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Onlay Grafts in Pre-Implant Surgery

Banner_Onlay Grafts in Pre-Implant Surgery

Tooth loss is systematically accompanied by alveolar bone loss

Therefore, implant placement often requires a prior bone volume augmentation step. Many surgical techniques exist, including the onlay graft. The procedure and protocol .



The onlay bone graft procedure

This surgical technique, described in 20th century literature, consists of applying an autologous or heterologous bone graft to the bone defect to be restored using an osteosynthesis screw.



The objective of the technique is to replace enough volume in the bone crest for placement of dental implants, respecting the 5 mm rule, by bone block fixation. The bone block may be autologous (harvested from the recipient patient) or heterologous (source other than the recipient: human, animal or synthetic) in origin.



  • Significant bone gain,
  • Vertical and horizontal gains possible.



  • Residual bone required for graft fixation,
  • Prolonged operative time due to time required for block adaptation.


Factors for success for onlay bone grafts

The success of a bone graft depends partly on the surgical technique used, but this is not the only consideration. For onlay grafts, the following points apply:


Preparation of the recipient site

The recipient site is the entry point for healing of the graft and must bleed so that the graft is rapidly saturated with blood. This step can be completed in several ways, notably by:

  • Making small holes using a pointer,
  • Gently “stroking” the surface of the bone with a spherical disk cutter for mild decortication,
  • Scarifying the bone surface with a disk cutter.


Adaptation and preparation of the bone graft

Healing of a bone graft always occurs via establishment of a fibrin network to ensure good graft stability. This is assured via establishment of neovascularisation and integration of the bone block. The three essential steps for satisfactory preparation are as follows:

  • Adaptation of the graft to the recipient site using a bone disk cutter. This step may be omitted if a custom graft completed using the patient’s DICOM files is used,
  • Preparation of osteosynthesis screw holes,
  • Preparation of notches for the screw heads.


Closure of soft tissues without tension

A sufficient volume of residual bone is required at the site for graft fixation. Pay attention to the interradicular spaces for the fixation screws.



  • Rehydration of the block for 5 to 10 min (0.9% sodium chloride),
  • Opening of site/flap detachment,
  • Adaptation of the plate at the recipient site (rapid rotation bone disk cutter with irrigation),
    • Objective: closest possible plate/recipient site contact,
    • Pay attention to the graft angles,
  • Decortication of the recipient site (spherical disk cutter) or cortical perforation (drill): blood clot,
  • Positioning of the graft and placement of the osteosynthesis screw,
  • Dissection of the periosteum (light scalpel slices inside the flap): elasticity of the soft tissues,
  • Suturing of the flap without tension: watch out for perioperative oedema as the soft tissues swell.