bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of undercut placement on crown retention after thermocycling
Authors: ARCORIA C.J. , DEWALD J.P. , VITASEK B.A. , WAGNER M.J.
Published: June 2007

The aim of this study was to examine the effect of undercuts in castings and/or tooth structure on the retention of crowns luted with glass ionomer cement. After routine full‐crown preparations had been made in 48 human premolars, wax patterns were fabricated for each tooth. Retentive coves were then produced with a round bur in either the tooth structure or the wax patterns, or in both. One group of teeth and patterns did not receive any undercuts; this was the control group. Castings were made in non‐precious metal. All crowns were luted with glass ionomer cement. Half of the samples were thermocycled, and the remainder were kept at 37°C. Crowns were removed using tension (0.012 cm min−1) and the mean bond strengths calculated. The differences in retentive strengths were tested for statistical significance using anova and Scheffe's test. The presence of coves in castings and/or tooth structure significantly increased the retentive strength of castings cemented with glass ionomer, as compared with conventional crown preparations without retentive undercuts. The effect of thermocycling on the retentive strength of castings cemented with glass ionomer was not statistically significant.
Retention of denture adhesives—an in vitro study
Authors: CHEW C. L.
Published: June 2007

Denture adhesives are being used by patients to aid the retention and stability of their dentures. A number of laboratory and clinical investigations have been conducted to study the effects of such adhesives. This study describes a simple in vitro method for measurement of their retentive effect and its relation to loss of adhesive. The results show that there is a reduction in the effectiveness of adhesives, and that there is also an increase in adhesive loss, with time. There appears to be a correlation between these two properties.
Observations in the time and frequency domains of surface electromyograms of experimental brief teeth clenching in man
Authors: CHRISTENSEN L. V. , DONEGAN S. J.
Published: June 2007

Maximum voluntary teeth clenching was performed for about 1 s to study the interactions between subjective sensory‐motor events and changes in the time and frequency domains of surface electromyograms of the masseter and anterior temporalis muscle. Isometric jaw muscle contractions were examined for their speeds of contraction, the total energy content and median frequency of their power density spectra, and for the specific rate of change and the efficiency of their voluntary and involuntary activation efforts. The observations suggested that, in general, brief maximum isometric contractions were not preprogrammed, but rather were regulated by a subconscious proprioceptive feedback mechanism; the mechanism, possibly a transcortical loop, appeared to have a low gain and to be based on recruitment/decruitment of motor units.
Prosthetic treatment for speech disorders due to surgically acquired maxillary defects
Authors: YOSHIDA H. , MICHI K. , OHSAWA T.
Published: June 2007

To evaluate speech following prosthetic obturation of surgically acquired maxillary defects, the speech intelligibility of eight patients was measured preoperatively and postoperatively, with and without prostheses. Oro‐nasal separation and velopharyngeal function were also evaluated by use of a specially designed spirometer and endoscope. Following placement of maxillary obturator prostheses, four patients achieved dramatic improvement in speech intelligibility, while four patients did not. In the latter, insufficient improvement in speech intelligibility was attributed to velopharyngeal incompetence or unstable prosthesis. Two of three patients with velopharyngeal incompetence did achieve adequate improvement in speech following placement of a speech appliance in combination with maxillary obturator prostheses.
Studies related to reaction of supporting soft tissue to denture wear: the histological response of vervet monkey oral epithelium to a ‐80 mmHg vacuum
Authors: GROSSMAN E. S. , FORBES M. E.
Published: June 2007

The histological response of vervet monkey oral epithelium to a negative force similar to that experienced under dentures was investigated. Using impression trays with adherent impressions linked to a vacuum pump, the epithelia of the hard palate, attached gingiva and alveolar mucosa of 16 monkeys were subjected to a continuous vacuum of ‐80 mmHg, and then fixed by perfusion and immersion while in situ. After processing for light microscopy, sections were measured to obtain the rete peg length, supra‐papillary width, epithelial width and basal, spinous and superficial cell density 700 μm−2. Mean values and standard deviations were calculated for each measurement and, using Student's t‐test, these data were compared with results obtained for normal tissue from nine additional monkeys. The vacuum caused an increase in epithelial width in the palate and attached gingiva, and a decrease in epithelial width in the alveolar mucosa. The cell density 700 μm−2 decreased significantly in all layers of the palate, but increased in the basal layer of the attached gingiva and the basal and superficial layers of the alveolar mucosa. The alveolar mucosa within 0.5 mm of the mucogingival junction showed a variable response. This study demonstrates that a vacuum of ‐80 mmHg modifies the structure of the oral epithelium, and this response is directly related to the functional demands of the tissue.
Comparison of food particle distribution masticated by subjects wearing complete dentures and with natural teeth
Authors: CHONG‐SHAN SHI , GUAN OUYANG , TIAN‐WEN GUO
Published: June 2007

