Effect of miniscrew placement torque on resistance to miniscrew movement under load.
ABSTRACT The primary stability of orthodontic anchorage miniscrews is believed to result from mechanical interlock, with success based upon a number of variables, including screw diameter, angle of placement, monocortical vs bicortical placement, placement through attached or unattached soft tissue, presence or absence of a pilot hole, periscrew inflammation, and maximum placement torque. The purpose of this ex-vivo study was to further explore the relationship between maximum placement torque during miniscrew placement and miniscrew resistance to movement under load.
Ninety-six titanium screws were placed into 24 hemi-maxillae and 24 hemi-mandibles from cadavers between the first and second premolars by using a digital torque screwdriver. All screws were subjected to a force parallel to the occlusal plane, pulling mesially until the miniscrews were displaced by 0.6 mm. The Spearman rank correlation test was used to evaluate whether there was an increasing or a decreasing relationship between maximum placement torque of the screws, miniscrew resistance to movement, and bone thickness. A paired-sample t test and the nonparametric Wilcoxon signed rank test were used to compare maximum placement torque, bone thickness, and miniscrew resistance to movement between coronally positioned and apically positioned screws in the maxilla and the mandible, and between screws placed in the maxilla vs screws placed in the mandible. Additionally, 1-way analysis of variance (ANOVA) with the post-hoc Tukey-Kramer test was used to determine whether there was a significant difference in miniscrew resistance to movement for screws placed with maximum torque of <5 Ncm, 5 to 10 Ncm, and >10 Ncm.
The mean difference in miniscrew resistance to movement between maximum placement torque groupings, <5 Ncm, 5 to 10 Ncm, and >10 Ncm, increased throughout the deflection range of 0.0 to 0.6 mm. As deflection increased to 0.12 to 0.33 mm, the mean resistance to movement for miniscrews with maximum placement torque of 5 to 10 Ncm was statistically greater than for screws with maximum placement torque <5 Ncm (P <0.05). As deflection increased to 0.34 to 0.60 mm, the mean resistance to movement for miniscrews with maximum placement torque of 5 to 10 Ncm and >10 Ncm was significantly greater than for screws with maximum placement torque <5 Ncm (P <0.05). At no deflection was there a significant difference in resistance to movement between the 2 miniscrew groups with higher placement torque values of 5 to 10 Ncm and >10 Ncm.
Ex vivo, the mean resistance to movement of miniscrews with higher maximum placement torque was greater than the resistance to movement of those with lower maximum placement torque.
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ABSTRACT: Since some patients with psoriatic arthritis do not respond to typical drug treatments, alternatives are needed. Findings suggest that interleukins 12 and 23 might affect clinical symptoms and pathological joint changes of psoriatic arthritis. Ustekinumab is a human monoclonal antibody that inhibits receptor-binding of these cytokines. We aimed to assess the efficacy and safety of ustekinumab for psoriatic arthritis in this phase II study. We undertook a double-blind, randomised, placebo-controlled, crossover study at 24 sites in North America and Europe. Patients with active psoriatic arthritis were randomly allocated via interactive voice response system to either ustekinumab (90 mg or 63 mg) every week for 4 weeks (weeks 0-3) followed by placebo at weeks 12 and 16 (n=76; Group 1) or placebo (weeks 0-3) and ustekinumab (63 mg) at weeks 12 and 16 (n=70; Group 2). The first 12 weeks of the study were placebo-controlled. Masking was maintained to week 16, and patients were followed up to week 36 [corrected]. The primary endpoint was ACR20 response at week 12. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00267956. At week 12, 32 (42%) patients in Group 1 and ten (14%) in Group 2 achieved the primary endpoint (difference 28% [95% CI 14.0-41.6]; p=0.0002). Of 124 (85%) participants with psoriasis affecting 3% or more body surface area, 33 of 63 (52%) in Group 1 and three of 55 (5%) in Group 2 had a 75% or greater improvement in psoriasis area and severity index score at week 12 (47% [33.2-60.6]; p<0.0001). During the placebo-controlled period (weeks 0-12), adverse events arose in 46 (61%) patients in Group 1 and 44 (63%) in Group 2; serious adverse events were recorded in three (4%) Group 2 patients (none in Group 1). Ustekinumab significantly reduced signs and symptoms of psoriatic arthritis and diminished skin lesions compared with placebo, and the drug was well tolerated. Larger and longer term studies are needed to further characterise ustekinumab efficacy and safety for treatment of psoriatic arthritis.The Lancet 02/2009; 373(9664):633-40. · 39.06 Impact Factor
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ABSTRACT: Ustekinumab, a human monoclonal antibody against interleukins 12 and 23, has shown therapeutic potential for psoriasis. This study assessed the efficacy and safety of ustekinumab in psoriasis patients and assessed dosing intensification in partial responders. In this multicentre, phase III, double-blind, placebo-controlled study, 1230 patients with moderate-to-severe psoriasis (defined by a psoriasis area and severity index [PASI] score > or =12, and at least 10% total body surface area involvement) were randomly assigned to receive ustekinumab 45 mg (n=409) or 90 mg (n=411) at weeks 0 and 4, then every 12 weeks, or placebo (n=410). Partial responders (ie, patients achieving > or =50% but <75% improvement from baseline in PASI) were re-randomised at week 28 to continue dosing every 12 weeks or escalate to dosing every 8 weeks. Both randomisations were done with a minimisation method via a centralised interactive voice response. The primary endpoint was the proportion of patients achieving at least 75% improvement in PASI (PASI 75) at week 12. Analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00307437. All randomised patients were included in the efficacy analysis. 273 (66.7%) patients receiving ustekinumab 45 mg, 311 (75.7%) receiving ustekinumab 90 mg, and 15 (3.7%) receiving placebo achieved the primary endpoint (difference in response rate 63.1%, 95% CI 58.2-68.0, p<0.0001 for the 45 mg group vs placebo and 72.0%, 67.5-76.5, p<0.0001 for the 90 mg group vs placebo). More partial responders at week 28 who received ustekinumab 90 mg every 8 weeks achieved PASI 75 at week 52 than did those who continued to receive the same dose every 12 weeks (22 [68.8%] vs 11 [33.3%]; difference in response rate 35.4%, 95% CI 12.7-58.1, p=0.004). There was no such response to changes in dosing intensity in partial responders treated with ustekinumab 45 mg. During the placebo-controlled phase, 217 (53.1%) patients in the 45 mg group, 197 (47.9%) in the 90 mg group, and 204 (49.8%) in the placebo group experienced adverse events; serious adverse events were seen in eight (2.0%) patients in the 45 mg group, five (1.2%) in the 90 mg group, and eight (2.0%) in the placebo group. Although treatment with ustekinumab every 12 weeks is effective for most patients with moderate-to-severe psoriasis, intensification of dosing to once every 8 weeks with ustekinumab 90 mg might be necessary to elicit a full response in patients who only partially respond to the initial regimen.The Lancet 05/2008; 371(9625):1675-84. · 39.06 Impact Factor