Injection Aparatus

Injection apparatus

Syringes should be easily cleaned and sterilized. They mostly take anaesthetic solution pre-packed in cartridges. These are shipped into syringe and pierced by the reverse end of the needle which has previously been placed in position.


 This is obtained in a variety of lengths and diameters. It is easier to penetrate the tissues with thinner needles, but these are more readily broken. They are sometimes tempered, the tip being finely pointed, but the part nearest to the syringe being thicker for added strenght.
Long needles with short hubs are used in situations where the tip have to travel through a great deal of tissue, in an inferior dental block for example. In other cases, maximum protection is afforded by short needles used with a long hub.
  The same needle must never be used for more than 9ne patient, as there is a risk of passing on the virus causing serum hepatitis.
In recent years, it is common to use needles pre-sterilized in the factory by exposure to gamma rays.

Types of injections

  1. Regional blocks: inferior dental, metal, infra - orbital, posterior superior dental, greater palatine, sphenopalatine.
  2. Infiltration.
  3. Papillary.
  4. Intra osseous.
Read: injections antibiotics and other medicines.
          -   Local and General anaesthesia.

Inferior Dental Blocks

  The needle is inserted into the tissues behind and above the last lower molar tooth. This causes anaesthesia of the inferior dental and lingual nerves, owing to their close proximity. Anaesthesia of the inferior dental nerve results in loss of sensation of all the lower teeth, and therefore suitable for cavity preparation. However, for extractions, a supplementary buccal injection is also given. As the lip is also anaesthetized, patients must be warned to beware of biting it.

Infra-orbital and mental blocks

In these cases the needle is inserted into the mucosal reflection close to the corresponding foramen.

Posterior superior Dental Blocks

Here the solution is injected distal to the Maxillary tuberosity.

Greater and sphenopalatine blocks

  As the palatal mucosa in these regions is firmly bound down to bone, these injections are given very slowly to prevent pain from excessive pressure on nerve endings.


 Injection is made at the buccal reflection of mucosa overlying the root apex or site of operation.


The needle is inserted directly into the interdental papilla.

Intra - osseous

  When difficulty occurs in anaesthetizing a tooth for cavity preparation, a hole may be drilled through the bone itself, an anaesthetic solution actually placed into the hole. This is rarely used.

Complications following injections

  1. Fainting
  2. Failure of anaesthetic: due to faulty technique, old stock of solution, or anatomical variation.
  3. Swelling: This is caused by oedema fluid, allergic response, or injection into a vein.
  4. Pain: the pain is decreased by using sharp needles, and injecting slowly.
  5. Broken needle: immediately a pair of artery forceps must be hand over to the dentist to grip the part of the needle remaining in the tissues.
  6. Needle infection: to prevent organisms from being carried into the tissues, the mucosal surface is swabbed with antiseptic prior to injections with a sterile needle.


DENTAL CARE 3071983449868805990

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