Assessment of Biomechanical Behavior of Endodontically Treated Premolar Teeth Restored with Novel Endocrown System.

OBJECTIVE: Despite the increased popularity of endocrowns, there is no clear consensus considering their effectiveness to restore severely-destructed endodontically treated premolars. This study aimed to assess the biomechanical behavior of endodontically treated maxillary first premolars restored with a novel endocrown system compared to the conventional one. MATERIALS AND METHODS: Twenty sound human maxillary first premolars were collected. After endodontic treatment, they were divided into 2 groups (n=10) according to the system used for endocrown fabrication. Group C (Control): conventional monolithic IPS e.max CAD endocrowns. Group P: novel bi-layered endocrowns (Pekkton ivory coping veneered with cemented IPS e.max CAD). All specimens were subjected to 10000 thermal cycles followed by 240000 dynamic load cycles. Surviving specimens were subjected to fracture resistance test followed by qualitative analysis using Stereomicroscopy and Scanning Electron Microscopy. RESULTS: A significantly higher load was observed for Group P (1831.37 ± 240.69 N) than Group C (1433.47 ± 174.39 N) (p ⟨ 0.001). A statistically significant difference was observed considering the failure mode (p = 0.036), with more favorable fractures detected with Group P. CONCLUSIONS: The tested novel endocrown system improved the biomechanical behavior of the tooth/ restoration complex in the restored endodontically treated maxillary first premolars. CLINICAL SIGNIFICANCE: The tested novel endocrown system with a PEKK coping veneered with cemented IPS e.max CAD can be considered a promising option for restoration of severely-destructed endodontically treated premolar teeth. It can be considered as a conservative alternative option to the conventional treatment modalities.

Bond Strength Durability of Adhesive Cements to Translucent Zirconia: Effect of Surface Conditioning.

PURPOSE: To evaluate the influence of airborne particle abrasion, Piranha acid and hot acid etching on bond strength of zirconia with self-adhesive resin cements after aging. Also, the effect of Silano-Pen treatment on the bond strength of zirconia to resin cements. MATERIALS AND METHODS: Thirty-six zirconia blocks were cut, sintered and divided into three groups (n=12); Airborne particle abrasion, Piranha acid, and hot acid etching were then treated with Silano-Pen. Each zirconia block was bonded to its corresponding composite block utilizing either Panavia SA, TheraCem or Panavia F2.0. 360 micro -tensile test bars were obtained and half of them were subjected to 10000 thermal aging cycles. Each microtensile test bar was subjected to microtensile force until debonding. Scanning Electron Microscopic evaluation was performed. RESULTS: There was a significant difference between the surface treatments. Hot acid showed the highest mean bond strength and the lowest was Piranha acid. Panavia SA significantly improved the bond strength compared to TheraCem and Panavia F2.0. The interaction between cement and Silano-Pen was non-significant (p=.067). Under SEM analysis, hot acid treatments showed homogenous granular texture with wide distribution of porous network. CONCLUSIONS: Pre-treatment, resin cement, and aging influences the effectiveness of bonding of zirconia. Silano-Pen after hot acid improved the bonding of zirconia.

Cardiac magnetic resonance indices reflecting pulmonary regurgitation burden after tetralogy of Fallot repair.

AIM: To investigate cardiac magnetic resonance (CMR)-derived parameters to determine a convenient index reflecting the degree of pulmonary regurgitation (PR) after Tetralogy of Fallot (TOF) repair. MATERIALS AND METHODS: Sixty-three patients (age at CMR study, 23.6 [10.2-34.7] years, 55.6% male) underwent CMR after TOF repair. PR was quantified using ventricular stroke volume difference and phase-contrast mapping of the main pulmonary artery flow. In both approaches, the PRV index (PRVI) and the PR fraction (PRF) were calculated and correlated to the right ventricle end-diastolic volume index (RVEDVI) and the right ventricle end-systolic volume index (RVESVI). RESULTS: No statistically significant difference was observed between the PR volumes and the PRF measured by the stroke volume difference or the phase-contrast method. The PRVI was better correlated to RVEDVI and RVESVI than the PRF. CONCLUSION: The PRVI exhibits more correlation to the RVEDVI than PRF. Thus, it could be a preferable parameter to reflect the PR burden.

Paravalvular leak after transcatheter aortic valve implantation: is it anatomically predictable or procedurally determined? MDCT study.

