bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of four different denture cushion adhesives – a subjective study
Authors: Uysal  , Altay  , Alparslan  , Bilge
Published: March 2003

Four cushion adhesives (Fittydent I; Fittydent II, introduced as an advanced formula; Protefix; and Seabond) were compared clinically through patients subjective evaluations. Maxillary dentures of 32 patients were relined and the mandibular dentures were scored by Kapur index before the application of different treatments. The cushion adhesives were used only with the existing mandibular prosthesis. The four treatments were applied to the patients in groups of 8 by allocating each group randomly to one of the four sequences of treatments determined by latin square design. Each patient took each treatment only once. The adhesives were applied by the authors as recommended by the manufacturers. Patients used each material for 24 h and, through a questionnaire, they evaluated the seven following aspects of each different cushion material: retention, duration of retention, effects on ability to chew, effects on other oral functions, cleansing of dentures, cleansing of gums, and an overall evaluation of materials. Both Fittydent products significantly improved denture retention and the ability to chew. The patients who expressed ‘much better’ chewing with Fittydent products, had mandibular dentures rated poor or fair.
Evaluation of chewing activity in the elderly person
Authors: Miura  , Araki  , Hirai  , Isogai  , Hirose  , Umenai
Published: March 2003

In the present study, we examined the chewing performance of 70 elderly persons. Self‐assessment of chewing problems and clinical classification using the modified Eichner index showed little correlation (Kappa value = 0.28; 95% confidence interval (CI) = 0.05–0.51). The sensitivity and specificity were 0.52 and 0.76, respectively. On the other hand, the mastication score determined by evaluation of a questionnaire on food intake and classification using the modified Eichner index showed high agreement (Kappa value = 0.73; 95% CI = 0.50–0.96). The sensitivity and specificity were 0.76 and 0.95, respectively. The mastication score showed significant correlation with other masticatory functions such as maximum biting force, occlusal contact area and the number of missing teeth (P < 0.01). These results suggest that the use of a questionnaire on food intake would be informative for epidemiological surveys of chewing activity in the elderly.
Detection of onset and termination of muscle activity in surface electromyograms
Authors: Abbink  , Van Der Bilt  , Van Der Glas
Published: March 2003

SUMMARY A method of automated detection of onset and termination of rhythmic muscle activity in electromyograms (EMGs) is presented. A threshold level in the EMG is computed, such that amplitudes in the EMG signal exceeding this level indicate muscle activity. The threshold level is determined using a statistical criterion based on the amplitude distribution of the entire EMG signal. The working of the method is illustrated with EMG signals recorded from chewing muscles. EMG signals with a good as well as a worse signal‐to‐noise ratio are presented. The method can be used for any EMG signal containing cyclic bursts of activity and thus may be applied in studies on rhythmic movements, such as chewing, walking and breathing. An automated method of EMG burst detection has the advantage that large amounts of EMG data can be easily and objectively processed.
The effect of the photopolymerization method on the quality of composite resin samples
Authors: Tarle  , Meniga  , Ristic  , Sutalo  , Pichler  , Davidson
Published: March 2003

An optimal degree of conversion and minimal polymerization shrinkage are generally antagonistic goals, as increased monomer conversion invariably leads to elevated polymerization shrinkage values. However, both parameters are indispensable for an optimal resin composite restoration. A number of approaches have been used to reduce the stress on the restoration cavity wall interface, such as dentine bonding agents to counteract polymerization shrinkage, stress‐absorbing lining materials and low‐intensity curing lights to control the flow capacity of the material during polymerization. However, the configuration of the cavity and cohesive fractures of the material and surrounding tooth tissues are still a problem in day‐to‐day clinical practice. A new photopolymerization light source, pulsed laser, ensures a higher degree of conversion and lower polymerization shrinkage, and differentiates this technique from standard polymerization methods and continuous‐wave argon laser polymerization. The coherence and monochromacity of pulsed laser light set at 468 nm and the far greater intensity of laser nanopulses produce a saturation effect in the depths of the composite, thus resulting in higher monomer conversion. The total amount of energy illuminating the sample surface, which is only one‐fifth of that of conventional methods, and the cooling and relaxation of the material between nanopulses may be responsible for the reduced net polymerization shrinkage.
Self‐reported symptoms of temporomandibular dysfunction in a female university student population in Saudi Arabia
Authors: Zulqarnain B. J. , Khan N. , Khattab S.
Published: March 2003

The symptoms of temporomandibular dysfunction (TMD), reported by 705 female university students of Riyadh, Saudi Arabia, are analysed. The population is representative of the educated class of Saudi Arabia. The most frequently reported symptoms were jaw feeling tired (34·5%), awareness of uncomfortable bite (31·3%), pain in front of the ear (22·4%) and discomfort upon wide opening (22·4%). The frequency of subjective reactions was, pain interferes with activity (42%), disturbed sleep (40·6%), taking of medication (27·8%) and pain being frustrating or depressing (26·8%). Some interesting relationships were found between the reported symptoms and marital status, residence and college of education. These findings are similar to those reported in a Bedouin community in Egypt, but lower than that in a Saudi Arabian population attending dental clinics, Saudi male dental students and high school students.
Relationship between mandibular position and the coordination of masseter muscle activity during sleep in humans
Authors: Minagi S. , Akamatsu Y. , Matsunaga T. , Sato T.
Published: March 2003

