Extreme premolar rotations: a possible addition to the dental anomaly pattern?

Objectives: To investigate the possible association between the presence of extreme premolar rotations (135° to 180° rotated premolars) and other dental anomalies within the dental anomaly pattern (DAP).

Materials and methods: Thirty-two healthy subjects exhibiting at least one premolar rotated 135° to 180° were identified from the archives of a university orthodontic clinic. Inclusion criteria were: presence of a rotated premolar, availability of panoramic radiographs, dental study casts, and intraoral photographs. The concomitant occurrence of additional dental anomalies was evaluated based on the DAP, including tooth agenesis, infraocclusion of deciduous molars, peg-shaped lateral incisors, palatally-displaced canines and transpositions. Comparisons were made to a randomly selected control group (n = 96) without this anomaly, using chi-square statistics.

Results: The experimental group displayed a higher prevalence of dental anomalies compared to the control group. Forty-seven percent of patients in the experimental group exhibited dental agenesis, whereas only 8% of the control group had dental agenesis (P < .001). Infraocclusion of deciduous molars (22% vs 5%; P = .005) and canine impaction (16% vs 3%; P = .035) were also observed more frequently in patients in the experimental group.

Conclusions: These findings reveal significant associations between the presence of extreme premolar rotations and the occurrence of other dental anomalies, namely dental agenesis, infraocclusion of deciduous molars, and palatally-displaced canines. These observations suggest a shared genetic origin for these anomalies.