Answered by Shaykh Faraz Rabbani
Would one gain the same reward as using a toothbrush to clean ones teeth as opposed to using a siwak irrespective of the cleaning ability of the toothbrush? Is the sunna still being completed?, as what is intended is the cleaning of the teeth??
Walaikum assalam,
That which is a confirmed sunna in wudu is “istiyak,” or brushing one’s teeth. [Ibn Abidin’s Radd al-Muhtar, Ibn Nujaym’s Bahr al-Ra’iq]
This sunna is achieved by that which cleans one’s teeth, and would include modern toothbrushes. However, the optimal reward, and maximal benefit lies in using an actual siwak (tooth-stick). This is what the Prophet (Allah bless him & give him peace) used, for countless wisdoms and benefits that the scholars have ably outlined.
And Allah knows best.
Wassalam,
Faraz.