Showing papers in "Journal of Dental Research in 1975"
TL;DR: A longitudinal study was performed to assess the effects of radiation-induced xerostomia on the human oral microflora and pronounced microbial population shifts were found in each of five intraoral sites tested.
Abstract: A longitudinal study was performed to assess the effects of radiation-induced xerostomia on the human oral microflora. Pronounced microbial population shifts were found in each of five intraoral sites tested. Cariogenic microorganisms gained prominence at the expense of noncariogenic microorganisms in concert with the saliva shutdown. These changes occurred before the onset of clinical caries irrespective of whether or not a topical fluoride gel was used as a caries preventive.
276 citations
TL;DR: The interaction of chlorhexidine with carboxyl, sulfate, and phosphate groups was studied in vitro, including factors that might interfere with these interactions, and the properties of cetylpyridine in the same systems also were investigated for comparison.
Abstract: The marked plaque-inhibiting activity shown by chlorhexidine1 is a unique property demonstrated only by the bis-biguanides.2,3 Initial killing of the bacteria by the chlorhexidine mouthrinse seems not to be the decisive factor in the plaque inhibition, as antibacterial agents with as high or higher activity against salivary bacteria did not show corresponding clinical effects.2 Considerable evidence has been accumulated indicating that a retention of bisbiguanides in the mouth is the basis for the plaque inhibition.4-9 About 30% of the chlorhexidine introduced into the mouth during a mouth rinse is retained.9,10 The teeth are not a major retention site, at least not quantitatively, but plaque-covered teeth have been shown to bind limited quantities of the drug.\"1 Results of studies that used mouthrinses at different pH levels strongly indicated that acidic groups, presumably on the macromolecules of the mucous secretions covering the oral surfaces, are the receptors responsible for the major share of the retained chlorhexidine. Electrostatic binding between the acidic protein groups and the basic bis-biguanide molecules seems to be the mechanism involved (Fig 1) .7,8,10 In the current study, the interaction of chlorhexidine with carboxyl, sulfate, and phosphate groups was studied in vitro, including factors that might interfere with these interactions. The properties of cetylpyridine in the same systems also were investigated for comparison, as this is a basic antibacterial agent with virtually no plaqueinhibiting effect.2 It was believed that such data could supply information that might shed light on the mechanism of adsorption and release of chlorhexidine in the mouth and possibly indicate the properties essential for a substance to be retained onto and released from the oral surfaces. Such substances may be of interest not only in dental research, but could possibly also serve as carriers for other drugs when a gradual, slow oral release is needed. The chlorhexidine-binding properties of protein extracts from the major salivary glands at different pH levels were also investigated.
249 citations
TL;DR: The mechanical behavior ("shape memory") associated with martensitic solid-state transformation in nearly equiatomic Ni-Ti alloy (55-Nitinol) has been studied.
Abstract: The mechanical behavior ("shape memory") associated with martensitic solid-state transformation in nearly equiatomic Ni-Ti alloy (55-Nitinol) has been studied. Potential dental and medical applications for 55-Nitinol (55% Ni, 1.5% Co, balance Ti, by weight) and for 60-Nitinol (60% Ni, by weight) have been suggested.
156 citations
TL;DR: Gutta-percha endodontic filling points were found to obey Hooke's law and displayed a prominent upper and lower yield point when stressed beyond the proportional limit.
Abstract: Gutta-percha endodontic filling points were found to contain approximately 20% gutta-percha (matrix), 66% zinc oxide (filler), 11% heavy metal sulfates (radiopacifier), and 3% waxes and/or resins (plasticizer). The mechanical properties were indicative of a partially crystalline viscoelastic polymeric material. They were found to obey Hooke's law and displayed a prominent upper and lower yield point when stressed beyond the proportional limit. The essential differences in mechanical properties of individual brands were found to be a function of the gutta-percha and zinc oxide concentration.
147 citations
TL;DR: Sixteen inner city children attending a pedodontic clinic were shown either a filmed demonstration of a child model cooperatively undergoing dental treatment or a film unrelated to dental activity.
