Siwak is not solely a private matter: oral cleanliness also makes interaction more comfortable for others. Speaking, studying, praying, and attending gatherings with a clean mouth show consideration.
Example 1: A person speaks with others at close range. Attention to oral hygiene benefits those nearby.
Example 2: Someone practises daily cleaning while remembering the desire to please Allah. Both practical and devotional purposes are present.
The report speaks specifically about siwak and also shows the value of cleanliness more generally. It does not attempt to describe every medical method of oral care.