bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure at the dental adhesive—etched enamel interface
Authors: RETIEF D.H.
Published: June 2007

None of the materials presently available to the dental profession truly dhere to enamel and dentine. Conditioning of the enamel surface with phosphoric acid greatly increases the bonding of dental materials to tooth structure and the etching technique is now an accepted and widely applied procedure in dentistry.

During the development and laboratory evaluation of new dental materials, the resin‐enamel bond strength is determined by means of tensile loading tests. The site of failure is often recorded as occurring within the test material; partly within the material; at the adhesive‐enamel interface; within the enamel; or in a combination of these sites.

An epoxy resin formulation developed for the direct bonding of orthodontic attachments was used as the adhesive and enamel etched with 50% phosphoric acid as the adherend surface. Experimental bonds were subjected to tensile stresses to failure and both the enamel and adhesive aspects of the fractured bonds examined by scanning electron microscopy.

The results indicate that the sites of failure cannot be reliably classified by visual examination per se or under low magnification. A model is proposed to elucidate the characteristics of interfacial failures. This experimental model was tested by surface roughness profiles and atomic absorption spectrometry.
Co‐ordinates of jaw movements
Authors: VAN RENSBURG L.B. , LEMMER J. , LEWIN A.
Published: June 2007

The method of pantography can be used to record tracings representing the pattern of movement of the jaws. Such tracings can be subjected to analysis on a rectangular coordinate system of axes. All tracings appear to be rotations scribed about instanta‐neously moving axes. Since the tracings are composites of rotations about the x‐, y‐and z‐axes, they cannot be used to fully describe the jaw movements which produce them.

Notwithstanding this limitation, pantographic tracings are of value in the clinical demonstration of individual variations which exist in the patterns of jaw movements.
A comparative study of three etching solutions: effects on enamel surface and adhesive‐enamel interface
Authors: RETIEF D. H.
Published: June 2007

The chemical treatment of enamel surfaces is an approach in obtaining increased bonding of dental materials to tooth surfaces. Three etching solutions commonly used at present are 50% H3PO4, 50% H3PO4 attenuated with 7% zinc oxide and 50% citric acid.

The effects of these three conditioning solutions on normal and polished enamel surfaces and on the interfaces between untreated enamel and etched enamel surfaces were studied by scanning electron microscopy.

The variable etching pattern observed with each of the acids made a comparative study difficult. This was further complicated by the dependence of the etching action on prism orientation on polished enamel surfaces. Additional factors that have to be considered are the presence of prismless enamel and perikymata.

Surface profile recordings of polished and acid‐etched polished enamel surfaces provided some quantitative measure of the etching action of the conditioning solutions.

The 50% citric acid solution had the mildest etching action while 50% H3PO4 and 50% H3PO4 attenuated with 7% zinc oxide elicited comparable responses.
Polymethylmethacrylate as a denture base material in service
Authors: HARGREAVES A. S.
Published: June 2007

Assessments of the practical deficiencies of polymethylmethacrylate in service have been carried out by several workers. Some of these studies and one further one have been compared so as to seek any common factors, especially those concerned with the age of the appliance at failure. Times of vulnerability for different types of dentures have been demonstrated, and the scope for time‐based studies in the laboratory and in service has been discussed.
Doughing time of heat‐cured dental acrylic resins and its dependence on polymer particle size distribution
Authors: McCABE J. F. , SPENCE D. , WILSON H. J.
Published: June 2007

A simple method of determining the doughing lime of acrylic denture base materials is reported, It is suggested that the method described is suitable for standard specification testing.

In addition, the effect of temperature on doughing time and the correlation between doughing and polymer particle size distribution has been determined.
Masticatory function—a review of the literature
Authors: BATES J. F. , STAFFORD G. D. , HARRISON A.
Published: June 2007

A review and evaluation of the literature on mastication has been undertaken. Part Idiscusses the form of the masticatory cycle in the natural and artificial dentitions, including the controversial question of whether tooth contact occurs during function. Part II reviews the literature concerning the speed of movement of the mandible, rate of chewing, and the forces developed in chewing. Part III describes masticatory efficiency and performance, the effect of food on masticatory function, and incorporates a summary of all these three papers.
Frequency and location of artificial crowns and fixed partial dentures constructed at a dental school
Authors: VALDERHAUG JAKOB , KARLSEN KJELL
Published: June 2007

The material consists of patients who received single crowns and fixed partial dentures at the Department of Prosthetics, Dental Faculty, University of Oslo in the period 1967–73.