Although bruxism has been regarded as having a possibly important role in the aetiology of craniomandibular disorders, the activity of masticatory muscles relative to mandibular position during sleep grinding as recorded by electromyography (EMG) has not yet been clarified. Surface EMGs of the bilateral superficial masseter muscles were recorded simultaneously with mandibular position during sleep from 12 volunteers for three consecutive nights. The incidence of two mandibular positions were recorded with magnetic sensors for both left‐ and right‐sided mandibular grinding. One of the mandibular positions was the canine edge‐to‐edge position, and the other was the midpoint between the intercuspal position and the canine edge‐to‐edge position. The mode of the working/balancing activity ratio ranged from 1/10 to 2/10, showing the marked predominance of balancing side masseter muscle activity during sleep grinding. During sleep grinding, EMG bursts of masseter muscle were observed mainly with mediotrusive mandibular movement from the canine edge‐to‐edge position. From the results of the present study, it is suggested that muscular dynamics during sleep are unique compared to that during voluntary clenching, and exert a greater mechanical load to the balancing side temporomandibular joint.
Analysis of a restored maxillary second premolar tooth by using three‐dimensional finite element method
Authors: Toparli M. , Gökay N. , Aksoy T.
Published: March 2003

In the first part of this study some physical properties of restorative materials, amalgam, glass–ionomer and composite resin were measured experimentally. In the second part a numerical study was carried out, for which the maxillary second premolar tooth was used. The tooth model was restored with composite resin and amalgam on glass–ionomer, which was used as the base material. The stress distribution investigated was the resultant of the stresses which come from the mastication force and those resulting from the contraction and expansion of restorative materials. All calculations were carried out using the finite element method and programs were written using FORTRAN 77. A load of 450 N, at an angle of 45° to the longitudinal axis was applied on the occlusal margin of the tooth. The tooth was assumed isotropic, homogenous, elastic and unsymmetrical. The distribution of compressive, tensile and shear stresses were plotted for the whole tooth structure.
The long‐term effect of oromaxillofacial trauma on the function of the temporomandibular joint
Authors: Miller V. J. , Bodner L.
Published: March 2003

Thirty patients with temporomandibular disorders (TMD) after trauma to the orofacial region were followed for 6 months. They were assessed at 10 days, 1 month, and 6 months. It was found that patients with combined fractures of the mandible and condyle showed more effects on function of the temporomandibular joint after 1 month than patients with condylar fracture only. This difference was not so apparent after 6 months. Patients with trauma but no fracture showed similar effects to those with non‐condylar fractures. There was a tendency for arthrogenous patients to develop myogenous problems with time. A group of patients with TMD but no trauma, showed more favourable long‐term response to conservative treatment. Long‐term follow‐up of these patients for TMD problems is recommended.
Factors influencing the development of dental erosion in vitro: enamel type, temperature and exposure time
Authors: Amaechi B. T. , Higham S. M. , Edgar W. M.
Published: March 2003

The influence of temperature, duration of exposure, and enamel type on the development and progression of dental erosion has been determined. Three experiments were devised as follows. Eroded lesions were produced on enamel samples with orange juice: (1) at different temperatures; (2) for different lengths of time; and (3) on bovine permanent, human deciduous and human permanent enamel. Lesion parameters (mineral loss and lesion depth) were quantified using transverse microradiography. Both lesion parameters were significantly lower at 4 °C when compared with 20 °C and 37 °C, and at 20 °C when compared with 37 °C. Lesion parameters increased significantly as the length of exposure increased, and were positively correlated (r=0·98, P<0·05) to the exposure time. Both parameters were significantly greater in bovine enamel than human permanent and deciduous enamel, and in human deciduous than permanent enamel. Lesion progression, as measured by mineral loss, was in the ratio 2·0:1·5:1·0 for bovine:human deciduous:human permanent, and by lesion depth, 1·7:1·3:1·0. In conclusion, the erosiveness of orange juice was less pronounced at a lower temperature, and increased with an increased exposure time. Erosion progressed twice as fast in bovine permanent than in human permanent enamel, and 1·5 times more rapidly in human deciduous than in permanent enamel.
Temperatures in and around mandibular fractures
Authors: Kourie J. , Volchansky A. , Cleaton‐Jones P. E. , Lownie J.
Published: March 2003

This study measured the temperature in and around mandibular fractures in 20 anaesthetized patients. A fine calibrated thermocouple attached to a digital thermometer was used to measure temperature at the bone surface margin of a mandibular fracture and 5 and 10 mm from the fracture; within the fracture against the bone at 5, 7 and 10 mm depths and at the base of 7 mm deep biopsy cavities 5 and 10 mm distant from the fracture line immediately after biopsy, then 1 and 2 min later. On the surface the temperature was approximately 1 °C warmer than at the 5 and 10 mm sites distant from the fracture. Temperature reduced at the 1 and 2 min readings after the biopsy cavity cutting. This study confirmed that the surface temperature is lower than internal bone temperatures.
Resting tongue position and its relation to the state of the dentition: a pilot study
Authors: Kotsiomiti E. , Kapari D.
Published: March 2003

