Time effect of whole body vibration on peri-implant bone healing

Objectives: A previous study indicated a stimulating effect of low-magnitude high-frequency loading, applied through whole body vibration (WBV), on peri-implant bone healing (Clinical Oral Implants Research, in press). The aim of this study was to evaluate the effect of time factors, namely load duration and of the implementation of rest periods, on peri-implant bone healing. Methods: A custom-made titanium implant was inserted in the medioproximal site of one tibia of 95 rats and was left to heal for 1 or 4 weeks. The daily WBV consisted of 15 consecutive frequency steps (12, 20, 30, … , 150 Hz) at an acceleration of 0.3 g. The number of the applied loading cycles were determined by the duration of the loading. The rats were divided into 5 groups with different loading times: 0 (control/non-loading), 1.25, 2.5, 5 and twice 1.25 minutes (with an interim recovery period) of loading. Bone-to-implant contact (BIC) and peri-implant bone fraction (BF) in 3 regions of interest (ROIs) were measured (figure 1) on polymethylmethacrylate sections stained with Stevenel's bleu and picrofushin red. Statistical analyses were done using two-way ANOVA and the Tukey HSD test. The level of significance was set at p < 0.05. Results: BIC of every loaded group was significantly higher than that of the unloaded control group for both healing periods (figure 2a). In the 4-week healing group, BIC and BF (in all ROIs) were significantly higher in case of twice 1.25 minutes of loading compared to no loading or 1 time of 1.25 minutes of loading. Conclusion: Time of loading significantly influenced the effect of the WBV on peri-implant bone healing. Twice 1.25 minutes of loading appears to have the most favorable effect. Low-magnitude high-frequency loading, applied through WBV, with a particular time sequence can stimulate peri-implant bone healing and bone formation.