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Dentinal Tubules (dentinal + tubule)
Selected AbstractsSealing evaluation of the cervical base in intracoronal bleachingDENTAL TRAUMATOLOGY, Issue 6 2003Luciane Dias De Oliveira Abstract,,, Discoloration of non-vital teeth is an esthetic deficiency frequently requiring bleaching treatment. The purpose of this study was to evaluate in vitro the cervical base efficacy in order to prevent or to minimize the leakage along the root canal filling and into the dentinal tubules. Thirty-eight extracted single-root human teeth were used, which were biomechanically prepared, filled, and divided into three experimental groups: G1, a cervical base was applied (3 mm of thickness) below the cemento-enamel junction, with resin-modified glass-ionomer cement (Vitremer); G2, the base was done with glass-ionomer cement (Vidrion R); and G3 (Control), did not receive any material as base. A mixture of sodium perborate and hydrogen peroxide 30% was placed inside the pulp chamber for 3 days, and the access opening was sealed with Cimpat. This procedure was repeated thrice. Soon after this, a paste of calcium hydroxide was inserted into the pulp chamber for 14 days. All teeth were covered with two layers of sticky wax, except the access opening, and immersed in blue India Ink for 5 days. The results did not show statistically significant differences between the three groups concerning the leakage inside the dentinal tubules. Regarding the apical direction, a statistical difference (anovaP < 0.05) was observed among the experimental group G1 and control group G3. No statistically significant difference was observed between G2 and G3 groups. Therefore, the placement of a cervical base before internal bleaching procedures is still recommended. [source] Timeliness and effectiveness in the surgical management of persistent post-treatment periapical pathosisENDODONTIC TOPICS, Issue 1 2005MIN-KAI WU Common problems that cause persistent post-treatment periapical pathosis include infection remaining in the apical inaccessible areas, extraradicular infection including apically extruded dentine debris with bacteria present in dentinal tubules, radicular true cysts, foreign body reactions, inadequate non-surgical root canal treatment with or without iatrogenically altered root canal morphology, and vertical root fractures. Inadequate root canal treatment may be corrected non-surgically, while more complex problems may require surgical intervention. The important factors that warrant a successful surgery include good quality of the orthograde root canal treatment, deep retrograde preparation of the apical canal, and carefully cleaning and filling of the exposed isthmuses and accessory canals. Ideally, apical surgery and orthograde retreatment are performed simultaneously. In a recent study, 97% of the lesions including large ones of >10 mm in diameter healed completely within 1 year after surgical intervention. Of the teeth that showed ,complete healing' at 4 years more than 85% already ,completely healed' at 2 years; thus, the endodontic post-treatment disease might be treated surgically or non-surgically within 2 years after the previous treatment. [source] Spectroscopic investigation of the function of aqueous 2-hydroxyethylmethacrylate/glutaraldehyde solution as a dentin desensitizerEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2006Chuangye Qin Fourier-transform (FT)-Raman and -infrared (IR) spectroscopy were employed to investigate the function of the aqueous 2-hydroxyethylmethacrylate/glutaraldehyde solution (Gluma) as a desensitizer. 2-Hydroxyethylmethacrylate (HEMA), glutaraldehyde (GA), and the mixture of HEMA/GA (i.e. Gluma) were used to interact with dentin, collagen, hydroxyapatite (HAP), and bovine serum albumin (BSA) individually. All the interactions were monitored by an FT-Raman spectrometer. FT-IR spectroscopy was also used in this study. The results show that HEMA could be absorbed by dentin and collagen; GA could cross-link collagen and BSA; and when BSA was added to Gluma, polymerization of HEMA occurred. The results suggest that Gluma acts as a desensitizer whereby, first, GA reacts with part of the serum albumin in dentinal fluid, which induces a precipitation of serum albumin, then, second, a reaction of GA with serum albumin induces polymerization of HEMA. The function of Gluma as a desensitizer to block dentinal tubules occurs via these two reactions. [source] Effect of endodontic irrigation on bonding of resin cement to radicular dentinEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2005Mikako Hayashi The influence of endodontic irrigation on shear bond strengths of resin cement to radicular dentin was investigated. Human radicular dentin blocks were divided into four groups