Two‐thirds of the patients were women, and about two‐thirds of the restorations were made in the maxilla. A total of 3275 crowns were received by 2145 patients. On average, maxillary teeth were crowned 7 years earlier than mandibular teeth. A total of 1393 fixed partial dentures, consisting of 6835 units, were made for 1368 patients.
Attrition: possible mechanisms of compensation
Authors: BERRY D. C. , POOLE D. F. G.
Published: June 2007

Attrition, or wear of the occlusal surfaces of the teeth, may not only be physiologically normal, but necessary for function. Since occlusal wear must lead to reduction in tooth length, significant dimensional changes in facial morphology are inevitable unless mechanisms exist to compensate for attrition. Secondary dentine formation, alveolar growth, and adaptive changes in the masticatory muscles can provide this compensation, and may be part of a complex system by which an effective level of masticatory function is maintained even when attrition is extreme.
Soft lining materials: composition and structure
Authors: McCABE J. F.
Published: June 2007

An analysis of five proprietary acrylic soft lining materials revealed that they can be classified into two groups. The first of these groups (Soft Oryl and Coe Soft) resemble the tissue conditioners in composition in that their liquid component contains no monomer. A study of their mechanical properties may reveal that these materials should, in fact, be classified as tissue conditioners.

The second group (including Palasiv, Virina and Coe Super Soft) were more conventional acrylic materials which differed in the amount of plasticizer and the type of acrylic monomer used in the liquid component and in the nature of the polymer component.
Enamel bonding plastic materials in modifying the form of abutment teeth for the better functioning of partial prostheses
Authors: PIIRTO MATTI , EERIKÄINEN ESKO , SIIRILÄ HANNU S.
Published: June 2007

The potential uses of enamel bonding sealants and composite filling materials in increasing the retentive form of abutment teeth and covering the preparations for the occlusal supports of partial prostheses were studied in laboratory conditions. The materials tested were Nuva and Concise sealants and composite resins.

Extracted permanent human molars, premolars and canines were inserted into acrylic blocks, two teeth in each block. An unretentive clasp framework was made on every test block. A retention prominence was built up separately of sealants and of composite materials occlusally to the tip of each clasp arm. The bond strength and wear resistance of the materials was tested in a device designed for this study.

The bond of the prominences was very good, only two out of 114 prominences loosened. The retention gained with prominences was, on average, 18 N measured by the force needed for removal. The decrease in the total retention of the four clasp arms was measured by the force needed to remove the clasp framework. The total retention of the prominences made of Nuva and Concise sealants after 5000 removals was 53 and 50% of the original, when long, flexible clasp arms were used. The corresponding figures for composite resins were 56 and 59%. Short rigid clasp arms caused a distinctly faster abrasion. The prominences made of sealants, in particular, were abraded rapidly, one‐fifth of retention being left after 3000 removals.
Short‐term changes in the perception of comfortable nandibular occlusal positions
Authors: TRYDE GERD , STOLTZE K. , FUJII H. , BRILL N.
Published: June 2007

In search of a new clinical method for determining the occlusal height of full dentures, the perception of the comfortable zone was studied in fifteen edentulous patients. In each experimental session perceptual changes were recorded from forty‐four consecutive applications of a screw jack per subject. Two stages in perceptual acuity were found. An initial stage, in which only minor variations occurred among the final screw adjustments which the subjects made when they assessed the borders of the comfortable zone. In the ensuing stage greater variations emerged, indicating a deterioration in the ability of the subjects to disciminate.
The NEED—DEMAND problem in patients with oro‐mandibular functional disorders
Authors: LOUS INGER
Published: June 2007

General conditions and facts concerning need‐demand will be discussed and applied to oro‐mandibular functional disorders. The balance between demand for treatment and offer of treatment will be considered and with this the importance of prevention, attention to the risk groups and early treatment will be shown.
The relationship between the metacarpal index and the rate of mandibular ridge resorption
Authors: WARD V. J. , STEPHENS A. P. , HARRISON A. , LURIE D.
Published: June 2007

This study tried to determine whether a relationship exists between the degree of alveolar resorption of the edentulous mandible and the degree of osteoprosis, as expressed by the metacarpal index. Eighty patients were examined. Each had a radiograph of the left hand to show the seocnd metacarpal, and a standard pan‐oral radiograph. A morphological measurement of the metacarpal bone, which is a good indication of the mineral content of the skeleton, was made on each hand radiograph. Alveolar resprption was estimated on the pan‐oral radiograph by taking the original height of the alveolar process as being three times the distance from the inferior border of the mandible to the inferior edge of the mental foramen. The regression analysis revealed no relationship between osteoporosis, as measured by the metacarpal index, and the amount of alveolar bone resorption.
The periodontium and restorative procedures
Authors: LEON A. R.
Published: June 2007

The literature associated with the effect on the periodontal tissues of restorative procedures has been reviewed. Opinions have changed from the assumption that only poor restorative dental treatment led to periodontal disease, to the present concept, that even clinically sound restorations, if positioned subgingivally, may be important aetiological factors in the initiation of periodontal disease.
The influence of the time of etching and washing on the bond strength of fissure sealants applied to enamel
Authors: WILLIAMS B. , von FRAUNHOFER J. A.
Published: June 2007

Variation of the etching and washing times of enamel surfaces prior to the application of fissure sealants affect the bond strength in differing ways. Depending on the length of the etch time, the effect of washing may increase or decrese the bond strength of the sealant. Clinically, the most satisfactory combination of etch and wash time was found to be different to that suggested by the manufacturers.
Colorimetric determination of the masticatory performance
Authors: KÄYSER A. F. , van der HOEVEN J. S.
Published: June 2007

