Monocyte preseeding leads to an increased implant bed vascularization of biphasic calcium phosphate bone substitutes via vessel maturation

The present study analyzes the influence of the addition of monocytes to a biphasic bone substitute with two granule sizes (400-700 μm and 500-1000 μm). The majority of the added monocytes was detectable as mononuclear cells, while also low amounts of (chimeric) multinucleated giant cells (MNGCs) were found. No increase in the total number of MNGCs was established, but a significantly increased percent vascularization. Altogether, the results show that the added monocytes become involved in the tissue response to a biomaterial without marked changes in the overall reaction. Monocyte addition enables an increased implant bed vascularization especially via induction of vessel maturation and, thus intervenes positively in the healing reaction to a biomaterial. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2928-2935, 2016.

Small-sized granules of biphasic bone substitutes support fast implant bed vascularization

The present study investigated the influence of granule size of 2 biphasic bone substitutes (BoneCeramic® 400–700 μm and 500–1000 μm) on the induction of multinucleated giant cells (MNGCs) and implant bed vascularization in a subcutaneous implantation model in rats. Furthermore, degradation mechanisms and particle phagocytosis of both materials were examined by transmission electron microscopy (TEM). Both granule types induced tissue reactions involving primarily mononuclear cells and only small numbers of MNGCs. Higher numbers of MNGCs were detected in the group with small granules starting on day 30, while higher vascularization was observed only at day 10 in this group. TEM analysis revealed that both mono- and multinucleated cells were involved in the phagocytosis of the materials. Additionally, the results allowed recognition of the MNGCs as the foreign body giant cell phenotype. Histomorphometrical analysis of the size of phagocytosed particles showed no differences between the 2 granule types. The results indicate that granule size seems to have impact on early implant bed vascularization and also on the induction of MNGCs in the late phase of the tissue reaction. Furthermore, the results revealed that a synthetic bone substitute material can induce tissue reactions similar to those of some xenogeneic materials, thus pointing to a need to elucidate their “ideal” physical characteristics. The results also show that granule size in the range studied did not alter phagocytosis by mononuclear cells. Finally, the investigation substantiates the differentiation of material-induced MNGCs, which are of the foreign body giant cell type.

Induction of multinucleated giant cells in response to small sized bovine bone substitute (Bio-Oss™) results in an enhanced early implantation bed vascularization

Purpose:

The host tissue reaction to the xenogeneic bone substitute Bio-Oss™ (Geistlich Biomaterials, Wolhousen, Switzerland) was investigated focusing on the participating inflammatory cells and implantation bed vascularization.

Materials and Methods:

Bio-Oss™ was implanted subcutaneously into CD1 mice for up to 60 days and analyzed by means of specialized histological and histomorphometrical techniques after explantation.

Results:

Bio-Oss™ induced within the first 15 days an early high vascularization combined with a marked presence of multinucleated giant cells. The latter cells were associated mainly with the smaller sized granules within the implantation bed. Toward the end of the study the number of multinucleated giant cells decreased while the tissue reaction to the larger granules was mainly mononuclear.

Conclusion:

The results of the present study showed that smaller xenogeneic bone substitute granules induce multinucleated giant cells, whereas the larger-sized ones became integrated within the implantation bed by means of a mononuclear cell-triggered granulation tissue. Obviously, the presence of multinucleated giant cells within biomaterial implantation beds is not only related to the type of synthetic bone substitute material, but also to the granule size of the natural-based xenogeneic bone substitute material.

Tissue reaction to sealing materials: different view at biocompatibility

The biodegradability of root canal sealers in areas other than the root canal system is crucial to the overall success rate of endodontic treatment. The aim of the present study was to investigate, the cell and tissue reaction to GuttaFlow and AHPlus, both in vitro and in vivo. For the in vitro experiments the materials were incubated with Human Periodontal Ligament Fibroblasts and cell proliferation and cytotoxicity analyses were performed. Additional fluorescence-microscope stainings were carried out in order to visualize cell growth and morphology. For assessment of the tissue reaction to the materials a subcutaneous implantation model in Wistar rats was employed and the inflammatory response to the materials was visualized by means of general and specific histology after 6 weeks. Human gingival fibroblasts proliferation seemed to be dependent upon dental material and cultivation time. After an incubation period of 96 hrs AHPlus proved to be significantly (p < 0.002) more cytotoxic than GuttaFlow, as only a small number of fibroblasts survived on AHPlus. In vivo, GuttaFlow was surrounded by a fibrous capsule and no degradation took place, while AHPlus induced a well-vascularized granulation tissue in which the material was phagocyted by macrophages. The results of this study demonstrate that a potential cytotoxic effect of a sealing material may beneficial in order to have antibacterial properties and induce self degradation when accidentally extruded over the apical foramen.

[A long-term 3D cast model analysis focusing bone-borne vs. tooth-borne SARME]

This retrospective study evaluated 34 patients pre- and ~20.5 months post expansion 3D scanned cast models with tooth-borne (ТВ, n1=16) and bone-borne (BB, n2=18) devices. Measurements were performed for transverse skeletal/dental maxillary widening, dental tipping and dental attachment loss.

RESULTS

T-Test in long-term effects: BB: bigger, symmetric transverse widening along the dental arch; bigger attachment loss in the frontal teeth, canines, 2nd premolars. molars; bigger dental tipping in the canines and 2nd molars; ТВ: asymmetric transverse widening along the dental arch; bigger attachment loss in the 1st premolars: bigger dental tipping in the premolars and 1st molars.

CONCLUSION

BB should be used whenever bigger transverse maxillary expansion is required, new distractor designs may reduce segmental inclination and initial expansion asymmetries, consequently, eliminating the related attachment loss from secondary orthodontic tooth movements for arch alignment. ТВ devices showed minor expansion with good periodontal attachment, yet attachment loss in the first premolars must be critically seen in bigger expansion distances.

Maxillary sinus grafting with a nano-structured biomaterial: preliminary clinical and histological results

BACKGROUND

In this study the potential of a new and entirely synthetic, nano-structured hydroxyapatite-based biomaterial for sinus floor augmentation is evaluated.

METHODS

20 sinus floor elevations were carried out in a total of 20 patients. After a healing period of 6 months, in 10 cases cylinder-shaped bone biopsies were taken from the augmented maxillary region using trephine burs.

RESULTS

The healing period progressed without any complications. General and specific histological analysis of the bone biopsies showed a high osteoclast activity at the margin of the biomaterial which was well integrated into the newly formed bone.

CONCLUSION

This study demonstrates that new trabecular bone is formed after grafting with the nanocrystalline bone substitute after 6 months. Ongoing histomorphological studies are necessary to quantify the biomaterial-bone ratio and the exact amount of newly built bone in the augmented cavity after 6 months.