bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of experimental interfering occlusal contacts on the postural activity of the anterior temporal and masseter muscles in young adults
Authors: RIISE C. , SHEIKHOLESLAM A.
Published: June 2007

The effects of an intercuspal occlusal interference on the pattern of postural activity of the anterior temporal and masseter muscles were studied in eleven volunteers with complete, natural dentitions. The results indicate that, in man, there is postural activity in the anterior temporal and sometimes in the masseter muscles. The pattern of postural activity is influenced by the occurrence of an experimental occlusal interference, sometimes as early as 1 h after the insertion. After 48 h there was a significant increase of the activity in the anterior temporal muscles. This increased activity persisted until the interference was removed 1 week later and had almost disappeared 1 week after the removal.
The strength of lining materials under constraint
Authors: LLOYD C. H. , JEFFREY I. W. M. , MANNION M. J. P.
Published: June 2007

The compressive strength of the lining material Dycal was found to increase when peripheral constraints were applied to its deformation. The stress required to produce fracture under such circumstances increased with the degree of constraint. In each case, by summing all the stresses in a yield criterion (Von Mises) the strength is understood. Materials previously used with caution because of low (compressive) strength may now be used with more confidence when external support and confinement exists.
Juvenile periodontitis: an historical review
Authors: SAXBY M. S.
Published: June 2007

A review of the literature on juvenile periodontitis has been undertaken. This paper traces the historical development of the appreciation of the condition. Some of the numerous early attempts to define a systemic background are noted, and the concept of ‘periodontosis’ and its subsequent influence, e.g. on epidemiological and clinical studies are discussed. The refining over the last 20 years of the concept of aggressive periodontal disease in the young is recorded. The patterns of bone loss in juvenile periodontitis and some forms of treatment are presented, together with evidence on its histopathology. Recent research has tended to concentrate on the microbiology and immunological background of juvenile periodontitis and a number of these studies are discussed.
An in vitro study of caries prevention, cavity adaptation, homogeneity and microleakage of a new fluoride‐releasing resin
Authors: TURPIN‐MAIR J. S. , RAWLS H. R. , CHRISTENSEN L. V.
Published: June 2007

A newly developed fluoride‐releasing composite and sealant were tested, in vitro, with regard to homogeneity, cavity adaptation, microleakage, and its effect on the extent of an artificially induced carious attack. Compared with a commercially available composite, the fluoride‐releasing material showed more desirable properties in combating caries, in uniformity of internal structure, and in microleakage.
Occlusal relationship in patients with pain‐dysfunction symptoms in the temporomandibular joints
Authors: De BOEVER J. A. , ADRIAENS P. A.
Published: June 2007

A total of 135 patients (thirty‐three males, 102 females) seeking treatment for pain and dysfunction of the TMJ were divided into five subgroups using the clinical dysfunction index of Helkimo.

No relation could be found between the number of occluding molars and premolars and the severity of the symptoms nor the evolution of the complaints.

A weak correlation was found between the outcome of the treatment with the occlusal splint and occlusal adjustment, and the above mentioned occlusal parameters (r=0.47).
Post‐surgical prosthodontics: clinical notes
Authors: BENINGTON IANC.
Published: June 2007

This paper discusses some of the problems and techniques that are involved in the prosthetic management of patients who are to undergo surgery to the upper and lower jaws. It stresses the importance of a close relationship between the surgeon and the prosthodontist so that the necessary treatment plan may be prescribed pre‐operatively rather than post‐operatively. The dental management where maxillary surgery is anticipated is discussed under the following headings: Pre‐operative assessment; Pre‐operative treatment; The operation; Post‐operative care; The intermediate obturator; The definitive obturator.

Where surgery is anticipated in the lower jaw the problems are related to whether the patient has lost all the mandibular bone on one side or only the alveolar section and whether they are able to retain any of the lower teeth to stabilize the appliance. However, even when edentulous, these patients are now able to control their lower appliance much better since the advanced plastic and maxillo‐facial surgical techniques produce a good denture‐bearing area and less mandibular deviation.
The significance of cusps
Authors: LUKE D. A. , LUCAS P. W.
Published: June 2007

It has been argued that the prolonged retention of cusps in the human dentition is a relatively recent aberration due to the negligible abrasiveness of modern diets and that to achieve maximum efficiency and freedom from disease human teeth should be worn down as they are in many herbivorous mammals. Here we critically review the evidence that has been put forward to support this idea and, after discussing the design of occlusal surfaces in relation to the wide variety of mammalian diets, we conclude that cusps are adaptations for breaking food with specific physical properties.
Evaluation of the cytotoxicity of four dental materials in vitro assessed by cell viability and enzyme cytochemistry
Authors: MERYON S. D. , BROWNE R. M.
Published: June 2007

The cytotoxic effects of zinc phosphate and silicate cements, Concise composite and zinc oxide/eugenol were evaluated after 24 h in an in vitro system which simulates the clinical usage of the material, and the results compared with those using phenol. Data of gross changes affecting cell viability placed these materials in ranking order of increasing severity: Concise < zinc phosphate < Silicap ≪ zinc oxide/eugenol. More discrete changes involving alterations in enzyme cytochemistry were assessed and the significance of the results discussed. The presence of dentine powder in the system reduced the cytotoxic effects on these materials.
An investigation of the reproducibility of face‐bow transfers
Authors: GOLD B. R. , SETCHELL D. J.
Published: June 2007

An investigation was conducted to determine the reproducibility of the position of a maxillary cast in two widely‐used semi‐adjustable articulators when a face‐bow transfer was repeated ten times for the same individual.

