bluuebunny/crossref_metadata_2025 huggingface dataset:
Human jaw‐opening muscle responses elicited by multiple‐site electrical stimulation
Authors: YAMADA YOSHIAKI , HARAGUCHI NAOHISA , OI KUMIKO , ASH MAJOR M.
Published: June 2007

Electrical stimuli were applied to subjects' upper and/or lower gingivae around the right canines; (i) during maintained relaxation of masticatory muscles; (ii) at an active opening position; (iii) while clenching in an incisal edge‐to‐edge contact (IEC) position; and (iv) at the wide‐open position. Reflex responses of the suprahyoid and jaw‐closing muscles were obtained using surface electrodes. The electrical stimulation produced segmented reflex excitation(s) in the suprahyoid muscle and conventional reflex excitation and/or inhibition in the jaw‐closing muscles when some background activity was maintained in the muscle(s). The excitatory reflex in the suprahyoid muscle responded to multiple site electrical stimulation which was delivered on both the upper and lower jaw simultaneously rather than to single site stimulation. Also, the responses depended on the intensity of the electrical stimulation. In particular, stronger intensities resulted in longer latencies. The results support the suggestions in our previous studies with mechanical stimuli, i.e. that the human jaw‐opening reflex can be obtained only when some background activity is maintained in the jaw openers, perhaps due to low threshold afferent input, and that spatial summation may be effective for the reflex.
Etched glass ionomer liners: surface properties and interfacial profile with composite resins
Authors: PAPAGIANNOULIS L. , ELIADES G. , LEKKA M.
Published: June 2007

The purpose of this study was to assess the surface alterations induced by acid etching on two glass ionomer lining cements (Ketac Bond, G‐C lining cement) and to evaluate their interface with a composite resin (Herculite XR) following various surface treatments. The changes in the surface composition and topography of the etched liners were studied by electron microprobe and ESCA analyses. The interfacial treatments performed on the ionomer surfaces were: (i) application of a bonding resin; (ii) 20‐s acid etching and application of a bonding resin; (iii) application of a dental adhesive based on a chlorophosphate ester of BisGMA (Scotchbond LC), without acid etching. The interfacial sealing efficiency of these treatments was studied by the silver nitrate microleakage technique combined with optical and electron microscopy. According to the results the etched surfaces of both the liners present excessive porosity with glass and matrix dissolution. Significant changes in the surface chemistry of the liners were detected indicating severe degradation. The microleakage study revealed interfacial gaps and fractures in the etched samples. The best results were obtained from the non‐etched ionomer liners which were subjected to the adhesive treatment. The efficiency of acid etching as a necessary step in the ‘layered’ technique is seriously questioned.
The effect of sustained release application of chlorhexidine on salivary levels of Streptococcus mutans in partial denture wearers
Authors: ZYSKIND D. , STEINBERG D. , STABHOLZ A. , FRIEDMAN M. , SELA M. N.
Published: June 2007

The effect of a slow‐releasing dosage (SRD) coating of chlorhexidine on the salivary levels of Streptococcus mutans and on plaque index scores in patients with removable partial dentures (RPD) was tested. The SRD proved to be effective in maintaining a low level of S. mutans counts after mechanical cleaning, as compared to a baseline established during the control period. Plaque index scores were lower following the treatment and correlated with the microbiological results. Our findings indicate that a single application of sustained‐release chlorhexidine to removable partial dentures effectively maintains S. mutans levels as well as reducing the plaque score for a minimum period of 1 week.
Evaluation of the properties of a new pour denture base material utilizing a modified technique and initiator system
Authors: FRANGOU M. , HUGGETT R. , STAFFORD G. D.
Published: June 2007

A new denture base system, Provac, has been developed for complete and partial dentures, and for relining. The Provac material is methyl methacrylate, which cures with the aid of barbituric acid. In this study the physical and mechanical properties of the new resin were investigated and compared with those of a conventional autopolymerizing material (Croform) and a conventional heat polymerizing material (Trevalon).

It was found that the dimensional accuracy of Provac was better than that of the conventional heat‐curing material, Trevalon, and the denture was finished more easily and quickly. The physical and mechanical properties of Provac resin were found to be similar to those of the other two materials, and conformed to the International Specifications for denture base materials. The residual monomer levels in Provac material were always higher than the minimal obtainable values associated with conventional heat‐cured materials when these were polymerized with a terminal boil during the curing cycle.
Studies on the temporomandibular joints of an eighteenth‐century London population (Spitalfields)
Authors: WHITTAKER D. K. , JONES J. W. , EDWARDS P. W. , MOLLESON T.
Published: June 2007

The mandibular condyles and glenoid fossae of 93 adult skulls of known age at death were studied in skeletons exhumed from the crypt of Christ Church, Spitalfields, London. Antero‐posterior and mesio‐lateral dimensions were recorded, as were the shapes together with form and surface changes. In addition, the teeth present and the extent of occlusal attrition were noted.