The sizes of soya particles masticated by 12 complete denture wearers and 10 subjects with natural dentition were directly measured by means of a graphic digitizer and computer, following a varied number of chewing strokes. It was found that the chewed particle size frequency distributions of the two groups tended to a state of normal logarithm distribution. Compared with the dentate subjects, the mean, 20th, 50th and 80th percentile of the particle sizes chewed by complete denture wearers were increased, whilst the distribution shapes were nearly identical. The results suggest that there are no qualitative differences in the manner in which the two groups break up food. Selection and breakage functions of complete denture wearers are decreased, and this could be related to the denture conditions and the change of oral state in such individuals.
Observations on the motor control of brief teeth clenching in man
Authors: CHRISTENSEN L.V. , CARR A.B. , DONEGAN S.J. , ZIEBERT G.J.
Published: June 2007

Without artificial feedback control, maximum voluntary isometric contractions were performed for about 1 s by six subjects. Randomly selected surface electromyograms of the anterior temporalis and masseter muscles suggested that, in some cases, the motor control of the entire isometric contraction might have been preprogrammed through the phenomenon of anticipation. In the majority of cases, the control of the initial contraction phase might have been preprogrammed, followed by a phase of servo‐controlled motor activity. As a functional basis for the servo‐control of isometric force generation, it was suggested that compartmentalized ‘extrafusal and intrafusal motor units’ were recruited and decruited in an orderly manner, and periods of alphamotor inhibition were interpreted as signs of switching from one control scheme to another, possibly via a transcortical loop.
Force‐related changes in the masseter muscle reflex response to tooth‐taps in man
Authors: BJØRNLAND T. , BRODIN P. , AARS H.
Published: June 2007

In 14 subjects with no disorder of the masticatory apparatus, excitatory and inhibitory reflex responses in the masseter muscles were derived by standardized mechanical stimulation of the upper central incisor. A series of eight taps was delivered during isometric contraction at 40% of maximum EMG activity, with tapping forces ranging from 0.25–9 N. The mean post‐stimulus masseteric EMG complex (PSEC) consisted of up to three inhibitory (I‐1, I‐2 and I‐3) and three excitatory phases. The first inhibitory wave increased in duration with increasing tapping force, and the second and third inhibitory waves occurred at higher thresholds than the first inhibitory wave.
Masseteric post‐stimulus EMG complex following mechanical stimulation of osseointegrated oral implants
Authors: BONTE B. , van STEENBERGHE D.
Published: June 2007

Periodontal receptors can be located in the periodontal ligament itself, the alveolar bone, the periosteum and the gingiva. The aim of the present study was to quantify the contribution of the periodontal ligament receptors in eliciting a reflex response in human masseter muscles. Surface EMG recrordings were made in 17 human subjects, fully or partially edentulous, and all provided with osseointegrated oral implants ad modum Brånemark. They maintained a constant clenching level. Mechanical stimulation of an oral implant in the upper central incisor region failed to elicit a reflex in fully edentulous subjects with oral implants in both jaws. The absence of a reflex response strongly suggests that the receptors in the periodontal ligament itself are mainly responsible for the reflex. Stimulation of the same area in subjects with oral implants in the upper jaw and natural teeth in the lower jaw clicited a reflex response in most subjects. Since they were instructed to clench in full habitual occlusion, transmission from the stimulated area to periodontal receptors of natural teeth is very probable.
Influnece of an occlusal splint on integrated electromyography of the masseter muscles
Authors: SHAN SHI CHONG , YUN WANG HUI
Published: June 2007

In order to examine the effect of an occlusal splint on the integrated electromyography (EMG) of the masticatory muscles, EMG of bilateral masseter muscles of 23 patients with temporomandibular joint distrubance syndrome (TMJDS), with and without an occlusal spint, was measured and integrated on line during maximum clenching. It was found that the integrated myoelectrical value of the masseter muscle on the involved and non‐involved side was reduced with the occlusal splint. The absolute difference between integrated myoelectrical values in the left and right masseter muscles was reduced with an occlusal spint, but the relative difference remained virtually unchanged. These results indicate that the occlusal splint can decrease masseter muscle activity and thus exert a therapeutic effect.
Causes and signs of temporomandibular joint pain and dysfunction: an electromyographical investigation
Authors: SCHROEDER H. , SIEGMUND H. , SANTIBÁÑEZ‐H G. , KLUGE A.
Published: June 2007

The spontaneous muscular activity of the masseter and two non‐masticatory muscles, and their activity under conditions of noise and flickering light, were recorded in 30 patients with mandibular dysfunction, and in 25 control subjects. The mood of the subjects during the investigation, and the possible presence of emotional disturbances was evaluated by means of questionnaires. The enhanced muscular activity of the masseter muscle differentiated patients from the control group, although it does not constitute a pathognomic sign. Unilaterality of complaints, and dysfunctions of differing intensity were not reflected in differential EMG findings. One‐fifty of the patients exhibited neck muscle activity occurring simultaneously with the masseter activity. The effect of the applied stimuli on the muscular activity was not homogeneous, leading to activation in some cases and inhibition in others. Symptoms of anxiety could be observed in seven TMJ patients. Anxious patients showed higher levels of muscular activity and emotional irritability during the experiment than non‐anxious patients.
Reproducibility of electromyographic measures: a statistical analysis
Authors: FERRARIO V.F. , SFORZA C. , D'ADDONA A. , MIANI A.
Published: June 2007

