IADR Abstract Archives
Factors effecting primary stability of mini-implants in vitro
Objectives: Mini-implants or Temporary Anchoring Devices (TAD) are now routinely used in orthodontic treatments; however, compared to conventional implants, TADs suffer higher failure. Achieving primary stability (PS) appears to be the most important factor predicting success of TADs. Factors such as implant diameter, length, and bone quality are known to influence PS in conventional implants; however, little is known of the effects of these factors on PS in TADs. Therefore the aim of this study was to investigate the effect of TAD’s diameter, length and the presence of cortical bone in PS.
Methods: AbsoAnchor TAD design from Dentos with 1.5,1.7, and 2mm diameters; 6,8, and 10mm length were placed in Polyurethane bone blocks (Sawbones) with densities of cancelous bone (GP-20). TADs were also placed in similar blocks that were sandwiched with either 1, or 2mm polyurethane sheets, which simulated cortical bone density. Four TADs in each group were placed using recommended procedures. PS of TADs were measured with Periotest and Osstell by two testers. Results were analysed by multifactorial ANOVA to detect the significant influence of each factor in TADs’ PS (p ≤ 0.05).
Results: Both Osstell and Periotest indicated significant increase in PS (p<0.05) when cortical bone sheet of 1 or 2 mm thickness were in contact with TADs. TADs diameter also appeared to have significant influence in PS, indicating that TADs with wider diameter (1.7-2mm) had significantly higher PS (p<0.05) in both cancelous and cortical sandwiched models. There was no significant difference in PS when different lengths of TADs were used in both cancelous and cortical sandwiched models.
Conclusions: Important factors in achieving PS in TADs appear to be bone type and implant diameter and not its length. Recognizing factors improving PS would be expected to decrease unnecessary trauma and failure rate in children and adolescence who are main recipients of TADs.
Methods: AbsoAnchor TAD design from Dentos with 1.5,1.7, and 2mm diameters; 6,8, and 10mm length were placed in Polyurethane bone blocks (Sawbones) with densities of cancelous bone (GP-20). TADs were also placed in similar blocks that were sandwiched with either 1, or 2mm polyurethane sheets, which simulated cortical bone density. Four TADs in each group were placed using recommended procedures. PS of TADs were measured with Periotest and Osstell by two testers. Results were analysed by multifactorial ANOVA to detect the significant influence of each factor in TADs’ PS (p ≤ 0.05).
Results: Both Osstell and Periotest indicated significant increase in PS (p<0.05) when cortical bone sheet of 1 or 2 mm thickness were in contact with TADs. TADs diameter also appeared to have significant influence in PS, indicating that TADs with wider diameter (1.7-2mm) had significantly higher PS (p<0.05) in both cancelous and cortical sandwiched models. There was no significant difference in PS when different lengths of TADs were used in both cancelous and cortical sandwiched models.
Conclusions: Important factors in achieving PS in TADs appear to be bone type and implant diameter and not its length. Recognizing factors improving PS would be expected to decrease unnecessary trauma and failure rate in children and adolescence who are main recipients of TADs.