# Effects of Magnetic Stimulation on Dental Implant Osseointegration: A Scoping Review
## 3 Results
### In Vivo Studies  
#### 3.2.1 Static Magnetic Fields from Permanent Magnets  
Six studies investigated the effect of SFM on implant osseointegration in vivo: one in rats, four in rabbits, and one in dogs. In addition to in vitro results, [PERSON] et al. [31] also reported a positive effect of moderate SMF on histologically evaluated osteogenesis and osteointegration of the 3D-printed Ti scaffolds implanted in mandibular rats.  
[PERSON] et al. [46] demonstrated that Ti implants receiving SFM from a magnetic cover screw (Neodymium magnet generating a magnetism of 15 mT) showed a higher mean percentage of bone-to-implant contact (BIC) than the control groups at all investigated time-points (1, 4 and 8 weeks) and improved peri-implant bone formation in rabbits. Furthermore, by using microarrays the authors found an upregulation of 293 gene transcripts of the 20,000 analyzed, many of which have been described as participating in bone formation, angiogenesis and ECM-deposition processes. Moreover, the SFM-induced transcripts also included genes related to osteoclasts and bone resorption, highlighting very puzzling and sometimes contrasting effects of SFM in the formation and maintenance of bone around dental implants.  
Further studies confirmed the BIC increase after SFM exposure at 15 and 30 days [45] and at 12 weeks [44], respectively. In the study by [PERSON] et al. [45], dental implants inserted in the tibia of New Zealand rabbits after SFM stimulation showed a higher BIC both in the earlier and in the later osseointegration period, supporting the ability of SFM to reduce the bone healing period. [PERSON] et al. used similar implants placed into rabbit femurs and confirmed a faster osseointegration by measuring BIC after 12 weeks of healing. In fact BIC values were significantly higher in the test group compared to the controls (32.4 \(\pm\) 16.6% and 17.1 \(\pm\) 4.5%, respectively) [44].  
Some benefits in the use of static magnetism were reported by [PERSON] et al. [47] when studying the osseointegration of commercial sandblasted/large-grit/acid-etched-treated Ti implants inserted in rabbit tibia with or without a neodymium magnet on the cover screw. Indeed, the SFM was shown to increase BIC in implants just after 3 weeks, although at longer times (6 weeks) BIC values remained almost unchanged, both in the test and control groups.  
The only in vivo study evaluating the effects of SFM in the jawbone was performed by [PERSON] et al. [43] on dogs. The authors designed a Ti implant with sand-blasted surfaces and with a magnet inside (mTi) able to generate a moderate SFM (0.3-9.4 mT middle position and 0.2-1.4 mT upper-lower position within 5 mm from the implant), avoiding the use of a fixed external magnetic source. The effect of a filling of superparamagnetic hydroxyapatite (HYH-Fe) added directly around the implant was also evaluated. Thus, Ti + hydroxyapatite (HA), mTi + HA and mTi + superparamagnetic hydroxyapatite (HYH-Fe) implants were inserted into the jawbone of two dogs and the formation of new bone was evaluated both by histological analysis and by sequential fluorescent labeling at 8 and 12 weeks. This preliminary study reported increased trabecular bone formation around mTi implants with HYH-Fe compared to the other tested combinations.