The masseter, temporalis anterior and digastric anterior muscles of five volunteers have been investigated by means of surface electromyography. Each muscle was tested by three operators at different times and under three distinct conditions of intermaxillary relationship: resting, with no occlusal contact (physiological rest position); occlusion in centric occlusion (C.O.) without clenching force; and maximum voluntary clench. In all the trials the BIO‐PAK system (Bio‐Research Associates Inc., Milwaukee, WI, USA) was used. Measurements were made in two consecutive experimental trials separated by an interval of about 15 days. In the first trial the operators had minimal instrumental experience. while in the second trial the same operators had performed at least 30 measurements each. The data have been analysed by a factorial variance analysis, particularly with a view to comparing the variability between operators for each volunteer subject. The analysis revealed statistically significant differences only in the first experimental trial, due to the operators' lack of experience. The study demonstrates that the electromyographic system and protocol used allow good reproducibility of measurements. Furthermore, they have potential applications in both clinics and research.
Defects in automixed addition silicone elastomers prepared by putty‐wash impression technique
Authors: SOH G. , CHONG Y.H.
Published: June 2007

Voids presenting in impressions of five automixed addition silicone elastomers were investigated. Impressions were prepared with the putty‐light body impression technique on stainless‐steel cylinders with acrylic spacers. The number of voids was counted at a predetermined site on three separate days using a stereomicroscope at x7 magnification. Impression specimens of a hand‐mixed addition silicone, and from hand‐mixing of the automixed materials, were made for comparison. Express gave a significantly higher number of voids than other automixed materials, with President Jet having the lowest void count. Automixed materials generally produced impressions with significantly fewer voids than the hand‐mixed material. Automixing was effective in reducing void defects in elastomeric impressions.
Age and maintenance of removable dentures in Finland
Authors: MURTOMAA H. , KÖNÖNEN M. , LAINE P.
Published: June 2007

The age and maintenance of dentures, and denture‐cleaning habits, were studied by an interview survey. The material represented nation‐wide the Finnish population aged ≥ 15 years old, and there were 957 interviewees, of whom 328 were denture wearers. In total, 45% of the upper and 40% of the lower dentures were over 10 years old. More than one‐third of the dentures more than 5 years old had never been maintained during that time. Individuals whose dentures had been made and fitted by dental technicians visited dentists less frequently than individuals whose dentures had been made by dentists. Over 80% of the denture wearers reported cleaning their dentures by brushing at least once a day, and women cleaned them more frequently than men. The present findings suggest that denture wearers should be a special target group for dental health education, for the development of the latter, and for the development of dental health care services in the future.
Surface electromyographic estimates of recruitment/rate coding of masseteric motor units
Authors: DONEGAN S.J. , CHRISTENSEN L.V. , KALTENBRUNNER A. M. G.
Published: June 2007

Surface electromyographic (EMG) recordings were obtained from the masseter muscles in healthy subjects performing brisk maximum voluntary teeth clenching (MVC) for about 1s. During the onset (0–600 ms) of ballistic MVC activity, the peak amplitude of the EMG interference patterns showed a consistent and significant increase, on examination for 0–200 ms, 200–400 ms, and 400–600 ms of MVC activity. The peak (maximum) and median (centroid) frequencies of power spectrum density functions of the raw surface EMGs (interference patterns) showed an absence of consistent and significant changes during 0–600 ms of ballistic MVC activity. However, the estimated total energy contents (peak amplitude × peak frequency) of the surface interference patterns showed a consistent and significant increase from 0 to 600 ms of ballistic MVC activity, and this was interpreted as global recruitment/rate coding of masseteric motor units.
Number and intensity of occlusal contacts following surgical correction of mandibular prognathism
Authors: ATHANASIOU A.E.
Published: June 2007

The aim of the present investigation was to study the changes in the number and intensity of occlusal tooth contacts in the intercuspal position following surgical correction of mandibular prognathism. The study sample consisted of 33 adults with mandibular prognathism whose management included bilateral vertical ramus set‐back osteotomy and combined orthodontic treatment. Measurement of the number and intensity of occlusal tooth contacts was performed by means of the photocclusion technique. Recordings of the number and intensity of occlusal contacts were made 1 day before operation and 6 months post‐surgery. Testing of the differences of the means for both the number of occlusal contacts and their intensity between the two phases was achieved by means of a paired t‐test. The results of the study showed that the combined orthodontic and surgical treatment produced a significant increase (P < 0.001) in the number and intensity of occlusal contacts (4.54 and 160 kg mm−2 respectively). However, whether this increase in occlusal contacts resulted in an overall improvement in craniomandibular functional status cannot be answered by the present study.
Reinforcement of acrylic resin denture base material with metal or fibre strengtheners
Authors: VALLITTU P. K. , LASSILA V. P.
Published: June 2007

