This Topic Review mainly covers dental plaque-associated gingivitis (subsequently referred to as 'gingivitis') and periodontitis. The treatment of acute necrotizing ulcerative gingivitis is briefly reviewed. The management issues covered in this guideline are as follows: · What assessment do I need to make? · How do I manage plaque-associated gingivitis and periodontitis? · How do I manage acute nectrotizing ulcerative gingivitis? · When should I refer? · What advice should I give on oral hygiene? Medications discussed include chlorhexidine, metronidazole and amoxicillin.