Mechanical Failure of Endocrowns Manufactured with Different Ceramic Materials: An In Vitro Biomechanical Study

PURPOSE

To evaluate the effect of different silica-based ceramic materials on the mechanical failure behavior of endocrowns used in the restoration of endodontically treated mandibular molar teeth.

MATERIALS AND METHODS

Thirty-six intact mandibular molar teeth extracted because of a loss of periodontal support received root canal treatment. The teeth were prepared with a central cavity to support the endocrowns, replacing the occlusal surface with mesial-lingual-distal walls. Data acquisition of the prepared tooth surfaces was carried out digitally with a powder-free intraoral scanner. Restoration designs were completed on manufactured restorations from three silicate ceramics: alumina-silicate (control), zirconia-reinforced (Zr-R), and polymer-infiltrated (P-I). Following adhesive cementation, endocrowns were subjected to thermal aging, and then, each specimen was obliquely loaded to record the fracture strength and define the mechanical failure. For the failure definition, the fracture type characteristics were identified, and further analytic measurements were made on the fractured tooth and ceramic structure.

RESULTS

Load-to-fracture failure did not differ significantly, and the calculated mean values were 1035.08 N, 1058.33 N, and 1025.00 N for control, Zr-R, and P-I groups, respectively; however, the stiffness of the restoration-tooth complex was significantly higher than that in both test groups. No statistically significant correlation was established in paired comparisons of the failure strength, restorative stiffness, and fractured tooth distance parameters. The failure mode for teeth restored with zirconia-reinforced glass ceramics was identified as non-restorable. The resin interface in the control and P-I groups presented similar adhesive failure behavior.

CONCLUSION

Mechanical failure of endocrown restorations does not significantly differ for silica-based ceramics modified either with zirconia or polymer.

Evaluation of the Serodia Treponema pallidum particle agglutination, the Murex Syphilis ICE and the Enzywell TP tests for serodiagnosis of syphilis

We evaluated the Treponema pallidum haemagglutination assay (TPHA), a treponemal test, with three other treponemal tests, the Serodia T. pallidum particle agglutination assay, the Murex Syphilis ICE IgG + IgM enzyme immunoassay (EIA) and the Enzywell TP IgG + M EIA (a new rapid EIA) for use in conjunction with the rapid plasma reagin test (RPR), a non-treponemal test, for serodiagnosis of syphilis. In all, 124 serum samples were found reactive with RPR and/or TPHA after testing by the routine laboratory protocol. Twenty-three (18.5%) of them were positive only by RPR test and were evaluated as biologically false-positive, 16 were positive only by the TPHA and 84 by both the RPR and TPHA tests; one sample was non-specific (heterophile reaction) in the TPHA.

Agreements of the TPHA with the Serodia TPPA, the Murex Syphilis ICE and the Enzywell TP tests were 96.7%, 100% and 99.1%, respectively.

We conclude that each one of the tests, the Serodia TPPA, the Murex Syphilis ICE and the Enzywell TP, is an appropriate substitute for screening for serodiagnosis of syphilis.

Effects of the inflammatory response on serum omentin levels in early acute and chronic pancreatitis

BACKGROUND AND AIMS

Acute pancreatitis is an acute inflammation of the parenchyma of the pancreas. Several adipokines have been investigated in acute pancreatitis, and these cytokines contribute to inflammation in acute pancreatitis. However, not enough data exist regarding omentin in injuries of the pancreas. Because of a possible common pathogenesis, we aimed to study the association between pancreatic damage and serum omentin levels.

MATERIALS AND METHODS

Twenty-four Sprague Dowley rats weighing 200-250 g were randomly placed into three groups: a sham group (n=8), an acute pancreatitis group (n=8), and a chronic pancreatitis group (n=8). Both rats in the sham group underwent laparotomy, and 0.1 cc of saline solution was injected through the pancreatic canal. On the seventh day, a blood sample was obtained by abdominal aorta puncture, and the pancreas was resected for histological examination. In the acute and chronic pancreatitis groups, 0.1 cc of 4.5% Sodium Taurocholote was injected through the pancreatic canal. Blood samples were obtained and pancreatic resection was performed after 24 hours for the acute pancreatitis group and after 7 days for the chronic pancreatitis group.

