External Discolouration: Can be caused by diet, wine, coffee, tea, tobacco, plaque, mouth rinses, etc. These stains can usually be removed with a scale and polish by your Dentist or Dental Hygienist.
Internal Discolouration: Can be caused by, pulp necrosis from dental decay or intrapulpal haemorrhage as a result of trauma, leakage around old fillings, some old root filling materials, aging - either natural or accelerated ( as a result of trauma or a deep filling), drug related e.g., tetracycline antibiotic.
The majority of discoloured teeth either have necrotic pulps or are already root filled.
Breakdown of red blood cells inside the tissue release iron products which react with hydrogen sulfates from bacterial metabolism. The resultant iron sulfates that form produce a grey discolouration. When you have bleed into soft tissue ( bruise) the red blood cells are removed over time by macrophages supplied by the surrounding blood vessels. When the pulp in your tooth becomes necrotic, the blood supply ceases. The tissue inside the tooth breaks down but cannot be removed by your immune system, hence the persistent stain. These products gradually diffuse through the porous dentine of the tooth towards the external surface.
Root canal treatment removes this tissue and produces an environment favourable towards healing. The space remaining within the crown after endodontic access can now be used to apply bleaching agents to remove the discolouration.
Discolouration of the tooth is indicative of microleakage around existing fillings and therefore bacterial contamination of the root canal system. The old root fillings removed, the canal disinfected, refilled and sealed at the entrance to the root canal. ( see Retreatment)
We use a mild bleaching agent called sodium perborate which is mixed with water and sealed inside the crown with an adhesive restorative material. The solution slowly releases hydrogen peroxide into the surrounding tooth structure removing the discolouration. The bleaching material is left inside your tooth until an acceptable level of tooth whitening is achieved. In some cases several applications maybe required. After completion of bleaching the cavity is filled and sealed with a bonded tooth coloured restorative material.
In severely discoloured teeth an ideal result cannot be achieved but the tooth can usually be lightened to a level that will allow for an improved result with a porcelain or ceramic crown.