A description is given of a colorimetric method to measure the masticatory function. It is based on the release of dye when chewing raw carrots. Information is given about the reproducibility of the method. The procedure takes 30 min for eitht tests on one subject and can be carried out with standard laboratory epuipment.
Differences in the physical properties of composite dental restoratives
Authors: LEE HENRY L. , ORLOWSKI JAN A.
Published: June 2007

A method for accelerated testing of dental composite restorative materials is described, and results of these tests are reported. The uniform testing showed considerable variation in the properties of the eight materials included in the study.
Dentine/pulp reactions to full crown preparation procedures
Authors: DAHL BJØRN L.
Published: June 2007

Scanning electron microscopy was used to study the formation of a dentine smear in ten premolars ground with a water‐cooled diamond in an air turbine. In another ten teeth the pulp reaction to full crown preparation with the same armamentarium was investigated by histological techniques. The findings revealed the formation of a dentine smear which was easily removed by light polishing with wet pumice, leaving plugs of debris in the tubule apertures. The clinical significance of these findings needs further investigation. No bacteria were demonstrated on the prepared surfaces either in the scanning electron micrographs or histologically when stained with Brown & Brenn stain. Severe, acute pulp reactions were observed subjacent to the dentinal tubules cut in full crown preparation. This technique should therefore be limited to superficial use only.
Reliability of preparation method for initial strength measurement of amalgam according to the ADA specification
Authors: SPANAUF A. J. , VERMEERSCH A. G. , VRIJHOEF M. M. A.
Published: June 2007

The ADA specification method for preparation of amalgam samples for tensile strength studies has been investigated. It was determined as being of acceptable reliability for comparison against normal clinical use of the material.
Linear dimensional changes of three luting agents
Authors: ØILO GUDBRAND , AMBJØRNSEN EIRIK
Published: June 2007

The linear dimensional changes during setting of a reinforced zinc oxide eugenol cement (Alumina EBA® Crown and Bridge Cement), a composite resin cement (Epoxylite 9080® Crown and Bridge ADhesive) and a zinc silico phosphate cement (Fluoro‐Thin® cement), have been studied. The measurements were performed on specimens placed on a mercury bath. The cements were allowed to set under various environmental humidity. The measurements of specimen length started 3 or 5 min after commencing the mix.

The EBA‐cement showed a maximum contraction of 0·4% after 7 days when setting under dry conditions. Under wet conditions the cement had an initial contraction the first day of setting, and thereafter an expansion. After 21 days specimens setting under 100% relative humidity showed 0·3% expansion, whereas specimens immersed in water attained the initial length.

The composite resin cement showed a contraction of 1·0% after 1 day when setting under dry conditions. Under wet conditions the specimens had an initial contraction of 0·8% the first day of setting being reduced to 0·4% during the next 20 days.

The zinc silico phosphate cement showed a maximum contraction of 3·0% after 7 days under dry conditions and 0·5% after 1 day under wet conditions.
The concept of the sagittal condylar guidance: biological fact or fallacy?
Authors: CHRISTENSEN L. V. , SLABBERT J. C. G.
Published: June 2007

The clinical concept of a sagittal condylar guidance pertaining to the human temporomandibular joint is discussed in the light of selected studies on the anatomy, radiography and cineradiography of this joint, and clinical attempts at recording a sagittal condylar guidance. It seems as if there is no single and well defined sagittal condylar guidance in vivo, and thus no single and well defined sagittal condylar guidance angle applicable to the adjustable articulator.
In vitro caries related to marginal leakage around composite resin restorations
Authors: ERIKSEN HARALD M. , PEARS GRAHAM
Published: June 2007

The histology of caries‐like lesions around composite resin restorations with and without marginal leakage has been studied. The lesions were generated from bacterial plaque growing in an in vitro system. Marginal leakage was prevented by an acid etch technique. Ground sections of the experimental teeth were studied by polarized light and microradiography. The caries lesions penetrated along conventional class V restorations with marginal leakage while restorations bonded to an acid etched enamel surface totally prevented this ingrowth.
Mast cells in masseter muscle in experimental bruxism in man
Authors: CHRISTENSEN LARS VESTERGAARD
Published: June 2007

Three human subjects performed tooth grinding for 25 min, and after 20 h biopsies of the right and left masseter muscles were examined for their contents of mast cells. In comparison with specimens from a control group of three subjects, there was an increase of degranulating mast cells in muscles that had performed bruxism.
Gnathosonic monitoring of patients with gnathic dysfunctions
Authors: WAKABAYASHI YASUO , WATT DAVID M.
Published: June 2007

The progress of 23 adult patients during treatment for gnathic dysfunctions was monitored by gnathosonic techniques and graphs of the fluctuations in occlusal sound duration were studied. It was concluded that this method gave a useful insight into the progress of patients under treatment and aided the assessment of the effects of treatment.
Viscoelastic properties of elastomeric impression materials
Authors: INOUE K. , WILSON H.J.
Published: June 2007

