Comparison of Fracture Resistance between Implant-supported Bis-acryl Interim 3-unit FDPs Using Six Different Strengthening Mechanisms: An In Vitro Study

AIM

To investigate six different strengthening mechanisms for three-unit implant-supported provisional restorations.

MATERIALS AND METHODS

Six techniques of provisional fixed prostheses (PFP) reinforcement were investigated and were assigned to different groups (n = 10): group (ZP) zirconia powder, group (SK8) silk thread wrapped as a figure-of-8 pattern around middle third of abutment, group (RC8) size 00 retraction cord wrapped as a figure-of-8 pattern around middle third of abutment, group (RF8) Resin impregnated glass fiber ribbon wrapped as a figure-of-8 pattern around abutment, group (KV8) Kevlar 29 cord wrapped as a figure-of-8 pattern around middle third of abutment, group (KV) Kevlar 29 strands incorporated in resin mix. Compared against unenforced bis-acryl as control group (CL). Seventy Metal Dies were 3D printed having Soft Tissue Gingiva Mask. Using a custom-made silicone Index, 70 PFP were fabricated (10 of each group) and were cemented to their corresponding metal dies using zinc polycarboxylate cement. All specimens were thermal cycled for 1000 cycles using order of 20 seconds at 55°C and 20 seconds at 5°C with 10 seconds transport. Fracture resistance test was done using universal testing machine. All specimens were loaded to failure. Data were collected, tabulated and statistically analyzed.

RESULTS

Kolmogorov-Smirnov normality test showed no significant difference between data in each group. So, data are normally distributed in each group. Descriptive statistics showed higher mean values of CL group (780.8 ± 164) followed by RF8 group (614.2 ± 158.2), followed by RC8 group (550.2 ± 339.2), followed by KV8 group (442.1 ± 198.4), followed by KV group (403.9 ± 306), followed by SK8 group (175.9 ± 90.8), and finally ZP group (136.5 ± 135.7). One-way ANOVA revealed significant difference between the tested groups (p = 0.036).

CONCLUSION

Bis-acryl provisional restorations had better mean fracture resistance values than all other strengthening mechanisms. Bis-acryl provisional restorations did not gain more strength by any of the added materials. One-way ANOVA revealed significant difference between all tested groups.

CLINICAL SIGNIFICANCE

Provisional restorations over implant should be strong enough to serve for the long period of bone and tissue healing. Current materials alone cannot survive for long. It serves as temporization between steps of fixed restorations construction. How to cite this article: Rayyan M, Sayed M, Hujeiry AM et al. Comparison of Fracture Resistance between Implant-supported Bis-acryl Interim 3-unit FDPs Using Six Different Strengthening Mechanisms: An In Vitro Study. J Contemp Dent Pract 2023;24(11):840-846.

Informal creditors and sovereign debt restructuring

A conventional view of sovereign debt restructuring suggests that costly sovereign debt restructuring is required to lower the interest rate charged on it. In the presence of a negative external shock, under certain conditions, we show that (a) debt restructuring leads to interim social welfare gains and ex ante efficiency gains, (b) participation by citizens will lead to efficient debt restructuring. Using our results, we discuss provide a normative case for the proposed UNCTAD Roadmap.

Video-based screening for children with suspected autism spectrum disorder - experience during the COVID-19 pandemic in India

BACKGROUND

Assessments for children with autism spectrum disorder (ASD) must adapt to the current COVID-19 pandemic through innovation in screening and assessment strategies using technology. To our knowledge there are no such studies reported from India. We aimed to study the predictive ability of video-based screening tool with definitive diagnosis in children with ASD.

METHOD

Thirty-nine children were screened independently by two examiners with a video-based screening tool to start intervention followed by an in-person evaluation by clinical DSM-5 diagnosis three months later.

RESULT

Similar to studies from developed countries, videos assessments showed a 94.87% correlation with the final diagnosis. Interobserver video agreement had a kappa correlation of 0.803, which was classified as substantial agreement.

CONCLUSION

Video-based evaluations may be used as an interim assessment to initiate early intervention in children with ASD in resource-limited setups in the current pandemic situation. Large, well-designed prospective studies are required to confirm our results.

Responsibility with a Safety Net: Exploring the Medical Student to Junior Doctor Transition During COVID-19

INTRODUCTION

The Foundation Interim Year-one (FiY1) Programme was part of a UK strategy to increase the medical workforce in response to the COVID-19 pandemic. However, the strategy was introduced urgently without evidence. We sought to explore the transition experience of medical student to FiY1 to foundation doctor, with a view to inform future undergraduate education.

