Influence of reinforcing materials on strain of maxillary complete denture

Abstract

Objective. A maxillary complete denture has been a common prosthetic treatment for people with edentulous maxillas. The fracture and deformation of dentures are recurrent and common problems for denture-wearers. Consequently, reinforcement materials are embedded in the denture base to prevent fracture and deformation. The purpose of this study was to examine the influence of reinforcing materials on the strain within the acrylic base of a maxillary complete denture. Materials and methods. Three reinforcements (cast cobalt-chromium bar; glass fibers; and cobalt-chromium wire) were embedded in the bases and a strain-gauge was attached at three positions (labial, middle and posterior) at the mid-line of the polished surface of each denture. A vertical occlusal load of 49 N was applied to the left and right side in the region of the 1st premolar and the 1st molar. Comparisons of the strain were made via ANOVA. Results. The strain of the denture base with a cast cobalt-chromium reinforcement was significantly (p < 0.05) smaller than that with the other reinforcements. Conclusions. This result suggested that a cast cobalt-chromium reinforcement helps to reduce the risk of fracture and deformation of a maxillary complete denture.     

Collaborative behavioral management among parolees: drug use, crime and re-arrest in the Step'n Out randomized trial

Aims To determine whether collaborative behavioral management (CBM) reduces substance use, crime and re‐arrest among drug‐involved parolees. Design Step'n Out was a randomized behavioral trial of CBM versus standard parole (SP) during 2004–08. CBM adapted evidence‐based role induction, behavioral contracting and contingent reinforcement to provide parole officer/treatment counselor dyads with positive tools in addition to sanctions to manage parolees' behavior over 12 weeks. Setting Six parole offices in five states in the USA. Participants Parolee volunteers with a mandate for addiction treatment and a minimum of 3 months of parole (n = 476). Follow‐up was 94% at 3 months and 86% at 9 months. Measurements Drug use and crime in a given month from calendar interviews 3 and 9 months after parole initiation, and re‐arrests from criminal justice administrative data. Findings The CBM group had fewer months in which they used their primary drug [adjusted risk ratio (ARR) 0.20, 95% confidence interval (CI): 0.05, 0.78, P = 0.02] and alcohol (ARR 0.38, 95% CI: 0.22, 0.66, P = 0.006) over follow‐up. CBM had its greatest effects among parolees who reported marijuana or another ‘non‐hard’ drug as their primary drug; parolees who preferred stimulants or opiates did not benefit. No differences were seen in total crime, re‐arrests or parole revocations. Conclusions Collaborative behavioral management may reduce substance use among primary marijuana or other ‘non‐hard’ drug‐using parolees without increasing revocations. Because the majority of drug violation arrests in the United States are for marijuana, these findings have important implications for the management of a substantial proportion of the US community correctional population.     

Abstinence-contingent recovery housing and reinforcement-based treatment following opioid detoxification

Aims To conduct a randomized, controlled trial of abstinence‐contingent recovery housing delivered with or without intensive day treatment among individuals exiting residential opioid detoxification. Design Random assignment to one of three conditions: recovery housing alone (RH), abstinence‐contingent recovery housing with reinforcement‐based treatment RBT (RH + RBT) or usual care (UC). RH and RH + RBT participants received 12 weeks of paid recovery housing contingent upon drug abstinence. RH + RBT participants also received 26 weeks of RBT, initiated concurrently with recovery housing. Assessments were conducted at 1, 3 and 6 months after treatment enrollment. Setting Out‐patient drug‐free substance abuse treatment program in Baltimore, Maryland. Participants Patients (n = 243) who completed medication‐assisted opioid detoxification. Measurements Primary outcome was drug abstinence (opioid‐ and cocaine‐negative urine and no self‐reported opioid or cocaine use in the previous 30 days). Secondary outcomes included abstinence at all time‐points (1, 3 and 6 months), days in recovery housing and employment. Findings Overall rates of drug abstinence were 50% for RH + RBT, 37% for RH and 13% for UC (P < 0.001). At 6 months, RH + RBT participants remained more likely to meet abstinence criteria than UC participants (37% versus 20%, P = 0.016). Length of stay in recovery housing mediated abstinence outcomes and was longer in RH + RBT (49.5 days) than in RH (32.2 days; P < 0.002). Conclusions Abstinence‐contingent recovery housing improves abstinence in opioid‐dependent adults following medication‐assisted detoxification. The addition of intensive ‘reinforcement‐based treatment’ behavioural counseling further improves treatment outcomes, in part by promoting longer recovery house stays.     

