bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of microleakage between titanium and porcelain
Authors: Oruç Selçuk , Kama Bülent
Published: March 2003

Porcelain was applied to 30 titanium and 30 Remanium CS® disc‐shaped frameworks in order to investigate the microleakage. Each group was divided to three subgroups each containing 10 specimens and representing the different firing cycles (10 specimens for opaque+dentine; 10 specimens for opaque+dentine+enamel; and 10 specimens for opaque+dentine+enamel porcelain+glaze application). All the specimens were stored in 37 °C distilled water for 2 weeks and subjected to 100 thermocycles between 5 and 55 °C with 30 s dwell time. The specimens were then stored in 5% basic fuchsin dye for 2 days. The washed, rinsed and air dried specimens were embedded in autopolymerizing resin and sectioned diametrically. The stereoptical investigations were performed by three independent investigators. The data were analysed by the Mann–Whitney U‐test. The statistical analysis revealed that the different number of firings does not affect the amount of microleakage. However, it should be emphasized that the use of titanium would be beneficial regarding the relatively lower values obtained from the titanium–porcelain group.
An in vitro investigation into the wear effects of glazed, unglazed and refinished dental porcelain on an opposing material
Authors: Al‐Wahadni A. M. , Martin D. M.
Published: March 2003

A machine designed to simulate the physical parameters of masticatory function was used to investigate the amount of wear produced on perspex plates opposing discs of porcelain which were glazed, unglazed or finished to varying stages of a polishing sequence recommended with a proprietary finishing kit. The perspex specimens were abraded, under water at 37 °C for a total of 800 000 contacts using a contact time of 0·2 s, a sliding distance of 15 mm and a constant load of 0·19 N/mm2. Assessments of the wear of the perspex were based upon depth measurements of the wear track recorded on surfometric tracings. Further measurements of the cross‐sectional area of the wear track were made using an image analysing computer. The investigation confirmed that the best finish and least abrasive surface was produced by glazing of porcelain. The finish produced by intermediate components of the proprietary finishing kit did not reduce the abrasiveness of the porcelain surface. It was necessary to complete the polishing sequence with diamond paste to achieve a surface which approached the wear characteristics of glazed porcelain. It is recommended that any adjusted porcelain restoration should be re‐glazed or subjected to a finishing sequence which is followed through to a final stage of polishing with a diamond paste.
An evaluation of acrylic complete‐dentures using the discrimination of elastic bodies or viscous fluids
Authors: Inoue K. , Fujii K. , Kanie T. , Kadokawa A. , Tsukada G.
Published: March 2003

The discrimination test on elastic bodies and viscous fluids was carried out for 16 young dentists and 13 denture patients, because it is considered that dentures affect the ability to discriminate food. The materials used in this test were six thermoplastic polyurethane elastomers with compressive elastic moduli from 11·8 to 62·0 MPa and six silicone impression pastes with coefficients of viscosity from 1·77×10−2 to 23·0×10−2 MPa · s. The subjects (dentists and patients) discriminated the materials based on differences in elastic moduli or coefficients of viscosity by chewing the materials for 10 s. From these experiments, it became clear that the ability to discriminate between elastic bodies or viscous fluids upon chewing, of subjects who use complete‐dentures in combination with their own teeth and either an upper or lower complete‐denture (S/D) or who have a set of complete‐dentures in both jaws (D/D) decreased considerably, compared with that of subjects who have their own teeth in upper and lower jaws (S/S). The ratios of S/D and D/D against S/S were 0·5 and 0·3, respectively. This indicates that with an increase in the area occupied by dentures in the oral cavity, the value of the differential threshold increased markedly and made food discrimination more difficult. In addition, discriminating viscous fluids was 2·4 to 3·1 times more difficult compared with the discrimination of elastic bodies, independent of denture placement.
The study of jaw reflexes evoked by electrical stimulation of the lip: the importance of stimulus intensity and polarity
Authors: Okdeh A. M. , Lyons M. F. , Cadden S. W.
Published: March 2003

The aim of this study was to investigate whether reported differences in the patterns of jaw reflexes which can be evoked by electrical stimulation of the lip might be related to the intensity or polarity of the stimuli. Constant‐current stimuli were applied through bipolar electrodes clipped across the lower lip of 14 subjects while EMG recordings were made from a masseter muscle. During stimulation, the subjects sustained a level of masseter activity equivalent to 10% of their maximum. The stimuli were applied as multiples of sensory threshold. The EMGs were analysed following rectification, averaging and smoothing. A sequence of inhibitory, excitatory, inhibitory and excitatory responses could be produced in the muscle by both polarities of stimuli. The latencies of these four responses were generally in the ranges 10–20, 25–40, 40–55 and 80–100 ms, respectively. These latencies, particularly for the last two responses, tended to decrease at higher intensities of stimulation. The threshold for the long‐latency inhibition was significantly lower than that for the short‐latency inhibition when the cathode was outside the mouth but not when it was inside the mouth. In addition, the long‐latency excitation had the lowest threshold of the four responses regardless of stimulus polarity. Since nerves are excited particularly around a cathode, we interpret these results as showing that stimulation of nerves supplying the skin outside the mouth evokes predominately long‐latency jaw reflexes whereas shorter latency responses can be evoked by stimulating nerves supplying oral mucosa. Furthermore, long latency excitatory reflexes seem to be the most easily evoked by stimulation of the lip.
Fluoride release/uptake of polyacid‐modified resin composites (compomers) in neutral and acidic buffer solutions
Authors: Attin T. , Buchalla W. , Siewert C. , Hellwig E.
Published: March 2003

