Dentistry Medical and Health News Headlines

Terminal restriction fragment length polymorphism analysis of the microflora in necrotic teeth of patients irradiated in the head and neck region.

J Endod. 2008 Sep;34(9):1048-51

Authors: Hommez GM, Verhelst R, Vaneechoutte M, Claeys G, De Moor RJ

This study evaluated the microflora in root canals of necrotic teeth after radiotherapy of the head and neck region. The microbial composition of samples taken from necrotic root canals in patients treated with irradiation of the head and neck (group A, n = 13) and in healthy controls (group B, n = 11) was analyzed by terminal restriction fragment-length polymorphism (T-RFLP) analysis. A total of 50 different terminal restriction fragment lengths (T-RFs) (each representing one or more bacterial species) were detected in the T-RFLP profiles, 44 in group A and 28 in group B. A mean of 13.2 T-RFs per sample were detected in group A and 6.6 T-RFs were present per sample for group B (p < 0.05). Twenty-two different T-RFs (mainly subspecies of Lactobacillus spp., Capnocytophaga spp., and Actinomyces spp.) found in group A were not found in group B. In conclusion, the diversity of root canal microflora increases significantly after head-neck radiotherapy.

PMID: 18718363 [PubMed - in process]

Radiographic investigation of location and angulation of curvatures in human maxillary incisors.

J Endod. 2008 Sep;34(9):1052-6

Authors: Willershausen B, Kasaj A, Tekyatan H, Roehrig B, Briseno B

The aim of this radiographic study was to evaluate the degree and location of root canal curvatures of human maxillary incisors. A total of 286 extracted human maxillary incisors (145 central and 141 lateral incisors) were included in this investigation. Exclusion criteria were teeth with extensive carious lesions, restorations, and root canal treatment. For this in vitro study, the teeth were fixed in a special device and digitally x-rayed with the parallel technique. The distances from the cementoenamel junction (CEJ) to the first curvature and the according angle were recorded. The results were analyzed descriptively, and p values were calculated with the Wilcoxon Mann-Whitney test. The mean distance between the CEJ and the first curvature of the central maxillary incisors was 10.4 mm (standard deviation [SD] +/- 2.8) and that of the lateral incisors was 11.1 mm (SD +/- 3.0). Most of the central incisors (right: 94.2%, left: 98.7%) and all of the lateral incisors exhibited curvatures. Statistically significant differences between central and lateral maxillary incisors could be observed regarding the canal curvature locations (p = 0.016) and the angle values (p < 0.001), but there was no statistical difference between the right and the left side. The results showed the high percentage of root canal curvatures in maxillary incisors with a mean curvature located 10.7 mm apical from the CEJ. These findings are important to minimize failures during post insertion.

PMID: 18718364 [PubMed - in process]

The effect of mineral trioxide aggregate on the mineralization ability of rat dental pulp cells: an in vitro study.

J Endod. 2008 Sep;34(9):1057-60

Authors: Yasuda Y, Ogawa M, Arakawa T, Kadowaki T, Saito T

The aim of this study was to investigate the effect of mineral trioxide aggregate (MTA) on cell viability and mineralization ability of rat dental pulp cells. The pulp capping materials, such as MTA, Dycal (Dentsply Caulk, Milford, DE), and Superbond C&B (SB; Sun Medical, Shiga, Japan) were placed on transwell inserts and cultured with rat dental pulp cells. MTA and SB exhibited no cytotoxicity, whereas almost all cells had died after 72 hours of culture with Dycal. MTA significantly stimulated mineralization by 60% compared with the control. MTA and Dycal significantly upregulated by two-fold the level of bone morphogenetic protein (BMP)-2 messenger RNA expression compared with the control. Furthermore, MTA increased BMP-2 protein production by about 40%, whereas Dycal significantly reduced it. Although MTA and Dycal increased the concentration of extracellular calcium by about 0.4 mmol/L, SB had no effect. These results suggest that BMP-2 may play an important role in mineralization stimulated by MTA.