A method of measuring torsional shear modulus and rigidity of elastomeric impression materials has been developed and is described. In addition, the changes in viscoelastic properties of these materials during setting are discussed.
Role of mucin and albumin in saline polarization of dental amalgam
Authors: FINKELSTEIN G.F. , GREENER E.H.
Published: June 2007

Studies into the electrochemical nature and corrosion behaviour of dental amalgam have indicated the need for an artificial saliva formula that will accurately simulate the electrochemical properties of natural saliva. Existing formulae have been based on inorganic saliva constituent concentrations, without accurate representation of organic constituents.
Study of a classification of occlusion
Authors: WATT DAVID M. , WAKABAYASHI YASUO
Published: June 2007

A functional classification of occlusion based on the sounds produced by tooth contact was first proposed in 1970. The classification was found useful for identifying patients prone to gnathic dysfunctions as a significantly higher proportion of these patients were in Class C than in Class A. In the studies described in this paper other parameters of occlusion were measured to find if there were differences between the classes in addition to the differences in occlusal sound duration which identified the classes. The first study found highly significant differences in co‐ordination between Class A and Class C as measured by the coincidence of sound patterns. Many significant differences at the 1% level were found in the F test of samples of 5 successive occlusal sounds in series of 25 sounds in Classes A and C, but these differences diminished as the series of sounds was prolonged, suggesting that the subject's ability to find stable occlusal positions improved with successive occlusal contacts. No significant differences were found in time intervals between the sounds in different classes, but significant differences were found in masseter muscle activity in relation to the presence or absence of silent periods between occlusal classes. It was concluded that the functional classification of occlusion based on the duration of tooth contact sounds was valid.
Wear of combinations of acrylic resin and porcelain, on an abrasion testing machine
Authors: HARRISON ALAN
Published: June 2007

Wear tests of various combinations of acrylic resin and porcelain were made using a machine which was designed to test materials under conditions similar to those of masticatory function by simulating the loads, sliding distances, and contact times encountered in the human masticatory cycle. The results showed that the amount of wear of the two materials worn in combination depended on the nature of the surrounding medium and on the surface roughness of the opposing material. Acrylic resin showed good wear resistance provided no third party abrasive or opposing hard, rough surface was present. When a mild abrasive was incorporated in the system, the acrylic resin vs acrylic resin combination wore almost seven times more than porcelain vs porcelain. Clinical experience would suggest that this is a reasonably sound order of wear.
The in vitro fungicidal properties of Visco‐gel, alone and combined with nystatin and amphotericin B
Authors: THOMAS C.J. , NUTT G. M.
Published: June 2007

The in vitro effect of the tissue conditioner Visco‐gel, with or without the inclusion of nystatin and amphotericin B, upon Candida albicans, Candida krusei and Candida tropicalis, has been studied. Visco‐gel alone was completely inert and would therefore not be used without nystatin in the treatment of a denture stomatitis where a yeast infection was present. Amphotericin B became completely ineffective when mixed with Visco‐gel, but in control tests remained very active.
Credibility of morphologic and psychologic theories of TMJ pain‐dysfunction aetiology
Authors: KIRVESKARI PENTTI
Published: June 2007

An evaluation of the morphologic and psychologic theories of the aetiology of TMJ pain‐dysfunction can be revealing if made without resorting too much to scientific experimental results, because the interpretation of results as well as the questions asked are largely dependent on a prior commitment to one of the theories.

Accepting that the TMJ pain‐dysfunction became a common disease after the industrial revolution gives reason to look for a causative factor connected with it. Both an increase of psychologic stress and a change of dental morphology and function appear as possible factors, but only the latter has factual evidence. The lack of functional wear disturbs the unconscious swallow reflex but apparently not mastication. This suggests that retrusive interferences are a necessary but not always sufficient condition for the initiation of the TMJ pain‐dysfunction. Psychologic factors are contributory, they can cause tooth clenching and perhaps grinding, but there seems to be no reason other than interferences from occlusion for that taking place eccentrically. Thus psychogenic tooth clenching and grinding do not seem to be pathogenic without the morphologic factor.
Viscoelastic properties of elastomeric impression materials
Authors: INDUE K. , WILSON H. J.
Published: June 2007

A method of measuring the elastic recovery of impression materials after the application of a strain applied at the setting time is described. The results obtained using this method for a representative selection of impression materials are presented and discussed.
A study of the contour and external surface of Class V composite resin fillings
Authors: RAJSTEIN J. , TAL MICHAEL
Published: June 2007

Twenty‐five Class V Composite‐resin, Adaptic® fillings were prepared on extracted human teeth under five different matrices. White stones and flame diamonds were used as polishing devices. The smoothest surface was obtained with celluloid strip and the most acceptable contour obtained with preformed matrix.
The effect of denervation on trauma from occlusion
Authors: JOHANSEN JAN R. , KARLSEN KJELL
Published: June 2007

Trauma from occlusion was induced by inserting cantilever bridges bilaterally in the mandibles of two monkeys. In one monkey the mandibular nerve was cut on one side; in the other on both sides. By this procedure possible protective action of nerve receptors in the periodontal membrane was reduced. The occlusal trauma resulted in severe damage to the pulp and resorption of the roots, but no appreciable downgrowth of the crevicular epithelium.
Cusps or no cusps—that is not the question
Authors: KIRVESKARI PENTTI
Published: June 2007

Current views of the significance of cusps to oral health range from an emphasis on meticulous recusping of the restored teeth to a recommendation of gradual prophylactic elimination of natural cusps by grinding.

