Surface structure and mechanical properties of impaction-modified Y-TZP

Objectives

The objectives of the study were to describe the surface structure and the chemical surface composition of Y-TZP ceramics produced by using the modified additive technique and to evaluate the flexural strength of Y-TZP with or without surface modification and with different pretreatments: etching before or after sintering combined with or without an adhesive cement system.

Methods

Y-TZP discs were used for surface analysis (n = 48) and for biaxial flexural strength testing (n = 200). The specimens were divided into groups depending on the cementation surface of Y-TZP: unmodified, sandblasted or glass-modified Y-TZP surfaces, and according to the production process: etching before or after sintering.

Results

The surface structure and the chemical composition of glass-modified Y-TZP differ; a rougher surface and phase transformation was identified compared to unmodified Y-TZP.The unmodified Y-TZP groups showed significantly higher flexural strength compared to the glass-modified groups (p < 0.001) and showed increased flexural strength after sandblasting (p < 0.001). Furthermore, by adding cement to the surface, the value increased even further in comparison with the sandblasted non-cemented specimens (p < 0.01). After thermocycling, however, the cement layer on the unmodified and the sandblasted surfaces had air pockets and regions with loose cement.

Significance

A rougher surface structure, superficial glass remnants and a higher content of m-phase was present in the cementation surface of glass-modified Y-TZP. The glass modification creates a bondable cementation surface that is durable. By etching the glass-modified Y-TZP before sintering, a more homogenous surface is created compared to one that is etched after sintering.     

Is there a need for orthodontic plaque indices?—diagnostic accuracy of four plaque indices

Objectives

The aim of this study was to assess the diagnostic performance and accuracy of four plaque indices for orthodontic patients.

Materials and methods

The plaque accumulation of 140 maxillary incisors with bonded brackets was recorded using intra-oral photographs and assessed using four different plaque indices: the orthodontic plaque (OP) index, the modified orthodontic plaque (MOP) index, the Quigley and Hein (QHP) index and the modified Navy plaque (MNP) index. The assessment was performed twice within a time interval of 4 weeks by four different examiner groups: orthodontists, dentists, students and orthodontic assistants.

Results

No significant differences were detected for the OP and MOP indices among the examiner groups. A significant difference was found for the QHP and MNP indices. The inter- and intra-examiner reliability of the OP and MOP indices was good. In contrast, the reliability for the QHP and MNP indices was moderate to poor with few exceptions. The discrimination performance of the OP and MOP indices was excellent. The sum of the sensitivity and specificity was generally lower for the QHP and MNP indices compared with the OP and MOP indices.

Conclusion

OP and MOP indices showed good performance. The QHP and MNP indices are not appropriate for orthodontic purposes.

Clinical relevance

Traditional plaque indices reflect the typical pattern of plaque accumulation for patients without multi-bracket appliances. The performance of these indices for orthodontic patients has never been investigated. Orthodontic plaque indices that focus on the surface along the gingival margin and areas around the bracket exhibit higher diagnostic performance and accuracy compared with traditional indices.     

The outcome after surgical therapy of bisphosphonate-associated osteonecrosis of the jaw—results of a clinical case series with an average follow-up of 20 months

Objectives

The present case series evaluates the success rate of osteotomy and primary wound closure in patients with bisphosphonate-associated osteonecrosis of the jaw (BRONJ).

Materials and methods

Eighty patients suffering from BRONJ were included in the study. All patients received intravenous bisphosphonate therapy and underwent osteotomy and primary wound closure according to a standardised protocol. After discharge, the patients were reviewed on a regular basis over an average time period of 20 months.

Results

During follow-up in 11 patients, a recurrence of BRONJ occurred in the former operation field. Seventeen patients died due to their underlying disease. The success rate of osteotomy and primary wound closure in the treatment of BRONJ was calculated at 84.2 % 20 months after surgery. The results showed non-significant difference concerning the outcome of surgery in the different clinical stages of BRONJ.

Conclusions

In accordance with previous studies, stage-independent osteotomy and primary wound closure combined with antibiotics shall be deemed a viable treatment option in patients suffering from BRONJ.

Clinical relevance

With a high success rate, osteotomy in combination with primary wound closure seems to be a viable alternative to more conservative protocols in the treatment of BRONJ.     

Gut inflammation and expression of ICC in a fetal lamb model of fetoscopic intervention for gastroschisis

Background

The pathogenesis of intestinal dysmotility in gastroschisis is not completely understood. Peel formation and disorganization of interstitial Cajal cells (ICC) have been proposed in humans. The aim of this study was to evaluate the impact of prenatal coverage of gastroschisis on gut inflammation and expression of ICC in a fetal lamb model.

Methods

Twenty-one German blackhead sheep with an abdominal wall defect that was created fetoscopically on day 77 of 145 days gestation were used in this study. Intrauterine surgery with the aim to cover the defect was performed 3 weeks later; two fetuses were covered completely, 5 partially and 11 remained uncovered. Three fetuses without gastroschisis were used as controls. All fetuses were retrieved by cesarean section at day 135. Samples of the small intestine were stained with hematoxylin and eosin for histologic analysis of peel formation and serosal and muscular thickness. For ICC detection, immunohistochemistry using anti-CD117 (c-Kit) antibody was used.

Results

In all samples with exposure to amniotic fluid, peel formation and significantly decreased ICC were found. Complete coverage reduced peel formation and disorganization of ICC compared to uncovered animals almost to the level of controls.

Conclusions

Peel formation and ICC derangement were significantly reduced by prenatal coverage of gastroschisis. Moreover, this animal model mimics the histopathological bowel changes as seen in human gastroschisis and may, therefore, be used for further research on the pathophysiology and fetal therapy of this malformation.     

Use of Short Intertrial Intervals in Single-Trial Experiments: A 3T fMRI-Study

We investigated the detectability of task-related changes in the fMRI-signal in an averaged single trial design under systematic variation of intertrial intervals (ITI) in the range between 4 and 12 s. Investigation of the signal timecourses showed a shortening of the baseline period and subsequently a reduction in signal amplitude with decreasing ITI. The main finding is that effect size, i.e., the ratio of task-related signal changes and error variance remained approximately constant from ITI of 12 s down to 6 s. At ITI = 4 s, the effect size was reduced by about 50%. The effects of ITI reduction were comparable in all six cortical ROI which were analyzed. In two subcortical ROI, effect size was already reduced at longer ITI. At ITI = 4 s, the rising flank of the BOLD response was delayed compared to longer ITI. When the data were corrected for the temporal overlap of successive BOLD-responses, the signal amplitudes at ITI = 4 s were comparable to the amplitudes measured at an interval of 12 s. This indicated that the amplitude reduction was mainly due to a linear superposition of the contiguous BOLD-responses.     

Understanding our context for occupational therapy practice: a key to strategies for future success

The future holds great promise for occupational therapists. Our success in utilizing the opportunities afforded by continuing changes in health care depend on our ability to recognize and act on potential beneficial trends as well as effectively address our challenges. Development of effective partnerships, obtaining required new knowledge and skills, ongoing commitment to evidence-based practice and quality service and demonstrating personal and collective responsibility for advocacy and promotion are key factors for our ability to prosper in these changing times.     

Thoracoscopic posterior tracheopexy for tracheomalacia: A minimally invasive technique

Background

Tracheomalacia is the most common congenital abnormality of the trachea. Posterior tracheopexy to alleviate posterior intrusion contributing to dynamic tracheal collapse has been reported using thoracotomy or median sternotomy. Here we describe the minimally invasive operative technique of thoracoscopic posterior tracheopexy with bronchoscopic guidance.