摘要:

Abstract—The aim was to study effects of the size and form of the occlusal part of Class II cavities on elastic outward bending during loading of buccal and lingual walls, separated by the preparation. Twenty newly extracted caries‐free premolars were used. A special arrangement for standardized cavity preparation was set up. In order to obtain accurate measurements of the outward bending of loaded cavity walls, an electronic tensile test device was constructed. Methodologic studies showed an insignificant departure from linearity between outward bending and load. All deformation was elastic. Correction factors were determined for strain of the apparatus as well as for indentation in the tooth substance. Measurement accuracy was calculated to ±0.12 N for force and ±0.2 μm for movement. In accordance with statistical principles, a few outlying measurements were discarded. The outward bending of buccal and lingual walls of cavities suitable for conservative restoration with dental amalgam was about 0.15 μm per Newton. Outward bending increased dramatically with exaggerated cavity depth and width. In the light of present knowledge of average chewing forces and tooth contacts in the habitual intercuspal position in young dentate adults, there seems to be little risk of leakage between conservative restorations and cavity walls as a result of elastic outward bending, though the risk certainly does increase with the depth and width of the

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01015.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Intraindividual variations in the mutans streptococci measured by Strip mutans, in a 1‐day and a 5‐day period, as well as the effect of toothbrushing, were investigated. 30 subjects participated, and their levels of salivary mutans were estimated by a scale containing four steps. With the exception of three comparisons, time intervals of different lengths did not cause a deviation of more than one step. Comparisons made before and after toothbrushing yielded the same score in 22 cases, whereas two subjects showed a discrepancy of two steps. Clearly, in a short‐term perspective, variations can certainly be found, but more pronounced discrepancies a

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01016.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—The quantity ofS. mutans, total streptococci, and lactobacilli on sound enamel surfaces and 1‐yr‐old glass ionomer cement and composite resin fillings with the cervical margins placed subgingivally was compared intraindividually. The amount of bacteria was compared to their number in saliva. The evaluation was done in a cross sectional study, where the patients continued to use their customary oral hygiene procedures and during a 14‐day period of experimental plaque formation. The number of lactobacilli andS. mutansrecovered from the test surfaces indicated that the critical salivary concentrations necessary for the isolation ofS. mutansand lactobacilli from glass ionomer cement and composite resin surfaces are the same as for the enamel surfaces. The fluoride levels in plaque adjacent to glass ionomer cement will not become high enough to inhibit the accumulation of the investigated b

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01017.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—A 65‐kilodalton protein was identified in the outer membrane ofFusobacterium nucleatumFevl by SDS‐PAGE. The relative amount of the protein varied during growth, being greatest in stationary phase. The protein was radio‐labeled by [125I]‐lactoperoxidase treatment of live cells and was only partially cxtractable with 2% sodium dodecylsulfatc (SDS) at room temperature, and therefore assumed to be both exposed to the cell surface and peptidoglycan associated. In intact cells the protein bound diisopropylfluorophosphate (DFP), indicating that it may be a serine protease. DFP‐binding activity depended apparently on proper localization of the proteins in the membrane. Several methods were tried in attempts to purify the 65‐kilodalton protein; the method that gave best results was preparative SDS‐polyacrylamide gel electrophoresis. The isoelectric point was determined to about pH 5. Amino acid composition analysis showed that the 65‐kilodalton protein possesses an excess of hydrophilic over hydrophobic residues, polarity index 52%. TheN‐terminal end of the protein was

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01018.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—The aim was to evaluate chemically modified starches (CMS) from a cariologic point of view as alternatives to gum arabic in sugar‐free lozenges. Two commercial CMS, Purity Gum 40 and Capsul, were selected due to their comparatively low availability to alpha‐amylase in vitro. Both gelatinized CMS suspensions and lozenges were tested in vivo by measuring plaque pH. The results showed that suspensions of Purity Gum 40 or Capsul were less available to alpha‐amylase in vitro than the soluble starch reference. However, the initial phase of amylolysis was comparatively rapid also with CMS. In spite of the slower rate of hydrolysis, suspensions of the two CMS reduced pH of dental plaque in vivo to the same extent as soluble starch, but somewhat less compared with glucose. Lozenges with Purity Gum 40 also lowered plaque pH, although less than when administered as a precooked suspension. The most prominent pH drop was found with a lozenge containing Purity Gum 40‐sucrosc‐glucose, while tablets with gum arabic‐maltitol and pectin‐gelatine‐Lycasin somewhat increased the pH values. To conclude, it is not recommended to exchange gum arabic for CMS in sugar‐free lozenges, since the cariogenic properties of the products are

