What Causes a Tooth Filling to Turn Black, and Why Does It Sometimes Cause Pain?

What Causes a Tooth Filling to Turn Black, and Why Does It Sometimes Cause Pain?

December 15, 2023

If you’ve had a tooth filling done in the past, you may notice it starts to change color and turn black over time. This darkening of dental fillings is common but can be alarming if you don’t understand what’s causing it. Blackened fillings aren’t necessarily a cause for concern, but they can indicate issues with the filling that need to be addressed. Additionally, you may experience pain or discomfort from the filled tooth.

Understanding Tooth Fillings

Dental fillings, also called dental restorations, are materials to restore teeth damaged by decay, infection, or fracture. The purpose of fillings is to repair the tooth structure, prevent further decay, and restore function and appearance. The most common materials used for direct fillings are dental amalgam, composite resin, glass ionomer cement, and porcelain.

Dental amalgam is a metal alloy composed mainly of mercury, silver, tin, and copper. It is durable but visible as a silver filling and can darken over time. Composite resin is a plastic dental material made from inorganic filler particles blended with an acrylic resin. It can be shaped, improved, and polished to match the color of natural teeth but may not last as long as other filling materials.

Why Do Fillings Turn Black?

There are a few reasons why tooth fillings may change color and become black or dark over time:

  • Oxidation – The metals in dental amalgam can undergo oxidation and react with sulfur, causing the filling to tarnish and turn black. This is a normal process that happens over time.
  • Wear and tear – As the edges of the filling wear down, the metals become exposed and can oxidize and turn black more readily. Older fillings show this wear and often have black lines at the edges.
  • Leakage – If gaps form between the filling and the tooth, fluids can seep underneath the filling and cause oxidation and discoloration. This can indicate deterioration of the bond with the tooth structure.
  • Galvanic shock – When two dissimilar metals touch, like amalgam and gold crowns, galvanic shock can corrode the metals and turn the filling black or dark grey.
  • Dietary stains – Foods and drinks that are acidic or pigmented, like coffee, tea, or berries, can stain the corroded edges of an old filling. Regular dental cleanings can minimize this type of staining.

Painful Fillings: What Causes Discomfort and Sensitivity?

In addition to the change in color, a blackened filling may also start causing pain or discomfort while eating or drinking cold or hot foods. There are several reasons why an old filling might become sensitive or painful:

  • Tooth decay – If new decay forms under the edges of the old filling, it can irritate the nerve and result in pain and sensitivity. The decay allows fluid flow and bacterial inflammation of the inner tooth structure or pulp.
  • Cracked tooth – Fractures and cracks can form in the remaining tooth structure years after the filling is placed. This allows fluid infiltration and results in pain upon chewing pressure. Cracked cusps under an old filling are common.
  • Deteriorating filling – Composite and amalgam fillings can weaken, rust, and deteriorate over time. As gaps form, they allow thermal stimuli and bacterial penetration that irritates the inner tooth and causes pain.
  • Exposed root surface – If the filling leaks over time, the loss of outer enamel can expose the softer dentin layer underneath. This root sensitivity is exaggerated by hot, cold, sugary, or acidic foods.
  • Bruxism – Nighttime teeth grinding or clenching can place extreme pressure on dental fillings and cause cracking or movement, leading to sensitivity. Worn teeth near an old filling are prone to fracture.

How Dentists Diagnose and Treat Blackened Fillings

If you notice color changes or discomfort from an old filling, call your dentist at 48723 to have it evaluated. The Caro, MI, dentist will look for signs of decay, cracks, leakage, and deterioration and examine your bite. They may take X-rays to look for hidden problems under the darkened filling. Testing with dental instruments allows evaluation of pulp health and sensitivity.

Based on the examination, different treatment options may be advised:

  • Monitoring if the filling is still intact with no problems
  • Replacement with a new filling to prevent worsening cracks or decay
  • Crown placement if the tooth is fractured and needs more extensive repair
  • Root canal if pulp inflammation and infection have set in under the aged filling
  • Tooth extraction and implant if severely damaged or decayed

Routine dental exams and cleanings in Caro allow early detection of damaged fillings before they turn painful. Always replace blackened, worn, or leaking fillings to prevent more invasive treatments.

Tips for Maintaining Fillings and Preventing Issues

To keep your dental fillings intact and prevent painful problems down the road:

  • Maintain oral hygiene through regular brushing, flossing, and using antiseptic mouthwash to avoid decay near fillings.
  • Minimize consumption of sweet and acidic items to protect the integrity of filler bonds in your teeth.
  • Avoid chewing hard items like ice, nuts, and hard candy that fracture teeth with fillings.
  • If you grind your teeth, get a mouthguard to reduce cracking or chipping fillings.
  • Visit your dentist every six months for examinations and professional cleanings.
  • Have old, failing, or blackened fillings replaced promptly before new decay forms.

Some amount of tooth filling discoloration and wear is expected over the lifespan of a tooth filling, but significant color changes can indicate issues that need dental attention. Stay on top of your oral health and schedule regular dental visits at Thumbs Up Dental in Caro, MI, for dental filling repair, longevity, and comfort. Prompt replacement of failing restorations prevents more extensive treatments down the road.