In Vitro Evaluation of marginal adaptation of polyether ether ketone and zirconia copings

Background

Polyether ether ketone (PEEK) has emerged as a new thermoplastic material with potential applications as a restorative material. Aim: This study aimed to evaluate the marginal adaptation of PEEK copings compared to zirconia copings using field emission scanning electron microscopy.

Materials and Methods

A freshly extracted maxillary central incisor was prepared for a full-coverage restoration following standard principles of tooth preparation. The tooth was sent to a laboratory for fabrication of samples using computer-aided design and manufacturing (CAD/CAM). Twenty samples of polyether ether ketone (PEEK) copings (group A) and 20 of zirconia copings were fabricated (group B). The copings were scanned under a field emission scanning electron microscope and measurements were taken at four distinct points. The marginal adaptation over the buccal, lingual, mesial, and distal margins for both groups was evaluated. One-way analysis of variance (ANOVA) and independent t test were applied.

Results

Our findings indicate that PEEK showed better marginal adaptation than zirconia at all measurement points. The mean marginal gap value of the PEEK group was 33.99 ± 8.81 μm and of the zirconia group was 56.21 ± 15.07 μm. On comparing marginal adaptation among the mesial, distal, buccal, and lingual aspects, PEEK showed better adaptation on all four margins, with the best adaptation on the buccal margin that had the lowest mean gap value of 29.27 ± 6.07 μm. The zirconia group adapted best at the distal margin, with a lowest mean gap value of 53.58 ± 15.25 μm (P ≤ 0.05).

Conclusion

PEEK copings had better marginal adaptation and fit compared to zirconia copings. It may have applications as a restorative material in fixed prostheses.

Technical and clinical assessment of latest technology SiPM integrated digital PETCT scanner

OBJECTIVE

The aim of this study was to conduct a technical and clinical evaluation of a Silicon Photomultiplier (SiPM) integrated digital Positron Emission Tomography - Computed Tomography (PETCT) Scanner using National Electrical Manufacturers Association (NEMA) NU 2- 2018 standards.

METHODS

System sensitivity was measured by using a NEMA sensitivity phantom. Scatter fraction, count-rate performance, accuracy of count loss, and timing resolution were all computed. Clinical images were acquired and image quality was assessed and compared with published studies.

RESULTS

At 1 cm, tangential, radial, and axial spatial resolutions were 3.02 mm, 3.02 mm, and 2.73 mm at full width half maximum (FWHM), respectively. Sensitivity at centre and 10 cm was 10.359 cps/kBq and 9.741 cps/kBq, respectively. The timing resolution was measured at 372 ps.

CONCLUSION

The digital PETCT exhibits a high-spatial resolution and a superior timing resolution, which advances the diagnostic ability to detect small lesions and boosts the diagnostic confidence.

IMPLICATIONS FOR PRACTICE

Increases clinical relevance by improving the ability to detect and differentiate tiny or low-contrast lesions without compromising radiopharmaceutical dose or overall scan time.

Serrated and non-serrated polyps of the colorectum: their prevalence in an unselected case series and correlation of BRAF mutation analysis with the diagnosis of sessile serrated adenoma

AIMS

To determine the prevalence of colorectal polyps of different types in an unselected population, and to correlate the morphological diagnoses with BRAF mutation analysis.

METHODS

Cases of colorectal polyps diagnosed at endoscopy were retrieved from the files of Southern.IML Pathology. All slides were reviewed and the lesions classified histologically. A diagnosis of sessile serrated adenoma was made even if the characteristic features were present only focally. If there was more than one polyp of a particular type in any patient, one lesion was chosen at random so that the results represent the number of patients with each type of polyp rather than the total number of polyps. A proportion of the polyps was subjected to BRAF mutation analysis.