The position of the resting tongue has been reportedly classified as normal or abnormal. The problems introduced by the abnormal tongue position relating to denture retention and stability have been sufficiently underlined. In the present study, the bibliography on the abnormal tongue position and its effect on denture function was reviewed. Additionally, the criteria for characterizing the tongue position as well the causes of the abnormalities, as reported in the literature, were discussed. Finally, a pilot epidemiological study was conducted, with the purpose to determine the incidence of the abnormal tongue position among edentulous patients as opposed to the dentate. The criteria used for the determination were criticized, and the mechanisms potentially leading to this habit were discussed. The findings indicate that the habit development is associated with the loss of natural teeth, therefore the mechanism relates to the functional and anatomical changes of the oral environment resulting from it. An epidemiological project has been designed, with the purpose of uncovering the associations between the observed tongue position and certain functional and anatomical features, as suggested by the present study.
Crimping of collagen in the intra‐articular disc of the temporomandibular joint: a comparative study
Authors: Berkovitz B. K. B.
Published: March 2003

Very occasional reference is made to the presence of collagen crimps in the fibre bundles of the intra‐articular disc (IAD) of the temporomandibular joint (TMJ). As the crimp structure may confer important biomechanical properties on the IAD, the present study was undertaken to determine its distribution in a variety of mammals, including humans. IADs from the rat, rabbit, guinea pig, ferret, sheep, marmoset and human were either sectioned or examined as whole mount preparations with polarized light. Apart from the guinea pig, where fibre bundles in the central region of the disc showed considerable overlap and masking of the crimp structure, the anteroposterior aligned fibres in the central region of all remaining animals showed the conspicuous presence of crimps. The periodicity of the crimp distance varied between about 10 and 30 μm. There was variation of the crimp periodicity between animals and between regions of the same disc. The crimping was associated with undulations along the length of the collagen fibres visible at the light microscope level using routine staining. The possible significance of crimping in association with internal derangement is discussed.
The pattern of toothwear amongst 12–18‐year‐old students in a Nigerian population
Authors: Ogunyinka A. , Dosumu O. O. , Otuyemi O. D.
Published: March 2003

The purpose of this study was to investigate the pattern of toothwear in the permanent teeth of 12–18‐year‐old Nigerian students. The study group comprised 176 individuals (67 males and 109 females) who had no carious cavity, restoration or fracture on any of their permanent teeth. Within the group, 86% had tooth surface loss that was limited to enamel and dentine. No statistically significant differences were observed between the sexes. The most commonly affected tooth was the lower first molar, while the occlusal surface was the most frequently involved. One student had toothwear with a predominantly erosive component as a result of frequent ingestion of low pH drinks, while another displayed toothbrush abrasion. Of those with toothwear, two (13·4%) had parafunctional activities. The cause of toothwear in 73·2% of the study population could not be ascertained. Some of it may be connected with the coarse, abrasive diets that many of the students admitted to consuming on a regular basis.
Impact of balancing‐side tooth contact on clenching induced mandibular displacements in humans
Authors: Baba K. , Yugami K. , Yaka T. , Ai M.
Published: March 2003

This study investigated mandibular displacements during clenching in the lateral mandibular position in relation to lateral occlusal relationships. Twelve healthy human subjects (mean=26·7 years) volunteered for this study. Acrylic occlusal devices were fabricated for the lower working‐side canine, working‐side second molar and balancing‐side second molar in order to simulate a dominant canine guidance, working‐side interference (WI), balancing‐side interference (BI) and bilateral balanced occlusion (BO). Vertical displacements of the mandible were recorded by linear variable differential transformers during submaximal clenching in the right lateral position. The four experimental occlusal conditions were revealed to have a significant effect on mandibular displacement patterns (ANOVA, P < 0·001). A dominant canine raiser caused a mandibular elevation with the smallest displacement at the working‐side premolar and the largest displacement at the balancing‐side second molar. Clenching on a WI or BI caused a mandibular elevation with the smallest displacement at the working‐ or balancing‐side second molar, respectively. A BO resulted in the smallest upward displacement among the four experimental conditions. These results suggest that the nature of reaction forces at the temporomandibular (TM) joints caused by the elevation of the mandible varies in a predictable manner depending upon lateral occlusal relationships.
Denture base polymer Alldent Sinomer®: mechanical properties, water sorption and release of residual compounds
Authors: Lassila L. V. J. , Vallittu P. K.
Published: March 2003