The aim of the present study was to evaluate the fluoride uptake/release of polyacid‐modified resin composites (compomers) in neutral and acidic buffer solutions. Two compomers (Dyract® and Compoglass®) were tested and the conventional glass–ionomer cement (GIC) Vivaglass Base® served as a control. Forty specimens were fabricated from each of the respective materials. Twenty of these specimens were placed in artificial saliva and the other 20 specimens in a fluoridated dentifrice slurry for 5 min. Then, 10 fluoridated and 10 non‐fluoridated specimens were immersed in a neutral buffer solution (pH 6·8), and the other specimens were immersed in an acidic solution (pH 4·0). After 1, 2, 3, 4, and 5 days the samples were again placed in either a fluoridated dentifrice slurry or saliva for 5 min, after which time they were transferred to fresh buffer solutions. The fluoride content of the solutions was assessed with a fluoride sensitive electrode. Fluoride release from all the materials decreased continuously during the experiment, with a significantly higher release in the acidic solution compared to the neutral buffer solution. Fluoridation did not result in an increased fluoride release for the compomers. However, the conventional GIC revealed a significantly higher fluoride release after fluoridation. It is concluded that Dyract® and Compoglass® can not be replenished with fluoride, irrespective of the pH value of the environment.
Comparison of the retentive and photoelastic properties of two prefabricated endodontic post systems
Authors: Cohen B. I. , Pagnillo M. , Musikant B. L. , Deutsch A. S.
Published: March 2003

This in vitro study compared the retention and photoelastic stress patterns from two loading conditions, vertical (133·2 N, 30 pounds) and oblique at a 26° angle (133·2 N, 30 pounds) for two prefabricated post systems. The post studied were: (1) Flexi‐Post® (a split‐shank threaded post) and (2) C‐Post® (a carbon fibre bound in an epoxy resin, passive double taper tier post). Two groups with 10 specimens per group were subjected to retentive forces with a universal testing machine (MTS 810 Material Testing Machine). In addition, two photoelastic test blocks were prepared with simulated root canals for each post studied. After cementation the photoelastic blocks were photographed before vertical and oblique loading and after loading. One‐way analysis of variance (
anova) for retention data revealed a highly significant difference (P≪0·0001) between groups. The Flexi‐Post® had a statistically higher mean retention force of 1180·6 N (265·9 pounds), while the C‐Post® had a mean of 171·8 N (38·7 pounds). Photoelastic analysis indicated minimal stresses for both the Flexi‐Post® and C‐Post® in the unloaded state. The C‐Post® showed asymmetrical apically stress patterns, while loaded in both states. The multi‐tiered system of the Flexi‐Post® clearly distributes stress symmetrically, while the C‐Post® distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi‐Post® are more favourable than the asymmetric, uneven stresses and relatively low retentive strength for the C‐Post®.
Finite element analysis of the effect of vertical curvature on half‐oval cast clasps
Authors: Sato Y. , Tsuga K. , Abe Y. , Akagawa Y.
Published: March 2003

High stresses in half‐oval cast clasps are the main causes of deformation or fracture. A vertical curvature in clasps is said to be effective in reducing stress. However, such claims lack scientific basis. The purpose of the present study was to evaluate stress and stiffness in a three‐dimensional (3D) finite element analysis (FEA) model of clasps with different vertical curvatures, cross‐sectional forms and tapers, and to clarify the effect of vertical curvature on the half‐oval cast clasp. Circumferential clasp arms for the mandibular second premolar were analysed by 3D FEA. The clasp arms were approximated by curved cantilever beams with a half‐oval cross‐section around a cylinder. The radius of curvature was set at 4 mm and the angle subtended by the clasp arm was 120°. The clasp tip was set at a point 2 mm lower than the base. In the ‘No‐taper’ half‐oval clasp arm, stress increased and stiffness decreased with the increase in vertical curvature. In the shape of a preformed wax pattern (thickness/width=0·80, tip/base=0·70), stress and stiffness decreased slightly. In an ‘Original’ form (thickness/width=0·33, tip/base=0·80), vertical curvature had a very slight effect on stress and stiffness, and stress was the lowest. These findings suggest the superiority of the ‘Original’ form, with less stress and no effect of vertical curvature.
Energy‐based re‐evaluation of Angle's Class I molar relationship
Authors: Hisano M. , Soma K.
Published: March 2003

The energy used to break down food was calculated in Angle Class I and rigid interdigitation, as well as in various malocclusions using a computer simulation. As a result, the energy applied to the food was the highest in Angle's Class I molar relationship and rigid interdigitation, with a simple pattern of masticatory movement. This relationship also tended to produce maximum efficiency in the posterior teeth, including the premolars. Furthermore, energy decreased with the degree of malocclusion. Thus, we were able to provide an alternative definition of Angle's Class I molar relationship and rigid interdigitation. In addition, the extent of malocclusion could be evaluated quantitatively.
Simplified method of estimating masticatory performance
Authors: AL‐Ali F. , Heath M. R. , Wright P. S.
Published: March 2003

