Pre-eruptive intracoronal resorption in a third upper molar: clinical, tomographic and histological analysis

Radiolucent or hypodense lesions in the crown of unerupted teeth may be due to pre-eruptive intracoronal resorption. Clinicians must be aware of this risk so that they can diagnose and appropriately treat this condition. The purpose of this study is to present a well-documented clinical case of pre-eruptive intracoronal resorption in an impacted third upper left molar of a 63 year old female patient. This was an unexpected finding, which occurred after cone-beam computed tomography was used to investigate the first upper left molar, which had an acute periradicular abscess. A multidisciplinary team followed up the case to describe clinical, radiographic and histological findings. The available treatment options were discussed, and the tooth extraction was the option chosen. Previous case studies describing such resorption in third upper molars have not been reported. This case shows that all permanent teeth in a pre-eruptive stage must be analysed radiographically to detect early pre-eruptive intracoronal resorption.

Similar sealability between bioceramic putty ready-to-use repair cement and white MTA

This study was designed to assess the ability to prevent glucose penetration of a bioceramic putty ready-to-use repair cement comparing to white mineral trioxide aggregate (WMTA). After root canal instrumentation, the apical 3 mm of maxillary incisors were resected and root-end cavities with depth of 3 mm were prepared with ultrasound and filled with the tested materials (15 roots per group). All roots were mounted in a double chamber system to assess glucose penetration using 15 psi pressure application. After 1 h, glucose concentrations in the lower chamber were measured following an enzymatic reaction. Four roots were used as controls. The Mann-Whitney test verified differences in glucose leakage between groups and the Tukey's test was used for multiple comparisons. Significance level was set at 5%. There was no significant difference in glucose leakage between iRoot BP Plus and White MTA groups. iRoot BP Plus had a similar ability to that of white MTA in preventing glucose leakage as a root-end filling material.

Assessing accumulated hard-tissue debris using micro-computed tomography and free software for image processing and analysis

INTRODUCTION

The accumulation of debris occurs after root canal preparation procedures specifically in fins, isthmus, irregularities, and ramifications. The aim of this study was to present a step-by-step description of a new method used to longitudinally identify, measure, and 3-dimensionally map the accumulation of hard-tissue debris inside the root canal after biomechanical preparation using free software for image processing and analysis.

METHODS

Three mandibular molars presenting the mesial root with a large isthmus width and a type II Vertucci's canal configuration were selected and scanned. The specimens were assigned to 1 of 3 experimental approaches: (1) 5.25% sodium hypochlorite + 17% EDTA, (2) bidistilled water, and (3) no irrigation. After root canal preparation, high-resolution scans of the teeth were accomplished, and free software packages were used to register and quantify the amount of accumulated hard-tissue debris in either canal space or isthmus areas.

RESULTS

Canal preparation without irrigation resulted in 34.6% of its volume filled with hard-tissue debris, whereas the use of bidistilled water or NaOCl followed by EDTA showed a reduction in the percentage volume of debris to 16% and 11.3%, respectively. The closer the distance to the isthmus area was the larger the amount of accumulated debris regardless of the irrigating protocol used.

CONCLUSIONS

Through the present method, it was possible to calculate the volume of hard-tissue debris in the isthmuses and in the root canal space. Free-software packages used for image reconstruction, registering, and analysis have shown to be promising for end-user application.

Mapping large extensions of flat dentin through digital microscopy: introduction to the method and possible applications

PURPOSE

To introduce a mapping method to characterize large dentin surfaces using digital microscopy and to discuss the advantages and possible applications of the method.

MATERIALS AND METHODS

Twenty unerupted third molars were sectioned transversally exposing coronal dentin surfaces. The microscopic mosaic method was used to generate a large field image with the resolution necessary to measure characteristics of dentin tubules. The AxioVision 4.7 software was used to control a motorized optical microscope and the process of acquiring approximately 400 small images to generate each dentin mosaic. An image analysis routine measured the number of tubules (NT) and the ratio between the total area of tubules and the area of the mosaic - the area fraction (AF) - of each mosaic. An automatic procedure transformed the mosaic image into a color map, providing a direct visual representation of tubule density through colors. The dentin maps were used for a comparative qualitative analysis of tubule density distribution of each sample.

RESULTS

The results for NT (92450 to 196029 tubules/sample) and AF (4.12% to 11.10%) demonstrated a wide variation among dentin samples. The maps confirmed the microstructure variety, also revealing strong local variations in tubule density within each sample.

CONCLUSION

The mapping method was able to perform dentin morphology characterization and is a valuable tool for producing a baseline for dentin adhesion studies. The method could be also useful in determining the real contribution of dentin structures to the final adhesion quality.

