Effects of mechanical repetitive load on bone quality around implants in rat maxillae

Abstract

Greater understanding and acceptance of the new concept “bone quality”, which was proposed by the National Institutes of Health and is based on bone cells and collagen fibers, are required. The novel protein Semaphorin3A (Sema3A) is associated with osteoprotection by regulating bone cells. The aims of this study were to investigate the effects of mechanical loads on Sema3A production and bone quality based on bone cells and collagen fibers around implants in rat maxillae. Grade IV-titanium threaded implants were placed at 4 weeks post-extraction in maxillary first molars. Implants received mechanical loads (10 N, 3 Hz for 1800 cycles, 2 days/week) for 5 weeks from 3 weeks post-implant placement to minimize the effects of wound healing processes by implant placement. Bone structures, bone mineral density (BMD), Sema3A production and bone quality based on bone cells and collagen fibers were analyzed using microcomputed tomography, histomorphometry, immunohistomorphometry, polarized light microscopy and birefringence measurement system inside of the first and second thread (designated as thread A and B, respectively), as mechanical stresses are concentrated and differently distributed on the first two threads from the implant neck. Mechanical load significantly increased BMD, but not bone volume around implants. Inside thread B, but not thread A, mechanical load significantly accelerated Sema3A production with increased number of osteoblasts and osteocytes, and enhanced production of both type I and III collagen. Moreover, mechanical load also significantly induced preferential alignment of collagen fibers in the lower flank of thread B. These data demonstrate that mechanical load has different effects on Sema3A production and bone quality based on bone cells and collagen fibers between the inside threads of A and B. Mechanical load-induced Sema3A production may be differentially regulated by the type of bone structure or distinct stress distribution, resulting in control of bone quality around implants in jaw bones.

System for application of controlled forces on dental implants in rat maxillae: Influence of the number of load cycles on bone healing

“…This suggests at least some commonality in mechanobiological factors influencing bone healing around implants in tibial and maxillary sites. The results (Uto et al, 2017) are difficult to compare with the present paper due differences in the total number of loading frequency and the site where the implants were placed. However, it is interesting to note that under acceptable loading, the bone mineral density was increased and also stimulated the bone formation which is in agreement with what Leucht et al (2007) reported.…”

“…In fact, studies on bone healing under controlled loading are carried out mostly in the tibiae of rodents (de Barros et al, ; Jariwala et al, ; Leucht et al, ; Vandamme et al, ; Wazen et al, ; Willie et al, ), and the results are extrapolated to the oral environment. In a recent report, Uto et al () used repetitive loading to investigate its impact on bone quality around implants in rat maxillae. Although placed in a tight fit, the implant was not shielded from external interference during the extended loading period.…”

“…F I G U R E 3 (a) Distribution of 3rd principal strain (compressive) after loading the end of the beam with 1.5 N, and with the modulus of the gap tissue equal to 1 MPa; (b) distribution of 1st principal strain (tensile) after loading the end of the beam with 1.5 N, and with the modulus of the gap tissue equal to 1 MPa; (c) distribution of distortional strain after loading the end of the beam with 1.5 N, and with the modulus of the gap tissue equal to 1 MPa; (d) distribution of hydrostatic strain after loading the end of the beam with 1.5 N, and with the modulus of the gap tissue equal to 1 MPa In fact, studies on bone healing under controlled loading are carried out mostly in the tibiae of rodents (de Barros et al, 2018;Jariwala et al, 2017;Leucht et al, 2007;Vandamme et al, 2007;Wazen et al, 2013;Willie et al, 2010), and the results are extrapolated to the oral environment. In a recent report, Uto et al (2017) used repetitive loading to investigate its impact on bone quality around implants in rat maxillae.…”

Bone quality assessment of osteogenic cell cultures by Raman microscopy

“…In addition, the collagen amide III band at ~1,270 cm −1 is known to be strongly polarization‐dependent compared with the ~1,240 cm −1 band and therefore would be more sensitive to the orientation of collagen fibrils, especially in native bone. It has recently been shown that the orientation and alignment of cells in osteogenic culture can be increased by using artificially orientated collagen scaffolds or by mechanical stimulation . These tissue‐engineering approaches could be employed to provide tissues with the higher degree of anisotropic collagen found in native bone.…”

Epigallocatechin Gallate-Modified Gelatins with Different Compositions Alter the Quality of Regenerated Bones

“…In our results, the mother bone was colored green while bones regenerated by vhEGCG-GS[0.1 and 0.5] were yellow and red. Although alteration of collagen types in bones regenerated by different materials would be an attractive hypothesis, type 1 collagen was the most abundant protein in the bone matrix protein [ 41 ]. Considering the composition of calvaria and its stained data reported previously, it is difficult to conclude that the green color of calvaria obtained in the present study contained sufficient type 3 collagen rather than type 1 collagen.…”