Dimensional variability of nonstandardized greater taper finger spreaders with matching gutta-percha points

Furcation groove of maxillary first premolar, thickness, and dentin structures

INTRODUCTION

Few studies mention the presence of furcation grooves in the palatal aspect of buccal roots in upper first premolars. Anatomic characteristics like external grooves or root curvatures predispose teeth to weakening during post placement. Roots with a large number of external sulci show more canal variations. Previous research found that the palatal wall is on average less than 1mm. There is a direct relation between the volume of dental structures and the capacity to resist occlusal loads. The purpose of this study was to evaluate the changes in dentin thickness and structures adjacent to the furcal groove.

METHODS

The percentage that represented furcation groove in the buccal root was specified. The sample size selected was n=20. Three horizontal slices were made to the buccal root, coronal, middle, and apical. The angles of the grooves and dentin thickness were measured with a profile projector.

RESULTS

In the coronal third, the depth of the groove was correlative with dentin thickness negatively, ie, while the depth increased, palatal dentin thickness decreased or vice versa. In the coronal and middle thirds, the palatal wall showed average dentin width smaller than the buccal. In some cases, the thickness was less than 1mm. In the apical third, palatal dentin thicknesses showed higher averages than the buccal. Structural changes were observed in dentin adjacent to the furcation groove. These results are discussed in the context of other research. Methodologic differences do not enable comparative studies.

CONCLUSIONS

Dentin thickness corresponding to the furcal groove is variable; it presents structural changes and must be taken into account in endodontic and prosthetic procedures.

Separation with zwitterionic hydrophilic interaction liquid chromatography improves protein identification by matrix-assisted laser desorption/ionization-based proteomic analysis

Comprehensive proteomic analyses necessitate efficient separation of peptide mixtures for the subsequent identification of proteins by mass spectrometry (MS). However, digestion of proteins extracted from cells and tissues often yields complex peptide mixtures that confound direct comprehensive MS analysis. This study investigated a zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) technique for the peptide separation step, which was verified by subsequent MS analysis. Human serum albumin (HSA) was the model protein used for this analysis. HSA was digested with trypsin and resolved by ZIC-HILIC or conventional strong cation exchange (SCX) prior to MS analysis for peptide identification. Separation with ZIC-HILIC significantly improved the identification of HSA peptides over SCX chromatography. Detailed analyses of the identified peptides revealed that the ZIC-HILIC has better peptide fractionation ability. We further demonstrated that ZIC-HILIC is useful for quantitatively surveying cell surface markers specifically expressed in undifferentiated embryonic stem cells. These results suggested the value of ZIC-HILIC as a novel and efficient separation method for comprehensive and quantitative proteomic analyses.

Effects of autoclaving on dimensional qualities and physical properties (flexural rigidity and brittleness) of newly developed root canal filling point made of polypropylene (FLEX POINT NEO)

In this study, we investigated the effects of 10 cycles of conventional autoclaving (121 degrees C, 20 min) on the dimensional integrity and physical properties (flexural rigidity and brittleness) of a newly developed root canal filling point made of polypropylene (FLEX POINT NEO). We measured the diameters of autoclave-sterilized and non-treated polypropylene points (020 through 070) and calculated the incidence of deviation from ISO specifications (6877.4.4.1, 1995). In order to ascertain physical properties, we tested autoclave-sterilized and non-treated polypropylene points (030, 050 and 070) for flexural rigidity. This was done by evaluating deflection value when a load was placed at the free tip-end of the point and brittleness in accordance with ISO specifications (6877.6.5.2). Ten cycles of autoclaving showed no significant effect on the diameters of the polypropylene points. All the polypropylene points in both the non-treated and the autoclave-sterilized groups met ISO specifications in terms of dimensional integrity of diameter. In the autoclave-sterilized group, 030 and 050 polypropylene points showed a slight decrease in flexural rigidity (3.4% in 030, 10.0% in 050). In terms of brittleness, none of polypropylene points showed any sign of fracture.