig. 7 Periodontal ligament technique Nerve anaesthetized terminal nerve endings at the site of injection at the apex of the tooth. The bone, mucosa, apical, and pulpal tissue in the area of injection. Indication: 1. Pulpal anaesthesia of 1-2 teeth. 2. Situation in which regional block are contraindicated. 3. Aid in the diagnosis of pulpal discomfort. 4. As an adjunctive technique following nerve block if partial anaesthesia is present. Contraindication: 1. Infection or acute inflammation in the area of injection. 2. Patient who requires sensation for psychological comfort. Advantages: 1. Avoid anaesthesia of lip tongue and other soft tissues. 2. Minimum dose of local anaesthesia is required. 3. Rapid onset of profound pulpal and soft tissue anaesthesia. 4. Less traumatic than conventional block technique. Disadvantages: 1. Excessive pressure or rapid injection may break the glass cartridge. 2. A special syringe may be required. 3. Excessive pressure can produce focal Technique: 1. A 27 gauge short needle recommended. 2. Area of insertion: the long axis of the tooth to be treated on its mesial or distal of the root. 3. Target area: is the depth of gingival sulcus. 5

6 Intrapulpal injection This technique is used when pain control is required for pulp extirpation in the absence of adequate anaesthesia from other techniques. Techniques of maxillary anaesthesia The oral cavity is one of the most sensitive parts of the body. Sensory nerve-endings are present in the dental pulp, the periodontal ligament, the alveolar bone, the muco-periosteum, and the mucous membrane. There are several methods of obtaining local anaesthesia. The type of local anesthesia and the dose is depended on two factors are the site of deposition of the drug and the operative intervention, so all type of topical anaesthesia, all type of infiltration injection, infra-orbital nerve block injection, posterior superior alveolar nerve block injection, periodontal ligament injection, and rarely used anterior superior and middle superior alveolar nerve block injection. The maxilla can be divided to three area anterior, middle and posterior area. Fig. 8 Fig. 8 Anaesthesia of the permanent anterior teeth The central, lateral incisor, and canine teeth are innervated by the anterior superior alveolar nerve. These teeth may be anaesthetized together with their supporting tissues and mucoperiosteum by infiltration injection by depositing about 1ml. of local anaesthetic solution near the apex of tooth concerned. The ease with which the floor of the nose may be penetrated due to miscalculation of the length of the root or the depth of the labial sulcus. Fig.9 6

7 Fig. 9 The infra-orbital block injection: since infiltration injections are so effective in the maxilla, block injection is seldom required. However, the infra-orbital block injection may be of value if numerous extractions or extensive surgery are to be undertaken in the anterior teeth regions. It may also be employed for anaesthetizing an anterior teeth where the used of infiltration injections are precluded by the presence of infection at the site of injection. This technique is based upon the fact that solution deposited at the orifice of the infra-orbital foramen pass along the canal to involve both the anterior and middle superior alveolar nerves thus producing anaesthesia of the incisor, canine, and premolar teeth and their supporting structures. Either an intraoral or extraoral approach may be employed for the infra-orbital block. The intraoral technique is more popular and allows the needle to kept out of the patient's sight. Technique: The infra-orbital ridge is palpated and the infra-orbital notch located with the tip of the 1 st finger, which is then moved slightly downwards to lie directly over the infra-orbital foramen. With the finger-tip maintained in that position the thumb reflects the upper lip and expose the site of injection which the tip of long needle is inserted just above the reflection of the mucous membrane over the apex of the 2 nd premolar. The needle is advanced in line with the long axis of the 2 nd premolar to a depth of cm, where the correct position of the tip of the needle overlying the foramen is confirmed when the injection of solution is felt beneath the fingertip. The deposition of 1 ml suffices in most instances. Fig. 10 7

8 Fig10 Anaesthesia of the premolar teeth The mesio-buccal root of the 1 st molar, both premolars, and the buccal supporting tissues and muco-periosteum related to them are innervated via the middle superior alveolar nerve. Infiltration techniques are usually employed to anaesthetize these structures. Deposition of 1 ml of solution suffices to anaesthetize the both premolars teeth but may not be adequate for the 1 st molar because the buccal bone of the zygomatic process is dense and is perforated by comparatively few vascular canals. The density of this bone may impede the penetration of the outer plate by local anaesthetic solution and so it is often necessary to give 2 injection in the more porous sites. Fig Fig11

