Evaluation of dimensional accuracy and degree of polymerization of stereolithography photopolymer resin under different postpolymerization conditions: An in vitro study

Statement of problemThe appropriate postpolymerization of stereolithography (SLA) resins with the least effect on dimensional accuracy and with optimal polymerization is unclear.PurposeThe purpose of this in vitro study was to investigate the dimensional accuracy and degree of polymerization of a photopolymer resin for SLA with different postpolymerizing times and temperatures.Material and methodsSixty 1.5-mm-thick specimens were made from clear photopolymer resin with a 3D printer to simulate a maxillary complete denture. They were postpolymerized for different periods (15 and 30 minutes) at 3 different temperatures (40 °C, 60 °C, and 80 °C). Both prepolymerization and postpolymerization gap sizes for each specimen were measured at 5 different locations under a stereomicroscope. The tissue surface was scanned before and after polymerization, and the images were superimposed. The deviation was analyzed by using computer-aided design (CAD) software; root mean square estimates (RMSE) and color map data were obtained. Fourier transform infrared spectrometry was used to determine the degree of conversion (DC) of all specimens. The Kruskal-Wallis and Mann-Whitney tests were used to calculate the difference value of the gap sizes (α=.05). One-way ANOVA and the Tukey test were used for RMSE and DC (α=.05).ResultsThe smallest average change in gap sizes was found at 15 minutes and 40 °C, and the largest change at 30 minutes and 80 °C. The lowest RMSE was obtained at 30 minutes and 40 °C (P<.05). On the color map, a uniform deposited layer was created at 15 minutes and 40 °C and 30 minutes and 40 °C. The highest DC was found at 30 minutes and 60 °C, which differed significantly from 15 minutes and 40 °C (P<.05). The lowest degree of polymerization was found at 30 minutes and 40 °C.ConclusionsThe polymerizing temperature exerted a greater effect than polymerizing time, with lower temperatures leading to improved fit and tissue surface accuracy. The recommended parameters for SLA polymerization are 15 minutes and 40 °C. These conditions offered high dimensional accuracy, favorable surface tissue adaptation, and satisfactory DC.     

Comparison of Torque,Screw-in Force,and Shaping Ability of Glide Path Instruments in Continuous Rotation and Optimum Glide Path Motion

IntroductionThis study aimed to analyze torque/force generation and transportation in double-curved canals instrumented with 3 types of glide path files using optimum glide path (OGP) motion in comparison with continuous rotation.MethodsSixty simulated double-curved canals were prepared with #10/0.05 or #15/0.03 HyFlex EDM Glidepath files (Coltene/Whaledent, Altstätten, Switzerland) or a #13/0.04 prototype MANI Glidepath file (Tochigi, Japan) using OGP motion or continuous rotation (n = 10 each). Canals were sequentially prepared to 20 mm and 22 mm (full working length) using automated root canal instrumentation and a torque/force analyzing device. Transportation was calculated at 1–9 mm from the apex. Data were compared using 2-way analysis of variance followed by a post hoc simple main effect test with Bonferroni correction and a Kruskal-Wallis test (α = 5%).ResultsAll #10/0.05 instruments fractured. In the 22-mm preparation, the OGP motion resulted in lower clockwise torque and screw-in force than did continuous rotation (P < .05). In the 20-mm preparation, #15/0.03 instruments recorded a lower screw-in force for OGP motion than for continuous rotation (P < .05). Comparing the 2 preparation phases, OGP motion generated no significant differences; however, continuous rotation developed higher clockwise torque and screw-in force in the 22-mm preparation than in the 20-mm preparation (P < .05). There was no significant difference among the tested groups for transportation values.ConclusionsCompared with continuous rotation, OGP motion generated less screw-in force, lower clockwise torque, and similar transportation. The #15/0.03 HyFlex EDM instrument and the #13/0.04 prototype MANI instrument performed similarly well.     

Correction to: Swallowing evaluation by the Kuchikara Taberu Balance Chart and videoendscopic examination reveals that respiratory conditions,chewing, and position are strongly related to dysphagia

This study focused on the Kuchikara Taberu Balance Chart (KTBC) as a tool for swallowing function evaluation. To clarify the relationship between videoendoscopic (VE) examination of swallowing function and the KTBC, we compared median KTBC scores with and without laryngeal penetration identified by VE. Sixty-five patients with a mean age of 84.3 ± 7.9 years were examined at the Towada City Hospital. The patients were classified into groups based on laryngeal penetration, including 28 patients with and 37 patients without penetration. We found no significant differences in patient backgrounds. The median KTBC score (interquartile range) was 36.5 (31–44.5) in the group with laryngeal penetration and 42 (35–48.5) in the group without penetration, but the scores were not significantly different (level of statistical significance at α = 0.0036 determined by the Bonferroni correction method) when compared with the Mann–Whitney U test (36.5 vs. 42, z = -2.33, p = 0.020). The median respiratory condition (3 vs. 4, z = − 3.23; p < 0.0036), oral preparatory and propulsive phases (3 vs. 4, z = − 2.96; p < 0.0036), and position and endurance (1 vs. 3, z = − 3.25; p < 0.0036) scores were significantly lower in the group with laryngeal penetration. This study revealed a correlation between laryngeal penetration confirmed by VE and KTBC scores. Consequently, respiratory condition, oral preparatory and propulsive phases, and position and endurance may be useful as tools for the assessment of swallowing. In particular, we recommend adding respiratory status to dysphagia screening.

