bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Merkel Cells in Oral Epithelium Using Antikeratin and Antineuroendocrine Monoclonal Antibodies
Authors: Ness K.H. , Morton T.H. , Dale B.A. 
Published: November 2010

Merkel cells are a rare cell type located at or near the basal lamina of oral epithelia and epidermis. They are associated with nerves, and may function as touch receptors. Merkel cells are difficult to identify by routine light microscopy, but have been identified by electron microscopy and specific antibodies. We demonstrate here that Merkel cells can be identified by immunohistochemistry, using a monoclonal antibody (LK2H11, Lloyd and Wilson, 1983) to neuroendocrine granules, and a monoclonal antibody (35βH11, Gown and Vogel, 1982) to a 54-kD keratin generally located in simple epithelia but not in stratified epithelia. Human oral tissue was fixed in Carnoy's fixative, and adjacent serial sections were stained with the two antibodies. Individual positively-stained cells were generally located at the bases of rete ridges. Cells in the same position in adjacent sections stained with both antibodies. Essentially all cells (94%) staining for neuroendocrine granules also gave a positive reaction for the 54-kD keratin, evidence that a single Merkel cell contains neuroendocrine granules and the 54-kD keratin. Staining of epithelial sheets of human oral tissues revealed a linear distribution of Merkel cells along the bases of rete ridges. We conclude that antibodies to simple epithelial keratins and neuroendocrine granules may be excellent immunohistochemical markers for Merkel cells, thus facilitating future studies to examine changes in Merkel cells and their distribution in pathologic conditions. The observation that Merkel cells can be stained with an antikeratin antibody strongly supports the epithelial origin of these cells.
The Surface Area of the Adult Human Mouth and Thickness of the Salivary Film Covering the Teeth and Oral Mucosa
Authors: Collins L.M.C. , Dawes C. 
Published: November 2010

The surface area of the mouth was measured to calculate the average thickness of the salivary film which separates the opposing layers of the oral mucosa and which also overlies the dental plaque. The subjects were 10 adults of each sex, all of whom had essentially a full complement of teeth. Impressions were taken of the upper and lower jaws, the buccal and labial vestibular mucosa, and the ventral surface of the tongue, and stone models were cast. The dorsum of the tongue was assumed to have the same area as the palate plus that of the palatal surfaces of the upper teeth. The six separate areas considered were the teeth, the palate, the buccal and lingual gingival and alveolar mucosa, the buccal and labial vestibular mucosa, the ventral surface of the tongue, including the floor of the mouth, and the dorsum of the tongue. Aluminum foil, of known weight per unit area, was adapted to the models of the different regions of the mouth, and the surface areas were calculated from the weights of the foil. The mean total surface area of the mouth was 214.7 ± 12.9 cm 2, and there was no significant difference due to gender. The teeth, keratinized epithelium, and non-keratinized epithelium occupied about 20%, 50%, and 30% of the total surface area, respectively. Given that the average volumes of saliva present in the mouth before and after swallowing have been estimated to be 0.77 and 1.07 mL, respectively, it can be calculated that the average thickness of the salivary film in the mouth varies between 0.07 and 0.10 mm. Since we have previously assumed that dental plaque is washed by a relatively thick layer of saliva, the results have important implications with regard to diffusion of substances in and out of dental plaque and with regard to the sensation of oral dryness caused by fluid absorption through the oral mucosa or by salivary evaporation.
Effect of Incompatibility Stress on the Fit of Metal-Ceramic Crowns
Authors: Anusavice K.J. , Carroll J.E. 
Published: November 2010