The results obtained with the Dentatus AEB, Whipmix Quickmount and Almore transfer bows were compared. The variations in cast position rarely exceeded ±1.0 mm in any of three planes of space and although the results suggested a ranking in accuracy of the three instruments, all were considered clinically acceptable.

On the basis of the results observed, face‐bow transfer appears to be a reliable clinical procedure and accuracy in the determination of reference locations is unlikely to be negated by subsequent transfer errors, provided that appropriate care is employed.
The influence of polishing on the marginal integrity of amalgam restorations
Authors: LETZEL H. , VRIJHOEF M. M. A.
Published: June 2007

The influence of the polishing procedure on the marginal integrity of amalgam restorations was investigated in a clinical study. In this study two operators each made 150 class I or II restorations in a group of forty‐eight adult patients. The restorations were made in a series of six per patient. Within each series, two restorations were made of three different high copper amalgam alloys. Only one restoration of each pair was polished. From each restoration a black and white photograph was taken after finishing and after 0.5, 1.0 and 1.5 years. The marginal integrity of each restoration at the four time periods was quantified with a 6‐point photo rating scale. The quantifications were analysed as to their variance for the factors alloy, polishing procedure, operator and patient.

After finishing, all four factors had a significant influence on the marginal integrity. From 0.5 to 1.5 years, the influence of the factors alloy, polishing procedure and patient were very significant. The influence of the patient on marginal integrity was more or less equal to that of the alloy. The size of the polish influence was relatively small. Therefore, it was concluded that the contribution of the polishing procedure to the prevention of marginal deterioration was questionable.
Long‐term influences on marginal fracture of amalgam restorations
Authors: LETZEL H. , VRIJHOEF M. M. A.
Published: June 2007

A clinical study was conducted in which two operators made 180 class I or II amalgam restorations in a group of fifty‐seven adult patients. The restorations were made in a series of six per patient. Each restoration was made of a different alloy (five conventional composition alloys and one high copper alloy). During a period of 5 years the marginal fracture formation of all restorations was yearly quantified with a 6‐point photo rating scale. The quantifications were analysed as to their variance for the factors alloy, patient and operator. The relative importance of significant factors was calculated.

The results show that for a period of 5 years the alloy, patient and operator all had a significant influence on the marginal fracture formation. The operator influence was stable in time. This factor was relatively small because the operator sample was highly selected. After 1 year the influence of the patient on marginal fracture was equal to that of the alloy. The patient influence in time was stable. However, the alloy influence increased considerably. The longer the service time of the amalgam restoration the more important becomes the influence of the alloy on the marginal fracture formation.
A differential thermal analysis (DTA) for the heats of reaction and temperature rises produced during the setting of tooth coloured restorative materials
Authors: LLOYD C. H.
Published: June 2007

Differential thermal analysis (DTA) has been used to obtain the temperature rises produced during the setting of a range of tooth coloured restorative materials, which included silicates, glass ionomers and composites. These have been compared on the basis of the temperature rise per unit volume of material. Calibration of the areas under the reaction peaks (produced during this isothermal operation) to obtain heats of reaction is discussed and a method described. As for the temperature rises, values are given per unit volume of material. The results are compared with those reported in other studies from which DTA is seen to be a technique suited to the determination of these parameters and which might be considered for use a standard method.
Physiological reactions to stress in subjects with and without myofascial pain dysfunction symptoms
Authors: MOSS ROBERT A. , ADAMS HENRY E.
Published: June 2007

Myofascial pain dysfunction syndrome and temporomandibular joint (TMJ) dysfunction syndrome have been suggested as resulting from masticatory muscle hyperactivity. Furthermore, this hyperactivity has been viewed as a response‐specific reaction to stress. The present study was designed to assess the effects of laboratory‐induced stress (i.e., startle stimulus, buzzer series, serial sevens tasks, and pain threshold/tolerance tests) on physiological responses (i.e. bilateral masseter EMG, skin conductance level, and heart rate) of ten patients (TMJ pain) with a history of facial pain and TMJ sounds. The two control groups, one with TMJ sounds only (TMJ sound) and the other with no history of these symptoms (non‐TMJ), were matched for sex and age. The results indicated that the TMJ pain group did not exhibit different masseter EMG levels when comparing symptomatic versus asymptomatic sides. Few significant differences were noted in the masseter EMG recordings of the TMJ pain and non‐TMJ group, while no difference occurred between the EMG levels of the TMJ pain and TMJ sound group. Little support was found for the assertion that TMJ pain subjects show greater EMG reactivity and less adaptation than do non‐TMJ subjects. Finally, no differences were found among groups in relation to the latency to ischaemic pain onset or tolerance. The discussion focuses on reasons for the findings of the present study being discrepant from previously reported research.
Analysis of factors influencing the long‐term effect of treatment of TMJ‐pain dysfunction
Authors: MEJERSJÖ CHRISTINA , CARLSSON GUNNAR E.
Published: June 2007