     

Initial report of bridge to recovery in a patient with DuraHeart LVAD

Continuous-flow left ventricular assist devices (LVADs) provide acceptable clinical results, but the long waiting period for heart transplantation leads to diverse complications. LVAD support can cause reverse left ventricular (LV) remodeling that results in the improvement of LV function and allows LVAD removal. We present a case of successful removal of a DuraHeart LVAD because of sufficient recovery of LV function. Before LVAD removal, we conducted an “LVAD weaning test” by decreasing pump speed and performing an additional normal saline infusion test. We consider that the LVAD weaning test can be used in place of the “pulsatile LVAD off test.”     

A case of esophageal cancer with an aberrant right subclavian artery treated with mediastinoscopic esophagectomy

An aberrant right subclavian artery (ARSA) is one of the famous anatomical abnormalities with a prevalence of 0.16–4.4%. In esophagectomy, anatomical abnormalities of the ARSA could cause complications with some surgical procedures. An 85-year old man was referred to our department for esophageal adenocarcinoma that was at a slightly high position for esophagectomy with the abdominal approach. However, he had a significant past medical history. This risk factor made it difficult to perform thoracoscopic esophagectomy. He underwent mediastinoscopic esophagectomy (ME) with the left cervical and laparoscopic approach. The ARSA presented no difficulties with the ME surgical technique including the dissection of the left recurrent laryngeal nerve lymph node. Although this patient had a respiratory dysfunction and some difficulties in a prone position, ME enabled a safe esophagectomy with lymph node dissection.     

Robotic-assisted surgery for rectal cancer with situs inversus totalis: A case report

We present a very rare case of rectal cancer in a patient with situs inversus totalis (SIT), which is a complete transposition of the thoracic and abdominal viscera. A woman in her 60s visited a local hospital reporting bloody stool and was diagnosed with upper rectal cancer and SIT. We made careful preoperative preparations for the congenital anomaly, and robotic-assisted high anterior resection with D3 lymph node dissection was performed. Although we adopted an unusual six-port placement, the operation was performed safely and efficiently without any adverse events. The patient recovered uneventfully. The pathological specimen was classified as pT3N2bM0 with negative resection margins. Robotic-assisted surgery is advantageous for rectal cancer treatment even when anatomical abnormalities make the surgical procedure more difficult.     

Suture Granuloma With False-Positive Findings on FDG-PET/CT Resected via Laparoscopic Surgery

A 61-year-old woman who had undergone total hysterectomy 16 years previously exhibited a pelvic tumor on computed tomography (CT). F-18 fluorodeoxyglucose (FDG) combined positron emission tomography (PET)/CT imaging revealed a solitary small focus of increased FDG activity in the pelvis. A gastrointestinal stromal tumor originating in the small intestine or another type of tumor originating in the mesentery (desmoid, schwannoma, or foreign body granuloma) was suspected; therefore, laparoscopic resection was conducted. A white, hard tumor was found to originate from the mesentery of the sigmoid colon and adhered slightly to the small intestine. The tumor was resected with a negative margin, and the pathologic diagnosis was suture granuloma. The possibility of suture granuloma should be kept in mind in cases of tumors with positive PET findings and a history of surgery close to the lesion. However, it is difficult to preoperatively diagnose pelvic tumors using a biopsy. Therefore, considering the possibility of malignancy, it is necessary to achieve complete resection without exposing the tumor.Key words: Suture granuloma, Laparoscopy, Positron emission tomography (PET)It is very difficult to diagnose suture granulomas preoperatively. F-18 fluorodeoxyglucose (FDG) combined positron emission tomography (PET)/computed tomography (CT) imaging is often used to differentiate benign from malignant tumors that are difficult to diagnose on other modalities, such as ultrasound (US), CT, and magnetic resonance imaging. However, it is not easy to differentiate tumors associated with inflammation or malignancy using FDG-PET/CT. Suture granulomas are known to be benign; however, false-positive findings were observed on PET/CT in our case. In the literature, there are few reports of suture granulomas showing false-positive findings on PET/CT.^1–5 We report here a case in which it was not possible to rule out the potential for malignancy using CT or FDG-PET/CT and the lesion was confirmed to be a suture granuloma based on a pathologic examination following laparoscopic resection.     

Subclinical Hypothyroidism Is Associated With Adverse Prognosis in Heart Failure Patients

Background

It is widely recognized that overt hyper- as well as hypothyroidism are potential causes of heart failure (HF). Additionally it has been recently reported that subclinical hypothyroidism (sub-hypo) is associated with atherosclerosis, development of HF, and cardiovascular death. We aimed to clarify the effect of sub-hypo on prognosis of HF, and underlying hemodynamics and exercise capacity.