bluuebunny/crossref_metadata_2025 huggingface dataset:
The production of secondary caries‐like lesions on cavity walls and the assessment of microleakage using an in vitro microbial caries system
Authors: GILMOUR A. S. M. , EDMUNDS D. H. , DUMMER P. M. H.
Published: June 2007

The aim of this study was to assess microleakage along restored cavity walls using a new in vitro microbial technique. Extracted human teeth containing cavities restored with a microfine posterior composite were incubated in broth inoculated with a single strain of Streptococcus mutans for 10 days, using a sequential batch culture technique. Each margin of the cavities was finished in one of three ways: butt joint and etching; butt joint and no etching, or; bevel joint and etching. The assessment of microleakage was achieved by examining sections of the teeth histologically using polarized light for the presence or absence of caries‐like cavity wall lesions. Outer (surface) lesions were also examined and displayed the characteristic zones of early natural caries lesions. The cavity wall lesions were observed as a translucent zone in 31% of butt and unetched margins, 16% of butt and etched margins, and 5% of bevelled and etched margins.
Microleakage in alloy‐glass ionomer lined amalgam restorations after thermocycling
Authors: ARCORIA C.J. , FISHER M.A. , WAGNER M.J.
Published: June 2007

Marginal microleakage was measured around amalgam restorations lined with alloyglass ionomer cement and coated with a glass ionomer varnish. Preparations were made in 48 human extracted mandibular molar teeth. Alloy‐glass ionomer liners and varnishes were placed into selected preparations. Tytin amalgam was inserted into all of the teeth and left unburnished and unpolished. Half of the total samples were thermocycled for 5 days and the remainder were left in deionized water. The teeth were immersed in a 0.5% methylene blue dye and sectioned vertically with a diamond saw. Microleakage was scored visually at xl00 magnification, and the data were analysed using the Mann‐Whitney U‐test (P≤0.05). Thermocycling did not have a significant effect on microleakage, except when both an alloy‐glass ionomer liner and varnish were used. Overall, the use of an alloy‐glass ionomer liner made the most significant difference in reducing microleakage.
The effect of etching on glass polyalkenoate cements
Authors: AGGART S. E. T , PEARSON G. J.
Published: June 2007

The effect of acid etching on the surface appearance and flexural strength of four glass polyalkenoate cements was investigated. Specimens were etched for intervals of 10–60 s, both at the recommended time after mixing and after a 24‐h delay. The surface texture was examined microscopically. Further specimens were subjected to a 4‐point bend test following etching 1 h and 24 h after mixing. Deterioration of the surface appearance occurred as the etching time was increased beyond 10 s following immediate etching. Etching after 24 h reduced surface damage, but a 10‐s etch still gave the most favourable surface appearance without loss of particulate material.

Etching beyond 10 s significantly reduces flexural strength.
A comparison of two methods for locating the intercuspal position (ICP) whilst mounting casts on an articulator
Authors: WALLS A.W.G. , WASSELL R.W. , STEELE J.G.
Published: June 2007

The accuracy of two different techniques for locating casts in the intercuspal position (ICP) in a semi‐adjustable articulator was assessed. The techniques for establishing the ICP were a polyether interdental registration, or location of the casts in a position of maximum interdigitation using tactile and visual methods.

Fifty‐three sets of study models were used in this investigation. Each set of study models was mounted on two occasions, once with each of the two techniques. The models were divided into two groups at random, and mounting and assessment procedures were performed using a single blind crossover design. The quality of the contacts between the mounted casts was compared with the results of an occlusal examination of the same subjects.

Hand articulation of the casts prior to mounting the lower cast against the upper cast was a more accurate means of locating the ICP than the use of a low‐viscosity polyether interdental registration material, unless there were difficulties in establishing the ICP by visual and tactile methods.
Occlusal contacts in maximum intercuspation and craniomandibular dysfunction in 16‐ to 17‐year‐old adolescents
Authors: GIANNIRI A.I. , MELSEN B. , NIELSEN L. , ATHANASIOU A.E.
Published: June 2007

The relationship between number, distribution and intensity of occlusal tooth contacts and the craniomandibular functional status was investigated in 56 subjects aged 16–17 years. The photocclusion technique was used for the qualitative and quantitative evaluation of occlusal contacts, and a clinical examination was performed to assess the function of the stomatognathic system. According to a matched‐pairs design two groups were formed, one consisting of individuals with signs of craniomandibular disorders, and the other consisting of functionally healthy adolescents. The pairs were matched according to morphological occlusal characteristics.

