Evaluation of metabolic changes in FDG PET/CT imaging after mRNA-based COVID-19 vaccination.

BACKGROUND: It isimportant to evaluate the vaccine-related metabolic changes on FDG PET/CT to avoid confusing results. We here aimed to assess the frequency and intensity of regional and systemic metabolic PET/CT changes of patients who received the mRNAbased COVID-19 vaccine (BNT162b2-Pfizer/BioNTech) and to analyze possible factors affecting these changes. METHODS: Among the patients who underwent FDG PET/CT for any indication in our department between July 2021 and December 2021, 129 volunteer patients with a history of COVID-19 vaccination were included in this prospective observational study. Bilateral axillary lymph nodes, ipsilateral deltoid muscle, bone marrow, spleen, thyroid, and liver FDG uptakes were evaluated visually and semiquantitatively for each examination. RESULTS: The frequencies of positive axillary lymph nodes after vaccination were 40%, 44.4%, 32.6%, and 44.7% in all, 1st dose, 2nd dose, and heterologous vaccination regimens groups, respectively. Maximum standardized uptake values of spleen, liver, and bone marrow were statistically high in patients with positive axillary lymph nodes than with negative ones (p < 0.05). Positive deltoid muscle uptake and diffusely increased thyroid uptake findings were observed in 10 and 8 patients, respectively. The median time interval between vaccination and imaging was 9.5 days for patients with positive axillary lymph nodes and 17 days for patients with negative nodes. In our study group, only 8 patients had a positive documented history of COVID-19 infection. DISCUSSION: Regional and systemic metabolic changes were occasionally found on FDG PET/CT imaging in patients who received the mRNA-based COVID-19 vaccine. To avoid these timely decreasing changes, we recommend managing the ideal timing of imaging or vaccination and taking a careful history.

Pyogenic liver abscess after laparoscopic sleeve gastrectomy.

An infected material in the gastrosplenic area after laparoscopic sleeve gastrectomy (LSG) due to hematoma or staple line leak has the potential to spread of the bacterial content to the liver which can result in pyogenic liver abscess. Presently described is a thirty-seven-year-old female patient with unilocular pyogenic liver abscess two weeks after LSG. The abscess resolved by Ultrasound guided percutaneous drainage plus intravenous antibiotic treatment. Review of the literature regarding 3 other cases with liver abscess after LSG is also presented.

Tuning the properties of metal-organic framework nodes as supports of single-site iridium catalysts: node modification by atomic layer deposition of aluminium.

The metal-organic framework NU-1000, with Zr6-oxo, hydroxo, and aqua nodes, was modified by incorporation of hydroxylated Al(iii) ions by ALD-like chemistry with [Al(CH3)2(iso-propoxide)]2 followed by steam (ALD = atomic layer deposition). Al ions were installed to the extent of approximately 7 per node. Single-site iridium diethylene complexes were anchored to the nodes of the modified and unmodified MOFs by reaction with Ir(C2H4)2(acac) (acac = acetylacetonate) and converted to Ir(CO)2 complexes by treatment with CO. Infrared spectra of these supported complexes show that incorporation of Al weakened the electron donor tendency of the MOF. Correspondingly, the catalytic activity of the initial supported iridium complexes for ethylene hydrogenation increased, as did the selectivity for ethylene dimerization. The results of density functional theory calculations with a simplified model of the nodes incorporating Al(iii) ions are in qualitative agreement with some catalyst performance data.

The Association of Oral Vitamin D and Calcium Supplementation With Bone Mineral Density in Pediatric Acute Lymphoblastic Leukemia Patients.

