# Oroantral Communication > Oroantral communication and fistula for BDS Oral Surgery: diagnosis, size-based closure with buccal and palatal flaps, sinus precautions and Rehrmann flap. - Canonical URL: https://prepelephant.com/topics/bds/oral-surgery/oroantral-communication - Exam / course: BDS · Subject: Oral Surgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Oroantral Communication", PrepElephant, https://prepelephant.com/topics/bds/oral-surgery/oroantral-communication ## Direct answer An oroantral communication is a patent tract between the oral cavity and the maxillary sinus, most often created by extracting an upper molar or premolar whose roots project into the antrum. A communication present for weeks becomes lined by epithelium and is then an oroantral fistula, which will not close spontaneously. Diagnosis rests on the nose-blow test and passage of fluids or air, and management is size-based: defects under about 2 mm heal by secondary intention with sinus precautions, 2-5 mm defects are closed with a figure-of-eight or purse-string suture, and anything larger needs a flap — classically the Rehrmann buccal advancement flap or a palatal pedicle flap. ## What you must remember - **Cause and risk roots:** upper first molar roots lie closest to the sinus floor; multi-rooted teeth, periapical lesions that erode the cortex, and heavy extractions in the elderly pneumatised sinus are the classic settings. - **Bedside tests:** nose-blow test (bubbles escape the socket), suction-aspiration of a drop of saline into the socket, and the patient's report of liquid entering the nose while rinsing. - **Size ladder:** under 2 mm — sinus precautions and observation; 2-5 mm — figure-of-eight or purse-string suture over the socket; over 5 mm or persisting — flap closure. - **Flap options:** Rehrmann buccal advancement flap (with releasing periosteal incision; buccinator muscle and vessel preserve blood supply) or a palatal rotation-advancement flap pedicled on the greater palatine artery. - **Sinus precautions:** no nose blowing or straw use for 10-14 days, sneeze with the mouth open, decongestant nasal drops, and antibiotics; these apply after every closure attempt. - **Fistula, not communication:** an epithelially lined tract beyond about two weeks needs freshening of the edges before closure; suturing epithelium to epithelium fails. - **Persistent antral pathology:** a diseased, obstructed sinus will defeat any flap; treat maxillary sinusitis energetically, and reserve Caldwell-Luc or endoscopic sinus surgery for refractory cases. ## Closing a fresh 8 millimetre defect step by step Imagine a 52-year-old whose upper right first molar socket communicates briskly with the antrum — the socket bubbles on nose blowing, and a fine probe passes without resistance. The socket is gently curetted of the granulation tissue, irrigated, and inspected; the defect measures about 8 mm, so a suture alone will strangle. Local anaesthesia is infiltrated buccally and palatally. A Rehrmann flap is raised: two diverging vertical incisions extend from the socket edges into the buccal sulcus, a full thickness mucoperiosteal flap is reflected, and a horizontal releasing incision through the periosteum at the flap base — deep enough to release, superficial to the buccinator — lets the flap slide palatally without tension. The palatal edge of the defect is freshened until bleeding bone and mucosa appear, the flap is carried over the socket, and 3-0 silk mattress sutures anchor it to the palatal mucosa. The periosteal release lengthens the vestibule slightly, which is the accepted trade-off. Had the defect been wide and anterior, or the buccal tissue scarred from previous surgery, a palatal pedicle flap based on the greater palatine artery would be rotated from the homolateral palate instead, its exposed donor site left to granulate under a pack. ## How the exam frames it The examiner's script has three stations. First, the definitions: communication is a hole, fistula is an epithelially lined hole — and the number they want is roughly two to three weeks for epithelialisation, which is why a neglected defect cannot simply be stitched. Second, the tactical question: why the periosteal releasing incision in a Rehrmann flap, and which structure must not be cut — the answer is tension-free mobilisation while preserving the buccinator-based blood supply. Third, the trap: a fistula that recurs after two competent flaps usually means antral disease, not flap failure, so request an OPG or CT for sinusitis, polyps or a retained root tip before re-operating. Indian viva boards also expect sinus precautions recited verbatim, since they are the cheapest marks on the page. ## Frequently asked questions ### Which tooth extraction most commonly opens an oroantral communication? The upper first molar, whose roots lie closest to the maxillary sinus floor, followed by other upper molars and premolars. ### How is an oroantral communication diagnosed at the chairside? A positive nose-blow test with escape of air bubbles from the socket, suction of saline into the wound, or the patient reporting fluid regurgitating into the nose. ### When can a communication be left to heal without surgery? Defects smaller than about 2 mm close spontaneously with strict sinus precautions, decongestants and antibiotics for 10-14 days. ### What is a Rehrmann flap? A buccal advancement flap released by a periosteal incision so it slides over the socket without tension, its blood supply preserved from the buccinator bed. ### Why must an oroantral fistula be treated differently from a fresh communication? The tract is epithelially lined after about two to three weeks, so the lining must be excised and the edges freshened before any flap will take.