Controlling Bone Graft Substitute Microstructure to Improve Bone Augmentation

Abstract

Vertical bone augmentation procedures are frequently carried out to allow successful placement of dental implants in otherwise atrophic ridges and represent one of the most common bone grafting procedures currently performed. Onlay autografting is one of the most prevalent and predictable techniques to achieve this; however, there are several well documented complications and drawbacks associated with it and synthetic alternatives are being sought. Monetite is a bioresorbable dicalcium phosphate with osteoconductive and osteoinductive potential that has been previously investigated for onlay bone grafting and it is routinely made by autoclaving brushite to simultaneously sterilize and phase convert. In this study, monetite disc-shaped grafts are produced by both wet and dry heating methods which alter their physical properties such as porosity, surface area, and mechanical strength. Histological observations after 12 weeks of onlay grafting on rabbit calvaria reveal higher bone volume (38%) in autoclaved monetite grafts in comparison with the dry heated monetite grafts (26%). The vertical bone height gained is similar for both the types of monetite grafts (up to 3.2 mm). However, it is observed that the augmented bone height is greater in the lateral than the medial areas of both types of monetite grafts. It is also noted that the higher porosity of autoclaved monetite grafts increases the bioresorbability, whereas the dry heated monetite grafts having lower porosity but higher surface area resorb to a significantly lesser extent. This study provides information regarding two types of monetite onlay grafts prepared with different physical properties that can be further investigated for clinical vertical bone augmentation applications.

In vitroandin vivoassessment of CaP materials for bone regenerative therapy. The role of multinucleated giant cells/osteoclasts in bone regeneration

“…Although the resorption β‐TCP phase mediated by cell phagocytosis is slower than that of dissolution of brushite, it tends to reprecipitate as insoluble HA in vivo reducing its degradation and limits replacement by new bone. The total porosity would be expected to greatly influence the total resorption of grafts by providing access to resorptive cellular components with osteoclasts and macrophages . Thus, small changes in the chemical composition could result in negative in vivo performance.…”

Natural graft tissues and synthetic biomaterials for periodontal and alveolar bone reconstructive applications: a review

“…Dicalcium phosphate dihydrate (DCPD or Brushite), has been investigated for both bone defect repair and vertical bone augmentation applications as injectable cements or as pre-set cement granules [119–121]. It has been demonstrated that injectable brushite cements are capable of regenerating bone in atrophic alveolar ridges, buccal dehiscence defects and maxillary sinus floor elevation procedures [122].…”

Differential response of human blood leukocytes to brushite, monetite, and calcium polyphosphate biomaterials

“…9,[11][12][13][14] Brushite, also known as dicalcium phosphate dihydrate (DCPD), can be synthesized as a hydraulic cement with uses in several applications. 15 Brushites have been tested with success for vertical bone augmentation, 13,[16][17][18] but they tend to re-precipitate as insoluble HA after implantation, which limits resorption and ultimately graft replacement by bone tissue. 19 Heating and dehydrating brushite cements above 60 C, 20 result in monetite biomaterials that are chemically very similar to brushite but differ in physical properties.…”