Objective To determine the frequency of occult trauma in children with oral injury evaluated for physical abuse.

Design This was a retrospectively planned secondary analysis of a prospective, observational study.

Setting Emergency departments supported by 20 US child abuse teams in the Examining Siblings to Recognize Abuse (ExSTRA) network.

Patients Children <120 months old evaluated for physical abuse.

Interventions Analysis of index children with oral injury on initial examination.

Main outcome measures Rates of physician-recognised oral injury, as well as frequency and results of occult injury testing. Perceived abuse likelihood was described on a 7-point scale (7=definite abuse).

Results Among 2890 child abuse consultations, 3.3% (n=96) of children had oral injury. Forty-two per cent were 0–12 months old, 39% 1–3 years old and 18% >3 years old. Oral injury was the primary reason for evaluation for 32 (33%). Forty-three per cent (42/96) had frenum injuries. Skeletal surveys were obtained for 84% and 25% of these identified occult fractures. Seventy-five per cent had neuroimaging; 38% identified injuries. Forty-one per cent of children with oral injuries had retinal examinations; 24% of exams showed retinal haemorrhages. More occult injuries were found in children with oral injuries than other ExSTRA subjects. A high level of concern for abusive injury was present in 67% of children with oral injury versus 33% without.

Conclusions Children with oral injury are at high risk for additional occult abusive injuries. Infants and mobile preschoolers are at risk. Young children with unexplained oral injury should be evaluated for abuse.