Persistent "Marginal Gingivitis" can be caused by a few factors, the first being tarter below the gum line. This hard material is a collector of dental plaque which causes inflammation. I also note your wisdom tooth is not fully erupted. This may also be a factor. Other factors could include your "bite" or occlusion, habits, diet, or some systemic conditions. I would return to the dentist for a further evaluation. Your dentist should be able to address this, or refer you to one able to make a diagnosis and treatment plan.

Fredric K. Weiss