bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of lymph capillaries and blood capillaries in human temporomandibular joint discs
Authors: Yoshida H. , Fujita S. , Nishida M. , Iizuka T.
Published: March 2003

The localization of lymph capillaries and blood capillaries in the human temporomandibular joint (TMJ) discs was examined immunohistologically with anti‐human collagen IV antibody and anti‐human von Willebrand factor in 26 human TMJ samples. The 16 internal derangement cases were then compared with the 10 normal control cases. The findings suggested that blood capillaries scarcely existed in all the fields of normal control TMJ discs (5/270, 1·9%) nor did lymph capillaries exist in the normal TMJ discs (0/270, 0%). New growth of blood capillaries had localized in all fields of the internal derangement discs specimens (113/378, 29·9%) and was concentrated in the lower area of the posterior part of the discs. The authors also observed a small distribution of lymph capillaries in all fields of this material (17/378, 4·5%). The new growth of lymph capillaries were always related to the blood capillary distribution and therefore their presence might be directly related to the capillary proliferation.
The expression of transforming growth factor beta (TGF‐β) in the synovial membrane of human temporomandibular joint with internal derangement: a comparison with tenascin expression
Authors: Yoshida H. , Yoshida T. , Iizuka T. , Sakakura T. , Fujita S.
Published: March 2003

We examined the expression of the transforming growth factor beta (TGF‐β) in 28 human temporomandibular joint (TMJ) samples (internal derangement of TMJ and control specimens) by an immunohistological method using paraffin‐embedded tissues and a polyclonal antibody specific to human TGF‐β. The resulting reaction of TGF‐β expression divided into three types as follows. The first type, around the fibrocyte and in the lacunae of chondrocytes in the disc. The second type, at the stroma of the mildly hypertrophic synovial membrane and severely hypertrophic synovial membrane. The first type was observed in all the cases including the control cases. The second type showed only in the internal derangement of TMJ, and its expression pattern resembled that of tenascin (TN) within the stroma of hypertrophic synovial membranes. In conclusion, TGF‐β and TN were distributed in the affected synovial membrane of TMJ with internal derangement. These findings suggested that TGF‐β and TN might have a close relationship with synovitis, followed by tissue repair.
Size of the mandibular jaw angle related to age, tooth retention and gender
Authors: Ohm Elisabeth , Silness John
Published: March 2003

The size of the gonial angle was measured in cephalograms of 431 adults attending the Department of Prosthodontics, School of Dentistry, University of Bergen, Norway. The purpose of the work was to conduct a study of the variables often related to the development of the size of the gonial angle, i.e. age, degree of tooth retention, and gender. Descriptive data showed that the edentulous participants had the largest mean angle, the participants in possession of all teeth had the smallest angle, and the partially dentate participants had a jaw angle size between that of the aforementioned groups. Preliminary results of the analysis ( anova) showed that the number of teeth had a decisive influence on the size of the gonial angle. The correlation coefficients between size of the gonial angle and age showed that age explained approximately 8–16% of the variation of the angle through its relation with age. Sex differences in age and size of the gonial angle were not statistically significant in any of the three tooth retention categories. Future multiple regression analysis may explain a greater part of the variation of the angle if the analysis is carried out in separate age groups of the three categories.
Oral health status of patients 5–6 years after placement of cobalt–chromium removable partial dentures
Authors: Yeung A. L. P. , Lo E. C. M. , Chow T. W. , Clark R. K. F.
Published: March 2003

This study is a clinical survey of cobalt–chromium (Co–Cr) removable partial denture (RPD) wearers that aimed to investigate the effects of denture wearing on oral tissues. A random sample of patients who had received their dentures 5–6 years previously from a dental teaching hospital in Hong Kong was selected. Those who had been constantly wearing the RPDs were examined by one calibrated examiner under an optimal clinical setting. The patients’ dental, periodontal and mucosal status were assessed. A total of 87 patients were examined. Mucosal lesions under the Co–Cr RPDs were uncommon in this study sample. However, there was a high prevalence of plaque, gingivitis and gingival recession, especially in dento‐gingival surfaces in close proximity (within 3 mm) to the dentures. Thus, there is a special need for regular oral hygiene reinforcement, scaling and prophylaxis among RPD wearers. Despite a low caries incidence in the study sample, root caries were found to be associated with contact with the RPDs (P<0.05) but coronal caries were not. It is recommended that coverage of the exposed root surfaces by RPD components should be avoided. Also, topical fluorides should be regularly applied onto exposed root surfaces as a preventive measure.
Computer aided gnathosonic analysis: distinguishing between single and multiple tooth impact sounds
Authors: Prinz J. F.
Published: March 2003

