Sillim Dental Clinic: An Old PFM Crown on the Lower Front Tooth, Cervical Metal Show-Through, and an Apical Lesion Treated with Root Canal Therapy Followed by Zirconia Aesthetic Prosthetic Restoration

Treatment period: 2026.01.04 ~ 2025.02.12

Hello,

This is Director Park Jeong-gi of Seoul Remember Dental Clinic in Sillim.

Among patients who have an old crown in the mouth,

the border where the gums and tooth meet,

that is, the cervical area, may appear dark,

and they often visit because it looks as if decay has formed.

However, when we actually examine it,

it is not decay,

but rather a case where the fit of the old prosthesis has deteriorated,

causing the internal metal to become exposed,

and it is highly likely that it has been seen as black by the patient’s eyes.

As there are quite a lot of patients who come in for this reason,

today at Sillim Dental Clinic

I will show you a related case,

so please stay focused and read to the end.

1. First visit

2026.01.04

Can you see the restored PFM crown on the lower right front tooth (tooth 41)?

This is a type of prosthesis made of porcelain on the outside

and metal on the inside,

and because it is relatively inexpensive,

many people chose it in the past.

However, as time passes,

it has a higher possibility of fracture,

and, as in this case, the metal becomes visible at the margin,

which limits its esthetics.

In this case as well, metal is visible along the cervical line,

significantly reducing esthetics.

2. Diagnosis of the cause of pain

If the only issue were reduced esthetics,

it would be enough to simply replace the crown,

but before that, we need to take an X-ray

and check whether the root condition is okay.

Sometimes a tooth that has already been restored with a prosthesis can still hurt,

so in such cases, it is better to take a periapical radiograph

and begin after making an accurate diagnosis.

2026.01.04

This case was also accompanied by slight pain,

so when we took a periapical radiograph at Sillim Dental Clinic,

a dark shadow was confirmed at the root tip.

This dark area is the apical lesion.

Simply put, it means that inflammation caused by bacterial infection has accumulated around the tip of the tooth root.

If secondary decay develops beneath the PFM crown,

or if the internal seal is incomplete and bacteria infiltrate,

infection can progress to the root tip over time.

And because many cases remain without any particular symptoms until one day pain and swelling appear,

at Sillim Dental Clinic we first check the root condition with a periapical X-ray

before starting treatment.

3. Root canal therapy needed

In this case, an apical lesion was confirmed,

so root canal therapy is necessary.

This is the process of removing the infected pulp tissue inside the natural tooth,

disinfecting the root canal,

and sealing the empty space.

Many patients are afraid of root canal therapy,

but because it is performed under local anesthesia,

there is almost no pain during the procedure.

Rather, since this is the process of removing the inflammation that was already present,

pain decreases after treatment,

so even at Sillim Dental Clinic,

there are actually more patients who are pleased because it no longer hurts.

4. Aesthetic prosthetic restoration

A tooth that has completed root canal therapy

can break easily from external impact.

Therefore, it must be protected with a crown.

In this Sillim Dental Clinic case,

because it was the lower front tooth area,

esthetic appearance was even more important,

so to avoid the problem seen with the existing PFM crown,

where the internal structure is made of metal and over time the metal edge becomes visible at the cervical area,

we decided to use zirconia.

2026.02.12

Zirconia

is made of a monolithic porcelain material

with excellent strength and durability,

and it can reproduce color and texture that are closest to natural teeth.

Because of this, there is no problem of cervical discoloration like before.

Taking into account the patient’s dental alignment, interdental spaces, shade,

length, and cervical line,

we restored the tooth naturally with an aesthetic prosthesis as well,

and now it should be used while being monitored through regular checkups to make sure the apical abscess does not recur.

If an old prosthesis has worn down

and deformation or discoloration has occurred,

there is a high chance that the abutment tooth has also developed a problem.

Therefore, even if there are no symptoms,

please remember that regular checkups are necessary

so you can protect your precious teeth for a long time.

Thank you for reading.

This was Director Park Jeong-gi of Seoul Remember Dental Clinic in Sillim.