Baby Tooth Eruption Timeline
Primary teeth typically begin erupting at 6-8 months of age, starting with the lower central incisors, and continue until approximately 24-30 months when all 20 primary teeth have emerged. 1
Standard Eruption Sequence
The eruption follows a predictable pattern 1, 2:
- Lower central incisors (first teeth): Median age 7.1 months (males) and 7.6 months (females) 2
- Upper central incisors: Median age 8.7 months (males) and 9.2 months (females) 2
- Upper lateral incisors: Median age 10.0 months (males) and 10.3 months (females) 2
- Lower lateral incisors: Median age 10.4 months (males) and 10.8 months (females) 2
- Complete primary dentition: By approximately 24-30 months (age 3 years) 1, 3
Important Clinical Considerations
Timing variations are common and influenced by multiple factors. The average age of 6 months represents a general guideline, but normal variation exists 3:
- Early eruption: Some infants are born with teeth already present (natal teeth) or develop teeth within the first 30 days of life (neonatal teeth) 4
- Delayed eruption: Premature infants may experience delayed eruption, particularly those with birthweight <1000g or gestational age ≤30 weeks 5
- Gender differences: Males tend to erupt teeth slightly earlier than females across all tooth types 2
Factors Affecting Eruption Timing
Several factors can influence when teeth appear 5:
- Prematurity: Duration of oral intubation alone explains 77% of variability in first tooth eruption timing among premature infants 5
- Nutritional factors: Age when full enteral feedings were attained and average weight gain correlate with eruption timing 5
- Population differences: Indigenous children may experience earlier primary tooth eruption compared to other populations 6, 1
Clinical Action Points
Oral health care should begin immediately with the first tooth eruption, not at an arbitrary age 6, 1:
- Start twice-daily brushing with fluoridated toothpaste (rice grain-sized portion for children <36 months) as soon as the first tooth appears 6, 1
- Schedule the first dental examination within 6 months of first tooth eruption but no later than 12 months of age 1, 7
- Apply fluoride varnish starting with first tooth eruption, then every 3-6 months thereafter 6
The concept that "two is too late" is particularly important for high-risk populations, as newly erupted teeth are most vulnerable to caries and early colonization by cariogenic bacteria occurs soon after eruption 6.