9 Anaesthesia of molar teeth The 3 rd molar, 2 nd molar, and the disto-buccal and palatal roots of the 1 st molar are innervated by the posterior superior alveolar nerve. Small branches transmit sensation from the buccal supporting tissues in the molar region and the muco-periosteum attached to them. The posterior superior alveolar nerve block when deposit of anaesthetic solution close to the nerve after it leaves its bony canal. Since the introduction of modern local anaesthetic agents it is more usual to employ infiltration injection in these area because the deposition of about 1 ml of solution in the position normally produces adequate anaesthesia without the risk of damage to the pterygoid venous plexus. Technique of posterior superior alveolar nerve block: partially open the mouth, pulling the mandible to the side of injection. Retract the cheek with your finger. Insert the long needle into the height of the muco-buccal fold over the 2 nd molar. Advance the needle slowly in an upward, and backward direction. Deposit ml of solution suffices to block anaesthesia. Infiltration technique: Hold the syringe parallel with the long axis of the tooth. Insert the needle into the height of the muco-buccal fold over target tooth. Advance the needle for a few mm. Deposit slowly about 0.6 ml. Fig. 12 Fig12 Anaesthesia of the palatal tissues Nerve ending in the muco-periosteum related to the anterior maxillary teeth and premaxilla transmit sensation via nerve fibers which unite to form the incisive nerve which pass through the incisive foramen and canal form long spheno-palatine nerve aqnd then upwards and backwards across the nasal septum to reach the spheno-palatine ganglion. Nerve endings from the palatal gingiva and muco-periosteum in the premolar and molar regions unite to form the greater palatine nerve. After passing backwards in a bony channel situated approximately half-way between the midline of the palate and the gingival margin of 9

10 the teeth, this enters its canal though the greatwer palatine foramen. It then ascends to join the spheno-palaine nerves anastomose in the canine region of the palate. The palatal muco-periosteum is firm in consistency and is closely adapted to bone. These and is closely adapted to the bone. These characteristics make it necessary to inject local anaesthetic solution under greater pressure. For this reason patients should be warned prior to injection that palatal injections cause some discomfort if not actual pain. This may be minimized by inserting the needle with the bevel facing the bone and as near as possible at right angles to the vault of the palate. The injection into the incisive papilla extremely painful and should be avoided. Palatal injections are usually given over the estimated position of the apex of the tooth to be anaesthetized. However, care should be taken to avoid injecting solution too close to the greater palatine foramen as the lesser palatine nerve may be affected which produce anaesthesia to the soft palate, tonsillar and uvular areas making swallowing difficult and causing unnecessary discomfort or distress to the patient, so that should never be given injection posterior to the 2 nd molar. The greater palatine nerve block provides anaesthesia of the palatal soft tissue distal to the canine. Although potentially traumatic is less so than the nasopalatine nerve block because the tissues surrounding the greater palatine foramen are better able to accommodate the volume of the solution are better able to accommodate the volume of the solution deposited. Technique by used short needle injected area of insertion soft tissue slightly anterior to the greater palatine foramen. The most important landmarks greater palatine foramen and junction of the maxillary alveolar process and palatine bone of the hard palate. The nasopalatine nerve block: is an invaluable technique for the palatal pain control in that with administration of a minimum volume of anaesthetic a wide area of palatal soft tissues anaesthesia. This technique is to anaesthesia anterior portion of the hard palate soft and hard tissues from the mesial of the right 1 st premolar to the mesial of the left 1 st premolar. Technique: A short needle inserted to the palatal mucosa just lateral to the incisive papilla to anaesthetized the mucosa between the incisive papilla to the distal of the canine and anastamosis between the nasopalatine nerve an greater palatine nerve at area between. 1 st and 2 nd premolar. Technique by used short needle and inserted A short needle recommended to inserts the needle at palatal mucosa just lateral to the incisive foramen. Fig.13 11

11 Fig13 Techniques of mandibular anaesthesia The nerves which originate in the teeth and their labio-buccal supporting tissues, these nerves combine to form the inferior alveolar nerve. The nerve which originate from the mucosa of lower lip and muco-periosteum of the anterior teeth and 1 st premolar combine to form the mental nerve which inter to the inferior alveolar duct, the mental foramen located at the outer aspect of the body, midway between the superior and inferior borders opposite the 2nd premolar tooth. The nerves which originate from muco-periosteum of the posterior teeth from the 2 nd premolar to the retromolar area combine to form long buccal nerve. The nerves which arise in the lingual muco-periosteum and mucosa combine with nerves from the anterior twothird of the tongue to form the lingual nerve. All these nerve pass backwards and upwards to join the mandibular division of the trigeminal nerve. Fig. 14 Fig14 11