AIM: To investigate the association of calcium (Ca) and vitamin D (vit D) supplementation with bone mineral density (BMD) in pediatric acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: Group I (n=11): de novo ALL patients aged 1 to 18 years. Group II (n=46): pediatric ALL survivors in first complete remission and ALL patients on maintenance chemotherapy. We stratified group II into 3 subgroups according to the postdiagnosis period (group IIa: 8 to 24 mo, group IIb: 24 to 48 mo, group IIc: >48 mo). Group III (n=22): healthy siblings of group II. Daily oral vit D3 and Ca carbonate was given only to group I. In group I, BMD was measured at diagnosis and after completion of intensive chemotherapy (TP1 and TP2). RESULTS: A significant increase in Ca (P=0.024) and 25-OH vit D (P=0.01), and a decrease in magnesium (P=0.023) were detected at TP2 compared with TP1 in group I. Mean plasma levels of 25-OH vit D were <20 ng/mL in all the groups. Total body (P=0.005), total body less head (P=0.005), and L1 to L4 BMD Z scores (P=0.025) decreased significantly at TP2 compared with TP1. The lowest BMD scores were found at 8 to 24 months after diagnosis in unsupplemented patients. A gradual increase in BMD Z scores was shown, with the highest scores in group IIc. CONCLUSION: Vit D and Ca supplementation in pediatric ALL patients during intensive chemotherapy may not prevent bone mineral loss. BMD scores of pediatric ALL patients described by other studies, as a major decrease in the first 2 years and gradual increase afterward, was also observed in our patients.

Comparison of two procedures for symptomatic hemorrhoidal disease: Ligation under Vision and Ferguson Hemorrhoidectomy - a retrospective cohort study.

OBJECTIVE: To compare Ligation under Vision (LUV) with Ferguson Hemorrhoidectomy (FH) in patients with Grade II, III and IV hemorrhoidal diseases according to their postoperative outcomes. METHODS: Between July 2008 and August 2014, 155 patients underwent FH and 120 patients LUV, in Sakarya University Teaching and Research Hospital. Our retrospective analysis focuses on postoperative complications, postoperative pain and rate of recurrence. In LUV procedure, submucosal tissue of the hemorrhoidal pile base was transfixed using absorbable sutures under direct vision through anoscope in the Jackknife position. RESULTS: In a mean postoperative follow-up period of 51.76+/-22.3 months; ectropion, anal fissure, and anal incontinence were the most frequent complications. The overall complication rate was significantly less after LUV than FH, (6.7% vs. 14.2%, P=0.047). The complication rate and need for a second or third surgery did not significantly differ between the two procedures with the increase in affected quadrants (P>0.05). The visual analog scale (VAS) at 24 hours was similar in both groups (P=0.267). CONCLUSIONS: LUV is a safe, and practical procedure with similar outcomes compared to FH. LUV may be a better choice than excisional hemorrhoidectomies when three or four quadrants of the anal canal are involved with hemorrhoids as this reduces mucosal defect related possible complications such as ectropion and anal stenosis.

Long-term results of endoscopic resection for type I gastric neuroendocrine tumors.

BACKGROUND: A number of different therapies, including endoscopic resection, have been suggested for the treatment of Type 1 gastric neuroendocrine tumors (NETs). The current study aimed to determine the long-term efficacy of endoscopic resection for Type 1 gastric NETs. METHODS: Twenty-two patients (from 1999 to 2012) with Type 1 gastric NETs were included in the study. All patients were treated with endoscopic resection and received regular followed-up appointments at a tertiary referral center. RESULTS: All patients were initially diagnosed with hypergastrinemia, atrophic gastritis and intestinal metaplasia. Polyps' diameters were >1 cm in 4 patients, and between 0.5 and 1 cm in 18 patients. All detectable lesions were successfully resected. One patient required surgery due to gastric perforation during endoscopic mucosal resection. Recurrence was detected in four patients (18%) and endoscopic resection was performed again. Local or distant metastasis was not observed in any patient during follow-up. Median follow-up time was 7 years, with a maximum of 14 years. Seventeen patients (78%) completed a 5-year follow-up period, and overall disease-free survival rate was 100%. CONCLUSIONS: Long-term follow-ups with 22 patients suggest that endoscopic resection of Type 1 gastric NETs is a safe and effective treatment option with a relatively low recurrence rate.

Correlation of Cystatin-C and radionuclidic measurement method of glomerular filtration rate in patients with lung cancer receiving cisplatin treatment.