and subjected to one of four endodontic irrigations: ethylenediaminetetraacetic acid (EDTA) group, 17% EDTA for 60 s; EDTA/sodium hypochlorite (NaOCl) group, 17% EDTA for 60 s followed by 10 ml of 5% NaOCl for 15 s; NaOCl group, 10 ml of 5% NaOCl for 15 s; and control group, no treatment. Morphological changes of dentin surface after endodontic irrigation were observed by scanning electron microscopy (SEM). A resin block was bonded to the radicular dentin after irrigation using resin cement with either wet-bonding (Uni-Etch/One-Step; Bisco) or self-etching (Tyrian SPE/One-Step Plus; Bisco) adhesives. Shear bond strengths were measured and the penetration of resin tags into dentinal tubules at resin,dentin interface was observed by SEM. With the wet-bonding system, the shear bond strengths for the EDTA/NaOCl group, in which dentinal tubules openings and uniform resin tag penetration into dentinal tubules were observed, were significantly higher than the EDTA and control groups. With the self-etching system, the shear bond strengths were significantly lower in the EDTA group compared with the NaOCl and control groups. The effects of endodontic irrigation on the bonding of resin cement to radicular dentin depended on the dentin bonding system used. [source] Surface characteristics of dentin experimentally exposed to hydrofluoric acidEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2003Thomas Pioch The purpose of this study was to test the effect of hydrofluoric acid (HF) on the surface characteristics of dentin in vitro. Dentin was exposed in 50 human molars and divided into five groups according to different etching schedules: (i) no etching, (ii) 15 s HF, (iii) 15 s H3PO4, (iv) 15 s HF and 15 s H3PO4, (v) 15 s H3PO4 and 15 s HF. Teeth were examined under a scanning electron microscope equipped with energy-dispersive X-ray (EDX) or two layers of fluorescence-labeled primer followed by the composite were applied, and the teeth were sectioned and examined using confocal laser scanning microscopy (CLSM). With scanning electron microscopy, no openings of dentinal tubules were found in groups (i), (ii), and (iv). In group (v) only a few tubules were opened and in group (iii) the smear layer was completely removed and tubules appeared open. The EDX analysis revealed that fluoride was incorporated into the dentin surface when HF was used. With CLSM, distinct hybrid layers could be detected only in group (iii). In group (v) the hybrid layer appeared less established compared with group (iii). No dentin hybridization was found in groups (i), (ii), and (iv). It is concluded that HF has the ability to close the openings of dentin tubules which were opened due to etching by phosphoric acid and cannot dissolve the smear layer. [source] The effect of ultrasonically activated irrigation on reduction of Enterococcus faecalis in experimentally infected root canalsINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2010A. J. Harrison Harrison AJ, Chivatxaranukul P, Parashos P, Messer HH. The effect of ultrasonically activated irrigation on reduction of Enterococcus faecalis in experimentally infected root canals. International Endodontic Journal, 43, 968,977, 2010. Abstract Aim, To investigate the ability of an ultrasonically activated irrigating system to eliminate bacteria from the canal wall and dentinal tubules of extracted teeth. Methodology, One hundred and thirty roots of intact human teeth were inoculated with Enterococcus faecalis for 4 weeks. The straight roots were randomly allocated to a baseline group (n = 25) or subjected to routine cleaning and shaping procedures (n = 105). Two sub-groups of prepared canals were then additionally exposed either to ultrasonic irrigation with 1% sodium hypochlorite (NaOCl) for 1 min (n = 35) or to 1 week of intracanal medication with calcium hydroxide [Ca(OH)2] (n = 35). All roots were processed for light microscopy (Brown and Brenn stain) (n = 28) or scanning electron microscopy (n = 7). Triplicate histological sections from each of the apical, middle and coronal thirds were scored for bacterial presence using pre-defined criteria. Results, Baseline bacterial penetration resulted in an average depth of tubule invasion of 151 ,m. Routine canal preparation failed to eliminate bacteria consistently from either the canal wall or within tubules. Ultrasonic irrigation and medication with Ca(OH)2 consistently eliminated bacteria from the canal wall (P < 0.001) compared with baseline and routine treatment, and more frequently from dentinal tubules than routine canal preparation alone (P < 0.01). Ultrasonic irrigation was as effective in bacterial reduction as 1 week of intracanal medication with Ca(OH)2, but neither led to complete bacterial elimination in all roots. Conclusions, Ultrasonically activated