Tooth cavities are one of the most common dental problems, yet many people delay treatment until pain becomes severe. This comprehensive guide explains the different stages of cavity development — from early enamel damage to deep infection — and highlights when a simple dental filling is sufficient and when advanced treatment like root canal therapy may be required. The PDF also clarifies the role of modern digital dental X-rays in detecting hidden decay between teeth and under old fillings, ensuring accurate and timely diagnosis. Readers will learn about early warning signs, preventive care tips, treatment options, and the importance of seeking professional dental evaluation before complications arise. Prepared by Kaizen Dental, this educational resource focuses on conservative, minimally invasive dentistry and patient awareness. It is designed to help individuals make informed decisions about cavity treatment, protect their natural teeth, and maintain long-term oral health through early intervention and preventive care.