RESULTS

Serum omentin levels of rats with chronic pancreatitis (49.37±2.82 ng/ml) were increased compared to both acute pancreatitis (37.79±1.24 ng/ml) (p<0.01) and sham rats (22.49±1.4 ng/ml) (p<0.01). In addition, the omentin level of rats with acute pancreatitis was significantly increased compared to the sham group (p<0.01).

CONCLUSIONS

The elevation in omentin levels in rats in the early stage of pancreatitis was due to the anti-inflammatory effects of omentin; hence, elevated omentin levels improved insulin resistance and caused a significant reduction in glucose levels.

Treatment of iron deficiency anemia induces weight loss and improves metabolic parameters

BACKGROUND

The treatment of iron deficiency anemia is oral iron replacement which has side effects mostly related with gastrointestinal system. A significant rate of the patients that discontinuing the treatment complained of weight gain during treatment in our clinical practise, despite, oral iron preparations are not known to have such a side effect in adults. Therefore, we planned to investigate this myth whether iron preparations cause an increase in weight, waist circumference, body mass index and laboratory metabolic parameters that may accompany to weight gain.

MATERIALS AND METHODS

Twenty-one women admitted to our out-patient clinics with iron deficiency anemia were enrolled to the study. Waist circumference, body weight, body mass index, systolic and diastolic blood pressures, hemogram and other laboratory parameters assessed and recorded at the first visit and repeated 4 to 6 moths after initiation of treatment.

RESULTS

Waist circumference, body weight and BMI significantly reduced in patients after treatment compared to pre-treatment period. Moreover, HDL was increased and triglyceride was decreased significantly in after treatment compared to pre-treatment period.

CONCLUSIONS

We suggest that treatment of iron deficiency may improve not only haematological but also metabolic and anthropometric parameters. Due to the small study population of our cohort, larger prospective studies are needed to confirm our results.

Serum omentin levels predicts mesenteric ischemia

BACKGROUND

Acute mesenteric ischemia (AMI) is an intestinal vascular disease with high mortality. Clinical diagnosis of acute mesenteric ischemia is difficult. Adipose tissue is an important mediator of metabolism and inflammation.Omentin is produced by visceral adipose tissue and decreased serum levels of omentin are associated with poor metabolic outcomes. We aimed to investigate whether serum omentin level predicts early diagnosis of AMI before development of transmural ischemia.

METHODS

Twenty-four Sprague Dawley rats weighted about 200-250 gr grouped in 3 experimental groups as sham, transient ischemia and permanent ischemia. Each group consisted of 8 rats. Blood samples were evaluated to determine serum urea, creatinine, omentin and C-reactive protein (CRP) levels. A blinded histological examination performed with the same histologist for hemotoxileneosine painted ileal tissue samples.

RESULTS

Mean serum omentin level in sham group (27.5±4.67) was significantly elevated compared to rats in Ischemia-reperfusion (IR) group (10.9±9.01).The difference reached the statistical significance (p=0.004). Serum omentin levels were not correlated to urea, creatinine or CRPlevels.

CONCLUSION

Omentin levels may be a biochemical indicator to detect AMI. However, further human studies are needed (Tab. 3, Fig. 3, Ref. 34).

The effect of feto-maternal blood type incompatibility on development of gestational diabetes mellitus

OBJECTIVE

To assess the relation between fetal and maternal blood type (ABO, Rh) incompatibility and development of gestational diabetes mellitus (GDM).

MATERIALS AND METHODS

A total of 500 pregnant women underwent diagnostic test for GDM by a 100-g oral glucose tolerance test (OGTT) after an 8 to 12-h overnight fast participated in this study. OGTT was performed between the 24-28 weeks of gestation, but participants who were at high risk for GDM were tested after the first prenatal visit. In the postpartum period, maternal and infant blood types were determined. Presence of GDM was evaluated in terms of matched and unmatched fetal and maternal ABO and Rh blood types separately.