irrigation for 1 min with 1% NaOCl after canal preparation in straight root canals is potentially an effective supplementary step in microbial control. [source] The smear layer in endodontics , a reviewINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2010D. R. Violich Abstract Root canal instrumentation produces a layer of organic and inorganic material called the smear layer that may also contain bacteria and their by-products. It can prevent the penetration of intracanal medicaments into dentinal tubules and influence the adaptation of filling materials to canal walls. This article provides an overview of the smear layer, focusing on its relevance to endodontics. The PubMed database was used initially; the reference list for smear layer featured 1277 articles, and for both smear layer dentine and smear layer root canal revealed 1455 publications. Smear layer endodontics disclosed 408 papers. A forward search was undertaken on selected articles and using some author names. Potentially relevant material was also sought in contemporary endodontic texts, whilst older books revealed historic information and primary research not found electronically, such that this paper does not represent a ,classical' review. Data obtained suggests that smear layer removal should enhance canal disinfection. Current methods of smear removal include chemical, ultrasonic and laser techniques , none of which are totally effective throughout the length of all canals or are universally accepted. If smear is to be removed, the method of choice seems to be the alternate use of ethylenediaminetetraacetic acid and sodium hypochlorite solutions. Conflict remains regarding the removal of the smear layer before filling root canals, with investigations required to determine the role of the smear layer in the outcomes of root canal treatment. [source] Pulp revascularization of necrotic bilateral bicuspids using a modified novel technique to eliminate potential coronal discolouration: a case reportINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2009K. Reynolds Abstract Aim, To present a case report in which the pulp of two bilateral mandibular premolars with dens evaginatus were revascularized using a modified novel technique to avoid undesired crown discolouration. Summary, Recently, regeneration of necrotic pulps has become an alternative conservative treatment option for young permanent teeth with immature roots and is a subject of great interest in the field of endodontics. This novel procedure exploits the full potential of the pulp for dentine deposition and produces a stronger mature root that is better able to withstand the forces than can result in fracture. However, the current protocol has potential clinical and biological complications. Amongst them, crown discolouration, development of resistant bacterial strains and allergic reaction to the intracanal medication. In the case presented, a modified technique to avoid undesired crown discolouration was applied sealing the dentinal tubules of the chamber, thus avoiding any contact between the tri-antibiotic paste and the dentinal walls. Key learning points, ,,Sealing the dentinal tubules of the chamber prevents the undesirable crown discolouration produced by tri-antibiotic medication whilst maintaining the revascularization potential of the pulp. ,,Further research is warranted to seek an alternative infection control protocol capable of preventing possible allergic reactions and development of resistant strains of bacteria, as well as a biological material capable of inducing angiogenesis and allow a more predictable scaffold and tissue regeneration. [source] Residual bacteria in root apices removed by a diagonal root-end resection: a histopathological evaluationINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2008S. Lin Abstract Aim, To assess bacteria in the apical portion of the root end after 45° root-end resection in teeth with persistent periapical lesions. Methodology, The study included 27 apical root segments from patients with persistent periapical lesions. Histological sections of the coronal part of the amputated root segment were stained with Brown and Brenn to detect the presence of bacteria in the main root canal and/or in irregular root spaces and dentinal tubules. The quality of each root canal filling was evaluated using preoperative radiographs of filling, length of root filling as assessed from the distance between its apical end and the radiographic apex, diameter of apical preparation, and presence of apical perforations or deviations from the root canal. Two endodontists, blinded to the bacteriological results, independently evaluated the radiographs. Results, Bacteria were present in 23 (85.2%) specimens: five in only the main canal (21.7%), 10 in only