Maxillary Sinus Lift with Beta-Tricalcium Phosphate (β-TCP) in Edentulous Patients: A Nanotomographic and Raman Study

Abstract

Sinus lift elevation restores bone mass at the maxilla in edentulate patients before the placement of dental implants. It consists of opening the lateral side of the sinus and grafting beta-tricalcium phosphate granules (β-TCP) under the olfactory membrane. Bone biopsies were obtained in five patients after 60 weeks. They were embedded undecalcified in poly(methyl methacrylate) (pMMA); blocks were analyzed by nanocomputed tomography (nanoCT); specific areas were studied by Raman microspectroscopy. Remnants of β-TCP were osseointegrated and covered with mineralized bone; osteoid tissue was also filling the inner porosity. Macrophages having engulfed numerous β-TCP grains were observed in marrow spaces. β-TCP was identified by nanoCT as osseointegrated particles and as granules in the cytoplasm of macrophages. Raman microspectroscopy permitted to compare the spectra of β-TCP and bone in different areas. The ratio of the ~820 cm band of pMMA (-CH groups) on the ν1 phosphate band at 960 cm reflected tissue hydration because water was substituted by MMA during histological processing. In bone, the ratio of the ~960 cm phosphate to the amide 1 band and the ratio ν2 phosphate band by the 1240-1250 amide III band reflect the mineralization degree. Specific bands of β-TCP were found in osseointegrated β-TCP granules and in the grains phagocytized by the macrophages. The hydration degree was maximal for β-TCP phagocytized by macrophages. Raman microspectroscopy associated with nanoCT is a powerful tool in the analysis of the biomaterial degradation and osseointegration.

Local application of alendronate controls bone formation and β‐tricalcium phosphate resorption induced by recombinant human bone morphogenetic protein‐2

“…It has been recently reported that both osteoclasts and activated macrophages resorb β‐TCP, and these macrophages are positive for TRAP staining (Chappard et al, ; Pascaretti‐Grizon et al, ). It has been also reported that macrophages play a key role in β‐TCP induced osteogenesis and favor osteoblastogenesis from stromal cells present in the bone marrow (Chen et al, ).…”

“…Chappard et al recently shown that both osteoclasts and activated macrophages act together to resorb β‐TCP. It has been shown that these macrophages are also positive for the TRAP reaction (Chappard et al, ; Pascaretti‐Grizon et al, ). Furthermore, there are many studies that bisphosphonates are effective in macrophage depletion (Rogers et al, ; Sabatino et al, ).…”

Bone grafted with β‐TCP granules in the rabbit: A microcomputed tomographic, histologic, Raman microspectrometric, and Raman imaging study

“…[26,38] Raman spectroscopy and imaging also allow evaluation of the hydration of the different area of the graft as MMA infiltrates microporosity and substitutes to water in hydrated tissues during histological embedding. [17,29,46] The most typical peaks is at 813 cm −1 (C O C) and does not overlap with peaks of bone or β-TCP. Hydration, defined at the ratio of 813 cm −1 /ν1 phosphate band, reflects the original water content of the tissue as, in spectroscopy, the ratio of two peak intensities is proportional to the relative amounts of the two corresponding species.…”

“…As reported by a number of papers in the literature, β-TCP is resorbed in vivo by macrophages and osteoclasts that engulf elementary grains of the biomaterial in their cytoplasm. [24,29,47,48] Although these cells can be identified by nanocomputed tomography by their β-TCP content, [[29]] the resolution of our Raman images are not sufficient to identify them clearly. However, some signals are observed in the marrow spaces and do not correspond to a background noise.…”

“…The spectrum of pMMA used for embedding the samples was analyzed in search of the typical representative peaks of pMMA. The C O C symmetric stretching peak at 813 cm −1 is the most representative of pMMA and does not overlap with other bands characteristic of the calcified tissue matrices [29][30][31]. This peak can be used to derive the degree of hydration (or microporosity) of the tissue considered (ratio of bands 813 cm −1 C O C pMMA/960 cm −1 phosphate band).…”