Methods which measure masticatory performance include gravimetric, volumetric and direct observation which depend on the weight, volume and size, respectively, of a test food once chewing is completed. Almonds, one of the most common test foods used, have a convenient size and texture. However, due to their oily content and mixing with saliva, washing and drying is required to overcome the clumping of chewed particles. A method has been developed using bagged almonds to exclude saliva and preventing loss of almond particles in the mouth. In addition, microwaving the whole almond reduces the oil content of the almond, reducing clumping, and potentially eliminating the need for washing and drying the particles. A dentate volunteer was asked to chew seven blanched almonds and seven microwaved almonds. The chewed particles were separated using two sieves, weighed and optically scanned to measure the number and area of the particles. Results were obtained both before and after washing and drying of the chewed particles. The overall results for the test of masticatory performance is very similar whether or not a washing stage is used for microwaved almonds. For untreated almonds washing has a more noticeable effect and may still be considered necessary.
Interactions between thermal cycled resilient denture lining materials, salivary and serum pellicles and Candida albicans in vitro. Part I. Effects on fungal growth
Authors: Nikawa H. , Jin C. , Hamada T. , Murata H.
Published: March 2003

In the present study, the growth of a single isolate of Candida albicans on seven saliva‐, serum‐coated or protein free (uncoated), thermocycled (4–70 °C for 1 min, respectively; 0, 1000 and 10 000 times) commercial resilient lining materials was investigated by monitoring pH changes in growth media. The inhibitory effect of the tissue conditioners on fungal growth was observed using three parameters, i.e. (i) the delay in the onset of the rapid decline in pH, (ii) the reduction in the rate of pH change and (iii) the pH minima reached. In the case of control soft liners (not thermocycled and uncoated), the antifungal effect appeared to depend upon the type of commercial soft liner used. Thus, an initial delay in pH decline and a very high pH minima were observed with fluoric and heat‐cured silicone materials. High pH minima were also observed with cold‐cured acrylic soft liners, whereas cold‐cured silicone materials did not significantly differ from heat‐cured acrylic resin (P>0·05). However, the antifungal effect of the materials was significantly reduced both by thermal cycling (anova, P<0·01) and a layer of protein coating (saliva, P<0·05; serum, P<0·01). These results, taken together, suggest that the ageing of the materials and the biological fluids of the host, particularly serum, promote yeast growth on soft lining materials.
Mandibular position at chin‐point guided closure, intercuspation and final deglutition in asymptomatic and temporomandibular dysfunction subjects
Authors: Čelar A. G. , Kundi M. , Piehslinger E. , Fürhauser R. , Kohlmaier B.
Published: March 2003

This study compared the mandibular position at chin‐point guided jaw closure, intercuspation and final deglutition (position at the end of swallowing) in 159 asymptomatic subjects and 142 subjects with symptoms in the craniomandibular system. The symptomatic subjects were assigned to four groups showing an adapted centric posture, pain, luxation with reduction of the temporomandibular joint and pain with luxation and reduction. Computer equipment aided recording of hinge axis movements in three dimensions. While the three positions differed significantly in anterior–posterior direction on both sides and in inferior–superior direction on the right, a significant difference between asymptomatic and symptomatic subjects existed only in final deglutition on the left side and in the anterior–posterior location of the guided closure. Final deglutition did not coincide with the guided closure or the intercuspation in approximately 89%. A proportionally large standard deviation gave evidence against a strict relationship of the three positions in asymptomatic and symptomatic subjects. Because of this variability, final deglutition was not recommended for verification of centric relation or the intercuspal position.
Bonding agent is a decisive factor in determining the marginal leakage of dental composites subjected to thermal cycling: an in vitro study
Authors: Mathew M. , Parameswaran Nair E. K. , Krishnan V K.
Published: March 2003

The marginal leakage at the dentine/composite interface in Class II composite restorations subjected to thermal cycling has been effectively evaluated using the silver staining technique. The presence of a bonding agent at the dentine/composite interface is found to improve adhesion. Scanning electron and optical microscopic observations of sectioned specimens reveal that applying a second coat of bonding agent on the dentinal surface helps in reducing microleakage compared to a single coat application, in all three radiopaque composite/bonding agent systems studied (Z100/Single Bond, Spectrum TPH/Prime & Bond 2·1 and Chitra/Chitrabond 1·0). Thermal cycling during in vitro studies was found to provide a more appropriate representation of the adhesive behaviour of the composite in clinical situations.
Adverse effect of dentine bonding agent on the oral mucosa of guinea pigs
Authors: Manabe A. , Katsuno K. , Kurihara A. , Itoh K. , Hisamitsu H. , Wakumoto S. , Iijima M. , Yoshida T.
Published: March 2003