There was sexual dimorphism in the mesio‐lateral size of the condyle, and although ante‐mortem tooth loss was higher than in previously studied Romano‐British skulls, form and surface changes of the condyle were less marked. It is concluded that tooth loss is not the main factor involved in remodelling of the condyle.
Wear of prosthodontic materials—an in vivo study
Authors: EKFELDT A. , ÖILO G.
Published: June 2007

The aim of this investigation was to study quantitative and qualitative aspects of the wear process of some prosthodontic materials in three different persons in vivo. The in vivo models combined two methods: removable double crowns and a replica technique. The wear resistance of gold (types III and IV), porcelain and a microfilled resin was studied opposing metal ceramic crowns and in one person when opposing all four materials. All three persons had earlier histories of occlusal wear of teeth and/or restorations.

The wear rate of gold and porcelain showed equal values antagonizing metal ceramic crowns in all three persons. The microfilled resin had a wear rate three or four times higher in the same situations. No significant difference in wear resistance could be found between type III and type IV gold alloys. The wear mechanism seemed to be a fatigue type in porcelain, and in gold a combined fatigue and abrasive type of wear. The microfilled resin showed mainly a fatigue type of wear but some observations indicating a tribochemical reaction were also made.
Determination of occlusal vertical dimension by means of controlled pressure against tissues supporting a complete denture
Authors: MUNAKATA Y. , KASAI S.
Published: June 2007

In order to establish the vertical dimension (VD) of a complete denture prosthesis, a new method of determining a comfortable mandibular position was tested using a recently designed hydraulic jack (hydraulic vertical displacement meter) in five edentulous patients. The device was designed so as to vary occlusal height by means of an extraoral jig connected to intra‐oral hydraulic jacks, and to distribute the bite pressure applied against the denture‐supporting tissue in approximately the same pattern as that produced by a denture with a VD preferred by the patient. The most comfortable mandibular position determined by this method coincided remarkably with the preferred VD of each patient in our study, indicating that the new device may be used to establish VD for complete denture construction.
Clinical compliance of two resilient denture liners
Authors: GRAHAM B.S. , JONES D.W. , THOMSON J.P. , JOHNSON J.A.
Published: June 2007

Although intra‐oral‐setting resilient denture liners have been used for 30 years to treat the severely resorbed residual ridges of elderly patients, their clinical physical properties are not well understood.

The effect of clinical usage on the compliance (compressibility, flexibility) of two intra‐oral‐setting resilient denture liners was measured in 10 patients, for up to 30 days. The clinical compliance of Material B (Coe‐Comfort®) was found to be significantly greater than Material A (Veltec®) for up to 14 days. At 24 h both materials had significant compliance reductions from the original 1 h measurement. These compliance reductions continued throughout the testing period. For up to 14 days of clinical usage there were no significant differences between the compliance reductions of the two materials. The study suggests that (i) Material B would provide more effective tissue conditioning of abused residual ridge mucosa than Material A; and (ii) a functional impression made with these materials should be left in the mouth for at least 24 h before the cast is poured.
The effects of an occlusal splint on the electromyographic activities of the temporal and masseter muscles during maximal clenching in patients with a habit of nocturnal bruxism and signs and symptoms of craniomandibular disorders
Authors: HOLMGREN K. , SHEIKHOLESLAM A. , RIISE C. , KOPP S.
Published: June 2007

The effects of a full arch maxillary plane occlusal splint on the level of electromyographic (EMG) activity in the anterior temporal and masseter muscles during maximal clenching were studied in 31 patients with a habit of nocturnal bruxism and signs and symptoms of craniomandibular disorders, before and after occlusal splint therapy. The results showed, before treatment, that the occlusal splint changed significantly (in 71% of patients) the level of EMG activity during maximal clenching. However, these changes were not consistent and differed between patients and even, in some patients, between muscles. After long‐term occlusal splint therapy and improvement of the signs and symptoms of craniomandibular disorders, the number of patients who had an identical level of EMG activity during maximal clenching in the intercuspal position and on the occlusal splint tended to increase. Moreover, in these patients the level of symmetry of action in pairs of muscles during maximal clenching was strong, and the splint did not change this level of symmetry.
Correlation between degree of conversion, filler concentration and mechanical properties of posterior composite resins
Authors: CHUNG K.‐H. , GREENER E. H.
Published: June 2007

The degree of conversion, filler concentration and mechanical properties of seven proprietary light‐cured posterior composite resins were investigated. The degree of conversion of composites ranged from 43.5–73.8%. The weight fraction of filler that was obtained was in the range 66.4–85.2%. The volume fraction varied from 58.2–74.2%. The mean values of the observed compressive and diametral tensile strengths ranged from 242.3–324.7 MPa and from 39.8–62.6 MPa, respectively. The Knoop hardness numbers ranged from 41.8–81.9. Significant correlations were observed between the volume fraction of filler and the diametral tensile strength (r=0.89), and between the volume fraction of filler and the Knoop hardness number (r=0.89). No correlation was found between the degree of conversion and any of the mechanical properties of the composite resins tested. Because of the positive correlations between the volume fraction of filler and the diametral tensile strength, and between the volume fraction of filler and the Knoop hardness numbers, it is concluded that the filler concentration plays a prominent role in determining the properties of contemporary posterior composite resins.
An electromyographic study of aspects of ‘deprogramming’ of human jaw muscles
Authors: DONEGAN S. J. , CARR A. B. , CHRISTENSEN L. V. , ZIEBERT G. J.
Published: June 2007

