Complications after mandibular implant surgery

Although any surgery has a long list of complications, the incidence of problems following chin augmentation is generally low and they are almost always temporary. When complications do occur, they are usually easily treated and, for a more appropriate implant selection or at the patient's request, the surgery can always be repeated and the implant replaced to better meet the patient and surgeon's expectations.

Literature data show that infection after alloimplantation develops in 4-5% of cases. However, the incidence of infectious complications is reduced by the intraoperative use of gentamicin solution to soak the implant and wash the created pocket. Hematomas are very rare. Extended mandibular implants do not cause asymmetry unless the pocket is made over the mental foramina.

Sensory disturbances, usually temporary, are observed in 20-30% of patients with chin implants. Hypoesthesia is expected and patients should be warned about it before surgery. Extended implants are much more likely to cause sensory disturbances than central chin implants, but this should not be a reason not to use extended implants. They do not migrate or get pushed out. Skin necrosis with external access is rare.

Bone resorption under chin implants has been reported since the 1960s, but no significant clinical consequences have been identified. Implants placed too high above the pogonion promote erosion of the thinner cortical bone in this area. Resorption of the thicker compact bone of the mental protrusion and pogonion is less important, including clinically. Long mandibular implants, due to their placement under the mental foramina, do not migrate upward, and muscle attachments prevent them from moving downward, ensuring ideal stability at the desired level. Softer cast Silac-tic implants promote less bone resorption than dense implants. Larger implants may cause greater resorption due to greater tension between the periosteum, muscle, and cortical bone. Absorption occurs during the first 6-12 months and stops on its own if the implant is placed correctly. It is possible that some resorption may even stabilize the implant over the following years. The soft tissue profile of the chin remains stable despite this process. It is not accompanied by pain or tooth decay. If the implant is removed, the area of bone resorption may regenerate.

Occasionally, there is a visible or palpable protrusion of the most lateral part of the elongated implants, probably due to the increase in volume due to the formation of a capsule contracting the free ends of the implant. This applies especially to the thinnest, very flexible edges of the elongated anatomical chin implants. Often, massaging these edges helps to stretch the capsule and eliminates the palpable protrusion, making it clinically insignificant. Rarely, implant removal, pocket expansion, and implant repositioning are required. Protrusion due to capsule contraction often occurs after 6 weeks.

Muscle damage or swelling of the lower lip may cause changes that are noticeable when smiling but not noticeable at rest. The lower lip portion may appear weaker because it does not retract downward as far as the lateral portions due to temporary damage to the depressor muscles. This is more common after intraoral access.

Although asymmetry does not develop after proper implant placement, it may become apparent postoperatively due to inadequate preoperative planning in the presence of an initially asymmetric mandible. Any asymmetry should be discussed with patients preoperatively so that they understand that any postoperative asymmetry is a result of the preoperative condition and not caused by the implant or the implant placement technique. A very small number of patients experience temporary speech impairment, usually a lisp, due to swelling or dissection of the depressor labii muscles. This effect on the depressor and mentalis muscles, combined with hypoesthesia, may occasionally result in temporary drooling and mild slurring of speech. Injury to the branches of the motor nerve of the mandibular border is rare and temporary. The natural postoperative clefts or pits in the chin may change slightly after surgery. Although the above list of potential problems is long, actual experience is limited to hypoesthesia and bone resorption, while other complications are rare and temporary.

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