Watt developed a classification of tooth contact sounds that distinguished between the short sharp, reproducible sounds heard when the teeth meet simultaneously and the dull prolonged, poorly reproducible sounds heard when tooth contacts are sequential. However, when a large occlusal prematurity, for instance a high restoration, is introduced, tooth contact sounds are also short sharp and highly reproducible. In this study, a method of distinguishing single from multiple tooth contact sounds is described, based on an analysis of the phase and amplitude of sounds detected by headphones placed over the ears.
Clinical rest and closest speech positions in the determination of occlusal vertical dimension
Authors: Burnett C. A.
Published: March 2003

Two subject groups had their mandibular positions determined, using an electrognathograph, at the clinical rest position (CRP) and at the closest speaking position (CSP). They were classified into a toothwear (largely of attritional origin) group (n=30) and a non‐toothwear, or normal, group (n=60). The mean CRP deduced for the groups was similar in all three dimensions and found to be just less than 2 mm open from and 0·6 mm posterior to intercuspal position (IP) and approximately in the midline. The CSP, in two dimensions, of the toothwear group was significantly closer to IP than that of the normal group. The vertical component of CRP and CSP was similar for the normal group but CSP was significantly reduced in comparison to CRP for the toothwear group. The most forward component of CSP was significantly more anteriorly placed than was that of CRP. Although there was a pronounced inter‐individual variation the results suggest toothwear, of long acting aetiology, has less affect on CRP than on CSP.
Thermal analysis on the cure speed of dual cured resin cements under porcelain inlays
Authors: Lee I. B. , Um C. M.
Published: March 2003

The reaction kinetics of five commercial dual cured resin cements (Bistite, Dual, Scotchbond, Duolink and Duo) were investigated when cured under varying thicknesses of porcelain inlays by chemical or light activation. The effect of the porcelain disc on the rate of polymerization of dual cured resin cement during light exposure was evaluated using thermal analysis, thermogravimetric analysis and differential scanning calorimetry. Inorganic filler weight %, the heat of cure (ΔH), the maximum rate of heat output and the peak heat flow time were measured when the polymerization reaction occurred by chemical cure only or by light exposure through 1, 2 and 4‐mm thick porcelain discs. In 4‐mm thick porcelain discs, the exposure time was varied from 40 to 60 s to investigate the effect of the exposure time on polymerization reaction. Cure speed by light exposure was 5–20 times faster than by chemical cure. The dual cured resin cements differed markedly in their sensitivity to light and chemical activation. The peak heat flow time increased by 1·51, 1·87 and 3·24 times as light cure was carried out through 1, 2 and 4‐mm thick porcelain discs, respectively. Exposure times recommended by the manufacturers were insufficient to compensate for the attenuation of light by the 4‐mm thick porcelain disc.
Relaxation rate in the assessment of masseter muscle fatigue
Authors: Lyons M. F. , Aggarwal A.
Published: March 2003

The aim of this study was to assess a simple method of measuring relaxation rate in the jaw‐closing system for the purpose of quantifying jaw muscle fatigue. A summary of the various different methods of measuring relaxation rate is also provided. The rates of twitch contraction and relaxation were measured in 30 symptom‐free subjects following bilateral direct electrical stimulation of the masseter muscles. The resulting twitch force was recorded via a force transducer placed between the anterior teeth. The transducer was held between the teeth with as little force as possible while four single stimuli were delivered at 5‐s intervals. The stimulating electrodes were then removed and replaced and the experiment was repeated. The force records of the resulting twitches were averaged and the half‐contraction time, twitch amplitude and half‐relaxation time were measured. There was a significant difference in half‐relaxation time between males and females, being faster in females (P=0·0045, independent t‐test). No significant difference was found in twitch amplitude and half‐contraction time between males and females. Half‐relaxation time and half‐contraction time were independent of twitch amplitude. This method of measuring the relaxation rate of the masseter muscles was found to be practical and the results were reproducible between sessions.
Heat‐cured acrylic resin repaired with microwave‐cured one: bond strength and surface texture
Authors: Rached R. N. , Del‐Bel Cury A. A.
Published: March 2003

