Effect of Framework's Manufacturing Technique on Screw's Preload of Implant Supported Prosthesis

Background

Implant supported prosthesis is a common treatment modality. Nowadays, new manufacturing techniques are available to fabricate them.

Aims

To evaluate the effect of different manufacturing techniques of implant supported frameworks (ISF) on the preload of abutment's screws.

Materials and Methods

A mandibular edentulous acrylic model with four dental implants temporarily stabilized in the interforaminal area was used. One ISF was fabricated using the conventional technique; implants were removed from the model and reassembled into the framework; this framework served as the passively fitting framework (PF). Three additional frameworks were constructed: conventional cast framework (CF), milled framework (MF) and 3D-printed framework (3D-PF). The gap between the frameworks and the neck of the implants were recorded in microns using a digital microscope. A tightening torque (TT) of 35 N·cm was applied to all the four abutments' screws and the screw's preload was recorded using two methods, by strain gauges (SGs) that were attached to the neck of each implant and fed into a stain book in microstrain (μɛ) and by removal torque (RT) using a digital torque meter.

Results

The frameworks' gap means from the lowest to the highest were PF, CF, 3D-PF, and MF. The RT was significantly lower than the TT in all frameworks (P ≤ 0.05). One-way analysis of variance (ANOVA) revealed that the PF had the lowest RT, while the CF and the 3DPF both had the highest RT, and those differences were found to be statistically significantly (P ≤ 0.05). When preload of the frameworks was recorded by SGs, one-way ANOVA revealed that PF had the highest preload value, while both 3D-PF and MF had the lowest preload values, those differences were also found to be statistically significant (P ≤ 0.05).

Conclusion

The fabrication of implant-supported frameworks using milling or selective laser melting computer aided design/computer-aided manufacturing technologies did not necessarily enhance the screw's preload. This lack of enhancement could be attributed to the great amount of marginal gap in the frameworks fabricated by both techniques.

Upfront Alternative Donor Transplant versus Immunosuppressive Therapy in Patients with Severe Aplastic Anemia Who Lack a Fully HLA-Matched Related Donor: Systematic Review and Meta-Analysis of Retrospective Studies, on Behalf of the Severe Aplastic Anemia Working Party of the European Group for Blood and Marrow Transplantation

Idiopathic aplastic anemia is a rare and life-threatening disorder, and hematopoietic stem cell transplantation (HSCT) from a matched sibling donor (MSD) is the standard treatment strategy for young patients. Alternative donor transplantation (ADT) from a matched unrelated donor or an HLA haploidentical donor is not commonly used in the frontline setting. This systematic review/meta-analysis was conducted to compare ADT as an upfront, rather than delayed, treatment strategy in the absence of an MSD to immunosuppressive therapy (IST) in severe aplastic anemia (SAA). We searched PubMed/MEDLINE and Embase (1998 to 2019) for studies that compared the outcomes of ADT with IST as upfront therapy in patients with SAA. We included studies with 5 patients or more in each arm. Studies that included patients with inherited forms of bone marrow failure syndromes were excluded. The primary outcome was the 5-year overall survival (OS) rate. Five studies met the inclusion criteria and were included in this meta-analysis. The pooled 5-year odds ratio (OR) for OS was statistically significant at 0.44 (95% confidence interval [CI], 0.23 to 0.85) in favor of upfront ADT. In addition, survival was compared between upfront ADT versus salvage ADT in 6 studies. The pooled 5-year OR for OS was statistically significant at 0.31 (95% CI, 0.15 to 0.64) in favor of upfront ADT. Although this analysis has some limitations, including the retrospective nature of the included studies, the lack of ethnic diversity, the predominantly pediatric population, and the relatively suboptimal IST regimen used in some of the studies, it indicates that upfront ADT is a potential alternative treatment option in young and pediatric SAA patients who lack an HLA identical sibling donor, particularly when optimal IST is not available. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Effectiveness of intravenous high-dose methotrexate for prevention of relapse in patients with DLBCL

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Background: Central nervous system (CNS) relapse develops in 2-10% of patients with diffuse large B cell lymphoma (DLBCL) and has an adverse prognosis. Tools like IPI and CNS-IPI scores identify patients at high risk of systemic or CNS relapse based on the presence of established risk factors ( Schmitz et al. JCO 2016). International guidelines propose prophylactic intravenous high-dose methotrexate (HD-MTX) for patients at high risk of CNS relapse; however, limited data is backing this approach. Methods: We conducted a retrospective review of newly diagnosed DLBCL patients aged 18-75 years treated with curative intent at large academic medical centers in Riyadh, Saudi Arabia, between 2015-2018. Patients who were planned for CNS HD-MTX after cycles 2, 4, and 6 of R-CHOP and received at least one HD-MTX cycle were included. Results: We identified 35 DLBCL patients who received at least one R-CHOP cycle with one cycle of HD-MTX. The median IPI and CNS-IPI score were 3, (range = 0-4) and 3, (range = 0-5), respectively. The median number of R-CHOP cycles received was 6 (range 3-6) and HD-MTX 3 (range 1-6). The overall response rate was 91%, with 3 (9%) primary refractory patients per interim evaluation on cycle 3 of R-CHOP. Achieving complete remission after six cycles of RCHOP was noted in 80%, with four additional patients showed residual disease at the end of treatment evaluation. The entire cohort's overall survival was not reached, and five years estimated survival is 75%. With a median follow-up duration of 37.3 months, none of the patients relapsed after achieving CR at the end of treatment evaluation. The risk of systemic or CNS relapse in our cohort was 0%. In restricting the analysis to CNS-IPI of ≥ 4, a total of 13 patients with a median follow-up of 42 months were included; four patients did not achieve CR by the end of treatment, while nine patients continue to be in CR without any evidence of relapsed disease. Conclusions: High-dose methotrexate with high-intensity chemoimmunotherapy (R-CHOP) seems to be associated with an improvement in the expected rate of CNS relapse. Our data set is small, and a more extensive study evaluating HD-MTX's effectiveness in high-risk DLBCL is warranted.[Table: see text]

Case Report: Klippel-Trenaunay Syndrome - Recurrent Venous Thromboembolism and Vascular Malformation

Klippel-Trenaunay Syndrome (KTS) is a rare genetic vascular disorder characterized by a limb affected by varicose veins, port wine stains, and hypertrophy of bone and soft tissue. It can also present with vascular malformations in the gastrointestinal tract, liver, spleen, genitourinary tract, and heart. We present a 27-year-old case of KTS diagnosed in adulthood associated with recurrent venous thromboembolism and gastrointestinal bleeding.