Is this gap between my crown and gum normal?

Do you know how a properly fitting crown should sit on your natural tooth?

While dental crowns are designed to last for years or decades, any gap or defect can create an open door for bacteria, causing the crown to fail too soon.

So, what should you do if you notice a space between your crown and gum?

Before jumping to conclusions, it’s important to tell the difference between a normal crown margin and a "BAD" gap that needs treatment.

In this post, we’ll break down what can cause a gap to appear, when it’s time to worry, and the treatment options available.

What does a "bad" gap between crown and gum look like?

A bad gap is when there's an open space between the dental crown and the underlying tooth, creating a space where bacteria and food particles can easily get in.

The crown must be firmly attached to the tooth, leaving no gaps. Any defects or leakage under the crown can make the tooth more vulnerable to issues like cavities and infections.

When there's this kind of gap, it's often noticeable with darkening along the gum line, decay, and a crown that feels looser and less stable.

A gap between the crown and gum can actually mean the crown's normal placement

It’s important to tell the difference between a “bad gap”, where there’s a space between the crown and the underlying tooth that allows leakage, and a normal space that simply represents normal crown placement.

The crown margin is the edge where the crown meets your tooth.

The crown margin can be placed in different positions. One common position, especially for back teeth, is supragingival, which means the crown sits above the gum line.

If your crown is in a supragingival position, it's completely normal to see a space between the crown and your gum. What you're seeing isn’t a gap—it’s your natural tooth showing. The color contrast between the crown and your tooth might make it look unusual, but it’s not a problem.

As long as there’s no leakage under the crown, there’s no reason to worry.

Your dentist has intentionally chosen this placement for biological reasons. That's because the supragingival margin is the healthiest for your gums and makes oral hygiene and cleaning easier.

The downside? It's less aesthetic than other options (since the transition between the crown and the underlying tooth is clearly visible).

There are also other types of crown margins your dentist can choose from:

• Subgingival: The crown margin is concealed and placed below the gum line. This is the most aesthetically pleasing position but the most harmful to gum tissue.


• Equigingival: The crown margin is positioned at the same level as the gum line. It is less aggressive than the previous one but also requires regular care.

How Should a Well-Fitting Crown Look Like?

A good-fitting crown can protect your tooth and increase its lifespan. On the other hand, an ill-fitting crown can actually do the opposite and cause problems like cavities, gum disease, and infections.

So, what should a good-fitting crown look like?

• Full coverage with no gaps: The crown should completely cover the tooth, leaving no spaces where bacteria or saliva can seep in. It must be securely attached and stay stable when you chew or brush.


• Proper height and width: The crown should fit well with your neighboring teeth—touching them lightly and matching their height. If it’s too high or puts pressure on nearby teeth, it can cause tension, wear, sensitivity, or bite problems.


• Gentle on the gums: There should be no gap between the crown and the tooth, as this can lead to plaque buildup and gum irritation. At the same time, the crown shouldn’t press too deep into the gum line, which could damage the tissue and lead to receding gums and bone loss.

Warning signs

Some signs that may indicate an unhealthy gap between crown and gum include:

1. Flossing Difficulty: If floss keeps catching or tearing in the area around the crown, it could be a sign that the crown doesn’t fit properly.


2. Surface Roughness: Try running a toothpick gently along the crown margin—the area where the crown meets your tooth. If it catches or feels rough and uneven, it could be a sign of a gap underneath the crown.


3. Discoloration, Foul Smell, and Taste: Black staining along the crown margin, soft white material oozing from the gap, a persistent bad taste, or bad breath may all point to a defect in the crown—possibly even decay developing underneath.

Complications of an open gap between the crown and gum

If left unchecked, a leak under the crown can lead to many complications:

• Increased Plaque Buildup: Gaps can promote more bacterial plaque buildup. And more bacteria means a higher threat to your oral health.


• Cavities: Bacteria and debris can accumulate in the gap, leading to tooth decay.


• Receding Gums: Gaps can contribute to gum recession, leaving the tooth root exposed.


• Gum Disease: Difficulty in cleaning the gap can lead to gum inflammation and periodontal disease.


• Crown Loosening: By damaging the tooth, the gap can make the crown loose.


• Bone Loss: Untreated gaps can lead to bone breakdown around the affected tooth.


• Tooth Infection: Infection and abscess formation are common complications.

What may cause a gap between the crown and gum?

There are several potential reasons why a gap may appear between your crown and gum.

• Improper Crown Preparation: Technical errors during the crown preparation process can result in a poorly fitting crown. If the crown is not placed correctly, it can develop leakage around its borders.


• Aging or Worn-out Crown: Over time, even well-made crowns can show signs of wear and aging. The cement that holds the crown to the tooth may deteriorate, causing the restoration to wear and loosen.


• Cavity Formation: Recurrent or secondary cavities can occur under a crown due to factors such as poor oral hygiene, a poorly fitting crown, or incomplete removal of initial decay.
  The decay will gradually eat away at the underlying tooth and cement, leading to crown failure.


• Gingival Recession: This happens when the gum pulls away from the crown. As a result, the distance between the crown margin and the gum line gets larger, making your tooth look longer than before.
  The tricky part is that gingival recession can worsen over time, potentially causing problems like root decay, tooth sensitivity, and cosmetic concerns.

Treatment Options to Fix the Gap Between Your Crown and Gum

When a gap exists between your crown and gums, there are several treatment options available to address the issue:

1. Replacement of the Crown: In most cases, your dentist will recommend replacing the old crown with a new, properly fitting one. This ensures a better seal and prevents further complications.


2. Addressing Underlying Problems: Before placing a new crown, any existing problems need to be taken care of.
   If there's a cavity, it will be removed and filled with dental material. If there's a tooth infection, a root canal treatment may be needed before the new crown is placed.


3. Treating Receding Gums: If the crown is securely in place, and the "gap" you are dealing with refers to receding gums, a different approach may be considered.
   Treatment may involve deep dental cleaning, known as scaling and root planing, to remove plaque and infected tissue. In some cases, your dentist may recommend a gum graft procedure to cover the exposed root and restore your tooth's appearance.