Surface electromyograms from the right and left masseter and anterior temporalis muscles were used to detect peripheral correlates of deprogramming, also known as programming and reprogramming, of jaw elevator muscles. Putative deprogramming was attempted through the clinically recommended use of a leaf gauge, placed for 15 min between the maxillary and mandibular anterior teeth and disoccluding the posterior teeth by about 2 mm. Studied contractile activities were those of postural activity (subconscious, semi‐isometric, minimal activity) and intercuspal teeth clenching (conscious, isometric, maximal activity). Use of the leaf gauge did not affect normalized postural activity (about 4%), the duration (about 900 ms) and static work efforts of clenching (about 1200 μV.s), the time to peak mean voltage of clenching (about 400 ms), and the peak mean voltage of clenching (about 300 μV). Activity and asymmetry indices showed that the studied motor innervation patterns were not changed by the leaf gauge.
Effects of lesions to the trigeminal motor nucleus on temporomandibular disc morphology
Authors: BYRD K. E. , STEIN S. T.
Published: June 2007

Stereotaxic surgery was performed on the trigeminal motor nuclei (TMNu) of 47 actively growing rats in order to test the effects of neuromuscular alterations on TMJ disc morphology. Lesioned animals received a small electrolytic lesion to their leftside TMNu, while shams had their TMNu stimulated without an actual lesion being produced. Both lesioned and sham‐lesioned animals demonstrated significant (P<0.05; P<0.01) morphological alterations of their discs 28, 56, and 84 days postoperatively. Data indicated that (i) TMNu lesions do indeed affect disc morphology, and (ii) even subtle damage to trigeminal motoneurones can influence TMJ disc morphology. It is therefore suggested that at least some TMJ disease processes have a neuromuscular basis.
Duration patterns of percussion sound in healthy and periodontally affected teeth
Authors: TAGUCHI S. , SUGITA N. , ASAZUMA Y. , HARA K.
Published: June 2007

Ten periodontally affected subjects and 10 healthy subjects were selected in order to examine the duration patterns of percussion sounds in all upper teeth, excluding the 8′s.

Probing depth, loss of attachment, tooth mobility by ‘Periotest’, bone loss and percussion sound duration via occlusal sound analyser were recorded during the pretreatment period.

The following results were obtained from the study:

the normal duration of percussion sounds ranged from 4.40–5.33 ms;

percussion sound values of periodontal patients were of longer duration than those of healthy subjects;

a close correlation between duration and other individual parameters was found in all upper teeth, with the exception of molars.
An in vitro evaluation of a prototype CFRC prefabricated post developed for the restoration of pulpless teeth
Authors: KING P. A. , SETCHELL D. J.
Published: June 2007

Carbon fibre reinforced carbon (CFRC) in the form of a prefabricated post* has recently been developed and is theoretically acceptable for consideration in an endodontic post‐retained crown system. This study compared four different types of postcore system cemented into 40 extracted anterior human teeth. The test groups consisted of CFRC posts cemented with a composite resin luting agent, and used with either a cast gold alloy core (Group B) or a composite resin core (Group C). Two existing post‐core techniques were used as controls for comparison with the CFRC groups. One control was a prefabricated wrought precious alloy post having a cast gold alloy core, and cemented with zinc phosphate cement (Group A). The other was a prefabricated stainless steel post with a composite resin core, and cemented with a composite resin luting agent (Group D). All specimens were restored with a gold alloy crown and tested to failure with an obliquely applied compressive load at 130° in an Instron using a cross‐head speed of 5 cm min−1. The results showed that post‐retained crowns using a prefabricated CFRC post exhibited properties comparable with, and in some cases better than, those of existing prefabricated posts. The mode of failure of specimens restored with a CFRC post was more favourable to the remaining tooth tissue than was that of specimens restored with a metallic post.
The effect of a change in dietary habit upon maze learning ability in rats
Authors: AKIYAMA Y. , SHIKIMORI M. , SATOV A. , MOTEGI K.
Published: June 2007

An experimental psychological study was undertaken to assess the effect of a change in dietary habit upon behavioural development, using as a laboratory animal male Wistar rats maintained on natural foods and a processed food. Forty male Wistar rats were weaned at 21 days of age and divided into two equal groups. Group 1 was fed natural food (pressed wheat, dried fish, peanuts, cabbage and soybeans) and group 2 was fed powdered food. At 68 days of age, the rats were tested in a T‐maze. The results showed that Group 1 excelled with regard to T‐maze learning.
Proximal tooth surface quality and periodontal status
Authors: YUSOF Z.
Published: June 2007

The aim of this study was to determine the periodontal status in relation to the quality of the adjacent proximal tooth surface. The gingival index (GI) and probable pocket depth (PD) were measured in 144 contra‐lateral pairs of sound vs. restored and 95 contra‐lateral pairs of sound vs. carious surfaces in 124 patients. The restorations studied were silver amalgams and tooth‐coloured filling materials, the margins of which were supragingival or level with the gingival margins. The results showed that the GI and PD were greater for both restored and carious tooth surfaces than for the contra‐lateral sound surfaces. When all the teeth were grouped together, the differences in the mean values of GI and PD were statistically significant at the P≤0.05 level. A comparison between restored and carious (non‐paired) tooth surfaces revealed higher mean values of GI and PD for the latter, which were highly significant at the P<0.001 level. Thus the present study shows that proximal tooth surface quality influences the health status of the adjacent periodontium.
Condylar movements in clicking joints before and after arthrography
Authors: ROHRER F.A. , PALLA S. , ENGELKE W.
Published: June 2007

The aim of this study was to investigate whether anaesthesia and contrast medium injection alter the biomechanics of the TMJ, thus influencing the arthrographic diagnosis in patients with anterior disc displacement with reduction.