OBJECTIVE: Cisplatin is a chemotherapeutic agent which affects renal functions adversely. The best indicator of renal functions is glomerular filtration rate (GFR) measurement. Cystatin-C appears to be a good alternative to existing methods of measuring GFR. However, it is controversial whether Cystatin-C demonstrates GFR correctly for patients receiving chemotherapy. This study aimed to investigate the correlation between GFR values calculated by Cystatin-C based formulas, radionuclidic method (multiple blood sampling) and blood Cystatin-C values in patients with lung cancer, receiving cisplatin treatment in both pre-treatment and post-treatment periods. MATERIALS AND METHODS: Thirty-six patients with lung cancer who were going to receive cisplatin treatment were included in this study. However, the evaluation was performed with 20 patients since 16 of them could not complete the treatment. Blood Cystatin-C values, GFR values calculated via Cystatin-C based formulas, and radionuclidic method were investigated before and after the cisplatin treatment. RESULTS: After treatment significant decreases were detected in GFR values, obtained via radionuclidic measuring method. However, there was no significant difference in Cystatin-C values between pre-treatment and post-treatment periods. Also GFR values obtained by Cystatin-C based formulas were not significantly different in pre-treatment and post-treatment periods. There were meaningful correlations between radionuclidic method and Cystatin-C values and Cystatin-C based formulas before treatment. However, all correlations disappeared after the treatment. CONCLUSION: GFR values, calculated by Cystatin-C may not be reliable in following renal functions in patients receiving chemotherapy. When reliable monitoring of the renal functions is necessary radionuclidic method may be preferred in these patients.

Analysis of Ambulatory Proctologic Surgery for Simple Anal Fistulas in Terms of Recovery, Complications, Recurrence, and Cost.

Background Ambulatory anorectal surgeries have increased in the last few years. This clinical study aimed to compare general operating room conditions with outpatient procedures for simple anal fistulas in terms of healing success, recurrence, cost, complications, and sustainability. Methodology Only primary fistulotomy and seton application for simple anal fistulas were retrospectively analyzed. Results Two-hundred fifty patients (73.7%) were male, and 89 (26.3%) were female. Sixty patients (17.7%) were treated in the operating room, and 279 (82.3%) were treated in the outpatient clinic conditions. Of the ambulatory surgeries, 160 patients underwent fistulotomy and 119 patients loose seton. On the other hand, 34 patients underwent fistulotomy and 26 patients loose seton in operating room conditions. No significant difference was found between the groups according to the distribution of age, gender, complications, and recurrence (P > 0.05). Cost-effectiveness assessment according to the place (ambulatory/operating room) and type of operation (fistulotomy/loose seton) reveals that ambulatory surgery provides significantly more savings (P < 0.001). Conclusions For simple anal fistulas, ambulatory anorectal surgery is a safe approach that can be performed at a lower cost than operating room conditions.

Comparison of Bishop's score and cervical length in determining the need for cervical maturation before labor induction.

