Perhaps you should try some spelling variations:
decrease periodontal » increased periodontal (Expand search), disease periodontal (Expand search), diseases periodontal (Expand search)
periodontal effect » periodontal effects (Expand search), periodontais effect (Expand search), periodontal defect (Expand search)
decrease faster » decrease after (Expand search), decrease further (Expand search), decreased after (Expand search)
faster decrease » rate decrease (Expand search)
decrease loss » decrease costs (Expand search), decrease low (Expand search), decrease blood (Expand search)
loss decrease » loss decreases (Expand search), cross decreased (Expand search), to decrease (Expand search)
decrease the » decreases the (Expand search), decrease in (Expand search), decrease of (Expand search)
the decrease » to decrease (Expand search), and decrease (Expand search)

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease the decrease faster decrease ) OR ( decrease loss decrease periodontal effect ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease the decrease faster decrease ) OR ( decrease loss decrease periodontal effect ))*.