The aim of this study was to determine flexural properties, water sorption, solubility and release of residual compounds of a new paste type denture base polymer Alldent Sinomer®. In addition, an effort was made to reinforce the denture base polymer with a polymer‐pre‐impregnated glass fibre reinforcement (StickTM). Six rhombic test specimens were fabricated for the flexural test in accordance to the ISO 1567 standard. Water sorption and solubility was also determined as described in the ISO standard. Residual compound release into water was determined with the high performance liquid chromatography (HPLC) method. The flexural strength of Sinomer polymer was 85·8 MPa and flexural modulus 2·73 GPa. Storing of test specimens in water reduced the flexural strength and the modulus. By adding the glass fibre reinforcement into the test specimen, the flexural strength and the modulus increased considerably (ANOVA, P < 0·001). The increase was minor with the reinforcement of low fibre content and high with the reinforcement of higher fibre content. Water sorption of the Sinomer polymer was 26·4 μg mm–3 and solubility was 1·52 μg mm–3. High performance liquid chromatography analysis revealed the release of 0·18 wt% fraction of compound which was determined as methylmethacrylate (MMA) monomer. The results of this study suggest that the new denture base polymer Sinomer passed the requirements of the ISO standards and that its mechanical properties can be increased considerably by an incorporation of a glass fibre reinforcement. The release of MMA monomer into water from the polymer should be taken into account when the polymer is used in denture bases of patients with an allergy towards MMA.
Bonding strength between a hard chairside reline resin and a denture base material as influenced by surface treatment
Authors: Leles C. R. , Machado A. L. , Vergani C. E. , Giampaolo E. T. , Pavarina A. C.
Published: March 2003

Direct relining of dentures made with hard chairside reline resins is faster than laboratory‐processed reline systems and the patient is not without the prosthesis for the time necessary to perform the laboratory procedures. However, a weak bond between the autopolymerizing acrylic reline resins and the denture base material has been observed. This study evaluated the effect of six different surface treatments on the bond strength between a hard chairside reline acrylic resin and a heat‐cured acrylic resin. Specimens of the heat‐cured acrylic resin were divided into seven groups. One of these groups remained intact. In the other groups, a 10‐mm square section was removed from the centre of each specimen. The bonding surfaces were then treated with (i) methyl methacrylate monomer, (ii) isobutyl methacrylate monomer, (iii) chloroform, (iv) acetone, (v) experimental adhesive and (vi) no surface treatment – control group. Kooliner acrylic resin was packed into the square sections and polymerized. The bonding strength was evaluated by a three‐point loading test. The results were submitted to one‐way analysis of variance (ANOVA) followed by a Tukey multiple range test at a 5% level of significance. No significant difference was found between the surface treatment with Lucitone 550 monomer or chloroform, but both were stronger than the majority of the other groups. The bond strength provided by all the surface treatments was lower than that of the intact heat‐cured resin.
Effects of diameter, chemical impregnation and hydration on the tensile strength of gingival retraction cords
Authors: Del Rocío Nieto‐Martínez María , Maupomé Gerardo , Barceló‐Santana Federico
Published: March 2003

Gingival retraction cords are useful clinical aids but little information is available regarding desirable physical features that would preserve their integrity under tensile forces. The study aimed to establish under experimental conditions the extent to which tensile strength is affected by variation in cord diameter; impregnation with ferric sulphate (FS) or aluminium sulphate (AS); and cord hydration (wet/dry). Commercial cords and standard cotton cords were assayed in an Instron 1137 machine. Data were analysed using t‐test, and one‐ and four‐way ANOVA. Results indicated that tensile strength for 200 commercial cords was 1˙4950 ± 1˙032 kg; and for 560 cotton cords was 1˙2964 ± 1˙4560 kg. Cord hydration had no significant effect on tensile strength, whereas impregnation with AS or FS, a smaller diameter, and/or being a cotton cord decreased tensile strength (P < 0˙001). Bivariate analyses showed that hydrated commercial cords had higher tensile strength than dry specimens; hydrated or dry cotton cords were not different. The FS‐impregnated cotton cords had lower tensile strength than AS‐impregnated or control cords, and the effect was greater at higher FS concentrations. This study is one of the first evaluations of the physical properties of cords, highlighting characteristics that may minimize the risk of tearing.
Relation between cavity design and marginal adaptation in a machine‐milled ceramic restorative system
Authors: Sato K. , Matsumura H. , Atsuta M.
Published: March 2003

The purpose of the current study was to evaluate the influence of inclination of the cusp as well as convergence/divergence of the cavity wall on marginal adaptation in a machine‐milled ceramic restorative system. Sixty inlay specimens were prepared from a pre‐fabricated feldspathic porcelain (Vitablocs Mark 2) by means of a computer integrated manufacturing system (Cerec 2). Specimens were divided into 12 groups according to original cavity preparations consisting of four inclinations of the cusp (0°, 15°, 30° and 45°) and three types of cavity form (tapered box, regular box, and undercut box). The restorations were cemented with a dual‐activated luting agent (Clapearl DC) and cut into two halves with a low speed cutting saw, after which adaptation at the occlusal surface of each inlay specimen was measured with a microscope. The results showed that the inclination of the cusp did not affect adaptation of the restorations (P > 0˙05), whereas the inlay specimens inserted into undercut cavity preparation exhibited significantly poor adaptation as compared with those inserted into regular and tapered cavities in two inclinations of the cusp (0° and 15°; P < 0˙05). The experimental results suggest that either regular or tapered box form cavity preparation is preferable to the undercut box form to improve occlusal marginal adaptation of the Cerec 2 ceramic restorative system.
A study of the prevalence and distribution of dentine sensitivity in a population of 17–58‐year‐old serving personnel on an RAF base in the Midlands
Authors: Clayton D. R. , McCarthy D. , Gillam D. G.
Published: March 2003