The results of the present study emphasize the importance of occlusal contacts in relation to craniomandibular function. In particular the posterior occlusion appeared to be related to function, since statistically significant differences between the two groups were detected with regard to the number and load of contacts. Symmetry of intensity rather than symmetry of contact distribution per se seemed to be important in relation to craniomandibular function.
Mandibular reaction time to auditory and visual signals in young and elderly subjects
Authors: NAGASAWA T. , YUASA Y. , TAMURA H. , TSURU H.
Published: June 2007

Mandibular reaction time was measured in young and elderly volunteers. Each subject was instructed to open the jaw from the closed position and to close the jaw from the open position as quickly as possible after perceiving an auditory or visual signal. The reaction time of the elderly subjects to both signals was significantly slower than that of the young subjects. This was due almost entirely to prolongation of the premotor time component. There was no difference in the maximum velocity of the jaw movement between the two groups of subjects.
Reflected light microscopy of the human mandibular condyle – a study of a post‐mortem material
Authors: JAGGER R. G.
Published: June 2007

The surface characteristics of the articulating surfaces of 11 human mandibular condyles removed post‐mortem were determined by the use of reflected light dark‐field microscopy. Good agreement was obtained between macroscopical grading of degenerative change and appearance as observed by microscopy. Microscopical appearances believed to correspond to normal surface, fibrillation and degenerative changes are described.
Stimulus‐response latencies of two instruments delivering transcutaneous electrical neuromuscular stimulation (TENS)
Authors: GOMEZ C. E. , CHRISTENSEN L. V.
Published: June 2007

Stimulus‐response latencies of low‐frequency transcutaneous electrical neuromuscular stimulation (TENS) were studied in 15 healthy subjects, applying the two different pulse configurations delivered by the Biotens and the Myomonitor instruments. Latencies, in milliseconds, were determined on bipolar raw surface electromyograms (EMG) of the suprahyoid muscles, using the skin surface over the sigmoid notches of the mandible as the site of stimulation. Stimulus‐response times were measured from the onset of the stimulus artefact to the first response peak on EMG, and their mean values showed ranges of 3.79–4.49 ms for Biotens and 5.10–5.34 ms for Myomonitor. It was concluded that low‐frequency TENS caused direct stimulation of motor nerves, and that the timing of the contraction response was not affected by altered electrode placement, lead‐wire reversal or unbalanced (right/left) stimulation.
An electrognathographic study of aspects of ‘deprogramming’ of human jaw muscles
Authors: CARR A.B. , DONEGAN S.J. , CHRISTENSEN L.V. , ZIEBERT G.J.
Published: June 2007

Three‐dimensional electrognathography of an incisor point was used to detect peripheral correlates of deprogramming of the jaw elevator muscles. Putative deprogramming was attempted through the clinically recommended use of a leaf gauge, placed for 10–15 min between the maxillary and mandibular anterior teeth and disoccluding the posterior teeth by about 2 mm. Studied mandibular displacements were those that occurred during voluntary elevation of the mandible from the postural to the intercuspal position. Use of the leaf gauge did not affect the displacement patterns. Within a freeway space of about 0.2 mm3, the incisor point moved about 2 mm vertically, about 1 mm sagittally, and about 0.2 mm laterally.
Thermal effect on the dissolution of mercury from two dental amalgams
Authors: SOH G. , CHEW C. L. , LEE A. S. , YEOH T. S.
Published: June 2007

Various factors affect dissolution of mercury from dental amalgams. In this study we examined the effect of temperature on the release of mercury from two dental amalgams, namely an admixed high‐copper amalgam (Contour) and a new tin‐ and copper‐free amalgam (Composil). Ten cylindrically‐shaped specimens of each type of amalgam were used in this investigation, and were divided into two equal groups. The five specimens in each group were each incubated in 10 ml purified water at either 37°C or 60°C, with a change of water every 24 h over an 8‐day period. The quantity of mercury released from each amalgam specimen during each incubation period was expressed as μg cm−2 24 h−1. The amount of mercury released was estimated by cold‐vapour atomic spectrometry. The results demonstrate that specimens incubated at 60°C released significantly larger amounts of mercury than specimens incubated at 37°C for both types of amalgam. The release of mercury by Composil was significantly greater than that by Contour (P≤0.0001) for both temperatures studied. Raising the incubation temperature caused a disproportionate increase in mercury release from Composil compared to Contour.
Shortened dental arches and periodontal support*
Authors: WITTER D.J. , DE HAAN A.F.J. , KÄYSER A.F. , VAN ROSSUM G.M.J.M.
Published: June 2007

The periodontal support of subjects with shortened dental arches (SDA, n=74), and of subjects with SDA and free‐end removable partial dentures in the lower jaw (SDA and RPD, n=25) was compared with that of subjects with complete dental arches (CDA, n=72). The periodontal support was determined by tooth mobility and alveolar bone height, measured on a radiograph, of the distal alveolar bone of the premolars. Significant differences in tooth mobility were found between the three groups of subjects. The relative bone height showed a trend towards lower values for the SDA group and the SDA and RPD group. For some teeth these differences were significant. Premolars that are the most posteriorly located occluding teeth in the dental arch tend to have a lower relative alveolar bone height than premolars in an intermediate location. This effect is more marked in the upper jaw than in the lower jaw. Premolars in the lower jaw, that serve as abutment teeth for free‐end RPDs, tend to show lower values for the relative bone height.

