In Jainism, particularly during periods of special religious observance like Athai (Ashtahnika Parva)—an eight-day period of heightened spiritual discipline—devotees strive to increase their level of self-control and minimize himsa (violence) in daily activities.

Brushing Teeth During Athai:

• Many devout Jains avoid brushing their teeth with a toothbrush and toothpaste during Athai, especially in the mornings. This is because brushing can inadvertently harm microscopic organisms (nigodas) and small insects, which is considered a form of himsa.
• Instead, some may use methods that minimize harm, such as rinsing the mouth with water or using a soft cloth, or avoiding even that, depending on their level of observance and guidance from their spiritual teacher (Guru or Acharya).
• The practice may also vary according to Jain sects (Shwetambar and Digambar) and personal vows.

Summary: Devout Jains often refrain from brushing their teeth in the conventional way during Athai to observe greater non-violence. It is best to follow guidance from your tradition or consult with a Jain monk or scholar for specific practices.