Previous studies have reported on dentine sensitivity (DS) prevalence in hospital and general practice populations. Results from these studies indicate that perception and prevalence of DS vary depending on the population. The study aimed to determine any major differences in the perception and prevalence of DS in subjects in a military training establishment. Questionnaires from 228 subjects [188 completed by males, 39 completed by females, with one person not indicating their gender of mean age 24·0 years (s.d. 7·16)] were collected and analysed using the Statistical Package for the Social Sciences (SPSS). Fifty percent of the subjects (n=114) claimed to have DS. Yet approximately 30% of the subjects (29·8%, n=68) perceived the condition as a slight problem and approximately 40% of the subjects (40·8%, n=93) claimed it was an occasional problem and approximately 50% (49·1%, n=112) did not seek treatment. Seventeen subjects (7·5%) used a desensitizing paste during periods of discomfort. No clear pattern emerged with regard to seasonal variation in DS although 5·7% (n=13) subjects considered DS to be more of a problem in winter. Only 7·9% (n=18) reported any previous periodontal surgery, consistent with previous studies (12·6 and 15·5%). Of those who received regular scaling (27·2%, n=62), only 23 (10·1%) reported any discomfort following treatment, which did not last ≥5 days. The results indicate that self‐reporting of DS was similar to previous reports, although it is of fundamental importance that such studies should be supplemented with a thorough clinical examination to determine more reliable prevalence data.
The efficacy of intra‐articular sodium hyaluronate in patients with reducing displaced disc of the temporomandibular joint
Authors: Hepguler S. , Akkoc Y. S. , Pehlivan M. , Ozturk C. , Celebi G. , Saracoglu A. , Ozpinar B.
Published: March 2003

In this clinical trial, we examined the efficacy of intra‐articular hyaluronic acid (HA) treatment in 38 patients with reducing displaced disc of the temporomandibular joint (TMJ). Subjects received two unilateral upper space injections of HA or physiological saline solution with 1 week apart. Efficacy was based on the following measurements: pain and sound intensity of the joint measured by visual analogue scale (VAS), modified Helkimo’s clinical dysfunction index and the intensity of joint vibration during opening and closing the mouth measured by accelerometers. These measurements were performed before the first injection and 1 and 6 months after the last injection. In the treatment group (n=19), all measurements improved significantly at month 1 and at month 6 compared with the baseline (P < 0·01). The same measurements, in the placebo group (n=19), did not show any change, except for the pain intensity which improved at month 1 and month 6 (P < 0·05). The change in baseline measurements of all of the efficacy criteria at month 1 and at month 6 in the treatment group was significantly better compared with the change obtained with placebo at the same time intervals. This study demonstrates that intra‐articular sodium hyaluronate (Orthovisc®) injection into the TMJ is an effective treatment for a reducing displaced disc.
A survey of amalgam restorations in a south‐western Nigerian population
Authors: Oginni A. O. , Olusile A. O.
Published: March 2003

The present survey assessed the proportion of replacement restorations in comparison with new restorations because of primary caries in a setting where the caries experience had been reported to be low but probably on the increase. Also the relative importance of the main reasons for the replacements among other things was established. A total of 488 amalgam restorations were surveyed. About 25% of all restorations were replacements of failed restorations. The main reason for the replacement was bulk amalgam fracture, which accounted for 47˙1% of all restorations. These show a reversal of what had been reported in settings where the caries experience was high but now is on the decrease. The importance of bitewing radiograph of all failed restorations was emphasized in order to minimize under or over treatment. The median age of failed restorations was 5˙0 years. More than half (60˙3%) of replaced restorations had failed during the first 5 years of use.
Effects of hydrogen peroxide on the light reflectance and morphology of bovine enamel
Authors: Kwon Y. H. , Huo M. S. , Kim K. H. , Kim S. K. , Kim Y. J.
Published: March 2003

The purpose of this study was to examine the effects of a bleaching agent (30% hydrogen peroxide) on the surface of bovine enamel using a scanning electron microscope and a UV‐VIS‐NIR spectrophotometer. Five non‐carious bovine incisors were bleached for 0, 1, 2 and 3 days using 30% hydrogen peroxide. The light reflectance spectrum was measured using a spectrophotometer with diffuse reflectance mode. Colour values and colour differences in the teeth were evaluated from the reflectance measurements with the CIE L*a*b* colour coordinate system. Surface alterations in the bleached and unbleached teeth were studied using a scanning electron microscope. The change of reflectance in the teeth was related to the change of colour. Most reflectance change occurred within a 1‐day bleaching, and this result was confirmed by a CIE L*a*b* colour coordinate system. The colour differences in the bleached teeth were significant enough to be perceived by the observer's eye. The comparison of bleached to unbleached bovine enamel revealed that the bleached surface showed non‐uniform slight morphological alterations, and it developed varying degrees of surface porosity. This study indicates that the bleached bovine teeth showed apparent colour differences as well as slight morphological alterations after bleaching.
Effect of stabilization‐type splints on the asymmetry of masseter muscle sites during maximal clenching
Authors: Bertram S. , Rudisch A. , Bodner G. , Emshoff R.
Published: March 2003

