Anatomy of the Maxillary Sinus

MAXILLARY SINUS DISEASES AND TREATMENT Anatomy of the Maxillary Sinus The maxillary sinus is the largest of the paranasal sinuses and is located within the upper jaw (maxilla). The roots of the 1st and 2nd maxillary molar teeth, in particular, create conical protrusions at the base of the sinus. Maxillary sinuses are either absent or very small at birth. The development of the sinuses plays an important role in changing the size and shape of the face during infancy and childhood. They gradually develop until puberty and are fully developed by the age of 25. After puberty, when they complete their development and are filled with air, they add resonance to the voice. Nerve Innervation The maxillary sinuses are innervated by a wide network of nerves. Innervation is through the posterior-superior alveolar branch of the maxillary nerve, a branch of the N. trigeminus. Blood supply to the maxillary sinus is provided by the infraorbital and posterior-superior alveolar branches of the maxillary artery. The branches of the anterior-superior alveolar artery are also included. Lymphatic drainage is to the retropharyngeal and submandibular lymph nodes. Because the N. alveolaris superior innervates both the maxillary posterior teeth and the mucosa of the maxillary sinus, the pain caused by sinusitis can be confused with toothache, and the reverse can also occur. The maxillary sinus is the largest of the paranasal sinuses and the most susceptible to intraoral complications of dental origin. FUNCTIONS: ● ● ● By humidifying and warming the inhaled air, it creates conditioned respiratory air thanks to its wide mucosal surface. It is thought to reduce the weight of the head. It is believed to play a role in the resonance of the voice. A supporting finding is the voice changes seen in people in cold weather. Walls of the Maxillary Sinus: ● Medial Wall (Nasal Wall): Separates the sinus from the nasal cavity and is the region where the osteomeatal complex is located. The drainage hole of the sinus, the ostium, is located here. ●​ Lateral Wall: Forms the outer part of the maxillary sinus and is adjacent to the roots of the maxillary molar teeth. ●​ Superior Wall (Orbital Floor): Forms the floor of the eye socket and is where the infraorbital nerve runs. ●​ Inferior Wall (Alveolar Process): Related to the roots of the upper jaw teeth. The roots of the premolar and molar teeth may be very close to or protrude into the sinus floor. ●​ Posterior Wall: Located near the pterygopalatine fossa, where the posterior superior alveolar nerves and vessels are located. If a tooth is extracted, the thin bone lamella surrounding the tooth root may come out with the tooth root, resulting in the alveolus of the tooth merging with the maxillary sinus. This can cause the infection in the tooth root to spread to the maxillary sinus. Therefore, it is important to remember this danger during tooth extraction. Radiology of the Maxillary Sinus The maxillary sinus can be examined radiologically using periapical, occlusal, and panoramic films, as well as special sinus films known as Water’s and Caldwell position graphs, and also lateral films, CT, MRI, angiography, and endoscopy methods. Periapical films provide clearer images of details compared to other films but have the disadvantage of showing only the floor and lower parts of the sinus. Occlusal graphs also show a limited area, displaying the anterior region of the maxillary sinus. Additionally, these films do not allow for comparison of the right and left sides. Panoramic films are more advantageous for viewing the details of the maxillary sinus and evaluating both sides together. Cysts near the sinus floor and tumors inside the sinus can be seen with these films. Periapical, occlusal, and panoramic films are very useful for locating a foreign object that has entered the sinus. In the diagnosis of sinus diseases, panoramic and Water’s graphs are often evaluated together to complement each other. Caldwell position films, like Water’s films, are posterior-anterior head projections but are a modified version. In Caldwell films, the beam is parallel to the sinus floor and perpendicular to the film, making small pathological masses in the posterior part of the sinus floor clearer than in Water’s films. Additionally, the appearance of the sinus roof and middle wall is very clear in Caldwell films, making it easy to distinguish between diseased and healthy sinuses. MAXILLARY SINUS DISEASES Sinus infections are commonly referred to as