## 4 Discussion
The specially designed magnetic membrane could enable its clinical application by combining the handling, adaptability, cost-effectiveness, and excellent barrier properties of the cofferdam 51-56 with the effect of static magnetic fields on the bone tissue. Magnetic fields of 750 G at the surface, 400 G at the 3 cm sides, and 900 G at the 2 cm sides in contact with the cofferdam were detected when the magnetic field was measured using the Hall-effect transducer--UGN3501U--from Allegro Microsystem Inc. Fields of 300 G were measured one millimetre from the magnetic dam at the surface, 150 G at the sides of 3 cm, and 400 Gat the sides of 2 cm. This shows that despite its small size and thickness (about 0.5 mm), the dam is capable of generating magnetic fields that can affect the surrounding tissue. The results of the in vitro experiments show the same inconsistency of results found in the current literature. According to many studies, the stimulation with SMF seems to have a negative effect on proliferating cells while leading to an increase in the rate of differentiation, activation, and mineralisation [31; 32; 33; 34]. In contrast, other studies show that SMF within a certain range of reduced magnetic intensity, on the order of mT, increases cell growth in a dose-dependent manner [35; 36]. However, given the paucity of studies on static magnetic fields and the large variability in experimental conditions, the relationship between field intensity and cellular effect in terms of proliferation or induction is still unclear. According to our results, the observed slight decrease in proliferation could be due to the high values of magnetic fields developed by the dam (400-900 G at contact, 150-400 G at 1 mm distance). Cell viability analysis performed after 24 and 72 h of contact with the magnetised dam showed no statistically significant differences in the growth of the MG63 cell population compared with the controls, demonstrating the non-toxicity of the dam. This evidence is consistent with the results of [PERSON] et al. (2004), who found an increase in GNP in the range of 300 and 800 G 128 after 24 h of cell exposure [25]. Therefore, in agreement with in vivo studies, an increase in mineralisation, bone density, and vascularisation can be assumed to be positive. This study has some limitations, mainly due to its innovative design, which limits the comparability of our results with other studies. In addition, biological changes due to the presence of a magnetic field were not investigated by alkaline phosphatase analysis. Mild or negligible cytotoxicity was found in cells exposed to coated or recycled magnets; although no exposure of magnet grains to cell culture was observed, it cannot be excluded as a microscopical leakage. When the magnets are not in direct contact with gingival fibroblast cells, there was no significant difference in the cell shape or surface structure, even in areas with a high magnetic field density and steep gradient [30]. This laboratory study is one of the first studies on the application of static magnetic fields in GBR. The use of a magnetic membrane would make it possible to shorten the physiological time of bone healing that is required: 4-6 months. Since the goal of this surgical method is often the placement of osseointegrated implants, a magnetic membrane would allow us to shorten the time required for the morphofunctional restoration of one or more tooth elements, thus significantly improving the patient's quality of life.