A medicolegal perspective on dental implants and bone grafting
For patients with missing teeth, dental implants offer an effective replacement, and the results of the procedure are generally very predictable and successful. Despite this, some dental implants do fail, at a rate of around 5% in the lower jaw and 10% in the upper jaw. Failure in the first few months following implantation is relatively rare; conversely, some implants fail after several years, due to peri-implant disease. However, many patients are not made aware of this, or of the fact that even successful implants have a finite lifespan, usually in the region of 15 years, and, contrary to the usual assumption, will not last a lifetime.
A patient’s suitability for dental implantation depends on many factors, including their general state of health, smoking history, oral health, the quality and size of the bone into which the implant will be inserted, and the amount of space available in the jaw. Thus, visual examination and X-rays of the mouth, as well as information collected from the patient, should be used to assess patient suitability. A failure to do so may result in serious complications or implant failure.
The insertion of an implant is an invasive procedure: the dentist drills a hole into the patient’s jawbone, into which the implant is placed. As the bone heals, it fuses with the implant in a process known as osseointegration. If the bone and implant fail to fuse, the implant can become loose and ultimately fail. Infection at the site of the implant can also cause loosening, or the jawbone may be of insufficient quality to secure the implant. Bone loss can be caused by a number of factors, including prolonged tooth loss, tumour and cyst removal, periodontal disease, and trauma. In such cases, a bone graft may be needed to repair the damaged area and allow the placement of implants.
Bone grafting is relatively common and is used in around 60% of all dental implant procedures. Although not as successful as implants into native bone, implants into grafted bone have a success rate of around 80% after 10 years. Numerous materials are available for use, and each has advantages and drawbacks. Autogenous bone grafts are taken from the patient and may be harvested from intraoral sites, such as the curved portion of the mandible, or from sites outside the mouth, usually the iliac crest. The major disadvantages of this type of graft stem from the bone harvesting procedure, particularly morbidity associated with the donor site. Extra-oral harvesting sites are associated with an increased risk of complications and pain levels compared to sites within the mouth.
Allografts consist of bone taken from human donors, who may be living or deceased, and were developed to overcome the issues surrounding availability and morbidity associated with autogenous grafts. As the two types of graft have similar physicochemical properties, and clinical outcomes are comparable, allografts may be a good option where an autogenous graft is not possible. Synthetic materials, including polymers, bio-ceramics and composite biomaterials are also available.
Whichever type of graft is chosen, there is a risk of complications, which is increased by the patient’s age, a positive smoking history and a history of periodontitis. Complications are also more likely in bone defects that require more than one implant. The most common complication is wound breakdown, caused by a failure of the wound to heal properly. This leads to exposure of the graft and is often followed by contamination of the graft or surrounding membranes. Ultimately, the graft often fails. The incidence of this complication is influenced by the objective of the graft and the use of a barrier membrane, which allows only cells with bone-producing properties to fill the defect. Infections may be introduced during the surgical procedure or arise due to exposure of the wound to the oral environment. Management of this type of complication depends on the extent of the wound breakdown, the amount of graft exposure and the presence of a concurrent infection.
Other complications include generalized infections, bone fractures, graft encapsulation by soft tissues and neural damage. Prevention of complications should focus initially on controlling any patient-related risk factors that may be present. In particular, active periodontal disease must be managed before surgery takes place. As well as determining any relevant anatomical landmarks in the implant site, the donor site should be carefully assessed to determine whether it will offer sufficient bone volume to repair the defect. The risk of bone fractures can be reduced by identifying the location of the basal bone. The use of computer-guided surgical techniques when harvesting bone grafts from the mandible can help to avoid neural damage.
Dental implants offer a long-term and aesthetically pleasing solution to the problem of missing teeth. However, inserting them carries the risk of complications and implant failure. In order to manage expectations, patients need to be made aware of this. Careful patient selection, including a comprehensive oral examination and x-rays, a thorough assessment of potential bone harvesting sites, control of patient-related risk factors, and adherence to good surgical techniques can all help to reduce these risks, and thus the potential for litigation.
Further reading:
Donkiewicz, P., Benz, K., Kloss-Brandstätter, A., & Jackowski, J. (2021). Survival Rates of Dental Implants in Autogenous and Allogeneic Bone Blocks: A Systematic Review. Medicina (Kaunas, Lithuania), 57(12), 1388. https://doi.org/10.3390/medicina57121388
Sanz-Sánchez, I, Sanz-Martín, I, Ortiz-Vigón, A, Molina, A, Sanz, M. Complications in bone-grafting procedures: Classification and management. Periodontol 2000. 2022; 88: 86– 102. doi:10.1111/prd.12413
