hello there....bitewing radiograph is actually taken to rule out any proximal caries...Your concern is about the white growth you see below the gumline. That could be a fibroma
that results because of any local injury
or irritation to that site consistently. Usually fibroma is firm in consistency and hardly enlarges in size. That requires excision. For the purpose of differential diagnosis the other lesions could be an epulis
as a result of carious tooth. Any of these lesions have to be treated. Consult an expert for further diagnosis and management.