Late Teething: Is It a Sign of Autism?

Parents closely monitor their baby’s milestones, including teething. While some infants follow typical timelines, others experience delays, raising concerns about possible underlying conditions. One question that arises is whether late teething is linked to autism.

Understanding the factors influencing teething and its relationship to neurological development can help address misconceptions.

Typical Infant Teething Timelines

Primary teeth usually emerge in a predictable sequence, though individual variation is common. Most infants begin teething around six months, with lower central incisors appearing first. The process continues with upper central incisors, lateral incisors, first molars, canines, and second molars. By age three, most children have a full set of 20 primary teeth. While this timeline serves as a guideline, deviations of a few months are often normal.

Genetics, nutrition, and overall health influence teething. Children often follow similar teething patterns to their parents. Nutritional deficiencies, particularly in vitamins D and A, can delay eruption. Premature birth and low birth weight have also been associated with later teething due to their effects on growth and development.

Population studies show broader trends. Research in the Journal of Dental Research indicates teething onset varies across ethnic groups. Environmental factors, such as fluoride exposure and diet, also play a role. Breastfed infants may experience slightly delayed eruption compared to formula-fed babies due to differences in nutrient intake and jaw development.

Observed Delays in Eruption Patterns

When teeth emerge significantly later than expected, concerns about developmental influences arise. Delayed teething is typically defined as the absence of any erupted teeth by 13 to 15 months. Research in Pediatric Dentistry suggests minor delays are often normal, but more pronounced deviations may indicate systemic factors affecting growth. A study in The Journal of Clinical Pediatric Dentistry found infants with delays beyond 18 months were more likely to have slower skeletal development, reinforcing the link between dental and overall growth.

Endocrine function plays a role in tooth eruption. Thyroid hormone, particularly thyroxine, regulates the pace of eruption. Hypothyroidism in infancy has been linked to significant delays, as shown in The Journal of Endocrinology and Metabolism, which reported children with congenital hypothyroidism experienced eruption delays of four to six months. Growth hormone deficiencies can also impact timing and sequence.

Nutritional status is another key factor. Deficiencies in calcium and phosphorus, essential for enamel and dentin formation, slow mineralization. A meta-analysis in Advances in Nutrition found prolonged vitamin D deficiency was linked to delayed teething and enamel hypoplasia. Population studies in regions with high malnutrition rates confirm these findings, highlighting the importance of adequate nutrient intake.

Genetics also influences eruption schedules. Twin studies in The American Journal of Human Genetics show a strong hereditary factor, with monozygotic twins exhibiting highly similar eruption patterns. Certain genetic conditions, such as Down syndrome, are associated with significantly delayed teething, as individuals with trisomy 21 often experience late eruption alongside altered tooth morphology. Similarly, cleidocranial dysplasia, a disorder affecting cranial and dental development, can result in teeth emerging years later than average.

Correlations With Neurological Development

The relationship between teething delays and neurological development has been studied, particularly in connection with autism spectrum disorder (ASD). While tooth eruption is primarily a physiological process, it occurs alongside other developmental milestones. Researchers have explored whether delayed teething could indicate neurodevelopmental variations, as atypical motor and sensory development is frequently reported in children with ASD.

Brain growth and dental development share regulatory mechanisms through genes involved in craniofacial and neurological maturation. Studies on children with ASD have noted differences in tooth eruption timing, enamel formation, and cranial morphology, suggesting broader genetic and developmental influences. A genome-wide association study in Nature Genetics identified overlapping genetic pathways affecting both dental and neural development. However, while these findings suggest a connection, they do not establish a direct causal link between late teething and autism.

Sensory processing differences in children with ASD may also influence oral development. Infants with heightened or diminished oral sensitivities often exhibit variations in feeding behaviors, which can affect jaw stimulation and muscular function—both of which contribute to eruption. Some studies propose that altered sensory-motor integration in ASD may play a role in delayed teething, though further research is needed. Additionally, differences in hormone regulation, particularly involving insulin-like growth factor 1 (IGF-1), have been linked to both delayed tooth eruption and atypical brain development. Research in Pediatric Neurology found that children with ASD may exhibit altered IGF-1 levels, which influence craniofacial growth and neural connectivity.

Influential Genetic and Environmental Factors

Teething timelines are shaped by genetics and environmental influences. Studies on familial patterns show children often follow similar schedules to their parents and siblings, suggesting a strong genetic component. Genes such as MSX1 and PAX9 regulate tooth bud formation and influence eruption timing. Mutations or variations in these genes can lead to delayed eruption, sometimes alongside other dental anomalies like missing or malformed teeth.

Environmental factors also play a role, with nutrition being especially influential. Calcium, phosphorus, and vitamin D are essential for enamel and dentin formation, and deficiencies in these nutrients can slow mineralization. Geographic disparities in teething timelines have been observed, with infants in areas with limited sunlight—affecting vitamin D synthesis—more likely to experience delays.

Approaches for Parents and Caregivers

When teeth emerge later than expected, parents often seek reassurance. While delays can be concerning, tracking overall development provides a clearer picture. Pediatricians and dentists assess teething alongside motor skills, speech progression, and physical health to determine if further evaluation is needed. Keeping a developmental journal that records milestones such as crawling, babbling, and fine motor coordination can help healthcare professionals assess a child’s growth.

Parents can support oral development even before teeth emerge. Gum stimulation through gentle massage or teething toys promotes circulation and may aid eruption. Ensuring adequate intake of calcium, phosphorus, and vitamin D supports proper mineralization. If teething is significantly delayed beyond 15 months, consulting a pediatric dentist can help rule out underlying concerns.

Collaborating With Dental and Medical Experts

Healthcare professionals play a key role in evaluating delayed teething. Pediatric dentists can use imaging techniques like panoramic X-rays to assess tooth development and identify structural abnormalities such as impaction or missing teeth. If concerns extend beyond dental issues, pediatricians may recommend endocrinological or genetic testing to explore underlying conditions.

Interdisciplinary collaboration ensures a thorough evaluation of developmental patterns. When late teething coincides with other atypical milestones, developmental pediatricians or neurologists may assess broader neurological or metabolic factors. While delayed tooth eruption alone is not a definitive indicator of autism or other neurodevelopmental conditions, a multidisciplinary approach provides a comprehensive understanding of a child’s health. Early intervention programs can offer additional support when needed, ensuring children receive appropriate care.