We read with great interest the article on dental development in children with hypodontia (Tunç ES, Bayrak S, Koyutürk AE. Dental development in children with mild-to-moderate hypodontia Am J Orthod Dentofacial Orthop 2011;139:334-8).

The authors compared dental development in a group of children with mild-to-moderate hypodontia with that of a matched group without hypodontia. They used a modified method of dental age estimation developed for hypodontia patients that will be useful for clinicians when assessing their dental development. But there are still some limitations to which we want to draw attention, and we also have some ideas to share and discuss with the readers.

The authors stated that “Dental development in children with mild-to-moderate hypodontia was significantly delayed compared with the control group.” However, the factors that might affect their dental development were not discussed. As stated in the literature, dental development is a multifactorial phenomenon. In a study investigating dental development in patients with unilateral posterior crossbite, patients with crossbite had a tendency for delayed dental development compared with the control group without crossbite. On the other hand, the results of our recent study showed that the dental ages of patients with sagittal skeletal malocclusions (Class II and Class III) were approximately twice as advanced when compared with patients without sagittal skeletal anomaly patterns (Class I). Therefore, those factors and others that might affect dental development in children with mild-to-moderate hypodontia should be discussed. In addition, did the authors evaluate the skeletal patterns (sagittal, transversal, and vertical) of the subjects in the study? If they did not, as seen in the article, readers might consider this situation while reading the article.

We agree with the authors that a few previous studies have investigated dental development in children with hypodontia. One of them was the study of Kan et al, who found results similar to the present study. They showed that both girls and boys with hypodontia showed a significant delay in dental development compared with case controls.

One more question is about the statistical methods used. Even if these statistical tests were correct, we would like to know whether the authors performed a sample size calculation before the study. Since we don’t know whether this study was sufficiently powered, we don’t know whether these findings are statistically correct and sufficiently powered.