is recommended. On a CT scan, acute sinus secretions have a radiodensity of 10 to 25 Hounsfield units (HU), but in a more chronic state they become more viscous, with a radiodensity of 30 to 60 HU. Nasal endoscopy and clinical symptoms are also used to make a positive diagnosis. A tissue sample for histology and cultures can also be collected and tested. Nasal endoscopy involves inserting a flexible fiber-optic tube with a light and camera at its tip into the nose to examine the nasal passages and sinuses. Sinus infections, if they result in tooth pain, usually present with pain involving more than one of the upper teeth, whereas a toothache usually involves a single tooth. Dental examination and appropriate radiography aid in ruling out pain arises from a tooth. Treatment Recommended treatments for most cases of sinusitis include rest and drinking enough water to thin the mucus. Antibiotics are not recommended for most cases. Breathing low-temperature steam such as from a hot shower or gargling can relieve symptoms. There is tentative evidence for nasal irrigation in acute sinusitis, for example during upper respiratory infections. Decongestant nasal sprays containing oxymetazoline may provide relief, but these medications should not be used for more than the recommended period. Longer use may cause rebound sinusitis. It is unclear if nasal irrigation, antihistamines, or decongestants work in children with acute sinusitis. There is no clear evidence that plant extracts such as Cyclamen europaeum are effective as an intranasal wash to treat acute sinusitis. Evidence is inconclusive on whether anti-fungal treatments improve symptoms or quality of life. Antibiotics Most sinusitis cases are caused by viruses and resolve without antibiotics. However, if symptoms do not resolve within 10 days, either amoxicillin or amoxicillin/clavulanate are reasonable antibiotics for first treatment with amoxicillin/clavulanate being slighlty superior to amoxicillin alone but with more side effects. A 2018 Cochrane review, however, found no evidence that people with symptoms lasting seven days or more before consulting their physician are more likely to have bacterial sinusitis as one study found that about 80% of patients have symptoms lasting more than 7 days and another about 70%. Antibiotics are specifically not recommended in those with mild / moderate disease during the first week of infection due to risk of adverse effects, antibiotic resistance, and cost. Fluoroquinolones, and a newer macrolide antibiotic such as clarithromycin or a tetracycline like doxycycline, are used in