Abstract: Sixteen inner city children attending a pedodontic clinic were shown either a filmed demonstration of a child model cooperatively undergoing dental treatment or a film unrelated to dental activity. The group viewing the modeling film showed significantly fewer disruptive behaviors during restorative care and were rated as less fearful than the control group.
136 citations
TL;DR: Two layers of carious dentin from extracted human teeth were observed with an electron microscope and showed expanded odontoblastic processes, sound collagen fibers, and apatite crystcls bound to the fibers like fringes.
Abstract: Two layers of carious dentin from extracted human teeth were observed with an electron microscope. The first layer, which is superficial and fuchsin-stainable, showed degenerated collagen fibers and granular or leaflike inorganic crystals irregularly scattered. The second layer, which is profound and fuchsinunstainable, showed expanded odontoblastic processes, sound collagen fibers, and apatite crystals bound to the fibers like fringes.
129 citations
TL;DR: Lipoteichoic acid was compared with a preparation free of fatty acids to determine whether LPS-stimulated bone resorption is mediated by prostaglandin synthesis in bone and to obtain information on the portion of the endotoxin and lipote Jerichoic acid molecules necessary for their bone Resorptive effect.
Abstract: Endotoxins are lipopolysaccharides (LPS) contained in the cell walls of many gramnegative organisms such as Fusobacterium, Veillonella, Leptotrichia, and Bacteroides, which are bacterial types found in human dental plaque.' Lipoteichoic acids (LTA) are polymeric substances containing either glycerol or ribitol, phosphate, carbohydrate, and fatty acids, which are cell wall components of many gram-positive organisms in plaque.2 Endotoxins3 and lipoteichoic acids4 have been shown to have a wide range of biological effects. Previously obtained results indicate that endotoxins have the ability to stimulate osteoclastic bone resorption5 in tissue culture. The aims of this study were: to test the effects of lipoteichoic acid on bone resorption in tissue culture and to obtain information on the portion of the endotoxin and lipoteichoic acid molecules necessary for their bone resorptive effect. The following endotoxins from Salmonella minnesota6 (Fig 1) were compared: endotoxin from the smooth form which consists of the 0-specific polysaccharide, the polysaccharide core, and lipid A; endotoxin from the mutant form, R-345, which is lacking the 0-specific polysaccharide but contains most of the polysaccharide core and lipid A; endotoxin from the mutant form, R-595, which contains only 2 keto-3 deoxyoctonate KDO plus lipid A, and isolated lipid A. Lipoteichoic acid was compared with a preparation free of fatty acids to determine whether LPS-stimulated bone resorption is mediated by prostaglandin synthesis in bone.
112 citations
TL;DR: Solubility of human dental enamel in H3PO4 was studied in the pH range of 4.5 to 7.6 and the ion activity product, (Ca2+)5(PO4 3-)3 (OH-), for hydroxyapatite varied depending on the cumulative amount of the dissolution in a series of repetitive sequences of solubility experiments.
Abstract: Solubility of human dental enamel in H3PO4 was studied in the pH range of 4.5 to 7.6. Thermodynamic solubility of the enamel mineral was calculated in terms of the ion activity product, (Ca2+)5(PO4 3-)3 (OH-), for hydroxyapatite. The solubility product varied from 7.2 × 10-53 to 6.4 × 10-58 mol9 liter-9 depending on the cumulative amount of the dissolution of the solid in a series of repetitive sequences of solubility experiments.
111 citations
TL;DR: Microducers and modified cephalometric roentgenogram techniques were used to study maximum biting forces and moments in an adult male and found that the force at the second molar was approximately 10% greater than that at the first molar.
Abstract: Microducers and modified cephalometric roentgenogram techniques were used to study maximum biting forces and moments in an adult male. The force at the second molar was approximately 10% greater than that at the first molar. At the second molar, the moment of force was approximately 15% less than its value at the first molar.
108 citations
TL;DR: Analytical analyses show that the coefficients of the sixth degree polynomial equations appear to have potential as clinical indicators of arch form and, perhaps, malocclusion in children with "normal" occlusion.