The effect of different metal and fibre strengtheners on the fracture resistance of polymethylmethacrylate was tested. Different types of commonly used metal wire and glass fibre, as well as carbon and aramid fibres, were used as strengtheners in test specimens. There were 21 groups, and each group contained 12 test specimens. Each metal strengthener had a beneficial effect on the fracture resistance of the polymethylmethacrylate (P<0.001–0.01). Some fibres, which were silanized for better adhesion, also had strengthening properties.
The clinical performance of a posterior composite resin restorative material, Heliomolar R.O.®: 3‐year report
Authors: KNIBBS P.J. , SMART E.R.
Published: June 2007

A posterior composite resin restorative material was evaluated over a 3‐year period by means of a controlled clinical trial. A total of 52 composite resin restorations and 52 amalgam alloy restorations were included in this trial, and were examined with regard to marginal integrity, surface texture, anatomical form and proximal contact with adjacent teeth. There were no significant differences in clinical performance between test and control materials, which both gave good service over the period of evaluation. Only five restorations (one of amalgam and four of composite resin) failed during the trial. Plastic replica dies were used to support the clinical examinations of the restorations, and such dies were found to be helpful.
Digital imaging techniques for dental alloy castability quantification
Authors: COHEN S.M. , VAIDYANATHAN T.K. , TANABE N.
Published: June 2007

In this study, mesh monitors cast from experimental compositions of a Ni‐Cr‐Be alloy are evaluated by the application of image analysis techniques. Castability values obtained by this method are then contrasted with those from three commonly employed manual counting procedures. While castability values obtained by all methods reflect the effect of compositional variations, a comparison of results with respect to evaluation method indicates that the image analysis technique consistently yields higher castability values, especially evident in the poorly casting groups. The apparent explanation for these observed differences is that with imaging, segments that are partially cast to varying degrees are not arbitrarily eliminated from the data, as is the usual practice in manual counting methods; therefore, castability values obtained by using the imaging technique will very closely reflect an actual alloy volume of each cast monitor.
Microleakage of indirect inlays placed on different kinds of glass ionomer cement linings
Authors: KARAAǦACLIOǦLU L. , ZAIMOǦLU A. , AKÖREN A.C.
Published: June 2007

The objective of this study is to compare the marginal seal of Class II cavities restored with indirect inlays constructed on glass ionomer cement linings having different curing properties. Also the effect of acid‐etching of these liners on microleakage was investigated.

Mesio‐occlusal and disto‐occlusal cavities in 80 extracted human molars having the cervical floor below the cementoenamel junction were prepared (n:160). Half of the preparations were restored with Ceramco II® porcelain and the rest with SR‐Isosit® resin inlay material. Liners as light curing lonoseal® light+chemically curing LCL 8® and Zionomer® and chemically curing Ketac‐Bond® glass ionomer cements (GICs) were used. On mesial preparations GICs were acid‐etched but were not on distal preparations. All inlays were cemented with Ultrabond® composite material. After thermocycling the teeth were placed in a basic fuchsin dye solution for 24h, then each tooth was sectioned. By using a stereomicroscope the extent of marginal leakage was scored and statistically evaluated.

Microleakage was observed beneath all GIC linings and was more extensive between light curing GIC/dentine interface. By acid‐etching of GICs the microleakage between GIC/dentine interface was increased significantly. Whether acid‐etching was applied or not a significantly increased microleakage was recorded between chemically curing GIC/composite interfaces. Although the marginal microleakage was witnessed in both inlays, it appeared that porcelain inlays provided a better marginal seal, in comparison to SR‐Isosit inlays.
Physics and the sounds produced by the temporomandibular joints. Part I
Authors: CHRISTENSEN L. V.
Published: June 2007

In clinical dentistry, the sounds (clicking) and noises (grating) produced by the temporomandibular joints (TMJ) usually signify dysfunction or disease of the mandibular locomotor system. In an attempt to provide guidance to the general practitioner, this article discusses some pertinent parameters defining the physics of airborne and solidborne vibrations.
Physics and the sounds produced by the temporomandibular joints. Part II
Authors: CHRISTENSEN L.V.
Published: June 2007

In clinical dentistry, the solidborne vibrations (tissue pressure waves) produced by the temporomandibular joints (TMJ) may signify dysfunction or disease of the mandibular locomotor system. This article discusses aspects of the applied mathematics and electronic recording of solidborne vibrations of the TMJ (electrovibratography).
Contribution of the mucosal tactile information to the mandibular position sense in paticnts wearing dentures
Authors: Munakata Y. , Kasai S.
Published: June 2007

The effects of mechanicals stimulation of denture‐bearing mueosa on the perception of mandibular position was tested in five patients wearing dentures. In order to produce mucosal stimulation of different intensities, five types of a punctate stimulus plate each having a different number of raised points was used. A hydraulic vertical displacement meter was also used so as to vary mandibular position. The mandibular position sense altered with changes in the physical stimulus intensity to the denturebearing mucosa within a limit of jaw separation (less than 2.3 mm). In addition, the increases of the stimulus intensities stabilized the response regarding the mandibular position discrimination. From these results, it has been suggested that the tactile information from the denture‐bearing mucosa regulates the neural mechanism concerning the mandibulr position discrimination.
Influence of lower lip support on recording of vertical dimension in edentulous patients
Authors: EKFELDT A. , KARLSSON S.
Published: June 2007