Cusps, their morphology and mutual arrangement are associated with masticatory function. The adaptive value of efficient mastication has diminished along with advancing cultural evolution. Industrialization marks a turning point as seen from the almost total disappearance of functional tooth wear. Restoring cusps to achieve maximum structural efficiency thus lacks a rational basis. But the occlusal morphology is also associated with the swallow reflex: retrusive occlusal interferences tend to disturb it. These interferences can be avoided by establishing the freedom in centric or by restoring the occlusion to the retruded position.

The prophylactic grinding of teeth also lacks a rational basis. The consequences of artificial wear are not likely to be the same as those of functional wear because the function has changed, the oral environment is different. It seems advisable, therefore, to try to eliminate only unquestionably harmful factors, and to leave the rest of the morphology as unchanged as possible.
Processing factors affecting the clarity of a rapid‐curing clear acrylic resin
Authors: KENG S.B. , CRUICKSHANKS‐BOYD D.W. , DAVIES E.H.
Published: June 2007

The difficulty in repeatedly producing unblemished, clear acrylic resin in the dental laboratory has hindered its wider use, despite its many advantages over coloured material. Recently, rapid‐cure dental acrylics have been introduced, which are available in both clear and coloured forms. This investigation examined various factors which may influence the production of unblemished, rapid‐curing, clear acrylic resin. Utilizing a quantitative assessment of clarity, the most important factor influencing the clarity of the resin is shown to be the choice of separating medium. Tin‐foil produces extremely high clarity, but alginate mould separator causes surface blanching. However, this surface blanching can be removed by polishing. Porosity, caused by too rapid curing, and stone model dryness are of only secondary importance. Possible water contamination of the monomer liquid due to accidental exposure only affects clarity at very high levels of contamination.
Possible factors in the adhesion of fissure sealants to enamel
Authors: WILLIAMS B. , VON FRAUNHOFER J. A.
Published: June 2007

The type of aqueous solution used to wash the enamel surface immediately after etching with orthophosphoric acid affected the tensile bond strength obtained. Washing with a 1% potassium chloride solution was found to effect an improved bond strength, but no difference was observed when different types of water were employed for this purpose. A similar finding of no difference in bond strength was obtained when the possible influence of electrostatic forces was eliminated.
Qualitative changes in dental plaque formation related to removable partial dentures
Authors: EL GHAMRAWY ESSAM
Published: June 2007

A study was performed on the microbial composition of dental plaque developing on fifteen abutment teeth in nine partially edentulous subjects. Bacteria were counted in samples of plaque which had formed on vestibular surfaces, and on proximal surfaces facing edentulous spaces, during a period when dentures were not worn, and then for a period when dentures were being worn. It was found that the presence of removable partial dentures favoured a proliferation of spiral organisms.
Book Reviews
Authors: Browne R. M. , Saunders M. , Franks A. S. T. , Carlsson G. E. , Edwards M. , Goodman P. E. , Foster T. D.
Published: June 2007

Books reviewed in this article.

Oral Disease By C. R. Renson.

A Colour Atlas of Periodontology By J. D. Strahan and I. M. Waite.

Journal of Clinical Engineering ED. BY Morton D. Schwartz.

Das Fiefergelenk im Zahnarztlich—Prothetischen Fall By A. H. Geering.

Speech Language and Hearing Normal Processes and Disorders By Paul H. Skinner and Ralph L. Shelton.

Begg Orthodontic Theory and Technique By P. R. Begg and P. C. Kesling.

Removable Orthodontic Appliances By T. M. Graber and B. Neumann.
Destruction of the soft palate and nose by tertiary ‘benign’ syphilis.
Authors: RAMSTAD TORE , TRAAHOLT LARS
Published: June 2007

A case of untreated tertiary syphilis involving the soft palate and nose is described and the treatment is outlined.

In view of the rising incidence of acquired syphilis the clinician should bear this disease in mind whenever atypical lesions are encountered.
Plaque recordings as a guide to the prognosis for partial denture treatment
Authors: GHAMRAWY ESSAM EL , Tryde Gerd
Published: June 2007

Separate mean plaque scores of the proximal surfaces of abutment teeth, which faced denture saddles, were obtained from thirty‐three subjects with removable partial dentures, following a period of ordinary tooth‐brushing and at the end of a period following instruction in specialized tooth‐brushing. With ordinary tooth‐brushing, the subjects were distributed in the upper range of plaque scores which was considered dangerous to periodontal health. With specialized tooth‐brushing the subjects showed lower mean plaque scores, but over a wider distribution. Thus patients are variously at risk when treated with partial dentures.
Masticatory efficiency
Authors: EDLUND J. , LAMM C. J.
Published: June 2007

A method for measuring masticatory efficiency is described as well as a mathematical formula expressing the masticatory efficiency as an index. A silicone compound was used as test material.