OBJECTIVES: The aim of this study is to compare the evaluation of cervical length measured by the Bishop score and transvaginal ultrasonography in determining the need for prostaglandin application for cervical ripening in term nulliparous pregnancies. MATERIAL AND METHODS: In our study, a total of 120 patients who were admitted to our hospital between February 2015 and August 2015 were divided into two groups as cervical length group and Bishop score group according to hospitalization order by applying the Permuted Block Randomization method, which is one of the Restricted Randomization methods. Each patient included in the study was evaluated with both the Bishop score and transvaginal ultrasonography. Groups were compared according to the APGAR scores in the 1st and 5th minutes, transition within 12 hours, birthing within 24 hours, birthing with only dinoprostone, birthing with only oxytocin, duration of administration of dinoprostone, duration of oxytocin administration, type of birth, rate of cesarean section, and need for neonatal intensive care. RESULTS: While cervical ripening with dinoprostone was applied to 28 (46.7%) of 60 pregnant women in the Bishop group, labor induction with oxytocin was applied to the remaining 32 (53.3%) pregnant women. In the cervical length group, these values were 33 (55.0%) and 27 (45.0%), respectively. There was no statistically significant difference between study groups in terms of the need for dinoprostone for cervical ripening (p = 0.361). Of those with a Bishop score of 4 or below, 78.6% (n = 22) had a cervical length of over 28 mm, and 71.4% (n = 20) needed oxytocin. Of those with a Bishop score above 4, none of them had a cervical length greater than 28 mm. A statistically significant difference was found between those with a Bishop score of 4 or below and those above 4 in terms of cervical length (p < 0.05). Among those with a Bishop score of 4 or below, the percentage of those with a cervical length above 28 mm was significantly higher than that of those with a Bishop score above 4. CONCLUSIONS: In our study, the delivery time of those with a cervical length of 28 mm and above was significantly higher than those with a cervical length of less than 28 mm, while the bishop score was significantly lower. In order to develop a more objective method that can replace the Bishop scoring system in determining the need for cervical ripening before labor induction, prospective randomized studies that screen larger numbers of patients are needed.

18 F-FDG PET-Positive Large Pelvic Granuloma Mimicking Malignant Bladder Tumor.

ABSTRACT: An 88-year-old man was admitted to our hospital with a recurrent lower urinary tract infection. He had a history of open prostatectomy for benign prostatic hyperplasia 15 years ago and smoking. A mass arising within a bladder diverticula was suspected on the left lateral wall of the bladder on ultrasonography. Although no mass was observed in the bladder lumen on the cystoscopy, abdominal CT detected a left-sided pelvic soft tissue mass. A hypermetabolic mass was detected on 18 F-FDG PET/CT performed because of suspicion of malignancy, and it was excised. Granuloma secondary to chronic vasitis was diagnosed histopathologically.

Evaluation of the location, number and diameter of bezoars in patients with a history of previous gastrointestinal surgery.

OBJECTIVE: Bezoars are foreign bodies developed due to the swallowing of indigestible substances in the stomach that accumulate in the lumen of the gastrointestinal tract. This study aimed to compare the location, size, and diameter of bezoars between patients with and without a history of previous gastrointestinal surgery and between operated and non-operated patients retrospectively. METHODS: A total of 188 patients who presented to our gastroenterology clinic and in whom bezoar was suspected on clinical examination and the diagnosis confirmed through abdominal CT scans were included in the study. The patients were divided into two groups; patients with a history of previous gastrointestinal surgery were assigned to Group 1 (n = 70), and those who had no history of previous surgery (n = 118) to Group 2. RESULTS: The mean age was found as 56.16 ± 15.75 years in Group 1 and 57.71 ± 15.95 years in Group 2. The mean bezoar width was significantly higher in Group 1 (p = 0.049). The mean bezoar length was significantly higher in Group 1 (p = 0.004). Considering localization of bezoars, the rate of patients who underwent enterotomy (80%) was statistically significantly higher than the patients who underwent gastrotomy (23.50%), gastrotomy + milking (28.60%) and milking (44.70%) in the operations performed in the jejunum. CONCLUSION: Bezoars are a rare cause of intestinal obstruction. The median width and length of the bezoars were significantly higher in patients with a history of previous gastric surgery. There was no significant difference in other parameters. The most common localization was jejunum.

Effects of cognitive status on outcomes of groin hernia repair using various anesthesia techniques.

