Effects of Glycemic Control in Patients with Type II Diabetes Mellitus on Dental Implant Survival

Poor glycemic control in patients with diabetes mellitus (DM) has long been considered a contraindication for dental implant therapy due to the increased risk of delayed healing, infection, and microvascular/macrovascular complications. Numerous animal and human studies have also suggested poor glycemic control as a contraindication to dental implant therapy. However, recent studies have assessed implant stability over the initial four to six months after implant placement in patients with Type II DM possessing HbA_1C levels as high as 12% and reported high rates of implant survival regardless of the patients’ level of glycemic control. Although these results are promising, the studies were of a short duration and primarily assessed implant-related outcomes prior to restoration of the implants. In contrast to these studies, the goal of our study was to assess the effects of elevated glycemic levels on post-loaded dental implant survival.

We conducted a retrospective review of patients who completed dental implant therapy at a single institution from January 2013 through December 2015. Only patients who received stage I implant placement with delayed loading and documented HbA_1C values obtained within 3-months pre- or postoperatively were included in our study. These values reflect the average level of glycemic control over 60-90 days, representing the critical time period for bone metabolism, healing and osseointegration. Additional inclusion criteria included a follow-up assessment of the restored dental implant at least 1-year post-implant placement and at least 6-months post-loading. We defined loading as implants restored with either a single-unit crown, multi-unit fixed partial denture, or a removable overdenture. We defined survival as an implant lacking any signs of clinical mobility or failure of the implant to osseointegrate, pain, infection, or periimplant radiolucency.

Our study consisted a total of 42 male patients with 173 implants (83 maxillary, 90 mandibular). HbA_1C levels ranged from 5.5 to 12.2%. At the time of implant placement, 27 patients (102 implants) in group 1 had no history of DM (and/or HbA_1C ≤ 5.9%), 10 patients (47 implants) in group 2 had well-controlled DM (HbA_1C 6-8%) and 5 patients (24 implants) in group 3 had poorly-controlled DM (HbA_1C ≥ 8.1%). There were a total of five implant failures (2.89%), with three implant failures (three patients) in group 1, two implant failures (one patient) in group 2, and zero implant failures in group 3. We found no statistically significant difference in the number of implant failures among the three groups (p = 0.42). We also found no statistically significant difference in the percentage of implant failures among the three groups (p = 0.34).

Patients with poorly controlled DM are typically not considered appropriate candidates for dental implant therapy. However, recent studies demonstrate that the effects of hyperglycemia on implant therapy remain uncertain. Although further investigation of longer-term effects of elevated HbA_1C levels is warranted, the results of our study demonstrate favorable outcomes for post-loaded dental implant survival in patients with HbA_1C levels as high as 12.2%. The clinical results of our study are consistent with those of previous studies, which reported similar rates of implant survival in patients with Type II DM and elevated HbA_1C levels.

References:

1. Dowell S, Oates Jr TW, Robinson M: Implant success in people with type 2 diabetes mellitus with varying glycemic control: A pilot study. J Am Dent Assoc 138:355–361, 2007.
2. Oates Jr TW, Galloway P, Alexander P, Vargas Green A, Huynh-Ba G, Feine J, McMahan CA. The effects of elevated hemoglobin A_1c in patients with type 2 diabetes mellitus on dental implants: Survival and stability at one year. J Am Dent Assoc 145:1218–26, 2014.