Abstract: Polynomial and catenary equations were fit by least square error methods to the dentitions of seven children with "normal" occlusion. Mean and mean square error were then used to analyze accuracy of curve fits and asymmetries of arches. A lack of congruency for the "lines of occlusion" common to the maxilla and mandible suggest that the defining anatomic landmarks are inaccurate. These analyses show that the coefficients of the sixth degree polynomial equations appear to have potential as clinical indicators of arch form and, perhaps, malocclusion.
100 citations
TL;DR: Sucrose-rich diets had no demonstrable effects on total plaque accumulation, whereas total viable microbial density, Streptococcus mutans, and the lactobacilli populations increased, and in individual subjects, an inverse relationship between the S sanguis and S mutans population was observed.
Abstract: The effects of dietary sucrose levels on the microbial composition of 4- and 12-day plaque were investigated in eight dental students. Sucrose-rich diets had no demonstrable effects on total plaque accumulation, whereas total viable microbial density, Streptococcus mutans, and the lactobacilli populations increased. The S sanguis population was unaffected. However, in individual subjects, an inverse relationship between the S sanguis and S mutans population was observed.
TL;DR: In vitro corrosion of fresh amalgam resulted in the buildup of similar products as in vivo, and the corrosion products in an old amalgam were probably a mixture of tin-oxide and tin oxychloride.
Abstract: Corrosion products of amalgam produced in Ringer's solution were compared with products formed in vivo using scanning electron microscopy, X-ray microanalysis, and Potentiostatic anodic polarization. The corrosion products in an old amalgam were probably a mixture of tin-oxide and tin oxychloride. In vitro corrosion of fresh amalgam resulted in the buildup of similar products.
TL;DR: Growth inhibition of the indicator strains around the inoculum of stab culture of some S mutans strains was demonstrated and many gram-positive bacteria, including mycobacteria and streptomycetes, were sensitive to the antibacterial activity.
Abstract: Streptococcus mutans strains were surveyed to determine their lysogenicity. Growth inhibition of the indicator strains around the inoculum of stab culture of some S mutans strains was demonstrated. Many gram-positive bacteria, including mycobacteria and streptomycetes, were sensitive to the antibacterial activity.
Journal Article•
TL;DR: A quantitative microprobe analysis was conducted on three commercial amalgams to determine the nature of the phases present and the presence of tin in the Ag-Hg phase (gamma1) was confirmed and Cu-3Sn was found in the original alloy particles.
Abstract: A quantitative microprobe analysis was conducted on three commercial amalgams to determine the nature of the phases present. The presence of tin in the Ag-Hg phase (gamma1) was confirmed and Cu-3Sn was found in the original alloy particles. In the dispersant amalgam studied, little Sn-Hg phase (gamma-2) was found and the reaction phase Cu-6Sn-5 was identified.
TL;DR: Penetration of a liquid adhesive into human artificial and natural white spots, both acid-conditioned and nonconditioned, was studied and all artificial white spots showed penetration of the adhesive.
Abstract: Penetration of a liquid adhesive into human artificial and natural white spots, both acid-conditioned and nonconditioned, was studied. All artificial white spots showed penetration of the adhesive. Acid-conditioned natural lesions exhibited penetration to a lesser amount than in vitro lesions. Penetration in nonconditioned natural lesions was not apparent.
TL;DR: Substantial etching of enamel resulted with use of 50% H3PO4 with 2% NaF, and high fluoride incorporation in the surface provided additional protection of the conditioned enamel.
Abstract: The etching effect of 50% H3PO4 applied together with 2% NaF or SnF2 was compared with the effect of H3PO4 on pre- and postfluoridated enamel by scanning electron microscopy. Substantial etching of enamel resulted with use of 50% H3PO4 with 2% NaF. High fluoride incorporation in the surface provided additional protection of the conditioned enamel.
TL;DR: A two-body, wear-testing method was developed and the test results were used for comparing and ranking the rate of wear for an amalgam, an experimental composite resin, and a commercial composite resin.
Abstract: A two-body, wear-testing method was developed and the test results were used for comparing and ranking the rate of wear for an amalgam, an experimental composite resin, and a commercial composite resin. The ranking of wear found by this method was the same as that shown by clinical research for the rate of wear of amalgam and commercial composite resin.
