There are two main types of stains that can prevent your teeth from having a characteristic white glow. Extrinsic stains are the outer stains that are nearer to the surface of the tooth. They are easier to remove and are responsive to a wide variety of whitening methods. In fact, extrinsic stains can be removed via household remedies and other whitening products that you can apply yourself. 

On the other hand, intrinsic stains are located deep within the enamel. These stains often require special teeth whitening methods because the stains occur as part of the formation of the tooth.    

What causes intrinsic staining?

Intrinsic stains are caused by various factors that occur during tooth formation and growth. As opposed to extrinsic stains that merely adhere to the surface of the enamel, intrinsic stains occur when the teeth are forming or as a result of long-term dietary choices. Some of the most common causes of intrinsic stains include:

1. During tooth formation 

During the early stages of tooth formation, molecules with dark pigments sometimes penetrate the tooth structure and are embedded into the crystals of the tooth. These pigments become etched deep within the enamel and manifest themselves as intrinsic stains. 

In some cases, the dark pigments can occur due to antibiotics that are administered when teeth are continuing to grow. 

2. After tooth injury

When a tooth is injured, the body supplies more blood to the tooth to facilitate healing and the formation of a blood clot. The increased blood supply may cause pigments of iron (that are reddish-brown in colour) to become deposited in the inner layers of the tooth. 

This often results in dark brown stains within the enamel, which can be difficult to remove.  

3. Dietary choices 

Perhaps the most common cause of intrinsic stains is excessive fluoride consumption. Fluoride from water sources and food items can deposit deep within the enamel and cause the teeth to appear brown. 

Treatment for intrinsic stains 

Intrinsic stains require a more specialised whitening process than extrinsic stains. Treatment involves two main approaches: covering the tooth surface so stains don't appear or removing the intrinsic stains from deep within the enamel. 

Dental veneers, tooth replacement and dental crowns are common treatment options for covering up deeply stained teeth. If you wish to have the stains permanently removed, you can also opt for deep bleaching. In this whitening approach, a bleaching agent is placed inside the enamel and left to remove fluoride or iron deposits for a period of a few days. 

If the intrinsic stains are a result of a decaying tooth, it is sometimes better for the tooth to be extracted and replaced with implants.