Bone Graft Before an Implant: Why and How

A bone graft before an implant involves rebuilding the volume of jawbone when it has become insufficient to anchor an artificial root stably. It is proposed when the examination, in particular the Cone Beam scan, shows a bone height or thickness below what the implant requires. It is neither routine nor trivial: it is a surgical procedure in its own right, with precise indications, several techniques and after-effects to anticipate. This article explains why bone is lacking, how it is rebuilt, what can realistically be expected from healing, and which factors influence the outcome.

# Why does the jawbone shrink after a tooth is lost?

As long as a tooth is in place, its root stimulates the surrounding bone and maintains it. When the tooth is extracted or lost, that stimulation disappears and the alveolar bone, the bone that formed the socket, resorbs.

This loss is measurable. According to the systematic review by Tan and colleagues, published in Clinical Oral Implants Research in 2012, at six months an average horizontal loss of about 3.79 mm is observed, that is 29 to 63% of the thickness, along with an average vertical loss of about 1.2 mm on the buccal side, that is 11 to 22% of the height. Most of it occurs during the first three to six months following the extraction.

In practical terms, the longer you wait after losing a tooth, the greater the risk of running short of bone. This does not mean that a graft is always necessary, but it explains why it sometimes is. When bone is genuinely lacking, several strategies exist and grafting is only one of them; the options are detailed in our article on dental implants when there is not enough bone.

# When is a bone graft indicated before an implant?

Grafting is discussed when the bone volume does not allow an implant to be placed in a correct position with sufficient initial stability. The following situations are common.

• A ridge too thin to fully surround the implant.
• Insufficient bone height, particularly in the posterior maxilla where the sinus descends.
• A localized defect following an old extraction, a cyst or an infection.
• Bone loss related to advanced periodontal disease.

In the posterior maxilla, a lack of height beneath the sinus calls for a specific technique, sinus floor augmentation, covered in our dedicated article on sinus augmentation, or sinus lift.

Grafting is not the only possible answer. In some cases, shorter or tilted implants, a different site, or a different prosthesis may be chosen. This nuance matters: the Cochrane review by Esposito and colleagues (2009) points out that vertical augmentations are associated with more complications than the placement of short implants. The choice is made case by case, after an assessment.

# What are the types of dental bone graft material?

There are four families of graft material, and not two as simplified presentations sometimes suggest. The ITI consensus (4th conference, 2008) indicates that these materials may be used alone or in combination, safely and predictably.

# The autograft, the biological reference

Autogenous bone, harvested from the patients themselves, for example from the jaw, has the best biological properties because it brings living cells with it. Its limitation is that it requires a second surgical site, and therefore additional morbidity.

# Allografts, xenografts and synthetic materials

Allogeneic, xenogeneic and alloplastic grafts avoid this second site. They mainly serve as a support, a scaffold that the body gradually colonizes with its own bone. Their resorption rate and their behavior differ from one material to another, which guides the choice according to the defect to be treated.

One point deserves clarification: the CE marking of a biomaterial is a regulatory conformity for placing it on the market, not proof of clinical efficacy nor a guarantee of results. The predictability of augmentation techniques rests on consensus data, not on a commercial label.

# What is guided bone regeneration and the role of the membrane?

Guided bone regeneration, or GBR, is a technique that aims to rebuild bone beyond the existing contour. According to the ITI consensus (2008), it combines particulate autogenous bone, an allograft, a xenograft or a combination of these materials, in order to regenerate the bone located above the ridge.

The membrane is the element often associated with GBR. Its role is to maintain the space and to prevent the soft tissues, which heal faster, from invading the area intended for bone. It is a principle of tissue separation.

A point of clinical honesty is called for: the membrane is not systematic. The ITI consensus specifies, for onlay grafts, that coverage with a slowly resorbing material, with or without a membrane, may be indicated to limit resorption. The membrane is therefore a conditional option, decided according to the type of defect, and not a mandatory step.

# How does a dental bone graft procedure work?

The procedure is carried out under local anesthesia, in sterile conditions, as described by the ITI consensus. The general sequence includes accessing the area, preparing the recipient site, placing the graft and possibly a membrane, then closing.

Two approaches exist as to when the implant is placed.

• Simultaneous approach, one stage. The implant is placed at the same time as the graft, when the residual bone allows sufficient primary stability to be achieved.
• Staged approach, two stages. The graft is performed first, healing is allowed to take place, then the implant is placed. The ITI consensus favors delayed placement for onlay grafts.

The full course of the implant phase, once the bone has been rebuilt, is described in our article on dental implants in Kénitra.

