Deciduous (baby teeth) teeth begin erupting in puppies at 3-6 weeks of age. They do not develop deciduous molars. Adult incisors erupt at 12-16 weeks of age, canine teeth erupt at 12-20 weeks of age (usually right at 6 months of age), the premolars erupt at 16-20 weeks of age followed by the molars at 20-24 weeks of age. Small dogs often have problems with retained deciduous teeth--baby teeth that do not fall out normally when adult teeth erupt. These deciduous teeth should be extracted at the time of spay; at 6 months of age.