The purpose of this investigation was to assess the influence of differences in design of the occlusion rim on recorded vertical dimension in complete denture therapy. Edentulous patients were studied with an opto‐electronic method when the vertical dimension of rest was established with and without labial support of the occlusion rim. As no significant differences were found, the results did not support the hypothesis that the contour of the lip support will influence the recorded physiological rest position. However, a significant difference between intra and extraoral placement of the point of measurement was found.
The effect of time of trimming on the surface finish of anterior composite resins
Authors: HEATH J.R. , JORDAN J.H. , WATTS D.C.
Published: June 2007

This in vitro study investigates whether the surface smoothness of a finished composite resin is a function of the time at which it is trimmed. Five materials were studied. Visiodispers® (VIS) is a sintered microfine, the remainder were hybrid formulations: Miradapt® (MIR), Command Ultrafine® (COM) and two experimental formulations –‘EXP (2)’and‘EXP (15)’– with larger filler particles. All except MIR were photoactivated. Samples were placed and cured in holes machined in Perspex rods, ensuring excess of material and moulded to shape with cellulose acetate matrix strip. The strips were removed immediately after light curing and after 5 min in the case of MIR. Sample groups were finished after the following intervals: 10, 15, 30, 45 s, 1, 2, 3, 4, 5min, dry, and after 1 and 7 days in 37°C water. The finishing procedure used plain‐cut tungsten‐carbide burs and coarse, medium and fine finishing discs, which were applied for standardized times, directions and pressures. Surface roughness was assessed visually and with a surface profilling instrument. COM and VIS materials significantly improved in surface finish when the procedure was delayed for 7 days. However, EXP (2), EXP (15) and MIR surface finishes were independent of finishing time. This may result from a rapid attainment of optimum surface hardness, whereas with COM and VIS incomplete curing leads to smearing of resins and filler across the surface.
Effect of dental metals on magnetic resonance imaging (MRI)
Authors: MASUMI S. , ARITA M. , MORIKAWA M. , TOYODA S.
Published: June 2007

The aim of this research was to examine the effects of metals used in dentistry upon magnetic resonance imaging (MRI). Ten disk‐shaped samples of metals have been used in this study. Each sample has been set into a volunteer who had produced a normal MR image when tested. The subject was imaged in the sagittal, frontal and coronal plane with a 0.1T MRI device and results examined for MR defects.

Au, Ag, Au‐Ag‐Pd and amalgam produced no defect. Ni‐Cr, Co‐Cr and SUS304 expressed small amounts of MR defects, but SUS405, Pd‐Co‐Ni and Sm‐Co expressed large defects. Those metals which create MR image degradation must not be used for fixed prosthesis or orthodontic devices both of which could easily be made from other metals. If the MR image degrading metals are to be used in dentistry, their application should be restricted to removable prosthesis.
Initial flow of tissue conditioners — influence of composition and structure on gelation
Authors: MURATA H. , IWANAGA H. , SHIGETO N. , HAMADA T.
Published: June 2007

The effects of the molecular weight of polymer powders, the ethyl alcohol content of the liquids, the type of plasticizer and the polymer powder/liquid ratio on viscoelastic properties during gelation of tissue conditioners were studied with an oscillating rheometer. The results showed that:

 The gelation time decreased exponentially with increases in molecular weight of the polymer powder and with powder/liquid ratio. There were linear relationships between the log of gelation time, and both the molecular weight of the polymer powder and the powder/liquid ratio.

 In general, gelation time decreased exponentially with increases in ethyl alcohol content. However, the relationship between the log of the gelation time and ethyl alcohol content fitted a second‐order polynomial.

 The type of plasticizer affected gelation time. The order of gelation times was: benzyl benzoate < dibutyl phthalate < butyl phthalyl butyl glycolate.

The initial flow of tissue conditioners could be controlled over a wide range by varying the molecular weight of the polymer powders, the ethyl alcohol content, the powder/liquid ratio and the type of plasticizer.
An investigation into the quality of dentine bonding systems for accomplishing a durable bond
Authors: DAVIDSON C.L. , ABDALLA A.I. , DE GEE A.J.
Published: June 2007

For a wide variety of dentine bonding systems the bond strength before and after thermocycling was determined on dentine with and without hydraulic tubular pressure. The importance of the hydrophillic nature of several bonding systems could be demonstrated. The dentine smear layer could not prevent a negative effect of water in the tubulus on hydrophobic systems. Removal of the smear layer had a positive effect on the durability of the bond. When loaded until fracture, some bonding systems resisted adhesive failure.
Relationship between mean power frequency and potential of human masticatory muscles at rest position and clenching
Authors: SHI C.‐S. , QUYANG G. , GUO T.‐W.
Published: June 2007

