A review of clinical outcomes associated With dental implant treatment performed by residents in advanced training programs at the University of Minnesota School of Dentistry

Abstract

Purpose: The central focus of this retrospective chart review is the comparison of survival rates for dental implants placed by residents in Oral and Maxillofacial Surgery and Graduate Periodontics in coordination with restorative treatment provided by residents in Graduate Prosthodontics at the University of Minnesota School of Dentistry. Materials and Methods: Records for 246 patients treated at the University of Minnesota School of Dentistry, Minneapolis, Minnesota between 1994 and 2008 met the inclusion criteria for this study. Potential records were initially identified using an existing database maintained by the school’s Implant Program that contains dates, record numbers, implant types, and departmental affiliations of the restorative and surgical clinicians who planned the implant surgeries. A total of 968 patients with 2,591 implants in this database had a resident in Graduate Prosthodontics listed as the restorative clinician and a resident associated with either Oral and Maxillofacial Surgery or Graduate Periodontics listed as the surgical clinician. The 246 records in this review were selected based on the patient having a recorded visit to any department in the School of Dentistry within the last 12 months. Approval for this review was obtained through the Institutional Review Board. The principle investigator performed a manual review of the patient records and collected data relating to implant survival, grafting, restoration survival, and technical complications. Statistical analysis was performed by consultants from the Biostatistical Design and Analysis Center. Results: A final total of 228 patients and 707 implants were available for analysis. The exclusion of 17 charts was based on final implant placement being performed by faculty or restorative work provided by faculty or dental students. A total of 39 failures were observed in 29 patients. The 5-year survival rate for all implants observed in this study was 95.3%, which includes failures due to implant fracture (0.99%). Oral and Maxillofacial Surgery residents treated 106 patients with 329 implants and a 5-year survival rate of 95.4%. Graduate Periodontics residents treated 134 patients with 378 implants and a 5- year survival rate of 96.9%. Survival rates for both departments were calculated without failures due to implant fracture. Accepting a threshold value for significance of p<0.05, Cox Proportional Hazards Regression demonstrated no significant difference in survival rates between the two departments as the pvalues obtained were 0.59 when all failures were included and 0.4 when failures due to fracture were excluded. Prosthetic utilization of the implants included single crowns (49.65%), fixed partial dental prostheses (23.76%), mandibular fixed complete dental prostheses (9.90%), maxillary removable complete dental prostheses with implant supported fixed bars (6.65%), mandibular removable complete dental prostheses with implant supported fixed bars (3.54%), two-implant retained mandibular removable complete dentures (1.42%), and other restoration designs (2.69%). Seventeen sites (2.40%) were not restored with implant support as planned. The 5 year survival rates for single crowns (SC 83%) and fixed partial dental prostheses (FPD 89%) were obtained using life table analysis. The 5 year complication rates included luting cement fracture (SC 14%, FPD 47%), screw loosening (SC 12%, FPD 5%), screw fracture (SC 3%, FPD 2%), and porcelain fracture (SC 5%, FPD 1%). Complication and failure counts were provided for the remaining prosthetic types. Conclusions: Within the limitations of this review, and in light of results found in similar studies, the 5 year survival rate of 95.3% for all dental implants placed by residents in Oral and Maxillofacial Surgery and Graduate Periodontics at the University of Minnesota School of Dentistry further demonstrates that satisfactory and predictable survival outcomes can be achieved by clinicians at this level of training. Statistical analysis revealed no significant differences in survival based only on the departmental affiliation of residents placing the implants. Residents in Graduate Prosthodontics provided the restorations for these implants; however, the 5 year survival and complication rates for the restorations were further removed from corresponding values established in the dental literature. This may have proceeded from the inclusion criteria for this review that selected charts having dental school visits within the last 12 months. The unexpected variances in the restoration survival and complication rates warrant further investigation and demonstrate the long term treatment information that must be communicated to patients as part of their planning and consent process. Implant survival rates alone do not adequately summarize clinical outcomes.