Answer

Yes, in most Jain household practice, brushing teeth is generally avoided during strict upvaas, especially after taking the vow of fasting.

For ekasana, many people brush before starting the vow or before the permitted meal, but practices vary by family, sect, and guru guidance.

Explanation

In Jain Dharma, during upvaas or ekasana, the main concern is not only food, but also:

• avoiding unnecessary intake through the mouth,
• maintaining discipline over taste and bodily comfort,
• reducing himsa as much as possible,
• following the vow exactly as taken.

Brushing may involve toothpaste, water, taste, and possible swallowing. Because of this, many people avoid brushing once the fast has begun.

A common practice is:

• Before upvaas begins: brush normally before taking the vow.
• During upvaas: avoid brushing; rinse only if allowed by your tradition.
• During ekasana: brush before the meal or before taking the vow, depending on your family tradition.

Spiritual Understanding

The purpose of upvaas and ekasana is self-control, inner purity, and detachment from bodily comfort. So the safest approach is to follow the stricter rule and avoid anything that may create taste, attachment, or accidental intake.

Takeaway

If you are doing a strict Jain upvaas, avoid brushing after the fast has started. For ekasana, brush before the vow or meal if your tradition allows it. For exact observance, follow your guru, family tradition, or sampraday rules.