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Biomedical subjects

L S Spångberg

Publications and source records attributed to L S Spångberg.

At least 19 recordsLinked to original sources
PubMed2001

Effects of enamel matrix derivative on gene expression of primary osteoblasts.

OBJECTIVE: The aim of this study was to investigate the effects of enamel matrix derivative (EMD) on gene expression of collagen alpha1 (I), osteocalcin, prostaglandin G/H synthase 2 (PGHS-2), interleukin-6, and insulin-like growth factor I in primary mouse osteoblasts. STUDY DESIGN: Primary osteoblasts were digested from 6- to 8-day-old mouse calvaria. Cells were divided into 4 groups and cultured for 24, 48, and 72 hours with a serum-free modified Eagle medium as negative control, modified Eagle medium with 25 microg/mL EMD, modified Eagle medium with 100 microg/mL EMD, and modified Eagle medium plus 10% fetal bovine serum as positive control. Gene expression was determined by Northern blot and reverse transcription polymerase chain reaction analysis. RESULT: EMD enhanced collagen I, interleukin-6, and PGHS-2 expression and did not stimulate the expression of osteocalcin and IGF-I. CONCLUSION: These results indicate that EMD might regulate certain gene expression during periodontal tissue regeneration.

Animals↗
PubMed2001

A prognostic model for assessment of the outcome of endodontic treatment: Effect of biologic and diagnostic variables.

OBJECTIVE: Many biological variables, endodontic treatment factors, and restorative considerations have been suggested in the literature to affect the outcome of endodontic treatment. However, few attempts have been made recently to study these variables further. The purpose of this study was to identify the biologic and endodontic treatment-associated variables that are most predictive of treatment outcome for conventional endodontic therapy and to determine the magnitude of risk these variables pose on the outcome. STUDY DESIGN: The population of this historical prospective cohort study comprised a total of 200 teeth with 441 root canals. Diagnostic and treatment information was abstracted from the original patient records. An endodontic follow-up examination was conducted 4 +/- 0.5 years after obturation. Each tooth/root was analyzed according to 3 indices of periradicular status at 2 time points. The main outcome measure was the presence of apical periodontitis. The criteria used for evaluation of the outcome were modified from Strindberg. Data were subjected to univariate and multivariate analysis. Logistic regression models were fit by using various clinical measures to determine which combination of biologic and treatment-associated factors best predicted treatment outcome. RESULTS: The preoperative pulp diagnosis, the periapical diagnosis, the preoperative periapical radiolucency size, and the sex of the patients were revealed, by means of univariate analysis, to exert a significant influence on endodontic treatment outcome (P <.05). In the logistic regression model, the strongest effect on postoperative healing was the presence and magnitude of preoperative apical periodontitis. In the presence of this variable, no other factor contributed value to the prediction. The correct prediction of this model was 74.7% (P <.05). CONCLUSION: The major biologic factors influencing the outcome of endodontic treatment appear to be the extent of microbiological insult to the pulp and periapical tissue, as reflected by the periapical diagnosis and the magnitude of periapical pathosis.

Acute Disease↗
PubMed2000

A comparison of stainless steel and nickel-titanium H-type instruments of identical design: torsional and bending tests.

OBJECTIVE: For a true comparison of clinically relevant qualities of instruments manufactured from different alloys, the instrument must be identical in design. The purpose of this study was to perform mechanical tests on stainless steel and nickel-titanium instruments of identical design. STUDY DESIGN: Identical experimental endodontic files of H-type with double helix were fabricated from stainless steel and nickel-titanium alloys. Torsional and bending tests were carried out according to American National Standards Institute/American Dental Association specification No. 58 and International Standards Organization No. 3630/1. Changes in instruments during the testing were also analyzed with scanning electron microscope technique. RESULTS: The results indicated that the torsional moment of the stainless steel files was significantly higher than for the nickel-titanium files (P <.001), whereas the mean angular deflection for the nickel-titanium files was significantly higher. The mean bending moment for the nickel-titanium files was significantly lower (P <.001) than the mean value for the stainless steel files. The scanning electron microscope demonstrated that the fracture surfaces of the stainless steel files were brittle, whereas the nickel-titanium files had a ductile fracture. CONCLUSIONS: When the design of endodontic instruments of different alloys is identical, the nickel-titanium files are more flexible in bending. However, nickel-titanium files require less force to deform to fracture.