Opening and closing movements were recorded in nine patients by means of an opto‐electronic motion recorder (Jaws 3D) before anaesthesia, after anaesthesia and after arthrography. The system computed the trajectories of a condylar point in the sagittal, frontal and horizontal plane. Data were analysed for changes in the position of the clicks, for the amount of condylar translation and for changes of the trajectories between recording conditions.

The results indicated that arthrography had a significant effect on the position of the opening clicks in all nine patients. After injection, the clicks occurred on average 1.6mm later than before injection. This was probably due to the excursive movements required for defusion of the contrast medium in the joint. The other parameters examined were not affected by the joint anaesthesia and the arthrographic procedure. The interventions influenced the shape and the incline of the sagittal condylar movement in three of the nine patients. In conclusion, arthrography altered the joint biomechanics, but not sufficiently to invalidate the arthrographic diagnosis.
Microleakage in three designs of glass ionomer under composite resin restorations
Authors: GORDON M. , WASSERSTEIN A. , GORFIL C. , IMBER S.
Published: June 2007

Three Class V cavity configurations with walls above and below the cemento‐enamel junction were compared when ‘sandwich’ technique restorations with glass ionomer and composite resin were used. No dye penetration occurred at the occlusal cavosurface margin when the latter was bevelled and light‐cured Scotchbond was applied to the ethced enamel before restoration with Durafil composite resin. The least dye penetration at the gingival margin was observed when Ketac bond glass ionomer covered the entire non‐bevelled wall. No configuration entirely eliminated dye penetration at the gingival margin.
Management and subsequent 13‐year progress of a mandibular fracture with malocclusion in a child – case report
Authors: TAMARI K. , SHIMIZU K. , MURAKAMI T. , TAKAHAMA Y. , YOKOTA S.
Published: June 2007

Under acute conditions, maxillofacial injuries may be treated without the opportunity for an assessment of occlusal irregularities, even when there are mandibular fractures, because life‐threatening injuries have priority over occlusion. Consequently, mandibular fractures may result in post‐trauma malocclusion and facial deformity.

The case history reported is of amale patient who had been involved in a traffic accident in childhood and suffered mandibular fractures. The initial incomplete man‐ agement resulted in persistent deformation of the mandible, disturbance of dental occlusion and difficulty in mastication. These irregularities were corrected during childhood by non‐operative orthodontic treatment.

When the patient reached adulthood, some permanent teeth were malformed because the fractures had damaged some tooth germs. However, the permanent dentition in general was almost normal as a result of the corrected primary dentition. Although the alveolar deformity due to the injury remained, the mandibular base was satisfactorily remodelled.

The case reported supports the view that early restoration of normal dental occlusion before the eruption of permanent teeth contributes to the establishment of good functional dental occlusion of the permanent teeth.
The prevalence of craniomandibular disorders in completely edentulous denture‐wearing subjects
Authors: MERCADO M.D.F. , FAULKNER K.D.B.
Published: June 2007

A total of 201 completely edentulous subjects taken consecutively from the waiting list of the Royal Dental Hospital of Melbourne were examined. Data were obtained from the dental history and anamnestic and clinical examinations. Analysis revealed that parafunctional habits were prevalent among complete denture wearers, and that elderly complete denture wearers potentially present more signs and symptoms of craniomandibular disorders than do younger subjects.
Comparison of amalgam behaviour under static and cyclic sub‐modulus of rupture loading
Authors: GERZINA T.M. , WING G.
Published: June 2007

The behaviour of amalgam beam specimens subjected to a sub‐modulus of rupture load at 37°C was compared in static and cyclic modes. Testing was performed using identical equipment, with cyclic testing conducted by intermittent load application for both tests. The specimens tested exhibited varying degrees of deformation and times to fracture in both tests. The mode of load application, either cyclic or static, did not appear to have a significant effect on the degree of amalgam deformation or time to fracture. The most important factors relating to deformation are time of total load application, creep of the specific amalgam and temperature of testing.
Magnesium sulphate as a new desenstizing agent
Authors: GUO‐HUA LIU , MORIMOTO M.
Published: June 2007

Various desensitizing agents have been used in clinics to solve the problem of dentinal hypersensitivity (DH), but none of them has been shown to be consistently effective. We here introduce a new type of desensitizing agent, i.e. 4% magnesium sulphate with iontophoresis at 2mA for 3 min. These optimal conditions were determined by animal experiments, while only a minor effect on dentinal issues was observed within 4 weeks after the treatment. When this desenistizing agent was used to treat DH, the cure rate of 62.4% remained steady within the 25‐week observation period, while some effect was achieved in all the subjects who participated in the study.
Effects of phosphoric acid and tannic acid on dentine collagen
Authors: OKAMOTO Y. , HEELEY J.D. , DOGON I.L. , SHINTANI H.
Published: June 2007

