A sinister subject: Quantifying handedness‐based recruitment biases in current neuroimaging research

Approximately ten per cent of humans are left‐handed or ambidextrous (adextral). It has been suggested that, despite their sizable representation at the whole‐population level, this demographic is largely avoided by researchers within the neuroimaging community. To date, however, no formal effort has been made to quantify the extent to which adextrals are excluded from neuroimaging‐based research. Here, we aimed to address this question in a review of over 1,000 recent articles published in high‐impact, peer‐reviewed, neuroimaging‐focused journals. Specifically, we sought to ascertain whether, and the extent to which adextrals are underrepresented in neuroimaging study samples, and to delineate potential trends in this bias. Handedness data were available for over 30,000 research subjects; only around 3%–4% of these individuals were adextral—considerably less than the 10% benchmark one would expect if neuroimaging samples were truly representative of the general population. This observation was generally consistent across different areas of research, but was modulated by the demographic characteristics of neuroimaging participants. The epistemological and ethical implications of these findings are discussed.     

Types and Number of Traumas Associated With Suicidal Ideation and Suicide Attempts in PTSD: Findings From a U.S. Nationally Representative Sample

Posttraumatic stress disorder (PTSD) is associated with suicidal ideation and suicide attempt; however, research has largely focused on specific samples and a limited range of traumas. We examined suicidal ideation and suicide attempt relating to 27 traumas within a nationally representative U.S. sample of individuals with PTSD. Data were from the National Epidemiologic Survey of Alcohol and Related Conditions (N = 34,653). Participants were assessed for lifetime PTSD and trauma history, suicidal ideation, and suicide attempt. We calculated the proportion of individuals reporting suicidal ideation or suicide attempt for each trauma and for the number of unique traumas experienced. Most traumas were associated with greater suicidal ideation and suicide attempt in individuals with PTSD compared to individuals with no lifetime trauma or with lifetime trauma but no PTSD. Childhood maltreatment, assaultive violence, and peacekeeping traumas had the highest rates of suicidal ideation (49.1% to 51.9%) and suicide attempt (22.8% to 36.9%). There was substantial variation in rates of suicidal ideation and suicide attempt for war and terrorism‐related traumas. Multiple traumas increased suicidality, such that each additional trauma was associated with an increase of 20.1% in rate of suicidal ideation and 38.9% in rate of suicide attempts. Rates of suicidal ideation and suicide attempts varied markedly by trauma type and number of traumas, and these factors may be important in assessing and managing suicidality in individuals with PTSD.     

Patient expectations of oral implant-retained prostheses in a UK dental hospital

STATEMENT OF PROBLEM: The loss of the natural dentition leads to severe functional impairment in many edentulous adults. A prosthesis retained and supported by osseointegrated dental implants may provide a satisfactory solution for people who have lost all their natural teeth. However, little information is available as to what patients requesting implants expect of implant-retained prostheses. AIM: The aim of this study was to assess the expectations of a group of edentulous patients requesting implant therapy. METHOD: The study included two groups: (1) a group of edentulous adults who requested implant therapy ('implant group'); and (2) an edentulous control group, of similar age and gender distribution as the implant group, receiving conventional complete dentures. Following a clinical and radiographic examination of the patients, data were collected using validated questionnaires. Both groups made a subjective assessment of current dentures. The implant group also completed a questionnaire which assessed expectations of implant-retained prostheses. RESULTS: Baseline satisfaction with current dentures was low in both groups, with the implant group being significantly less satisfied with comfort and stability of their mandibular dentures. Perceived ability of the implant group to chew hard foods was less than the control group. The implant group's expectations of an implant-retained prosthesis were significantly greater than for a conventional denture. CONCLUSION: Careful assessment of patient expectation of implant therapy is essential to determine appropriate treatment need, and to highlight unrealistic expectations.     

In-use peroxide kinetics of 10% hydrogen peroxide whitening strips

OBJECTIVE: Clinical research was conducted to establish the peroxide degradation profile of a very thin 10% hydrogen peroxide bleaching gel delivered on a flexible polyethylene strip. METHODS: Sixteen subjects participated in this study of Crest Whitestrips Premium, a thin layer of 10% hydrogen peroxide gel. Application was supervised, and strips were removed after five, 10, 30, and 60 minutes. Samples were collected from the strips, teeth, gingiva, and saliva, and peroxide levels were derived using a colorimetric peroxide assay. RESULTS: At five minutes, median peroxide concentrations were 7.3%, 6.4%, and 0.7% for strips, teeth, and gingiva, respectively, declining to 4.6%, 2.9%, and 0.1% at 30 minutes. Salivary samples never exceeded a median concentration of 0.014% at any time point. Samples differed significantly (p < 0.01) with respect to the 30- and 60-minute area-under-the-curve calculations, with the highest concentrations on the strip and teeth, and the lowest on the gingiva and in saliva. Median peroxide concentrations on strips and teeth remained above 2% over 60 minutes. At all post-treatment time points, the gingival peroxide concentration was an order of magnitude lower than the teeth samples. CONCLUSION: Use of 10% hydrogen peroxide whitening strips yielded appreciable peroxide on teeth over a 60-minute period, with rapid peroxide degradation on the gingiva, and exceedingly low accumulation in saliva anytime during use.