Patients with temporomandibular disorders may present with a cluster of joint and muscle disorders characterized primarily by pain, joint sounds and irregular or deviating jaw function. Maxillary stabilization‐type splints represent the best standard therapy, so the purpose of this study was to evaluate changes in local maximal clenching‐related asymmetry patterns of masseter muscle sites associated with the immediate `application of splint therapy' using the diagnostic approach of high‐resolution gray‐scale ultrasonography. The study included 24 patients who had signs and symptoms of temporomandibular disorders. Ultrasonographic investigation was performed with a linear (B‐scan) 7·5 Mhz small‐part transducer to visualize the antero‐superior, antero‐inferior, medio‐superior, medio‐inferior, postero‐superior, and postero‐inferior sites of the masseter muscle. To assess local maximal clenching‐related muscle asymmetry patterns and to evaluate the respective effect of occluding splints, the `absolute asymmetry index' was used, with the mean maximum muscle diameter of the respective right and left sides calculated from three consecutive measurements before and after splint insertion. Comparing the values assessed before splint insertion with those after splint insertion revealed a significant decrease in local maximal clenching‐related muscle asymmetry values for the antero‐inferior masseter muscle site (P < 0·05). The results of this study suggest stabilization‐type splints to have a site‐specific effect in the immediate reduction of local maximal clenching‐related muscle asymmetries. Further studies are warranted to evaluate muscle‐site specific effects in patient and non‐patient groups and to relate these effects to pre‐treatment variables like bite force, preferred chewing side, facial morphology and occlusion.
Antibacterial and physical properties of resin modified glass‐ionomers combined with chlorhexidine
Authors: Sanders B. J. , Gregory R. L. , Moore K. , Avery D. R.
Published: March 2003

The purpose of this study was to determine the effect on mechanical properties and antimicrobial activity of the addition of chlorhexidine (CHX) to a resin modified glass‐ionomer (Photac‐fil, ESPE, Norristown, PA, USA). Chlorhexidine diacetate was combined with a resin modified glass‐ionomer material at a concentration of 5%. The samples were tested for hardness, tensile strength and erosion at 24 h and 6‐week intervals and for elution of CHX and antimicrobial activity weekly for 6 weeks. At 24 h there was no significant difference in hardness between the two groups, but at 6 weeks the resin modified glass‐ionomer group was significantly harder than the CHX groups (P < 0·05). The diametral tensile strength test indicated no difference between the control and CHX groups at 24 h or at 6 weeks. The jet erosion test demonstrated significantly less erosion with the CHX group at 24 h but at 6 weeks the CHX group showed significantly more erosion than the control group. The chemical assay data demonstrated a peak elution of CHX at week 1 with residual amounts at weeks 2 and 3. The microbial data demonstrated that the CHX group had a significant reduction in Streptococcus mutans numbers for weeks 1–3, but after week 4 there was no difference between the glass‐ionomer with and without CHX. The addition of CHX to resin modified glass‐ionomer altered hardness and erosion of the resin‐modified glass‐ionomer, but because there are no material specifications, it is difficult to determine clinical implications. Chlorhexidine did significantly improve the antimicrobial effect of the glass‐ionomer which was consistent with the chemical assay data. The results indicated that the addition of CHX to resin modified glass‐ionomer material (Photac‐fil) did not seriously degrade the physical properties during the time period tested and that the addition of CHX resulted in a greater reduction in S. mutans when compared with glass‐ionomer alone.
Treatment of habitual temporomandibular joint dislocation with miniplate eminoplasty: a report of nine cases
Authors: SHIBATA T. , YAMASHITA T. , NAKAJIMA N. , UEDA M. , ISHIJIMA T. , SHIGEZUMI M. , ARISUE M.
Published: March 2003

Summary Eminoplasty using T‐shaped titanium miniplate was performed on 15 joints in nine patients suffering from recurrent dislocation of the temporomandibular joint with several general complications. After the conventional pre‐auricular approach to the zygomatic arch and eminence, the bent over miniplate was inserted anteriorly against the articular eminence and fixed to the zygomatic arch with miniscrews to limit the over‐movement of the condyle. In one case, the miniplate fractured, but no recurrence of dislocation was observed. In another case, it was possible to evaluate the mandibular movement by Sirognathograph analysis, which proved satisfactory function of the joints.
In situ microhardness evaluation of glass–ionomer/composite resin hybrid materials at different post‐irradiation times
Authors: Basting R. T. , Serra M. C. , Rodrigues A. L.
Published: March 2003