Dental Alloys↗
PubMed1999

Antifungal effects of sodium hypochlorite and chlorhexidine in root canals.

The purpose of this study was to evaluate the antifungal properties of 0.12% chlorhexidine, 1% NaOCl, and 5% NaOCl. Root sections were enlarged and the smear layer was removed in half of the specimens. The specimens were fixed in the wells of tissue culture plates. Each root canal was dispensed with an inoculum of Candida albicans. After 10 days, the root sections were treated with 3 ml of either disinfectant solution for 1 min, 5 min, 30 min, and 1 h. Then, root sections were incubated in test tubes having Sabouraud's Dextrose Broth at 37 degrees C for 24 h. In the presence of the smear layer, antifungal activity was observed only in 1-h treatment groups for all solutions. However, in the absence of the smear layer, 5% NaOCl alone started to show antifungal activity after 30 min. The antimicrobial effectiveness of irrigating solutions should be re-evaluated, particularly in patients predisposed to oral candidiasis.

Anti-Infective Agents, Local↗
PubMed1999

Permeability changes of dentine treated with titanium tetrafluoride.

OBJECTIVES: The aim of this research was to evaluate the effect of titanium tetrafluoride on dentine permeability in comparison with sodium fluoride and acidulated phosphate fluoride to determine their contribution to acid resistance of dentine. METHODS: Thirty-two dentine discs were prepared from extracted mandibular molars. The hydraulic conductance of all discs was measured before and after the formation of smear layer. The discs were then randomly divided into five experimental and one-control groups. Coronal surfaces of dentine discs were treated with either fluoride solutions of NaF, APF, 1% TiF4, 0.5% TiF4 and 0.1% TiF4 or de-ionised water. Following the measurement of hydraulic conductance, treated surfaces were subjected to 25% citric acid application. Then, final permeability measurements were made. The data were statistically analysed using ANOVA and Tukey's HSD multiple comparisons. RESULTS: While smear layer formation considerably reduced dentinal permeability of dentine discs, fluoride or de-ionised water application to smeared surfaces did not cause any significant change in hydraulic conductance (p > 0.05). After citric acid application, control and NaF groups showed higher permeability values than 1%, 0.5% and 0.1% TiF4 and APF groups (p < 0.01). CONCLUSION: Clinical use of acidic solutions of titanium tetrafluoride in dentine cavities may be considered since smeared dentine surfaces are modified to a stabile and acid-resistant state.

Acidulated Phosphate Fluoride↗
PubMed1998

Integrin expression in human dental pulp cells and their role in cell attachment on extracellular matrix proteins.

Integrins are a family of heterodimeric glycoproteins consisting of alpha and beta subunits that noncovalently interact to form cell surface adhesion receptors. The objective of this study was to identify integrins in human dental pulp cells and determine their role in human dental pulp cell attachment to the biological active molecules, laminin and fibronectin. Integrin expression was studied by immunoblot and immunoprecipitation using monoclonal integrin antibodies. The role of integrin in human dental pulp cell adhesion on laminin and fibronectin was determined by inhibition of cell adhesion with those antibodies. This study found human dental pulp cells expressed alpha 1, alpha 3, alpha 5, alpha 6, alpha v, and beta 1 integrin subunits. The adhesion of human dental pulp cells to laminin and fibronectin was not inhibited by monoclonal antibody to any subunit, except that anti-beta 1 antibody inhibited pulp cells adhesion on laminin. These data provide information for further studying the role of integrins in dental pulp cell biological function.

Cell Adhesion↗
PubMed1998

Morphologic effects on L929 fibroblasts of titanium tetrafluoride application.

OBJECTIVE: The aim of this study was to investigate the effect of titanium tetrafluoride solution on L929 fibroblasts by scanning electron microscopy. Titanium tetrafluoride was then compared with sodium fluoride and acidulated phosphate fluoride. STUDY DESIGN: Cells were treated with fluoride solutions for 1 minute either directly, through a filter membrane with a pore size of 0.4-micron, or indirectly, through dentin disks; they were then investigated at an electron microscopic level. RESULTS: Fluoride application on smeared dentin disks showed fewer cytotoxic effects on fibroblasts than application on nonsmeared dentin disks. Acidulated phosphate fluoride and titanium tetrafluoride appeared to be more cytotoxic than sodium fluoride. Because all fluoride solutions used in this study contained the same fluoride concentration, pH was considered to be the main factor causing the higher toxicity. CONCLUSION: Because these solutions demonstrated toxicity in vitro, they must be further evaluated under in vivo conditions to ascertain their clinical safety.