RESULTS

A total of 1479 patients were identified. Non-serrated ("conventional") adenomas were found in 964 patients (65%), hyperplastic polyps in 437 (30%), sessile serrated adenomas in 57 (3.9%), traditional serrated adenomas in 11 (0.7%) and mixed hyperplastic adenomatous polyps in 10 (0.7%). BRAF V600E mutation analysis was performed in 148 selected cases; mutations were found in 44/49 (90%) of lesions diagnosed as sessile serrated adenoma, in 10/34 (29%) of hyperplastic polyps of microvesicular type, in 4/11 (36%) of traditional serrated adenomas, in 10/10 (100%) of mixed hyperplastic adenomatous polyps, and in 2/42 (5%) of "conventional" adenomas.

CONCLUSIONS

Sessile serrated adenomas are encountered commonly in routine endoscopy practice. The histological diagnosis correlates strongly with the presence of BRAF mutation.

Craniofacial surgery for craniometaphyseal dysplasia

Craniometaphyseal dysplasia (CMD) is a rare congenital bone dysplasia with abnormal bony overgrowth leading to characteristic facial features and cranial nerve compression. We present a 10-year-old child with bony swelling at the nasal root since birth along with decreased hearing in both ears. She had normal developmental milestones and intelligence. On examination, she had bossing of forehead with very broad nasal root, short septum, hypertelorism and epicanthic folds. CT scan with 3D reconstruction revealed grossly thickened calvarium and hyperostosis and sclerosis of the cranial base. As the major concern of the parents was cosmetic, craniofacial reconstruction was performed with good cosmetic outcome.

Vascular and metabolic effects of methacholine in relation to insulin action in muscle

AIMS/HYPOTHESIS

Methacholine (MC) is a nitric oxide vasodilator, but unlike other vasodilators, it potentiates insulin-mediated glucose uptake by muscle. The present study aimed to resolve whether this action was the result of a vascular effect of MC leading to increased muscle perfusion or a direct effect of MC on the myocytes. We hypothesise that vascular-mediated insulin-stimulated glucose uptake responses to MC occur at lower doses than direct myocyte MC-mediated increases in glucose uptake.

METHODS

The vascular and metabolic effects of this vasodilator were examined in rats in vivo using a novel local infusion technique, and in the pump-perfused rat hindlimb under conditions of constant flow.

RESULTS

Local infusion of low-dose MC (0.3 micromol/l) into the epigastric artery of one leg (test) in vivo markedly increased femoral blood flow and decreased vascular resistance, without effects in the contra-lateral leg. Capillary recruitment, but not glucose uptake, was increased in the test leg. All increases caused by MC were confined to the test leg and blocked by local infusion into the test leg of N-nitro-L-arginine methyl ester (L-NAME), but not by infusion of N-nitro-D-arginine methyl ester (D-NAME). In the constant-flow pump-perfused rat hindlimb, infusion of 0.6 micromol/l MC vasodilated the pre-constriction effected by 70 nmol/l noradrenaline or 300 nmol/l serotonin, and this was blocked by 10 micromol/l L-NAME. 2-Deoxyglucose in muscle was increased by 30 micromol/l MC (p<0.05), but was unaffected by 3 micromol/l MC. All increases in 2-deoxyglucose uptake by 30 micromol/l MC were blocked by 10 micromol/l L-NAME.

CONCLUSIONS/INTERPRETATION

MC has dose-dependent effects both on the vasculature and on muscle metabolism. At low dose (0.3-3 micromol/l), MC is a potent vasodilator in muscle, both in vivo and in vitro, without metabolic effects; at higher doses (> or =30 micromol/l) MC has a direct metabolic effect leading to increased glucose uptake. Both the vascular and metabolic effects are sensitive to L-NAME. The low-dose enhancement of insulin action in vivo by MC, which has been reported previously, thus seems to be attributable to vascular effects.