TL;DR: The amount of enamel destroyed by salivary fermentation of snack foods and confections was not dependent on their sugar content; starch, flavoring agents, and other components also played a part.
Abstract: The amount of enamel destroyed by salivary fermentation of snack foods and confections was not dependent on their sugar content; starch, flavoring agents, and other components also played a part. Most enamel destruction was produced by fruit-flavored candies in which the inherent acid or high sugar concentration or both inhibited bacterial fermentation.
TL;DR: Although the oral cavity and dental arches of the Australian aborigine are large, studies of lingual and labial pressures indicate that the tongue is neither unusually large nor strong, which is probably the significant determinant of dental arch dimensions.
Abstract: Although the oral cavity and dental arches of the Australian aborigine are large, studies of lingual and labial pressures indicate that the tongue is neither unusually large nor strong. The Australian aborigine's pharyngeal cavity is smaller in height and depth than that of the American; just the opposite is true for the oral cavity. To the extent that environmental factors are important at all, the resting pressure of the lips, not tongue pressure during swallowing, is probably the significant determinant of dental arch dimensions.
TL;DR: The maximum tensile stresses and deftections in the amalgam restoration increased at least threefold with a zinc oxideeugenol base as compared with a ZnPO 4 cement base.
Abstract: A computerized dental model was used to study the stress induced in a Class 1 amalgam restoration when supported by bases of varying materials and thickness Under the same load, the maximum tensile stresses and deflections in the amalgam restoration increased at least threefold with a zinc oxide-eugenol base as compared with a ZnPO4 cement base
TL;DR: A high prevalence of hypodontia was detected among 820 first degree relatives of 305 probands and there was an increased risk if a second family member was affected, suggesting a polygenic mode of inheritance.
Abstract: A high prevalence of hypodontia was detected among 820 first degree relatives of 305 probands and there was an increased risk if a second family member was affected. Hypodontia is a common trait in the population, and a deviation from normal sex ratio was observed in those affected. These results suggest a polygenic mode of inheritance.
TL;DR: The amount of alveolar bone lost as a result of marginal periodontitis was increased by the addition of repeated mesiodistal jiggling of the teeth, which could represent an irreversible "co-destructive" effect or could merely be a functional adaptation of the periodontium.
Abstract: When repetitive mechanical injury was produced in combination with marginal periodontitis a significant loss of connective tissue attachment did not occur as compared with specimens in which periodontitis alone was produced. It seems unlikely, therefore, that there is a "co-destructive" factor effect on the loss of connective tissue attachment. The amount of alveolar bone lost as a result of marginal periodontitis was increased by the addition of repeated mesiodistal jiggling of the teeth. This could represent an irreversible "co-destructive" effect or could merely be a functional adaptation of the periodontium.
TL;DR: Replicas of a dentate human mandible were prepared in photoelastic resin material, representing the principal muscles of mastication, and the stresses generated within the models were examined by three-dimensionalphotoelastic stress analysis.
Abstract: Replicas of a dentate human mandible were prepared in photoelastic resin material. They were positioned in a supporting frame by means of struts, representing the principal muscles of mastication. Occlusal loading was simulated, and the stresses generated within the models were examined by three-dimensional photoelastic stress analysis.
TL;DR: The interruption of circulation through the inferior alveolar artery was followed by the establishment of a fast retrograde blood flow through the vessel, where the mental artery and the mandibular branch of the sublingual artery were the main vessels to contribute to that flow.
Abstract: The interruption of circulation through the inferior alveolar artery was followed by the establishment of a fast retrograde blood flow through the vessel. The mental artery and the mandibular branch of the sublingual artery were the main vessels to contribute to that flow. No histopathologic changes were found in the experimental hemimandibles; however, temporary regressive changes were found in the dental pulps of molars.
TL;DR: The frequency of occurrence of thick-curved maxillary central incisors, incisal fissures, and missing teeth were significantly different among the three groups.
Abstract: The incidence and types of dental trait anomalies found in individuals with cleft lip or cleft palate or both (cleft group), in siblings of the cleft group, and in a group of individuals without cleft lip or cleft palate (noncleft group) were compared. The cleft group had 1.02 anomalies per individual, the sibling group, 0.38; and the noncleft group, 0.17. The frequency of occurrence of thick-curved maxillary central incisors, incisal fissures, and missing teeth were significantly different among the three groups.
