Cementitis and Implant Failure

As we resolve the major reasons for implant failure, we need to look for the less frequent causes of implant failure in order to approach 100% success over time. Residual cement is one of those less frequent but very real causes for implant failure. The implant pictured below exhibited gradual bone loss over time until the implant was lost. The apparent diagnosis was peri-implantitis. Peri-implantitis is possibly one of the most over-diagnosed diseases of the human body. Any bone loss around an implant is diagnosed as peri-implantitis which is grossly inaccurate, and this routine misdiagnosis leads to ineffective treatment and increased reimplantation failures.
This implant was diagnosed with peri-implantitis. Multiple treatments to control the bacterial infection failed. Upon removal, the initial etiology was found to be retained cement.

The cements used to retain implant crowns are classified by the FDA as dental adhesives. Dental adhesives are materials that are used to bond dental materials to each other and they are not intended to contact viable tissues. As a result, the FDA does not require vigorous testing for biocompatibility. However, some crown cements have been tested for cytotoxicity and genotoxicity by the manufacturer and this should be a question dentists ask of any cement manufacturer before the cement is used on their patient. The inflammation caused by cement toxicity can cause not only gingival inflammation but also marginal bone loss. Of course, if the initial gingival inflammation and marginal bone loss associated with cement toxicity persists, a secondary bacterial infection will evolve and develop into peri-implantitis. Being able to differentiate between cementitis and peri-implantitis with early intervention can lead to a complete resolution of the disease process. The following case illustrates the effort put into providing excellent patient case to have it compromised by cementitis. The following case also provides a mechanism of early accurate diagnosis of cementitis and the regeneration of lost tissue.
The first molar is unrestorable. Long narrow roots indicate a complicated extraction.
Troughing was needed with the removal of structure to gain access with elevators. The majority of troughing is into the tooth rather than the bone.
Elevation of the roots still resulted in fracture of the distal root as noted by the retained root tip.
Further troughing resulted in significant removal of the interradicular bone. Buccal and lingual full thickness flaps were elevated with incisions into the attached gingiva and a membrane is placed to assist in keeping saliva out of the socket during grafting.
The socket is grafted with Socket Graft Injectable.
The membrane is folded over the graft material.
Day of extraction and graft.
Day of grafting. A sutureless membrane technique was used. The membrane was secured with Oral Bond. The membrane was exposed, but the mixing of Oral Bond with bleeding obscures the membrane from view.
Two weeks post extraction. The membrane is secure and still covered with Oral Bond.
Two weeks post extraction. Mineralization can now be seen within a few millimeters of the crest. The patient is scheduled for implant placement 4 weeks after extraction.
4 weeks after extraction, day of implant placement. While the crestal tissue is soft, incipient mineralization has occurred throughout the socket. At this time, the highest number of active osteoblasts are present, making this an ideal time for implant placement. The membrane is removed and the implant is placed without flaps or incisions.
4 weeks after extraction, day of implant placement. The implant is placed approximately 2 mm below the original crest. The original crest is obvious on the mesial of the molar. The mineralization will continue to the top of the original crest.
4 weeks after implant placement. At this time, mineralization has progressed to the level of the original crest. The patient is scheduled for healing abutment placement 8 weeks after implant placement.
8 weeks post implant placement day of healing abutment. The patient is referred for restoration.
The healing abutment is in place. Note the retention of gingival tissue. The sutureless technique and early implant placement maintains the gingival volume.
Two months after healing abutment and 8 days after cementation. The patient presents with significant swelling and inflammation of the buccal gingiva.
Evaluation of the radiograph shows approximately 2 mm of bone loss on the mesial of the implant.
Closer inspection shows mesial bone loss, but also cement on the mesial surface of the restoration.
The abutment and crown were curetted, removing significant cement. Because the crown has only been in place for 8 days, peri-implantitis was ruled out. It takes longer than 8 days for bacteria to organize and initiate bone loss. Therefore, the diagnosis of cementitis was made. Cementitis is a toxic response of the gingiva producing inflammation resulting in bone loss without bacteria. Because this was deemed to not be an infection, only cement removal was deemed necessary. No irrigation, antibiotics, or debridement of the implant surface was performed.
Four months after removal of cement, the gingiva was healthy.
The radiograph shows regeneration of the mesial marginal bone loss.
Closer inspection shows removal of all retained cement and bone at ideal levels.

In our practice, all patients are recalled by the implant surgeon within one month after completion of the prosthetic restorations. The appointment is designed to identify any condition that will prevent the implant from functioning for a lifetime. Future articles will outline the items evaluated at this “what could cause this implant to fail” appointment.


American Society for Bone and Mineral Research (ASBMR)

Tissue Engineering and Regenerative Medicine International Society (TERMIS)