Since 1992, chronic gastritis lesions are classified according to the Sydney system. Metaplasia
Mucous gland metaplasia, the reversible replacement of differentiated cells, occurs in the setting of severe damage of the gastric glands, which then waste away (atrophic gastritis) and are progressively replaced by mucous glands. Gastric ulcers may develop; it is unclear if they are the causes or the consequences. Intestinal metaplasia typically begins in response to chronic mucosal injury in the antrum and may extend to the body. Gastric mucosa cells change to resemble intestinal mucosa and may even assume absorptive characteristics. Intestinal metaplasia is classified histologically as complete or incomplete. With complete metaplasia, gastric mucosa is completely transformed into small-bowel mucosa, both histologically and functionally, with the ability to absorb nutrients and secrete peptides. In incomplete metaplasia, the epithelium assumes a histologic appearance closer to that of the large intestine and frequently exhibits dysplasia. Diagnosis
Often, a diagnosis can be made based on  patients description of their symptoms. Other methods which may be used to verify gastritis include:

Blood tests:
Blood cell count
Presence of H. pylori
Liver, kidney, gallbladder, or pancreas functions
Urinalysis
Stool sample, to look for blood in the stool
X-rays
Endoscopy, to check for stomach lining inflammation and mucous erosion
Stomach biopsy, to test for gastritis and other conditionsThe OLGA staging frame of chronic gastritis on histopathology. Atrophy is scored as the percentage of atrophic glands and scored on a four-tiered scale. No atrophy (0%) = score 0; mild atrophy (1–30%) = score 1; moderate atrophy (31–60%) = score 2; 9 severe atrophy (>60%) = score 3.
Fluorosis may refer to:

Dental fluorosis, a disturbance of dental enamel caused by excessive exposure to high concentrations of fluoride during tooth development. Skeletal fluorosis, a bone disease caused by excessive accumulation of fluoride in the bones
Fluoride toxicity, elevated levels of the fluoride ion in the body