✅ Answer: One of the emphasized practices with numerous benefits in our narrations is miswak (teeth cleaning).

The origin of miswak is from branches of various trees, as mentioned in the following narration:

عَنْ سَهْلٍ عَنْ مَنْصُورِ بْنِ الْعَبَّاسِ عَنِ ابْنِ أَبِی نَجْرَانَ أَوْ غَیْرِهِ عَنْ حَنَانٍ عَنْ أَبِیهِ عَنْ أَبِی جَعْفَرٍ ع قَالَ شَکَتِ الْکَعْبَةُ إِلَی اللَّهِ عَزَّ وَ جَلَّ مَا تَلْقَی مِنْ أَنْفَاسِ الْمُشْرِکِینَ فَأَوْحَی اللَّهُ إِلَیْهَا قِرِّی کَعْبَةُ فَإِنِّی مُبْدِلُکِ بِهِمْ قَوْماً یَتَنَظَّفُونَ بِقُضْبَانِ الشَّجَرِ فَلَمَّا بَعَثَ اللَّهُ مُحَمَّداً ص أَوْحَی إِلَیْهِ مَعَ جَبْرَئِیلَ بِالسِّوَاکِ وَ الْخِلَالِ

📚 Al-Kafi, Vol. 4, p. 546

Imam Baqir (peace be upon him) said: The Ka'bah complained to the Lord about the foul breaths of the polytheists, so God revealed to it: 'O Ka'bah, be at peace, for I will replace them with a people who clean themselves with the branches of trees.' When Allah sent Muhammad (peace be upon him), He revealed to him the miswak and the toothpick through Gabriel.

✅ However, some woods, like reed, are prohibited for miswak and toothpicks. The best type is introduced in the following narration, which mentions the Arak tree branch:

الرِّسَالَةُ الذَّهَبِيَّةُ، لِلرِّضَا وَ اعْلَمْ يَا أَمِيرَ الْمُؤْمِنِينَ أَنَّ أَجْوَدَ مَا اسْتَكْتَ بِهِ لِيفُ الْأَرَاكِ فَإِنَّهُ يَجْلُو الْأَسْنَانَ وَ يُطِيبُ النَّكْهَةَ وَ يَشُدُّ اللِّثَةَ...

📚 Mustadrak, Vol. 1, p. 369

Translation: Imam Reza (peace be upon him) said to Ma'mun: 'Know, O Ma'mun, that the best thing to use for miswak is the wood of the Arak tree, for it polishes the teeth, freshens the breath, and strengthens the gums.'

Also, according to the following narration, Imam Reza (peace be upon him) used different miswaks:

مُحَمَّدُ بْنُ عَلِیِّ بْنِ الْحُسَیْنِ بِإِسْنَادِهِ عَنْ مُعَمَّرِ بْنِ خَلَّادٍ عَنْ أَبِی الْحَسَنِ الرِّضَا قَالَ کَانَ وَ هُوَ بِخُرَاسَانَ إِذَا صَلَّی الْفَجْرَ جَلَسَ فِی مُصَلَّاهُ إِلَی أَنْ تَطْلُعَ الشَّمْسُ ثُمَّ یُؤْتَی بِخَرِیطَةٍ فِیهَا مَسَاوِیکُ فَیَسْتَاکُ بِهَا وَاحِداً بَعْدَ وَاحِدٍ ثُمَّ یُؤْتَی بِکُنْدُرٍ فَیَمْضَغُهُ (ثُمَّ یُؤْتَی) بِالْمُصْحَفِ فَیَقْرَأُ فِیهِ

📚 Man La Yahduruhu al-Faqih, Vol. 1, p. 504

Amir ibn Khalad said: When Imam Reza (peace be upon him) was in Khorasan, after performing the Fajr prayer, he would sit at his prayer place until the sun rose. Then they would bring him a bag containing miswaks, and he would use them one after another. Afterward, they would bring him mastic and he would chew it, then he would leave it, and they would bring him the Quran, and he would engage in its recitation.

Furthermore, other types of miswaks are also introduced, and their narrations are mentioned:

عَنْ عَلِیٍّ بِإِسْنَادِهِ قَالَ أَدْنَی السِّوَاکِ أَنْ تَدْلُکَهُ بِإِصْبَعِکَ

📚 Al-Kafi, Vol. 3, p. 23

Imam Ali (peace be upon him) said: The minimum level of miswak is to rub it with your finger.

عَنْ عَلِیِّ بْنِ الْحَکَمِ عَنْ عِیسَی بْنِ عَبْدِ اللَّهِ رَفَعَهُ قَالَ قَالَ رَسُولُ اللَّهِ صلی الله علیه و آله أَفْوَاهُکُمْ طَرِیقٌ مِنْ طُرُقِ رَبِّکُمْ فَأَحَبُّهَا إِلَی اللَّهِ أَطْیَبُهَا رِیحاً فَطَیِّبُوهَا بِمَا قَدَرْتُمْ عَلَیْهِ

📚 Al-Mahasin, Vol. 2, p. 559

The Messenger of Allah (peace be upon him) said: 'Your mouths are paths to your Lord, and the most beloved to Allah is the one that is the sweetest in fragrance. Therefore, make your mouths fragrant with whatever means you have available.'

Based on the above narrations, it is clear that the best type of miswak is from the Arak tree. However, based on the general teachings, modern toothbrushes are not excluded from the concept of miswak, which is a tool for cleaning the teeth. It is recommended to benefit from the Arak wood and its benefits mentioned in Imam Reza's narration, but if Arak wood is not accessible for any reason, using other miswaks is also permissible.

InshaAllah.