Local methacholine but not bradykinin potentiates insulin-mediated glucose uptake in muscle in vivo by augmenting capillary recruitment

AIMS/HYPOTHESIS

Insulin has nitric-oxide-dependent vasodilatory effects in muscle, including capillary recruitment, that enhance access for itself and glucose. However, nitric-oxide-dependent vasodilators other than methacholine do not enhance insulin action. Our hypothesis is that methacholine, unlike bradykinin, enhances insulin-mediated glucose uptake in muscle by augmenting capillary recruitment.

METHODS

Local infusion of either methacholine or bradykinin into one leg of the anaesthetised rat was made during physiological insulin (3 mU.kg(-1).min(-1)) infusion under euglycaemic conditions and without affecting systemic blood pressure. Whole-body glucose infusion was determined, as was femoral blood flow, 2-deoxyglucose uptake into calf muscles and the metabolism of infused 1-methylxanthine, a measure of capillary recruitment for each leg.

RESULTS

Methacholine alone (0.3 micromol.l(-1)) increased femoral arterial blood flow, increased capillary recruitment but had no effect on 2-deoxyglucose uptake of the test leg relative to the contra-lateral control leg. Insulin alone (systemically) required a glucose infusion rate of 8.7 mg.kg(-1).min(-1) to maintain euglycaemia, increased 2-deoxyglucose uptake and capillary recruitment, but was without effect on femoral blood flow in either leg. Local methacholine with systemic insulin infusion increased femoral blood flow, 2-deoxyglucose uptake and capillary recruitment in the test leg only. Bradykinin (0.07 micromol.l(-1)), alone or with insulin, administered in a manner that increased femoral blood flow similarly to methacholine, did not affect 2-deoxyglucose uptake or capillary recruitment.

CONCLUSIONS/INTERPRETATION

Methacholine but not bradykinin enhances insulin-mediated muscle glucose uptake in vivo. We conclude that methacholine acts at specific sites in the vasculature of muscle to stimulate capillary recruitment and thereby enhance insulin access.

Cushing's disease: pituitary imaging

Fourteen patients with adrenocorticotropic hormone (ACTH)-dependent hypercortisolism underwent pituitary scanning with computed axial tomography (CT) and magnetic resonance imaging (MRI). Computed tomography revealed pituitary macroadenomas in two patients, pituitary hyperplasia in one and a suspicion of pituitary microadenoma in one. Thirteen patients underwent MRI. One with a macroadenoma diagnosed on CT did not undergo MRI. The MRI revealed a pituitary macroadenoma in one, microadenoma in three and hyperplasia in two cases. Magnetic resonance imaging following gadolinium diethylene triamine penta acetic acid (gd-DTPA) enhancement revealed four more pituitary microadenomas. All patients who had pituitary adenomas (micro and macro) and hyperplasia underwent trans-sphenoidal pituitary surgery. One of the two patients, who had an enlarged pituitary on imaging but no demonstrable adenoma, was found to have a microadenoma at surgery. Patients with ACTH-dependent hypercortisolism should undergo MRI of the pituitary gland to identify/localize corticotroph pituitary adenomas. The study should include gd-DTPA enhancement in cases where the scan is normal.

Ruptured supratentorial dermoid cysts

Two cases with ruptured supratentorial dermoid cysts are presented. Computerised tomography and magnetic resonance findings are illustrated. The pathology and differential diagnosis is discussed.

Magnetic resonance imaging of the brain in idiopathic hypogonadotropic hypogonadism

Magnetic resonance imaging (MRI) of the pituitary, hypothalamus and olfactory sulci was performed in 40 patients with idiopathic hypogonadotropic hypogonadism (IHH). Twelve of these patients had an impaired sense of smell (Kallmann's syndrome). Sagittal and coronal imaging revealed no morphological abnormalities in the hypothalamic-pituitary region. On axial imaging rudimentary, hypoplastic or aplastic olfactory sulci were found in eight cases. All patients with olfactory sulcal abnormalities had associated hyposmia (one case) or anosmia (seven cases). Structural defects identifiable on MRI were present only in 20 per cent of patients with IHH.

