Onlay grafts can provide predictable increases in bone volume when used for alveolar ridge augmentation. However, it is important that the graft is rigidly fixated to the recipient site.
In the tenting technique, specialized Titanium screws are commonly used, as tenting screws, to provide rigid fixation for the grafting. As noted in a study, “Tenting of the periosteum and soft tissue matrix with titanium screws maintains space and minimizes resorption of mineralized particulate allograft.”1. A prior study 2, evaluated the effectiveness of the tenting technique using intraoral cortical block grafts with particulate human mineralized allograft, and concluded that, “Tenting of the periosteum and soft tissue matrix using a cortical bone block maintains space and minimizes resorption of the particulate allograft volume.” 2
Cortical bone repositioning (CBR), as described in a newer study 3, represents another innovation on earlier techniques. It is performed by cutting out a cortical bone block from the original surface, and fixating the new block laterally with titanium screws. The procedure was reported to have been done on 7 patients, and 16 implants were placed. Prior to the procedure, the bone width in the defect area was 3.28 mm. 4-Months after cortical bone repositioning, the bone width was measured again in the same area, and it was 6.46 mm. The researchers concluded that the: “CBR technique is a simple procedure without the use of any biomaterials or devices. The main advantage of this technique in comparison to autogenous grafts is the lack of donor site issues. This technique has the possibility of inducing the patient’s regenerative ability for bone healing.” 3 This result is not surprising, in that it confirms the other studies mentioned above that these kinds of techniques can offer predictable reconstruction of large defects by using either autogenous bone or a combination of autogenous and particulate.
What has been your experience with cortical block grafts?
1. J Oral Maxillofac Surg. 2010 Feb;68(2):428-35. Screw “tent-pole” grafting technique for reconstruction of large vertical alveolar ridge defects using human mineralized allograft for implant site preparation. Le B et al.
2. Implant Dent. 2008 Mar;17(1):40-50. Cortical tenting grafting technique in the severely atrophic alveolar ridge for implant site preparation.Le B et al.
3. Int J Periodontics Restorative Dent. 2018 September/October;38(5):691–697 Cortical Bone Repositioning Technique for Horizontal Alveolar Bone Augmentation: A Case Series. Yamauchi K et al.