The masticatory efficiency index was calculated as the mean of the best four out of five consecutive measurements of masticatory efficiency calculated from a specially designed formula.
Ionic transport through bis‐glycidyl methacrylate films
Authors: WILLIAMS B. , VON FRAUNHOFER J. A.
Published: June 2007

Specific ion meter studies have shown that ionic transport through bis‐GMA fissure sealant films is selective and that dissolved fluoride ions disappear from the solution around tooth sections at a more rapid rate than do calcium and chloride ions. This would indicate that topical fluoridation of pits and fissures can still be effected after placement of a fissure sealant. A causative mechanism for this phenomenon has been postulated. Calcium exchange studies indicate that calcium is removed from the enamel and that the microsolubility of fissure sealed teeth in CaCl2 solution is increased by the preparative and sealing procedure used for the enamel.
Host response to two different designs of minor connector
Authors: RUNOV J. , KROONE H. , STOLTZE K. , MAEDA T. , El GHAMRAWY E. , BRILL N. , Tryde G.
Published: June 2007

Temperatures were recorded in thirty‐two gingival crevices adjacent to proximal surfaces of abutment teeth fitted with minor connectors of an open space design, and in thirty gingival crevices adjacent to proximal surfaces fitted with minor connectors of a closed design. During the 2 week experimental period, the twenty‐seven removable partial denture subjects who were involved in the study kept the accumulation of plaque to a minimum by applying specialized tooth‐brushing. Although an equal but small amount of plaque formed in both groups, the presumed minimal rise in temperature stimulated by this plaque did not prevent the two connector designs from showing disparate effects on the crevicular temperature. It was concluded that the open space design of minor connector is less conducive to irritation of the adjacent marginal gingiva than is the closed design.
The strength and fracture toughness of calcium hydroxide preparations
Authors: LLOYD C. H. , ANDERSON J. N.
Published: June 2007

The strength of a brittle material depends upon the toughness of the material itself and the degree of perfection with which it can be placed. This study shows that both the compressive and tensile strength of calcium hydroxide lining materials is dependent on the fracture toughness at unstable crack propagation, Kic, and the size, number and distribution of pores (which are the defects that nucleate fracture). Of the products tested here, Dycal possesses the greatest actual strength due to a higher than average Kic value and relatively few isolated small pores. However, the greatest potential for strength exists in Reocap which has a Kic value a factor of 2.4 greater than its nearest rival (Dycal). Unfortunately its strength, as determined here, is less than Dycal due to the large number of pores in close proximity to each other.
Otological manifestations in temporomandibular joint dysfunction
Authors: KOSKINEN JOUKO , PAAVOLAINEN MIKKO , RAIVIO MATTI , ROSCHIER JOHN
Published: June 2007

Forty‐seven patients with temporomandibular joint dysfunction were studied. A total of 100 subjective symptoms localized in the ear were encountered in thirty‐nine patients. The treatment of dysfunction eradicated or reduced 56% of these symptoms.

A hearing defect was established audiometrically in eight cases and the probable cause was outside the masticatory apparatus in seven cases. There was conceivably a causal relationship in one case between the patient's cochlear hearing defect and temporomandibular joint dysfunction. The neuro‐otological finding was pathological in nine cases, in three of which the causative agent was independent of the masticatory apparatus. The vestibular disturbance diagnosed in six cases may have originated from temporomandibular joint dysfunction, but this could not be confirmed.
Influences of temporomandibular articular mechanoreceptors on functional jaw movements
Authors: KLINEBERG IVEN
Published: June 2007

Contributions of temporomandibular (TM) articular mechanoreceptors to the control of jaw movement in man were investigated by tracking functional jaw movements. Functional envelopes were recorded by monitoring spatial changes of the lower incisor tooth, before and during unilateral and bilateral anaesthesia of the TM articular capsule. Regional anaesthesia provided reversible blockade of afferent impulse transmission from articular mechanoreceptors, thus reducing their contributory effects on jaw muscle motoneurone pools. Subsequent variations in the size and shape of the envelope of function occurred and were quantified by measuring the area changes. The results suggest that articular mechanoreceptors make a continuous contribution to reflex control of jaw movement.
Formulation and evaluation of a hydrophobic composite plastic
Authors: CRAIG R. G. , WANG T. K.
Published: June 2007

A hydrophobic co‐polymer, helptafluorobutylmethacrylate co‐para vinyl phenol, was compounded with ethylene glycol dimethacrylate and silanated quartz to produce a hydrophobic composite. The experimental composite had satisfactory working properties and had mechanical properties comparable to commercial composite but a higher modulus of resilience. The wear resistance was equal to or greater than the commercial composite depending on whether a two‐body abrasion test or a track width versus normal load test was used for the evaluation. The thermal coefficient of expansion and water sorption values were somewhat higher than those of commercial composites.
The curing pattern of photo‐initiated dental composites
Authors: DE LANGE C. , BAUSCH J. R. , DAVIDSON C. L.
Published: June 2007

