Primary stability of self-drilling and self-tapping mini-implant in tibia of diabetes-induced rabbits

Abstract

Objective. This study aimed to evaluate effects of type 1 diabetes mellitus and mini-implant placement method on the primary stability of mini-implants by comparing mechanical stability and microstructural/histological differences. Methods. After 4 weeks of diabetic induction, 48 mini-implants (24 self-tapping and 24 self-drilling implants) were placed on the tibia of 6 diabetic and 6 normal rabbits. After 4 weeks, the rabbits were sacrificed. Insertion torque, removal torque, insertion energy, and removal energy were measured with a surgical engine on 8 rabbits. Remaining 4 rabbits were analyzed by microcomputed tomography (micro-CT) and bone histomorphometry. Results. Total insertion energy was higher in self-drilling groups than self-tapping groups in both control and diabetic groups. Diabetic groups had more trabecular separation in bone marrow than the control groups in both SD and ST groups. Micro-CT analysis showed deterioration of bone quality in tibia especially in bone marrow of diabetic rabbits. However, there was no statistically significant correlation between self-drilling and self-tapping group for the remaining measurements in both control and diabetic groups. Conclusions. Type 1 diabetes mellitus and placement method of mini-implant did not affect primary stability of mini-implants.

Figure 1

Orthodontic mini-implant used for this study. The size is 1.6 mm at the neck and 1.5 mm at the apex in external diameter and 6 mm in length (Jin-E Screw, Jin Biomed Co., Bucheon, Korea).

Figure 2

Orthodontic mini-implants implanted in rabbit tibia. (a) Predrilling for the self-tapping mini-implant was perfomed. (b) Self-tapping mini-implant was placed into the hole. (c), (d) Self-drilling mini-implant was placed into the bone without predrilling.

Figure 3

3D micro-CT images of bone microarchitecture determined by the volume of interest (VOI). (a) Cortical bone area in control group. (b) Bone marrow area in control group. (c) Cortical bone area in diabetic group. (d) Bone marrow area in diabetic group.

Figure 4

Histologic measurements. (a) Bone to implant contact, the percentage of linear surface of the implant directly contacted by mineralized bone (BIC%). (b) Bone density, the percentage of mineralized bone over the total tissue volume (BV/TV%).

Figure 5

(a) Average body weights of alloxan-induced diabetic rabbit throughout the 8-week experimental period. (b) Blood glucose levels of alloxan-induced diabetic rabbit throughout the 8-week experimental period.