The interactive effect of coping thickness and a positive thermal contraction mismatch between metal and porcelain on the fit of metal-ceramic crowns has not yet been experimentally determined. Previous studies have suggested that marginal distortion may be due to contraction differences, although finite element analyses indicate that these distortion effects should be negligible. The marginal gap between metal-ceramic crowns and prepared dies was determined under conditions designed to exaggerate distortion effects. These included the use of thin metal copings (0.1 and 0.2 mm), a chamfer preparation, an alloy with relatively poor creep resistance, and a large thermal contraction mismatch between the alloy and porcelain layers. Gap changes which resulted during porcelain firing cycles were relatively small, but larger marginal discrepancies developed in crowns prepared with a compatible porcelain during grinding and abrasive blasting procedures. This study conclusively demonstrates that incompatibility stress induced by a positive contraction mismatch is not a primary cause of marginal or generalized distortion of metal-ceramic crowns and suggests that external grinding and internal abrasive blasting of crowns are more likely causes of this effect.
Physical Model for Non-steady-state Dissolution of Dental Enamel
Authors: Patel M.V. , Fox J.L. , Higuchi W.I. 
Published: November 2010

The purpose of this study was to provide a rigorous theoretical understanding of the dissolution behavior of dental enamel over the entire time-course of demineralization and to simulate by computer an erosion-type caries lesion according to the physical "hydroxyapa tite model". The appropriate diffusion equations which accountfor simultaneous diffusion and equilibrium of all species in enamel pores, boundary layer, and bulk solution, and which also take into consideration surface reaction kinetics, were employed to allow for calculation of the micro-environmental solution concentration and changes in the min eral density as a function of time and distance within the enamel. This comprehensive physical model for non-steady-state enamel dissolution also explicitly takes into account changes in the diffusivity and the dissolution rate constant as a function of mineral density. Demineralization experiments were conducted in 0.1 mol/L sink acetate buffer (pH = 4.50, μ= 0.50) , with ground bovine dental enamel blocks of known surface area mounted (with beeswax) in a rotating disk apparatus. Mineral density profiles were quantified by means of contact x-ray microradiography. The physical model was used to predict mineral density profiles for given demineralization treatments. The experimental profiles agreed quite well with the predicted profiles, when the effective diffusivity of the enamel was assumed to be a function of porosity and when changes in surface area of the crystallites were taken into consideration.
Early Microbial Colonization of Permucosal Implants in Edentulous Patients
Authors: Nakou M. , Mikx F.H.M. , Oosterwaal P.J.M. , Kruijsen J.C.W.M. 
Published: November 2010

In edentulous patients, the microbial colonization of permucosal implants of sintered hydroxyapatite was studied. Samples were taken from mucosa and dentures before insertion of implants and from supra- and subgingival sites two to 10 weeks after insertion. In total, five patients and 10 implants with clinically healthy peri-implant tissues were studied. The samples were investigated by dark-field microscopy and anaerobic culture. The supragingival plaque of the implants was dominated by Gram-positive cocci and rods, the subgingival plaque by Haemophilus spp. and Veillonella parvula. A group of bacteria was found specifically related to the implants: Actinomyces odontolyticus, Peptostreptococcus micros, Haemophilus actinomycetemcomitans, Eikenella corrodens, Capnocytophaga sputigena, and Leptotrichia buccalis. Black-pigmented Bacteroides was not found in any of the examined samples. Spirochetes were observed in denture plaque samples and in supragingival plaque of the implants. It is concluded that bacteria known as potential periodontal pathogens colonize the permucosal implants in the first weeks after insertion. The presence of these species seems to be dependent on the ecological factors provided by the artificial gingival crevice of the permucosal implants in the edentulous mouth.
Comparison of Pain Associated with Mechanical and Chemomechanical Removal of Caries
Authors: Anusavice K.J. , Kincheloe J.E. 
Published: November 2010