A follow‐up study on 154 females was performed approximately 7 years after the start of treatment for TMJ pain dysfunction. At the follow‐up the function of the patients' masticatory system had on average greatly improved. The individual variation was great, however. In this paper the influence of such factors as diagnosis, age, general health, occlusal disharmonies, dentition and social environment on the long‐term effect of treatment was analysed.

Patients with TMJ osteoarthrosis had, on average, no more signs or symptoms of dysfunction at the follow‐up than those judged to have had mainly neuromuscular problems. Poor general health was found to have a negative influence both on the immediate response to treatment of TMJ pain dysfunction and on the long‐term prognosis. Few correlations were found between occlusal factors and dysfunction. Occlusal interferences showed no correlation to dysfunction at the first examination and at the follow‐up were mainly correlated to some reported symptoms.

Loss of molars and premolars was correlated to impaired TMJ‐function.

The patients with repeated periods of treatment (14%) did not differ from the rest with respect to signs and symptoms of dysfunction at the follow‐up. In eight patients with extremely long periods of treatment general health problems and/or psychosocial factors were evident.
The effect of ultrasonic scaling on the surface of Class V amalgam restorations—a scanning electron microscopy study
Authors: RAJSTEIN J. , TAL M.
Published: June 2007

Class V cavities were prepared on twelve extracted teeth and then filled with amalgam which was condensed in six cases by hand and six by mechanical means. SEM records were obtained before and after ultrasonic scaling of the restored area. They showed that such scaling had a deleterious effect on the surface of the amalgam and its marginal integrity. However the mechanically condensed specimens were less affected.
The hardness of composites as a function of temperature
Authors: GREENER E. H. , GREENER C. S. , MOSER J. B.
Published: June 2007

The microhardness of conventional, posterior and microfil composites were measured as a function of temperature in an aqueous environment. With the exception of one posterior composite and two microfils, the composites suffered dramatic decreases in hardness (of the order of 30–50%) over temperature intervals corresponding to that encountered in oral service. In those systems which did not display hardness changes, interactions between glass and matrix as well as enhanced filler packing may be important.
The in vivo corrosion of Dispersalloy
Authors: McTIGUE D. , BRICE C. , NANDA C. R. , SARKAR N. K.
Published: June 2007

The in vivo corrosion of Dispersalloy amalgam restorations was characterized by scanning electron microscopy and energy dispersive X‐ray analysis. It was observed that the corrosion of CuSn resulted in pitting on the restoration surface. Corrosion of Sn‐rich grain boundaries led to intergranular separation of γ1 grains. The tin released through corrosion reacted with Ca, P, Cl and O forming various insoluble complexes on the external surface, at the tooth‐amalgam interface, and within the interior of the restoration. The demineralization of the amalgam‐adjacent margin has been attributed to corrosion.
Attachment retained overdentures: a report on their maintenance requirements
Authors: SHAW M. J.
Published: June 2007

Twenty‐three patients who received attachment retained overdentures between 1964 and 1977 are reviewed. One third of the patients examined had carious abutment teeth, oral hygiene was poor, and periodontal disease prevalent. Overdentures opposed by natural teeth required more extensive prosthetic maintenance than overdentures opposed by a conventional complete denture. Three quarters of the teeth retaining the prostheses were functioning adequately after a mean period of 7 years.
A 4 year follow‐up study of alveolar bone height influenced by two dissimilar Class II amalgam restorations
Authors: FISHER D. , MARKITZIU A. , FISHEL D. , BRAYER L.
Published: June 2007

Fifty‐four paired, approximal amalgam fillings, extended (E) versus unextended (NE) were placed in forty‐three patients and followed up to 4 years. Yearly measurements between the alveolar crest and (a) the apical margin of the fillings (E, NE), and (b) the cemento‐enamel junction of the control group, were performed using bite‐wing radiographs joined to a translucent grid magnified ten‐fold. The rate of alveolar crest resorption was similar for the control (C) and the unextended filling (NE) and reached 0.45 mm after 4 years of follow‐up. The resorption of the alveolar crest under the extended (E) filling was significantly higher and reached 0.80 mm after 4 years (P<0.001).
New sustained release dosage form of chlorhexidine for dental use: use for plaque control in partial denture wearers
Authors: HIRSCHFELD Z. , FRIEDMAN M. , GOLOMB G. , BEN‐YAACOV D.
Published: June 2007