Undescended testis: evaluation by magnetic resonance imaging

We describe our experience of prospective magnetic resonance imaging (MRI) study in patients of undescended testis, with a 1.5 T equipment using body coil. There were thirty two patients, aged 1.5 to 14 years with a mean age of nine years. Surgical follow up was obtained for thirty one patients. We were able to indicate the position of 26 testes in 22 patients and absence of five testes in three patients. MRI was falsely positive and negative for five and two testes, respectively. Testicular tissue at ectopic site was identified by presence of characteristic signal intensity pattern, mediastinum testis and its location along empty spermatic canal in cases of inguinal testis either singly or in combination. MRI was able to detect atrophic changes in four testes, confirmed on surgery. The study concludes that MR imaging is useful in the localization and tissue characterization of a non palpable testis. However, it is not sensitive enough for complete exclusion of the diagnosis of an undescended testis. Thus a surgical or laproscopic exploration may be needed further in selective cases for the management of patient.

Hepatic arterial infusion of human recombinant tumor necrosis factor-alpha. An experimental study in dogs

Local and systemic toxicities associated with hepatic arterial infusion of human recombinant tumor necrosis factor (rTNF) were studied in healthy adult mongrel dogs. The animals received saline containing human serum albumin with or without rTNF (0.02, 0.2, or 2.0 mg/m2). Arteriograms were made, and blood samples were collected for hematologic and biochemical analyses at regular intervals. The dogs were killed at 1, 3, and 7 days postinfusion and complete necropsies were performed. Specimens were obtained from various tissues for histopathologic evaluation. Results indicated that all but the highest dose of rTNF were well tolerated. Severe histopathologic changes were found in the liver, spleen, and kidneys of the animals receiving 2.0 mg/m2 rTNF. In addition, focal tubular degeneration was found in one dog administered 0.2 mg/m2 rTNF. These data suggest that the upper dose limit for hepatic arterial infusion of rTNF is between 0.2 and 2.0 mg/m2 and that renal function should be closely monitored after infusion.

Magnetic resonance imaging of malignant fibrous histiocytoma

The magnetic resonance imaging (MRI) changes in 39 patients with malignant fibrous histiocytoma (MFH) were reviewed retrospectively. Twenty-one sarcomas were in the lower extremity, five each in the upper extremity and trunk, two each in the neck and heart, and one each in the maxillary sinus, sella turcica, tongue, and spermatic cord. The examinations were performed with spin-echo sequences on a 1.5 Tesla Signa Scanner (GE, Milwaukee WI). Twenty-two tumors exhibited intermediate signal intensity on T1-weighted images and 23 were of high signal intensity on T2-weighted images. There was no significant differences in signal intensity of 12 preoperative and 13 recurrent neoplasms. Twelve of 13 patients were correctly diagnosed as having postoperative changes. The MR sensitivity and specificity for detecting a neoplasm were 96% and 83% respectively, but the signal changes were nonspecific for MFH. When compared to CT in 14 patients, MR better defined the extent of the MFH, its relationship to surrounding tissues and vessels, and best differentiated residual or recurrent disease from postoperative changes when examined at least 3 months after surgery.

Synovial sarcoma: MR imaging

Ten patients with biopsy-proved synovial sarcoma were evaluated by magnetic resonance (MR) imaging on a 1.5-T unit. The lesions showed intermediate signal intensity on T1-weighted images and heterogeneous high signal intensity on T2-weighted images. Tumors were well-demarcated from normal tissues. Additional information included adjacent bone involvement (one case), femoral vein invasion by tumor (one case), and hemorrhage within the tumors (one case). Four patients underwent a repeat MR examination following chemotherapy. This showed a decrease in size and increase in the signal intensity of three tumors on T2-weighted images, proven to be due to necrosis in one. These changes correlated with clinical regression of disease. While MR in synovial sarcoma does not have any specific signal intensity, it proved to be useful in defining the extent of disease and in determining the response to chemotherapy.