The purpose of present study was to determine the possibility of nebulous discoloration of the oral mucosa of guinea pigs as a result of the application of dentine bonding agents. The materials used were the Clearfil® Photo Bond (CPB) system's mixture agent, universal agent and catalyst agent. Four types of experimental catalysts were used. In male albino guinea pigs weighing 300–500 g, oral mucosa irritation tests were performed in accordance with the guidelines of the Cosmetic, Toiletry and Fragrance Association (CTFA). Macroscopical findings on the oral mucosa showed that there was strong nebulous discoloration immediately after application of CPB mix and CPB catalyst and throughout the experimental periods. However, CPB without 10‐methacryloxdecyl dihydrogen phosphate (MDP) did not produce noticeable nebulous discoloration and inflammation. The CPB mix caused pathological changes, such as paraketosis and hyperkeratosis on the endepidermis of the mucosa, immediately after its application.
Effect of addition of ethyl alcohol on gelation and viscoelasticity of tissue conditioners
Authors: Murata H. , Hamada T. , Harshini  , Toki K. , Nikawa H.
Published: March 2003

The clinical effectiveness of tissue conditioners is influenced by their gelation characteristics and viscoelastic properties after gelation. The purpose of this study was to evaluate the effect of addition of ethyl alcohol (EtOH) on these properties, and to compare the effect of EtOH with that of the powder/liquid (P/L) ratio. Three tissue conditioners were used in this study. The gelation times were obtained with an oscillating rheometer. The viscoelastic properties after gelation were also evaluated by stress relaxation tests. Addition of greater amounts of EtOH produced the shorter gelation time and the larger flow after gelation. Conversely, although the use of a higher P/L ratio produced a shorter gelation time, this procedure leads to a smaller flow after gelation. The results suggested that the addition of EtOH to the liquids of tissue conditioners is an effective method for controlling gelation times and viscoelastic properties after gelation.
Evaluation of the utility of cephalometric parameters in constructing complete denture. Part II: placement of anterior teeth
Authors: Bassi F. , Rizzatti A. , Schierano G. , Preti G.
Published: March 2003

Various types of parameters, including cephalometric ones, have been used in the construction of complete denture. This study aimed to evaluate the utility of cephalometric parameters for this purpose. The position of the anterior teeth in a group of 42 edentulous patients, successfully rehabilitated with complete denture according to clinical parameters, was evaluated by cephalometrics following the Ricketts’ design. Data obtained were then compared statistically with those reported by Ricketts for dentate subjects, the position of the maxillary incisors was slightly anterior.
Microwave‐cured acrylic resins and silicone–gypsum moulding technique
Authors: Del Bel Cury A. A. , Rached R. Nunes , Ganzarolli S. Maria
Published: March 2003

This study evaluated the residual monomer (RM), Knoop hardness (KHN) and transverse strength (TS) of two microwave‐cured acrylic resins (Acron MC® (A), GC Dent. Ind. Corp., Tokyo, Japan and Onda Cryl® (O), AO Classico Ltda, São Paulo, Brazil) when processed with an all‐type III gypsum moulding technique (G) or a silicone–gypsum moulding technique (S). One hundred and forty four specimens were fabricated and equally distributed into four groups (AG, AS, OG and OS). The TS tests were conducted after 48 h of water storage, and KHN values were obtained after 24, 48, 72 h and 30 days. The RM was determined every 24 or 48 h over a period of 288 h. The acrylic resins were prepared and processed according to the manufacturer’s directions. Both AS and OS showed the highest means (P < 0·05) for RM (μg cm–2) only after 24 h (AS = 56·84 ± 27·39/AG = 7·51 ± 5·75/OS = 3·59 ± 1·60/OG = 1·02 ± 0·3), 48 h (AS = 28·99 ± 9·35/AG = 2·65 ± 2·17/OS = 2·37 ± 0·84/OG = 0·68 ± 0·49) and 72 h (AS = 15·98 ± 9·01/AG = 1·40 ± 0·57/OS = 1·87 ± 0·52/OG = 0·75 ± 0·44). Both AS and OS showed the highest means (P < 0·02) for KH after 24 h (AS = 18·69 ± 2·3/AG = 17·79 ± 0·7/OS = 18·41 ± 1·0/OG = 16·04 ± 0·6). After 48 h the mean values for OS and OG differed significantly (P < 0·03) (OS = 18·67 ± 0·8/OG = 16·75 ± 0·8). No differences of KHN were found among the groups during the storage periods. The TS values for A and O were not affected by either G or S (P > 0·05). Silicone–gypsum mould technique affected the RM and KHN of the resins in the first 2 and 5 days of analysis, respectively. The type of mould did not affect TS, and the acrylic resins differed from each other for all properties regardless of the type of mould.
Clinical evaluation of a chemically cured hard denture relining material
Authors: Matsumura H. , Tanoue N. , Kawasaki K. , Atsuta M.
Published: March 2003