It is concluded that the differences between the three groups with regard to the periodontal support are small. The large amount of crowns and bridges in both the SDA and SDA and RPD groups, and the dental history of these subjects, resulting in SDA, should be taken into account. However, as indicated by the periodontal breakdown of premolars in some subjects with SDA, the combination of an existing severe periodontal involvement and a SDA is considered to be an unfavourable situation.
Occlusal force pattern during rhythmic human tapping movement
Authors: MUNAKATA Y. , TSUJI M. , KASAI S.
Published: June 2007

The dynamic occlusal force patterns associated with the performance of rhythmic tapping movement were analysed in normal subjects, who were instructed to make tapping movements at four frequencies, 2, 2.5, 3.3 and 5 Hz, with as constant a magnitude of force as possible. The occlusal force recorded by an intra‐oral customized device showed a triphasic pattern which could be divided into two components, and this pattern was more clearly defined during slower tapping movements. Of the two components, the first was relatively stable, regardless of changes in tapping frequency, while the second was highly dependent on the tapping cycle duration, and its duration was shortened with increases in tapping frequency. Furthermore, there was a significant correlation between the changes in the occlusal power phase and those in the burst duration of the masseter EMG simultaneously recorded by a pair of surface electrodes. On the basis of these findings, it is suggested that the tapping rhythm is modulated by the duration of the occlusal power phase and the associated jaw elevator muscle activity.
Effectiveness of fortnightly tooth brushing with amine fluorides in caries‐prone subjects
Authors: RAN F. , GEDALIA I. , FRIED M. , HADANI P. , TVED A.
Published: June 2007

The aim of this study was to assess the caries incidence and plaque accumulation in schoolchildren at caries risk, after brushing the teeth fortnightly with gels containing 0, 0.4% F, 1.25% F as amine fluoride (AmF) or the common amine fluoride toothpaste containing 0.125% F. The study was conducted double blind over an 18–month period, and after 6 months discontinuation of brushing. Only the group that brushed with the 1.25% AmF gel showed a significant decrease in caries development compared to the group that brushed with the 0.125% AmF toothpaste. During the 6‐month discontinuation period, the incidence of caries increased in all groups: the differences in caries development between all groups were not significant. Plaque indices were significantly lower in the AmF‐treated groups. The highest fluoride concentration in the gel reduced the development of caries to zero, probably due to increased fluoride levels in the oral milieu of caries risk children. In order to maintain a positive effect of fluoride over an extended time period, caries‐prone subjects should continue an initiated fluoride programme.
Functional stress modification after high condylectomy surgery
Authors: ALEXANDRIDIS C. , CAPUTO A.A. , ELIADES G.C.
Published: June 2007

Surgical removal of the head of the condyles inevitably leads to radical redistribution of loads applied to the mandible. The nature of this redistribution can have important implications on the surgical approach and subsequent reconstructive procedures. The purpose of this investigation was to visualize photoelastically the functionally delivered stresses after high condylectomy surgery. Three identical models of a dentate human mandible were constructed from a photoelastic material. One mandible simulated a unilateral and the other simulated a bilateral high condylectomy. The third mandible had both condyles intact and served as basis for comparisons. Silicone implants were placed on the sectioned condylar heads. The condyles, with the silicone implants, were fitted into simulated fossae and the mandibles were loaded unilaterally and bilaterally. The resulting stresses were observed and photographed in the field of a circular polariscope.

Substantial differences in load‐generated stresses were observed as a result of both unilateral and bilateral condylectomies, compared to the normal case. The most severe stress conditions occurred with the unilateral condylectomy, where stresses associated with torsion were most evident.
Residual monomers (TEGDMA and Bis‐GMA) of a set visible‐light‐cured dental composite resin when immersed in water
Authors: TANAKA K. , TAIRA M. , SHINTANI H. , WAKASA K. , YAMAKI M.
Published: June 2007

Rods of a visible‐light‐cured dental composite resin were photo‐polymerized and immersed in water at 37°C for 7 days. The residual monomers (TEGDMA and Bis‐ GMA) trapped in the set composite and those eluted into water were analysed by gas‐liquid chromatography. It became evident that minor amounts of the residual monomers dissolved in water, but that most residual monomers remained in the set composite. Extension of the irradiation period contributed to the significant reduction in the residual monomer level and its elution into water.
Mandibular manipulation of anterior disc displacement without reduction*
Authors: JAGGER R.G.
Published: June 2007

The history and clinical symptoms of anterior temporomandibular joint disc displacement without reduction are characteristic, and include limitation of mandibular movement and mandibular deviation on opening of the mouth. Twelve consecutive patients attending a clinic with such symptoms were treated by mandibular manipulation. An immediate increase in the range of mandibular movement was obtained for all patients, with a mean increase in interincisal opening of 8mm. The method of manipulation is described, and the implications of the results for the treatment of TMJ patients are discussed.
Tooth enamel softening with a cola type drink and rehardening with hard cheese or stimulated saliva in situ
Authors: GEDALIA I. , IONAT‐BENDAT D. , BEN‐MOSHEH S. , SHAPIRA L.
Published: June 2007

