RESUMEN
PURPOSE: To investigate the influence of crown material (lithium-disilicate, 3Y-TZP zirconia) and abutment type (rigid implant, resin tooth with artificial periodontium) on wear performance of their antagonist teeth and adjacent teeth. MATERIALS AND METHODS: A mandibular left first molar (#36) with adjacent human teeth (mandibular left second premolar: #35, mandibular left second molar: #37) and antagonistic human teeth (maxillary left second premolar: #25, maxillary left first molar: #26, maxillary left second molar: #27) was prepared simulating a section of the jaw. Samples were made with extracted human molars (Reference), crowned implants (Implant), or crowned resin tooth analogues (Tooth). Crowns (tooth #36; n = 16/material) were milled from lithium-disilicate (Li, IPS e.max CAD) or 3Y-TZP zirconia (Zr, IPS e.max ZirCAD, both Ivoclar Vivadent). Thermal cycling and mechanical loading (TCML) in the chewing simulator were applied simulating 15 years of clinical service. Wear traces were analyzed (frequency [n], depth [µm]) and evaluated using scanning electron pictures. Wear results were compared by one-way-ANOVA and post-hoc-Bonferroni (α = 0.05). RESULTS: After TCML, no visible wear traces were found on Zr. Li showed more wear traces (n = 30-31) than the reference (n = 21). Antagonistic teeth #26 showed more wear traces in contact to both ceramics (n = 27-29) than to the reference (n = 21). Strong wear traces (> 350 µm) on antagonists and their adjacent teeth were found only in crowned groups. Abutment type influenced number and depth of wear facets on the antagonistic and adjacent teeth. CONCLUSION: The clinically relevant model with human antagonistic and adjacent teeth allowed for a limited comparison of the wear situation. The total number of wear traces and strong wear on crowns, antagonistic and adjacent teeth were influenced by crown material.
RESUMEN
STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To examine the differences in the use of the methylprednisolone protocol for traumatic spinal cord injury before and after the publication of new guidelines in Switzerland. SUMMARY OF BACKGROUND DATA: The use of the methylprednisolone protocol for traumatic spinal cord injury changed after the publication of new guidelines. The rate of physicians prescribing high-dose methylprednisolone for patients with acute spinal cord injury was studied. Two intervals, each comprising 24 months before and after the publication of the consensus article in Switzerland, were compared. As a secondary parameter, the neurological development during the rehabilitation period was compared. METHODS: The charts of all adult patients who were referred for treatment of a spine or spinal cord injury during the periods from April 2001 to March 2003 and from April 2008 to March 2010 were retrospectively reviewed for demographic and medical details, the application of methylprednisolone within the first 48 hours after the injury, the diagnoses at the time of their referral, and the diagnosis at the time of hospital discharge. Classification of traumatic spinal cord injury was made according to the guidelines of the American Spinal Injury Association. Neurological improvement concerning the level of injury was defined as a change of this segment to a more caudal one or a complete normalization of sensory and motor function. RESULTS: During the 2 study periods, 110 patients (2001-2003) and 116 patients (2008-2010) were included. Between 2001 and 2003, 96% of patients with a neurological deficit after spinal cord injury were treated with high-dose methylprednisolone, whereas this rate dropped to 23% during the second time interval. In both treatment periods, neurological improvement during the rehabilitation period (mean: 6 mo) did not differ significantly. Pooled data of all patients with a neurological deficit in both study periods (n = 159) showed improved neurological levels in 32% of patients treated with methylprednisolone and 28% of patients without this therapy, without a statistical difference between the groups. CONCLUSION: In Switzerland, the acceptance of the guidelines for treating traumatic spinal cord injury with high-dose methylprednisolone has been extremely high in the past. The use of high-dose methylprednisolone has decreased to a much lower level in Switzerland after the publication of new guidelines, which is comparable to various other countries. Despite these changes, no differences in the neurological outcome were detected between the observed patient populations.