Biomedical subjects
Publications and source records attributed to H P de Jong.
For the restoration of occlusal anatomy partial gold restorations are preferred. Adhesive techniques in combination with plastic materials can also be used and are less invasive than indirect restorations. Occlusal tooth wear is becoming a major problem all over the world. This paper describes minimal invasive techniques to restore tooth wear.
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As part of a validating process, tests and indices for dysfunction of the temporomandibular joints and masticatory muscles were compared and correlated in 211 persons with an almost complete or complete natural dentition. Helkimo's Clinical Dysfunction Index (CDI), the Mandibular Dysfunction Symptoms (MDS) scale from the "Erweiterter Giessener Beschwerdebogen", the Modified Half-Minute (MHM) test and the palpation test for the stomatognathic system (PALP-test) were compared. The PALP-test had the highest internal consistency (coefficient alpha = 0.92) and the highest intercorrelation with the CDI. Furthermore, it was found that the PALP-test and the CDI probably yield the most realistic distribution of persons in the three classes no symptoms, mild to moderate and severe, and also show the highest percentage of absolute correspondence. The MDS-scale and MHM-test scores showed little dispersion and probably indicated too much or too little pathology. The correspondence between the last two measures is mainly due to an overrepresentation of the middle scoring class (mild to moderate indication of dysfunction of the temporomandibular joints and masticatory muscles). In screening procedures this can easily result in an overrepresentation of people with supposed pathology.
Disadvantages of Helkimo's Clinical Dysfunction Index have led to the introduction of a palpation test of 20 sites for grading the severity of dysfunction of the stomatognathic system. The reproducibility of this palpation test was studied using two experienced dentists and two first grade dental students to examine the subjects. Measurements of maximal mouth opening were carried out for comparison. The intra- and interexaminer reproducibility was found to be satisfactory for both the dentists and the students, showing that for this test good training is as important as clinical experience. The palpation test has the advantage that it is fast (60 s) and is an interval scale, which is especially important for epidemiologic and correlational studies.
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A total of 211 persons with a complete natural dentition were examined for signs and symptoms of the TMJ pain dysfunction syndrome. They also answered the questions of the Dutch version of the Hopkins Symptoms Check List (HSCL). Schooling, age and sex were also registered. Signs and symptoms of the TMJ pain dysfunction syndrome proved to be highly correlated to the psychologic and somatic scales of the HSCL with one exception: maximal mouth opening. The total palpation score proved to be a reliable, sensitive, easy and fast predictor for the severity of the TMJ pain dysfunction syndrome.
The adhesion of the oral bacterium Streptococcus sanguis CH3 to various polymeric surfaces with surface free energies (gamma s) ranging from 22 to 141 erg cm-2 was investigated. Suspensions containing nine different bacterial concentrations (2.5 X 10(7) to 2.5 X 10(9) cells per ml) were used. After adhesion for 1 h at 21 degrees C and a standardized rinsing procedure, the number of attached bacteria per square centimeter (nb) was determined by scanning electron microscopy. The highest number of bacteria was consistently found on polytetrafluorethylene (gamma s = 22 erg cm-2), and the lowest number was found on glass (gamma s = 141 erg cm-2) at all bacterial concentrations tested. The overall negative correlation between nb and gamma s was weak. However, the slope of the line showing this decrease, calculated from an assumed linear relationship between nb and gamma s, appeared to depend strongly on the bacterial concentration and increased with increasing numbers of bacteria in the suspension. Analysis of the data for each separate polymer showed that the numbers of attached cells on polyvinyl chloride and polypropylene were higher but that those on polycarbonate were lower than would be expected on basis of a linear relationship between nb and gamma s. Desorption experiments were performed by first allowing the bacteria to attach to substrata for 1 h, after which the substrata and attached bacteria were removed to bacterial suspensions containing 10-fold lower bacterial concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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An experimental technique is described to determine contact angles on bacterial layers deposited on cellulose triacetate filters. Measurements with water, water-n-propanol mixtures, and alpha-bromonaphthalene were employed to calculate surface free energies of various oral bacteria. Differences of 30 to 40 erg cm-2 were obtained for four different bacterial species isolated from the human oral cavity, if the concept of dispersion and polar surface free energies is applied. The free energies obtained were used to calculate interfacial free energies of adhesion of these bacteria from saliva onto tooth surfaces. Bacterial adhesion is energetically unfavorable, if the enamel surface free energy is less than 50 erg cm-2.
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The surface free energy gamma s and its polar and dispersion components gamma Sp and gamma Sd were determined from contact angle measurements on human enamel treated with sodium fluoride, acidulated phosphate fluoride (APF), and aminfluoride solutions. Sodium fluoride solutions only slightly influenced the surface free energy component gamma Sp. The gamma Sp value of the APF-treated human enamel increased from 52 to 66 erg X cm-2. The gamma Sp value after aminfluoride treatment decreased from 52 to 19 erg X cm-2. The gamma Sd values remained about 35 erg X cm-2 for all specimens measured. It is suggested that aminfluoride-treated enamel surfaces may exhibit a reduced tendency for bacterial adhesion.
The surface free energy is a definite factor in the adhesion of micro-organisms to host surfaces, such as tooth surfaces. The surface free energy gamma s can experimentally be determined by means of a series of contact angle measurements with various liquids. Employing the concept of polar and dispersion components, it was found, that gamma s of ground and polished human enamel is 88 +/- 9 erg.cm-2. This value is of the same order of magnitude as obtained for hydroxyapatite (the main mineral component of enamel) and fluorapatite. Fluoride applications on human enamel, frequently employed in dentistry, greatly influence the surface free energy. Application of various fluorides gave different results: Aminfluorides reduced gamma s to 62 +/- 5 erg.cm-2; APF raised gamma s to 107 +/- 11 erg.cm-2; NaF hardly influenced gamma s X gamma s remained 87 +/- 9 erg.cm-2. Adsorption of salivary proteins (pellicle formation) influences these differences. In vivo pellicle formation on FEP (gamma s = 17 erg.cm-2) increased gamma s to 41 erg.cm-2, Diacryl (gamma s = 76 erg.cm-2) increased gamma s to 117 erg.cm-2, while on sintered hydroxyapatite (gamma s = 80 erg.cm-2) gamma s increased to 118 erg.cm-2.
In this study, the dispersion (gamma ds) and polar (gamma ps) surface free energies of human enamel with and without an acquired enamel pellicle and of crystalline hydroxyapatite were determined from contact angle measurements. The results show that gamma ps is strongly influenced by the presence of a pellicle; the total surface free energy (gamma s) is considerably smaller for enamel with an acquired pellicle than for enamel without an acquired pellicle. Enamel without an acquired enamel pellicle shows surface free energies comparable with those of crystalline hydroxyapatite.
Cell spreading and cell division rates of a transformed line of mouse lung fibroblasts were studied on various polymer surfaces in the presence of serum proteins. The bare polymer surfaces, as well as the protein-coated surfaces, were characterized by their polar (gamma ps) and dispersion (gamma ds) surface free energies. Cell spreading appeared to be dependent on the polar surface free energy. Cell spreading is low when the gamma ps of the bare surface is lower than 5 erg cm-2; marked spreading occurs when gamma ps is higher than 15 erg cm-2. A similar relationship was found between cell spreading and polarity of the protein-coated surfaces, although less pronounced than for the bare surfaces. Cell spreading appeared independent of the dispersion surface free energy. Cell division rate was the same on all surfaces tested.
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