the dentinal tubules and irregular spaces (43.5%), and eight in both irregular spaces and dentinal tubules and in the main root canal (34.8%). No correlation was found between the technical quality of the root filling assessed radiographically and bacterial presence in the central canal or irregular areas. Conclusions, Infected irregular areas were found in the root tips of teeth with persistent periapical lesions. This was found regardless of the radiographic quality of the root filling. Diagonal, 45° root-end resection may expose such contaminated irregularities to the periapical tissue. [source] Hemin nutritional stress inhibits bacterial invasion of radicular dentine by two endodontic anaerobesINTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2007R. M. Love Abstract Aim, To determine if anaerobic bacteria routinely found in infected dentine and root canals require the presence of heme in the environment in order for them to invade dentinal tubules. Methodology, Noncarious, unrestored human teeth with single root canals were prepared for invasion experiments and soaked in either TSB-M supplemented with hemin (5 ,g mL,1) (n = 12 roots), TSB-M media (n = 12 roots) or TSB-M media followed by hemin soak (n = 12 roots) for 2 days, then inoculated with either Prevotella intermedia ATCC 25611 or Peptostreptococcus micros ATCC 33270 and incubated anaerobically for 14 days. Roots were prepared for light microscopy, stained with Brown and Brenn or antisera raised to the bacteria, and invasion within tubules assessed using a tubule invasion index (TI). Data were analysed using Student's t -test and Mann,Whitney U -test. Results,Prevotella intermedia (TI = 0.7 ± 0.04) and P. micros (TI = 0.96 ± 0.08) showed low invasion when grown in the presence of hemin with cells generally restricted to the superficial 20 ,m of the tubules, whilst neither bacteria invaded tubules (TI = 0) when hemin was absent from the growth media (P < 0.01). Conclusions, Hemin was required in the growth medium for P. intermedia and P. micros to invade dentinal tubules. [source] Efficacy of various concentrations of NaOCl and instrumentation techniques in reducing Enterococcus faecalis within root canals and dentinal tubulesINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2006V. B. Berber Abstract Aim, To evaluate the efficacy of 0.5%, 2.5% and 5.25% sodium hypochlorite (NaOCl) as intracanal irrigants associated with hand and rotary instrumentation techniques against Enterococcus faecalis within root canals and dentinal tubules. Methodology, A total of 180 extracted human premolar teeth were infected for 21 days with E. faecalis. The specimens were divided into 12 groups, as follows: group 1: 5.25% NaOCl + Hybrid technique (Valdrighi et al. 1998); group 2: 5.25% NaOCl + nickel,titanium (NiTi) rotary technique 4 mm shorter than the apex (by FOP-UNICAMP); group 3: 5, 25% NaOCl + NiTi rotary technique (Hero 642); group 4: 2.5% NaOCl +Hybrid technique; group 5: 2.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 6: 2.5% NaOCl + NiTi rotary technique (Hero 642); group 7: 0.5% NaOCl + Hybrid technique; group 8: 0.5% NaOCl + NiTi rotary technique 4 mm shorter than the apex; group 9: 0.5% NaOCl + NiTi rotary technique (Hero 642); group 10: sterile saline solution + Hybrid technique; group 11: sterile saline solution + NiTi rotary technique 4 mm shorter than the apex; group 12: sterile saline solution + NiTi rotary technique (Hero 642). Canals were sampled before and after preparation. After serial dilution, samples were plated onto brain heart infusion (BHI) agar, and the colony forming units (CFU) that were grown were counted. The teeth were sectioned into three thirds and dentine chips were removed from the canals with conical burs. The samples obtained with each bur were immediately collected into test tubes containing BHI broth, and were incubated at 37 °C and plated onto BHI agar. The CFU were counted and analysed. Results, At all depths and thirds of the root canals and for all techniques used, 5.25% NaOCl was shown to be the most effective irrigant solution tested when dentinal tubules were analysed, followed by 2.5% NaOCl. No differences among concentrations in cleaning the canals were found. Conclusions, Especially at higher concentrations, NaOCl, was able to disinfect the dentinal tubules, independent of the canal preparation technique used. [source] Recovery of Enterococcus faecalis after single- or multiple-visit root canal treatments carried out in infected teeth ex vivoINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2005N. Vivacqua-Gomes Abstract Aim, To assess the presence of Enterococcus faecalis after root canal treatment in single or multiple visits in an ex vivo model. Methodology, Forty-five premolar teeth were infected ex vivo with