engleski

Predictive value of biomechanical factors for primary stabilitiy of manually inserted orthodontic microimplants

Objectives: The aim of this study was to explore the predictive value of biomechanical factors: implant design, cortical bone thickness, and implantation forces and torques, for primary stability of manually inserted orthodontic microimplants. Materials and methods: Experiment included 60 orthodontic microimplants of three different manufactures: The Aahrus system® (Medicon EG, Tuttlingen, Germany), Dual top® (Jeil Medical Corp., Seul, Korea) and Ortho Easy® (Forestadent, Pforzheim, Germany). The implants thread length were 6 mm and 8 mm. Thread diameter and tissue collar length were 1.5 and 1.5 mm (Aarhus), 1.6 and 1.5 mm (Dual top), and 1.7 and 2 mm (Ortho Easy). Implants were inserted in bone samples 2x1 cm of sternal part of swine ribs placed in a specially designed device made for three-dimensional measurement of forces and torques (Croatian Institute of Civil Engineering, Zagreb, Croatia). The implants were manually inserted using long driver shaft and standard handle. No pilot hole was made. The measurements of implantation vertical forces (N) and torques (Nmm) were recorded using Picoscope (Pico Technology Ltd, St Neots, UK). Periotest M (Medizintechnik Gulden, Modautal, Germany) device was used for assessment of primary stability. Multiple logistic regression analysis was used for statistical analysis. Results: Most significant factors for lower primary stability of manually placed mini-implants are thin cortical bone (p=0.032) and longer tissue collar length (p=0.032) while narrower thread diameter had borderline significance (p=0.052). Parameters regarding mini-implant thread length, vertical force and torque variations as well as trend of vertical force and torque changing during the time of insertion were not significant predictors for primary stability. Conclusions: Thick cortical bone, shorter tissue collar length and a wider thread diamater have the higest predictive value for good primary stabilitiy of manually inserted orthodontic microimplants.

orthodontic microimplants; primary stability

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