The EMG signals from left and right masseter and anterior temporal muscles of 40 healthy subjects were sampled at rest position and through gradually increased clench level to maximum voluntary contraction (MVC) at intercuspal position. A visual sense feedback of masseter muscle potential value was used for the subject to control clench level. The relationship between mean power frequency (MPF) and potential of EMG was investigated by a curvilinear regression of the second order. It was found that the relationship was of the second order logarithmic curve with maximum value of MPF. With the raising of the potential levels of EMG, the MPF increased at the lower clench levels and decreased at higher clench levels. The results indicate that controlling an identical clench level is necessary for using MPF to describe the functional state of masticatory muscles in the clinical situation.
Longitudinal study on torque transmitted from denture base to an abutment tooth of lower distal‐extension removable partial dentures with conus crown telescopic system
Authors: OGATA K. , WATANABE N.
Published: June 2007

The purpose of this study was to make a longitudinal analysis of torque transmitted to a direct abutment tooth of a lower distal‐extension removable partial dentures constructed with the conus crown telescopic system. Torque around the vertical and lateral axes of the tooth were measured during chewing of food at the time of insertion of the new dentures to about three months after. The maximal mean value of torque (Max.MT) was calculated from the peak level of all chewing strokes at the minimum of the interocclusal distance. The integration values of torque (I) and time (T) from initiation of chewing to swallowing were obtained, then the average value of torque (Ave.T) was calculated (Ave.T= I/T).

The results are summarized as follows: (a) There were no remarkable changes of Max.MT around the both axes; (b) Max.MT around the lateral axis was 7‐47 × 10‐3kgm (mean: 25X10‐3kgm) (1kgm = 9.8Nm) in the downward direction and Ave.T around the lateral axis was 6.14 × 10‐3kgmss‐1 (mean: 10 × 10‐3kgm ss‐1) in the downward direction; (c) There were marked differences of Max.MT and Ave.T around the vertical axis between subjects. Max.MT around the vertical axis was less than 24 × 10‐3 kgm and Ave. T around the vertical axis was less than 6 × 10‐3 kgm ss‐1.
Anterior digastric muscle responses to sudden unloading of the mandibular elevator muscles in younger and older adults
Authors: KARKAZIS H.C. , KOSSIONI A. , HEATH M.R. , VAN WILLIGEN J.D.
Published: June 2007

The digastric motor responses in the unloading reflex were investigated in a sample of 10 younger and eight older dentate subjects. The occurrence of the pre‐collapse digastric activity (PDA) and the reflex events (burst of activity) following the mandibular unloading (DB) were studied separately. PDA was nearly consistent in half of the subjects of both groups. DB was clearly identified in 60% of the younger subjects, but in 54.2% of the older subjects. The mean latency of DB found in the younger subjects was 32.4 ± 9.5 ms but 34.5 ± 8.8 ms in the older subjects. For the latencies found we can infer that they are related to polysynaptic pathways. Also a slight tendency for decreased frequency of occurrence and increased latencies of DB is observed in the older age group.
Acupuncture treatment of xerostomia caused by irradiation of the head and neck region: case reports
Authors: BLOM M. , DAWIDSON I. , ANGMAR‐MÅNSSON B.
Published: June 2007

Salivary flow rates were monitored in two patients, treated with acupuncture for post‐radiotherapy xerostomia. The flow rates improved after acupuncture and the effect persisted during the 2‐year observation period.
A new method for measuring nocturnal tooth contacts
Authors: YAMASHITA S. , AI M. , MIZUTANI H.
Published: June 2007

A new portable system for measuring nocturnal tooth contacts has been devised. This system was suitable for patients to take home and record tooth contacts by themselves. A micro photo sensor using optical fibres was applied to detect tooth contacts. The sensor and the target were accurately fixed to opposed molars, respectively on the same side, with removable metal attachments. Patients were instructed to set the attachment to their tooth each experimental night. In the present study, data was assembled for four or five nights in three subjects who were free of masticatory pain and dysfunction. Each subject showed an individual tooth contact pattern. It is suggested that this new system is useful and convenient for measuring nocturnal tooth contacts.
Comparison of two different silane compounds used for improving adhesion between fibres and acrylic denture base material
Authors: VALLITTU P.K.
Published: June 2007

This study was aimed at clarifying the effects of two different silane compounds on the adhesion between the different fibres and acrylic resin. The fibres used as reinforcement in the acrylic resin test specimens were glass, carbon and aramid fibres and the silane treated and untreated versions of each type of the fibres were tested. The fracture resistance of the test specimens were assessed and the fibres were studied by a scanning electron microscope (SEM) to establish the adhesion between the fibres and acrylic resin. The results showed that silanization of glass and aramid fibres enhances the adhesion between the fibres and acrylic resin. The findings were confirmed by the SEM photographs taken. The use of a scanning electron microscope proved to be useful for the investigation of the adhesive properties of the materials used.
Effects on local blood flux of acupuncture stimulation used to treat xerostomia in patients suffering from Sjögren's Syndrome
Authors: BLOM M. , LUNDEBERG T. , DAWIDSON I. , ANGMAR‐MÅNSSON B.
Published: June 2007

