Patterns of tooth agenesis in individuals with Down syndrome: A secondary analysis using the Tooth Agenesis Code.

Aims: Tooth agenesis (TA) is common in Down syndrome (DS). It is unknown whether this agenesis occurs in specific patterns, which is important regarding treatment planning and aetiological research. This study aimed to aggregate and analyze patterns of TA, excluding third molars, in individuals with DS using the tooth agenesis code (TAC).

Methods and results: The study was designed as a secondary analysis, following STROSA guidelines. The search (MEDLINE-PubMed) and selection process resulted in six included studies encompassing 241 individuals with DS. TA data were systematically converted into TACs and analyzed per dentition, per jaw, and per tooth type. Symmetry was evaluated. The prediction was calculated for oligodontia. In the 155 cases with TA 86 distinct Overall-TAC patterns were identified. The most common patterns were bilateral maxillary lateral incisor agenesis (TAC002.002.000.000;10.3%), bilateral mandibular second premolar agenesis (TAC000.000.016.016;5.8%), and unilateral left maxillary lateral incisor agenesis (TAC000.002.000.000;5.2%). Symmetry in TA patterns was observed in 49.6% of TA cases in the maxilla and 52.3% in the mandible. The simultaneous absence of both mandibular central incisors had a large predictive value for oligodontia (OR12.44;95% CI:4.97-31.84; p < .001).

Conclusion: Predominant TA patterns exist in DS. Observation of mandibular central incisor agenesis can promote early diagnosis of oligodontia in DS.