The aim of this work was to test the effectiveness of a local sustained release application of chlorhexidine in prevention of plaque formation in a group of five partial denture wearers when oral hygiene procedures were withdrawn. The clinical study demonstrates that coating of the partial dentures with ethyl cellulose polymer containing the drug, prevents accumulation of plaque during a period of 12 days. No typical side effects of chlorhexidine such as tooth staining and unpleasant taste were observed during the study.
Microprobe analysis of dental amalgam alloy particles of Ag‐Cu eutectic composition
Authors: BRYANT R. W.
Published: June 2007

An electron microprobe was used to investigate the composition and microstructure of commercially available, and experimental dental amalgam alloy particles of approximately Ag‐Cu eutectic composition. The method of alloy and amalgam specimen preparation and the technique used in microprobe analysis have been briefly outlined. The dispersant particles in one commercial alloy were of Ag‐Cu eutectic composition (28.1% Cu), in another commercial alloy they were Cu‐rich (31% Cu). Although the dispersant particles were predominantly of uniform appearance, there was evidence in some particles of an internal structure pattern, small spherical inclusions or voids. The possible composition of the Cu‐rich inclusions was investigated using particles from an experimental alloy of approximately Ag‐Cu eutectic composition.
A method to determine the loss of substance of dental restorations
Authors: VRIJHOEF M. M. A. , LETZEL H. , HENDRIKS F. H. J.
Published: June 2007

A method is described for quantitative in vivo wear measurements on Class I and II composite restorations. Class I gold inlays were made in an acrylic premolar and molar. Over the occlusal parts of the teeth cast silver caps were made after releasing the surface of the inlay with tinfoil. Wear on the restorations was simulated by grinding away some gold from the inlay. Silicon impressions of the teeth were made with the caps both before and after this simulation. The volume and the average thickness of the removed gold was measured from the weight of the enclosed impression material in the cap before and after the wear simulations, the density of the tinfoil and the impression material as well as thickness and the weight of the tinfoil‐release.

Values expected for the volume and the average thickness of the removed gold were calculated from the weight of the restored acrylic teeth before and after the wear simulation, the weight, the density and the thickness of the tinfoil and the density of the gold used for the inlays. Measured and expected values are linearly correlated (r=0.97). An average wear thickness of the occlusal surface of a particular tooth of at least 30 μm can be detected. Because of its simplicity, inexpensiveness and accuracy the wear measurement method is highly productive and suitable for large scale and long‐term clinical research on the wear behaviour of posterior composites.
Results of epidemiological examinations of the temporomandibular joint in adolescents and young adults
Authors: GROSFELD O. , JACKOWSKA M. , CZARNECKA B.
Published: June 2007

An epidemiological investigation of the temporomandibular joint in 800 persons was undertaken, including two groups of 400 persons aged 15–18 and 19–22 years. The numbers of boys and girls was about the same. Interview and clinical examination comprised morphological and functional features of the stomatognathic system. The TMJ examination carried out included mandibular movements, pain and sound symptoms. The results of the examinations were noted, counted by electronic methods and statistically analysed. From the material, two groups were selected: without TMJ symptoms (OTMJ group) and with TMJ disorders (TMJ group). TMJ disorders were evident in 67.62% of the examined persons and this was common to both age groups. In groups with TMJ disorders a significant incidence of girls was found. In groups with TMJ disorders the number of statistically significant pathological features in the stomatognathic system increased with age. TMJ disorders appeared in both age groups in various forms, separately or in combination, with different frequency. With reference to the number and kind of symptoms obtained on interview and/or on clinical examination, four degrees of intensity of TMJ disorders have been defined and their incidence discussed.
An alternative method for recording the occlusion of the edentulous patient during the construction of replacement dentures
Authors: DUTHIE N. , YEMM R.
Published: June 2007

An alternative method of recording the occlusion for the edentulous patient is described. The method is applicable to situations where replacement dentures are to be prescribed. In place of conventional record blocks, shellac‐based wax replicas of the existing dentures are used. Such record blocks facilitate both retention of satisfactory features of the existing dentures and also the incorporation of specific modifications.
The effectiveness, in vitro, of miconazole and keteconazole combined with tissue conditioners in inhibiting the growth of Candida albicans
Authors: QUINN D. M.
Published: June 2007

Two recent antifungal agents, miconazole and ketoconazole, were combined with three tissue conditioners and tested in vitro for their effects on the growth of Candida albicans. Studies for comparison were carried out using the earlier antifungal agents, amphotericin B and nystatin. Miconazole and ketoconazole were as effective as nystatin in completely inhibiting the growth of Candida albicans. The ineffectiveness of amphotericin B when combined with tissue conditioners as an antifungal agent was confirmed. (See Addendum p.181.).
Mandibular dysfunction in 10–18 year old school children as related to morphological malocclusion
Authors: LIEBERMAN M. A. , GAZIT E. , FUCHS C. , LILOS P.
Published: June 2007

An association was sought between certain morphologic characteristics of malocclusion—Angle classification, over‐bite, over‐jet, open‐bite, cross‐bite and crowding—and the presence or absence of three cardinal symptoms of mandibular dysfunction—joint sounds, joint sensitivity to palpation and muscle sensitivity—in a sample of 369 1 school children. In addition, two additional independent variables, ‘occlusa, wear’ and ‘previous orthodontic treatment’ were introduced into the statistical analysis.