This study evaluated the influence of chemical surface treatments in the repair strength of a heat‐cured acrylic resin (Lucitone 550, (LU)). A total of 70 specimens were made with LU according to American Dental Association (ADA) specification No. 12. Of these, 14 remained intact and were used as a control group (GI). A total of 56 specimens were selected randomly. These specimens were cut in the middle (10 mm), repaired with a microwave acrylic resin (Acron MC (AC)), and processed in a microwave oven for 3 min at 500 W. Prior to the repair, the surface of the cut ends received different chemical treatments (GIII = AC monomer dipping/30 s; GIV = acetone dipping/30 s; GV = acetone dipping/15 s + blast of air + AC monomer dipping/15 s; GVI = no wetting treatment). However, 14 intact specimens made with AC formed a second control group (GII). The effect of the chemical treatments on the surface texture of LU was observed with scanning electron microscopy. Flexural test results were submitted to paired t‐test and showed statistical differences (P < 0·05) only between the pairs GIV–GV and GIV–GVI. Strength mean values of repaired specimens were statistically lower (79–90%) than GII mean values. Strength mean values of GVI and GIV were 93 and 106%, respectively, of GI mean, showing no statistical differences. Scanning electron microscopic observations revealed various effects of the chemical treatments on the denture base resin surface. In conclusion, the wetting surface treatments affected the bond strength between the two acrylic resins, and no statistical differences in strength were observed between intact heat‐cured denture base material and the same material repaired with microwave acrylic resin.
Alteration of the angle of the coronoid process in prognathism
Authors: Yamaoka M. , Okafuji N. , Furusawa K. , Hasumi‐Nakayama Y. , Hayama H. , Yamada A. ‐S. , Kurihara S.
Published: March 2003

Muscles and bones may dynamically affect the functions of each other, resulting in changes in the activity of the muscle and/or morphological change in the bones. However, alterations of the morphology of the coronoid process have not been documented in relation to the temporal muscle between the mandible and the cranium. Angles of the coronoid process to the line through the right and the left frontotemporale were measured on posteroanterior (PA) cephalograms in patients with normal occlusions and Class II, division 1 malocclusions, and those with true skeletal Class III malocclusions. Standard deviation of the angle of the coronoid process in patients with Class III malocclusions was greater than those subjects with normal occlusion or Class II, division 1 malocclusions. Differences of angles between the right and the left coronoid process in each patient of either sex were significantly large in true skeletal Class III malocclusions (both P < 0·001). Large variation of angle of the coronoid process was related to prognathism, and this effect may represent adaptation of temporal muscle function to a variety of alterations in mandibular morphology.
Marginal adaptation of cast partial crowns made of pure titanium and a gold alloy under influence of a manual burnishing technique
Authors: Stoll R. , Makris P. , Stachniss V.
Published: March 2003

The aim of this study was to determine the marginal adaptation of partial crowns from pure titanium and a gold alloy after two different cementation techniques. Forty freshly extracted human molars were prepared and randomly divided in four groups. Two groups were restored with partial crowns using the gold alloy Degulor M®*. In one group, the crowns were fixed on the tooth by using a zinc phosphate cement. In the other group the margins were additionally burnished by using a hand burnisher† No. 660. In the other two groups, partial crowns from pure titanium were cemented in the same way. The marginal quality was determined by quantitative margin analysis in the SEM using a replica technique. Partial crowns from a gold alloy showed significantly (P < 0·05) more margin quality A (vertical marginal discrepancy <50 μm) while partial crowns from pure titanium had significantly (P < 0·05) more margin quality B (vertical marginal discrepancy 50–100 μm) and over‐extended margins (quality D). No significant (P < 0·05) difference was found between the conventional cementation technique and the technique with manual burnishing in both material groups.
Chewing ability as a parameter for evaluating the disability of patients with temporomandibular disorders
Authors: Kurita H. , Ohtsuka A. , Kurashina K. , Kopp S.
Published: March 2003