Acidulated Phosphate Fluoride↗
PubMed1998

Contemporary endodontology.

Clinical endodontics has made significant progress during this century. This lecture will critically review the major breakthroughs that have taken place during this period. The final judgement of the value of this progress, however, is the quality of care we can deliver to our patients. Although the advances have been impressive, there are also major disappointments and problems that need to be recognised. Looking at clinical endodontics today, there is clearly a dissonance between sound scientific knowledge and empirical clinical practice. It is important that these problems are recognised and that endodontic research and teaching are refocused. Only by decisive action can progress be assured for clinical endodontics and the prospect will be bright.

Dental Pulp Diseases↗
PubMed1997

Colonization of Candida albicans on cleaned human dental hard tissues.

Candida albicans is a fungus that commonly infects oral mucosal surfaces. Limited data exist on biofilm formation by C. albicans on dental surfaces. Human premolar teeth were infected with C. albicans for 10 days and hard-tissue surfaces were examined with a scanning electron microscope. Enamel, cementum and dentine, in the absence or presence of a smear layer, were readily colonized by this micro-organism. Hyphae penetrated into cracks, followed the ridges of the cavities and migrated into dentinal tubules. Blastospores and hyphae were embedded in an extracellular material. These findings suggest that dental hard tissues may be invaded by C. albicans and thus can potentially present a reservoir for disseminating candidal infections.

Bicuspid↗
PubMed1997

Growth patterns of Candida albicans in relation to radicular dentin.

UNLABELLED: Candida albicans is the most common fungal pathogen isolated from the oral cavity. The role of this organism as an endodontic pathogen is poorly understood. OBJECTIVES: The aim of this study was to observe the interaction of C. albicans with root canal walls and the growth patterns of this microorganism in relation to radicular dentin. STUDY DESIGN: Fifteen root sections were infected with C. albicans grown in calf serum and incubated for various periods. The sections were fixed in glutaraldehyde, split into two halves, and evaluated by scanning electron microscopy. RESULTS: Blastospores and hyphal structures were observed on the root canal walls of all specimens. Filamentous hyphal form was dominant in 5-day specimens. Most of the hyphae and blastospores showed penetration into dentinal tubules. The body of germinating mother cells and hyphae demonstrated collapsed cell walls as a result of vacuole formation. CONCLUSIONS: With this invasive affinity to dentinal structures, C. albicans may be considered a dentinophilic microorganism.

Candida albicans↗
PubMed1996

Machining efficiency and wear resistance of nickel-titanium endodontic files.

OBJECTIVE: Nickel-titanium endodontic files are more flexible than stainless steel. Little information is reported concerning machining efficiency and wear resistance of nickel titanium. This study assessed the dentin-machining ability and wear resistance of nickel titanium endodontic files in vitro. STUDY DESIGN: The method described earlier to assess machining efficiency and wear resistance of stainless steel files was used. Eight different types and brands of nickel titanium files were studied: Ultra-Flex Hedström, Ultra-Flex K, Mity Hedstrom, Mity K, Mity Turbo, Hedstrom Naviflex NT, NiTiFlex, and Hyflex X-file. Thirty files of each brand were evaluated. One-way ANOVA and t tests were performed to analyze the data. RESULTS: Considerable variation was found in matching efficiency and wear. The best initial machining ability of all nickel titanium instruments was recorded for the Hyflex-X file (0.60 +/- 0.16 mm2); the poorest performance was for the Mity Turbo file, which machined less than one third of the best performing instrument (0.19 +/- 0.12 mm2). CONCLUSIONS: We compared our results with results of a previous study of stainless steel endodontic files and concluded that nickel titanium instruments are as aggressive as or better than stainless steel instruments in removing dentin. They are also more durable than their stainless steel counterparts.

Analysis of Variance↗
PubMed1995

The endodontic file is a disposable instrument.