We examined the effects of phosphoric acid, the most common enamel etchant in composite resin therapy, on dentine collagen. Dentine collagen pretreated with 7 M phosphoric acid was shown to be more susceptible to trypsin digestion than untreated collagen. This susceptibility increased with increasing duration of exposure to the acid. The results indicate that phosphoric acid induces a conformational change in dentine collagen (denaturation or perturbation) similar to that observed with 0.39 M HCI, which has a similar pH value (0.65). However, phosphoric acid‐pretreated dentine collagen, when treated with tannic acid for 2 h, became as resistant to tryptic digestion as intact dentine collagen. The present results suggest that tannic acid may work as a dentine conditioner in composite resin therapy, in view of the fact that phosphoric acid etchant is applied, either deliberately or inadvertently, to dentine, and would thus induce denaturation or perturbation of collagen.
Palpation as a method for evaluating occlusal discrepancies
Authors: ITO Y. , RUCKER L.M. , HASHIMOTO K. , TAKEHANA S.
Published: June 2007

In this study, 30 dentists were surveyed about their methods of palpating teeth for the evaluation of premature contacts. Thirty‐eight dentists were then tested to determine their ability to discriminate degrees of prematurity using each of two different methods of palpation. The degree of digital pressure used by each dentist during palpation was also measured. The majority of dentists chose the same method for palpation: a single forefinger overlaying the facial surfaces of the central incisors being evaluated. In the discrimination test, the majority of dentists were able to identify reliably occlusal interference of ≥50 μm regardless of the palpation method used.
Prevalence of craniomandibular disorders in adults of Ilala District, Dar‐es‐Salaam, Tanzania
Authors: MAZENGO M. C. , KIRVESKARI P.
Published: June 2007

The prevalence and distribution of signs and symptoms of craniomandibular disorders (CMD) were studied in a random sample of 100 adult Tanzanians. The associations between subjective and objective findings were analysed. Signs and symptoms of CMD were assessed by interview and clinical examination. Twenty‐six per cent of subjects reported at least one symptom, and in 40% at least one clinical sign was present. No significant differences were observed between the sexes. Tenderness of the lateral pterygoid area and crepitation of the temporomandibular joint increased significantly with age. Several significant associations between subjective and objective findings were observed. The distribution of the signs and symptoms of CMD in Tanzanians was not dissimilar to that observed in the developed countries. The prevalence was not high by comparison, but sufficient to lend credence to the general view that CMD is a universal problem.
Dentine hypersensitivity – the effect of toothbrushing and dietary compounds on dentine in vitro: an SEM study
Authors: ABSI E.G. , ADDY M. , ADAMS D.
Published: June 2007

Dentine hypersensitivity occurs when dentinal tubules are open on the dentine surface and patent to a vital pulp. There has been limited interest in the aetiology of dentine hypersensitivity. In particular, little is known about agents that remove the dentine smear layer to expose tubules. Toothbrushing certainly may expose dentine, but whether a toothbrush per se has the effect of opening tubules has not been established. The aim of this study in vitro was to determine whether a toothbrush could remove or create a smear layer. In addition, the combined effects of toothbrushing with dietary fluids on dentine was assessed. Toothbrushing was observed, by scanning electron microscopy, both to remove and to recreate a smear layer on dentine specimens. However, the processes took a considerable time, and under conditions of normal toothbrushing it is unlikely that the latter plays a direct aetiological role in opening tubules. Indeed, together with toothpaste it is more likely that brushing has a therapeutic action by mechanically forming a smear layer. Conversely, and importantly, toothbrushing in the presence of dietary acids enhanced smear layer removal. This finding raises the question of whether the dental profession should be advising that teeth be brushed before meals rather than after, as is often the case.
The antimicrobial effect of an iron‐binding agent on Streptococcus mutans
Authors: BAPNA M.S. , MUKHERJEE S. , MURPHY R.
Published: June 2007

The antimicrobial activity of 2,2′‐bipyridine, an iron‐binding agent, was investigated by incorporating this agent into Scotchbond® dental adhesive resin. The growth of Streptococcus mutans on the surface of resin, media and culture vessel was determined by optical density measurements. It was observed that 2,2′‐bipyridene exhibited excellent antimicrobial properties.
Bond strength and rupture properties of some soft denture liners
Authors: SINOBAD D. , MURPHY W.M. , HUGGETT R. , BROOKS S.
Published: June 2007