Occlusal wear and abnormal overbite were the only factors found to increase significantly the presence of dysfunction symptoms.
The disc of the human temporomandibular joint: design, function and failure
Authors: OSBORN J. W.
Published: June 2007

The directions and limits of mandibular movements are controlled by muscles and nerves, and by biomechanical constraints in the dentition and the temporomandibular joints with their associated ligaments. This paper analyses biomechanical constraints in relation to shape, function, stability and dysfunction of the disc in the joint. It is argued that the dense part of the disc is modelled in response to condylar forces which compress it into the articular eminence thereby thinning its centre and squeezing out a thickened anulus around its rim. Because of a lack of congruence between the two articulating surfaces of the joint and a very low coefficient of friction, the disc is potentially squeezed off the condyle by compression forces during opening, closing and mastication. It is stabilized mainly by its anulus whose thick rim isunable to prolapse between the condyle and articular eminence. An important function of the elastic tissue behind the thick part of the disc may be, by contracting, to prevent the soft tissues behind the joint being nipped between the condyle/disc/temporal bone when the jaw is closing. The author suggests that during mastication the function of the disc is not only to spread the joint forces but also to limit the depth to which the condyle is compressed into the soft tissues covering the temporal bone and thereby allow the condyle (and disc) sufficient freedom to spin and slide over the temporal bone without distorting and damaging the surfaces. In other words, the function of the disc is to destabilize the condyle. In terms of biomechanical constraints the disc seems more liable to prolapse anteriorly than posteriorly. It prolapses when the compression forces which tend to wedge it off the condyle cannot be resisted by its thickened anulus. If the energy of compression is stored within the distorted disc and suddenly released there is an audible click.
Wear patterns of composite restorative resins in vivo; observations by scanning electron microscopy
Authors: HENGCHANG XU , TONG WANG , SHIQING SONG
Published: June 2007

In this study, the wear pattern of seven commercial composite resins, one experimental composite and one dental amalgam were investigated. These materials were separately inserted in a separation preparation cavity of the patient's mouth. After clinical service for 3, 9 and 12 months the specimens were taken out and observed by scanning electron microscopy (SEM). It was found that the softer resin matrix wore away first while the inorganic filler particles showed no signs of abrasive wear, whereafter filler particles were loosened once there was no support of the resin matrix around them.
Methodological aspects in clinical evaluation of cast restorations with colour slides
Authors: MEZGER P. R. , VAN T'HOF M. A. , LETZEL H. , ESCHEN S. , LEEMPOEL P. J. B. , SNOEK P. A. , VRIJHOEF M. A.
Published: June 2007

In a methodological investigation colour slides were used for the clinical evaluation of crowns. Four criteria, described in a criteria list or recorded by means of reference slides, were used. In assessing the clinical characteristics of crowns to a certain extent colour slides turned out to be a useful instrument. Shortcomings of the method are discussed and improvements are suggested.
The application of a duplication technique in post‐surgical Prosthodontics
Authors: ORR M. T. S.
Published: June 2007

In the management of patients with acquired defects of the palate, continuity between immediate and intermediate stages of obturation has always posed a major problem. This is because the intermediate obturatior is required as early in the post‐surgical phase as possible, consistent with minimum interference to the healing tissues and minimum trauma to the patient. This paper describes a technique, which helps to overcome the problem.
A retrospective analysis of the treatment of occlusal disharmony by selective grinding
Authors: WINSTANLEY R. B.
Published: June 2007

The method of treatment by the author of twenty patients with the signs and symptoms of occlusal disharmony over a 2 year period are described. The majority of patients attending for recall had partial or complete resolution of symptoms. The number of patients treated was insufficient for any definite conclusions to be reached concerning this method of treatment, although it was observed that loss of first molar teeth and the presence of third molar teeth in a number of patients could be aetiological factors.
Occlusal force pattern during chewing and biting in dentitions restored with fixed bridges of cross‐arch extension
Authors: LUNDGREN D. , LAURELL L.
Published: June 2007

The pattern of axially (perpendicular to the occlusal plane) directed occlusal forces developed during light tooth tapping in habitual occlusion, chewing, swallowing and maximal biting was studied in twelve subjects whose dentitions were periodontally treated and prosthetically restored with cross‐arch bridges with unilateral posterior two‐unit cantilevers.