In this study the curing of photo‐initiated composites was investigated. After irradiation, the material in an experimental cavity could be divided into three zones: zone A which showed physical properties comparable to those of chemical initiated composites, zone B which was markedly softer than the first one, and zone C which showed no signs of curing at all. The location of the zones was dependent on the energy of the u.v. radiation, the exposure time, the storage time, and the storage conditions. The uncured material of zone C showed no tendency to set. The clinical implications of the observations are discussed.
Proximal plaque accumulation with two minor connector designs
Authors: EL GHAMRAWY ESSAM , RUNOV J.
Published: June 2007

The relationship of plaque accumulation to two different designs of a proximal minor connector, was studied in twenty‐seven removable partial denture wearers. On thirty proximal surfaces adjacent to a closed space design, and on thirty‐two surfaces adjacent to an open space design, plaque formation was recorded using a plaque scoring system. Mean plaque scores were calculated separately for the two types of design, and no difference was found between the two sets of scores.
Roentgen cephalometric analysis of ridge resorption and changes in jaw and occlusal relationships in immediate complete denture wearers
Authors: TALLGREN A. , LANG B. R. , WALKER G. F. , ASH M. M.
Published: June 2007

In eighteen subjects assigned for immediate complete upper and lower dentures, roentgen cephalometric recordings were made before extraction of the residual anterior dentition and 3 weeks, 3 months, 6 months and 1 year after denture insertion. The cephalometric analysis was based on electronic measurements of linear and angular morphological variables and computer head plots generated from 177 reference points (Walker, 1967), derived for each subject for each of the five observation stages.

The reduction of the alveolar ridges was most rapid during the first 3 months of denture wear and particularly during the post‐extraction period of 3 weeks. The reduction in anterior height of the lower ridge was on average twice as great as that of the upper ridge. The ridge resorption and the accompanying settling of the dentures on the basal seats, measured from lead shots inserted in the dentures, brought about an upward rotation of the mandible with a resulting decrease in occlusal vertical dimension and reduction in overjet of the dentures. In accordance with the amount of ridge reduction, these changes showed great individual variation.
The rheological properties of polyelectrolyte cements
Authors: COMBE E. C. , WATTS D. C. , GREENER E. H.
Published: June 2007

The rheological behaviour of six setting carboxylate cements was studied by capillary techniques in the shear rate of 0.65–65 s−1 and the cements were found to behave as power law fluids. All cements became dilatant as setting progressed and the kinetics of apparent viscosity increase, were found to follow an exponential function of time, exp (mt), with m ⋍ 0.5.
Jaw muscle silent periods by tooth tap and chin tap
Authors: McCALL W. D. , HOFFER M.
Published: June 2007

Electromyographic silent periods from jaw closing muscles were elicited during a clench by tapping on the chin and on selected teeth both in asymptomatic subjects and in subjects reporting symptoms of temporomandibular joint dysfunction.

The mean duration in response to a chin tap was significantly shorter in the asymptomatic group than in the dysfunction group. No significant differences in mean duration elicited by tooth taps were found between groups. Other comparisons of mean durations such as among muscles, among teeth, or between chin taps and tooth taps failed to achieve statistical significance.
The interaction between lining materials and composite resin restorative materials
Authors: LINGARD G. L. , DAVIES E. H. , VON FRAUNHOFER J. A.
Published: June 2007

The effects of four lining materials, Dycal, Procal, Cavitec and Poly F cement on Adaptic and Concise have been investigated in vitro. The parameters studied were surface roughness, hardness and colour both with and without an intermediate (or bonding) resin being present between the restorative material and the liner.

The effects of the four liners on the composites varied both between the lining materials themselves and with the composite resin. Two materials, Procal and Dycal, had little interaction with the composites, provided an intermediate resin was used with the latter. Cavitec appeared to have an adverse reaction with the composites and Poly F, whilst having no effect on the colour of the composites, did increase surface roughness. The adverse effects of lining materials were ascribed to minor constituents, particularly methyl salicylate, present in the formulation.
The effect of mercury on the fatigue life of a dental gold alloy
Authors: LLOYD C. H. , BAXTER G. R. V.
Published: June 2007

A type IV platinized gold casting alloy has been subjected to fatigue testing. Contamination of the surface of test pieces with mercury substantially reduced the fatigue life. This reduction was found to depend upon both the load applied and the microstructure of the alloy. The reason for such dependence is discussed.
Photographic assessment of colour changes in cold and heat‐cure resins
Authors: WOZNIAK W. T. , MULLER T. P. , SILVERMAN R. , MOSER J. B.
Published: June 2007

A photographic method for assessing colour change was compared with an instrumental colorimetric procedure. Two denture base resins were stained in various solutions. Optical density changes of colour transparencies were measured with a transmission densitometer. Good agreement with the colorimetric technique was obtained after 15 days of staining over a range of F‐stops and bandpass filters.
Comparison of retruded axis articular mountings with and without applied muscular force
Authors: TEO C. S. , WISE M. D.
Published: June 2007

The study reported compared the positions of the horizontal axis of rotation of the condyles when R.A.P. registrations were taken on seven subjects using: (1) An anterior jig with chinpoint guidance.