PMID: 18718365 [PubMed - in process]

Nicotine inhibits mineralization of human dental pulp cells.

J Endod. 2008 Sep;34(9):1061-5

Authors: Yanagita M, Kashiwagi Y, Kobayashi R, Tomoeda M, Shimabukuro Y, Murakami S

Nicotine is a major component of tobacco smoke, and signals via nicotinic acetylcholine receptors (nAChR). However, little is known about the effects of nicotine on human dental pulp cells (HDPCs). In this study, we assessed the effects of nicotine on mineralization in HDPCs. We confirmed messenger RNA expression of nAChR subunits and examined the effects of nicotine on expression of extracellular matrices (ECMs), alkaline phosphatase (ALP) activity, and mineralized nodule formation by HDPCs. Gene expression of nAChR subunits alpha1, alpha2, alpha4, alpha5, alpha6, alpha7, beta1, beta2, and beta4 was detected in HDPCs. Interestingly, the messenger RNA expression of dentin matrix acidic phosphoprotein-1, bone sialoprotein, and ALP activity were significantly reduced in nicotine-treated HDPC. In addition, mineralized nodule formation, which was examined by alizarin red staining, was also inhibited in HDPCs by the same treatment. These results indicate that nicotine suppresses the cytodifferentiation and mineralization of HDPCs, possibly via nAChR.

PMID: 18718366 [PubMed - in process]

The expression of macrophage and neutrophil elastases in rat periradicular lesions.

J Endod. 2008 Sep;34(9):1072-6

Authors: Morimoto T, Yamasaki M, Nakata K, Tsuji M, Nakamura H

Macrophage elastase and neutrophil elastase are involved in tissue destruction in periradicular lesions. The purpose of this study was to examine these elastases immunohistochemically during development of periradicular lesions induced in rat mandibular first molar by pulpal exposure for 7, 14, 21, 28, and 42 days. Histologically, periapical inflammation developed from 7 to 21 days and then subsided after 28 days. The area of these lesions gradually increased from 7 to 28 days and subsequently decreased at 42 days. Macrophage elastase was first detected at 7 days and predominantly shown from 14 to 28 days, whereas neutrophil elastase gradually increased from 14 to 28 days. Macrophage elastase was significantly greater than neutrophil elastase from 7 to 21 days. These results suggest that macrophage elastase was enhanced from an early stage during the development of these lesions and that neutrophil elastase was related to the expansion of periapical tissue destruction including bone resorption.

PMID: 18718368 [PubMed - in process]

Differentially Expressed Protein Profile of Human Dental Pulp Cells in the Early Process of Odontoblast-like Differentiation In Vitro.

J Endod. 2008 Sep;34(9):1077-84

Authors: Wei X, Wu L, Ling J, Liu L, Liu S, Liu W, Li M, Xiao Y

Dental pulp cells (DPCs) are capable of differentiating into odontoblasts that secrete reparative dentin after pulp injury. The molecular mechanisms governing reparative dentinogenesis are yet to be fully understood. Here we investigated the differential protein profile of human DPCs undergoing odontogenic induction for 7 days. Using two-dimensional differential gel electrophoresis coupled with matrix-assisted laser adsorption ionization time of flight mass spectrometry, 23 protein spots related to the early odontogenic differentiation were identified. These proteins included cytoskeleton proteins, nuclear proteins, cell membrane-bound molecules, proteins involved in matrix synthesis, and metabolic enzymes. The expression of four identified proteins, which were heteronuclear ribonuclear proteins C, annexin VI, collagen type VI, and matrilin-2, was confirmed by Western blot and real-time real-time polymerase chain reaction analyses. This study generated a proteome reference map during odontoblast-like differentiation of human DPCs, which will be valuable to better understand the underlying molecular mechanisms in odontoblast-like differentiation.