BACKGROUND AND AIM: Because of increasing life expectancy, there is an increasing number of cognitively impaired older individuals undergoing surgeries such as groin hernia repair. Here, we evaluated the effects of cognitive status on postoperative complication rates in patients undergoing groin hernia repair using various anesthesia techniques. We also analyzed the rate of same-day hernia surgery in patients with cognitive decline. METHODS: Patients who presented to our general surgery clinic for unilateral or bilateral inguinal or femoral hernia were prospectively classified into general (group 1), local (group 2), and spinal (group 3) anesthesia groups. The Mini-Mental State Examination (MMSE) was used for preoperative evaluation of each patient's cognitive status. The Visual Analog Scale (VAS) was used to evaluate postoperative pain. Groups were compared in terms of age, MMSE and VAS scores, cognitive decline and complication rates, and surgery duration. RESULTS: In total, 33 (35.1%), 30 (31.9%), and 31 (33.0%) of 94 patients underwent surgery using general, local, and spinal anesthesia, respectively. The mean MMSE score did not differ among groups (p = 0.518). Cognitive decline was present in 18 (19.2%) patients, and the proportion did not significantly differ among groups. The complication rate did not differ between patients with and without cognitive decline. The mean surgery duration was similar among the three groups (p = 0.127). Group 2 had a lower mean postoperative VAS score, compared with the other groups (p < 0.001). Complications because of anesthesia and surgery were significantly more common in group 3 than in the other groups (p = 0.025). In the local anesthesia group, 7 patients had cognitive decline and 22 patients had normal cognition. There were no significant differences between patients with and without cognitive decline in terms of mean surgery duration (50.3 ± 15.4 min vs. 45.2 ± 10.7 min; p = 0.338) or mean VAS score (3.14 ± 0.90 vs. 3.13 ± 0.77; p = 0.985). Among the 22 and 7 patients without and with cognitive decline, 11 (50%) and 0 patients were discharged on the same day (p = 0.025). In the local anesthesia group, the respective median ages were 70, 52, and 59 years for patients with cognitive decline, patients with normal cognition discharged on the same day, and patients with normal cognition who were not discharged on the same day (p = 0.001). CONCLUSION: Groin hernia repair was successfully performed under local anesthesia in all patients, including older patients with cognitive decline. Patients with cognitive decline were not discharged on the day of surgery, although the mean surgery duration and postoperative VAS score did not differ between patients with and without cognitive decline. Prolonged hospitalization in patients with cognitive decline may be related to their advanced age. Further studies are needed to determine the safety of same-day surgery in patients with cognitive decline.

Multi-Level Computational Screening of in Silico Designed MOFs for Efficient SO2 Capture.

SO2 presence in the atmosphere can cause significant harm to the human and environment through acid rain and/or smog formation. Combining the operational advantages of adsorption-based separation and diverse nature of metal-organic frameworks (MOFs), cost-effective separation processes for SO2 emissions can be developed. Herein, a large database of hypothetical MOFs composed of >300,000 materials is screened for SO2/CH4, SO2/CO2, and SO2/N2 separations using a multi-level computational approach. Based on a combination of separation performance metrics (adsorption selectivity, working capacity, and regenerability), the best materials and the most common functional groups in those most promising materials are identified for each separation. The top bare MOFs and their functionalized variants are determined to attain SO2/CH4 selectivities of 62.4-16899.7, SO2 working capacities of 0.3-20.1 mol/kg, and SO2 regenerabilities of 5.8-98.5%. Regarding SO2/CO2 separation, they possess SO2/CO2 selectivities of 13.3-367.2, SO2 working capacities of 0.1-17.7 mol/kg, and SO2 regenerabilities of 1.9-98.2%. For the SO2/N2 separation, their SO2/N2 selectivities, SO2 working capacities, and SO2 regenerabilities span the ranges of 137.9-67,338.9, 0.4-20.6 mol/kg, and 7.0-98.6%, respectively. Besides, using breakdowns of gas separation performances of MOFs into functional groups, separation performance limits of MOFs based on functional groups are identified where bare MOFs (MOFs with multiple functional groups) tend to show the smallest (largest) spreads.

Computational investigation of multifunctional MOFs for adsorption and membrane-based separation of CF4/CH4, CH4/H2, CH4/N2, and N2/H2 mixtures.

