Ashleyrosa3807

The aim of this study was to evaluate the effect of different access opening restorative materials on crown retention.

Thirty-eight extracted molars were mounted in resin and prepared for porcelain fused to metal (PFM) crowns. The crowns were fabricated and cemented with zinc phosphate, and the force to displace it was measured with a tensile-testing machine before and after endodontic access preparations. The endodontic access area, crown preparation axial wall, and preparation surface area were measured for comparison. The crowns were then recemented, and access openings were restored with either amalgam or composite before displacement force was remeasured. The restorative material was removed from each access opening; access area was measured and restored again (amalgam with composite or fiber post with composite) for displacement force to be remeasured. Paired t test was used to compare the means of displacement between groups. One-way analysis of variance was used to compare the mean outcome measure within the groups.

Statistical analyses showed retention after unfilled access was significantly lower than intact crowns. Amalgam, composite, amalgam+composite, and fiber post+composite increased retention beyond the original value. There was no statistical difference among the different restorative protocols. Qualitative results indicate that the restorative material remains in the crown after displacement regardless of the material used to restore the access.

The results from this study suggest that an endodontic access cavity decreases retention of a PFM crown. However, subsequent restoration with amalgam, composite, amalgam+composite, or post+composite may increase the original retention of the crown.

The results from this study suggest that an endodontic access cavity decreases retention of a PFM crown. However, subsequent restoration with amalgam, composite, amalgam + composite, or post + composite may increase the original retention of the crown.

The purpose of this study was to investigate the resumption of endodontic practices in Hubei Province, China 1 month after the end of the lockdown.

A Web-based survey was sent to 1069 active endodontic specialists and general dentists who provided endodontic care in Hubei Province from May 7 to May 9, 2020. The survey consisted of 18 questions on demographics, the current situation of endodontic practice for the participants, and concerns regarding contracting or spreading the virus in newly opened endodontic practices.

A total of 322 participants completed the survey. Most respondents (62%) were from Wuhan. Almost 83% of the respondents have resumed their endodontic practice partially or fully. Most respondents in practice (99%) would take measures to screen patients before treatment including paid screening measures. More than 93% of the respondents reported having taken special measures for routine endodontic treatment at this stage, with the most common measure taken being wearing an N95 mask. The rubber dam was recognized as efficient in preventing infection by most respondents. Many respondents were concerned about contracting coronavirus disease 2019 (COVID-19) as a result of routine endodontic practice at this stage, and respondents with more than 11years of endodontic experience were significantly less concerned about infection compared with those with fewer than 5 years of experience (P<.05).

There is a fear of contracting/spreading COVID-19 among endodontic clinicians, the fear is negatively associated with years of practice, and most clinicians believe that rubber dam isolation can protect them and their patients from COVID-19.

There is a fear of contracting/spreading COVID-19 among endodontic clinicians, the fear is negatively associated with years of practice, and most clinicians believe that rubber dam isolation can protect them and their patients from COVID-19.

This study compared the static and dynamic cyclic fatigue resistance of contemporary nickel-titanium instruments with different kinematic, metallurgic, and design features to establish whether the fatigue-reducing effect of the pecking motion differs among different nickel-titanium instruments.

ProTaper Gold (PTG), Hyflex EDM (EDM), Reciproc Blue (RPB), and WaveOne Gold (WOG) files were divided into 2 groups of 10 for the static and dynamic cyclic fatigue resistance tests. A stainless steel artificial canal with 1.5-mm inner diameter, 60° angulation, and 3-mm radius of curvature was used. In the dynamic cyclic fatigue resistance test, speeds were set at 100 and 200mm/min for the descending and ascending motion, respectively. The number of cycles to fracture (NCF) was calculated, the fractured lengths were recorded, and fractographic analysis of the fractured surfaces was carried out by scanning electron microscopy. Data were analyzed statistically with the Kruskal-Wallis test with Bonferroni correction (alpha=0.05).

The RPB and EDM showed significantly higher NCF in the static and dynamic cyclic fatigue resistance tests (P<.05). The dynamic cyclic fatigue resistance test showed significantly higher NCF than the static cyclic fatigue resistance test in the PTG and EDM (P<.05). There was no significant difference between the RPB and WOG (P>.05).

In the experimental condition where the ascending speed was higher than the descending speed, the dynamic cyclic fatigue resistance was significantly higher than the static cyclic fatigue resistance in continuous rotary instruments, but not in reciprocating instruments.

In the experimental condition where the ascending speed was higher than the descending speed, the dynamic cyclic fatigue resistance was significantly higher than the static cyclic fatigue resistance in continuous rotary instruments, but not in reciprocating instruments.

This study compared the accuracy, sensitivity, and specificity of different imaging diagnostic protocols, cone-beam computed tomography (CBCT) and digital periapical radiography (DPR), in identifying separated endodontic instruments in filled root canals.

One hundred eight root canals from 36 mandibular molars were prepared and obturated. Of these, 84 were filled without separated instruments, and 24 were filled with the presence of a separated instrument (stainless steel hand file or reciprocating instrument). Subsequently, different CBCT imaging protocols were acquired i-CAT Classic (ICC) (0.25-mm isotropic voxel), i-CAT Next Generation (ICN) (0.125-mm isotropic voxel), and PreXion 3D (PXD) (0.09-mm isotropic voxel). Moreover, a DPR exam was obtained (08mA, 70kVp, and exposure time of 0.2seconds). Two calibrated endodontists evaluated each image for the presence or absence of fractured files on a 5-point scale, ranging from definitely absent to definitely present. BMS202 manufacturer The accuracy, sensitivity, and specificity measures for each method were estimated.