Previous studies have indicated that a chemomechanical caries removal system (CRS) has been effective in minimizing the use of conventional mechanical instruments and that it may reduce the need for local anesthesia. In the present study, a comparison of the pain experienced both during treatment with a chemomechanical technique and during conventional caries removal (control) was made for each of 47 patients who initially were not given a local anesthetic. One of two dentists was randomly selected to examine and treat patients with a matched pair of carious teeth, and each pair of teeth was treated in a randomized order with the CRS or control procedure. Responses to the McGill Pain Questionnaire (MPQ) revealed a significantly higher level of pain (p < 0.025) associated with the conventional treatment compared with the chemomechanical procedure. A significantly greater number of patients (p<0.05) requested local anesthetic for the tooth subjected to the control procedure than for the tooth subjected to the CRS procedure. However, 72.3% of the patients did not request local anesthesia for either treatment, although pain was experienced by these patients in 46.8% of the control teeth and 27.7% of the teeth which received the CRS treatment. Of the 20 pain descriptor categories listed on the MPQ, the sensory categories accounted for the greatest mean number of pain descriptors selected for both the CRS (4.4) and control procedures (8.0), compared with the mean number of descriptors selected from the affective pain categories for the CRS (0.8) and control procedures (1. 0). These results suggest that sensory pain factors are more important than affective pain factors in controlling the overall discomfort of patients and the need for local anesthetic during caries removal and subsequent restorative procedures.
Distribution of Antigenic Determinants Between Actinomyces viscosus and Actinomyces naeslundii
Authors: Firtel M. , Fillery E.D. 
Published: November 2010

A total of 18 monoclonal antibodies was raised against whole cells of Actinomyces viscosus and Actinomyces naeslundii. The monoclonal antibodies were used to determine the cross-reacting patterns among 26 strains of these species. Eleven different antigenic determinants were found. The specificity profiles of the antibodies indicated that the antigenic determinants of A. viscosus and A. naeslundii were arranged in a complicated mosaic. Extensive cross-reactions occurred between A. viscosus strains and strains of "typical" and "atypical" A. naeslundii . However, cross-reactions were rare between the two groups of A. naeslundii. A. viscosus appears to occupy a "middle position" between the two A. naeslundii groups. In addition to their value in seroclassification, some of the monoclonal antibodies were found to be useful in the identification of these species. One monoclonal antibody appeared to be selective for the "typical" A. naeslundii group. A. viscosus and "atypical" A. naes lundii-specific antibodies were also found, though they did not label every strain in their respective clusters. A. viscosus detection might be improved if mixtures of monoclonal antibodies were used.
Comments on the Clinical Application of Fibronectin in Dentistry
Authors: Pearson B.S. , Klebe R.J. , Boyan B.D. , Moskowicz D. 
Published: November 2010

Several studies have demonstrated that citric acid demineralization of the root surface promotes tissue attachment. Since demineralization exposes collagen to which fibronectin binds, the role of fibronectin in the attachment of cells to the tooth surface has been of considerable interest. It is clear that fibronectin and other cell adhesion proteins can promote cell attachment to the tooth surface; therefore, attempts have been made to utilize these findings in a clinical setting. Using a quantitative ELISA procedure to measure the binding of fibronectin to demineralized bone and tooth, we have found that I μg fibronectin can saturate approximately 1 mg of either demineralized bone or demineralized tooth powder. Since serum contains 300 μg fibronectin per mL, the bleeding that occurs during oral surgery should saturate exposed tooth surfaces with amounts of fibronectin adequate for cell adhesion. Thus, exogenous fibronectin would appear to be of little clinical benefit.
Influence of Filler Type and Water Exposure on Flexural Strength of Experimental Composite Resins
Authors: Calais J.G. , Soderholm K.-J.M. 
Published: November 2010

The objective of this investigation was to determine the influence of water exposure on the flexural strength of three experimental composite materials. The composites consisted of an experimental resin system which contained silane-treated filler particles of quartz, barium glass, and porous silica. The amorphous silica particles were spheres approximately 5 μm in diameter. In addition to the different composites, pure resin samples were investigated as a control group. The results of this investigation did not support the hypothesis that use of porous amorphous silica filler particles reduced the hydrolytic degradation effect of composites containing such silica particles. Instead, the results indicated that water may have a more detrimental effect on the strength of the matrix than on the filler-matrix interface. However, the relatively high frequency of fracture lines in the porous silica particles after storage in water indicate that water had a weakening effect on this type of filler.
Eminence Development of the Postnatal Human Temporomandibular Joint
Authors: Nickel J.C. , McLachlan K.R. , Smith D.M. 
Published: November 2010

