Development of root resorption during orthodontic tooth movement after cleft repair using different grafting materials in rats

Abstract

Objective The aim of the present study was to investigate the influence of three grafting materials for cleft repair on orthodontic tooth movement in rats. Materials and methods Artificial alveolar clefts were created in 21 Wistar rats and were repaired 4 weeks later using autografts, human xenografts and synthetic bone substitute (beta-tricalcium phosphate/hydroxyapatite [β-TCP/HA]). A further 4 weeks later, the first molar was moved into the reconstructed maxilla. Microfocus computed tomography (μCT) was performed six times (T0–T5) to assess the tooth movement and root resorption. After 8 weeks, the affected reconstructed jaw was resected for histopathological investigation. Results Total distances reached ranged from 0.82 ± 0.72 mm (β-TCP/HA) to 0.67 ± 0.27 mm (autograft). The resorption was particularly determined at the mesiobuccal root. Descriptive tooth movement slowed and root resorption increased slightly. However, neither the radiological changes during tooth movement (µCT T1 vs. µCT T5: autograft 1.85 ± 0.39 mm3 vs. 2.38 ± 0.35 mm3, p = 0.30; human xenograft 1.75 ± 0.45 mm3 vs. 2.17 ± 0.26 mm3, p = 0.54; β-TCP/HA: 1.52 ± 0.42 mm3 vs. 1.88 ± 0.41 mm3, p = 0.60) nor the histological differences after tooth movement (human xenograft: 0.078 ± 0.05 mm2; β-TCP/HA: 0.067 ± 0.049 mm2; autograft: 0.048 ± 0.015 mm2) were statistically significant. Conclusion The autografts, human xenografts or synthetic bone substitute used for cleft repair seem to have a similar effect on the subsequent orthodontic tooth movement and the associated root resorptions. Clinical relevance Development of root resorptions seems to have a secondary role in choosing a suitable grafting material for cleft repair.

Correlations between radiological and histological findings of bone remodelling and root resorption in a rodent cleft model

“…Micro-CT has also been used in experimental research with laboratory animals in the field of cleft treatment [ 27 , 36 , 38 , 39 ]. Recently, we published the results of our investigations on different graft materials used in alveolar cleft repair, the subsequent bone healing process and the development of dental root resorptions in the context of orthodontic tooth movement in a rodent model [ 14 , 15 ]. In the autologous bone graft group, BMD increased from 0.54 ± 0.05 g/cm 3 to 0.62 ± 0.11 g/cm 3 , while in the xenograft group, the values remained unchanged (from 0.43 ± 0.04 g/cm 3 to 0.40 ± 0.04 g/cm 3 ) [ 15 ].…”

“…In contrast, the histological findings showed an increase in the newly formed bone in both groups (autograft: 0.89 ± 0.29 mm 2 ; xenograft: 0.52 ± 0.84 mm 2 ), which was also reflected in the distribution of the newly formed bone on the persistent bone substitute (autograft: 79.45%; xenograft: 62.18%) [ 15 ]. The radiological examination demonstrated an increase in the mesial root resorption in both the autologous (2.38 ± 0.35 mm 3 ) and the xenogeneic groups (2.17 ± 0.26 mm 3 ), while in the histological analysis, resorption in the autologous group was 0.048 ± 0.015 mm 2 and in the xenogeneic group 0.078 ± 0.05 mm 2 [ 14 ]. The bone changes measured with micro-CT were partially in contrast to the histological measurements of new bone formation.…”

“…This model permits the in vivo radiological analysis of the bone structure of the reconstructed area and the associated tooth roots, as well as the corresponding histopathological examination after the trial. The bone graft quality of different substitutes, including autografts, and the root resorptions after cleft repair in the context of subsequent orthodontic treatment have been analysed and compared via radiology and histology methods [ 14 , 15 ].…”

“…In our recently published articles [ 14 , 15 ], contradictory results or discrepancies between the radiological and histological analyses were found. As for the bone microarchitecture of substitutes, bone mineral density (BMD) and BV/TV were higher in the micro-CT of the autograft than the human xenograft, while in the histological analysis, the most persistent grafting material was the human xenograft, which also led to the highest percentage of new bone formation [ 15 ].…”

“…As for the bone microarchitecture of substitutes, bone mineral density (BMD) and BV/TV were higher in the micro-CT of the autograft than the human xenograft, while in the histological analysis, the most persistent grafting material was the human xenograft, which also led to the highest percentage of new bone formation [ 15 ]. The largest root resorption was detected at the mesial root after orthodontic tooth movement of the autograft with the radiological analysis, followed by the human xenograft [ 14 ]. Based on these findings, the previously documented correlation between histological and radiological measurements in different tissues does not seem to exist in this model.…”