Dental Implants in head and neck tumor patients: outcome and treatment modalities as risk factors for implant failures

Abstract

BACKGROUND AND PURPOSE: Quality of life of head and neck tumor patients with mutilating resection defects is improved if dental implants are applied for oral rehabilitation after the surgical reconstruction of bone and soft tissue defects. However, if the treatment plan application includes dental implants many of the health insurance companies deny this type of oral rehabilitation, obstructing an improved quality of life for head and neck tumor patients. Therefore, the aim of the study was to determine the efficacy of dental implants inserted in head and neck tumor patients by estimating the implant survival rates and to identify treatment modalities as risk factors for implant failure. PATIENTS AND METHODS: All tumor patients were treated by the same team of head and neck surgeons. Dental implant planning and dental rehabilitation has been performed by the same prosthodontist (St.S.) since 1999, according to a defined dental treatment protocol. Implants were placed in two stages after the resection defect was surgically corrected with soft tissue and/or bone tissue. All implants were inserted in two phases, applying the submerged technique. The head and neck tumor patients have been followed up in an oncology recall system as well as in a dental recall system. In regular annual control appointments periodontal parameters at all implants were assessed. Implant failure (uncensored) was defined as (1) explantation, (2) loss of osseointegration and (3) failed use for prosthetic reconstruction. Data were coded in Excel and analyzed with SPSS 20. Descriptive statistics such as relative frequencies were computed. Overall and Kaplan-Meier survival analysis combined with a Log rank test were applied. These analyses were computed at the implant level. As there may be several implants inside one patient, the date set is prone to clumping. Consequently, an appropriate survival analysis adjusting for clumping was applied within Stata Version 12. Results of statistical analysis with p-value smaller than 0.05 were considered to be statistical significant. RESULTS: There were 322 dental implants evaluated in 71 cancer patients. 62 out of 322 implants failed (19.3%). The 8-year overall survival rate was 80.2% (± 3.1% Std.Err). The co-variables (1) radiotherapy, (2) type of radiotherapy (3-DCRT vs. IMRT), (3) type of bone tissue reconstruction (non-microvascular vs. microvascular anastomized free bone transplant) and (4) type of implant surface influenced significantly the survival of implants (Log rank, Mantel-Cox: P-value< 0.05). CONCLUSIONS. If considering the clinical challenge to rehabilitate successfully a compromised head and neck tumor patient, the 8-year implant survival rate was surprisingly high. These results proves the efficacy of dental implant treatment for those health insurance companies, obstructing treatment plan approval for oral rehabilitation. Head and neck tumor patients undergoing more demanding and costly medical treatments such as (1) the intensity-modulated radiotherapy (IMRT) and (2) the surgical reconstruction with microvascular anastomized flaps showed significantly higher implant survival rates.