(2) An anterior jig with chinpoint guidance and applied muscle force by the subject.

(3) An anterior jig with bilateral manipulation (i.e. bilateral support of the body of the mandible by the operator).

The results showed that the most superior positions were obtained with the technique using the anterior jig with chinpoint guidance and applied muscle force, which was also the most inconsistent technique. The technique using the anterior jig with chinpoint guidance was most consistent, and the mean difference between retruded axis position and intercuspal position using this technique was 0.31 mm on the right side and 0.34 mm on the left side.
A comparison of centric relation with maximum intercuspation based on quantitative electromyography
Authors: BUXBAUM J. D. , PARENTE F. J. , RAMSEY W. O. , STALING L. M.
Published: June 2007

The study concerned the nature of the alterations, if any, in muscle activity demonstrable when the mandible shifts from maximum intercuspation into its most retruded physiological relation (i.e. centric relation).

An integrator‐averager was used to determine μV average amplitude from masseter and temporal muscles in two maxillo‐mandibular positions, centric relation and maximum intercuspation, and three modes, first contact occlusion, chewing and swallowing. Vertical reference marks on the cuspids were used to quantitate horizontal deviation from maximum intercuspation to centric relation. Data were obtained from twelve subjects and analysed for variance.

Results demonstrated a significant increase in μV in all centric relation positions. Statistics yielded an F value of 5.88258 with a probability of 0005. Results suggest critical limitations in reliance on centric relation as a reference position during clinical therapy.
The surface finish of the new microfill restorative materials
Authors: LUI J. L. , LOW T.
Published: June 2007

Surface smoothness is an important requirement for restorative materials. Recently, restorative materials claimed to be inherently smooth in surface characteristics have been developed. Matrix‐formed and finished surfaces of five new microfill restorative materials were compared with two composite resins, an acrylic resin and a silicate cement by means of scanning electron microscopy. The results of this investigation indicated that the matrix‐formed surfaces of all the restorative materials studied were not altogether perfect. Polishing using sandpaper and cuttlefish discs produced a very smooth surface finish in the new microfill restorative materials, Estic microfill, Estilux microfill, Isopast, Isolux and Silar which was comparable to that of the acrylic resin, Sevriton. The composite resins, Adaptic and Estilux exhibited the worst surface finish and the silicate cement, Bio‐trey was intermediate. Finishing, using other finer polishing devices on four of the materials produced a further improvement in the surface finish.
Observation and comparison of polished composite surfaces with the aid of SEM and profilometer.
Authors: LAMBRECHTS P. , VAN HERLE G.
Published: June 2007

After cleaning with an abrasive toothpaste, fourteen polished composites were examined in vitro SEM and profilometrically. It was shown that the smooth surface composites kept a remarkable smoothness. The classic composites coarsened profilometrically eight times under these testing conditions, and the glass‐ionomers fourteen times. SEM pictures pointed out that the organic matrix was the weakest link for classic composites as well as for glass‐ionomer cements. The glass‐ionomers were the roughest group because of the large grain size, numerous cracks and porosities. The porosities hampered the roughness measurements in all materials and contributed to a large extent to the roughness of the products.
The relative movements of the chin and the mandible during chewing
Authors: JEMT TORSTEN , HEDEGÅRD BJORN
Published: June 2007

The suitability of the soft tissue over the chin as a reference point in studies of mandibular performance during chewing was investigated. The movements of reference diodes (LEDs), one on the chin and the other attached to a lower front tooth, were registered simultaneously using the Selspot system and analysed in relation to the reference system in this method.

With respect to chewing rhythm, the conformity of the behaviour of the two diodes‐or the two tissue locations‐was good, thus allowing the conclusion that a chin reference point is suitable for analysing chewing rhythm.

Vertical displacement and velocity were less marked with the chin reference than with the tooth reference, however, indicating that the skeletal part of the mandible moves within the tissues envelope. The difference in movement at maximal opening was significant, the magnitude of the difference being between 12 and 20%.

Lateral displacement seemed to be of similar magnitude, although a tendency towards larger movements of the chin point than of the tooth was found.
Subjective and objective evaluation of bruxing patients undergoing short‐term splint therapy
Authors: MEJIAS JUDITH E. , MEHTA NOSHIR R.
Published: June 2007

Subjective and objective criteria were utilized to evaluate the effectiveness of short‐term bite splint therapy on bruxistic behaviour. A simple bruxism monitoring device was used to check pre‐treatment and post‐treatment nocturnal bruxism. This preliminary study suggests that short‐term splint therapy is effective in eliminating mild to moderate facial pain and dysfunction while reducing bruxistic behaviour. The bruxism monitoring device is a simple and effective tool for diagnosing bruxism quantitatively.