English Home › Clinical Cases & Doctor’s Columns › Clinical Case

A Molar That Trapped Food for a Year — Rebuilt from the Contact Point with a Same-Day Inlay

Clinical case · Published 2026.08.29 · Translated from the Korean original · Seongmo Dental Clinic, Seongbuk-gu, Seoul

“The molar was treated a year ago, but every time I eat, something gets stuck between the teeth. I went back several times and nothing changed.” That is why a patient in his 20s, who had made time on a Saturday morning, came to Seongmo Dental Clinic.

Why did food keep getting trapped next to a treated molar for a whole year?

Food impaction happens when the contact point between two teeth is loose or open, so that chewing forces push food into the gap.

This patient told us that after the upper right second molar (#17) was treated a year earlier, food started getting stuck between it and the tooth in front (#16), and that several follow-up visits had not changed anything. At the first examination at Seongmo Dental Clinic we took both a full panoramic X-ray and a periapical X-ray. Dentin caries on the distal proximal surface of #16, which was hard to read on the panoramic image, was confirmed on the periapical X-ray. This is consistent with reports that intraoral bitewing and periapical images detect proximal caries more accurately than panoramic images (Akarslan et al., 2008).

Food impaction is observed more often where a contact is open, and deeper periodontal pockets have been reported at sites with impaction (Hancock et al., 1980). In a study of 104 adults with an open contact on one side only, the pockets on the open side were on average 0.27 mm deeper and attachment loss was 0.48 mm greater (Jernberg et al., 1983). A proximal surface where food gets trapped cannot be reached by a toothbrush, is not cleaned, and is an easy place for caries to start. This patient’s distal caries on #16 was found exactly there, right under that contact point.

If impaction started after a treatment, repeats at one particular site, or the floss slips through without any resistance, the contact point is the likely cause. In that situation the answer is to restore the area and rebuild the contact point at the same time.

Conversely, when the gum has receded and a black triangle has opened between the teeth, when a tooth has tilted or drifted so that the space itself has widened, or when a sharp cusp of the opposing tooth wedges food in (a plunger cusp), an inlay alone will not solve it. Those situations call for periodontal treatment, bite adjustment or an orthodontic assessment first, and Seongmo Dental Clinic makes that distinction at the first examination.

Why did Seongmo Dental Clinic near Sungshin Women’s University choose a same-day ceramic inlay for #16?

An inlay is a partial restoration: the cusps are kept, only the decayed area is prepared, and a ceramic piece is fitted and bonded into it.

Seongmo Dental Clinic considers the options in order of how little tooth structure they remove — ① direct resin filling → ② ceramic inlay → ③ onlay or overlay → ④ full crown. This tooth had a Class II (DO) cavity with a collapsed distal marginal ridge, but the buccal and lingual cusps were sound. There was no reason to cover the cusps, so ③ and ④ were ruled out. The principle of not over-treating is applied at exactly this kind of moment.

That left direct resin and a ceramic inlay, and the deciding factor was the patient’s main complaint: impaction. A direct resin filling builds the contact inside the mouth with a matrix band, which makes it hard to control the contact tightness and the height of the marginal ridge numerically. With a ceramic inlay, the position and tightness of the contact with the neighboring tooth are set in the design software at the micrometer level, and checked and adjusted again at try-in after milling. That is why Seongmo Dental Clinic chose a same-day inlay for a case where the contact point had to be rebuilt precisely.

The material was lithium disilicate glass ceramic (IPS e.max CAD). According to the manufacturer (Ivoclar), it is easy to mill at 130 MPa in its blue pre-crystallized state and reaches a flexural strength of about 360–530 MPa (depending on the test method) and a fracture toughness of about 2.11 MPa·m¹ᐟ² after crystallization firing. Survival of ceramic inlays and onlays has been reported at 92–95% at 5 years and 91% at 10 years, with fracture or chipping (4%), endodontic complications (3%) and secondary caries (1%) as the main reasons for failure (Morimoto et al., 2016 — meta-analysis of 14 studies).

Two things were checked before committing to an inlay. First, how close the caries was to the pulp (the nerve) — the distance between the caries and the pulp was checked on the pre-treatment periapical X-ray, and after caries removal the prepared surface was inspected directly for pulp exposure or remaining caries. Second, whether enough cusp remained to withstand chewing forces — if the remaining walls had been thin, we would have switched to an onlay. Both were satisfied, so we proceeded with an inlay.

How did the same-day inlay proceed at our clinic in Seongbuk-gu?

A same-day inlay completes scanning, design, milling, firing and bonding in-house in a single visit.