The in‐situ remineralization effect of hard cheese was compared with that of saliva on tooth enamel in man. The intra‐oral test of softening enamel surfaces by a cola type drink followed by rehardening by chewing hard cheese and/or parafilm was assessed by microhardness and SEM measurements. Cheese consumption significantly increased the enamel hardness, whereas stimulated saliva did not have this effect. The remineralizing effects are presumably due to uptake of calcium and phosphate salts by the surface enamel. Morphologically, the enamel surfaces did not return to their original state.
Sex differences in signs and symptoms from masticatory and other muscles in 19‐year‐old individuals
Authors: KROGSTAD B. S. , DAHL B. L. , ECKERSBERG T. , ØGAARD B.
Published: June 2007

Pain and tenderness of masticatory muscles are often related to muscle tenderness elsewhere in the body. It has been shown that women are more prone to musculo‐skeletal disorders than men. We sought to determine whether sex differences of muscular symptoms were established by the age of 19. The subjects comprised 51 boys and girls who received a questionnaire regarding the function of their masticatory system, frequency of headache, and neck, shoulder and low back pain. Their masticatory system was examined, and neck and shoulders were palpated. For all variables in the questionnaire girls reported symptoms more often than the boys. Of the subjects 50% had tender chewing muscles upon palpation. Again the girls had the most. There was good correlation between reports of pain in one area as compared to others. The number of clinically tender neck and shoulder muscles correlated with the number of tender masticatory muscles. It was concluded that girls presented more muscular symptoms than boys.
Complete mandibular denture stability when posterior teeth are placed over a basal tissue incline
Authors: JOOSTE C.H. , THOMAS C.J.
Published: June 2007

Six patients with previous denture experience were provided with new dentures. Metal indicators were placed on either side of the mandibular denture and a cobalt‐chromium alloy marker was inserted in the left bucco‐posterior area of the mandible in each case. In the new dentures posterior teeth were positioned up to the retro‐molar pad, over the basal tissue slope of the posterior mandibular alveolar ridge. After habituation had taken place, a cineradiographic recording was made of chewing. Prior to the second recording the mandibular teeth were removed to a point where the remaining teeth were not over inclined residual alveolar ridges. Denture movement was observed by measuring the distances between the markers on an analytical projector. The results show a significant difference between the cranial values of the two chewing experiences. Values for all denture movements were less after removal of the teeth over an incline. These results support the clinical observation that teeth placed over a basal tissue incline have a destabilising effect during complete mandibular denture function.
Longitudinal study on occlusal force distribution in lower distal‐extension removable partial dentures with circumferential clasps
Authors: OGATA K. , MIYAKE T. , OKUNISHI M.
Published: June 2007

In this study, longitudinal changes of the occlusal force distribution ratio were examined in lower distal extension removable partial dentures with cast circumferential clasps. Occlusal force applied to the denture base and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 4 months after. Two rates of loading were chosen. One was simulated mastication (fast loading rate) and the other was 10 Ns‐1 (slow loading rate). Location of the loading points were first premolar (PI), second premolar (P2) and first molar (P3) of the denture. The occlusal force distribution ratio to the retainers was calculated when a load of 20N was applied to the loading point.

The results are summarized as follows: (1) The occlusal force distribution ratio at fast loading rate on P1 and P2 was changed until 1 or 11/2 months after the insertion of the new dentures, and then became constant. This constant value was 30% on P1, 20% on P2 and 10% on P3. (2) Slow loading rate produced a greater ratio than the fast loading rate on P2 and P3 while there were no remarkable differences in the ratio between both loading rates on P1.
The recording and analysis of EMG and jaw tracking. I the recording procedure
Authors: HOWELL P. G. T. , JOHNSON C. W. L. , ELLIS S. , WATSON I. B. , KLINEBERG I.
Published: June 2007

A computer‐based system is clescribccl which records and analyses electromyographic (EMG) signals and tracking data for mandibular movements during function! EMG signals were obtained bilaterally from six muscles and ii Sirognathograph monitored the postion of the lower incisor teeth in three dimensions. Directed jaw movement tasks by subjects were monitored These data were continuously sampled at a rate of 1 KHz per channel oven an operator controlled period.

Analysis of the data was performed off‐line following the experiment. Individual chweing cycles associated with masticatory function were identified and the timing and dimensions of each chewing envelope established Corresponding EMG values were also determined and displays of EMG and jaw movement were plotted on a common time base an average chewing cycle and correlated EMG activity could also be displayed on a high resolution monitor and plotted for a hard copy to enable a comparison to be mad between subjects with and without jaw dysfunction.
Bending strength of Fuji® and Ketac® glass ionomers after sonication
Authors: ARCORIA C.J. , BUTLER J.R. , WAGNER M.J. , VITASEK B.A.
Published: June 2007

Glass ionomer cements mixed by conventional methods contain voids that can decrease their overall strength. This study evaluated the effect of sonication on the reduction of air entrapment by measuring the bending strength in glass ionomer cements (Fujj‐II® and Ketac‐fil®). Glass ionomer cement was placed in identical‐test vials and sonicated for 45s, 10s, or 0s. The bending strengths were measured (0.005 in min−1) after setting times of 1 or 2 weeks. Mean bending strengths (MPa ± SD) for the 12 treatment both cements (P<0.001) and sonication times (P<0.001). The effect of setting time produced minimal increases in bending strength (P<0.218). The sonication of freshly mixed glass ionomer cements is a possible solution for reducing voids to increase bending strength.
Characterization of inorganic fillers in visible‐light‐cured dental composite resins
Authors: KHAN A.M. , SUZUKI H. , NOMURA Y. , TAIRA M. , WAKASA K. , SHINTANI H. , YAMAKI M.
Published: June 2007

Summary Inorganic fillers in seven visible‐light (VL)‐cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro‐filled and sub‐micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types.