The purpose of the current study was to evaluate the clinical performance of a chemically cured denture relining material after 1‐year service period. A powder–liquid material designed for denture base relining (Tokuso Rebase Normal‐set, Tokuyama Corp., Tokyo, Japan.) was assessed. Fifty adult patients, who required denture reline treatment, participated in the current project. Adaptation of each denture was examined with a silicone elastomeric material, and the surface to be relined was reduced by means of a rotary cutting instrument, then conditioned with dichloromethane. The relining material was spatulated, poured into the relining area, inserted and adjusted after setting. Each relined denture was subjected to base line evaluation immediately after relining and end evaluation after 1 year. Standardized criteria were used for direct evaluation of the material. After an observation period of 1 year, the rate of the relining cases considered to be in clinically ideal condition (Alfa) was 90% for staining, 90% for discoloration, 94% for peeling, 96% for adaptation and 100% for irritation to oral tissue. Only one case was judged as clinically unacceptable (Charlie), and this was for staining. On the basis of a 1‐year observation, the Tokuso Rebase material is considered to be a clinically reliable hard denture relining agent.
The use of the transmandibular implant system in extreme atrophy of the mandible; a retrospective study of the results in two different hospital situations
Authors: Verhoeven J. W. , Cune M. S. , Van Kampen F. M. C. , Koole R.
Published: March 2003

This retrospective study aims to investigate and compare the results obtained with the transmandibular implant (TMI) in two different hospital situations. Group I were patients treated in a teaching hospital since 1984 by a varying group of surgeons and prosthodontists with a varying degree of experience with the TMI. Group II were patients treated in 1993 and 1994 by experienced surgeons and prosthodontists in the hospital where the TMI was originally developed. In group I, a relatively high frequency of reversible (45·4%) and irreversible – i.e. implant loss – (15·2%) complications occurred. In group II, no implants were lost and reversible complications were reported in 10·8% of the patients. In general, the patients of both groups were quite satisfied with the result of the treatment. In both groups, limited bone loss around the implant posts could be observed. An increase in the height of the mandibular bone distal of the lateral posts was frequently observed, especially in group II. It is concluded that both very favourable and less favourable results can be obtained with the TMI. In this study the best results are found in a highly specialized TMI centre, where patients are treated – with only uncompromised implant‐posts – by a small group of experienced surgeons and prosthodontics with accurate application of the existing guidelines.
The influence of different jaw positions on the endurance and electromyographic pattern of the biceps brachii muscle in young adults with different occlusal characteristics
Authors: Ferrario Virgilio F. , Sforza Chiarella , Serrao Graziano , Fragnito Nicola , Grassi Gianpiero
Published: March 2003

To investigate the hypothesis of a functional coupling between the stomatognathic motor apparatus and the muscles of other body districts, as well as between occlusal conditions and neuromuscular performance, two groups of men (age range 20–26 years), with either normal occlusion (14 men) or malocclusion (15 men), sustained with their dominant arm a dumbbell weighing 80% of their maximum while maintaining different jaw positions: mouth open, without dental contact; mouth close, with light dental contact; maximum voluntary clench; maximum voluntary clench on two cotton rolls positioned on the posterior mandibular teeth; maximum voluntary clench on one cotton roll positioned on the right/left‐side posterior mandibular teeth. Surface electromyography (EMG) of the biceps brachii muscle was performed, and the endurance time, mean root mean square (rms) potential, and mean median power frequency were computed. The mean potential and median power frequency were also computed for 2‐s windows, and values as a function of time were interpolated by a linear regression analysis. Data were compared between groups and trials by using a factorial analysis of variance. The malocclusion group subjects could perform the exercise for a longer time span than the normal occlusion individuals (P < 0·005). During this endurance time their biceps brachii muscles contracted with different patterns: on average, in the malocclusion group they had a larger EMG amplitude (P < 0·005), and a shift of the power spectrum toward lower frequencies (P < 0·005). The factor ‘jaw position’ was significant only for the endurance time (P < 0·005). In both groups, the longest endurance time was found in the ‘clench’ trial, while the shortest in the ‘right‐side bite’ trial. In conclusion, a morphologically altered occlusion does not always worsen the muscular performance of other body districts, and the use of occlusal supports (cotton rolls) is not always beneficial.
Severe tooth loss among UK adults – who goes for oral rehabilitation?
Authors: McGrath C. , Bedi R.
Published: March 2003

A random probability sample of 2667 United Kingdom (UK) addresses was selected in a multistage sampling process. Participants were interviewed about their oral health status – number of teeth possessed and denture status. In addition information was collected about their socio‐demographic characteristics (age, gender, social class and income level) and dental service factors – type of service used and difficulty accessing national health service (NHS) care. The response rate was 70%. Six percent (107) claimed they had less than 20 teeth but did not use a denture. Variations in this practice were apparent in relation to a number of socio‐demographic factors: age (P < 0·05), gender (P < 0·01) and social class (P < 0·001) but not service related factors. In regression analysis, social class, gender and age emerged as important predictors of this practice. For example, those from lower social classes were approximately half as likely to use dentures despite experiencing considerable tooth loss (OR=0·53, 95% CI 0·34, 0·83), having controlling for other factors. More than one in 20, in Britain claim they have experienced considerable tooth loss but are without resource to a denture. Socio‐demographic factors rather than service related factors are associated with this practice, particularly social class.
Accuracy of check‐bite registration and centric condylar position
Authors: Utz K.‐H. , Müller F. , Lückerath W. , Fuß E. , Koeck B.
Published: March 2003