Restoration of chewing ability is an important aspect of the treatment for temporomandibular disorders (TMDs). However, too little attention has been paid to it. We have used a questionnaire to evaluate and score the chewing ability of TMD patients. The questionnaire includes 19 kinds of food and a chewing task. The patient was asked if she/he experiences difficulty in enjoying eating. The aim of this study was to evaluate correlations between score of chewing ability (SCA) and other symptoms/signs of TMD. Four hundred and seventy‐three consecutive TMD patients were evaluated for SCA and other symptoms/signs including temporomandibular joint (TMJ) pain, TMJ and muscle tenderness, TMJ noise (clicking and crepitus), and maximum mouth opening. The relationship between SCA and other symptoms/signs were analysed by multiple regression analysis. Score of chewing ability correlated significantly with TMJ pain and mouth opening capacity but not with TMJ noise and muscle tenderness. Age was a background factor but sex was not. The result of this study suggests that SCA correlated with dysfunction of the TMD patients. This method could be used to evaluate the ability of chewing in assessment of TMD.
Effect of curing with a plasma light on the properties of polymerizable dental restorative materials
Authors: Millar B. J. , Nicholson J. W.
Published: March 2003

Specimens of light‐curable dental restoratives have been prepared using either a conventional dental curing lamp (for 20 or 30 s) or a plasma light (for 1 or 2 s). The specimens were then stored in water until their mass equilibrated, then dried to constant mass. Most specimens lost material in this process but the losses in all specimens cured with the plasma light were significantly greater than those cured with the conventional lights (P < 0·05). Longer cure times gave slightly reduced losses in water in most cases. The specimens were then returned to water and allowed to re‐equilibrate and their equilibrium water uptake determined. There was no simple trend in this latter property because elution of loosely bound hydrophilic species may have resulted in a less hydrophilic specimen, whose equilbrium water content was therefore correspondingly lower. Overall, the losses through dissolution in water suggest that plasma curing is less effective for these materials than conventional light curing, as it probably results in material with lower molar mass. The losses for the resin‐modified glass–ionomer were much greater than for other materials, and it was concluded that the more rapid polymerization with plasma light caused a significant inhibitation of the acid‐base part of the setting process. These findings suggest that long‐term durability of materials may be compromised by employing plasma light cure rather than a conventional cure system and further studies of this point are recommended.
Quantitative description of temporomandibular joint sounds: defining clicking, popping, egg shell crackling and footsteps on gravel
Authors: Leader J. K. , Robert Boston J. , Rudy T. E. , Greco C. M. , Zaki H. S. , Henteleff H. B.
Published: March 2003

This study presents a quantitative description of tempromandibular joint (TMJ) sounds provided by a rule‐based classification system based on sound classification by three dentists, who listened to and classified the sound recordings as no sound, click, coarse crepitus and fine crepitus. The sounds were recorded with microphones in the ear canal from 126 subjects during vertical opening, digitized at 15 000 Hz, and replayed using a computer sound card and speakers. The dentists’ classification of a test set resulted in intra‐ and inter‐tester j values ranging from 0·71 to 0·81 and 0·61–0·73, respectively. Pooled j values for the dentists and the dentists plus the rules were 0·67 and 0·58, respectively, which were not significantly different in terms of the sound features on which the rules were based (P = 0·13). Linear discriminant analysis showed the four TMJ sound types were significantly different (P < 0·001). The performance of the rules was equivalent to the dentists and marginally better than the linear discriminant functions (P = 0·08), establishing the validity of the quantitative descriptions they provide. The recording and rebroadcast methodology produced sounds very similar to those observed in the clinic and could be used to train clinicians in classifying TMJ sounds.
Prediction of demand for treatment of temporomandibular disorders
Authors: Kirveskari P.
Published: March 2003