12 The pterygo-mandibular space Due to the density of the buccal plate bone infiltration techniques are limited value in the mandibular and regional or block anaesthesia is most frequently employed. This is achieved by the deposition of solution around the inferior alveolar and lingual nerves in the pterygomandibular space. The space is bounded anteriorly by the pterygo-mandibular raphe and the fiber of superior constrictor and buccinators muscles that are inserted into it, posteriorly is formed by the parotid gland, laterally the inner surface of the ramus of the mandible, medially, the medial pterygoid muscle forms its floor and deep boundary, the lateral pterygoid muscle constitutes the roof of the space. The lingual nerve ascends diagonally backwards and upwards through the space, passing just in front of the inferior alveolar nerve which emerges from the mandibular foramen. A shallow bony depression just above the foramen is the site in which solution should be deposited for an inferior alveolar block. The long buccal nerve is arising in the cheek and buccal muco-periosteum in the molar region. After crossing the anterior border of the ramus it traverses the upper part of the space to join the anterior division of the mandibular nerve. Fig. 15 Fig15 12

13 The inferior alveolar nerve block By blocking the inferior alveolar and lingual nerves on one side, together with the long buccal nerve where necessary. It is to obtain anaesthesia from the 3 rd molar to canine. The success of this technique is almost entirely dependent upon the accurate deposition of solution. Technique: the patient is seated in the chair and head rest adjusted so that his mandibular occlusal plane is almost horizontal when the mouth is open. The dentist should stand in front of his patient for the right inferior alveolar nerve block and behind the chair whilst giving an injection on the opposite side. Upon intra-oral inspection 2 important landmarks should be identified the retromolar triangle and the pterygo-mandibular raphe (this structure passes upwards and inwards from the posterior end of the mylohyoid ridge of the mandible to the hamulus of the medial pterygoid plate, the point of insertion of the needle should be lateral to and in front of the raphe. The thumb of the left hand is passed along the buccal surface of the lower molar teeth until the external oblique ridge is felt. The tip of the thumb is then passed inward to lie in the retro-molar fossa. The mid point of the nail should lie in the deepest part of the coronoid notch; this position usually coincides with the internal oblique ridgw. A long needle is inserted at this point. With the barrel of the syringe held parallel to the mandibular occlusal plane and over the 2 nd premolar tooth of the opposite side of the mouth, the tip of the needle is inserted for about cm until its tip lightly contact the bone above the mandibular foramen. When bone is contacted withdraw approximately 1 mm to prevent subperiostal injection and about 1.5 mm of the solution deposited. Then slowly withdraw the syringe and when the approximately half its length reamains with in tissues deposit few drops of the solution to anaesthetize the lingual nerve. The onset of anaesthesia is heralded by a change of sensation in the lower lip and the tip of the tongue when compared with the other side. Fig. 16, 17 Fig16 13

14 Fig17 Anatomic variation The dimensions and shape of the mandible may vary in patients of differing race, size, and age. Thus the width of ramus and hence the position of the mandibular foramen may vary between different individuals. For this reason it is often helpful to palpate both the anterior and posterior borders of the ramus the needle directed midway between the finger and thumb. A similar approach may be employed if it is necessary to give an inferior alveolar nerve block to a very young child. The needle should be inserted in a slightly downward direction. In elderly edentulous patient gross resorption may alter the relative relationship of the mandibular foramen. As a general rule the point of insertion of the needle will be somewhat higher than in dentate patient. Long buccal nerve block The long buccal nerve provides sensory innervation to the buccal soft tissues adjacent to the mandibular molar only buccal gingiva. The main indication is during any procedure that involves manipulation of these tissues. 14

15 Technique: is achieved by mean of a sub-mucous injection in which the solution is deposited just posterior and buccal to the last molar tooth in the arch. The depth of penetration of the needle is usually only 1-2 mm. Fig. 18 Fig18 Anaesthesia of anterior teeth The lower anterior teeth are supplied by terminal branch of the inferior alveolar nerve terminate to incisive nerve. There is considerable overlap in the midline and it is this anastamosis that renders an inferior alveolar block ineffective in the incisor region. Fortunately, The labial alveolar plate in this area is thinner and more porous than elsewhere and so it is possible to use infiltration techniques. About 1 ml. of solution deposited in the labial sulcus usually suffices to produce pulpal anaesthesia but if surgery is to be undertaken up to 0.5 ml must be injected into the lingual sulcus. If anaesthesia of the incisors only is required it is possible to use labial and lingual infiltration techniques alone. Fig. 19 Fig19 15

16 The mental nerve block injection Anaesthetic solution deposited near the mental foramen enters the inferior alveolar canal to produce anaesthesia of the premolar, canine, and incisor teeth of that side. The mental foramen which is usually situated between the apices of the premolars is rarly palpable but its position may be determined by other means. The line passing vertically downwards from the supra-orbital notch and through the infra-orbital foramen will usually croo the mental foramen when the mouth is closed. Technique: The lift hand is used to reflect the lip in order to provide adequate visual ana mechanical access. About 1ml of solution should be injected over the foramen. Attempts to insert the needle into the foramen may result in damage to either the nerve or blood vessels and for this reason are contra-indicated. Fig. 20 Fig20 16

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