In a dentate subject a jaw relation can either be determined in maximum intercuspation and is as such given by the occlusal morphology, or the mandibular position can be allocated according to the centric position of the condyles. For comprehensive restorative treatment or analytic measures of the occlusion it is important to record the centric condylar position. Various registration methods have been described in the literature, but there is no consensus on which is the `best'. The aim of the present study was therefore to assess the accuracy of various registration methods and evaluate a possible influence of the used materials. Four dentists were involved in the clinical part of the study, another was responsible for the measurements. Impressions were taken from 81 fully dentate volunteers. The casts were mounted by face‐bow transfer and central‐bearing‐point (CBP) registration into Dentatus® articulators. Subsequently the centric condylar position was determined with six different methods and materials, respectively. Each method was reproduced twice so that a total of 18 registrations was performed per patient. The mandibular positions which resulted from the individual registrations were then repeatedly compared in the condylar area using a computer supported specially modified measuring articulator. The accuracy was found best for the unrefined wax wafer registration (x=0·33 mm) and with an average of 0·44 mm worst when using acrylic wafers. The CBP and frontal jig methods as well as tin‐foil and refined wax wafers showed an accuracy in‐between these boundaries. The biggest measured mandibular displacement between any two registrations were considerably 2·0 mm. However, the described differences in accuracy between the various methods and materials proved statistically not significant. All investigated jaw registrations showed an accuracy of about 20 times the tactile fine sensibility of natural teeth which has to be taken into account when inserting fixed prosthetic restorations in centric condylar position. Despite meticulous clinical and technical procedures small occlusal adjustments are therefore almost unavoidable.
The effect of thermocycling on peel strength of six soft lining materials
Authors: Sertgöz A. , Kulak Y. , Gedi̇k H. , Taskonak B.
Published: March 2003

The bond strength of two heat‐cured and four cold‐cured soft lining materials was compared using a peeling test method before and after thermocycling. Tested soft lining materials were Molloplast B, Mollosil, Ufigel P, Ufigel C, Permaquick and Permaflex. Six specimens, 6·5 × 2 × 0·3 cm, for each group were prepared according to the manufacturers' instructions. Control groups were stored in a humidor for 24 h, whereas the others were thermocycled in a water bath between the 5 and 55 °C for 5000 cycles. Peel strength of samples were measured using an Instron Universal testing machine at a cross‐head speed of 5 mm min–1. The types of failure were observed using an electron microscope. The highest peel bond strength values were calculated for Permaflex and Permaquick before and after thermocycling, respectively. Molloplast B, Mollosil, Ufigel P and Permaquick demonstrated an increase in peel strength after thermocycling, with Permaquick lining material having statistically significant increase. However, decrease in peel strength was observed for Ufigel C and Permaflex after thermocycling. Failure mode within the control groups was cohesive for Molloplast B, Permaquick and Permaflex, whereas adhesive for Ufigel P and Ufigel C. Mollosil demonstrated a mixed mode of failure for both thermocycled and control groups.
Changes of blood flow in the mucosa underlying a mandibular denture following pressure assumed as a result of light clenching
Authors: Akazawa H. , Sakurai K.
Published: March 2003

The aim of this study was to investigate the influence of the continuous compression assumed as a result of light clenching on the blood flow of the denture underlying mucosa in tissue‐supported or tooth‐tissue‐supported denture wearers. Measurements were carried out on eight removable partial denture wearers (three males and five females, from 50 to 72 years, mean age: 61·5 years). The blood flow in the denture underlying mucosa was measured at the unilateral mandibular first molar region using an experimental denture base equipped with a laser Doppler flowmeter. The area of the experimental denture base was 2 cm2, and the loading force was 1 kgf. The loading time was set at 5, 10, 20, 30 and 60 s. The blood flow after 20 s loading was <15% in rest. The times from release of loading to the maximum blood flow and from release of loading to recovery up to 110% of the blood flow at pre‐loading were significantly prolonged by an increase in the loading time. Even if it is light, a continuous clenching results in ischaemia and delays the recovery of blood flow in the mucosa underlying the denture after release of compression.
In vitro evaluation of the effect of a current bleaching agent on the electrochemical corrosion of dental alloys
Authors: Canay Şenay , Çehreli̇ Murat C. , Bi̇lgi̇ç Semra
Published: March 2003

summary  The nightguard bleaching of discoloured teeth is currently performed by using % 10 carbamide peroxide. While the material is effective on the bleaching of natural teeth, it may deteriorate crowns, bridges and amalgam restorations placed in the mouth. The purpose of the present study was to investigate the effect of 10% carbamide peroxide on the electrochemical corrosion of various dental casting alloys used for fixed partial dentures and dental amalgam. Tafel extrapolation curves were obtained by the corrosion cell that facilitated simulation of the oral enviroment and comparison of the corrosion rates of alloys and amalgam was accomplished. The results revealed that unpolished amalgam and nickel‐chromium alloy samples had the most and noble alloys had the least corrosion rate.
Marginal gap formation of composites in dentine: effect of water storage
Authors: Yap A. U. J. , Shah K. C. , Chew C. L.
Published: March 2003