Isolation and taxonomy of filamentous fungi in endodontic infections

INTRODUCTION

The purpose of this study was to research the presence of filamentous fungi in the root canals of teeth with pulp necrosis and periapical lesions and to perform the taxonomic study of the isolates.

METHODS

Samples collected from 60 root canals with sterile absorbent paper points were inoculated in Sabouraud dextrose agar supplemented with chloramphenicol. The material was cultured from 7-14 days at room temperature to observe mycelial growth. Samples with growth were seeded in media specific for microculture (CYA agar, malt extract agar, or potato dextrose agar). Taxonomy was evaluated by macroscopic examination and optical microscopy.

RESULTS

Filamentous fungi were isolated in situ from 17 of 60 samples (28.3%). Considering the positive root canal isolates, the genus Aspergillus was isolated from 7 samples (41%); 4 species were identified: Aspergillus ustus, A. granulosus, A. niger, and A. sydowii. Emericella quadriluniata, sexual form of Aspergillus, was isolated from 1 sample. Penicillium species (Penicillium implicatum, P. micsynvisk, P. lividum, and P. citrionigrum) were isolated from 4 samples (24%). Fusarium species (Fusarium moniliforme and F. melanochorum) were isolated from 2 samples (12%). The species Aureobasidium pullulans, Exophiala jeanselmei, Eurotium amstelodame, and Cladosporium sphaerospermum were isolated from 1 sample each.

CONCLUSIONS

The root canals of teeth with pulp necrosis and periapical lesions might present positive culture for filamentous fungi.

Bacterial leakage in root canals filled with calcium hydroxide paste associated with different vehicles

This in vitro study evaluated, using a bacterial leakage model, whether intracanal medication with calcium hydroxide [Ca(OH)2]-based pastes prepared with different vehicles, has inhibitory effect on corono-apical leakage of bacteria. Forty instrumented human canines were dressed with Ca(OH)2 p.a. associated with: G1 = distilled water; G2 = polyethylene glycol (PG); G3 = PG + CMCP; and G4 = glycerin. Five teeth with intact crowns served as negative controls and 5 instrumented teeth without temporary dressing served as positive controls. All teeth were mounted in a 2-chamber apparatus and then exposed to human saliva for 63 days. Leakage was recorded when turbidity was observed in the lower chamber. Fifty percent of the samples of G1 and G2, 10% of G3 and 80% of G4 were fully contaminated after 9 weeks. Statistically significant differences were observed with paired comparisons G3 and G4 (p=0.0069), with G3 achieving better seal against bacterial leakage than G4.

Microbiological evaluation of primary endodontic infections in teeth with and without sinus tract

AIM

To examine the microbiological status of primary endodontic infections in teeth with and without a sinus tract.

METHODOLOGY

Samples were collected by means of a size 15 H-type file and two sterile paper points from 30 cases of primary endodontic infections with (n = 15) or without (n = 15) a sinus tract. The presence of 40 bacterial species was determined by the checkerboard DNA-DNA hybridization method.

RESULTS

The species found at the highest levels and prevalence were Fusobacterium nucleatum sp. vincentii, Porphyromonas gingivalis, Veillonella parvula, Enterococcus faecalis, Campylobacter gracilis and Neisseria mucosa. Total bacterial counts were similar between teeth with (44 x 10(5)) and without (50 x 10(5)) a sinus tract (t-test: P > 0.05). E. faecalis, Streptococcus anginosus, Capnocytophaga sputigena and Capnocytophaga gingivalis had significantly higher counts in the absence of sinus tract (Mann-Whitney test, P < 0.05). Higher levels of P. gingivalis and Fusobacterium nucleatum sp. nucleatum were observed in cases with a sinus tract. Leptotrichia buccalis (OR = 1.83; CI 95%) and Porphyromonas endodontalis (OR = 2.15; CI 95%) were associated with an increased chance of subjects having a sinus tract.

CONCLUSIONS

Primary endodontic infections were associated with a large variety of bacterial species. Specific differences between the composition of the microbiota of primary root canal infections were observed in cases with or without a sinus tract.

Evaluation of the microbiota of primary endodontic infections using checkerboard DNA-DNA hybridization

BACKGROUND/AIMS

The aim of this study was to evaluate the composition of the microbiota of primary endodontic infections in 111 selected cases of single-rooted teeth with necrotic pulp.