The measuring devices consisted of four strain‐gauge transducers uniformly and bilaterally mounted in pontics of maxillary bridges to represent the posterior (end abutment and distal cantilever respectively) and anterior regions. Thus, the forces could be studied locally in various parts of the dentition simultaneously as well as totally over the entire dentition.

The results demonstrated that the distal cantilever unit, on average, was subjected to forces about or less than half of those over the contralateral end abutment unit irrespective of the activity studied. Furthermore, the cantilever forces either equalled or were even significantly smaller than those of the anterior regions.

All subjects preferred the end abutment side as the chewing side. When the cantilever side was used as the chewing side, which occurred most infrequently, the bolus was usually located in the anterior region.

The mean total chewing force (about 50 N) was only about half of that found in a previous study of subjects supplied with cross‐arch bridges with bilateral end abutments (Lundgren & Laurell, 1985). Furthermore, on average only 26% of the voluntary muscular capacity was used during chewing, compared with 37% in the ‘bilateral end abutment group’ referred to.

The reasons for the comparably small forces over the distal cantilever unit and the lower muscular utilization during chewing in cross‐arch bridges with unilateral posterior two‐unit cantilevers as well as the implications of the findings for the dimension of such bridge constructions are discussed.
Factor analysis of dental erosion occurrence
Authors: XHONGA‐OJA F. A. , VALDMANIS S.
Published: June 2007

Some hundreds of patients in the dental schools of Los Angeles and Boston were evaluated and compared for personal information, dietary habits, oral condition and general health.

The statistical analysis of results indicated very significant differences for some variables, while others exhibited very similar values for both cities.
Laboratory studies of visible‐light cured fissure sealants: setting times and depth of polymerization
Authors: STRANG R. , CUMMINGS A. , STEPHEN K. W.
Published: June 2007

Measurements were made, using an acoustic transmission method, of the setting times of three visible‐light curing sealants (two filled, one unfilled). Five commercially available visible‐light polymerizing sources were tested with each material. Only three of the light sources gave setting times not significantly different from the manufacturers' recommended times for all three materials tested.

The variation in microhardness with depth of sealant was measured to study the depth of polymerization of the sealants, all of which were adequate. The filled sealants had microhardness values greater than the unfilled sealant, at all depths studied.
Assessment of microleakage of restorative materials by a diffusion model
Authors: SHEN C. , HERRIN K.
Published: June 2007

The time‐dependent microleakage behaviour of two types of restorative materials, a microfilled composite resin and a glass ionomer, was studied. A dentine bonding agent was also included. This study was based on a diffusion model of microleakage. It was found that the initial gap sizes of the restorations increased progressively for restorations microfilled with bonding agent, microfilled alone, and glass ionomers, in that order. Analysis of microleakage over some periods suggests that the gap size of the restorations by microfilled with bonding agent may increase with time, and that while restorations by glass ionomer and microfilled composite resin decrease in gap sizes with time, glass ionomer restorations show a faster rate of decrease.
Heat treatment, microstructure and corrosion of a low‐gold casting alloy
Authors: STRUB J. R. , EYER C. S. , SARKAR N. K.
Published: June 2007

The aim of this study was to understand the relationship between heat treatment, microstructure and corrosion of a low‐gold casting alloy. Potentiostatic and potentiodynamic polarization techniques were used to evaluate the chloride corrosion resistance of the alloy in the following conditions: (A) as cast, (B) bench cooled, (C) homogenized, (D) homogenized and aged for 2 h, and (E) homogenized and aged for 4 h.

The microstructure of each sample, before and after corrosion, was examined by optical and/or scanning electron microscopy. In general, heterogeneous structures containing dendritic segregations and precipitates were found to be more prone to corrosion than the single phase solid solution structure produced by homogenization. On the basis of the potentiodynamic polarization data, the samples were ranked as follows: C>D>B>A>E, C being the most corrosion resistant structure.
Subjective, clinical and EMG effects of biofeedback and splint treatment
Authors: HIJZEN T. H. , SLANGEN J. L. , VAN HOUWELIGEN H. C.
Published: June 2007

Patients suffering from myofascial pain dysfunction (MPD) were trained to maintain constant levels of EMG masseter activity with the aid of biofeedback. Treatment effects were compared with the effects of a nightly full‐coverage splint and with a no‐treatment control group. The biofeedback group showed significantly more improvement in clinical dysfunction and subjective symptoms related to pain and mandibular movement than either the splint group or the control group. The results of the splint group were not substantially different from the control group. The EMG results indicate that during biofeedback the ratio between EMG activity of the trained and the non‐trained masseter shifted towards a higher contribution of the trained muscle. This effect was significant at high task levels. During biofeedback EMG task performance improved but this effect did not generalize to non‐feedback situations. It is suggested that the treatment effects of biofeedback depend upon the increase in perceived control reported by the biofeedback group.
Effects of experimental loss of teeth on the temporomandibular joint
Authors: CHRISTENSEN L. V. , ZIEBERT G. J.
Published: June 2007

