Osseointegration evaluation of an experimental bone graft material based on hydroxyapatite, reinforced with titanium-based particles

Abstract

Bone graft materials are more and more frequently used in dentistry for improving the periodontal support and for creating a bone support favorable for the insertion of dental implants. The experimental study carried out on laboratory animals aimed to evaluate the biocompatibility and the manner of integration of an experimental bone augmentation material, based on hydroxyapatite (HAp), reinforced with titanium-based particles by comparison with a commercial synthetic graft material already existing on the profile market, also based on HAp. We noticed a common pattern of evolution, although there were differences related to the speed of new bone tissue formation and implicitly the morphological elements captured at the two moments of time. In the presence of both synthetic materials, ossification also begins from the center of the cavity at distance from the margins of the bone defect, with a common pattern with an appearance with the presence of osteon-like structures. The experimental material generally determined a more intense initial inflammatory reaction, followed by the generation of a repair bone tissue with a denser appearance but with a less uniform structure and a greater number of residual particles.

Figure 1

Aspect of the cavities made in the parietal bone. The cavity on the left side was left not augmented, while the cavity on the right side was filled with graft material.

Figure 2

Cavity created at the level of the maxillary bone in the retro-incisive area. The cavities on the left side were left not augmented, and those on the right side were filled with augmentation material.

Figure 3

Filling the maxillary cavity with experimental synthetic material and closing the wound.

Figure 4

Calvaria sample collected for histological study.

Figure 5

The appearance of the connective tissue identified in the not augmented control cavity, in a sample from Group A1, presenting an inflammatory infiltrate rich in cells but also a densification of the collagen fibers because of stimulating the activity of fibroblasts. Goldner’s Masson trichrome (GMT) staining, ×200.

Figure 6

Collagen fibers located at the periphery of the defect that tend to form bundles of collagen fibers. GMT staining, ×200.

Figure 7

Bundles of collagen fibers with well-defined directions that foreshadow the future bone trajectories. GMT staining, ×200.

Figure 8

Overview of the tissue that has occupied the bone defect in a sample from Group A1, one month after the application of the commercial material. A well-vascularized connective tissue can be observed, still rich in cells, but also with an important number of fibers and with the presence of a center of ossification at a distance from the edge of the bone defect, initiated by a residual particle of grafting material. GMT staining, ×200.

Figure 9

Overview of the tissue that has occupied the bone defect in a sample from Group B1, one month after the application of the experimental material. The presence of large residual material particles undergoing disintegration is observed surrounded by an inflammatory infiltrate rich in cells delimited by a connective fiber tissue ring. Hematoxylin–Eosin (HE) staining, ×40.

Figure 10

Detail aspect of some residual particles of experimental graft material one month after the insertion into the realized bone cavity. Notice the large number of cells attached to their surface. HE staining, ×400.

Figure 11

Characteristic appearance of the tissue identified in control cavities left without grafting, two months after their creation highlighting the appearance of young bone tissue at the edge of the defect rich in osteoblasts with strong osteogenic activity. HE staining, ×100.

Figure 12

Overview of the appearance of the tissue that occupied the bone defect in samples from the Group A2 two months after the application of the commercial material showing the formation of new bone tissue with a characteristic honeycomb pattern. Goldner’s trichrome (GT) staining, ×40.

Figure 13

Detail image of newly formed bone tissue in the augmented bone cavities highlighting the honeycomb appearance, with osteon-like cavities still presenting residual particles of graft material in their center. GT staining, ×400.

Figure 14

The appearance of the newly formed bone tissue in a sample from Group B2 presenting the characteristic honeycomb appearance, but with a denser structure and showing a greater number of residual graft material particles. GT staining, ×40.