summary  This study investigated the effects of water storage on the marginal adaptation of two composite resins (Spectrum TPH and Ariston AT), two polyacid‐modified composite resins (Dyract AP and F2000) and a new PRG composite (Reactmer) to dentine over time. Two cylindrical dentine cavities (1·5 mm diameter and 1·5 mm deep) were prepared on the horizontally sectioned surfaces of freshly extracted teeth. In each tooth, one cavity was restored using composites with their respective bonding system and the other without the bonding system. The sample size for each material with/without bonding system was 6. The composites were placed in one increment, bulk‐polymerized, immediately finished/polished with the Sof‐lex discs system and fine polished on 30 μm silicon carbide/9 μm aluminium oxide lapping film discs in a microgrinding system. The specimens were then stored in distilled water at 37 °C and the maximum marginal gap width between the material and the dentine wall was determined at 24 h, 1 week, 2 weeks, 3 weeks and 4 weeks using a measurescope at ×500 magnification. Results were subjected to statistical analysis using monva, anova/Scheffe's post hoc test and independent samples of t‐test at significance level 0·05. At all time intervals, no significant difference in marginal gap formation was observed between materials. Where bonding systems were not used, a decrease in gap widths over time was observed with most materials but only Dyract AP exhibited a significant decrease. The latter was observed after 2 weeks storage in water. The use of bonding systems reduced dentine marginal gaps significantly and is therefore mandatory for all composites evaluated. Marginal gaps arising from polymerization contraction of conventional, polyacid‐modified and PRG composites cannot be fully compensated by hydroscopic expansion. Clinical relevance Bonding systems are mandatory for all composites when bonding to dentin. In the event of a bond failure at placement, hygroscopic expansion of composites can reduce marginal gaps but not completely.
Experimental salivary pellicles formed on the surface of self‐curing resin
Authors: Yoo J.‐H. , Kho H.‐S. , Kim Y.‐K. , Lee S.‐W. , Chung S.‐C.
Published: March 2003

summary  The aim of this study was to identify the salivary components present in the pellicles formed on self‐curing resin and to investigate the qualitative variations in adsorbed salivary pellicle compositions according to different exposure time to saliva. Experimental pellicles were formed by the incubation of polymerized resin particles with fresh human parotid or submandibular‐sublingual saliva for either 20 min or 2 h. Pellicles were extracted using formic acid and lyophilized, they were then subjected to sodium dodecyl sulphate–polyacrylamide gel electrophoresis and immunoblotting to identify the adsorbed salivary components. The amino acid profiles of the 2 h‐pellicles were analysed and compared with those of fresh glandular salivas. There was a difference in the 2 h‐pellicle components on the self‐curing resin compared with those of other dental materials as well as tooth enamel. The amino acid profiles of the 2 h‐pellicles were also different from those of fresh glandular salivas. In the case of submandibular‐sublingual saliva, the components of the 2 h‐pellicle showed a different pattern compared with those of the 20 min‐pellicle. However, there was no significant difference between the components of the 2 h‐ and 20 min‐pellicles in the case of parotid saliva. A distinct difference was found in the surface binding affinities of immunoglobulin (IgA) from different glandular salivas. The findings of this study provide information concerning the initial bacterial adhesion on the surfaces of self‐curing resin.
Relation between clenching strength and occlusal force distribution in primary dentition
Authors: Karibe H. , Ogata K. , Hasegawa Y. , Ogihara K.
Published: March 2003

summary  The aim of this study was to investigate the relation between clenching strength and occlusal force distribution in primary dentition. Twenty healthy children with normal occlusions: 11 boys and 9 girls, ages 3·2–5·8 years (avg. 4·5 years) were selected. Setting the bilateral masseter muscular activity at maximum clenching in full intercuspation as 100%, the occluding forces at 20, 40, 60, 80 and 100% clenching were recorded with pressure‐sensitive sheets (Dental Prescale 50H, type R, Fuji Photo Film Co.), and the force of each primary tooth was analysed by computer (Occluzer FPD703). Occlusal force distribution was expressed as a percentage of the total occlusal force of each tooth and was compared between each clenching. There were no significant differences between various clenching strengths in the occlusal force distribution in primary dentition [one‐way repeated‐measures analysis of variance (anova)]. Thus, the results of the present study suggest that the distribution of occluding forces on a primary dental arch had its own pattern and that the clenching strength had no effect on that pattern. These patterns may be useful in determining occlusal function in children.
Validation of the clinical diagnostic criteria for temporomandibular disorders for the diagnostic subgroup of degenerative joint disease
Authors: Brandlmaier I. , Grüner S. , Rudisch A. , Bertram S. , Emshoff R.
Published: March 2003

