Dental Concerns: Black Lines and Tooth Discoloration Explained

Q: Dental Concerns: Black Lines and Tooth Discoloration Explained

Hello： 1. <br>Old and new fillings cannot achieve a complete seal, so if removal and replacement are necessary, it is generally recommended to remove all of the old filling material. <br>Otherwise, the junction between the old and new materials may still become discolored or dark

Inquiry Consultation

Dear Dr.
Lin,
Hello.
I have a concern regarding my upper left second molar.
There is a "U-shaped" black line on the outer side, and when I touch it, it feels like a depression, resembling a seam.
Additionally, the tooth underneath the black line appears to be "darkened." I am worried that this might indicate a crack in the tooth along with pulp necrosis causing the discoloration.
I happened to visit the dental clinic today for a routine cleaning and also consulted the dentist about this situation.
The dentist explained the following:
1.
The black line (seam) on the outer side of the tooth was confirmed by the dentist to be the junction of a resin filling and the tooth structure.
It may have become more pronounced due to bacterial or pigment accumulation.
From the outside, it appears as a "U-shaped" black line (seam).
I asked the dentist if it could be directly polished away with dental instruments, but the dentist indicated that this is not possible.
They explained that to remove the black line (seam), the resin filling would need to be excavated, the junction cleaned, and then refilled to eliminate the black line (seam).
However, since there is currently no cavity in that tooth, it is generally not advisable to perform this procedure (meaning that without a cavity, the resin filling should not be removed for replacement).
2.
Regarding the darkening beneath the black line (seam), the dentist suggested that it is likely due to pigment deposition.
After reviewing my dental X-rays, the dentist noted that my upper left second molar contains both resin and amalgam fillings, which have been in place for a long time.
Over time, this may have led to pigment deposition, resulting in the darkening of the tooth, rather than pulp necrosis.
Ultimately, the dentist diagnosed the tooth as normal and without issues, so no treatment was performed for the black line (seam) or the darkening.
Due to the limited time during the consultation, I was unable to ask the dentist many questions.
Therefore, I would like to consult you, Dr.
Lin, on the following:
Q1.
Why can't the "U-shaped" black line (seam) on the outer side of my upper left second molar be directly polished away with dental instruments? Why is it necessary to excavate the resin filling and then refill? What are the reasons that prevent direct polishing of the black line (seam)?
Q2.
As mentioned, the dentist believes that since there is currently no cavity in my upper left second molar, no treatment is necessary for the black line (seam).
In your opinion, is this approach correct? My concern is whether leaving the black line (seam) untreated might lead to future issues (e.g., increased risk of tooth cracks or secondary cavities).
Q3.
I understand that using amalgam fillings can lead to discoloration of the tooth due to pigment deposition over time.
However, does the same apply to resin fillings? Can resin fillings also cause the tooth to darken due to pigment deposition over time?
Q4.
Given that the presence of fillings (both resin and amalgam) can lead to pigment deposition causing the tooth to darken, what adverse effects or damage could this discoloration due to pigment deposition have on the tooth?
Thank you, Dr.
Lin.

A-Xiang, 40~49 year old female. Ask Date: 2022/08/15

Dr. Lin Jiayong reply Dentistry

Hello: 1.
Old and new fillings cannot achieve a complete seal, so if removal and replacement are necessary, it is generally recommended to remove all of the old filling material.
Otherwise, the junction between the old and new materials may still become discolored or darken.
2.
If there are currently no issues, it is advisable not to pursue additional treatment.
Otherwise, you may end up facing potential side effects or consequences from the treatment for concerns that have not yet occurred, which could be counterproductive.
3.
Staining of resin fillings is usually caused by external factors, such as tobacco, tea, or coffee stains, while the discoloration of silver fillings can occur due to the material itself depositing into the dentin.
4.
If you are very concerned about the color and appearance, it is recommended to directly inform your dentist that you would like to have a replacement filling.
However, you should be willing to accept the potential side effects mentioned in point 2, such as sensitivity to acidity, softness, or even weakened tooth structure that may arise from the replacement process.

Reply Date: 2022/08/15

More Info

Hello! Thank you for your detailed inquiry regarding the black line on your tooth and the associated discoloration. Let's address your questions one by one, while also providing some additional context and information about dental health.

Q1: Why can't the black line be directly polished away?
The black line you described, which is likely a result of staining or discoloration at the junction of a dental filling and the tooth structure, cannot simply be polished away for a few reasons. Firstly, the interface between the filling material (in your case, resin) and the tooth may not be perfectly sealed. Over time, this can allow bacteria and pigments to infiltrate, leading to staining. If a dentist were to attempt to polish this area without removing the old filling, the underlying issue would likely remain, and the stain could reappear quickly.

Additionally, polishing could potentially damage the tooth structure or the filling itself, leading to further complications. The recommended approach of removing the old filling and cleaning the area ensures that any decay or staining is fully addressed, and a new filling can be placed that better seals the tooth and prevents future issues.

Q2: Is it correct to leave the black line untreated?
If your dentist has determined that there is no active decay and the tooth is otherwise healthy, it may be reasonable to leave the black line untreated for the time being. However, your concern about potential future problems is valid. Leaving the black line could lead to further staining or even the risk of decay if bacteria are allowed to thrive in that area. Regular dental check-ups are essential to monitor the situation. If you notice any changes, such as increased sensitivity or pain, it would be wise to revisit your dentist.

Q3: Do resin fillings also cause discoloration over time?
Yes, resin fillings can also become discolored over time, although the mechanisms may differ from those of silver amalgam fillings. Resin materials can absorb pigments from food and beverages, leading to staining. Factors such as smoking, coffee, tea, and certain medications can exacerbate this issue. Unlike amalgam, which may oxidize and cause a darker appearance, resin discoloration is often due to external factors rather than intrinsic changes in the material itself.

Q4: What are the implications of discoloration due to pigment deposition?
Discoloration from pigment deposition can have several implications. While it may primarily be an aesthetic concern, it can also indicate underlying issues. For instance, if the discoloration is due to decay or a failing filling, it could lead to more severe dental problems, including pain, infection, or tooth loss. Additionally, if the discoloration is significant, it may affect your confidence and willingness to smile or engage socially.

In conclusion, while the black line and discoloration you are experiencing may not currently indicate a serious problem, they warrant monitoring. Regular dental visits will help ensure that any changes are caught early, and if you are concerned about aesthetics or potential future issues, discussing options for treatment with your dentist is advisable. They can provide tailored recommendations based on your specific dental health and needs. Thank you for your questions, and I hope this information helps clarify your concerns!

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