E. faecalis for 60 days. The canals were then prepared using a crowndown technique with System GT and Gates,Glidden burs and irrigated with 2% chlorhexidine gel. The specimens were divided into five groups (G1, G2, G3, G4 and G5) according to the time elapsed between chemical,mechanical preparation and root canal filling, the irrigant solution used and the use or nonuse of a calcium hydroxide intra-canal medicament. The teeth were then root-filled and incubated for 60 days at 37 °C. Dentine chips were removed from the canal walls with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing Brain,Heart Infusion broth. These samples were placed onto agar plates and colony forming units were counted after 24 h at 37 °C. Data were ranked and analysed using the Kruskal,Wallis statistical test. Results,Enterococcus faecalis was recovered from 20% (three of 15 specimens) of G1 (chlorhexidine irrigation and immediate root filling in a single visit), 25% (four of 15 specimens) of G2 (chlorhexidine irrigation and filling after 14 days use of a calcium hydroxide dressing in multiple visits), 40% (two of five specimens) of G3 (chlorhexidine irrigation and filling after 7 days), 60% (three of five specimens) of G4 (saline irrigation and filling after 7 days) and from 100% (five of five specimens) of G5 (saline irrigation and immediate filling without sealer). Conclusions, Neither single- nor multiple-visit root canal treatment ex vivo, eliminated E. faecalis completely from dentinal tubules. Up to 60 days after root filling, E. faecalis remained viable inside dentinal tubules. When no sealer was used, E. faecalis presented a higher growth rate. [source] In vitro antimicrobial effect of chlorhexidine-impregnated gutta percha points on Enterococcus faecalisINTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2004J. N. Lui Abstract Aim, To evaluate the in vitro antimicrobial effect of chlorhexidine-impregnated gutta percha points, Roeko activ point (Roeko, Langenau, Germany) on Enterococcus faecalis. Methodology, Human maxillary premolar roots were prepared with .04 rotary ProFile instruments to a master apical file size 40, autoclave-sterilized and then infected with E. faecalis (ATCC 29212) for 3 weeks. Baseline controls were carried out verifying negligible effects of plain gutta percha cones on E. faecalis. Subsequent to intracanal placement of calcium hydroxide, ,activ points' or saline (positive control) and the 2-week incubation in 54 root specimens, dentine sampling at depths of 100 and 250 µm was carried out using .04 rotary ProFile instruments at sizes 60 and 90 to assess the quantity of bacteria present. Inactivating agents were used prior to sampling and the colony-forming units (CFU) of E. faecalis were then plate-counted after culturing. Statistical analysis was completed using the paired t -test. Results, In comparison to the positive control, treatment with calcium hydroxide (P = 0.000 and 0.000) or activ points (P = 0.000 and 0.002) produced significantly lower colony counts of E. faecalis at dentine depths of 100 and 250 µm, respectively. Calcium hydroxide (2.10 × 102 CFU mL,1) was significantly more effective than activ points (1.58 × 103 CFU mL,1) at 100 µm (P = 0.013), but not at 250 µm (P = 0.353). Neither of these two medications was able to eliminate E. faecalis completely. Conclusions, Chlorhexidine-impregnated activ points did not possess an in vitro inhibitory activity strong enough to eliminate E. faecalis completely from infected dentinal tubules. [source] Penetration of propylene glycol into dentineINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2002E. V. Cruz Abstract Cruz EV, Kota K, Huque J, Iwaku M, Hoshino E. Penetration of propylene glycol into dentine. International Endodontic Journal, 35, 330,336, 2002. Aim This study aimed to evaluate penetration of propylene glycol into root dentine. Methodology Safranin O in propylene glycol and in distilled water were introduced into root canals with and without artificial smear layer. Dye diffusion through dentinal tubules was determined spectrophotometrically. The time required for dye to exit through the apical foramen using propylene glycol and distilled water as vehicles was also determined. The extent and areas of dye penetration on the split surfaces of roots were assessed using Adobe Photoshop and NIH Image Software. Results Propylene glycol allowed dye to exit faster through the apical foramen. The area and depth of dye penetration with propylene glycol was significantly greater than with distilled water (P < 0.0001). Smear layer significantly delayed the penetration of dye. Conclusion Propylene glycol delivered dye through the root canal system rapidly and more effectively indicating its potential use in delivering intracanal medicaments. [source] The