summary  Research is needed to assess the validity of the Clinical Diagnostic Criteria for Temporomandibular Disorders (CDC/TMD). The purpose of this study was to test the reliability of the clinical diagnosis of temporomandibular joint (TMJ) degenerative joint disease (DJD) as compared with the magnetic resonance imaging (MRI) ‘gold standard’. The TMJ DJD group comprised 48 joints in 24 consecutive patients who were assigned a clinical bilateral diagnosis of TMJ DJD. The TMJ non‐DJD group consisted of 82 joints in 41 consecutive patients without a TMJ‐related diagnosis of TMD. Bilateral sagittal and coronal MR images were obtained subsequently to establish the corresponding diagnosis of degenerative joint changes. An MRI diagnosis of osteoarthrosis (OA) was defined by the presence of flattening, subchondral sclerosis, surface irregularities, and erosion of the condyle or presence of condylar deformities associated with flattening, subchondral sclerosis, surface irregularities, erosion and osteophyte. For the CDC/TMD interpretations, the positive predictive of DJD for OA was 67%, and for the presence of degenerative joint changes 88%. The overall diagnostic agreement for DJD was 44·6% with a corresponding K‐value of 0·01. Most of the disagreement was due to false‐negative interpretations of asymptomatic joints. The results suggest CDC/TMD to be predictive for degenerative joint changes but insufficient for determination of OA. Patients assigned a clinical TMJ‐related diagnosis of DJD may need to be supplemented by evidence from MRI to determine the presence or absence of OA.
Tooth contacts at the mandibular retruded position, influence of operator's skill on bite registration
Authors: Yamashita S. , Igarashi Y. , Ai M.
Published: March 2003

summary  Occlusal conditions at the retruded contact position (RCP) have been thought to be among the aetiological factors for temporomandibular disorders. However, the role of these occlusal factors still remain unclear. The purpose of a series of studies was to investigate the locations of RCP contacts and to discuss their implication by the authors. In the study reported here, the influence of the operator's skill on bite registration was surveyed. Eighty‐six dental students were selected as subjects. One specialist in prosthetic dentistry moved the subject's mandible up and down while guiding it gently backward until it rotated on its retruded axis. Once the initial tooth contacts were established, the operator checked them by using a thin articulating paper (direct method). On the other hand, six younger operators following precise instruction from the specialist about the technique of jaw guidance examined each of the subjects for location of RCP contacts using the indirect method. Silicone‐based impression material was used for bite registration while the subject kept the jaw at this contact position (indirect method). Wilcoxon signed rank test was applied to evaluate differences between the expert operator and six younger operators regarding locations of RCP contacts. Results from the expert operator (direct method) showed that tooth contact at the first premolar was most frequently observed and the number of subjects who possessed unilateral tooth contacts was more than that with bilateral tooth contacts. On the other hand, in the case of the indirect method performed by younger operators, tooth contact patterns significantly differed from those of the direct method.
The changing emphasis of mental health and learning disability nurse education in the UK and ideal models of its future development
Authors: Norman
Published: March 2003

This paper reports the findings of a research study funded by the English National Board for Nursing, Midwifery and Health Visiting (ENB), which explored the impact of community care reforms on mental health and learning disability nurses and their practice. In this study we were struck by the divergent views of our respondents about the nature of mental health and learning disability nursing as practice disciplines and the implications of these views for the future shape of preregistration educational preparation. We noted, in particular, the debate between those who advocate what is referred to as specialist educational preparation and others who favour generic preparation. The specialist‐generic debate is relevant to nursing as a whole but was magnified in the context of our study because genericism was perceived by many of our respondents as a threat to the minority branches and especially to those (arguably mental health and learning disability) that are not rooted in the biomedical tradition of general nursing. This paper seeks to contribute to this debate as it impinges on the two nursing specialties by developing models of future nurse education grounded in the empirical data from our research and interrogating them to draw out their central features. Two models are clearly independent: the ‘specialist’ and the ‘generic’ models. Another three models are partial in that they draw upon the first two: the ‘pragmatic’ model, the ‘unity‐of‐nursing’ model, and the ‘social care’ model. A common feature of the pragmatic and unity‐of‐nursing models is that they support the existing DipHE programme, which is now the dominant form of preregistration nurse preparation in the UK. The social care model is applicable principally to learning disability nursing.
The use of leisure activities in a therapeutic community
Authors: McCaffrey
Published: March 2003

This paper is concerned with the use of social and leisure activities as part of nursing work in a therapeutic community. It describes this element in the therapeutic programme of the Cassel Hospital. There is a brief introduction to the general principles of the therapeutic community and then to the nurses' role at the Cassel Hospital. The work in the sphere of social and leisure activities is seen as consistent with these principles. The structures enabling social and leisure activities to be integrated into the work of the hospital are described. Therapeutic opportunities are outlined, which arise when nurses work alongside patients in the course of such activities. This also serves to illustrate therapeutic community practice. There follows a discussion of the clinical significance of the voluntary element in this area of practice and of the related problems. Jacques' conceptualization of work and resistance to work are used at a number of points to link issues raised in the paper to existing psychodynamic theory.
Influencing mental health nursing practice through the teaching of research and theory: a personal critical review
Authors: Gordon
Published: March 2003

This paper will critically review the factors that influence the teaching of theory and research to mental health nurses. Following a brief historical review it is asserted that current educational approaches fail to address the complexity and context‐dependent nature of mental health nursing practice. The author then argues for a radical approach to education which will enable students and practitioners to engage critically in deconstructing and developing theories that illuminate and help us understand the multiple realities of our post‐modern professional world. In conclusion, the author provides an example of a casework‐based curriculum that emphasizes the ways in which clinical experience with clients in a range of contexts should be the main focus of knowledge and skill development for the emerging profession of mental health nursing.