METHODS

In this hermeneutic phenomenology study, semi-structured individual interviews were completed with nine foundation doctors who had experience of an FiY1 placement. A template analysis approach was taken, and themes reported.

RESULTS

Participants reported that FiY1 tended to offer a positive experience of transition as a stepping stone to becoming a foundation doctor. Having a degree of clinical responsibility including the right to prescribe medication with supervision was highly valued, as was feeling a core member of the healthcare team. Participants perceived that FiY1 made them more prepared for the foundation transition, and more resilient to the challenges they faced during their first foundation job.

DISCUSSION

The FiY1 fostered many opportunities for junior doctors to bridge the transition to foundation doctor. Aspects of the FiY1 programme, such as early licencing and increased team membership, should be considered for final-year students in the future.

Metabolic Parameters as Predictors for Progression Free and Overall Survival of Patients with Metastatic Colorectal Cancer

We tested the prognostic relevance of metabolic parameters and their relative changes in patients with metastatic colorectal cancer (mCRC) treated with monoclonal antibody and chemotherapy. SUVmax (standardized uptake volume), SAM (standardized added metabolic activity) and TLG (total lesion glycolysis) are assessed with 18F-fluorodeoxyglucosepositron emission tomography and computed tomography (FDG-PET/CT) to evaluate total metabolic activity of malignant processes. Our purpose was to investigate the change of glucose metabolism in relation to PFS (progression free survival) and OS (overall survival). Fifty-three patients with mCRC with at least one measurable liver metastasis were included in this prospective, multi-center, early exploratory study. All patients were treated with first-line chemotherapy and targeted therapy. Metabolic parameters, like SUVmax, SAM, normalized SAM (NSAM) and TLG were assessed by FDG-PET/CT, carried out at baseline (scan-1) and after two therapeutic cycle (scan-2). Our results suggested neither SUVmax nor TLG have such prognostic value as NSAM in liver metastases of colorectal cancer. The parameters after the two cycles of chemotherapy proved to be better predictors of the clinical outcome. NSAM after two cycles of treatment has a statistically significant predictive value on OS, while SAM was predictive to the PFS. The follow up normalized SAM after 2 cycles of first line oncotherapy was demonstrated to be useful as prognostic biomarkers for OS in metastatic colorectal cancer. We should introduce this measurement in metastatic colorectal cancer if there is at least one metastasis in the liver.

Evaluation of the Flexural Strength of Interim Restorative Materials in Fixed Prosthodontics

STATEMENT OF THE PROBLEM

Mechanical properties of interim restorations are considered as important factors specially when selecting materials for long-term application or for patients with para-functional habits. Flexural strength is one of the most important components of these restorations.

PURPOSE

The purpose of this study was to compare the flexural strength of five interim restorative materials.

MATERIALS AND METHOD

Fifty identical samples sized 25×2×2-mm were made from five interim materials (TempSpan; Protemp 4, Unifast III, Trim, and Revotek LC) according to ADA specification #27. The specimens were stored in artificial saliva for 2 weeks and then thermocycled for 2500 cycles (5-55˚C). A standard three-point bending test was conducted on the specimens with a universal testing machine at a crosshead speed of 0.75mm/min. Data were analyzed by using one-way ANOVA and Tamhane's post-hoc tests to measure the flexural strength of temporary materials.

RESULTS

One of the bis-acryl resins (TempSpan) showed the highest, and the light polymerized resin (Revotek LC) showed the lowest flexural strength. The mean values of flexural strength (MPa) for the examined materials were as follow: TempSpan=120.00, Protemp 4=113.00, Unifast III=64.20, Trim= 63.73 and Revotek LC=47.16. There were significant differences between all materials except Trim and Unifast III which did not show any statistical significant difference.

CONCLUSION

Bis-acryl resins were statistically superior to traditional methacrylate and light-cured resins. Therefore, application of bis-acryl resins should be deliberated in patients with heavy occlusion and in cases that need long-term use of interim restorations.

Proportion of false-positive lesions at interim and end-of-treatment FDG-PET in lymphoma as determined by histology: Systematic review and meta-analysis

PURPOSE

To systematically review and meta-analyze the proportion of false-positive lesions at interim and end-of-treatment ¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in lymphoma using biopsy as reference standard.

MATERIALS AND METHODS

Medline was searched for original studies. Methodological quality of included studies was evaluated, and results were meta-analytically summarized using random effects (in case of interstudy heterogeneity [I²≤50%]) or fixed effects (in case of no interstudy heterogeneity [I²>50%]).