sinusitis. Sinusitis occurs most frequently in the maxillary sinus, followed by the ethmoid, frontal, and sphenoid sinuses in descending order of frequency. When sinusitis occurs in most or all of the paranasal sinuses, this condition is called pansinusitis. Maxillary Sinus Diseases ●​ ●​ ●​ ●​ ●​ ●​ ●​ ●​ ●​ Non-Specific Infections Specific Infections Mucus Retention Cyst Granulomatous Diseases Tumors Local hyperplasia originating from odontogenic infection Foreign Bodies Oroantral Fistula Fractures Factors in the etiology of maxillary sinus disease include: ●​ ●​ ●​ ●​ ●​ ●​ ●​ Upper respiratory tract infections Anatomical and physiological abnormalities that will disrupt free drainage from the sinus Odontogenic infections or the escape of an infected root into the sinus during extraction Reduced or impaired cilia activity due to smoking and air pollution Vigorous swimming or diving Allergic reasons Specific factors (fungus, syphilis, leprosy, etc.) The origins of odontogenic infections of maxillary sinusitis are acute and chronic periapical infections. Infections and sinusitis can also result from trauma to the teeth, surgical interventions in the posterior maxilla, tooth extractions, alveolectomy, tuber trimming, and other procedures that can create a connection between the oral cavity and the sinus. Sinusitis can present acutely, chronically, or in a transitional phase between the two known as subacute. Acute Sinusitis Acute sinusitis is almost always of nasal origin, rarely dental origin. To diagnose it, learning subjective symptoms, performing rhinoscopy, transillumination, and finally simple radiographs are sufficient. The condition usually starts three to four days after the onset of severe cold or flu symptoms, and severe facial pain appears. This situation can also be the awakening of a previously existing chronic sinusitis. The facial pain is very severe and localized in the sinus area. Sometimes this pain radiates upwards and is felt as a severe headache, which can also suggest frontal sinusitis or frontal sinus abscess. Sometimes the pain radiates downwards, giving the impression of tooth infection, but the pain is not localized to a single tooth but the entire arch. A second symptom of acute sinusitis is purulent nasal discharge. In rhinogenic sinusitis, this discharge does not have a bad odor, but in odontogenic sinusitis, the discharge has a foul odor. Rhinogenic sinusitis, being more of a mucosal disease, does not exteriorize on the face. Maxillary sinusitis can occur at any age. It often follows allergic rhinitis and viral infections of the upper respiratory tract. Chronic allergies, the presence of foreign bodies, and nasal septum deviations are predisposing factors. Chronic Sinusitis Chronic sinusitis develops due to the continuation of predisposing factors, following acute sinusitis, and as a result of low-grade and recurrent bacterial and fungal infections, and less commonly from odontogenic infection. Microbiology of Sinus Infections Maxillary sinus infections can be caused by aerobic, anaerobic, or mixed bacteria. In a normal healthy sinus, there is a small bacterial community composed mainly of aerobic streptococci and anaerobic gram-positive cocci. These bacteria belong to the Bacteroides and Fusobacterium families. In cases of nonodontogenic sinusitis, the bacteria in question are primarily Streptococcus Pneumoniae, Haemophilus Influenzae, Staphylococcus Aureus, and Beta Streptococci. Maxillary Sinus Openings Extraction of posterior upper teeth, maxillary sinusitis, and oroantral fistula can lead to oro-maxillary sinus openings (oroantral openings). An oroantral opening can be defined as an unnatural opening between the oral cavity and the maxillary sinus. The anatomical proximity of the roots of the posterior upper teeth to the maxillary sinus is the most common cause of this opening. In addition, cysts, tumors, trauma, and other simple surgeries in the region can also be considered etiological factors. If the oroantral opening that occurs as a result of these etiological factors is 1-3 mm in diameter, it often heals without intervention. In such cases, it is sufficient to provide the patient with antibiotic therapy. However, if the opening is larger than 4-5 mm in diameter, surgical intervention is required. Techniques for Surgical Closure of Oroantral Openings Many techniques have been proposed for closing an OAF. These techniques can be categorized into three main types: 1.​ Local Flap Applications 2.​ Distant Flap Applications 3.​ Graft Applications