In conclusion, wide varieties exist in the inorganic fillers in VL‐cured dental composite resins currently utilized.
In‐vitro and in‐vivo wear profile of composite resins
Authors: SATOU N. , KHAN A.M. , SATOU K. , SATOU J. , SHINTANI H. , WAKASA K. , YAMAKI M.
Published: June 2007

The aim of this study was to evaluate in‐vitro wear by two types of slurry of 10 commercial composite resin materials (seven hybrid and three microfilled composites). There was great variation in the in‐vitro wear pattern by two types of slurry. The wear rate of microfilled composites was greater than that of hybrid composites, and a negative correlation was observed between wear rate and Knoop hardness values among all materials when hydroxyapatite slurry was used. In contrast, the wear rate of hybrid composites was greater than that of microfilled composites when abraded by green carborundum slurry. These abraded surfaces were compared with SEM micrographs of in‐vivo composites surface after 4 years of service. The profile of in‐vivo wear surfaces was found to be similar to that of in‐vitro wear surfaces abraded with hydroxyapatite slurry.
Idiopathic cervical lesions: in vivo investigation by oral microendoscopy and scanning electron microscopy. A pilot study
Authors: BEVENIUS J. , ĽESTRANGE P. , KARLSSON S. , CARLSSON G.E.
Published: June 2007

The development and progression of cervical lesions have not been thoroughly documented. Clinically, two morphologically distinct forms, saucer‐or wedge‐shaped, have been described. In this study, the micromorphology of manifest cervical lesions was documented in six subjects, by SEM replication and microendoscopy. Optoelectronic recordings were made of extreme mandibular lateral excursions. Salivary parameters were evaluated and a detailed case history, including oral hygiene and dietary habits, was taken.

Lesions of varying severity could be observed in the same subject. Longitudinal fractures of the enamel were common. The dietary analyses were uneventful and salivary values were normal. No correlation was found between brushing habits and the location and severity of the lesions. The optoelectronic recordings, however, indicated a possible correlation between irregular lateral excursion and the severity and location of the lesions, with a tendency for fewer and less severe lesions on the preferred chewing side. The results have indicated some areas of interest for future studies applying non‐invasive observation methods.
Posterior palatal seal adaptation: influence of processing technique, palate shape and immersion
Authors: SYKORA O. , SUTOW E. J.
Published: June 2007

Accuracy of fit of denture bases is critical to adequate retention. This study compared the dimensional change of a newer continuous‐injection technique with a standard trial‐pack technique as determined by measuring the posterior palatal border opening. The influence of palate shape and immersion were also assessed.

Stone casts were made from master moulds with either a high or flat palate. Denture base adaptation was measured at 5 mm intervals across the entire posterior palatal border. Measurements were made after deflasking, trimming and polishing, and after immersion in room temperature water for l h, 1 day and 1 week. Statistical analysis (P < 0.05) showed that where differences occurred between the two techniques, openings were always smaller for the continuous‐injection technique. It was also shown that dimensional changes were always larger for the flat palate compared with the high palate. Dimensional change using the continuous‐injection technique was reduced by immersion in water, while no influence was observed for the trial‐pack technique. It was concluded that the continuous‐injection technique showed smaller dimensional changes compared with the standard trial‐pack technique, and that these changes were influenced by palate shape and immersion in water.
A comparison of three finite element models of an edentulous mandible provided with implants
Authors: MEIJER H.J.A. , STARMANS F.J.M. , BOSMAN F. , STEEN W.H.A.
Published: June 2007

The stress distribution in an edentulous mandible provided with two implants in the interforaminal region was calculated by means of three different finite element models. The implants were connected with a bar or remained solitary. The first model was a three‐dimensional representation of the entire mandible, the second model of the interforaminal region of this same mandible, whilst the third model was a two‐dimensional representation of the interforaminal region. The differences in stress distribution around the connected implants and the solitary implants between these three models were analysed.

It can be concluded that for a parameter study the stress distribution around the dental implants following from a three‐dimensional finite element model of only the interforaminal region of an edentulous mandible can be used. For such studies therefore, benefit can be gained from the advantages of reduced modelling and calculation time.
Longitudinal study on torque around the sagittal axis in lower distal‐extension removable partial dentures
Authors: OGATA K.
Published: June 2007

The purpose of this study was to examine the longitudinal changes of torque around the sagittal axis in lower distal‐extension removable partial dentures. The torque transmitted from the denture base to retainers was measured on several separate occasions from the insertion of new dentures to about 2 months after it. The maximal mean value of torque (Max.MT) was calculated from the magnitude of all chewing strokes of the minimum of the interocclusal distance. The integration values of torque (I) and time (T) from initiation of chewing to swallowing were obtained and then the average value of torque (Ave.T) was calculated (Ave.T= I/T).

