Syndromes Relevant to Dentistry

The word syndrome is derived from greek and means 'runs together'. Syndromes refer to medical conditions that have signs and symptoms that often occur together. A syndrome has no known cause, but may still be referred to as a syndrome even after the cause has been discovered, e.g. AIDS. If a dentist is alerted to one or more signs and/or symptoms of a suspected syndrome, they should look out for the other common signs and symptoms of the syndrome.

Neural Crest Syndromes

• DiGeorge Syndrome - remember the description of this syndrome with the mnemonic CATCH 22 - Cleft palate, Abnormal facies, Thymic aplasia, Cardiac defects, Hypocalcaemia, 22q11.2 deletion. May be caused by migration defects of neural crest derived tissues.
  
• Hemifacial microsomnia - lower half of face affected (on one or both sides). Most commonly mouth, mandible and ears.
• Sturge-Weber Syndrome - most obvious feature is a port-wine stain on the face. Neurological abnormalities are also commonly seen as angiomas can develp on the brain (the same side as the port-wine stain). Glaucoma also commonly develops. Increased vascularity of the hard and soft tissue of the jaw on the same side as the port-wine stain may occur and this can cause dental problems such as swelling, premature tooth eruption and periodontal problems.
  
• Thalidomide malformations - phocomelia (very short or absent long bones). (S) enantiomer of thalidomide thought to be the neural crest toxin.
  
• Treacher-Collins - often present with underdeveloped facial bones, micrognathia, microtia, cleft palate. Half have hearing problems due to defects in middle ear bones.
  

Inferior Alveolar Block

There are 3 methods of achieving inferior alveolar block: Direct, Gow-Gates, and Akinosi. I will only cover the Direct method here.

Direct method
Your thumb should be positioned on the coronoid notch of the mandible as shown in the adjacent photo and your first finger should be positioned on the posterior border of the ramus on the patient's jaw.

We anaesthetise the inferior alveolar nerve by inserting the needle about 1 to 1.5 cm above the mandibular occlusal plane and about halfway between the coronoid notch and the pterygomandibular raphe. If the barrel of the syringe is over the contralateral premolars, then the angle will be about right.

Push the needle in until bone is felt (a depth of 2-3 cm usually), then withdraw the needle slightly away from the bone - the end of the needle should now be in the pterygomandibular space. Now aspirate to ensure the needle isn't in the inferior alveolar artery or vein before slowly injecting the local anaesthetic into the pterygomandibular space. We inject here because this is where the inferior alveolar and lingual nerves can be found.

Provided this was done correctly, after a few minutes the entire bone, periodontium, gum and teeth of the side injected will be anaesthetised. A bit of the tongue, the lip and the skin on the chin will also be anaesthetised on that side.

Complications
Never buy pink pills from turban headed indian liquor shop owners. That's the mnemonic to remember the complications of anterior alveolar nerve block.

• Never - Needle Breakage
  
• Buy - Bruising
  
• Pink - Pain
  
• Pills - Paraesthesia
  
• From - Facial paralysis
  
• Turban - Trismus
  
• Headed - Haematoma formation
  
• Indian - Infection
  
• Liquor - Lip biting
  
• Shop - Sloughing
  
• Owners - Oedema

Other complications are transmission of infections, fainting, and methaemoglobinaemia (prilocaine and benzocaine).