Twenty‐one patients with Sjögren's Syndrome were given four different kinds of acupuncture stimulation, at acupuncture points previously used to treat xerostomia. The local blood flux in the skin overlying the parotid gland was measured with laser Doppler flowmetry before, during and after the acupuncture stimulation. The results showed that the local blood flux increased significantly during and after both manual acupuncture and low‐frequency (2 Hz) electro‐acupuncture as compared with superficial acupuncture. These results indicate that acupuncture induced an increase in the local blood flux which was more pronounced for those patients who had previously reacted with increased salivary flow to acupuncture.
Clinical performance of different post and core systems ‐ results of a pilot study*
Authors: MENTINK A.G.B. , CREUGERS N.H.J. , MEEUWISSEN R. , LEEMPOEL P.J.B. , KÄYSER A.F.
Published: June 2007

During the period 1974‐1986, 112 post and core build‐ups were inserted in 74 patients. The build‐ups consisted of a metal prefabricated post (Dentatus, Unimetric or Radix) in combination with a composite core. After an average follow‐up period of 7.9 years, 14 failures (12.5%) were noticed. Eight teeth could be rerestored and six teeth had to be extracted. However, when correction was made for teeth with a bad initial prognosis and for extractions not related to the build‐up restoration, eight failures remained caused by failure of the build‐up (7.5%). The Dentatus posts seemed to increase the risk for failure.
A model to describe how ligaments may control symmetrical jaw opening movements in man
Authors: OSBORN J.W.
Published: June 2007

A mechanical model of the temporomandibular (TM) joint was converted into a computer program, with a graphic output, which tested the simultaneous effects on symmetrical jaw opening of the following three constraints: 1) the condyle could not move above the articular surface of the temporal bone; 2) the TM ligament and 3) the sphenomandibular (SN) ligament could not be stretched. Cartesian coordinates describing the ligaments and bones of six different skulls were measured and entered into the model. Although the constraints in the model allowed five different types of jaw opening movement, only one of these was physically possible for any given position of the mandible during opening. Each movement changed the geometry of the constraints. The opening movements of the condyle followed those of the hinge and kinematic axes which have been observed in studies of symmetrical jaw opening. Together with the constraint of the articular eminence, the early phase of opening was controlled by the backwardly inclined TM ligament. The late phase of opening was controlled by the forwardly inclined SN ligament. This mechanical explanation for the observed movements of the condyle is consistent with the principle that accessory ligaments have evolved around joints to reduce the need for some neuromuscular controls by replacing them with mechanical controls.
Dual cure luting composites – Part II: Clinically related properties
Authors: VAN MEERBEEK B. , INOKOSHI S. , DAVIDSON C. L. , DE GEE A.J. , LAMBRECHTS P. , BRAEM M. , VANHERLE G.
Published: June 2007

Thirteen dual cure luting composites were compared in function of film thickness, consistency, and working time by using the American National Standard/American Dental Association (ANS/ADA) specifications for zinc phosphate cement and direct filling resins. The effect of temperature and setting reaction on the film thickness was also evaluated for some representative products.

All three clinically related properties varied widely among the products investigated. A strong linear correlation was found between film thickness and consistency. This relation is supported by the temperature dependence of film thickness of dual cure luting composites. Cooling of the material increased the consistency, resulting in a larger film thickness, while heating reduced the film thickness because of the lower consistency. However, one product with a rather short working time at room temperature occasionally exhibited a dramatically enlarged film thickness after heating, probably caused by accelerated chemical polymerization. No correlation emerged between film thickness and maximum filler size or between consistency and filler weight content. Maximum filler size and filler weight content had been measured previously in Part I of this study. Scanning electron microscope (SEM) analysis of the cured film thickness samples revealed that the largest filler particles had been crushed under the heavy load pressure during film thickness measurement. The lack of correlation between consistency and filler weight content can be explained by the multifactorial determination of the consistency.

It is concluded that the great diversity in the currently available luting composites makes clear specifications with regard to the optimum composition of luting composites urgently needed. Furthermore, more adequate methods for testing the film thickness of luting composites are also required.
Relationship between craniomandibular dysfunction and malocclusion in white children with and without unpleasant life events
Authors: VANDERAS A.P.
Published: June 2007

An epidemiologic study was conducted to investigate the relationship between craniomandibular dysfunction and malocclusion in 386 children aged 6 to 10 years with and without unpleasant life events.

The results showed no statistically significant correlations between each clinical sign and each type of morphologic malocclusion in both groups. The chi‐square test, however, revealed statistically significant correlation between the pain in the temple region and posterior crossbite in the calm group but not in the not calm group. With respect to the functional malocclusion, the chi‐square test showed statistically significant correlations between interferences in the terminal hinge movement and TMJ tenderness and difficulties in opening wide. However, these correlations were found only in the calm group. When the definitional symptoms of craniomandibular dysfunction were aggregated, no statistically significant correlations were found between them and each type of malocclusion in both groups.

