Inferior alveolar nerve block - Mandibular nerve block

Inferior alveolar nerve block is otherwise known as mandibular nerve block.The The inferior nerve block is the most useful of all nerve blocks.Bilateral nerve block ia rarely indicated because of the extreme patient discomfort produced by the bilateral soft tissue anaesthesia of the tongue which persists for several hours after injection.During this time the patient feels unable to swallow and because of the lack of all sensation is unable to enunciate well.

Nerves anaesthesised:

1.Inferior alveolar nerve:bransh of the posterior division of the mandibular nerve.

2.Incisive nerve.

3.Mental nerve.

4.Lingual nerve.

Areas anaesthetised:

1.Mandibular teeth to midline.

2.Body of mandible and inferior portion of ramus.

3.Buccal mucoperiosteum and mucous membrane anterior to mandibular first molar.

4.Anterior two thirds of tongue and floor of oral cavity.

5.Lingual soft tissues and periosteum.

Indications:

Procedures on multiple mandibular teeth in one quadrant.

2.When buccal soft tissue anaethesia is required.

3.When soft tissue anesthesia is required.

Contraindications:

1.Infection or acute inflammation in area of injection.

2.Young children who might bite either the lip or tingue and also physically or mentally handicapped patients.

Advantages:

One injection provides wide area of anaesthesia.

Disadvantages:

1.Wide area of anaesthesia for localized procedures.

2.Rate of inadequate anaesthesia.

3.Intraoral landmarks not consistently reliable.

4.Positive aspiration rate is the highest.

5.Lingual and lower lip anaesthesia discomforting to many patients.

6.Partial anesthesia is seen in bifid mandibular canals.

Alternatives to inferior alveolar nerve block:

1.Mental nerve block.

2.Incisive nerve block.

3.Supraperiosteal injection for central and lateral incisors and canine.

4.Gow-Gates mandibular block.

5.Periodontal ligament injection for pulpal anaesthesia.

6.Intraseptal injection for osseous and soft tissues.

Technique:

25 gauge needle is requied for this anaesthesia.Area of insertion is the mucous membrane on the medial border of ramus of mandible and at a point of intersection between two lines – one horizontal representing height of injection and the other vertical representing anterior-posterior plane of injection.The target area will be the inferior alveolar nerve as it passes downward toward mandibular foramen but before it enters the foramen.

The landmarks are the coronoid notch which is the greatest depression on the anterior border of the ramus,the pterygomandibular raphe and the occlusal plane of mandibular posterior teeth.For the right alveolar nerve block,the dentist should sit in a 8 o’clock position.For the left inferior alveolar nerve block,the dentist should sit in 10 o’clock position.The position of the patient should be supine or semi supine during the injection.

Complications:

1.Haematoma:

Swelling of tissues of the medial side of ramus of mandible following deposition of local anaesthetic solution.

2.Trismus:

Muscle soreness or limitation of movement of muscle.

3.Transient facial paralysis:

This is produced by deposition of local anaesthetic solution on posteromedial aspect of the parotid gland.

Clinical signs and symptoms of allergy - Respiratory reactions

Respiratory reactions:

Clinical signs and symptoms of allergy may be related to the respiratory tract.Bronchial asthma is the classical respiratory allergic response.The signs and symptoms include

1.Respiratory distress.

2.Dyspnoea.

3.Wheezing.

4.Flushing.

5.Cyanosis.

6.Perspiration.

7.Tachycardia.

8.Increased anxiety.

9.Use of accessory muscles of respiration.

Laryngeal edema is an extension of angioneurotic edema to the larynx produces swelling of the vocal apparatus with subsequent obstruction of tha airway.Little or no exchange of air from the lungs is possible.Larngeal edema represents the effects of allergy on the upper airway.Bronchial asthma represents actions of allergy on the lower airway.

Clinical signs and symptoms of local anaesthetic overdose

Clinical signs and symptoms of local anaesthetic overdose appear when the anaesthetic blood level in an organ rises to an overly high level for that individual.

Minimal to moderate overdose levels:

Signs-

1.Talkativeness.

2.Apprehension.

3.Excitability.

4.Slurred speech.

5.Generalised stutter leading to muscular twitching and tremor in facial muscles and distal extremities.

6.Elevated blood pressure.

7.Elevated heart rate.

8.Elevated respiratory rate.

Symptoms:

1.Feeling of lightheadedness and dizziness.

2.Inability to focus.

3.Tinnitus.

4.Drowsiness and disorientation.

5.Loss of consiousness.

Moderate to high overdose levels:

Generalised tonic-clonic seizure activity followed by generalised CNS depression,depressed blood pressure,heart rate and respiratory rate.

The excitatory phase may be brief and can lead to drowsiness which in turn can progress to unconsciousness and later respiratory arrest.This can happen so quickly.The local anaesthetic reactions will happen till the blood level of the local anaesthetic in the brain or heart falls below the minimum blood level or until clinical signs and symptoms are terminated through use of appropriate drug therapy.

Osseous defects

Osseous defects are the bone changes that are associated with periodontal disease other than the horizontal bone loss.

1.Interproximal crater:

Interproximal crater is a trough like or saucer shaped defect occuring in the alveolar crest of the interproximal bone.The bony defect has four walls – the buccal and lingual cortical plates and the roots of two adjacent teeth.The marginal bone of the interproximal crater appears thin.