Most cutting and machining tools wear when properly operated on intended substrates. Little is known about endodontic files when machining on human dentin. It was shown earlier that the efficiency of files was very variable when evaluated on Plexiglas substrates. The present study of seven different brands and types of files was undertaken to understand their wear better when machining human dentin. It was shown that all files evaluated rapidly deteriorated when machining dentin. This decline in efficiency was significant but different within, as well as, among brands. It was suggested that endodontic files be disposable.

Dentin↗
PubMed1995

The prevalence and technical quality of endodontic treatment in an American subpopulation.

Few data have been collected regarding the prevalence and quality of root canal therapy in American populations. European studies of various populations were used as a model for the evaluation of the prevalence and technical standard of endodontic treatment in a patient group seen for screening at a United States dental school. Full-mouth radiographic series were examined for the presence of root fillings, periapical pathologic conditions, and coronal restorative status. The obturation density and length were also recorded. Of 5272 teeth examined, 5.5% had root fillings. Periapical disease was evident in 4.1% of all teeth and 31.3% of root-filled teeth. Lesser-quality root fillings were more strongly associated with periapical disease than were higher-quality obturations. In addition, only 42% of the obturations could be considered technically satisfactory. Such data suggests that more research must be directed toward the study of factors that affect treatment outcome.

Adult↗
PubMed1995

Effect of reduced air pressure on dye penetration in standardized voids.

OBJECTIVE: This study determined the correlation between the degree of dye penetration in standardized voids to various reduced pressures. STUDY DESIGN: Standardized voids of 0.50 and 0.22 mm in diameter were created in 60 human roots; specimens were divided into five groups. Four groups were subjected to a 2% filtered aqueous methylene blue dye solution under different conditions of atmospheric pressure for 7 days and reduced pressures of a 10 torr, a 260 torr, and a 510 torr for 30 minutes. The conditions for the fifth group were similar to the last group except that ethyl alcohol was substituted for water in the dye. RESULTS: All positive control specimens showed complete dye penetration. The least linear dye penetration was observed in passively immersed specimens. The results were significantly different from those when reduced pressure had been used (p < 0.001). There were no significant differences among the groups with reduced pressure. No significant difference was found at any pressure level between the means of dye diffusion in the 0.50 and the 0.22 mm voids. The smallest standard deviations were observed for the most reduced air pressure of 10 torr, followed by the group of the least reduced pressure of 510 torr, with the use of the tincture dye solution. CONCLUSIONS: A 10-torr reduced pressure and an application of the tincture dye solution would provide an improved method for microleakage studies.

Air Pressure↗
PubMed1994

Assessment of marginal stability and permeability of an interim restorative endodontic material.

The purpose of this study was to assess the marginal stability and permeability of a new interim restorative endodontic material, Tempit (Centrix Inc., Milford, Conn.), and to compare the findings with the results of two commonly used restorative endodontic materials, Cavit (Premier Dental Products Co., Philadelphia, Pa.) and IRM (Intermediate Restorative Material Capsules, The Caulk Co., Division of Dentsply International Inc., Milford, Del.) This study was performed in several steps. First, the endodontic access cavities were prepared and restored on 80 extracted mandibular molars. The samples were exposed to methylene blue dye solution for 6 days, thermocycled, and sectioned; the dye penetration and diffusion were measured along the margins and into the body of the materials. The second experiment was a special study performed in standardized glass tubes to better evaluate the marginal and body dye penetration into the materials by increasing the length of the fillings. To eliminate the possibility of hygroscopic setting mechanisms of materials, samples were first allowed to set under water before dye was introduced. Cavit and Tempit showed a substantial amount of dye diffusion into the body of the materials. Cavit exhibited the best sealing ability at all times. The marginal and body dye penetration were significantly different for the Tempit material in all experiments than Cavit (p < 0.001). IRM demonstrated the least body penetration of all three materials (p < 0.001) but had a substantial marginal leakage not significantly different from the results of the Tempit material (p = 0.6 and p = 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Cytotoxic effects of gutta-percha solvents.

Cytotoxicity of commonly used gutta-percha solvents was evaluated. Gutta-percha dissolved by chloroform, halothane, or turpentine was evaluated with the radiochromium release method using L929 mouse fibroblast cells. All solvents were toxic. Turpentine was most toxic followed by halothane and chloroform, which caused similar levels of cell injury.

Animals↗