The purpose of this paper was to evaluate in situ the microhardness of a composite resin, two resin‐modified glass–ionomers and two polyacid‐modified composite resins at different post‐irradiation times. The materials analysed were: Z 100/3M (Z1); Fuji II LC/GC Corporation (Fu); Vitremer/3M (Vi); Freedom/SDI (Fr); and Dyract/Dentsply (Dy). Palatal intra‐oral acrylic resin appliances were made for each of the 24 volunteers in the experiment. In each appliance, a specimen of each material was fixed. Microhardness tests were performed at 30 min, 1, 2, 4, 8, 24 and 48 h, 7, 10, 14, 17 and 21 days after initial light‐curing. The analysis of variance followed by the Tukey test showed significant differences of microhardness among all materials (Fu < Vi < Fr < Dy < Z1) up to 48 h. From the seventh to the fourteenth day, statistical differences were not found between Freedom and Dyract (Fu < Vi < Fr=Dy < Z1). On the seventeenth and twenty‐first days, Vitremer, Freedom and Dyract did not present statistical differences, but differed from Fuji II LC and Z 100 (Fu < Vi=Fr=Dy < Z1). The polynomial regression showed an increase of microhardness over time for the glass–ionomers/composite resin hybrid materials, although there were differences of microhardness among these materials. There was no significant changes in microhardness levels for the composite resin over time.
Evaluation of two thione primers and composite luting agents used for bonding a silver–palladium–copper–gold alloy
Authors: MATSUMURA H. , ATSUTA M. , TANOUE N.
Published: March 2003

Summary The purpose of the current study was to evaluate the bond strength and durability of two metal adhesive systems bonded to a silver–palladium–copper–gold (Ag–Pd) alloy. Disk specimens were cast from an Ag–Pd alloy (Castwell M.C. 12), air‐abraded with 50 μm grain‐sized alumina, and they were bonded with two primer‐cement bonding systems (Alloy Primer and Panavia Fluoro Cement; Metaltite and Bistite II). For each cement, unprimed specimens were also prepared as experimental controls. Shear bond strengths were determined both before and after thermocycling (4–60 °C, 1 min each, 100 000 cycles). The average post‐thermocycling bond strengths in MPa (n=8) were: 39·0 for the Metaltite–Bistite II system, 32·2 for the Alloy Primer–Panavia Fluoro Cement system, 23·1 for the Bistite II material and 21·0 for the Panavia Fluoro Cement material. The use of proprietary primers, both of which contain thione functional monomer, enhanced the post‐thermocycling bond strengths of both cements (P < 0·05). After thermocycling, however, the difference in bond strength between the two cements was not significant regardless of the use of the primers (P > 0·05). It is concluded that the combined use of the thione primer and the luting agent is necessary for bonding the Ag–Pd alloy examined.
Ultrasonographic assessment of local cross‐sectional dimensions of masseter muscle sites: a reproducible technique?
Authors: Emshoff R. , Bertram S. , Brandlmaier I. , Scheiderbauer G. , Rudisch A. , Bodner G.
Published: March 2003

SUMMARY  Local cross‐sectional dimensions (LCSDs) of masseter muscle sites may now be measured non‐invasively using ultrasonography. The purpose of the present study was to determine (i) whether the muscle site may affect LCSD measurements and (ii) whether measurements made at identical sites may be reproducible. The study included 17 patients who had signs and symptoms of temporomandibular disorders (TMD). Bilateral ultrasonographic investigation was performed with a linear (B‐scan) 7·5 MHz small‐part transducer to visualize the antero‐superior, antero‐inferior, medio‐superior, medio‐inferior, postero‐superior, and postero‐inferior sites of the masseter muscle. Measurements were made in two sessions with a time interval of at least five minutes. Data were analysed for reproducibility by using the intraclass correlation coefficient (ICC) and the method error (ME). Muscle site had no significant effect on muscle measurements (P=0·090). Measurements from the various side‐related sites did not differ significantly (P=0·425). Measurements recorded at a given site were consistent across the testing sessions (P=0·605). The muscle site with highest reproducibility was the medio‐inferior site (ICC=0·92; ME=6·4%). The data suggest that ultrasonography is a reproducible method for measuring LSCDs of the masseter muscle.
Methodology of oral sensory tests
Authors: Jacobs R. , Wu C.‐H. , Van Loven K. , Desnyder M. , Kolenaar B. , Van Steenberghed D.
Published: March 2003

SummaryDifferent methods of oral sensory tests including light touch sensation, two‐point discrimination, vibrotactile function and thermal sensation were compared. Healthy subjects were tested to assess the results obtained from two psychophysical approaches, namely the staircase and the ascending & descending method of limits for light touch sensation and two‐point discrimination. Both methods appeared to be reliable for examining oral sensory function. The effect of topical anaesthesia was also evaluated but no conclusion could be drawn as too few subjects were involved. Newly developed simple testing tools for two‐point discrimination and thermal sensation in a clinical situation were developed prior to this study and tested for their reproducibility. Thermal sensation could be reliably detected in repeated trials. Although the hand‐held instruments have some drawbacks, the outcome of these instruments in a clinical environment is suitable for assessing oral sensory function. Three different frequencies (32, 128 and 256 Hz) were used to estimate the vibrotactile function. Different threshold levels were found at different frequencies.
Effect of stabilization splint therapy on pain during chewing in patients suffering from myofascial pain
Authors: Gavish A. , Winocur E. , Ventura Y. S. , Halachmi M. , Gazit E.
Published: March 2003