PMID: 18718369 [PubMed - in process]

In Vitro Cytotoxicity Evaluation of a Self-adhesive, Methacrylate Resin-based Root Canal Sealer.

J Endod. 2008 Sep;34(9):1085-8

Authors: Pinna L, Brackett MG, Lockwood PE, Huffman BP, Mai S, Cotti E, Dettori C, Pashley DH, Tay FR

This study compared the cytotoxicity of MetaSEAL (Parkell Inc, Farmington, NY), a methacrylate resin-based sealer with an epoxy resin-based (AH Plus Jet; Dentsply Caulk, Milford, DE) and a zinc oxide-eugenol-based sealer (Pulp Canal Sealer; SybronEndo, Orange, CA). Five-millimeter diameter disks prepared from the respective sealer and disks prepared from Teflon (negative control) and polymethyl methacrylate (positive control) were placed in direct contact with a rat osteosarcoma (ROS) 17/2.8 rat osteoblast-like cell line at six intervals after setting completely at 72 hours and for 5 succeeding weeks after the disks were immersed in simulated body fluid. Succinate dehydrogenase activity was evaluated by using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide assay. All sealers exhibited severe toxicity at 72 hours, after which toxicity decreased gradually over the experimental period except for Pulp Canal Sealer, which remained severely toxic. MetaSEAL was more toxic than AH Plus Jet during the first week. Both were similar to the toxicity profile of the positive control after the first week, which was probably diffusion controlled.

PMID: 18718370 [PubMed - in process]

Factors affecting temperature rise on the external root surface during ultrasonic retrieval of intracanal separated files.

J Endod. 2008 Sep;34(9):1089-92

Authors: Madarati AA, Qualtrough AJ, Watts DC

Temperature rise (TR) on the external root surface during ultrasonic removal of separated files (SFs) from 50 lower incisors roots of 10-mm length was investigated. CPR ultrasonic tips (Obtura-Spartan, Fenton, MO) were used dry to retrieve F2 ProTaper (Dentsply, Surrey, UK) segments fractured 2.5 mm from the coronal access in five groups: CPR2, CPR5, and CPR6 at power setting 1 and CPR5 at power settings 2.5 and 5. Temperature changes were inspected at 30-second intervals up to 120 seconds at three different sites: two at mesiodistal and buccolingual surfaces adjacent to the most coronal aspect of the SF and the third adjacent to the most apical aspect. Overall, the highest mean TR was at the buccolingual root surface followed by that at the mesiodistal and the more apical site surfaces. At power setting 1, CPR6 produced a significantly lower TR than CPR5, and both can be used for 120 and 60 seconds, respectively. Power setting 5 is not recommended for the removal of SF because this induces a hazardous TR.

PMID: 18718371 [PubMed - in process]

The Development of Carbonate-containing Apatite/Collagen Composite for Osteoconductive Apical Barrier Material.

J Endod. 2008 Sep;34(9):1096-100

Authors: Takenaka Y, Iijima M, Kawano S, Akita Y, Yoshida T, Doi Y, Sekine I

The current report describes the properties of a new apical barrier material formulated from carbonate-containing apatite (CAp) and collagen. CAp particles of around 50 nm were deposited on reconstituted collagen fibers. CAp/col with about 60 wt % CAp (corresponding to apatite content of bone) was obtained after 1 day of calcification. CAp content increased up to about 80 wt % in a 15-day calcification reaction. CAp/col was composed of fine calcified collagen fibers. The crystallinity and Ca/PO(4) ratio of CAp were comparable to those of bone apatite. The mixture of CAp/col and saline reached a pH of about 9. The optimum powder-to-liquid ratio (P/L) to set into a root canal was determined to be 1.2. Furthermore, the mixture (P/L = 1.2) condensed in a root canal was liquid permeable. Thus, the CAp/col was expected as an apical barrier material with osteoconductivity.

