Methods: Human lower sound premolares were selected and divided into 6 groups (n=5), and stored at 37°C in a 0.5%-chloramine solution. To simulate the periodontal ligament the roots were covered with a thin layer of three types of material: (i) polyurethane elastomeric material, (ii) polyether impression material, and (iii) a A-polysiloxane soft cushion material. The teeth were embedded in an acrylic resin block (Techovit 4004, Heraeus Kulzer, Germany) simulating no and 50% bone loss, respectively. The specimens were statically subjected up to a maximum load of 30N perpendicular to the tooth axis (crosshead speed=1mm/min) in a universal material testing machine. The load-deflexion curves and periotest values were recorded. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (p= 0.05). The Pearson's correlation coefficient between the deflexion and the periotest values was calculated.
Results: The median (mm) horizontal deflexion values of the premolar crowns with no bone loss were significant higher for polyether (ii= 0.33; p= 0.008) and polysiloxane (iii= 0.15; p= 0.008) compared to polyurethan (i= 0.02). For 50% bone loss a significant higher tooth deflexion was found for specimens of group (iii) (1.08) as for group (i) (0.03; p= 0.008). All specimens with reduced bone support layered with polyether were dislocated. This deflexion displayed a significant positive correlation with the periotest values (p= 0.01).
Conclusion: It is possible to simulate physiologic tooth mobility by means of an A-polysiloxane material. Specimens are safely retented, even when reduced bone support is simulated.