Blunted reward responsiveness in remitted depression

Major depressive disorder has been associated with blunted responsiveness to rewards, but inconsistencies exist whether such abnormalities persist after complete remission. To address this issue, across two independent studies, 47 adults with remitted major depressive disorder (rMDD) and 37 healthy controls completed a Probabilistic Reward Task, which used a differential reinforcement schedule of social or monetary feedback to examine reward responsiveness (i.e., ability to modulate behavior as a function of reinforcement history). Relative to controls, adults with rMDD showed blunted reward responsiveness. Importantly, a history of depression predicted reduced reward learning above and beyond residual depressive (including anhedonic) symptoms and perceived stress. Findings indicate that blunted reward responsiveness endures even when adults are in remission and might be a trait-related abnormality in MDD. More research is warranted to investigate if blunted reward responsiveness may predict future depressive episodes and whether targeting reward-related deficits may prevent the re-occurrence of the disorder.     

Avoidance‐based human Pavlovian‐to‐instrumental transfer

The Pavlovian‐to‐instrumental transfer (PIT) paradigm probes the influence of Pavlovian cues over instrumentally learned behavior. The paradigm has been used extensively to probe basic cognitive and motivational processes in studies of animal learning. More recently, PIT and its underlying neural basis have been extended to investigations in humans. These initial neuroimaging studies of PIT have focused on the influence of appetitively conditioned stimuli on instrumental responses maintained by positive reinforcement, and highlight the involvement of the striatum. In the current study, we sought to understand the neural correlates of PIT in an aversive Pavlovian learning situation when instrumental responding was maintained through negative reinforcement. Participants exhibited specific PIT, wherein selective increases in instrumental responding to conditioned stimuli occurred when the stimulus signaled a specific aversive outcome whose omission negatively reinforced the instrumental response. Additionally, a general PIT effect was observed such that when a stimulus was associated with a different aversive outcome than was used to negatively reinforce instrumental behavior, the presence of that stimulus caused a non‐selective increase in overall instrumental responding. Both specific and general PIT behavioral effects correlated with increased activation in corticostriatal circuitry, particularly in the striatum, a region involved in cognitive and motivational processes. These results suggest that avoidance‐based PIT utilizes a similar neural mechanism to that seen with PIT in an appetitive context, which has implications for understanding mechanisms of drug‐seeking behavior during addiction and relapse.     

Efficacy of earphones for 12- to 24-month-old children during visual reinforcement audiometry

Objective: Efficacy of insert and supra-aural earphones during visual reinforcement audiometry (VRA) was investigated for 12- to 24-month-old children. Design: VRA testing began in the soundfield and transitioned to either insert or supra-aural earphones. Audiologists recorded threshold estimates, participant behaviors, and an overall subjective rating of earphone acceptance. Study sample: One hundred and eighty-six 12- to 24-month-old children referred to the Department of Audiology at St. Louis Children’s Hospital for a variety of reasons. Results: Subjective ratings indicated high acceptance of insert earphones (84%) and supra-aural earphones (80%) despite negative behaviors. There was no significant difference in the number of threshold estimates based on earphone type for 12- to 17-month-old participants. Participants in the 18- to 24-month-old age group provided significantly more threshold estimates with insert earphones (mean?=?5.3 threshold estimates, SD?=?3.5) than with supra-aural earphones (mean?=?2.9 threshold estimates, SD?=?2.9). All seven participants who rejected earphone placement were successfully reconditioned for soundfield testing. Conclusions: Data support the use of insert earphones during VRA, especially with 18-to 24-month-old children, to obtain ear-specific information.     

