Influence of surgical technique, implant shape and diameter on the primary stability in cancellous bone

Achievement of primary stability during surgical placement of dental implants is one of the most important factors for successful osseointegration depending on various anatomical, surgical and implant-related factors. Resonance frequency analysis (RFA) has been shown as a non-invasive and objective technique for measuring the stability of implants. The aim of this study was to evaluate the effect of some surgical and implant-related factors in enhancing primary stability and to estimate a correlation between RFA and insertion torque (IT) in proximal regions of cow ribs representing cancellous bone. Fifteen implant beds were prepared in the most proximal region of six fresh cow ribs. Ninety implants with three different shapes and two different diameters were placed with two different surgical techniques, and the primary stability was compared using RFA and IT. Significantly higher RFA and IT values were achieved when under-dimensioned drilling was used as the surgical method (P < 0 01); significantly higher IT values were obtained with the use of wider implants (P < 0 01) and partially conical Astra Tech implants showed the highest IT values (P < 0 01). When all the implants were considered, significant correlations between the IT and RFA values were noted (% 40 6, P < 0 05). Partially conical implants with a wide diameter to be placed with the modified surgical technique proposed appear to be useful in enhancing the primary stability in cancellous bone

Biomechanical analysis of cervical multilevel oblique corpectomy: an in vitro study in sheep

Background. Anterolateral oblique corpectomy is an alternative approach to treatment of multilevel cervical spinal disease. It is stated that the approach does not cause instability in the patients with hard discs, so fusion or instrumentation is not required. The authors undertook a study on stability of the cervical spine by an animal model to establish if this approach causes instability

A comparison of single- versus double-row suture anchor techniques in a simulated repair of the rotator cuff - An experimental study in rabbits

We compared time-dependent changes in the biomechanical properties of single- and double-row repair of a simulated acute tear of the rotator cuff in rabbits to determine the effect of the fixation techniques on the healing process

In vitro investigation of heat transfer in calf spinal cord during polymethylmethacrylate application for vertebral body reconstruction

The objective of this experimental study was to investigate the temperature variations within the spinal cord of calf cadavers during polymethlymethacrylate (PMMA) application for vertebral body reconstruction. Cervical spines including the cervical spinal cord of ten fresh cadavers were used. Corpectomy and laminectomy were performed and dura was exposed at the same level for proper placement of thermal sensors. Sensors were placed in multiple holes in the spinal cord at depths of 3, 6, 9 and 12 mm, respectively. Whether the thermal sensors were placed in the gray or white matter was determined by computerized tomography. The white and gray matters of the spinal cord exhibited different thermal properties. The white matter was more conductive and absorbed less heat than the gray matter. The heat sensor nearest to PMMA exhibited temperatures of 42-44 degrees C. The second heat sensor placed at 9 mm depth within the gray matter showed 44 degrees C. The third sensor, which was placed at 6 mm depth within the spinal cord recorded the same temperature as the first, i.e., nearest to PMMA sensor. The fourth heat sensor, which was at the farthest location from PMMA demonstrated 37-39 degrees C. The temperature distribution within the gray matter was inversely proportional to the distance from the heat source. The temperature at the dorsal white matter, which was distant from the heating source, remained nearly constant and was not elevated. Our data suggest that thermal injury to the spinal cord during PMMA application may be expected to be more significant in the gray matter when compared with other neural tissues

Time-dependent changes in failure loads of 3 biceps tenodesis techniques - In vivo study in a sheep model

Background: Failure load of the tendon-fixation material-bone unit has a crucial importance for the rehabilitation protocol after tenodesis procedures