Subjects could be divided into two groups. Max.MT and Ave.T were almost constant in one group while they were remarkably decreased in another. After 1 month of insertion of new dentures the value of both groups was within the range of less than 3 × 10‐3 kgm (1 kgm = 9.8 Nm) of Max.MT and less than 1 × 10‐3 kgm ss‐1 of Ave.T.
The use of intermediary resins when bonding glass polyalkenoate (ionomer) cement to composite resin
Authors: WOOLFORD M.J. , GRIEVE A.R.
Published: June 2007

This study was designed to examine the effects of three different types of glass polyalkenoate lining cement combined with three different types of bonding resin and varying surface treatments on the seal between the lining cement and the composite resin as used in the so called ‘laminate’ technique. The seal was assessed using a radioisotope and autoradiographic technique.

Results showed that all the cements behaved in a manner specific to them. The seal of all systems examined could be improved, or at least, not compromised, by modification of the surface of the cement prior to attachment of the resin. Only one type of intermediate resin gave a reliable seal when applied to an unmodified surface of any of the cements under investigation.

It is concluded that all the glass polyalkenoate cements tested behave differently when used beneath composite resin. Recommendations about the laminate restoration technique must be related to the specific combinations of materials used.
The release of chlorhexidine from modified dental acrylic resin
Authors: WILSON S.J. , WILSON H.J.
Published: June 2007

A method for the incorporation of chlorhexidine into acrylic resin using monomer together with the pattern of release of chlorhexidine from treated resin into water at 37°C is described. Release from polished and unpolished resin, and from acrylic prepared by short‐curing and dry‐curing processes are investigated.

The pattern of release in all cases was of an exponential nature, showing a rapid release within the first 10 days becoming almost constant at a level of 0.4‐1.5 μg cm‐2 at about 20 days. Release was still evident at the end of the test period in all cases. Release of chlorhexidine into water from the short‐cure specimens was accompanied by release of monomer, evident from the odour of the test solutions, indicating that polymerization was not complete.
Acoustic myography in the assessment of human masseter muscle
Authors: L'ESTRANGE P.R. , ROWELL J. , STOKES M.J.
Published: June 2007

The feasibility of examining electro‐mechanical activity of the human masseter muscles using non‐invasive recording techniques was examined in six healthy dentate adults (aged 34‐57 years). Electrical activity of the muscle was examined by surface electro‐myography (EMG) and the mechanical activity, in the form of muscle sounds, was examined by acoustic myography (AMG).

Bilateral recordings of EMG and AMG were made simultaneously using composite probes which were placed on the skin over the masseter muscles. A standardized pressure was applied to the probes via adjustable rods attached to a safety helmet. Pressures were monitored by strain gauges placed between the ends of the rods and the probes. With the subject seated, recordings of AMG and EMG were obtained during maximal jaw clenching for 4s and the raw signals were stored on a computer. Of three maximal contractions performed, the last two were used in the analysis. The raw amplified signals underwent frequency analysis by fast Fourier Transform. Total activity was also assessed after amplification, full‐wave rectification and integration, and repeatability of the results was assessed.

The AMG frequency range was 6‐15 Hz and was similar to values for other human skeletal muscles. The integrated values for EMG and AMG were repeatable on both sides of the face (IEMG, right r = 0.99, left r = 0.99; IAMG right r = 0.70, left r = 0.71). Simultaneous recordings of AMG and EMG from the masseter muscles may be useful for assessing electro‐mechanical muscle function but further validation studies are required before the technique can be used clinically.
Variables affecting the fracture toughness of resin‐based inlay/onlay systems
Authors: ÜÇTAŞLI S. , WILSON H.J. , ZAIMOGLU L.
Published: June 2007

The fracture toughness of five different resin‐based inlay/onlay materials was investigated by means of critical stress intensity factor (KIC) using the SEN three‐point bending test procedure (BS 5447: 1977). KIC values were determined from specimens prepared by both the direct and indirect techniques. Tests were performed immediately, after 1 day, 1 month and 3 month time intervals. Also, fractured surfaces of specimens were observed using SEM photographs.
Disc movements over the condylar head. Radiographical study on autopsy materials
Authors: MEUNISSIER M. , MEUNIER A. , CARPENTIER P. , MARGUELLES‐BONNET R. , YUNG D.O. J.P.
Published: June 2007

A radiographical study has been performed to evaluate the movement of the disc posterior band over the condylar head during mandibular opening. Six formal free embalmed subjects were selected as ‘normal’. Micro stainless steel balls were used as landmarks both into the bone and into the disc for X‐ray identification. The data was processed at each phase of movement in selected planes. The true coordinates of each disc landmark gave the potential to calculate the linear length of their path and any distance change between them. It can be concluded that there is a 5% width reduction during the opening movement and it also suggests strongly that a fair amount of translation movement between the disc and the condyle occurs in the lower compartment.
The stability of temporary prosthetic base materials II: water sorption and its effects
Authors: HEATH J.R. , BORU T.K. , GRANT A.A.
Published: June 2007