structure of dentine in the apical region of human teethINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2001I. A. Mjör Abstract Aim To study the structure of the apical region of human teeth with emphasis on dentinal tubules and their branches. Methodology This descriptive histological study employed demineralized stained sections for light microscopy, demineralized unstained sections for scanning electron microscopy, and undemineralized, acid-etched specimens for confocal tandem scanning microscopy. Results The apical portion of human teeth showed marked variations in structure, including accessory root canals, areas of resorption and repaired resorptions, occasional attached, embedded and free pulp stones, varied amounts of irregular secondary dentine, and even cementum-like tissue lining the apical root canal wall. The apex often deviated from the long axis of the root canal. Primary dentinal tubules were irregular in direction and density. Some areas were devoid of tubules. Conclusions The irregular and variable structure of the apical region of human teeth represent special challenges during endodontic therapy. Obturation techniques based on the penetration of adhesives into dentinal tubules are unlikely to be successful and adhesive techniques must depend on impregnation of a hybrid layer. [source] Bacterial invasion of dentinal tubules beneath apparently intact but hypomineralized enamel in molar teeth with molar incisor hypomineralizationINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 5 2008TOBIAS G. FAGRELL Background., The most common problems for a patient with molar incisor hypomineralization (MIH) are the collapse of enamel and cavitations, loss of fillings, and secondary caries, but most of all, severe hypersensitivity. Objective., The aim of this paper was therefore to histologically study possible bacterial invasion of dentinal tubules beneath apparently intact, but hypomineralized enamel in permanent molars with MIH. Material and methods., Five extracted permanent first molars diagnosed with MIH were fixated, demineralized, and sagittally serially sectioned in a bucco-lingual direction in a microtome with a thickness of 4,5 µm. Sections were stained with a modified Brown and Benn staining for bacteria, unstained sections were analysed in field emission SEM. Results., Stained sections from the cuspal areas, below the hypomineralized enamel, the staining indicated the presence of bacteria in the dentinal tubules. The HTX staining showed that the pulp in sections without any findings was normal and free from bacteria or infiltrates from inflammatory cells. In sections where bacteria were found in the cuspal areas or deeper in the dentin, a zone of reparative dentin was found, and in sections from one tooth, the coronal pulp showed an inflammatory reaction with inflammatory cells. In sections adjacent to those without any bacterial staining, the SEM analyses revealed empty dentinal tubules without any odontoblast processes or signs of bacteria. When odontoblast processes were found, the dentinal tubules were filled with bacteria located on the surface of the odontoblast processes. In some areas, a large number of tubules were found with bacteria. No bacteria were found close to the pulp. The odontoblast processes appeared larger in areas where bacteria were found. Conclusions., The presence of bacteria in the dentinal tubules and inflammatory reactions in the pulp indicate that oral bacteria may penetrate through the hypomineralized enamel into the dentin, thus possibly contribute to hypersensitivity of teeth with MIH. [source] Evaluation of penetration and adaptation of three different sealers: a SEM studyJOURNAL OF ORAL REHABILITATION, Issue 9 2003S. Sevimay Summary, In this study, dentinal penetration and adaptation of three endodontic sealers were evaluated by using scanning electron microscope (SEM). Seventeen recently extracted, human maxillary anterior teeth were used. After the crowns were removed from the cementoenamel junction, the root canals were instrumented. The teeth were then randomly divided into three groups of five roots each and two teeth were used as controls. The smear layer was removed with EDTA and NaOCl. The canals were obturated with AH 26, CRCS, RSA sealers and gutta-percha using lateral condensation technique. Each root was sectioned longitudinally and then prepared for SEM evaluation. The SEM results showed that AH 26 was the best sealer penetrating into dentinal tubules and adapted to dentinal walls when compared with the CRCS and RSA. The CRCS and RSA occluded the orificies of dentinal tubules. The RSA showed that the penetration was less than AH 26 and more than CRCS. [source] Migration of mercury from dental amalgam through human teethJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2008Hugh