The bond strength and rupture properties of three soft acrylic liners (Coe‐Soft, Coe Super‐Soft and Vertex Soft) and two silicone liners (Molloplast‐B and Flexibase) were tested immediately after processing and following immersion in water at 37°C for 7 and 90 days. The bond test gave variable results, as some materials partly peeled and then stretched until rupture occurred. After saturation the acrylic liners exhibited an increase in tear resistance, whilst silicone materials deteriorated, in the case of Flexibase to approximately 25% of its original value. Vertex Soft was the exception, as tear resistance decreased as water sorption increased. Scanning electron microscopy revealed indefinite demarcation between soft acrylic resins and hard denture base, which was not altered after saturation in water. On the other hand, the interface between denture base and silicone liners was clearly visible before and after saturation. The results indicated that denture soft liners had variable water sorption values depending on their basic structure, and some properties changed after immersion in water, a finding that is of relevance to prosthodontic practice.
The relationship of occlusion, parafunctional habits and recent life events to mandibular dysfunction in a non‐patient population
Authors: SCHIFFMAN E. L. , FRICTON J. R. , HALEY D.
Published: June 2007

This study investigated the association between occlusion, oral habits and stress relative to the level of mandibular dysfunction in the total population and in specific diagnostic subgroups (normal, joint disorder, muscle disorder and joint/muscle disorder). A total of 269 nursing students were given a questionnaire and examination. The questionnaire included items to calculate an oral habit index and a social readjustment rating scale. The examination included items to calculate an occlusal index, two craniomandibular indices and a diagnostic criteria for specific subgroups. In the total population there was a positive association between mandibular dysfunction and three postulated risk factors. The total population was then divided into diagnostic subgroups. There was a positive association between the degree of mandibular dysfunction and parafunctional habits for normals, muscle disorders and joint/muscle disorders. There was a positive association between mandibular dysfunction and occlusion for normals only. Finally there was a positive association between mandibular dysfunction and stress for muscle disorders only. The results suggest that associations between postulated aetiologic factors and mandibular dysfunction vary depending on whether the subjects have a muscle and/or joint disorder. Since all associations were weak, other possible risk factors need to be investigated.
A preliminary study of manducatory behaviour influenced by stress and dental occlusion
Authors: WESTPHAL A. , DIVRY M. , LEY I.
Published: June 2007

Stress and dental occlusion often are incriminated as causes of dysfunction of the manducatory system. How and in what degree these two factors came through has not yet been clearly worked out. Our study is carried out on a group of rats presenting one or both of these two factors and we proposed to examine the duration and frequency of some components of their behaviour – intake of solid food and grooming, to detect some possible perturbations on manducatory behaviour caused by stress and/or occlusal interference.

Our study shows that stress induced by emotion or occlusal interference will change the microstructure of behaviour rather than the global component in itself. This implies that we must find a clear definition of the different types of microstructure to find out which ones are changed by the two incriminating factors and which part of the behaviour component will remain stable.
Discrimination of clenches at varied jaw positions using autoregressive model coefficients of myoelectrical activities of anterior temporal and masseter muscles
Authors: MAO Y. , SHI C.‐S. , GUO T. W.
Published: June 2007

During 10% maximum clenching at intercuspal, protruded, retruded contact and lateral positions, the surface electromyograms (EMG) of bilateral anterior temporal and masseter muscles of 20 normal subjects with intact natural dentitions were recorded. The autoregressive (AR) model of the sampled EMG was then built and the obtained coefficients of the AR model were accepted as featured parameters of the EMG. Finally Bayes' stepwise discriminant analysis was used for establishing discriminant functions of estimating low level clenches at varied jaw positions. It was found that total conformation rates of internal and external sample substitution (15 and 5 subjects) were 82.67% and 78% respectively; the discriminant effect between intercuspal and retruded contact position was not up to predicted standard. The results indicate that AR model coefficients may describe the characteristics of surface EMG of masticatory muscles and easily be used in multiple statistical analysis, from which the classification and diagnosis may be taken.
Effect of mechanical pressure on the blood flow in human palatal mucosa measured by temperature controlled thermoelectrical method
Authors: YOSHIDA N. , MINAGI S. , SATO T. , KADOYA S. , MATSUNAGA T.
Published: June 2007

Mucosal blood flow in the human palate was measured by a temperature controlled thermoelectrical method based on the thermal conductivity of mucosal tissue using a blood flow monitor and a non‐invasive surface probe.

The effect of mechanical pressure on the palatal mucosal tissue was studied. Mechanical pressure (2.5, 5.0, 7.5, 10.0 or 15.0g mm−2) to the mucosal surface was exerted circumferentially around the surface probe. In five out of seven subjects, the blood flow showed a tendency to be almost constant under the mechanical pressures which are 10.0g mm−2 or higher. The effect of the duration of the pressure (10.0g mm−2) exertion on the blood flow was also investigated and it was revealed that the blood flow tended to be constant after 60s in every subject. In the present study, it was also demonstrated that the temperature controlled thermoelectrical method is appropriate for studying the blood flow dynamics in oral mucosa.
Observation of proportionality of myoelectrical activity of anterior temporalis to masseter muscle during clenching at varied jaw positions
Authors: SHI C.‐S. , AN Y.
Published: June 2007