The bases of occlusal rims and trial dentures may sorb water during disinfection procedures, adjustment in the mouth and rinsing and cooling under running water. Such sorped water may adversely affect the properties of the baseplate materials. The room temperature water sorption of sheets of grey and pink shellac and cold cure acrylic resin was determined over 10 weeks by weighing. The Wallace surface hardness, linear dimension and transverse strength were also measured each week. Specimens were reweighed each week as they dried at room temperature. At the conclusion of the tests, the materials showed a change after soaking in weight, hardness, linear dimension and transverse strength, and change after drying relative to original mass for grey shellac of +1.5%, ‐48%, +0.7%, ‐58%, +0.33%; for pink shellac of +2.0%, ‐56%, +0.9%, ‐65%, +0.4%; and for acrylic resin of +1.2%, +10%, +0.4%, ‐30%, ‐2.1% respectively. The acrylic resin material was thus less affected by water sorption than the grey and pink shellac materials.
Photoelastic evaluation of the standard bionator appliance
Authors: STEFANAC J. , CHACONAS S.J. , CAPUTO A.A. , GRIFFITH J.
Published: June 2007

A study was undertaken to demonstrate the forces in the craniofacial complex generated by the activation of the standard bionator appliance. A three‐dimensional skull replica of an orthodontic patient with a Class II Division 1 malocclusion in the mixed dentition was fabricated using a urethane based photoelastic material to simulate bone. Four muscles of mastication were simulated on the photoelastic model. Various anatomical areas of the skull were viewed in a circular polariscope and recorded photographically before and after inserting the bionator.

The downward and forward repositioning of the lower jaw by the bionator appliance caused various stresses on the craniofacial complex. The photoelastic stresses visualized in this investigation would most likely cause: an increase in the gonial angle; downward repositioning of the midface; and a posterior displacement and expansion of the maxilla.
The carer's perspective: results of a survey of attitudes to dental care in 250 residential homes in Manchester
Authors: HOAD‐REDDICK G. , HEATH J.R.
Published: June 2007

A postal survey of 250 residential homes in the Manchester area was undertaken in late spring 1991. The 152 questionnaires returned gave information about 3757 residents. In spite of an apparently adequate understanding of the importance of dental care, carers did not appear to provide as effective a service as they thought necessary. Ninety‐one percent of carers realised dentures do not last indefinitely and 77.4% thought dentures should be checked every 2 years. Yet, in over 50% of homes, there was no provision for regular dental checks and in only 42.8% were residents seen every 2 years. It was pleasing to note that 70.7% of respondents welcomed the suggestion of a half‐day educational workshop. Suggestions are made for assisting homes with areas of particular concern. The importance of good rapport with local dental surgeons is stressed.
Solubility of irradiated rat molar teeth
Authors: WESCHLER Z. , GEDALIA I.
Published: June 2007

The solubility of molar teeth of rats exposed to irradiation and fluoridated drinking water was studied. Irradiation resulted in an increased molar enamel resistance enhanced by fluoridated drinking water.
Temporary prosthetic base materials: reproduction of surface detail
Authors: HEATH J.R. , BORU T.K. , GRANT A.A.
Published: June 2007

The baseplate material that best reproduced the most grooves in a gypsum cast was filled cold cure acrylic resin, followed in turn by modelling wax, grey shellac and finally the pink shellac material. These latter three thermoplastic materials performed best when softened in a water bath and subsequently adapted to a prewarmed cast.
Effect of loading and syringing on void formation in automixed addition silicone elastomers
Authors: CHONG Y.H. , SOH G. , LIM K.C.
Published: June 2007

The effect of loading and syringing on void formation in five automixed addition silicones was evaluated by determining the voids created in the first and second halves of material loaded and dispensed from a metal syringe. Impressions were made of a model with six stainless‐steel cylinders. The voids were counted at a predetermined site on 3 separate days using a binocular microscope at X 7 magnification. Automixed addition silicones did not confirm the ‘last out‐fewer bubbles’ phenomenon and specific loading and syringing technique did not appear to have a consistent effect on void formation in automixed elastomers.
A technique for treatment of extensive periodontal defects: a case study
Authors: GALGUT P.N.
Published: June 2007

This case study describes the use of oxidized cellulose mesh to improve healing of periodontal defects of poor regenerative capacity. Circumferential defects with horizontal bone loss were treated by surgical exposure of the root surface followed by scaling and root planing. Prior to flap replacement, oxidized cellulose mesh was positioned in incremental layers over the defects so as to replace the lost alveolar bone. It was to act also as a barrier to the ingress of epithlial cells and gingival fibroblasts into the healing wound using the principles vof guided tissue regeneration. Healing was good, with minimal post‐operative recession. Whether regeneration of alveolar bone and periodontal ligament occurred as a result of using this technique could not be determined in this clinical case study.
Masticatory electromyographic activity in healthy young adults and myogenous craniomandibular disorder patients
Authors: VISSER A. , McCARROLL R.S. , OOSTING J. , NAEIJE M.
Published: June 2007

