ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01352.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe purpose of this study was to investigate the penetration of smeared and nonsmeared dentine byStreptococcus gordonii.Prepared human roots, grouped as either nonsmeared or smeared, were immersed in a suspension ofS. gordoniicells for 3 weeks. The roots were then prepared for scanning electron microscopy and histological analysis. Dentine discs prepared from coronal dentine were grouped similarly. Using a fluid filtration apparatus, the hydraulic conductance (Lp) of each disc was determined before and after incubation with bacterial suspension. Scanning electron microscopy evaluation of the roots following infection with bacteria showed no change in the smear layer (P<0.0001). Histological sections revealed that bacterial penetration of all the nonsmeared samples had occurred, while nine out of 10 smeared samples showed no bacterial penetration (P<0.0001). The Lp of the nonsmeared discs was significantly reduced by 42% (P0.05). The results suggest that dentinal smear layers are an effective barrier to dentinal tubule invasion byS. gordonii.

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01353.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe permeability, temperature and morphologic changes of the wall of the root canal induced by Nd:YAG, CO2and argon lasers were studied. The changes were evaluated according to the presence or absence of a smear layer. Root canals of 140 human single‐rooted teeth were enlarged using a step‐back technique. Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. Temperature changes were measured using a thermovision system, and morphological changes were evaluated by scanning electron microscopy. Laser energy was delivered into the canal by means of a flexible optical fibre or metal tip. There were statistically significant differences in permeability between Iased groups with and without a smear layer in the cervical third of the root canal following lasing. In the middle third of the root canal, all three laser types induced permeability increases in groups with a smear layer. In the apical third, statistically significantly decreases in permeability were observed among C02 laser and Nd:YAG compared with control group (P<0.01). Rises in temperature ranged from a minimum of +10.1 °C (CO2laser) to a maximum of +54.8 °C (argon laser). All three laser devices appeared capable of producing a glazed‐like surface and

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01354.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryAn in vitro study of a possible correlation between penetration of dentinal tubules by four root canal sealers and microleakage of external fluids into the canal was done using a dye leakage method and scanning electron microscopy. The root canals of 45 teeth were instrumented and the smear layer removed prior to obturation of root canals with gutta‐percha and one of four sealers: Diaket, Endomethasone, CRCS or Ketac‐Endo. The extent of leakage was scored after immersion in India ink for 72 h. The same specimens were also used for scanning electron microscopic evaluation. There was a statistical difference in leakage patterns between the groups (P<0.05). Diaket had lower microleakage scores than the other sealers (P<0.05). When the scores for penetration of sealers into the tubules were analysed, Ketac‐Endo demonstrated the least penetration (P<0.01). There appeared to be a converse relation between tubular penetration and dye leakage, but the correlation was not statistically significant (P<

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01355.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe prime objective of this study was to develop and test a method of modelling the dental root canal system using a vinyl resin, type UCAR‐VYHD. It also aimed to verify if the resin models allow a three‐dimensional evaluation of those features of the pulpal morphology of human permanent mandibular incisor teeth, which might be associated with periodontal disease. One hundred and eleven freshly extracted teeth were studied. Pre‐extraction clinical records and periapical radiographs were used to deduce the presence or absence of periodontal disease. Each extracted tooth was radiographed in two perpendicular planes before being opened by conventional orthograde endodontic technique, and photographed in a scanning electron microscope. The patent pulp space was then obturated with the vinyl resin. Scanning electron photomicrographs of the resin replicas and of the teeth were compared with the earlier radiographic images to correlate the morphological findings. The numbers of root canals and apical foramina were recorded. This study showed that in mandibular incisors with periodontal disease there was a relatively low incidence of lateral canals (7.2%). The modelling technique was found to be reliable, reproducible, and provided sufficient detail to allow three‐dimensional analysis of root canal mor

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01356.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryThe effects of varying clinically relevant patterns of anaesthetic‐vasoconstrictor combinations used for peri‐radicular surgery on plasma concentrations of catecholamines and haemodynamic responses was studied in the canine model. Five mongrel dogs were anaesthetized with sodium pentobarbital. A femoral canula was inserted to measure central blood pressure and an ECG was used to monitor heart rate and any associated arrhythmias. Femoral venous blood samples were drawn before initial injection and at 3 and 10 min after injections. Plasma catecholamine concentrations were determined using high pressure liquid chromatography (HPLC). Injection protocols used three time periods, 30, 60 and 90s, with solutions containing 1:100000 and 1:50000 adrenaline. No significant changes in heart rates or presence of arrythymias were noted over the experimental protocol. Catecholamine levels in pico moles mL‐1were within the normal range at the 3‐min sample level. At the 10‐min sample time there was a more erratic range of concentrations, with most samples within the normal range. This may have been due to endogenous release of catecholamines in specific animals. The data identified trends in both the haemodynamic parameters and plasma catecholamine levels that can legitimately support the careful use of higher levels of a vasoconstrictor when patient profiles and surgical need

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01357.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01358.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0143-2885    

DOI:10.1111/j.1365-2591.1996.tb01359.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY