A new birth cohort study that followed 3,196 children from birth to age 5 found that cavities in baby teeth begin appearing as early as age 2 and climb every year after that, reaching about 4.4 percent of children by age 5. The research, published June 8, 2026 in Community Dentistry and Oral Epidemiology, singled out two factors as the most consistent warning signs across every age: weaning a child off the breast or bottle later than 24 months, and close contact with household pets. For parents, the practical takeaway is simple. The habits that protect baby teeth need to start in infancy, well before the first cavity is ever visible.
Key facts at a glance
- Parent reported cavities rose steadily with age, from 0.4 percent at age 2 to 1.3 percent at age 3, 2.7 percent at age 4, and 4.4 percent at age 5 (Community Dentistry and Oral Epidemiology, 2026).
- The study enrolled 3,196 newborns and their families in and around Regensburg, Germany, and tracked them with repeated questionnaires from 2015 to 2020 (Lennon et al., 2026).
- Weaning later than 24 months and contact with pets were the two factors most consistently linked to early cavities across all ages, though the authors caution that the pet finding needs more study before it changes any advice (Community Dentistry and Oral Epidemiology, 2026).
When do cavities actually start in young children?
Cavities can start much earlier than many families expect, with measurable rates appearing by age 2 and roughly doubling every year through the preschool years. In this study, parent reported cavities climbed from 0.4 percent at age 2 to 4.4 percent by age 5, and the rate was slightly higher, at 4.7 percent by age 5, among the group of children who had actually been to a dentist. That upward curve matters because baby teeth hold space for adult teeth, help children chew and speak, and, once decay sets in, can cause pain, infection, and missed school. The message for parents is that the window for prevention opens with the very first tooth, not at the first school checkup.
The study design was a repeated questionnaire survey of preschoolers ages 2 to 5, drawn from a larger birth cohort. Sample sizes shrank over time as families dropped out, from 1,296 children at age 2 to 768 at age 5, which is normal for long running cohort research but is worth keeping in mind when reading the numbers.
Which risk factors did the study flag?
The strongest and most repeated signals were late weaning and pet contact, but the study flagged a long list of social, health, and habit related factors that shifted from year to year. Some of these are things families can directly change, such as toothbrushing habits, diet, and weaning timing. Others describe a family's circumstances rather than a daily choice, and a few, most notably pet exposure, are early signals the researchers themselves say are not yet ready to guide advice. The table below sorts the reported factors by how useful they are for a parent trying to act today.
| Type of factor | Examples reported in the study | What it means for families |
|---|---|---|
| Habits you can change | Weaning later than 24 months, inadequate toothbrushing at age 2, poor diet at age 5, pacifier hygiene issues | These are the clearest, most actionable targets for prevention starting in infancy. |
| Family and health context | Single parent status, lower parental education, a sibling with cavities, younger maternal age, infrequent maternal dental visits | Useful for spotting children who may need extra support and earlier dental contact, not personal blame. |
| Early signals needing more research | Household pet contact, mouth breathing at age 1, early tooth eruption, low body mass index at age 1 | Interesting associations the authors say should not yet change prevention advice. |
Should parents worry about pets causing cavities?
No, families should not read this study as a reason to rehome the family dog or cat. Pet contact showed up as a statistical association, not a proven cause, and the researchers were explicit that this link needs to be understood far better before it means anything for a child's daily routine. An association like this can reflect many overlapping factors in a household rather than the pet itself. In the authors' words, the pet finding is a lead for future research, not a recommendation. Parents are far better served by focusing on the factors that are already well proven, such as brushing, diet, and timely dental visits.
"Weaning later than 24 months and contact with pets were the factors most consistently associated with parent reported caries across all ages," the study authors reported, while adding that "further research is needed to clarify the role of newly identified environmental factors, especially pet exposure, before they can be incorporated into caries prevention recommendations."
What can families do right now to protect baby teeth?
The most effective steps are the simple, boring ones that start in the first year of life and stay consistent. Based on this study and on long standing pediatric dental guidance, families can focus on a short list of high value habits:
- Begin cleaning your child's mouth before teeth even appear, and brush twice a day with a smear of fluoride toothpaste once the first tooth comes in.
- Plan to move your child off the bottle around their first birthday and avoid letting a toddler carry a bottle of milk or juice through the day or to bed, since pooled sugars feed decay.
- Keep sugary drinks and frequent snacking to a minimum, and offer water between meals.
- Book the first dental visit by age 1, or within six months of the first tooth, so a dentist can catch early white spot lesions before they become cavities.
That first visit is where a lot of prevention happens, from fluoride varnish to feeding and brushing coaching tailored to your child. Families searching for a provider who focuses on young children can browse verified pediatric practices in our directory, such as Super Kids Dental in Riverside, California, and compare reviews and services before booking. If your child already has an early cavity, it is also worth reading our explainer on silver diamine fluoride, the no drill option for stopping cavities in kids, which many family and pediatric dentists now offer.
How does this fit with what United States dentists already recommend?
It reinforces guidance that pediatric dental groups in the United States have given for years, that prevention should start in infancy and that the first dental visit belongs around a child's first birthday. The American Academy of Pediatric Dentistry recommends an initial oral evaluation within six months of the first tooth erupting and no later than age 1, a schedule laid out in its periodicity of examination guidance. The Centers for Disease Control and Prevention likewise stresses daily brushing with fluoride toothpaste and limiting sugary drinks in its oral health tips for children. The new cohort study, first reported by DrBicuspid, adds fresh evidence about the timing of decay and the weight of weaning habits, but its core lesson lines up with advice families can already act on in any dental office.
Frequently asked questions
At what age should my child first see a dentist?
By age 1, or within six months of the first tooth coming in, whichever is earlier, according to the American Academy of Pediatric Dentistry. Early visits are short, gentle, and focused on prevention and coaching for parents.
Does prolonged breastfeeding or bottle feeding cause cavities?
The study linked weaning after 24 months to a higher rate of early cavities, but this is about how and when sugars sit on the teeth, not a reason to stop breastfeeding on a strict deadline. The practical fix is to clean the teeth after feeds, avoid a bottle in bed, and talk with your pediatric dentist about timing that fits your family.
My toddler has no visible cavities. Do we still need to worry?
Yes, because decay starts invisibly as chalky white spots before it becomes a hole, and it climbs quickly in the preschool years. Consistent brushing, limited sugary drinks, and regular checkups are what keep those early spots from turning into cavities.
Should I keep my pet away from my child because of this study?
No. The pet link is an unexplained statistical association, and the researchers said plainly that it is not ready to guide any advice. Focus your energy on brushing, diet, and dental visits instead.
Updated July 2026. This article summarizes published research and general dental guidance and is not a substitute for personalized advice from your child's dentist.