RESULTS

Eleven studies, comprising 139 patients who underwent biopsy of an FDG-avid lesion during or after completion of antilymphoma treatment, were included. Overall methodological quality was moderate. The proportion of false-positive results among all biopsied FDG-avid lesions at PET performed during of after completion of treatment ranged between 7.7% and 90.5% (the vast majority was due to inflammatory changes), with a weighted summary proportion (random effects, I²=75.7%) of 55.7% (95% confidence interval [CI]: 32.6-76.6%). There were no available studies on interim FDG-PET in Hodgkin lymphoma. The pooled summary false-positive proportions were 83.0% (95% CI: 72.0%-90.2%) for interim FDG-PET in non-Hodgkin lymphoma (fixed effects, I²=27.7%), 23.1% (95% CI: 4.7%-64.5%) for end-of-treatment FDG-PET in Hodgkin lymphoma (random effects; I²=67.1%), and 31.5% (95% CI: 3.9%-83.9%) for end-of-treatment FDG-PET in non-Hodgkin lymphoma (random effects, I²=68.3%).

CONCLUSION

Both interim and end-of-treatment FDG-PET scans in patients with lymphoma suffer from a very high number of false-positive FDG-avid lesions. This finding, in combination with the previously reported high number of false-negative FGD-PET scans for residual disease detection, suggests that the role of interim and end-of-treatment FDG-PET should be reconsidered.

Prognostic value of interim FDG-PET in R-CHOP-treated diffuse large B-cell lymphoma: Systematic review and meta-analysis

This study aimed to systematically review and meta-analyze the prognostic value of interim (18)F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). MEDLINE and EMBASE were systematically searched for suitable studies. Included studies were methodologically appraised, and results were summarized both descriptively and meta-analytically. Nine studies, comprising a total of 996 R-CHOP-treated DLBCL patients, were included. Overall, studies were of moderate methodological quality. The area under the summary receiver operating curve (AUC) of interim FDG-PET in predicting treatment failure and death were 0.651 and 0.817, respectively. There was no heterogeneity in diagnostic odds ratios across available studies (I(2)=0.0%). At multivariable analysis, 2 studies reported interim FDG-PET to have independent prognostic value in addition to the International Prognostic Index (IPI) in predicting treatment failure, whereas 3 studies reported that this was not the case. One study reported interim FDG-PET to have independent prognostic value in addition to the IPI in predicting death, whereas 2 studies reported that this was not the case. In conclusion, interim FDG-PET in R-CHOP-treated DLBCL has some correlation with outcome, but its prognostic value is homogeneously suboptimal across studies and it has not consistently proven to surpass the prognostic potential of the IPI. Moreover, there is a lack of studies that compared interim FDG-PET to the recently developed and superior National Comprehensive Cancer Network-IPI. Therefore, at present there is no scientific base to support the clinical use of interim FDG-PET in R-CHOP-treated DLBCL.

Prognostic value of interim and end-of-treatment FDG-PET in follicular lymphoma: a systematic review

This study aimed to systematically review the prognostic value of interim and end-of-treatment ¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in follicular lymphoma during and after first-line therapy. The PubMed/MEDLINE database was searched for relevant original studies. Included studies were methodologically assessed, and their results were extracted and descriptively analyzed. Three studies on the prognostic value of interim FDG-PET and eight studies on the prognostic value of end-of-treatment FDG-PET were included. Overall, studies were of poor methodological quality. In addition, there was incomplete reporting of progression-free survival (PFS) and overall survival (OS) data by several studies, and none of the studies incorporated the Follicular Lymphoma International Prognostic Index (FLIPI) in the OS analyses. Two studies reported no significant difference in PFS between interim FDG-PET positive and negative patients, whereas one study reported a significant difference in PFS between the two groups. Two studies reported no significant difference in OS between interim FDG-PET positive and negative patients. Five studies reported end-of-treatment FDG-PET positive patients to have a significantly worse PFS than end-of-treatment FDG-PET negative patients, and one study reported a non-significant trend towards a worse PFS for end-of-treatment FDG-PET positive patients. Three studies reported end-of-treatment FDG-PET positive patients to have a significantly worse OS than end-of-treatment FDG-PET negative patients. In conclusion, the available evidence does not support the use of interim FDG-PET in follicular lymphoma. Although published studies suggest end-of-treatment FDG-PET to be predictive of PFS and OS, they suffer from numerous biases and failure to correct OS prediction for the FLIPI.