Complications

Augmentation procedures are technique sensitive and require a high level of expertise in order to avoid intra and post-operative complications.

General intra-operative complications that pertain to all grafting procedures such as hemorrhage, nerve damage, inability to obtain adequate graft or place implant with good stability can be avoided by thorough understanding of anatomy and use of advanced diagnostic procedures for treatment planning. The paragraphs below will highlight specific complications related to above mentioned techniques.

Common complications resulting from additive bone augmentation procedures are lesser than expected bone gain, soft tissue complications, and implant loss. ^63-65

Autogenous block grafts, in particular, have been known to have a high resorption rate, at times resulting in inadequate bone volume. Corticocancellous blocks, such as those harvested from the hip or symphysis may demonstrate resorption of up to 60% of the initial volume within the first 6 months.⁶⁶ However, studies have shown with the use of a membrane, these resorptive changes may be minimized.⁶⁶ In addition, if the block graft is not adequately fixated, it will lead to fibrous tissue formation between the graft and the recipient bed, ultimately resulting in loss of the graft.⁶⁷ Allogenic block grafts, when compared with autogenous block grafts, have a higher rate of complications including soft tissue dehiscence, incision line opening, exposure of graft, partial or total loss of graft, and infection.^35,36 With advancing three dimensional computer assisted surgical planning and matching of the graft to defect morphology, surgical time and post-operative complications may be reduced.^36,

When performing guided bone regenerative procedures, soft tissue complications which include dehiscence, membrane exposure, and infections/abscess may result, occurring at a rate of about 16.8%.⁶³ Membrane exposure can occur as early as 1 week or as late as 6 months.⁶³ There appears to be no difference between resorbable and non-resorbable membrane exposures.⁶³ However, if membranes are exposed, there is a 3 times less likely gain in bone than in non-exposed sites.⁶⁴ When an exposure occurs, the presentation is usually in the form of swelling, pain, inflammation, suppuration, or it could even be asymptomatic.⁶³ The membrane is usually removed, especially if it is non resorbable; in this case the entire site will be cleaned, and the procedure may be re-attempted.⁶⁵ Exposed resorbable membranes may remain; frequent follow ups may be necessary to ensure proper healing. In addition, antibiotics or Peridex rinses may be prescribed post operatively to minimize the risk of infection.⁶⁵

When performing procedures that modify the existing bone volume different complications may arise. For example, crestal bone resorption surrounding implants may occur following ridge expansion/splitting techniques if the blood supply is diminished to the surrounding area.^40,67 This is more likely to occur if the ridge is less than 3 mm in thickness.^40,67Other common complications include lack of implant primary stability, and partial or complete fracture of the bone segment.³⁶ With reduced ridge thickness, Ella et al,⁶⁸ found that 3 mm fractures in the crests of the buccal wall occurred in 43% of cases.

Adverse outcomes related to alveolar distraction osteogenesis include incomplete distraction, fracture of the device, relapse of the bone gained, or early resorption of the bony segment, infection, wound dehiscence, or nerve injury.^67,69 These complications arise in as many as 75% of cases.⁶⁷ Moreover, severe vertical deficiency of the mandible is a risk factor for neural damage or mandibular fracture; therefore, at least a height of 3 mm is necessary for the segment to be distracted.⁶⁹ Specific to this technique, the distracted segment of bone may be displaced lingually/palatally due to improper trajectory and/or pull of attached mucosa/periosteum.⁶⁷ A secondary grafting procedure may be necessary in order to attain adequate dimensions of bone for successful implant placement.⁶⁷

Understanding the factors that may lead to post-operative complications are imperative for prevention of complications and their effective management if they occur.