The ease of functionalization of metal-organic frameworks (MOFs) can unlock unprecedented opportunities for gas adsorption and separation applications as the functional groups can impart favorable/unfavorable regions/interactions for the desired/undesired adsorbates. In this study, the effects of the presence of multiple functional groups in MOFs on their CF4/CH4, CH4/H2, CH4/N2, and N2/H2 separation performances were computationally investigated combining grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The most promising adsorbents showing the best combinations of selectivity, working capacity, and regenerability were identified for each gas separation. 15, 13, and 16 out of the top 20 MOFs identified for the CH4/H2, CH4/N2, and N2/H2 adsorption-based separation, respectively, were found to have -OCH3 groups as one of the functional groups. The biggest improvements in CF4/CH4, CH4/H2, CH4/N2, and N2/H2 selectivities were found to be induced by the presence of -OCH3-OCH3 groups in MOFs. For CH4/H2 separation, MOFs with two and three functionalized linkers were the best adsorbent candidates while for N2/H2 separation, all the top 20 materials involve two functional groups. Membrane performances of the MOFs were also studied for CH4/H2 and CH4/N2 separation and the results showed that MOFs having -F-NH2 and -F-OCH3 functional groups present the highest separation performances considering both the membrane selectivity and permeability.

PET/CT With 68Ga-PSMA and 18F-FDG in Metastatic Adenoid Cystic Carcinoma: Report of 2 Cases.

ABSTRACT: Adenoid cystic carcinoma (ACC) is a rare and slow-growing tumor, originating from salivary glands. Locoregional recurrence and distant metastasis of ACC can be visualized not only with 18F-FDG but also with 68Ga-PSMA PET/CT due to its high prostate-specific membrane antigen (PSMA) expression. We report 2 cases of metastatic ACC who underwent first 18F-FDG and then 68Ga-PSMA for staging and restaging.

Incidental Uptake of 68Ga-DOTATATE Gastrointestinal Stromal Tumor of Duodenum.

ABSTRACT: A 56-year-old man underwent 68Ga-DOTATATE PET/CT with suspicion of a pancreatic neuroendocrine tumor. However, in this imaging, a mass with 68Ga-DOTATATE uptake was observed not in pancreas but in the duodenojejunal junction. Abdominal tomography confirmed that the heterogeneously enhanced mass was originated from duodenum. The patient was operated, and the histopathology result was evaluated as low-risk gastrointestinal stromal tumor. Although there was low or no specific binding to gastrointestinal stromal tumor cells for all 68Ga-labeled DOTA peptides, uptake of 68Ga-DOTATATE was observed incidentally in this case.

Obesity control and low protein diet preserve or even improve renal functions in Bardet-Biedl syndrome: a report of two cases.

BACKGROUND: Bardet-Biedl syndrome (BBS) is a rare autosomal-recessive disorder characterized by abdominal obesity, mental retardation, dysmorphic extremities, retinal dystrophy, hypogonadism, and kidney structural abnormalities or functional impairment. It is now considered a significant cause of chronic and end-stage renal disease in children. To the best of our knowledge there have been no previous studies on the role of diet in the management of renal functions in patients with BBS. CASE REPORTS: Two siblings, aged 32 and 27 years, with BBS are presented. On admission both patients were obese, with body mass indexes (BMI) of 40 and 39 kg/m2. Their creatinine clearances (CrCl) were 41 and 24 mL/min. After 2 years of follow-up with a diet consisting of 0.6 g/kg/day protein and 1400 kcal/day energy, their BMI's were decreased to 29 and 27 kg/m2, whereas their CrCl's were increased to 44 and 32 mL/min, respectively. 99mTc-MAG3 scintigraphy also revealed improved renal function. CONCLUSIONS: Since this syndrome most likely results in end-stage renal disease, follow-up of renal dysfunction is essential. Low protein diet and/or obesity control may slow the progression of renal failure in patients with BBS.

The bond strength of a highly cross-linked denture tooth to denture base polymers: a comparative study.