A review is presented of the effects of loss of teeth, with impaired occlusal stabilization, on the temporomandibular joint in experimental animals. Loss of teeth, with subsequent abnormal loading of the temporomandibular joint, leads to histomorphological, pathological and pathophysiological changes in the articular cartilages, the articular disc, the synovium, and the bony articular components. The severity of the changes increases with increasing age, and an existing arthritis of the joint is aggravated by impaired occlusal stabilization. The experimentally induced changes resemble those in human subjects with extensive loss or extensive attrition of teeth.
Dentine hypersensitivity: effect of interactions between metal salts, fluoride and chlorhexidine on the uptake by dentine
Authors: ADDY M. , DOWELL P.
Published: June 2007

A large number of compounds may be applied to the teeth for preventive or therapeutic purposes, most notably in dentine hypersensitivity. The uptake of any one compound by tooth substances may clearly be affected by another to produce synergistic, additive or antagonistic effects. This study determined whether uptake interactions occurred between fluoride, chlorhexidine, strontium, tin and zinc. All compounds, in particular tin, showed considerable affinity for dentine. Fluoride reduced the uptake of zinc but not tin, strontium or chlorhexidine. Chlorhexidine increased the uptake of zinc, but not tin, strontium or fluoride. Zinc and tin decreased fluoride uptake but strontium had no such effect. Finally, chlorhexidine uptake was increased by zinc and tin but not by fluoride or strontium. Based on the theories proposed for the reaction of these various compounds with calcified tissues, explanations for the interactions can be made. The results appear relevant to some reported clinical effects of combinations of these compounds and indicate that such interactions may have advantageous or disadvantageous consequences depending on the basis for treatment.
Physiology and pathophysiology of skeletal muscle contractions
Authors: CHRISTENSEN L. V.
Published: June 2007

An overview is presented of the physiology and pathophysiology of dynamic skeletal muscle contractions in the intact living organism. Dynamic muscle activities are divided into concentric contractions with shortening of muscle fibres and the production of positive work, and eccentric contractions with lengthening of muscle fibres and the production of negative work. In positive work, muscle tension overcomes external forces. In negative work, external forces overcome muscle tension. The latter phenomenon, with relatively few active motor units, explains the injuries induced by eccentric contractions. Both the contractile and non‐contractile elements are involved in the muscle injuries and, clinically, they are referred to as myofibrositis.
Current concepts in the aetiology, diagnosis and treatment of TMJ and muscle dysfunction
Authors: ASH M. M.
Published: June 2007

The complexity of managing TMJ and muscle dysfunction is reflected in the variety of treatment modalities that are continually being advocated. The multidimensional nature of the problem is readily appreciated in a TMJ Oral‐Facial Pain Clinic where most of the referred patients represent a broad spectrum of treatments that have failed. Where such a clinic has been present for several decades the introduction of new ideas, or the reintroduction of old forms of treatment, are readily seen as well as the quantity and quality of treatment successes and failures. A major shift in ideas concerning the natural history of TMJ/muscle dysfunction, and an explosion of treatment problems and failures related to mandibular repositioning appliances and surgery suggest the need to reconsider various approaches to the diagnosis and treatment of TMJ and muscle dysfunction. Guidelines for diagnosis and treatment of these disorders are discussed.
Changes in bite force and chewing efficiency after denture treatment in edentulous patients with denture adaptation difficulties
Authors: LUNDQUIST L. W. , CARLSSON G. E. , HEDEGÅRD B.
Published: June 2007

Masticatory function was studied by means of a chewing efficiency test and bite forces measurements in forty‐nine edentulous patients who had applied for treatment with fixed protheses on osseointegrated dental implants. Registrations were performed with the original complete dentures and after treatment aiming at optimizing the dentures. The patients were divided into two groups and the post‐treatment recordings were completed after adaptation periods of 2 and 6 months, respectively. The functional tests showed mainly small and non‐significant changes after the denture treatment. Improvement was greater, however, in those with the poorest pre‐treatment values. Chewing efficiency deteriorated after treatment in the older patients (more than 50 years) while it did not change in the younger ones. A longer adaptation period did not lead to better functional results. The findings are discussed in relation to the fact that the patients were waiting for implant treatment, with consequent psychological implications for interpretation.
The early bacterial colonization of acrylic palates in man
Authors: MORRIS I. J. , WADE W. G. , ALDRED M. J. , WALKER D. M.
Published: June 2007

Adhesive tape applied to the fitting surface was used to study the early colonization of acrylic palates in six subjects. Streptococci were major constituents of the plaque accumulated on the tape over the first 3 days.