Weaver mutant mice exhibit long-term learning deficits under several measures of instrumental behavior

Homozygous weaver mutant mice (wv/wv) exhibit symptoms that parallel Parkinson's disease, including motor deficits and the destruction of dopaminergic neurons as well as degeneration in the cerebellum and hippocampus. To develop a more complete behavioral profile of these organisms, groups of wv/wv, wv/+ mice and C57BL/6 mice were observed on a within-subjects basis under a fixed-interval schedule of reinforcement, a differential-reinforcement-of-low-rate-of-responding schedule, and a discrimination task in which a saccharin solution and tap water were concurrently available from two food cups. Under both reinforcement schedules, the wv/wv mice responded as frequently as the comparison subjects, but they responded in a manner that was inappropriate to the contingencies. Rather than respond with increasing frequency as the upcoming reinforcer became temporally proximate, wv/wv mice responded with decreasing probability as a function of the time since the previous reinforcer. Under the discrimination task, the wv/wv mice, unlike the controls, obtained saccharin over tap water at the level of chance. The findings suggest that weaver mutant mice express learning deficits similar to those found in other dopamine-deficient organisms.     

The International society for developmental psychobiology 39th annual meeting symposium: Alcohol and development: beyond fetal alcohol syndrome

As has been repeatedly demonstrated, alcohol can exert deleterious morphological and physiological effects during early stages in development. The present review examines nonteratological links existing between alcohol and ontogeny. Human and animal studies are taken into consideration for the analysis of fetal, neonatal, infantile, adolescent, and adult responsiveness to the drug. Sensitivity to alcohol's chemosensory and postabsorptive properties, as well as learning and memory processes mediated by such properties, are examined from this developmental perspective. The studies under discussion indicate that, within each stage in development, we can trace alcohol-related experiences capable of determining or modulating alcohol seeking and intake patterns.     

利用生物材料行腹股沟后壁加强重建技术

利用生物材料行腹股沟后壁加强重建（tARB）技术并非传统意义上的无张力疝修补术,其通过重叠缝合腹横筋膜,加强腹股沟管后壁,尽管增加了一定的张力,但其充分发挥了生物补片的最大优势,即可降解性及组织再生功能。通过tARB技术能够使中青年病人早日恢复正常的工作学习,从而产生比较大的社会效益。此外,tARB技术还能够有效降低病人术后感染和慢性疼痛的风险。鉴于其上述优势,有必要开展多中心的临床研究进一步验证其治疗效果。     

后巩膜加固术在超长眼轴黄斑裂孔性视网膜脱离手术中的应用

目的：评价后巩膜加固术(PSR)辅助超长眼轴黄斑裂孔性视网膜脱离患者玻璃体切除手术(PPV)的临床效果。

方法：采用临床随机对照研究。纳入眼轴≥29mm的超长眼轴黄斑裂孔性视网膜脱离患者46例46眼,随机分为两组：A组采用PSR+PPV+硅油填充,B组采用单纯PPV +硅油填充。随访1a,分析各组术后BCVA、黄斑裂孔愈合情况、视网膜脱离复位率、再手术率等指标。

结果：两组治疗后平均BCVA(LogMAR视力)均较术前改善,A组由1.61±0.02提升为0.85±0.22(t=10.36,P<0.01),B组由1.59±0.04提升为1.08±0.16(t=7.92,P<0.01),其中A组改善幅度大于B组(t=-2.38,P=0.03)。两组术前术后眼轴均无明显改变(P>0.05)。A组一次手术黄斑裂孔愈合率为91%(21/23),取油前再手术率4%(1/23),取油后无再脱离患者,1a随访期内所有术眼完成了硅油取出。B组一次手术黄斑裂孔愈合率为65%(15/23),取油前再手术率35%(8/23),取油后再脱离比例26%(6/23),1a随访期取出硅油比例74%(17/23)。

结论：后巩膜加固术有助于提高病理性近视黄斑裂孔性视网膜脱离的手术成功率,减少复发及再手术的几率。