The maxillary sinus is not only the largest of the paranasal sinuses but also one of the most significant anatomical structures in oral and maxillofacial practice.
Located in the body of the maxilla, just above the posterior teeth and beneath the orbital floor, its close relationship with the upper dentition makes it a key consideration in various dental specialties—from endodontics and oral surgery to prosthodontics and implantology.
Over the past decade, advances in cone-beam computed tomography (CBCT), surgical navigation, and biomaterials have enabled more predictable interventions involving the sinus.
However, these procedures carry inherent risks due to anatomical variations such as septa, membrane thickness, and maxillary sinus pneumatization, especially after tooth loss.
Understanding the morphology and physiological functions of the maxillary sinus is critical for:
✔ Reducing iatrogenic complications during implant placement,
✔ Planning sinus lift surgeries,
✔ Preventing oroantral communications,
✔ Managing odontogenic sinusitis effectively.
This article provides an updated overview of the maxillary sinus anatomy and its direct implications in oral rehabilitation based on recent studies published in the last 7 years.
Anatomical Overview of the Maxillary Sinus
✔ Shape and Dimensions
Pyramid-shaped and varying in volume between 15–30 mL, the maxillary sinus continues to develop postnatally and reaches full size by adulthood. Its dimensions are dynamic and can change due to age, gender, and dental status.
✔ Anatomical Boundaries
- Superior wall: orbital floor
- Inferior wall: alveolar ridge, often in close proximity to molar roots
- Medial wall: lateral wall of the nasal cavity
- Posterior wall: adjacent to the infratemporal fossa
✔ Mucosa and Membrane
The Schneiderian membrane lines the sinus—typically 0.3–0.8 mm thick. Its integrity is crucial during surgical access to the sinus.
✔ Anatomical Variants
- Underwood's septa (bony partitions) occur in ~30% of cases, altering sinus morphology and complicating sinus elevation procedures.
- Accessory ostia and pneumatization patterns must be assessed preoperatively via CBCT.
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Clinical Importance in Dentistry and Oral Rehabilitation
1. Implant Planning and Sinus Lift Surgery
✔ Indication: Insufficient bone height in the posterior maxilla due to sinus pneumatization or alveolar ridge resorption.
✔ Surgical Approaches:
- Lateral window technique
- Crestal (osteotome) technique
✔ Success Rates: Long-term studies report survival rates over 90% when proper biomaterials and techniques are used.
Preoperative CBCT is essential to evaluate:
✔ Height and width of residual alveolar bone
✔ Presence of septa or sinus pathologies
✔ Schneiderian membrane thickness
2. Tooth Extractions and Sinus Pneumatization
After extraction of molars and premolars, the sinus tends to expand inferiorly (pneumatization), reducing the vertical bone dimension. This is more pronounced in elderly patients and can hinder prosthetic or implant-supported rehabilitation.
3. Complications Related to the Maxillary Sinus
✔ Membrane perforation: Occurs in 13–30% of sinus lifts. Proper instrumentation and preoperative imaging reduce this risk.
✔ Implant displacement into sinus: May require endoscopic removal using minimally invasive sinus surgery (MESS) techniques.
✔ Oroantral communications (OACs): Must be identified and repaired promptly to prevent chronic sinusitis.
4. Odontogenic Sinusitis (OS)
Up to 40% of chronic maxillary sinusitis cases have a dental origin. Common causes include:
✔ Untreated periapical lesions
✔ Periodontal infections
✔ Foreign bodies (e.g., root fragments or displaced implants)
A multidisciplinary approach involving dentists, oral surgeons, and ENT specialists is crucial for diagnosis and treatment.
Conclusion
✔ The maxillary sinus is a multifunctional anatomical space whose structure and physiology directly influence dental diagnostics and treatment planning.
✔ Mastery of its anatomy—including septa, ostia, and mucosal thickness—is essential for implant success and surgical safety.
✔ With the rise of digital imaging (CBCT) and biomaterial innovation, sinus-related procedures continue to improve in predictability and patient outcomes.
✔ Odontogenic sinusitis remains a key challenge, requiring joint management across medical and dental disciplines.
📚 Scientific References
- Dentomaxillofacial Radiology (2019) 48, 20190205. The maxillary sinus: physiology, development and imaging anatomy.
- Anatomy & Cell Biology 2019; 52(1): 17-24. Clinical anatomy of the maxillary sinus: application to sinus floor augmentation.
- Rev. ORL, 2023, 14, 1, 35-54. MAXILLARY SINUS PATHOLOGY AND ITS RELATIONSHIP WITH PATHOLOGY AND DENTAL TREATMENTS. SYSTEMATIC REVIEW.
