Estimation of Distances within Real and Virtual Dental Models as a Function of Task Complexity

Orthodontists have seen their practices evolve from estimating distances on plaster models to estimating distances on non-immersive virtual models. However, if the estimation of distance using real models can generate errors (compared to the real distance measured using tools), which remains acceptable from a clinical point of view, is this also the case for distance estimation performed on digital models? To answer this question, 50 orthodontists (31 women and 19 men) with an average age of 36 years (σ = 12.84; min = 23; max = 63) participated in an experiment consisting of estimating 3 types of distances (mandibular crowding, inter-canine distance, and inter-molar distance) on 6 dental models, including 3 real and 3 virtual models. Moreover, these models were of three different levels of complexity (easy, medium, and difficult). The results showed that, overall, the distances were overestimated (compared to the distance measured using an instrument) regardless of the situation (estimates on real or virtual models), but this overestimation was greater for the virtual models than for the real models. In addition, the mental load associated with the estimation tasks was considered by practitioners to be greater for the estimation tasks performed virtually compared to the same tasks performed on plaster models. Finally, when the estimation task was more complex, the number of estimation errors decreased in both the real and virtual situations, which could be related to the greater number of therapeutic issues associated with more complex models

Zoster after Cyclophosphamide for Systemic Lupus Erythematosus or Vasculitis: Incidence, Risk Factors, and Effect of Antiviral Prophylaxis

International audienceObjective: To assess the incidence and the risk factors for zoster in patients exposed to intravenous cyclophosphamide (CYC) for systemic vasculitis or systemic lupus erythematosus (SLE), as well as the protective effect of prophylaxis by valacyclovir (VCV).Methods: This retrospective study included all adults treated by intravenous CYC for SLE or systemic vasculitis between 2011 and 2015 at Toulouse University Hospital, France. Zoster occurrence was recorded using medical chart review, laboratory data, and patient interviews. Univariate Cox models were computed to assess the risk factors for zoster and the protective effect of prophylaxis by VCV.Results: The cohort consisted of 110 patients (81 systemic vasculitis and 29 SLE). During a mean followup of 3.4 years after CYC initiation, 10 cases of zoster occurred, leading to an overall incidence of 27.9/1000 patient-years (95% CI 15.2-50.6); it was 59.4/1000 patients (95% CI 27.5-123.6) during the year after CYC initiation. Four patients experienced persistent postherpetic neuralgia. Probable risk factors were lymphopenia < 500/µl at CYC initiation (HR 5.11, 95% CI 0.94-27.93) and female sex (HR 4.36, 95% CI 0.51-37.31). The incidence was higher in patients with SLE (HR as compared with systemic vasculitis patients = 2.68, 95% CI 0.54-13.26). None of the 19 patients exposed to VCV during the followup developed zoster.Conclusion: The incidence of zoster is high in systemic vasculitis and in patients with SLE exposed to intravenous CYC. CYC may favor postherpetic neuralgia. Prophylaxis by VCV should be considered, particularly in cases of lymphopenia < 500/µl at CYC initiation and during the year after