2.Proximal intrabony defect:

Proximal intrabony defect is a vertical defect of the bone extending from the crest of the alveolus and in an apical direction.It is a defect  surrounded by four walls,the buccal and the lingual cortical plate,the hemiseptum and the root of the involved teeth.Radiographically the proximal intrabony defect appears “v” shaped adjacent to the affected root surface.

3.Interproximal hemisepta:

A hemiseptum is defined as the bone of the interdental septum that remains on the root of the uninvolved adjacent tooth after destruction of either the mesial or the distal portion of the interproximal bone septum.The hemiseptum results due to the loss of bone on the mesial or the distal aspect of a root surface.Radiographically the hemiseptum is a “V” or “U” shaped.

4.Inconsistent bony margins:

Inconsistent bony margins refer to irregular resorption of the cortical bone of the buccal or lingual alveolar cortical plate.Radiographically this bony change appears as irregular loss of the height of the alveolar crest.

5.Bony pockets:

Bony pockets usually occur together with proximal bony defects.Bony pockets are seen on the buccal aspect of the roots.Radiographs may not be very useful in the diagnosis of bony defects on the buccal or the lingual cortex.

Luxation

Luxation of the teeth refers to dislocation or loosening of the teeth due to loss of the periodontal attachment.The loosening can be

a.Intrusive luxation:

Intrusive luxation results when the tooth is displaced in to the alveolar bone.

b.Extrusive luxation:

Extrusive luxation refers to displacement of the tooth out of the socket.

c.Lateral luxation:

In lateral luxation the tooth is displaced to the side.

Luxation involves the anterior teeth.The clinical features that are seen are :

1.The affected tooth may be mobile.

2.Bleeding is seen through gingival crevice.

3.There is tenderness on percussion.

In intrusive luxation the tooth will be pushed in to the socket and the crown length appears shortened.In extrusive luxation the tooth will be pushed out of the socket and the crown lenth appears elongated.

The radiographic changes seen are as follows.In intrusive luxation there is disruption of the continuity of the lamina dura in the apical region.In extrusive luxation there is widening of the periodontal ligament space in the periapical region which is radiographically apparent as periapical radiolucency.In case of lateral luxation there is widening of the periodontal ligament space on one side and obliteration of the periodontal ligament space on the other side with evidence of damage to the lamina dura of the involved side.Either pulpal necrosis or calcification of the pulp chamber and the root canal can occur eventually which will be radiographically eveident as periapical lesion or obliteration of the pulp chamber and the root canal.

Juvenile periodontitis

Juvenile periodontitis or periodontosis is characterised by severe and rapid loss of the alveolar bone.Familial pattern of  distribution of this disease is also known as a result of genetic transmission of susceptibility.

There are two forms of Juvenile periodontitis – Localised and generalised.

The localised form is characterised by angular bone loss involving the first molars and the incisors.There can be no irritants seen also in some cases.The maxillary teeth are involved more than the mandibular teeth  and the teeth are involved bilaterally.The onset of Juvenile periodontitis is usually after adolescence.The affected individuals have an inherited defetc of neutrophil chemotactic function.

In the generalised form of Juvenile periodontitis there is involvement of many teeth.It usually has a late onset occuring between ages 20 and 30.Apart from the premolars and the incisors,the generalised form involves the canines,the premolars and the second molars.It is also considered as an extension of the local form.

Concussion

Concussion is a traumatic injury that involves the tooth.There is crushing injury to the apical vasculature and the periodontal ligament of the apical region leading to inflammatory edema.Thus it involves the supporting tissues of the teeth.As there is accumulation of inflammatory edema in the apical region,the affected person will suffer from pain.The involved tooth may be slightly elevated from the socket.This results in pain while biting.The radiographic change that is noticeable in concussion in widening of the periodontal ligament space at the apex.Evidence of pulpal necrosis and periapical lesion may be noted after a variable period of time.

Buccal and lingual caries

Buccal caries involves the buccal tooth surface and lingual caries involves the lingual tooth surface.Clinical examination is more useful and important in the diagnosis  of buccal and lingual caries as radiographically it may not always be possible to detect caries due to superimposition of the dense normal tooth structure.It is also not definitely possible to differentiate between buccal and lingual caries based on a radiograph.If buccal and lingual caries is radigraphically detectable,it appears as a small circular radiolucent area surrounded by dense area of normal tooth structure.

Recurrent caries

Secondary or recurrent caries occurs adjacent to a restoration.

The predisposing factors are:

1.Marginal leakage.

2.Defective margins of restoration.

3.Fracture of restoration in the marginal region.

4.Incomplete removal of caries.

5.In adequate cavity preparation.

Radigraphically recurrent caries appears as a radiolucent areabelow or adjacent to a radiopaque restoration.

Radiation caries

Radiation caries

Radiotherapy involving the head and neck region with resultant irradiation of the salivary glands causes:

1.Decreased saliva secretion.

2.Increased viscosity of the saliva.

3.Acidic pH of the saliva.

4.Loss of buffering capacity of the saliva.

These factors contribute to the development of caries.Three types of radiation caries have been seen.

They are:

A.First type of radiation caries that involves the cementum and dentin in the cervical region of the teeth.It progresses around the teeth.

B.The second type is the superficial lesion involving the buccal,occlusal,incisal and palatal surfaces.

C.The third type appears as dark pigmentation of the entire crown.