The multiprotein complexes involved in active dis-ruption of chromatin structure, homologous to yeast SWI/SNF complex, have been described for human and Drosophila cells. In all SWI/SNF-class complexes characterised so far, one of the key components is the SNF5-type protein. Here we describe the isolation of a plant (Arabidopsis thaliana ) cDNA encoding a 27 kDa protein which we named BSH, with high homology to yeast SNF5p and its human (INI1) and Drosophila (SNR1) counterparts as well as to other putative SNF5-type proteins from Caenorhabditis elegans, fish and yeast. With 240 amino acids, the Arabidopsis BSH is the smallest SNF5-type protein so far identified. When expressed in Saccharomyces cerevisiae, the gene for BSH partially complements the snf5 mutation. BSH is, however, unable to activate transcription in yeast when tethered to DNA. The gene for BSH occurs in single copy in the Arabidopsis genome and is ubiquitously expressed in the plant. Analysis of the whole cell and nuclear protein extracts with antibodies against recombinant BSH indicates that the protein is localised in nuclei. Transgenic Arabidopsis plants with markedly decreased physiological level of the BSH mRNA, resulting from the expression of antisense messenger, are viable but exhibit a distinctive phenotype characterised by bushy growth and flowers that are unable to produce seeds.

BackgroundThe success of endodontic treatment is greatly affected by the location of the root canals. The purpose of this study was to evaluate the root and canal morphology of permanent maxillary first and second molars in a Polish population using cone-beam computed tomography scanning.MethodsCone-beam computed tomography (CBCT) scans of maxillary first and second molars the maxilla were examined. The number of roots and root canals, and the frequency of additional canals (MB2) in the mesiobuccal root canals were determined. The results were subjected to statistical analysis using the chi-square test or the chi-square test with Yates’ correction.ResultsA total of 112 CBCT images of maxillary first (n = 185) and second molars (n = 207) from 112 patients were analyzed. All the maxillary first molars had three roots (100%). The majority of maxillary second molars had three roots (91.8%), 5.8% had two roots and 2.4% had one root. A statistically significant difference was observed between the numbers of roots in the maxillary first and second molars (p < 0.01). A statistically significant difference was also found in the distribution of the number of canals in the maxillary first and second molars (p < 0.001). The majority of maxillary first molars had four root canals (59.5%), while 40.5% had three root canals. Most maxillary second molars had three root canals (70%). Additional canals (MB2) in the mesiobuccal roots were detected significantly more frequently in the maxillary first molars than the second molars (p = 0.000) and more frequently in men than in women (p < 0.05). A higher prevalence of two canals in the mesiobuccal roots in maxillary second molars occurred in patients aged between 31 and 40 years than in patients aged between 21 and 30 years. In the maxillary first molars, the prevalence of the MB2 canal in the mesiobuccal root was almost equally distributed in the two age groups (21–30 and 31–40 years).ConclusionWithin the limitations of this study, it can be concluded that there are differences in the number and configuration of roots and root canals between maxillary first and second molars in the studied patients of a Polish population.

The aim of this study was to evaluate the root and canal morphology of permanent maxillary first premolars in a Polish population using cone-beam computed tomography scanning (CBCT) and to compare the classifications by Vertucci and Ahmed et al. Images of 350 maxillary first premolars were analyzed. Scans were obtained from 226 patients: 131 women and 95 men. The root canal configurations were classified according to Vertucci and a new system by Ahmed et al. In addition, the number of roots and the level where roots bifurcated were identified. The results were submitted to statistical analysis. Most maxillary first premolars had two roots (69.1%). Most bifurcations were located in the coronal part of the root (44.2%) and the least in the apical part (15.3%). Bifurcation in the coronal part of the root was observed more often in the teeth of men than women. In turn, bifurcation in the central or apical part was significantly more common in women than in men. The most common canal configuration of the maxillary first premolars was type IV (78.2%) according to Vertucci and 2FPB1P1 (65.4%) according to the new classification. Among the remaining cases, almost all types of canals described by Vertucci, and many combinations of codes given in the new classification were demonstrated. The maxillary first premolars displayed a wide range of root and canal anatomical variations. The new system for classifying canal morphology based on Ahmed et al. is more accurate than the Vertucci classification.

The aim of this study was to evaluate the sealing ability of three different canal filling techniques. Sixty-four roots of extracted human maxillary anterior teeth were prepared using ProTaper® rotary instruments. The specimens were then randomly divided into 3 experimental groups (n = 16) and 2 control groups (n = 8). The root canals were filled using cold lateral compaction (CLC group), continuous wave condensation technique using the Elements Obturation Unit® (EOU group), and ProTaper obturators (PT group). For the negative control group, 8 roots were filled using lateral compaction as in the CLC group, and the teeth were covered twice with a layer of nail varnish (NCG group). Another 8 roots were filled using lateral compaction, but without sealer, and these were used as the positive control (PCG group). A glucose leakage model was used for quantitative evaluation of microleakage for 24 hours and 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 weeks. No significant difference in the cumulative amount of leakage was found between the three experimental groups at all observation times. The lateral condensation of cold gutta-percha can guarantee a similar seal of canal fillings as can be achieved by using thermal methods, in the round canals.

The aim was to evaluate the morphology of maxillary second premolars. The root canal configurations were classified according to Vertucci and a new system by Ahmed et al. based on CBCT images. In addition, the number of roots and the level where they bifurcated were identified, and morphological measurements were performed based on anatomical landmarks. Single-rooted forms were most common.Bifurcation occurred most often in the middle part of the root. The most common canal configuration was type I according to Vertucci and code 1 SP 1 according to the new classification. The measurements showing the results were as follows (mm): palatal cusp/buccal cusp/the lowest point of the occlusal surface to pulp chamber ceiling 6.18/6.54/4.77; the ceiling of the pulp chamber was found at the CEJ in 92.28% of the specimens. The maxillary second premolars tended to be single-rooted and with one root canal.