Restorative & Materials · patient case question
What is the cause of the open contact?
Patient case: Food impaction between two restored premolars
Patient: Adult who recently received Class II restorations
Chief complaint: “Food keeps getting stuck between my back teeth.”
Background: Mesial and distal restorations were recently placed in the premolar region.
Current findings: Bitewing radiograph shows an open contact between teeth #20 and #21.
Show answer and explanation
Correct answer: A. Poor contour and adaptation of the matrix band
- A. CORRECT. The proximal contour and contact of a Class II restoration are determined entirely by the matrix. If the band is not properly contoured, wedged and burnished against the adjacent tooth, the restoration is built flat and the contact is left open or deficient. This is the commonest technical cause of post-restorative food impaction.
- B. Band thickness contributes, and thinner sectional bands are preferred precisely for this reason, but the governing failure is contour and adaptation.
- C. 'Self-cleaning' is not a real explanation for an open contact; food impaction is pathological and causes papillary inflammation and interproximal caries.
- D. Over-condensation is a concern for amalgam marginal ridge fracture, not for open contacts.
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