In the maxilla, these teeth are often displaced into the maxillary sinus. Classic symptoms of sinus disease such as headache, facial pain, purulent nasal discharge or nasolacrimal obstruction may occur when maxillary sinus is involved. According to a study, 45.7 percent of dentigerous cysts involved mandibular third molar. On the other hand, only 2.7 percent of dentigerous cysts involved the maxillary premolar. Mourshed stated that the incidence of dentigerous cyst has been reported as 1.44 in every 100 unerupted teeth, so dentigerous cysts involving the premolars are rare. Dentigerous cysts most commonly occur in the 2nd and 3rd decades of life. Males have been reported to be more prevalent than females with a ratio of 1.8:1. These cysts can also be found in young children and adolescents. The age of presentation of these cysts range from 3 years to 57 years with a mean of 22.5 years. These cysts are commonly single lesions. Bilateral and multiple dentigerous cysts are very rare although they have been reported. Bilateral or multiple dentigerous cysts have been reported in Maroteaux-Lamy syndrome, cleidocranial dysplasia and Gardners syndrome In the absence of these syndromes, the occurrence of multiple dentigerous cysts is rare. Sometimes multiple dentigerous cysts are suggested to be induced by prescribed drugs. The combined effect of cyclosporine and a calcium channel blocker is reported to cause bilateral dentigerous cyst
Dentigerous cyst is potentially capable of becoming an aggressive lesion.
He theorized that the reduction in available natural light during winter was the cause. Rosenthal and his colleagues then documented the phenomenon of SAD in a placebo-controlled study utilizing light therapy. A paper based on this research was published in 1984. Although Rosenthals ideas were initially greeted with skepticism, SAD has become well recognized, and his 1993 book, Winter Blues has become the standard introduction to the subject.Research on SAD in the United States began in 1979, when Herb Kern, a research engineer, had also noticed that he felt depressed during the winter months. Kern suspected that scarcer light in winter was the cause, and discussed the idea with scientists at the NIMH who were working on bodily rhythms. They were intrigued, and responded by devising a lightbox to treat Kerns depression. Kern felt much better within a few days of treatments, as did other patients treated in the same way. Signs and symptoms
SAD is a type of major depressive disorder, and those with the condition may exhibit any of the associated symptoms, such as feelings of hopelessness and worthlessness, thoughts of suicide, loss of interest in activities, withdrawal from social interaction, sleep and appetite problems, difficulty with concentrating and making decisions, decreased libido, a lack of energy, or agitation. Symptoms of winter SAD often include falling asleep earlier or in less than 5 minutes in the evening, oversleeping or difficulty waking up in the morning, nausea, and a tendency to overeat, often with a craving for carbohydrates, which leads to weight gain.