PMID: 18718373 [PubMed - in process]

Differences in aluminum equivalent values of endodontic sealers: conventional versus digital radiography.

J Endod. 2008 Sep;34(9):1101-4

Authors: Baksi BG, Sen BH, Eyuboglu TF

The aims of this study were to compare film and digital radiography in assessing the radiopacities of root canal sealers and to establish the relation in aluminum equivalent values of different methods. Standard disks of 5 different sealers were exposed together with an aluminum step wedge by using occlusal films and storage phosphor plates. Optical density of the sealers was evaluated by transmission densitometry, and mean gray values were determined by digital analysis. The data were analyzed by using two-way analysis of variance (P = .05). Pairwise comparisons were made by using Tukey post hoc and paired t tests (P = .05). The order from the most radiopaque to the most radiolucent sealer was the same for both methods; however, aluminum equivalent values determined by transmission densitometry were significantly higher (P < .01). Aluminum equivalent values of the 2 radiographic methods were 7%-20% different. The International Standards Organization standard for the radiopacity of dental root canal sealing materials needs modifications for digital systems.

PMID: 18718374 [PubMed - in process]

An ex vivo evaluation of a gutta-percha filling technique when used with two endodontic sealers: analysis of the filling of main and lateral canals.

J Endod. 2008 Sep;34(9):1105-10

Authors: Venturi M

The aim of this study was to evaluate both the precision of filling and the extension of voids in main root canals as well as filling of lateral canals after using a two-phase filling technique with two sealers. Twenty-four maxillary and 26 mandibular molars were selected and randomly assigned to two groups. Root canals were instrumented and then filled using the vertical compaction with the apical backfilling technique, with Pulp Canal Sealer (EWT) in group "A" and AH Plus in group "B." After clearing, voids within the filled main canals were measured by using a stereomicroscope. In addition, visible lateral canals were counted, each unfilled space was measured, and five ratings (0-4) were fixed. In both groups, in the most apical 4 mm of main canals, where gutta-percha was cold compacted, lesser voids (p </= 0.05) were found than in the middle-coronal thirds backfilled with thermomechanical compaction. In group "B," more precision (p </= 0.05) and lesser voids (p </= 0.05) were found than in group "A." Regarding lateral canals, better filling scores (p </= 0.05) were found in group "B" than in group "A." In both groups, better filling scores (p </= 0.05) were found at the coronal levels than at the middle ones and at the middle levels than at the apical ones.

PMID: 18718375 [PubMed - in process]

A comparison of five radiographic systems to d-speed film in the detection of artificial bone lesions.

J Endod. 2008 Sep;34(9):1111-4

Authors: Hadley DL, Replogle KJ, Kirkam JC, Best AM

The purpose of this study was to compare three direct digital sensors (Kodak 6100 [Rochester, NY], Schick CDR [Long Island City, NY], and Dexis PerfectSize [Alpharetta, GA]), a phosphor plate system (OpTime; Milwaukee, WI), and F-speed film to standard D-speed film in the detection of artificial bone lesions prepared in mandible bone sections. Artificial bone lesions were prepared at varying depths in the cortical bone. Radiographs were randomly presented to nine different observers. Logistic regression analysis indicated significant differences in lesion detection among the radiographic systems at the mean percentage of cortical bone remaining. The Kodak filtered, Schick filtered, OpTime unfiltered, Schick unfiltered, and Dexis filtered images were significantly better at lesion detection compared with D-speed film.

PMID: 18718376 [PubMed - in process]

Augmenting the antibiofilm efficacy of advanced noninvasive light activated disinfection with emulsified oxidizer and oxygen carrier.