PURPOSE: This study compared shear bond strength and type of bond failure between a highly cross-linked tooth and different denture base polymers. MATERIALS AND METHODS: Cross-linked denture teeth were bonded to either a heat-, an auto-, a microwave-polymerized denture base resin or a relatively new injection-molded, microwave-polymerizable polyurethane-based resin. Six experimental groups were established for each of the shear and peel tests. In four of the groups, teeth were used as received and bonded to each of the denture base resins; in the remaining two groups, they were treated with dichloromethane to determine its effect on the bonding with heat or auto-polymerized denture base resins. Bond strength was determined by compressive load applied at 45 degrees on the palatal surface of each tooth until fracture; the type of bond failure was assessed by the peel test. RESULTS: The results showed that heat-cured PMMA groups failed cohesively and demonstrated significantly higher bond strengths than the other resins used. The application of dichloromethane on the ridge lap areas of teeth resulted in a significant improvement of bond strengths in heat- and auto-cured resins. CONCLUSION: Within the limitations of this experimental study, the results suggest that type of denture base material and processing methods may have an influence upon the bond strength between interpenetrating polymer network (IPN) denture teeth and base materials. Treatment of denture teeth with dichloromethane could provide substantial improvement in the bond strength of teeth with heat and auto-cured denture base resins; however, this finding should be validated in further investigations on the long-term effect of such treatment on the bond strength.

Peel bond strength of two silicone soft liners to a heat-cured denture base resin.

PURPOSE: This study investigated the peel strength of two different soft liners to a polymethylmethacrylate (PMMA) denture base resin before and after thermocycling. MATERIALS AND METHODS: The silicone-based soft liner materials tested were Molloplast B and Permaflex; the denture base material was a heat-cured acrylic resin, Meliodent. A total of 40 specimens was prepared using rectangular molds with dimensions of 100 x 10 x 2 mm for PMMA and 150 x 10 x 2 mm for soft liners, as described in ASTM-D903-93. For each of the liner materials, 10 specimens were packed against a cured PMMA denture base surface as recommended by the manufacturers. The other 10 specimens were packed against PMMA denture base dough and processed together. In each group, 5 of the specimens were tested directly, while the other 5 were thermocycled in a water bath (5°C to 55°C; 3000 cycles) before testing. Peel testing was performed using an Instron testing machine. RESULTS: The results revealed that peel strength values of the Permaflex specimens prepared according to the manufacturer's recommendations were significantly higher than those of Molloplast B (p < 0.05). However, when packing was done against uncured PMMA dough, the difference between the specimens of two liners was not significant. Thermocycling led to significant decreases in the peel strength of both Permaflex liner specimens packed against cured/uncured PMMA resin surfaces (p < 0.05), whereas this process did not affect the strength of Molloplast B specimens. CONCLUSION: Results indicated that the material Molloplast B was superior to the material Permaflex in terms of peel strength when the specimens were simultaneously polymerized with PMMA and thermocycled.

Effect of maleic anhydride pretreatment on tensile bond strength of a silicone soft liner to a denture base polymer.

PURPOSE: To determine the effect of resin surface treatment with dissolved maleic anhydride in butanone added into primer on the tensile bond strength between an acrylic denture base resin and a silicone soft liner. MATERIALS AND METHODS: To test tensile bond strength, standard dumbbell-shaped acrylic specimens were prepared. Five experimental groups, including the control, were tested (n = 5). Maleic anhydride solutions prepared in butanone at concentrations of 1%, 5%, 10% or 20% were then mixed with 1 ml of Primo adhesive and the mixtures were applied onto the resin bonding surfaces. Silicone liner material was applied to resin surfaces in the conventional manner. Tensile bond strength of the specimens was measured in a universal testing machine. Fractured surfaces were observed under the scanning electron microscope, and resulting chemical changes with the solutions used were analyzed spectroscopically. RESULTS: The highest bond strength value was obtained for the group treated with 5% maleic anhydride (2.53 ± 0.48 MPa); the lowest value was for the group treated with 20% maleic anhydride (1.59 ± 0.29 MPa). Mixed failure was the dominant type seen in the experimental groups. Spectroscopic analysis showed the interaction of the anhydride carbonyl groups with the Primo primer. CONCLUSION: The treatment of resin surfaces with maleic anhydride added to Primo adhesive effectively increased bond strength between silicone soft liner and denture base resin.