AIM: To investigate the determinants of paravalvular leak (PVL) occurring after transcatheter aortic valve implantation (TAVI). MATERIALS AND METHODS: One hundred and eight patients with severe symptomatic aortic stenosis (mean age 75.5±11.8 years, 72.2% male) underwent contrast-enhanced electrocardiogram (ECG)-gated multidetector computed tomography (MDCT) then successful TAVI. The following parameters were determined in the late systolic phase: annular and left ventricular outflow tract (LVOT) diameters, annular perimeter, ellipticity index, annular area, indexed annular area, LVOT perimeter, annulus/LVOT perimeter difference ratio, the LVOT to ascending aorta angle (< LVOT-AO). In the diastolic phase, the extent of calcification of the aortic valve (AVC) was assessed visually and graded semi-quantitatively as grade I, II, and III at the annulus, LVOT, and aortic cusps levels. Pre-discharge transthoracic echocardiography (TTE) was performed, and the PVL was graded as grade I, II, and III. The area-dependent device-annulus sizing ratio was calculated. RESULTS: Absence of PVL was observed in 44.44% of the patients, 30.56% had grade I PVL, 25% of the patients had grade II or above, and any PVL was observed in 55.56%. There was no statistically significant association between the degree of PVL and the extent or the distribution of AVC, aortic annulus diameters, ellipticity index, annulus/LVOT perimeter difference ratio or < LVOT-AO. The frequency of PVL was not significantly different with the use of balloon-expandable or self-expandable valves. A larger transcatheter heart valve (THV)/annulus sizing ratio was associated with a lower incidence and degree of PVL (p<0.001); there was no detectable PVL with a mean sizing ratio of 14.89±7.29, and grade I PVL occurred with a mean sizing ratio 12.43±0.84, while PVL of grade II or above occurred using the mean sizing ratio -0.42±5.57. CONCLUSION: The procedure-related THV/annulus sizing ratio was an important determinant of the degree of PVL after TAVI, whereas the MDCT-derived anatomical measurements of the aortic root and AVC were not predictors of PVL.

Age-hardening reactions in a type III dental gold alloy.

The age-hardening reactions in a commercial type III dental gold alloy were studied by means of hardness test, X-ray diffraction study and scanning and transmission electron microscopic observations. The hardening was attributed to the formation of the metastable AuCu 1' type ordered phase in the grain interior by the isothermal ageing at 225 and 450 degrees C at which two hardness peaks were observed by the isochronal ageing. By ageing at 450 degrees C, the hardening did not begin immediately because the incubation period was required. The age hardening at 225 degrees C was characterized by a slow growth rate of the metastable AuCu 1' type ordered phase. The overageing with softening which occurred following prolonged ageing at 450 degrees C was due to the formation of the lamellar structure composed of the Ag-rich alpha1 and AuCu 1 type ordered phases at grain boundaries.

A coherent phase diagram of the [(AuCu)0.86Ag0.14]1-XPtX pseudobinary section in Au-Cu-Ag-Pt quaternary system.

In order to determine a coherent phase diagram of the [(AuCu)0.86Ag0.14]1-XPtX pseudobinary system, phase identifications and analyses of the microstructural configurations were performed by means of transmission electron microscopy. Various phase regions were detected in the coherent phase diagram as follows; (1) alpha 0 (fcc) single phase region, (2) two-phase region (alpha 1 + alpha 2), (3) AuCu I (L10) + alpha 0, (4) AuCu I + alpha 2, (5) AuCu II (L10-S) + alpha 2, (6) AuCu I + AuCu II + alpha 2, (7) AuCu I single phase region. Microstructural features of these regions relating to the phase transformations were described.

One-year clinical evaluation of two composite materials used for anterior class V restorations.

The purpose of the current study was to evaluate the clinical performance of two composite materials used for filling anterior cavity preparations. A total of 100 class V cavities of anterior tooth were restored with two different composite materials (Palfique Estelite and Palfique Toughwell, 50 cavities each, respectively) in combination with the same bonding agent (Mac Bond II). Colour match, cavosurface marginal discolouration, recurrent caries, wear, marginal integrity and surface texture were evaluated clinically for all restorations on the basis of the United States Public Health Service (USPHS) criteria immediately after insertion (baseline), after 6 months and after 1 year. In the comparison of baseline to 1-year evaluation, the Palfique Toughwell material showed significant changes in all factors except recurrent caries. The Palfique Estelite material, however, showed neither significant cavosurface marginal discolouration nor recurrent caries. No significant difference (P > 0b05) was observed between the two materials in clinical performance after 1 year, with the exception of caries rate, which was found to be significantly lower in the Palfique Estelite material. It was concluded that both composites were clinically reliable materials when used for anterior class V restorations.

Phase transformation behavior in a multipurpose dental casting gold alloy during continuous heating.

Phase transformation in a multipurpose dental casting gold alloy during continuous heating was studied by electrical resistivity measurements, hardness tests, X-ray diffraction and scanning and transmission electron microscopy. The behavior can be explained by the following reaction sequences in the nodule: alpha1(fcc) + alpha2(L1(2)) --> alpha1(fcc) + alpha2(L1(2)) + beta(L1(0)), where fcc is face centred cubic. A discontinuous precipitation with very fine nodules contributed to the hardening and the growth produced the softening. This multipurpose gold alloy is characterized by the introduction of a PtZn ordered phase with L1(0) structure instead of a CuAu I phase.