METHODS

Samples were collected from the root canals using #15 Hedströen-type files and two sterile paper points, which were introduced 1 mm short of the apical foramen. The presence, levels, and proportions of 40 different bacterial species in each sample were determined using DNA probes and checkerboard DNA-DNA hybridization techniques.

RESULTS

The mean number of species per sample was 22. Enterococcus faecalis (89.3%), Campylobacter gracilis (89.3%), Leptotrichia buccalis (89.3%), Neisseria mucosa (87.5%), Prevotella melaninogenica (86.6%), Fusobacterium nucleatum ssp. vincentii (85.7%), Eubacterium saburreum (75.9%), Streptococcus anginosus (75%), and Veillonella parvula (74.1%) were the most prevalent species. The species found in highest mean counts (over 10(5)) were F. nucleatum ssp. vincentii (13.14 x 10(5)), E. saburreum (5.67 x 10(5)), E. faecalis (5.38 x 10(5)), N. mucosa (4.19 x 10(5)), V. parvula (3.63 x 10(5)), C. gracilis (3.46 x 10(5)), Treponema socranskii (3.34 x 10(5)), Porphyromonas endodontalis (2.96 x 10(5)), Porphyromonas gingivalis (2.85 x 10(5)), Micromonas micros (2.81 x 10(5)), Prevotella nigrescens (2.68 x 10(5)) and Fusobacterium nucleatum ssp. nucleatum (2.64 x 10(5)). Most of these species were also found in high proportions.

CONCLUSIONS

Our results suggest that several bacterial species considered to be oral pathogens seem to be implicated in the etiology of primary endodontic infections.

Sealing ability of oval-shaped canals filled using the System B heat source with either gutta-percha or Resilon: an ex vivo study using a polymicrobial leakage model

OBJECTIVE

The present study systematically compared the sealing ability of oval-shaped canals filled using the System B heat source with either gutta-percha/sealer or Resilon/Epiphany.

STUDY DESIGN

Eighty mandibular incisors with oval-shaped canals were selected after buccolingual and mesiodistal radiographs and divided into 3 experimental groups (n = 20). The teeth were obturated as follows: G1: gutta-percha/Pulp Canal Sealer EWT using cold lateral condensation; G2: gutta-percha/Pulp Canal Sealer EWT using the System B heat source; and G3: Resilon tips and Epiphany sealer using the System B heat source. The roots were mounted in a bacterial leakage model and the system was checked daily during the following 9 weeks. The log rank test was used to analyze the leakage data at intervals of 3, 6, and 9 weeks. The level of significance was set at P < .05.

RESULTS

Seven samples of G1 (35%) and 5 samples (20%) each of G2 and G3 were fully contaminated after 9 weeks. Data showed no significant difference between traditional gutta-percha/sealer and Resilon/Epiphany (P > .05). However, both materials showed significant difference to cold lateral condensation when System B heat source was used (P < .05).

CONCLUSIONS

The results demonstrated that Resilon/Epiphany combination do not improve the bacterial leakage resistance compared with traditional gutta-percha/sealer fillings.

The influence of organic load on the antimicrobial activity of different concentrations of NaOCl and chlorhexidine in vitro

AIM

To evaluate bacterial growth after contact with sodium hypochlorite (NaOCl; 1 and 5%) and chlorhexidine (CHX; 0.12, 0.5 and 1%) in vitro with or without the addition of organic material (bovine serum albumin (BSA) 0.5%).

METHODOLOGY

Bacterial samples (American Type Culture Collection (ATCC)) of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis and Fusobacterium nucleatum were kept in contact with each irrigating solution for varying intervals of time: immediately (t0), 5 min (t5), 15 min (t15) and 30 min (t30). Each test was repeated 10 times. In half of the specimens, 0.5% BSA was added as organic material in an attempt to simulate the organic tissue present in the root canal system. Bacterial growth under appropriate condition of incubation was evaluated and compared for each microorganism at all time intervals.

RESULTS

A 0.12% CHX solution did not eliminate E. faecalis at any time interval. One percent CHX eliminated all strains, as did both NaOCl concentrations. BSA did not interfere substantially with the antimicrobial activity of any of the irrigating solutions.

CONCLUSIONS

Under the condition of this study, a 0.12% CHX solution was ineffective at killing E. faecalis.