Journal Article•
TL;DR: Gas chromatography and a flame photometric detection system measured directly from mouth air the sulfur volatiles associated with malodor and the method appears potentially useful in objective clinical evaluation of mouth odor.
Abstract: Gas chromatography and a flame photometric detection system measured directly from mouth air the sulfur volatiles associated with malodor. Statistically significant reductions in the hydrogen sulfide and methyl mercaptan levels were observed with use of the test rinse vs a placebo rinse. The method appears potentially useful in objective clinical evaluation of mouth odor.
TL;DR: The purpose of this investigation was to determine the effects of tongue brushing on the "coating" formed on the dorsum of the tongue and what effect this procedure had on the inhibition of dental plaque formation in vivo.
Abstract: Brushing of the dorsum of the tongue has been reported to reduce the number of microorganisms on that organ (GILMORE and BHASKAR, J South Calif Dent Assoc 39: 893, 1971) , the plaque formed in vitro (GILMORE and BHASKAR, J Periodontol 43: 418, 1972), the chemotactic activity of saliva (WRIGHT and TEMPLE, J Periodontol 45: 134, 1974), and clinical plaque formation (JACOBSON, CRAWFORD, and McFALL, JADA 87: 134, 1973) . The purpose of this investigation was to determine the effects of tongue brushing on the \"coating\" formed on the dorsum of the tongue and what effect this procedure had on the inhibition of dental plaque formation in vivo. Two studies were conducted. In the pilot study, 46 enlisted military men, ranging in age from 17 to 23 years, served as participants. Each man received two identical examinations to determine both the amounts of coating on the dorsum of the tongue and of supragingival plaque. The initial examinations were conducted on day 0 and the final examinations six weeks later. An index was specially devised to evaluate tongue coating. The scores were as follows: 0, no coating; 1, slight coating; 2, moderate coating; 3, heavy coating. The plaque accumulations were scored using the index devised by Quigley and Hein (JADA 65: 2, 1962). Immediately after their initial examinations, the men received complete scalings and prophylaxes. On the basis of the initial plaque examination, the men were separated into two groups in such a manner that the mean plaque scores of the groups were the same. The men in group 1 were
TL;DR: Plastic brackets were bonded to 560 extracted human teeth with use of two orthodontic adhesive systems that were adequately strong to withstand routine orthodentic and estimated masticatory forces.
Abstract: Plastic brackets were bonded to 560 extracted human teeth with use of two orthodontic adhesive systems: (1) methyl methacrylate resin bonded to a sealant that was polymerized using ultraviolet light, and (2) self-polymerizing methyl methacrylate resin bonded directly to the etched enamel. Tensile and shearlike tests were performed. Prolonged exposure to heat, moisture, and severe temperature changes decreased the shearlike strength of both adhesives. Both systems were adequately strong to withstand routine orthodontic and estimated masticatory forces.
Journal Article•
TL;DR: An idealized porcelain jacket and porcelains-fused-to-metal crown model was prepared, loaded, and analyzed to establish the trends and distributions of the internal and external stresses.
Abstract: An idealized porcelain jacket and porcelain-fused-to-metal crown model was prepared, loaded, and analyzed to establish the trends and distributions of the internal and external stresses. Loads at 30 degrees to the vertical axis created adverse tensile stresses at the level of the gingiva and specifically at the gold-dentin-cement interface.
TL;DR: The nature and function of the mucus barrier is studied, including a fluorescent microscopy study of the passage of fluorescent dyes into the epithelium in vivo, including the effect of saliva on this passage.
Abstract: MacPhee and Cowley' state that the \"mucous membrane of the mouth is covered by a layer of saliva which acts as a primary barrier to the spread of infection\"; they call this the \"mucus barrier.\" In the present paper the nature and function of the mucus barrier is studied. The first part is a report of the ultrastructure of this barrier; the second examines the effect of the barrier on the passage of water and other substances across the mucous membrane; and the third is a fluorescent microscopy study of the passage of fluorescent dyes into the epithelium in vivo, including the effect of saliva on this passage.