RESULTS

GDM was detected in 235 participants. Unmatched ABO blood types between the mother-infant pairs were present in 44.7% (n=105) of GDM (+) and 35.8 % (n=95) of GDM (-) patients. Incompatible feto-maternal ABO blood type was positively correlated with development of GDM which was marginally significant. (p=0.045; R=1.2;95% CL; 1.004-1.48). However, Rh feto-maternal blood type incompatibility was not related with development of GDM.

CONCLUSIONS

Feto-maternal ABO blood type incompatibility may be a weak risk factor for the development of GDM.

Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients

This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients (TECs), when zirconia ceramics were coloured at green stage. Zirconia blocks (N=240; 6 mm×7 mm×7 mm) were manufactured from two materials namely, ICE Zirconia (Group 1) and Prettau Zirconia (Group 2). In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid (shade A2). Three different veneering ceramics with different TEC (ICE Ceramic, GC Initial Zr and IPS e.max Ceram) were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys (Esteticor Plus) veneered with ceramic (VM 13) (n=16) acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine (0.5 mm⋅min(-1)). Neither the zirconia core material (P=0.318) nor colouring (P=0.188) significantly affected the results (three-way analysis of variance, Tukey's test). But the results were significantly affected by the veneering ceramic (P=0.000). Control group exhibited significantly higher mean bond strength values (45.7±8) MPa than all other tested groups ((27.1±4.1)-(39.7±4.7) and (27.4±5.6)-(35.9±4.7) MPa with and without colouring, respectively) (P<0.001). While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering <1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered >1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.

Evaluation of patients with nasal polyps about the possible association of desmosomal junctions, RORA and PDE4D gene

OBJECTIVES

Nasal polyposis is chronic inflammatory disease of the nasal mucosa of the nose and sinuses, often associated with chronic non-allergic rhinitis, aspirin intolerance and non-allergic asthma. The etiology of nasal polyposis is unknown. Multiple factors contribute to the development of nasal polyps including genetic predisposition.

PATIENTS AND METHODS

This study was conducted on patients applied due to nasal polyps. Blood samples were collected peripheral vein and stored at 4°C until analysis for DNA extraction. Genomic DNA was extracted from peripheral blood by a standard method, samples were studied in real time PCR. All patients were evaluated about the possible association of DSG1 (rs7236477-G, 96 rxn), DSG3 (rs1941184-C, 96 rxn), PDE4D (rs1588265) and RORA (rs11071559) gene.

RESULTS

32 patients (17 male, 15 female) with nasal polyposis were included to the study. The mean age was 34.9 ± 17.7 years, ranging between 18 and 55 years. Control group was consisted with 50 healthy volunteers without a history of nasal polyp. DSG1, DSG3 and RORA values of the study group were not statistically different from control group (p > 0.05). PDE4D values of the study group were significantly different from control group (p < 0.05).

CONCLUSIONS

Multiple factors contribute to the pathogenesis of nasal polyps including genetic predisposition. The PDE4D family has gained interest in the complex pathogenesis of nasal polyposis. This is likely linked to the mucosal inflammatory response.

Platelet function in euthyroid patients undergoing thyroidectomy in women

BACKGROUND

Several studies have reported several platelet abnormalities in patients with sub-clinical or overt thyroid dysfunctions. The primary mechanism that affects the hemostatic balance is excess or deficiency of thyroid hormones. The different ways of thyroid gland to the platelet function are not yet clearly understood. The relationship between in the thyroid gland and platelet activation without thyroid hormones has not been studied yet.

AIM

The aim of our study is to determine the platelet function in euthyroid patients undergoing thyroidectomy in females.