Bacterial colonization of the tape discs was selective in that dextran‐producing streptococci constituted a greater proportion of the total streptococcal count after 15 min compared with that of the initial sample and saliva, while the converse was true for Streptococcus salivarius. Scanning electron microscopy showed that denture plaque development started in grooves and depressions on the surface of the tape, and became more extensive with time. Comparison of the colonization of tape and acrylic discs in one individual demonstrated that the tape was a suitable model for in vivo colonization of dentures or orthodontic appliances.
A ten‐year follow‐up study of alveolar bone loss influenced by two dissimilar Class II amalgam restorations
Authors: MARKITZIU A.
Published: June 2007

Twenty paired approximal amalgam restorations (E*) extended and unextended (NE†) placed in twelve patients were followed up for 10 years. Measurements of the distance between the alveolar crest and (a) the apical margin of the filling (E and NE) or (b) the cementoenamel junction of the untreated control surface (C) were performed 1, 4 and 10 years following restoration placement. The bone loss associated with NE filling did not differ significantly from that of the control group and amounted to 0.4mm in 10 years.

The 10‐year cummulative bone loss adjacent to the extended restoration (E) was 1.07 mm. Bone loss associated with the E restoration was significantly higher (P<0.001) than that of the NE and control groups at every period measured. During the first 4 years the yearly bone loss of the E group was 0.14 mm and then decreased to 0.08mm during the last 6 years.
The microstructural basis of creep of γ1 in dental amalgam
Authors: SARKAR N. K. , EYER C. S.
Published: June 2007

A previous study has shown that the addition of small amounts of tin to γ1 leads to the formation of a SnHg intergranular precipitate. The purpose of this study was to determine the effect of this precipitate on the creep of γ1. Two groups of samples were investigated. Group I included a series of γ1 samples with 0, 1, 2, and 3wt% Sn fabricated by a sintering technique at 55°C and 125mN/m2 for 72 h. Group II contained the same samples as in Group I that were further annealed at 60°C for 2000 h. Annealing was carried out to allow γ1 grain growth and equilibrium distribution of Sn at grain boundaries. Creep tests were conducted according to the American Dental Association Specification 1. The microstruc‐tures of all samples were characterized by scanning electron microscopy. The creep of γ1 was found to be controlled by the intergranular precipitate when the Sn concentration was above 1%. For a specific concentration of Sn, i.e. the integranular precipitate, creep was dependent on the distribution of Sn and not on the γ1 grain size. The more nearly continuous precipitates found in annealed samples favoured higher creep.
Helkimo's indices before and after prosthetic treatment in selected series
Authors: PEKKARINEN V. , YLI‐URPO A.
Published: June 2007

The series consisted of sixty subjects selected from the patients who attended the prosthetic or restorative departments of the Institute of Dentistry at the University of Kuopio in 1978–82. All the patients had had a mutilated or reduced dental arch in the upper or lower jaw for at least 1 year. They had received no prosthetic treatment and little restorative treatment.

Helkimo's indices were registered in the first examination. After the first examination the pre‐prosthetic treatment was performed on all the patients. The second examination was after 18 months. Then Helkimo's indices were registered again. The prosthetic treatment had then been performed on thirty‐nine patients (group A). The control group consisted of nineteen patients without prosthetic treatment (group B).

The changes in Helkimo's indices were analysed statistically (Mann‐Whitney U‐test). The changes in the anamnestic index were not significant in either group while the changes in the dysfunction and occlusal index were highly significant in both groups (P<0.001).
The coefficient of swallowable composition of masticated hard‐baked soya beans
Authors: JIFFRY M. T. M.
Published: June 2007

In addition to the graphical representation of swallowable composition (SC) of masticated food, an index—the coefficient of swallowable composition (CSC)—has been proposed in this study. This index was tested using hard‐baked soya beans on various types of dentitions. The value of CSC ranged from +24 to −14 in full dentition and full denture wearers respectively.
A rationale for the management of advanced tooth wear (ATW)
Authors: WILLIAMS D. R.
Published: June 2007

An approach to the treatment of patients with significant loss of tooth tissue is presented. Alternative treatment modes are discussed and the possible outcome of treatment considered. Guidelines are offered for the management of such cases including a flow‐chart concerning the use of temporary appliances.
Mandibular border positions and their relationships with peripheral joint mobility
Authors: McCARROLL R. S. , HESSE J. R. , NAEIJE M. , YOON C. K. , HANSSON T. L.
Published: June 2007

Peripheral joint mobility was assessed in a group of fifty‐one dental students using a modification of the Carter and Wilkinson Index. Mandibular border positions were measured both actively and passively with the aid of a millimetre ruler. The purpose of the investigation was to study possible relationships between generalized joint (hyper‐)mobility and (hyper‐)mobility of the temporomandibular joints. Only a few weak correlations were found between the mandibular border position measurements (active and passive mouth opening, active and passive, left and right, laterotrusions and active protrusion) and the peripheral joint mobility measurements. Differences between the sexes were illustrated in peripheral joint mobility with females showing a greater joint mobility than males, especially when only the passively measured joints were considered. The mandibular border positions were significantly correlated with each other (P<0.05–P<0.001) for the males, but few and then only weak relationships between these measurements could be found for the females in this group. The concept of temporomandibular joint ‘end‐feel’ in relation to joint mobility is discussed.