1. Diagnosis — The distal proximal caries on #16 was confirmed on the panoramic and periapical X-rays, and the contact with the neighboring molar (#17) was checked with floss.
2. Anesthesia — A posterior superior alveolar nerve block (2% lidocaine with 1:100,000 epinephrine). The computer-controlled anesthesia system at Seongmo Dental Clinic (i-JECT) is designed to keep the injection rate constant to reduce injection pain.
3. Caries removal — The cusps were kept; the caries and the remnants of the old restoration were removed, and the prepared surface was inspected for remaining caries and pulp exposure.
4. 3D intraoral scan — Without impression material, the prepared surface, the neighboring teeth and the opposing teeth were captured digitally.
5. Design (CAD) — The director set the position and tightness of the contact with the neighboring molar (#17), the height of the marginal ridge and the shape of the occlusal surface as micrometer-level values.
6. Milling — The in-house Primemill milled a lithium disilicate block (A2). By our own measurement, milling one crown takes about 5 minutes.
7. Firing — Crystallization and glaze firing in the SpeedFire takes the 130 MPa blue block to its final strength (about 360–530 MPa).
8. Try-in and contact adjustment — The contact tightness was checked with floss and contact-marking film. If it is too tight, the contact surface is polished at the micrometer level; if it is too loose, the design value is increased and the inlay is milled again. The margins were checked with an explorer.
9. Bonding — The inner surface of the ceramic was treated with Monobond Etch & Prime (a method that reduces the conventional nine steps to four, without hydrofluoric acid), the inlay was bonded with resin cement, excess cement was removed, the bite was adjusted and the surface polished, and a periapical X-ray was taken to check the proximal margin and for any remaining excess cement.

After bonding, the patient tried the floss and said, “Now I can feel it catch here — until now it just went straight through.” Everything from the examination to bonding was finished in one morning session, and the treatment itself was completed the same day. Whether impaction after meals has actually decreased will be checked again by floss resistance at the regular check-up.

What changes about the contact point when the inlay is made in-house at Seongmo Dental Clinic?

Contact adjustment is the process of setting where, and how tightly, a new restoration touches the neighboring tooth at the try-in stage.

An inlay made by an outside laboratory usually takes one to two weeks to come back after the impression, and the patient wears a temporary filling in the meantime. If the finished inlay’s contact is too tight it can be ground down in the treatment room, but if it is too loose, ceramic cannot be added — it has to be remade, and that means another visit. This process is standard and does not mean the result is poor. But for a patient whose main complaint is impaction, the moment to check and correct the contact point should be now, not at the next visit.

The same-day inlay at Seongmo Dental Clinic, next to Sungshin Women’s University Station, never leaves the clinic. The contact tightness is specified as a micrometer-level value at the design stage, and the milled inlay is tried in and the contact checked by floss resistance. Contacts are classified by the resistance felt as floss passes through — tight, loose or open (Hancock et al., 1980) — and the goal is a tight contact where the floss catches slightly as it passes but does not shred. If it is too tight, it is polished on the spot at the micrometer level; if too loose, the design value is raised and the inlay is milled again (about 5 minutes for one crown). The margins are checked with an explorer, keeping in mind the clinically accepted marginal gap of 120 μm or less (McLean & von Fraunhofer, 1971 — observation of more than 1,000 crowns). A workflow in which the contact adjustment is completed within the same day can help reduce food impaction.

For a patient like this one, who finds it hard to take time off on weekdays, the meaning of a same-day inlay is “once.” He came for a first visit on a Saturday morning, and the examination, anesthesia, preparation, scan, milling, firing and bonding were all finished in the same chair, with no period spent on a temporary filling.

When is a same-day ceramic inlay suitable, and when is another option better?

An inlay is indicated for moderate caries confined to the proximal and occlusal surfaces, with sound cusps.

Suitable cases

• A molar with proximal (Class II) caries in which the marginal ridge has collapsed but the cusps remain
• Cases where food impaction is the main complaint and the contact point and marginal ridge need to be controlled numerically at the design stage
• Old fillings that need replacement because of repeated loss, discoloration or secondary caries
• Working people, students and patients living far away who need to keep the number of visits down

When another option is recommended

• Caries that has reached the pulp, or spontaneous pain → root canal treatment followed by restoration (see the plasma root canal and same-day crown case)
• Thin cusps or a crack → onlay or overlay crown (see the cracked molar, pulpotomy and same-day overlay crown case)
• A space created by gum recession or tooth movement → periodontal treatment or an orthodontic assessment first
• Severe grinding or clenching → material and thickness reconsidered, and a night guard considered alongside

❓ Frequently Asked Questions

This clinical case was written as of August 2026.