The objective of this study was to analyze postnatal eminence development quantitatively, as a first step in defining the relationship between loading of the TMJ and eminence development. A sample of human osteological remains provided the temporal bones of forty-nine (49) individuals of ages between birth and twenty years. An angular measurement technique permitted quantification of the degree of eminence development of each individual. It was concluded that: (i) the TMJ eminence reaches more than 50% of mature size, and exhibits mature morphology, by the time of completion of eruption of the primary dentition; (ii) the maximum velocity of development of the eminence takes place before three years of age; and (iii) the velocity of development of the eminence is reduced at about five years of age, and slowly diminishes to zero by the middle to late teens.
Fracture Mechanics Parameters for Failure Prediction of Composite Resins
Authors: De Groot R. , Van Elst H.C. , Peters M.C.R.B. 
Published: November 2010

This study contains the first part of a research project in which the applicability of fracture mechanics parameters to predict failure of a restored tooth was investigated. Fracture mechanics parameters have been used in dental research before, but were restricted to comparative studies between various brands of composites. The critical values of the opening mode stress intensity factor (KI), its equivalents, the strain energy release rate (GI), and the J integral (J I), were measured with single-edge notched-bend (SENB) specimens of dental composite in a three-point bend test. The measured values of K Ic for Silux (KIc = 0.99 ± 0.03 MNm-3/2) and P-30 (KIc = 1.88 ± 0.12 MNm-3/2), compared with values from the literature, show quantitative agreement. The J integral was computed by means of finite element analysis (FEA) on a two-dimensional model of the SENB specimens. The critical value of the J integral (measured with SENB specimens, notch depth-to-width ratio (a/W) = 1/2) was used to predict failure of specimens having an arbitrary geometry. In this study, failure was predicted for SENB specimens with notch depth-to-width ratio (a/W) = 1/4 and 3/4. The predicted deflection and load at failure correspond well with the measured deflection and load.
The Effects of Treatment on Masticatory Muscle Activity and Mandibular Posture in Myofascial Pain-dysfunction Patients
Authors: Burdette B.H. , Gale E.N. 
Published: November 2010

The purpose of this study was to evaluate tonic masticatory muscle activity and the postural rest position of the mandible, pre- and posttreatment, in patients with TM disorders. Forty-one patients diagnosed as suffering from myofascial pain-dysfunction (MPD) were evaluated, with electromyography (EMG) used to measure the muscle activity of the masseteric and anterior temporal areas at rest. Postural rest position was assessed by measurement of interocclusal distance. Twenty-three asymptomatic subjects were also tested as controls. Treatment for the pain group emphasized cognitive awareness of dysfunctional orofacial behavior and biofeedback training of the masseteric area to teach masticatory muscle relaxation. The pre-treatment EMG values of both the masseteric and anterior temporal areas were significantly higher for the pain group than for the control group. Post-hoc division of the pain group into successful and unsuccessful subgroups was made on the basis of the degree of symptom improvement. EMG activity decreased significantly in the masseters of both subgroups, but only the unsuccessful subgroup showed a significant decrease in anterior temporal activity following therapy. Interocclusal distance was significantly increased in both subgroups. These results suggest that tonic masticatory muscle activity may be elevated in MPD patients. They also suggest that a decrease in EMG activity in the masseter and anterior temporalis muscles and an opening of the postural rest position of the mandible may accompany completion of psychophysiological therapy, but these changes do not correspond directly with the outcome of that therapy.
A Histological Evaluation of a Functional Endosseous, Porous-surfaced, Titanium Alloy Dental Implant System in the Dog
Authors: Deporter D.A. , Watson P.A. , Pilliar R.M. , Howley T.P. , Winslow J. 
Published: November 2010