summary  Masticatory myofascial pain (MFP) condition is a musculoskeletal disorder that compromises the functional capacities of the masticatory system. As such, the incorporation of an intensive chewing test as a discriminatory exercise for the diagnosis of this condition and evaluation of treatment success has considerable potential. Various splint designs have been used successfully, which have posed a question of whether the therapeutic effect of the splint is a placebo or has some other curative properties. The purpose of this study was to evaluate the efficacy of the stabilization appliance to reduce signs and symptoms in MFP patients and to compare the pain experience during the chewing test between two groups of patients, with and without splints. Myofascial pain patients (n = 37) who reported exacerbation of pain in function participated in the study. Patients perfomed a 9‐min chewing test, followed by 9‐min rest and marked their pain intensity on a visual analogue scale every 3 min. Of the 37 patients, 21 received a stabilization flat occlusal splint for night use and 16 were equally monitored clinically without a splint. At the end of 8 weeks, a second clinical examination and chewing test were performed. Student's t‐test was used to analyse differences between study groups. Analysis of variance and covariance (ancova) with repeated measures was applied to analyse the effect of treatment. Level of pain at baseline prior to the chewing test (P0) was introduced as a co‐variant. At baseline both groups showed relatively high scores of pain intensity and did not show any significant differences among the collected variables. At the end of the experiment, the splint group had a statistically significant reduction in pain intensity, in mean muscle sensitivity to palpation and in the pain experience during the chewing test compared with no change in the controls. A stabilization splint has a therapeutic value beyond its placebo effects. Thus, it should be an integral part of the treatment modalities in MFP disorder patients. An intensive chewing test is an effective tool to evaluate the treatment modality efficacy in MFP patients.
The relationship between sleep apnoea, bruxism, and the time it took the patient to seek for treatment in TMD patients
Authors: KOBAYASHI Y. , SHIGA H.
Published: March 2003

It has been suggested that the length of time from the onset of symptoms to the time the patients seek treatment and sleep disorders has a large effect on the treatment of TMD, especially in conservative treatment. In this experiment the relationship between the time it took patients to seek treatment and bruxism and sleep disorders was clarified.

Twenty female TMD patients (13 arthrogenous, 7 myogenous) in their twenties were selected. The length of time it took for the patients to seek for treatment was determined from the questionnaire. Using a wireless telemeter system, the EEG, FOG, ECG, masseter EMG, mental EMG, and respirogram of subjects were recorded throughout night and the frequency of bruxism and sleep apnoea was calculated. Bruxism was defined as those burst groups associated with muscular activities that lasted more than 5 s or had more than two bursts within 5 s. The relationship among the length of time needed to seek for treatment, frequency of bruxism and sleep apnoea was investigated.

Both the frequency of bruxism and sleep apnoea increased when the length of time it took for the patient to seek treatment was long (bruxism: r=0·650, apnoea: r=0·655, P < 0·01). The frequency of sleep apnoea increased as the frequency of bruxism increased (r=0·495, P < 0·05).

From these results it was suggested that there was a direct correlation among the three factors, the length of time it took to seek for treatment, frequency of bruxism and frequency of sleep apnoea. and when taking natural history it was imperative to pay more attention.
The effect of change of oral sensory input accordance with the experimental occlusal interference on electroencephalogram
Authors: MUSHIMOTO E. , TANAKA H. , ICHIKAWA D.
Published: March 2003

The aim of this study is to clarify the effect of the change of oral sensory input on brain function and to confirm whether it can be detected electroencephalographically.

Eight healthy dentate dental students were selected as subjects, and asked to wear the experimental occlusal interference on the right second molar for 1 week. Simultaneous recordings were made with electromyograms (EMG) and electroencephalogram (EEG) before and after maximum clenching. Evaluation by visual analogue scale (VAS) questionnaires was also done. Twelve‐session experiments were carried out over a period of 12 days. Daily changes of EMG activity of masticatory muscle, six comfort parameters (VAS), and EEG caused by premature contact were analysed statistically applying repeated measured anova and Tukey–Kramer analysis.

The discomfort which was described by VAS did not disappear during the interference period. Just after applying the interference, EMG activity during clenching was decreased significantly (P < 0·01) compared with control. Significant change in EEGs between before and after clenching were observed, that is, the percentage power fraction of β wave (%β) tends to increase. On the contrary, %α in EEGs after clenching decreased significantly (P < 0·01) compared with before clenching during the interference period, as verified by VAS evaluation.

In conclusion, it is suggested that the decrease of %α in EEGs after clenching may be caused by premature contact influence on the masticatory system, reflected in the presence of discomfort during occlusion, and somatosensor information from the occlusal sensation might be recognized in the higher centre of the brain, and the possibility of detecting change might be indicated electroencephalographically.