7 Complications Following Implant-Prosthetic Rehabilitations in Edentulous Patients
P. Casentini, D. Wismeijer, M. Chiapasco, G.O. Gallucci
Implant treatment of edentulous patients has become a proven and very predictable treatment option. However, complications associated with implant treatment are not rare. Such complications cannot always be avoided, even if the clinician is well-trained and experienced; nor can long-term biological and mechanical complications always be predicted. For this reason, inserting implants implies the necessity of a strict aftercare regime. After the superstructure has been inserted, patients are expected to report back for periodic inspection of the peri-implant tissues and the superstructure itself. Once the clinician has evaluated the patient and a steady state has been reached, an individual patient-based recall regime can be installed. Systematic and continuous monitoring of the condition of the peri-implant tissues for disease is recommended. Implant superstructures also require continuous monitoring on an individual schedule. The following clinical and radiographic parameters should be evaluated at recall visits:
Plaque and calculus
Bone loss (probing)
Wear of occlusal surface
Abutment status (with the superstructure removed)
Regular monitoring of the peri-implant tissues is strongly recommended to facilitate early diagnosis of any peri-implant disease. Plaque and calculus must be removed, and sometimes patients will have to be remotivated. Bleeding on probing is evaluated, and probing depths around implants are recorded. Bone loss can be evaluated by probing and the evaluation of periapical radiographs. Such radiographs must be taken every two years, since bone loss can proceed rapidly even in apparently healthy patients. A routine recall visit of a patient treated with an implant-supported overdenture is presented in Figs 1a-f.
The main types of complications are:
Failure of the retentive system
Fracture of the dental prosthesis
Bone loss due to peri-implant infection
Bone loss due to overload or absence of a passive fit
Complications due to insufficient planning
Implants supporting overdentures must be surrounded by a cuff of keratinized tissue. While its presence may have little influence on the long-term prognosis of the implants, it does seem to play an important role for patient comfort. As described in Chapter 3, the absence of keratinized tissue can result in peri-implant pain, which can adversely affect the patient’s oral hygiene and in the long term even lead to the destruction of soft and hard tissues around the implants (Figs 2a-b and 3a-b). The treatment plan must therefore provide for inserting the implants such that the keratinized tissue heals in contact with the implants or keratinized tissue is in place after a grafting procedure. Hence, if no keratinized tissue is present, surgical correction by means of a tissue graft is often required (Fig 4a-g).
Soft-tissue hyperplasia is sometimes observed beneath overdentures. There are several possible explanations for this phenomenon, including insufficient oral hygiene and insufficient space between the bar and tissue. A comprehensive treatment approach is based primarily on plaque control (Figs 5a-b). In some cases, however, the tissue will have to be reduced surgically and the design of the superstructure modified to prevent recurrence.
The design of a superstructure must always allow for adequate dental hygiene. The dental technician must design the superstructure to facilitate access with standard oral-hygiene tools. Sufficient interimplant distance must also be ensured. The pontic areas must be based on the ovate pontic design concept, and no inaccessible concave areas must be present. A ridge-lap design must be avoided wherever possible (Figs 6, 7a-b).
Over time, the retentive devices of an overdenture will exhibit wear due to use. When clips and matrices loosen, patients will complain about a loss of retention. However, specific instruments can be used to activate the retentive devices (Figs 10a-c).
With the introduction of Locator attachments, retention has become adjustable to the patient’s needs by simply replacing the plastic matrices (Figs 11a-c).
However, there comes a time when the matrices have to be replaced. In most cases, this can be implemented by relining procedure. The matrix is removed from the denture and an impression is made of the denture-bearing area including the abutments. In the dental laboratory, the new matrices are then polymerized into the denture. The matrices must be absolutely parallel, otherwise the clips in the matrix will be bent when the denture is inserted and their retention will deteriorate rapidly. The procedure can also be performed at chairside (Figs 12a-f ). However, this is not the preferred approach, as it is very difficult to position the matrices in parallel with this procedure. There is also a risk of resin polymerizing under the matrix, making it difficult if not impossible to remove the denture without causing damage to the soft tissues or to the denture itself. This approach should only be used in an emergency.