Histological and histochemical quantification of root resorption incident to the application of intrusive force to rat molars

Abstract

This study was conducted to investigate the nature of root resorption resulting from intrusive forces applied to the rat lower molars, by means of histological and histochemical techniques with tartrate resistant acid phosphatase (TRAP). Thirty-eight 13-week-old Wistar strain male rats were used. Intrusive force was created by a fixed appliance which was adjusted to exert an initial force of 50 g for the duration of 1, 2, and 3 weeks. The degree of root resorption and distribution of TRAP positive cells were evaluated. On the root surface, the TRAP positive scores were low in the apical regions. Significant differences in the scores were found in the inter-radicular region of the roots between the experimental and control groups for the 2- and 3-week groups. More active resorption of bone occurred during the experimental period, as denoted by greater TRAP positive scores on the bone than on the root surface. Root resorption scores in the apical root region were larger in the 2- and 3-week groups than in the 1-week group. Significant differences in the root resorption scores were also found between the 1- and 3-week groups in the inter-radicular region, indicating that intrusive force application of a longer duration may lead to a higher frequency of root resorption. It is shown that, irrespective of the level of TRAP positive cells and root resorption scores, the degree of root resorption activity is higher in the apical root region than in the inter-radicular area. These results indicate that cellular cementum may be resorbed more easily because of its richer organic components and low mineralized structure.

Premolar Root Changes Following Treatment with the Banded Herbst Appliance

“…Die Intrusion wird als ein Typ der Zahnbewegung angesehen, der Wurzelresorptionen hervorrufen kann [8,10,15,17,19,23,31], auch wenn darüber keine generelle Einigkeit besteht [6]. In der Tat entstehen intermittierende intrusive Kräfte und Momente von unterschiedlicher Größe und Dauer bei der Behandlung mit der Herbst-Apparatur [25], deren Auswirkungen auf die verankernden Prämolaren noch nicht untersucht wurden.…”

“…Intrusion is regarded as a type of tooth movement that may cause root resorption [8,10,15,17,19,23,31], although some disagree [6]. Indeed, treatment with the Herbst appliance produces Einleitung Die Herbst-Apparatur ist ein festsitzendes funktionelles Behandlungsgerät, das mit Erfolg zur Therapie ausgepräg-ter Klasse-II/1-und -II/2-Anomalien eingesetzt wurde [13,27,29].…”

Orthodontic mechanotransduction and the role of the P2X7 receptor

“…Similarly, the hyalinization score was obtained by counting the total number of squares that contained necrotic tissue, and dividing by the total number of squares in the compressive side of the PDL. These methods are a higher resolution modification of a previously developed protocol (AlQawasmi et al, 2006;Lu et al, 1999). The identification of cell types was performed with the assistance of an experienced pathologist.…”

Age-dependent external root resorption during tooth movement in rats

“…The appliance design has been described in detail in a previous publication [20]. Briefly, a split-mouth design was used with the experimental side chosen randomly, and with the contralateral side as the control.…”

“…a mixing-up of the incidence and severity of resorption [19], investigation only of the pressure surfaces [18], no discrimination of the pressure and tension regions [19], and application of heavy forces [20]. Our aim was to test the following hypotheses over a 12-week observation period with a light continuous force in rats: orthodontic tooth movement increases the incidence and severity of root resorption; both incidence and severity are higher in adult rats than in young rats and higher in the middle part of the roots than in the apical and cervical parts.…”