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01019.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Crevicular fluid (CF) samples were collected by paper strips from healthy and diseased sites. The molecular distribution of fibrin and fibronectin in CF and plasma samples was investigated using SDS‐polyacrylamide gel electrophoresis and specific immunoglobulins. Intact fibrin was found in all CF samples. In addition several bands with both lower and higher molecular weights than intact fibrin were seen. These bands were not present in the plasma samples. The low molecular weight bands are suggested to represent degradation products of fibrin. The high molecular bands could be fibrin‐fibronectin complexes or fragments of large fibrin polymers. Fibronectin degradation products, but not intact fibronectin, were seen in both healthy and diseased sa

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01020.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—The effect of growth hormone (GH) treatment on craniofacial development was studied in five children exhibiting growth retardation following bone marrow transplantation. Linear and angular measurements were made on lateral radiographic cephalograms taken prior to the start of GH treatment and after an average treatment time of 1.2 yr. The results showed that the mean growth increments of mandibular length in the GH treated children, exceeded the corresponding values of the control group by 150% during the period of investigation. It is suggested that this dimensional increase in the patients was due to GH stimulation on the chondral growth process in the mandibular condyle

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01021.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Correlations between craniomandibular disorders (CMD) symptoms and an inherited factor (general joint hypermobility) were studied in 193 adolescents (96 girls and 97 boys). They answered a questionnaire concerning CMD symptoms, oral parafunctions, head and jaw trauma and symptoms from other joints. Joint mobility was assessed by determining the Beighton score (0‐9). Twenty‐eight percent of the girls and 21% of the boys could perform four or more of the maneuvres. Twenty‐two percent of the girls and 3% of the boys were extremely hypermobile (score ≥5). Eighty‐nine percent were aware of some oral parafunction and the prevalences of oral habits were about the same in the two groups. Girls reported significantly more dysfunction symptoms than boys. No indication was found that oral parafunctions generally produced CMD but a systemic factor (joint hypermobility) seemed to play an important role when the masticatory system was exposed to local forces as in oral parafunction. This may be one explanation for the predominance of females among C

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01022.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—A comparison of the effect on mold filling of using vacuum vs. a protective gas of Ar during casting has been carried Out. A conventional gold casting alloy and a NiCr‐alloy without Be have been cast at three temperatures into two different mold patterns: a mesh screen and a cylindrical crown with a 30° sharp margin. In all cases the application of vacuum rather than a protective gas of Ar was found to be beneficial for the mold filling. A reduction of the back pressure due to the trapped gases in the last part of the mold to be filled with metal was assumed to be the major reason for this effect. A reduced surface tension of the melt may also contribute. An improved mold filling was also observed for both nets and crown margins with increasing supertemperature of the melt. Physical reasons for this effect have been sugge

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01023.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Fluoride availability from two glass‐ionomer luting agents, Ketac‐Cement and Aqua‐Cement, was monitored after a l‐h treatment in distilled water at pH 7. The recorded results were then compared to the ones obtained from those same cements, after l h, in saliva, in water pretreated with saliva (pH 7 and 4.5), and in albumen and phosphate buffer solutions (pH 7). The Mann‐Whitney two‐sample rank test was utilized in order to identify the differences. The presence of proteins and phosphate reduced fluoride availability. A reduction in the pH from 7 to 4.5 resulted in an increased rate of fluoride release, in water, from glass‐ionomers pretreated with saliva. The present study indicates that fluoride availability from glass‐ionomers, in vivo, is pH controlled. The rate controlling factors appear to be phosp

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01024.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY