During obturation, endodontic sealer and gutta-percha are extruded beyond the apex and enter the maxillary sinus. Which of the following teeth is the MOST likely source?

Correct answer: C. Maxillary second premolar

• A. The MAXILLARY CANINE has the longest root in the mouth, but it is positioned anteriorly beneath the canine eminence and its apex relates to the nasal cavity and canine fossa — not the maxillary sinus.
• B. The MAXILLARY CENTRAL INCISOR apex relates to the floor of the nasal cavity and the incisive canal, well anterior to the sinus.
• C. CORRECT. Of the options given, the MAXILLARY SECOND PREMOLAR is the only tooth whose apex lies in close relation to the floor of the maxillary sinus. The sinus floor typically extends anteriorly to about the premolar region, and in pneumatised sinuses the apices of the second premolar and the molars may be separated from the sinus by a paper-thin cortical plate or by nothing but sinus mucosa. Material extruded from these apices passes directly into the antrum.
• D. The MAXILLARY LATERAL INCISOR apex lies in the anterior maxilla and curves distopalatally. It is nowhere near the sinus; its palatal proximity is the relevant anatomical concern.

Note: Overall, the MAXILLARY MOLARS — particularly the second molar's palatal and mesiobuccal roots — are the teeth most intimately related to the sinus floor and the most common source of both sinus perforation and odontogenic sinusitis. The second premolar is simply the most posterior of the options offered here. Management of material displaced into the sinus: obtain a CBCT or Waters view, prescribe decongestants and sinus precautions, and refer for endoscopic retrieval if the fragment is large, symptomatic, or persists — retained foreign material is a nidus for chronic sinusitis and aspergillosis.