Twelve healthy subjects with an intact permanent dentition and normal occlusion were selected for sampling of myoelectrical activity of their left and right anterior temporal and masseter muscles during habitual clenching level in varied positions. The proportionality of normalized myoelectrical potentials of anterior temporal muscle to masseter muscle at ICP and RCP was greater than one, while the proportionality at PP was less than one. In the lateral position, the proportionality on the working side was approximately equal to that at RCP, while the proportionality on the non‐working side was similar to that at PP. These results suggest that temporal muscle contraction can bring the mandible upward and backward whilst the masseter muscle can elevate the mandible upward and forward.
The effect of splint therapy on TMJ position measured by the Gerber Resiliency Test
Authors: DOS SANTOS J. , NOWLIN T.P.
Published: June 2007

The Gerber Resiliency Test is a clinical approach to possible evaluation of compression or distraction in the temporomandibular joints. In this study the same principle was used to check the tendency of mechanical responses of joints to the use of bite‐splints. Sequences of tests were performed on 18 adult patients of the UTHSCSA clinical pool who had been previously treated for splint therapy. From this population nine patients Presented one or more symptoms of TMD and nine were free of symptoms. Separation of the molars wih the use of one thickness of tin foil indicated tendency to compression in the joints and three or four thicknesses to distraction. The tests were performed during delivery of the appliance adn 1 week later. One sample chi‐square statistical test was performed and did not show any statistically significant difference between dysfunction and non‐dysfunction groups (P < .05) At delivery, ther was a higher frequency of distraction in both left and right joints (P < .05) when the splint was inserted. Compression was present at very low frequency. One week later, the joints did not stay distracted in the same frequency.
Hemifacial microsomia and hypodontia: a case report
Authors: ALKUMARU H. N. , CÖLOK G.
Published: June 2007

A 6‐year‐old girl with hemifacial microsomia was examined. Abnormalities found were: severely malformed pinna of the right car, right malar hypoplasia and unilateral mandibular hypoplasia. Dental examination revealce normal intraoral soft tissues with all deciduous teeth present. Radiographic examination disclosed that the maxillary and mandibular right and kleft second premolars were not devcloping. The mandibular ramus was short in leanth and the mandibular condyle had not developed on the right. The patient had no renal, cardiac or skeletal anomalies and her hearing was normal. No previous publications have been located whchreport the association of hypodontia and hemifacial microsamia.
Influence of porcelain material and composite luting resin on microleakage of porcelain laminate veneers
Authors: ZAIMOǦLU A. , KARAAǦAÇIOǦLU L. , ÜÇCTAŞLI
Published: June 2007

Summary The microleakage beneath porcelain laminate veneers was investigated. The restoration margins were located according to the preparations made below or above CEJ of extracted maxillary central incisors. Vitadur N and Microbond porcelain materials were used to prepare laminate veneers. A light cured composite resin (Porcelite®) and a light‐ and chemical‐cured composite resin (Porcelite Dual Cure®) were used as luting agents. The bonded specimens were thermocycled and by employing the standard dye penetration technique, the leakage was scored from cervical and incisal margins.

Significantly greater microleakage was recorded at the dentine composite resin interfaces than at the enamel/composite interfaces. Statistically insignificant differences were observed with the use of the four cement/porcelain combinations studied.
Effects of nickel‐chrome dental alloys used in dentistry on saliva and serum nickel levels, peripheral T‐lymphocytes and some other blood parameters
Authors: ARIKAN A.
Published: June 2007

Summary Epidemiological investigations have shown that nickel is a potent sensitivity producing agent. However, it is not known if intra‐oral use of nickel‐chrome alloys can cause any sensitization reaction.

The purpose of this study was to determine if nickel‐chrome alloys used in dentistry influence nickel levels in saliva and serum and whether there were associated changes of some blood parameters such as lymphocyte, T‐lymphocyte, neutrophil, cosinophil, basophil and monocyte.

The study was performed on 10 patients all of whom had no medical and dental history of using nickel containing drugs or restorations. Four unit fixed partial pros‐theses containing 22.97% nickel and 22.65% chrome were constructed and worn by the patients. Blood and unstimulated whole saliva samples were taken from the patients before insertion of the prostheses and then 1 month and 6 months post‐insertion. Hematocrit determinations, total and differential leucocyte count, total T‐lymphocyte counts and serum nickel concentrations were determined from the blood samples and salivary nickel concentrations from the saliva samples.

It was found that there were no significant changes in circulating T‐lymphocyte and monocyte population but a decrease was found in circulating eosinophil and an increase in circulating neutrophil and basophil populations.
Effect of metal strengthener's surface roughness on fracture resistance of acrylic denture base material
Authors: VALLITTU P.K. , LASSILA V.P.
Published: June 2007

Summary The aim of this study was to clarify the effect of the surface roughness of various metal wires on the fracture resistance of the acrylic test specimens. The number of test groups compared were 16, and there were 30 test specimens in each group. The investigation showed that the surface roughening of the metal wires used to reinforce acrylic resin denture base material increasead the fracture resistance of the test specimens. The best results were achieved by sandblasting. The differences in resistance were also statistically significant.
Frequency analysis of electromyographic signals in mandibular elevators at maximum clench level
Authors: SHI C.S. , OUYANG G. , GUO T.W.
Published: June 2007

