In vitro comparison of primary stability of two implant designs in D3 bone

BACKGROUND Primary stability (PS) is a key factor for implant survival rate and depends on implant design or bone quality. The aim of this study was to compare different thread designs implants, evaluating PS with periotest values (PV) and implant stability quotient (ISQ) values through resonance frequency analysis (RFA). MATERIAL AND METHODS A total of 60 implants (Radhex®, Inmet-Garnick S.A., Guadalajara, Spain) were placed in freshly bovine ribs in vitro. Two designs were used: 30 tapered body with single thread design (PHI) and 30 tapered body with double thread design implants (PHIA). Both designs were 4mm wide and 12mm long. Implants were placed according to manufacturer's guidelines. Osstell™ and Periotest® devices were used to evaluate PS by a blinded independent observer. Computed tomographies (CTs) of the ribs were made (BrightSpeed Series CT systems, GE Healthcare, Milwaukee, WI, USA) and bone quality surrounding each implant was evaluated in Hounsfield Units (HU) using Ez3D Plus software (Vatech Co., Korea). Bone quality was classified according to Misch and Kircos in D1, D2, D3 or D4. RESULTS All implants were mechanically stable. Only implants placed in D3 bone (350-850 HU) were selected for the study: 28 PHI and 26 PHIA. The one way ANOVA showed significant difference (p < 0.005) among two implants designs in ISQ values (61,55 ± 6,67 in PHI and 68,94 ± 5,82 in PHIA). No significant difference (p = 0,171) was shown in PV between two designs (-4,47 ± 1,39 in PHI and -4,77 ± 0,87 in PHIA). CONCLUSIONS Higher PS was found using Osstell™ device in implants with double thread design (PHIA) in comparison to implants with single thread design (PHI) in D3 bone.