odontogenic sinusitis

Introduction

infection of the sinuses is common and often becomes chronic
most commonly, bilateral sinusitis is a complication of upper respiratory tract infections - see sinusitis
chronic unilateral maxillary sinusitis is very suggestive of an odontogenic sinusitis
involvement of the ostiomeatal unit may result in extension to adjacent paranasal sinuses with reported rates of extramaxillary extension ranging from 27% to 60% and up to 20% have bilateral involvement ¹⁾
incidental bilateral sinusitis on CT brains down for other reasons is generally incidental and should not automatically be assumed to be the cause of the patient's symptoms

see 2024: Expert consensus on odontogenic maxillary sinusitis multi-disciplinary treatment
“as individuals age, the maxillary alveolar bone diminishes in thickness, resulting in a delicate mucoperiosteal layer that forms a barrier between the maxillary sinus and the oral cavity, known as the Schneiderian membrane”
“some of the dental nerves, lymphatics and vascular plexus that supply the dental roots are located directly under the maxillary sinus mucosa”
“when the gasification of the sinuses is obvious, the third molar, premolar and canine may project into the maxillary sinus and be separated only by thin bone or mucosa, forming an alveolar recess”
“in normal conditions, the thick cortical of maxillary sinus floor can prevent inflammation of the dental roots from entering the maxillary sinus”
“when there is periapical lesions or severe periodontitis in upper dentition, the maxillary sinus mucosa has a tendency to thicken and the inflammatory mediators can even spread into the sinus cavity through the blood vessels, lymphatics and even muscle space”
the mucosal swelling may then lead to obstruction of the ostiomeatal complex (OMC) which is superior aspect of the medial wall and this then prevents drainage and results in sinusitis
in addition, there are microbiome and individual immune response characteristics at play

most common in 40-60yr olds
accounts for ~10% of cases of maxillary sinusitis (50-75% of cases of unilateral sinusitis)

~2/3rds result from dental procedures including dental implants
most other cases result from infection of the maxillary dentition (esp. molars (1st > 2nd > 3rd) and pre-molar) such as apical abscess or periodontitis
other causes include:
- dental trauma
- maxillary bone trauma
- odontogenic cysts
- neoplasms
- other inflammatory processes

tender maxilla
foul smell, unilateral head/facial pain tend to differentiate it from non-odontogenic maxillary sinusitis
diagnosis is usually made on CT scan or perhaps OPG showing BOTH sinus involvement AND a dental cause
- Cone beam computed tomography (CBCT) has higher sensitivity than plain CT ²⁾
- CT evidence for maxillary sinusitis:
  - thickened mucosa of sinus > 2mm, or,
  - air-fluid level within sinus, or,
  - opacification of sinus
- CT evidence of ipsilateral upper dental causative issue:
  - periapical lesions, or,
  - severe alveolar bone loss (absorption to2/3 of the root or more), or
  - a FB in the antrum, or
  - presence of an oroantral fistula

the infection can spread from the maxillary sinus to the facial soft tissues - periorbital or intraorbital, and even into the cavernous sinus or intracranial region, thus leading to facial cellulitis, Periorbital and orbital cellulitis, orbital abscess and cavernous sinus thrombophlebitis or intracranial infection

broad spectrum antibiotics such as Augmentin Due Forte (adults)
- bacteriology is different to usual sinusitis and commonly mixed growth including Peptostreptococcus, Prevotella, and Fusobacterium and thus antibiotic Rx needs to be broad spectrum including anaerobic cover
dental assessment for possible root canal Rx, etc as indicated
endoscopic sinus surgery may be required for patients who fail initial medical management and dental treatment

¹⁾

²⁾