We have previously reported the clinical and radiographic findings of a trial in dogs of a new dental implant system after a functional period of eight months. The present report consists of the corresponding qualitative and quantitative histological data. The implant system was fabricated from Ti-6A1-4V and employed a porous-surfaced configuration to achieve implant fixation by bone ingrowth. A similar porous surface was used on the apical 1/3 of the transgingival collar in an attempt to gain ingrowth and attachment of gingival connective tissue. The qualitative histological data confirmed that white such attachment to the collar did occur for some implants, in the majority of implants (22 of 32) the parous region of the collar became contaminated with bacterial plaque, resulting in implant failure (four implants) or suggesting future implant failure (18 implants). Statistical analyses of the quantitative histological data indicated that there were no significant differences in surface contact of bone with the middle third of the porous implant surface (CLF) when initial healing interval (four or eight weeks), implant location, or aspect of implant (buccal vs. lingual vs. mesial vs. distal) were compared. However, comparison of the current group of functional implants with an earlier group of similarly implanted non-functional implants indicated that function produced a highly significant increase in CLF.
Improvement of the Caries Resistance of Human Dental Roots by a Two-step Conversion of the Root Mineral into Fluoridated Hydroxylapatite
Authors: Hoppenbrouwers P.M.M. , Groenendijk E. , Ramlochan Tewarie N. , Driessens F.C.M. 
Published: November 2010

Roots of extracted human molars were treated for both 10 and 30 min with a saturated solution of dicalcium phosphate dihydrate (DCPD) of pH 2.4 and subsequently with a 5.3 mmol.L -1 solution of sodium fluoride of pH 7.0. The objective of these combined treatments was to convert the highly-soluble root mineral into the less-soluble fluoridated hydroxylapatite, with DCPD as an intermediate, to improve caries resistance. The mineral content of the surface layer was not affected in a significant way. Roots treated in this way were subjected to 50 mmol.L-1 acetate buffer solutions of pH 5.5 and with pIOHA-values of 112, 116, and 122. The proportional reduction of the rate of demineralization (Vdem) of similarly treated roots subjected to buffer solutions of pIOHA 112 and 116 appeared to be equal initially. Since fluoridated hydroxylapatite is insoluble under these conditions, these findings are in agreement with expectations. The reduction of Vdem amounted to about 45 and 70% for roots treated for 10 and 30 min, respectively. When roots were treated for 10 and 30 min and then exposed to buffer solutions with a pIOHA 122, reductions of Vdem of about 30 and 55%, respectively, were found. Conversion of the root mineral into fluoridated hydroxylapatite can eliminate, in principle, the existing difference in caries susceptibility of the root and of the dental enamel.
A Scanning Electron Microscope Study of Monkey Maturation-stage Ameloblasts
Authors: Skobe Z. , Prostak K.S. , Stern D.N. 
Published: November 2010

The maturation-stage enamel organs of Macaca arctoides and Macaca mulatta were examined in order to determine whether the cells were similar to those of the continuously erupting rat incisor. Tooth buds of the permanent dentition were fixed in fonnaldehyde-glutaraidehyde and post-fixed in OsO4. The enamel organs were separated from the enamel during dehydration, critical-point-dried, metal-coated, and examined in a scanning electron microscope. The results showed that there were few differences in the morphology of maturation-stage ameloblasts of these primates compared with those of other species reported in the literature. The apical plasma membranes were either smooth- or ruffle-ended, while the later mem branes had maze, microvillous, or ridge configurations, also seen in rats, and an additional configuration of interdigitating bulbous extensions. The blood vessels of the papillaiy layer in monkeys were about 7 μm in diameter, considerably larger than those of the rat.