Re: response to: Effects of long-term occlusal hypofunction and its recovery on the morphogenesis of molar roots and the periodontium in rats. The Angle Orthodontist 2013(4) 597–604

To: Editor, The Angle Orthodontist

Thank you very much Dr. Zhao for your interest in our study. I would like to respond to the comments on this study.

The distance between the first molars was analyzed in our study in the hypofunctional group (HG) at 16 weeks of age and the value was 1.8 ± 0.6 mm (n  =  6). Also, a powdered diet (Rodent Diet CE-2; Japan CLEA Inc, Tokyo, Japan) was industrially selected by using mesh so that the diameter of granules was less than 100 µm. Moreover, Figure 8 in our article, which was a 3D reconstructed view, showed intact cusps on the crowns of HG. These data and images indicate that the first molars had been hardly subjected to occlusal stimulation during the experimental period and the method employed was effective in creating the hypofunctional condition of the molar.

The root area was calculated on a cross-sectional plane passing through the middle point of each root. The mesial root in the axial aspect showed a significantly smaller root area in the HG than in the other groups. From these facts, we assumed that the mesial root area in the axial aspect might be smaller in the HG since the midpoint of the elongated root in the HG had shifted towards the apex.

There were no significant differences in mean body weight among the three groups. Therefore, we considered that there is no influence on the normal remodeling of PDL, alveolar bone and even cementum around the molars among control, hypofunctional and recovery conditions.