Injection tips

Just watched a CPD video by Dr. Townsend from Uni of Adelaide. Some tips I picked up:

-Painful injection technique involves pulling the tissues as taut as possible and having a slow injection technique
-topical anaesthetic should be applied minimally (you only need a little bit) and on dry mucosa. An effort should be made to keep saliva from washing the topical off as the taste is poorly handled.
- IDB technque:
   Level: 1cm above the lower molars, halfway between the upper and lower teeth when the mouth is wide. At the level or just above the level of the coronoid notch which is the most concave portion of the anterior border of the ramus
   Point:
Just anterior to the Pterygomandibular raphe (Join of superior constrictor muscle and buccinator muscle) which is signified by the Pterygomandibular fold
Medial to the buccal pad (not fat but fibrous tissue)
Medial to the tendonous portion of the temporalis muscle at the anterior coronoid process. This results in a point in the pterygotemporal depression between the coronoid process and the pterygomandibular fold
Midway between the anterior and posterior border of the mandible (sometimes a bit more posteriorly)
The syringe barrel should be at the location of the contralateral premolars (but can be at the molars if bone isn't contacted or more anteriorly if bone is contacted too early.
-the lingual nerve is located more medially and anteriorly to the IDN so the needle will pass by the lingual nerve on the way to the IDN. Therefore it is possible that the nerve can be hit by the needle on the way to the injection site.
-The ID artery and vein are posterior to the nerve. It is important to withdraw the needle 1mm or so after hitting bone to avoid injecting into these. Aspiration is also important. False positives can occur with blood around the injection site and you may not be in a blood vessel. False negatives can occur due to the type of syringe (non aspirating).
-With injection failures, Issues may be due to poor technique or accessory supply. Bifid IDNs can occur before entering the mandible and will be visible on an opg. use of a higher nerve block e.g Gow gates (true mandibular block) or akinosi closed mouth technique (which is halfway between the two) may anaesthetise these nerves. Structures that can block the diffusibility of the LA are the sphenomandibular ligament and even the styloid process (which can cover the lingula when the mouth is fully open)
-If the Lip and chin are numb, you would have expected the block to work. If the patient still feels pain, Suspect an accessory supply which is usually on the lingual area. A buccal and lingual infiltration will deal with this.
-Lingual infiltration occurs just off the bone at the reflection fold when the attached mucosa meets the alveolar mucosa. reatract the tongue and pull tissues tight. the needle should only penetrate 1-2mm below the mucosa (to avoid the sublingual glands) and slow injection.
-Articaine may be useful for infiltration in the anterior mandible as the bone is less dense. 3-3 is a good region for infiltration.
-Higher gauge needles e.g 30G as opposed to a 27G are thinner needles.These can be useful in PDL injections as they can reach further down the PDL. Lower gauge needles can be useful for blocks as there will be less deflection in the tissues (as blocks generally have further distance to travel).
-People who claim allergies to vasoconstrictiors may have some founding. although a true allergy to adrenaline is not possible, LA with vasoconstrictors will have an antioxidant for shelf life. Often patients are allregic to bisulphide preservatives in the LA. Use of Non vasoconstricting LA can be beneficial in these patients.

-Akinosi block should be with the teeth together, Parallel to the occlusal plane, about the level of the cusps of the upper molars medial to the coronoid process and lateral to the medial pterygoid muscle.
-Gow gates should be with the mouth wide open, about the area of the buccal cusp of the upper 7 and aiming extraorally at the tragus of the ear.