Background Molar‐incisor malformation (MIM) is a recently described dental abnormality. While MIM mimics dentin dysplasia, it presents in a localized pattern. Furthermore, it is speculated that MIM is caused by significant early‐life medical history. Aim The purpose of this study is to present a series of MIM cases and compare the findings with the literature. Design An extensive search of all published cases of MIM in the English‐language literature was conducted. Additionally, an institutional review board‐approved retrospective search was performed within the University of Florida oral pathology biopsy service archives. Radiographic consultation cases were also included. Cases lacking radiographs were excluded. Results Seventy‐nine cases were identified in the literature, and eight cases were identified in our retrospective search. All but one case involved the permanent first molars. The average age at diagnosis was 9 years. Many patients reported significant early‐life medical histories. Conclusions MIM usually affects the permanent first molars and may be linked to early‐life medical conditions or interventions. Oral healthcare providers, especially paediatric dentists, should be aware of MIM to avoid misdiagnosing it as dentin dysplasia. Long‐term follow‐up studies with thorough medical history documentation are essential to understand the pathogenesis and aetiology and to create treatment guidelines.

Geriatric dentistry should be included in the undergraduate curricula of dental schools in Brazil. Postgraduate degree courses should be developed to produce more clinical academics and researchers in this field.

Early childhood caries (ECC) recurrence occurs in approximately 40% of treated cases within one year. The association of Streptococcus mutans and Candida albicans with the onset of ECC is well known. Also, S. mutans strains harboring collagen-binding proteins (Cbps) avidly bind to collagen-rich dentin and are linked to increased caries risk. Here, we investigated the presence of Cbp+S. mutans and C. albicans in saliva and dental plaque of children with varying caries statuses, and their salivary microbiome. In this cross-sectional study, 143 children who were caries-free (n = 73), treated for ECC with no signs of recurrence after 6 months (n = 45), or treated for ECC and experiencing recurrence within 6 months following treatment (n = 25) were enrolled. Co-infection with C. albicans and S. mutans, especially Cbp+S. mutans, was strongly associated with caries recurrence. Subjects of the recurrence group infected with Cbp+S. mutans showed a greater burden of Candida spp. and of Mutans streptococci in dentin than those infected with Cbp- strains. Salivary microbiome analysis revealed that Streptococcus parasanguinis was overrepresented in the caries recurrence group. Our findings indicate that Cbp+S. mutans and C. albicans are intimately associated with caries recurrence, contributing to the establishment of recalcitrant biofilms.