PATIENTS AND METHODS

The study group includes 52 female euthyroid patients undergoing thyroidectomy. The control group consisted with 21 healthy euthyroid female. Platelet count (PC), platelet mass (PM), mean platelet volume (MPV), and platelet distribution width (PDW) were measured. PM was calculated by multiplying MPV and PLT.

RESULTS

MPV (8.4 ± 1.3 versus 7.9 ± 0.8) and PDW (17.8 ± 1 versus 17.6 ± 0.8) values were similar between the two groups.

CONCLUSIONS

Thyroid gland does not directly affect platelet activation. Accordingly, platelet abnormalities of thyroid disease can be considered to be independent of the underlying thyroid tissue. This finding suggests that association between thyroid diseases and platelet function is dependent on the status of thyroid hormones.

Mean platelet volume in nasal polyps

BACKGROUND

Many studies in literature point out that inflammation related to nasal polyp is mostly dependent on eosinophils and their inflammatory products. Beside eosinophils, platelets may have a role in nasal polyp development. Platelets are involved in haemostasis, tissue repairing and inflammation. However, to our knowledge, there are no reports in the literature that study the association between platelet parameters and nasal polyps.

SUBJECTS AND METHODS

Forty-three patients with nasal polyps and forty-nine healthy controls were enrolled in the study, retrospectively. Laboratory data of patients with nasal polyp were obtained at the time of diagnosis.

RESULTS

There were no statistically significant differences between the two groups in terms of white blood count, haemoglobin, haematocrit and platelet count. The mean platelet volume (MPV) value of the nasal polyp group was significantly lower than the control group (p = 0.025). Mean eosinophil count was significantly elevated in the nasal polyp group compared to the control group (p < 0.001).

CONCLUSIONS

Reduction in MPV may be an indicator for nasal polyp formation. Further studies with a larger study population are needed to detect the possible correlation between eosinophil count and MPV values in patients with nasal polyps.

Effects of different cavity designs on fracture load of fiber-reinforced adhesive fixed dental prostheses in the anterior region

PURPOSE

To evaluate the fracture strength of inlay-retained, surface-retained, and cantilevered fiber-reinforced adhesively fixed dental prostheses (FRA-FDPs) in the anterior region.

MATERIALS AND METHODS

Thirty-two sound human right central incisors and canines were divided into four groups. Test groups were as follows: group 1, both teeth had deep cavity preparation; group 2, both teeth had shallow cavity preparation; group 3, only the canine teeth had deep cavity preparation; group 4, no preparation was made on the abutment teeth. Lateral pontics were restored with FRA-FDPs. All restorations were subjected to fracture loading from the lateral pontic. The restorations were tested in a universal testing machine (LRX Material Testing Machine) with a crosshead speed of 1 mm/min. One-way ANOVA was used for statistical analyses. Fracture modes were examined visually.

RESULTS

The highest (667.3 ± 90.4 N) and the lowest (409.3 ± 158.1 N) debonding values were found for groups 4 and 3, respectively.

CONCLUSIONS

Different preparation designs (inlay-retained, surface-retained) had no significant effect on fracture strength of FRA-FDPs in the anterior region. However, a cantilever design exhibited significantly lower fracture strength. Delamination of the veneering composite was observed as the primary failure type after fracture tests.

Effect of preparation taper and height on strength and retention of zirconia crowns

This study aimed to determine the effect of the taper and height of tooth preparations on the fracture strength and retention of zirconia crowns. Sixty-four dies were designed to simulate a crown preparation. Dies were machined with a height of either 4 mm (n = 16) or 7 mm (n = 16) and a taper of either 6 degrees (n = 16) or 20 degrees (n = 16). Copings were created from Lava zirconia blanks. Retention tests were performed using a universal testing machine. Copings were recemented on the dies, thermocycled, and tested for fracture strength. Data were analyzed using factorial analysis of variance. Retention was greater in the taller and less-tapered preparation designs. Taller preparations showed superior fracture strength. Preparing posterior teeth with higher axial walls and less taper is recommended to achieve increased retention and strength for zirconia crowns.