# Choukroun’s PRF as an adjunct

PRF, platelet-rich fibrin following the Choukroun protocol, is an autologous concentrate obtained from a blood sample taken from the patient, then centrifuged. It releases factors that support healing and it can be combined with the graft.

Its value should be presented with measure. The meta-analysis by Alrayyes and Al-Jasser, published in Tissue Engineering and Regenerative Medicine in 2022, found a benefit of PRF compared with no graft in socket preservation, but a smaller effect than that of conventional graft materials. The best results came from PRF mixed with a graft material. The authors call for larger randomized trials to confirm this. PRF is therefore a useful adjunct whose evidence is still limited, not a superior bone substitute.

# How long does healing take after a bone graft?

There is no single timeframe that applies to everyone. Healing depends on the type of graft, the site, the volume rebuilt and the approach chosen.

In practice, the range is wide. In the Cochrane review by Esposito and colleagues (2009), the healing periods before implant placement or exposure run from about three to six months for the simplest augmentations, around six to seven months for certain guided bone regeneration procedures, and up to eight to nine months, or even longer, for the most extensive onlay grafts. Sinus floor augmentations may likewise require several months. When primary stability is sufficient, simultaneous placement shortens the overall pathway.

Presenting a fixed timeframe for every situation would be inaccurate. The best estimate is the one given for your own case, after reading the Cone Beam scan and choosing the technique.

# What can be expected in terms of reliability?

No numerical success rate should be put forward for a given practice: that would be a misleading argument. What the data allow us to say is qualitative. According to the ITI consensus (2008), the survival of implants placed after grafting is similar to that obtained in native bone for sinus elevation and for the ridge-splitting technique, and slightly lower for onlay grafts. Reliability therefore depends on the technique, and not on a uniform percentage.

# What are the risk factors and contraindications?

A bone graft is not a procedure without after-effects. Nuance is part of honest information.

# Post-operative discomfort is real

The Cochrane review by Esposito and colleagues (2009) documents post-operative morbidity: infections, dehiscences, transient sensory disturbances. For vertical augmentations, the risk of complications was markedly higher, with an odds ratio of 4.97 in their analysis, and one trial reported that 85% of patients experienced severe pain for more than a week. The authors specify that these conclusions rest on few trials and on low certainty. That is nonetheless enough to rule out the word painless: the procedure is performed without pain thanks to the anesthesia, but the recovery calls for painkillers and a little patience.

# Smoking

Smoking is a major risk factor. Chen and colleagues (PLOS One, 2013) report a relative risk of implant failure of 1.92 in smokers, with a 95% confidence interval of 1.67 to 2.21. Mustapha, Salame and Chrcanovic (Medicina, 2021) found an increased failure risk of about 140% and marginal bone loss greater by 0.58 mm. Stopping smoking before and after the procedure is one of the most useful levers for supporting healing.

# Diabetes

Diabetes must be assessed and brought under control, but without excessive alarm. In the open data from Chen and colleagues (2013), no significant association between diabetes and implant failure was demonstrated across the studies analyzed. The distinction that matters is the one between controlled and uncontrolled diabetes: unstable blood sugar impairs healing. It is therefore a factor to stabilize beforehand, rather than an absolute contraindication.

# Other factors

Oral hygiene, the condition of the gums and the control of any periodontal disease also shape the outcome. Active periodontitis must be treated before any surgery; to tell simple inflammation from a deeper condition, see our article on the difference between periodontitis and gingivitis. After placement, monitoring remains important, as explained in our article on the signs of implant failure and peri-implantitis.

# The equipment used to plan and perform the graft

The precision of a graft depends first of all on the analysis of the bone volume. At the practice, in Kénitra, the Durr Dental Cone Beam scan makes it possible to measure the available bone height and thickness in three dimensions, and to identify the structures to be respected, such as the sinus or the nerve. The surgery takes place in the operating room, and piezosurgery allows bone work that is gentle on the soft tissues. Choukroun’s PRF can be prepared from a blood sample so that it can be combined with the graft when this is relevant. This equipment does not guarantee an outcome on its own; it serves rigorous planning and well-controlled surgery.

# In summary

A bone graft before an implant answers a real lack of bone, documented by the examination. It relies on four families of graft material, sometimes combined with guided bone regeneration and a membrane when this is indicated. Healing generally takes several months, within a range that depends on the case. The benefits are established, but the after-effects and the risk factors, particularly smoking, must be taken into account. Honest information is worth more than a promise: the right decision is built after a precise assessment and a discussion of the options.