Summary Power spectral analysis of electromyogram (ENG) was used to investigate the relationship between mean power frequency (MPF) and sustained contraction time. Surface EMG activity was recorded from masseter and anterior temporal muscles on both sides for seven healthy subjects while clenching at intercuspal position in maximum potential level of these muscles. A visual sense feedback of EMG potential was used to control clenching level. According to linear regression analysis, there was a negative correlation between MPF of EMG and sustained contraction time. The results indicate that the slope of MPF versus contraction time may be used for detecting muscular fatigue in the stomatognathic system.
Effects of ultrasonic instrumentation on microleakage in composite restorations with glass ionomer liners
Authors: ARCORIA C.J. , GONZALEZ J.P. , WITASEK B.A. , WAGNER M. J.
Published: June 2007

The aim of this study was to determine the effect of ultrasonic instrumentation on composite resin restorations lined with glass ionomer cement by measuring the extent of dye penetration at the restoration/tooth interface. Preparations, 2‐0 mm in diameter and 2‐5 mm in depth, were made with a 331 bur in 96 human molar teeth without a bevel. The teeth were restored with glass ionomer eement liners (Shofu) and one of two types of composite resin (Silux® and P‐30®). Half of the samples were ultrasonically instrumented for 10 s. The teeth were immersed in 0‐5% methylene blue dye solution and vertieally sectioned. Mieroleakage was scored visually using a seale of 0 to 4. Statistical comparisons were made with X2 analysis and the Marin‐Whitney U‐test at the F<0.05 level. Microleakage was significantly different between both resin types (P< 0‐001), and between the lined and unlined resins (P< 0‐001) that were instrumented, particularly in the P‐30® restorations. Although P‐30® restorations exhibited much less microleakage than Silux®, the use of a glass ionomer liner did not reliably reduce microleakage in either type of material after instrumentation with an ultrasonic device.
Quantification of noble alloy used in‘porcelain‐fused‐to‐metal’restorations
Authors: SOH G.
Published: June 2007

High costs of gold alloys used in metal substructures of ceramo‐metal restorations increase the cost of restorative treatment. This study determined the per unit weight of a noble metal alloy used in ceramo‐metal crowns and three‐unit fixed‐partial dentures. Generally, tooth size and extent of the tnetal substructure determined the quantity of alloy used.
A transcranial radiographic examination of the temporal portion of the temporomandibular joint
Authors: KEESLER J.T. , CHRISTENSEN L.V. , DONEGAN S.J. , AUSTIN B.P.
Published: June 2007

The temporomandibular joints of 20 human cadaver heads were examined by means of photography (gross anatomic images) and radiography (lateral oblique transcranial images), using the angle created by a line parallel to the Frankfurt horizontal and a line coinciding with the posterior slope of the most lateral (outermost) portion of the articular tubercle. This lateral eminence angle, made visible through an attached metal wire and a straight stick pin and pertaining to the outermost (zygomatic) portion of the eminentia, was about 45° on both enlarged photographs and enlarged radiographs. There were no significant differences between the photographic and radiographic lateral eminence angles on the right and left sides. A more medially placed angle, yet pertaining to the lateral — and supposedly functional (protrusion) — portion of the glenoid fossa, was about 36° on the right side and 51° on the left side of the radiographic images. There were significant differences between the ipsilateral radio‐graphic lateral and medial eminence angles. A separate decision‐making analysis concluded that lateral oblique transcranial radiography is an effective, reliable, and inexpensive method for detection of bony changes in the lateral portions of the temporomandibular joints.
The oral status of elderly removable partial denture wearers
Authors: DRAKE C. W. , BECK J. D.
Published: June 2007

A random sample of 1019 elderly home dwelling persons participated in this study. There were 809 dentate respondents, 28.6% of whom wore removable partial dentures. They were examined for coronal and root caries, gingival recession, pocket depth and loss of gingival attachment. The removable partial dentures were also evaluated. Abutment teeth were found to be more likely to have caries and periodontal disease than all other teeth. Using a manova statistical procedure, the analysis indicated that the partial denture itself, irrespective of any professionally determined problems with the denture, appears to affect coronal and root caries on the teeth of partial denture wearers. Partial dentures judged to need repair or adjustment were related to periodontal status. The data on adverse effects of partial dentures suggest a need for patient education by the dentist and through public health measures, and good oral self care and regular professional recall for people who wear removable partial dentures.
Longitudinal study on forces transmitted from denture base to retainers of lower distal‐extension removable partial dentures with conus crown telescopic system
Authors: OGATA K. , OKUNISHI M. , MIYAKE T.
Published: June 2007

The purpose of this study was to perform longitudinal measurement of forces transmitted from the denture base to retainers of lower distal‐extension removable partial dentures with a conus crown telescopic system. The experimental denture was embedded with a force‐detecting unit which could detect a change in lateral and vertical forces transmitted from denture base to retainers at the same time. Forces were measured during chewing of food on several separate occasions from the insertion of new dentures to about 3 months after. Max.ver (maximal mean value of vertical force) and Max.lat (maximal mean value of lateral force) were calculated from the peak level of all strokes of chewing of food at the minimum of the interocclusal distance.

The results are summarized as follows:

There were no significant changes of Max.ver and Max.lat;

There were no significant differences of Max.ver between subjects the value of which was about 20 N;

There were significant differences of Max.lat between subjects the value of which was less than 15 N.