Impact of implant thread design on insertion torque and osseointegration: a preclinical model.

BACKGROUND: Successful osseointegration of endosteal dental implants has been attributed to implant design, including the macro-, micro- and nano- geometric properties. Based on current literature pertaining to implant design, the resultant cellular and bone healing response is unknown when the thread thickness of the implants is increased, resulting in an increased contact area in implants designed with healing chambers. The aim of this study was to evaluate the effect of two implant designs with different thread profiles on the osseointegration parameters and implant stability at 3- and 6-weeks in vivo using a well-established preclinical dog model. MATERIAL AND METHODS: A total of 48 type V Ti alloy implants were divided in two groups according to their thread design (D1= +0.1x/mm and D2= +0.15x/mm) and placed in an interpolated fashion into the radii of six beagles. Insertion torque was measured at time of placement, radii were extracted for histological processing following 3- and 6-week healing intervals. Histologic and histomorphometric analyses were performed in terms of bone to implant contact (%BIC) and bone area fraction occupancy within implant threads (%BAFO). Statistical analyses were performed through a linear mixed model with fixed factors of time and implant thread design. RESULTS: Surface roughness analysis demonstrated no significant differences in Sa and Sq between D1 and D2 implant designs, which confirmed that both implant designs were homogenous except for their respective thread profiles. For insertion torque, statistically significant lower values were recorded for D1 in comparison to D2 (59.6 ± 11.1 and 78.9 ± 10.1 N⋅cm, respectively). Furthermore, there were no significant differences with respect to histological analysis and histomorphometric parameters, between D1 and D2 at both time points. CONCLUSIONS: Both thread profiles presented equivalent potential to successfully osseointegrate in the osteotomies, with D2 yielding higher mechanical retention upon placement without detrimental bone resorption.

[Comparative clinical study of the effects of vecuronium and suxamethonium during oto-rhino-laryngeal and tracheobronchial laser surgery]. / Etude clinique comparative des effets du vécuronium et du suxaméthonium au cours des chirurgies oto-rhino-laryngologique et trachéo-bronchique par laser.

52 patients selected at random were assigned to four groups according to the surgery and muscle relaxant used: vecuronium (group A) and suxamethonium (group B) in ENT, vecuronium (group C) and suxamethonium (group D) for laser surgery. The first dose of vecuronium was 0.05 mg X kg-1, followed by repeat doses of 0.0125 mg X kg-1; suxamethonium was first given in a dose of 1 mg X kg-1, this being followed by a drip of 3 mg X kg-1. The anaesthetic protocol was the same for all groups. The results showed a shorter onset of action with suxamethonium (group A: 210 +/- 30 s, group B: 75 +/- 15 s, group C: 200 +/- 50 s, group D: 80 +/- 20 s) and a similar duration of action for the initial doses of the two drugs (group A: 9 +/- 3 min, group B: 6 +/- 3 min, group C: 11 +/- 4 min, group D: 7 +/- 2 min). Continuing the muscle relaxation proved easier with the suxamethonium; signs of decurarization occurred rather unexpectedly with vecuronium. No adverse effect was seen with vecuronium, whilst the diastolic blood pressure rose 20% during the first 25 min following the administration of suxamethonium. It can be concluded that, in the absence of monitoring of the curarization, the repeated administration of vecuronium with a first dose of 0.05 mg X kg-1 brought few advantages compared with the continuous infusion of suxamethonium.