J Endod. 2008 Sep;34(9):1119-23

Authors: George S, Kishen A

In this study, we tested the hypothesis that the inclusion of an oxidizer and oxygen carrier in the photosensitization formulation would facilitate comprehensive disinfection of matured endodontic biofilm by light-activated disinfection (LAD). Photosensitizing formulations containing methylene blue (MB) and an oxygen carrier alone (perfluorodecahydronaphthalene) (PF1) or in combination with oxidizer (H(2)O(2)) (PF2) or their emulsions formed with triton-X100 (Bio-Rad Laboratories, Hercules, CA) in different proportions (PF3 and PF4) were tested for photochemical properties and damage to the biofilm structure using confocal laser scanning microscopy. Conventional chemomechanical preparation, LAD using MB in water, and LAD using MB in emulsion (PF4) were also conducted on 10-week-old Enterococcus faecalis biofilm within root canals. MB in emulsion (PF4) was overall the most effective photosensitizer formulation for photooxidation, generation of singlet oxygen (p = 0.001), and in disinfecting biofilm bacteria. Advanced noninvasive LAD using a photosensitizer formulation containing oxidizer and oxygen carrier disrupted the biofilm matrix and facilitated comprehensive inactivation of biofilm bacteria. This modified photosensitizer formulation will have potential advantages in endodontic disinfection.

PMID: 18718378 [PubMed - in process]

Apical actinomycosis as a continuum of intraradicular and extraradicular infection: case report and critical review on its involvement with treatment failure.

J Endod. 2008 Sep;34(9):1124-9

Authors: Ricucci D, Siqueira JF

This article reports a case of extraradicular actinomycosis that clearly formed a continuum with the intraradicular infection. Histobacteriologic and histopathologic analyses of the root tip and attached apical periodontitis lesion obtained by surgery from a tooth with persistent disease were performed to look for the possible reasons for persistent disease. Although no stainable bacteria were observed in the apparently well-treated main canal, apical ramifications were clogged with dense bacterial biofilms that were contiguous to extraradicular actinomycotic aggregates. A critical review of the literature revealed that there is no clear evidence that apical actinomycosis is indeed an independent entity leading to persistent apical periodontitis lesions.

PMID: 18718379 [PubMed - in process]

Mineral trioxide aggregate as repair material for furcal perforation: case series.

J Endod. 2008 Sep;34(9):1130-3

Authors: Pace R, Giuliani V, Pagavino G

The purpose of treating furcal perforation is to seal the artificial communication between the endodontic space and the periradicular tissue to prevent alveolar bone resorption and damage to the periodontal ligament. These complications are not infrequent in cases of furcal and/or old perforations, which show a worse prognosis than fresh, small, coronal, and apical perforations. Mineral trioxide aggregate (MTA) is widely used to seal perforations because of its biocompatibility and sealability. Ten cases of furcal perforation were selected at the department of Endodontics, University of Florence. All the perforations were cleaned with NaOCl, EDTA, and ultrasonic tips and sealed with MTA without internal matrix. Finally, the teeth were endodontically treated and coronally restored. Clinical and radiographic follow-ups were done at 6 months, 1 year, 2 years, and 5 years. After 5 years, the absence of periradicular radiolucent lesions, pain. and swelling along with functional tooth stability indicated a successful outcome of sealing perforations in 9 out of 10 teeth. One patient dropped out of the study after the 1-year follow-up and could not be contacted for further recalls. The results confirm that MTA without matrix provides an effective seal of root perforations and clinical healing of the surrounding periodontal tissue.

PMID: 18718380 [PubMed - in process]

Comprehensive treatment of the infected maxillary lateral incisor with an accessory root.

J Endod. 2008 Sep;34(9):1134-7

Authors: Yavuz MS, Keleş A, Ozgöz M, Ahmetoğlu F

Rare anatomic anomalies may occur in the dentition and can affect treatment decisions and prognosis. Accurate diagnosis and therapy performed at the highest level can result in predictable success in these cases. This case report shows the clinical and radiographic findings and successful treatment (nonsurgical and surgical) of a combined apical and marginal periodontal inflammatory lesion of a maxillary lateral incisor with an accessory root.

PMID: 18718381 [PubMed - in process]