H. Harris Exposure to mercury from dental amalgams, with possible negative health effects, has generally been considered to occur via either erosion or evaporation directly from the surface of fillings, followed by ingestion. The aim of this study was to determine the relative importance of the direct migration of mercury through the tooth as an alternative exposure pathway. X-ray fluorescence imaging has been used to determine quantitatively the spatial distribution of Hg, Ca, Zn and Cu in sections of human teeth that had been filled with amalgam for more than 20 years. X-ray absorption near-edge spectroscopy (XANES) was also employed to gain chemical information on the mercury present in the teeth. Hg (up to ,10,mg,g,1) and Zn (>100,mg,g,1) were detected in the teeth several millimetres from the location of the amalgams. At high resolution, Hg showed higher concentrations in dentinal tubules while Zn was generally evenly distributed. XANES showed that the chemical form of Hg that had migrated into the tooth had been altered from that present in the amalgam. The differing spatial distributions of Hg and Zn suggest distinct transport mechanisms for the two metals, presumably chemical for Zn and initially physical for Hg. Subsequent oxidation of Hg may lead to a loss of mobility or the development of a secondary transport mechanism. Most importantly the detection of Hg in areas of the tooth that once contained an active bloodstream and in calculus indicates that both exposure pathways should be considered as significant. [source] Host collagen signal induces antigen I/II adhesin and invasin gene expression in oral Streptococcus gordoniiMOLECULAR MICROBIOLOGY, Issue 2 2003Catherine Heddle Summary Microbial interactions with host molecules, and programmed responses to host environmental stimuli, are critical for colonization and initiation of pathogenesis. Bacteria of the genus Streptococcus are primary colonizers of the human mouth. They express multiple cell-surface adhesins that bind salivary components and other oral bacteria and enable the development of polymicrobial biofilms associated with tooth decay and periodontal disease. However, the mechanisms by which streptococci invade dentine to infect the tooth pulp and periapical tissues are poorly understood. Here we show that production of the antigen I/II (AgI/II) family polypeptide adhesin and invasin SspA in Streptococcus gordonii is specifically upregulated in response to a collagen type I signal, minimally the tri-peptide Gly-Pro-Xaa (where Xaa is hydroxyproline or alanine). Increased AgI/II polypeptide expression promotes bacterial adhesion and extended growth of streptococcal cell chains along collagen type I fibrils that are characteristically found within dentinal tubules. These observations define a new model of host matrix signal-induced tissue penetration by bacteria and open the way for novel therapy opportunities for oral invasive diseases. [source] The cervical wedge-shaped lesion in teeth: a light and electron microscopic studyAUSTRALIAN DENTAL JOURNAL, Issue 3 2009TJ Daley Abstract Background:, The cervical non-carious wedged-shaped lesion is controversial in that its aetiology may involve attrition, erosion, abrasion and stress-corrosion (abfraction). This study examined the histopathology of anterior teeth with cervical wedge-shaped lesions by light and electron microscopy to elucidate their pathogenesis. Methods:, Ten undecalcified human teeth with cervical lesions were available for investigation. Patency of the dentine tubules was tested using red dye penetration from the pulp chamber. The morphology of normal and sclerotic dentine adjacent to the cervical wedge-shaped lesions was investigated by scanning electron microscopy. The numbers and diameters of dentinal tubules were measured at different levels beneath the surfaces of the lesions. Results:, The gross and microscopic features of the worn teeth were described. Red dye penetration tests showed white tracts of sclerotic tubules contrasted with red tracts of patent tubules. Numbers of tubules per square area and diameters of patent and sclerotic tubules varied at different levels within the dentine due to deposits of intratubular dentine. Conclusions:, The cervical wedge is shaped by interactions between acid wear, abrasion and dentinal sclerosis. No histopathological evidence of abfraction was found. Clinical diagnosis, conservation and restoration of non-carious cervical lesions need to take into account the extent of sclerotic dentine beneath wedge-shaped lesions. [source] Light activated disinfection: an alternative endodontic disinfection strategyAUSTRALIAN DENTAL JOURNAL, Issue 2 2009Z Lim Abstract Background:, An improved light activated disinfection technique utilizing