An 11-year-old girl complains about gingival haemorrhage during tooth brushing and eating. She has been suffering from this for a year. Gum of both upper and lower jaws is edematic and congestively hyperemic. Hygienic state of oral cavity is unsatisfactory. Bite is edge-to-edge. Roentgenological examination of periodontium revealed no pathological changes. What is the provisional diagnosis?