The results of this study showed that the correlations between malocclusion and craniomandibular dysfunction were inconsistent.
Monitoring of the discrimination threshold for interocclusal thicknesses in rehabilitated edentulous patients
Authors: PRETI G. , GASSINO G. , LOMBARDI M. , MAZZONE P.
Published: June 2007

Thirty‐seven white Caucasian subjects with unsatisfactory dentures were tested for interocclusal thickness discrimination threshold. New dentures were prepared and the test was repeated on days 1, 4 and 90 (from delivery). Eight patients whose situation was still unsatisfactory were given osseointegrated implant anchored dentures and the test repeated at the same intervals. Results were analysed statistically. Improved denture fit was found to increase interocclusal sensitivity. Decreased sensitivity during follow‐up might indicate the need to check denture fit.
Hyperalgesic change over the craniofacial area following urate crystal injection into the rabbit's temporomandibular joint
Authors: OKUDA‐AKABANE K.
Published: June 2007

The aim of this investigation was to study the characteristics of hyperalgesia and inflammatory change in the craniofacial area following the production of an acute arthritis of the temporomandibular joint (TMJ) in the rabbit. Unilateral arthritis was produced by the injection of monosodium urate (MSU) into the TMJ of the rabbits. Hyperalgesia was evaluated by the reduction in the threshold of the head‐withdrawal response to pressure stimulation, and inflammatory change was determined by the quantitative Evans‐blue test and light‐microscopic examination of histological sections. Several hours after an injection of MSU (0.15, 0.5, 1.5 mg), hyperalgesic changes were observed over not only the MSU‐administered condyle, but also over the ipsilateral masseter muscle and temporal muscle in a dose dependent manner, and lasted for more than 24 h before gradual recovery. The other craniofacial region showed no significant threshold‐reduction. Although a very intense inflammatory sign was found in the region of the MSU‐treated TMJ, a decreased or negative sign was found in the masseter muscle with a very low threshold. Local block of the TMJ using Bupivacaine® suggested that the hyperalgesic change in the masseteric region was partly due to prolonged excitation of TMJ afferents.
Changes in function of the masticatory system from 7 to 10 years of age in relation to articulatory speech disorders
Authors: PAHKALA R.
Published: June 2007

The aim of the present study was to determine changes in function of the masticatory system in children with articulatory speech disorders and in the controls by re‐examining a sample of 287 previously studied children from 7 to 10 years of age. Articulatory speech disorders were diagnosed by the same speech therapist during spontaneous speech and test words using the Remes Articulation Test. Mandibular movement capacity, occlusal interferences, slide between retruded and intercuspal positions, and signs and symptoms of the craniomandibular disorders (CMD) were recorded by a dentist.

The follow‐up results showed that mandibular movement capacity increased in almost all individuals, decreasing only in about 10% of cases. However, among children with speech disorders lateral jaw movements decreased in about 30% of subjects. During growth the prevalence of CMD increased while single signs and symptoms fluctuated. Differences between the groups for expression of CMD, mandibular movement capacity and occlusal recordings mainly levelled off. Higher constancy of subjective symptoms and retrusive interferences in children with speech disorders than in the controls supports our previous findings that, in growing individuals, different orofacial dysfunctions seem to be associated with each other.
Masseter and temporalis surface electromyography in patients wearing complete dentures comparing anterior and posterior occlusal concepts — A pilot study
Authors: GRUNERT I. , KOFLER M. , GAUSCH K. , KRONENBERG M.
Published: June 2007

The activity of jaw elevator muscles (masseter and anterior temporal muscle) was studied by surface electromyography in 17 patients wearing complete dentures with anterior‐canine guidance.

Baseline electromyography was recorded with the dentures and compared to recordings obtained with two different splints adapted to the upper denture, one providing anterior guidance leading to immediate disclusion of the posterior teeth during any jaw movement, the other providing posterior guidance buccally on the working side and lingually on the non‐working side (bilaterally balanced occlusion).

Recordings were obtained during a sequence of different jaw movements: postural position, maximal tooth contact in intercuspal position, protrusive movement of the mandible (under tooth contact) and during lateral excursions, also carried out under tooth contact.

Muscle activity was not significantly different as recorded with dentures only versus with the splints providing anterior guidance. However, a significant increase in activity was observed with bilaterally balanced occlusion.

The results of this study in edentulous people are similar to those found in patients with natural teeth.
A 6‐year follow‐up study of oral function in shortened dental arches. Part II: Craniomandibular dysfunction and oral comfort*
Authors: WITTER D.J. , DE HAAN A.F.J. , KÄYSER A.F. , VAN ROSSUM G.M.J.M.
Published: June 2007

In this clinical 6‐year follow‐up study subjects with shortened dental arches (SDA, n= 55), characterized by the absence of molar support, are compared with subjects with complete dental arches (CDA, n= 52) with respect to items concerning craniomandibular dysfunction and oral comfort. In addition, a small group of subjects with SDA and removable partial dentures in the lower jaw (SDA + RPD, n=19) is included in this study.

Oral comfort is defined using the following criteria: (i) absence of pain and distress, meaning the absence of signs and symptoms of craniomandibular dysfunction; (ii) chewing ability; and (iii) appreciation of the appearance of the dentition in relation to absent posterior teeth. Additionally, complaints about the free‐end RPD are described.

It is concluded that: (i) a SDA (consisting of 3–5 occlusal units, OU) is not a risk factor for CMD and is able to provide long‐term sufficient oral comfort; and (ii) free‐end RPD (in the lower jaw) in SDA do not prevent CMD and do not improve oral function in terms of oral comfort.