a specific photosensitizer formulation, liquid optical-conduit, oxygen-carrier and light energy of appropriate wavelength has been introduced recently. This study tested the efficacy of this improved light activated disinfection on ex vivo biofilms of Enterococcus faecalis at two different stages of maturation. Methods:, Eighty-five tooth sections were prepared and endodontic biofilm of E. faecalis were grown within the root canal. In stage 1, conventional light activated disinfection (LAD), chemical disinfectant (sodium hypochlorite) and improved LAD were tested on four-day-old (immature) biofilms. In stage 2, conventional LAD, improved LAD and chemomechanical disinfection (alone and in combination with improved LAD) were tested on four-week-old (mature) biofilms. Results:, Sodium hypochlorite and improved LAD showed the ability to significantly inactivate bacteria in four-day-old biofilms when compared to the control and LAD (p < 0.05). Inactivation of bacteria from deeper dentine was higher in improved LAD than sodium hypochlorite. In four-week-old biofilms, a combination of chemomechanical disinfection and improved LAD produced significant bacterial killing compared to either chemomechanical disinfection or improved LAD alone. Conclusions:, This study highlighted the potential of improved LAD to kill bacteria within dentinal tubules. In combination with chemomechanical preparation, the improved LAD significantly inactivated four-week-old biofilm bacteria. [source] Laser-activated fluoride treatment of enamel as prevention against erosionAUSTRALIAN DENTAL JOURNAL, Issue 3 2007J. Vlacic Abstract Background: Erosion is the loss of dental hard tissues from an acidic challenge, often resulting in exposure of dentinal tubules and hypersensitivity to environmental stimuli. Laser-activated fluoride (LAF) therapy with 488nm laser energy has been shown previously to increase the resistance of human enamel and dentine to acid dissolution. The aims of this study were to investigate the action spectrum of LAF in protecting tooth enamel from softening in response to an erosive challenge, and to examine for any temperature change with the treatment. Materials and Methods: Buccal and lingual surfaces of extracted sound molar and premolar teeth were used to prepare matched pairs of enamel slabs (N=10 per group). After application of 1.23% neutral sodium fluoride gel (12 300ppm F ion), slab surfaces were lased with 488, 514.5, 532, 633, 670, 830 or 1064nm wavelength (energy density 15J/cm2; spot size 5mm), then exposed to an erosive challenge (1.0M HCl for five minutes). The Vicker's hardness number (VHN) was recorded before fluoride gel application and again following the acid challenge. Negative controls did not receive laser exposure. Results: All wavelengths of laser light examined provided a protective LAF effect against softening, compared with the negative control surfaces. Conclusion: From these findings, we conclude that the action spectrum of the LAF effect extends across the visible spectrum, providing protection to dental enamel from an erosive challenge. [source] Scanning electron microscopy evaluation of the hard tissue barrier after pulp capping with calcium hydroxide, mineral trioxide aggregate (MTA) or ProRoot MTAAUSTRALIAN ENDODONTIC JOURNAL, Issue 2 2009Eduardo Galia Reston dds Abstract The aim of this study was to investigate the morphology and localisation of calcium hydroxide- and mineral trioxide aggregate (MTA)-induced hard tissue barriers after pulpotomy in dogs' teeth. Pulpotomies were performed on maxillary and mandibular premolars of five dogs. The teeth were assigned into three groups according to the pulp-capping agent used. The pulpal wounds were capped with calcium hydroxide (Ca(OH)2, control), MTA or ProRoot MTA, and the cavities were restored with amalgam. After a 90-day follow-up period, the dogs were euthanised and the teeth were examined under scanning electron microscopy (SEM). An image-processing and analysis software was used to delimit the perimeters of the root canal area and the hard tissue barrier to determine the percentage of root canal obliteration. SEM data were used to assess the morphology, localisation and extension of the reparative hard tissue barriers. ProRoot MTA was statistically different from MTA and Ca(OH)2 (P < 0.05) regarding tissue barrier morphology. Localisation data showed that ProRoot MTA was significantly different from Ca(OH)2 (P < 0.05) and similar to MTA (P > 0.01; P > 0.05). No statistically significant difference (P > 0.01; P > 0.05) was observed between MTA and Ca(OH)2. A larger number of complete (centroperipheral) hard tissue barriers with predominance of dentinal tubules was observed to the ProRoot MTA when compared with the Ca(OH)2 group. [source] | |||||||||||||