The electromyographic (EMG) activity of the masseter and the anterior temporalis muscles were compared between 60 healthy controls and 61 myogenous craniomandibular disorder (CMD) patients. Subjects were asked to clench at 10% and at 50% of their maximum voluntary clenching level. The effects of CMD, age and gender were statistically analysed with the use of the analysis of covariance. The correlations between EMG asymmetries and the lateral slide from the retruded contact position to the intercuspal position and the asymmetry in the number of post‐canine tooth contacts between the left and the right side were investigated.

The CMD patients showed lower masseter EMG activities than the controls, whereas the anterior temporalis EMG activity was not different between the two groups. The activity index, relating the anterior temporalis EMG activity to the activity of the masseter muscles, confirmed the presence of a relatively high temporalis activity in the CMD group. No significant differences were found in the EMG asymmetries between the controls and the CMD patients. Males showed higher masticatory EMG activities than females. These gender effects were significant for the anterior temporalis at the 10% and 50% level and for the masseter muscle at the 10% level. The anterior temporalis EMG activity declined with age. No age related effects were observed in the masseter EMG. The lateral slide was larger and more prevalent in the CMD group. A significant correlation between the lateral slide and the anterior temporalis EMG was found for the CMD group at the 10% level. No correlation was found between the EMG asymmetry and the asymmetries in post‐canine tooth contacts.

In conclusion: significant CMD, age and gender effects were observed in the masticatory EMG activities of a group of myogenous CMD patients and a control group.
Symptomatology of patients with oligodontia
Authors: DER WEIDE Y. SCHALK‐VAN , BEEMER F.A. , FABER J.A.J. , BOSMAN F.
Published: June 2007

The aims of the present study were: (i) to identify the association of patterns of congenitally missing teeth with combinations of ectodermal symptoms occurring in patients with oligodontia; and (ii) to propose a diagnostic scheme for the general practitioner.

For this study 167 patients with oligodontia, both isolated and as part of a syndrome, and 135 healthy controls were interviewed and documented. Chi‐square tests, logistic regression and correspondence analysis were used to evaluate and test differences between the groups and associations between the congenitally missing teeth and ectodermal symptoms.

No significant differences were found between the control group and the patients with isolated oligodontia with exception of the skin. It could be concluded from the present study that there were no clear associations between congenitally missing teeth, either individually or patterns, and the ectodermal symptoms or combinations of ectodermal symptoms.

However, it could be concluded that if the most stable teeth are missing, or if the number of missing teeth is large the patient should be examined carefully for symptoms of ectodermal dysplasia.

Using logistic regression a patient could be classified as having isolated oligodontia or oligodontia as part of a syndrome with a specificity and sensitivity of 88.2%.
Incidence of temporomandibular joint disorders in patients seen at a hospital emergency room
Authors: LUZ J.G.C. , OLIVEIRA N.G.
Published: June 2007

A retrospective survey of a hospital emergency room population seen at an oral and maxillofacial surgery clinic during a 6‐month period found 62 patients (2.7% of the total population) with temporomandibular joint disorders. The diagnoses were myofascial pain‐dysfunction/temporomandibular joint dysfunction (MPD/TMJ) syndrome (70.9% of the cases) and dislocation (luxation) (22.5% of the cases).

The chief complaint was well defined in relation to the diagnoses: facial pain in the MPD/TMJ syndrome cases, and displacement of the mandible in the dislocation cases.
Bone augmentation using a synthetic bone graft in dogs
Authors: HÜRZELER M.B. , EINSELE F. , LEUPOLZ M. , SCHMITZ H.J. , STRUB J.R.
Published: June 2007

The aim of this investigation was to evaluate clinically and histologically the use of a synthetic bone graft (Ionogran®) alone and in combination with guided bone regeneration (GBR) for alveolar ridge augmentation. Five beagle dogs were used in this study. Prior to the augmentation procedure the maxillary and mandibular second, third and fourth premolars were extracted. Three months after the extractions, impressions from the area of the ridges were taken. Particles of Ionogran® were then placed under mucoperiosteal flaps in each quadrant. On the experimental sites, an expanded polytetrafluoroethylene barrier was placed between the flap and the particles. Impressions were retaken at 1 and 3 months after surgery. Three months after surgery, the animals were sacrificed and specimens were prepared for histological evaluation. Computer‐assisted volumetric analyses from the casts revealed an increase in ridge volume from baseline in both groups at 1 and 3 months. There was no difference in the height of the augmentation between the test and control sites. The histological results of this study indicate that this new synthetic bone graft appears to be a safe biocompatible grafting material. There were no apparent histological differences between the graft alone and graft/GBR sites. In both groups, however, graft particles were surrounded by dense fibrous connective tissue and bone formation was limited to the graft bone interface.