Increased abundance of alternatively spliced forms of D2 dopamine receptor mRNA after denervation

The existence of two molecular forms of D2 dopamine receptors suggests that differences in the distribution or regulation of the two forms could be exploited for the pharmacological treatment of disease. Using probes selective for each alternatively spliced variant of D2 receptor mRNA, we determined that both variants were widely distributed in rat brain and pituitary but that the ratio of the forms varied among regions. mRNA for the 444-amino acid-long variant, D2(444), was the most abundant form in pituitary and neostriatum. Intermediate levels of both D2(444) mRNA and the short form, D2(415), were detected in midbrain, and low levels of D2(444) and D2(415) mRNAs were detected in all other regions examined, including hippocampus, cerebellum, and cortex. The D2(444)/D2(415) ratio was generally lower in the regions of low expression than in pituitary and neostriatum. Dopamine-depleting lesions increased the density of D2 receptors in the denervated neostriatum by 29% without altering the affinity of the receptors for [3H]spiperone. The proliferation of receptors appeared to be due to a lesion-induced increase of up to 120% in the abundance of both variants of mRNA in the neostriatum.

Aspergillus nidulans contains a single actin gene which has unique intron locations and encodes a gamma-actin

The single actin gene from the filamentous fungus Aspergillus nidulans has been isolated and characterized. The only other organism reported to contain just one actin gene is another Ascomycete, the budding yeast Saccharomyces. The nucleotide sequence of the A. nidulans actin gene predicts a polypeptide containing the N-terminal sequence identifying the gamma-actin isotype. Until now this characteristic N terminus has only been reported to occur in vertebrate actin sequences. A monospecific anti-gamma-actin antiserum recognizes a single 42-kDa band in immunoblots of total Aspergillus protein. None of the six introns in the A. nidulans actin gene sequence aligns precisely with those found in other actin genes. One, unlike other known actin introns, is located in the 3'-untranslated region of the gene. The 5' and 3' ends of the gene have been characterized. The Aspergillus actin gene has a heterogeneous transcript size due to the presence of several different 3' termini. Of four characterized polyadenylated transcripts, only the longest contains a typical AATAAA polyadenylation signal near its 3' terminus. Using an integrative plasmid containing Aspergillus actin sequences and the pyr4 gene from Neurospora, the A. nidulans actin gene has been mapped to the first chromosome.

Calmodulin-dependent multifunctional protein kinase in Aspergillus nidulans

A Ca2+/calmodulin (CaM)-dependent multifunctional protein kinase has been isolated from Aspergillus nidulans and purified to homogeneity. Unlike any CaM-dependent multifunctional protein kinase described previously, the native enzyme from Aspergillus behaves as a monomer. The calculated molecular weight is 41,200. NaDodSO4/PAGE reveals a single protein band with an apparent Mr of 51,000. Two-dimensional isoelectric focusing/NaDodSO4/PAGE of the purified enzyme showed one major and one minor more acidic Coomassie blue-stained spot, both of which bind 125I-labeled calmodulin in a calcium-dependent manner. The kinase is autophosphorylated in a calcium- and CaM-dependent manner, yielding an increase in the amount and number of more acidic forms of the enzyme. The Aspergillus kinase catalyzes the Ca2+/CaM-dependent phosphorylation of known substrates of type II Ca2+/CaM-dependent protein kinases, including glycogen synthase, microtubule-associated protein 2, synapsin, tubulin, gizzard myosin light chain, and casein. Cross-reactivity between antiserum raised against native rat brain protein kinase II and 125I-labeled Aspergillus kinase has been detected. Two forms of CaM have been isolated from Aspergillus nidulans, both of which activate the Aspergillus kinase at lower concentrations than that required for activation by bovine brain CaM.

Aspergillus nidulans beta-tubulin genes are unusually divergent

Aspergillus nidulans has two beta-tubulin genes: benA, which is involved in both vegetative growth and asexual sporulation, and tubC, which is involved mainly in asexual sporulation. Both genes have now been cloned and sequenced. benA encodes a polypeptide of 447 amino acids (aa) and tubC encodes one of 449 aa. The two polypeptides differ by 78 aa residues but the net charge for the two proteins remains the same. The divergence between the amino acid sequences of the Aspergillus beta-tubulins is greater than that for any other two beta-tubulins yet described in the same organism. The benA gene has eight introns and the tubC gene has five, all of which correspond in amino acid position to introns in benA. The positions of some of these introns are conserved in other beta-tubulin genes. The 5'-splice site, internal, and 3'-splice site consensus sequences are similar to those found in other fungal introns. The transcriptional start points for each gene have been determined using primer extension and/or S1 nuclease mapping. Neither the benA gene nor the tubC gene contains a TATA sequence in its 5'-flanking region. The tubC gene has two repeated upstream sequences which are not found in benA. The sites of polyadenylation have been determined for each gene using S1 nuclease mapping. Neither gene contains a polyadenylation signal, AATAAA, typical of other eukaryotic genes.