Baseline (BL) data on signs and symptoms characteristic of temporomandibular disorders (TMDs) were analysed in 67 young non‐patients participating as controls in a clinical trial. Data on the incidence of demand for treatment of TMD were collected during the 4‐year follow‐up period, and, by means of a mailed questionnaire, during an additional 2 years. The variables analysed included palpation and auscultation of the joints, palpation of the muscles of mastication, experience of joint sounds, of pain on jaw movements, of ear symptoms, awareness of a clenching habit, and frequency of headache. A present–absent dichotomy was applied throughout. Palpation tenderness of masticatory muscles was significantly (P=0·02) more often present at BL in those who subsequently requested treatment than in those who did not. The same was true of the combination of palpatory tenderness and clenching habit (P=0·007), whereas the clenching habit alone failed to show a significant difference (P=0·06). However, the predictive values remained too low to be clinically useful, with a possible exception of the negative predictive value of muscle tenderness. The findings indicate that the variables conventionally used to describe the functional status of the masticatory system are at best of modest value in the estimation of individual risk of TMD in healthy young subjects.
Oral health care status of homebound elderly in Japan
Authors: Morishita Masayuki , Takaesu Yoshinori , Miyatake Kokichi , Shinsho Fumiaki , Fujioka Michiharu
Published: March 2003

We examined the present conditions of oral health care in order to contribute towards an effective system to provide oral health care for homebound elderly in Japan. A questionnaire was mailed to homebound elderly subjects (n=908) and returned by mail. A 73·6% response was achieved. The questionnaire was designed to elicit information with respect to the general condition of the subjects and independence of oral health care. About 70% of the subjects were chair‐ or bed‐bound. Among all subjects, 37·6% required partial or full assistance on toothbrushing, 55·6% on cleaning dentures and 46·7% on eating. The degree of oral health care tended to be poor for chair‐ or bed‐bound elderly compared with independent or house‐bound elderly. Homebound elderly with lower Activities of Daily Living Scale (ADL) required more support for oral health care compared with elderly with higher ADL.
Effect of gutta‐percha solvents at different temperatures on the calcium, phosphorus and magnesium levels of human root dentin
Authors: Doğan H. , Taşman F. , Çehreli̇ Z. C.
Published: March 2003

The aim of this study in vitro investigation was to evaluate the alterations caused by warmed gutta‐percha solvents on the calcium, phosphorus and magnesium levels of root dentin. Extracted human anterior teeth, whose crowns and apical root thirds had been removed were used as root dentin specimens. The roots were sectioned longitudinally into two segments, cleaned and dried. Segments were divided into 12 groups (n=12). In 6 groups, the specimens received treatment with the following solvents at room temperature (22 °C): Chloroform, xylene, eucalyptol, orange oil, halothane and saline (control). Within each group, the specimens were further subgrouped into two to be incubated (100% humidity at 37 °C) for 5 and 10 min, respectively, following treatment with the solvents. The remaining six groups were treated with the same solvents which had been previously warmed to body temperature (37 °C) and received the same experimental procedures. The levels of calcium, phosphorus and magnesium in each specimen were analysed using energy dispersive spectrometric microanalysis. Statistical analysis of the readings showed that neither warming of the solvents nor prolonged incubation (treatment) time was capable of altering the histochemical composition of cut root dentin surfaces.
Dentine hypersensitivity in subjects recruited for clinical trials: clinical evaluation, prevalence and intra‐oral distribution
Authors: Gillam D. G. , Aris A. , Bulman J. S. , Newman H. N. , Ley F.
Published: March 2003

Relatively few studies have reported on the frequency, distribution and severity of dentine hypersensitivity (DH) in subjects recruited for clinical trials of desensitizing agents. Potential subjects (n= 48 M, 81 F, mean age 35·1 years) for inclusion into such a study were screened to determine the extent of the problem. 117 subjects (41 M, 76 F) mean age 24·9 years were clinically examined. Evaluation by questionnaire indicated that the prevalence of DH was proportionately higher in the 20–29·9 years (34·9%), and 30–39·9 years groups (33·3%), respectively. Sensitivity to cold was the main presenting symptom. Tactile (probe) and cold air (dental air syringe) stimuli were used to clinically evaluate DH. Of the teeth eligible for evaluation 1561/3136 (49·8%) responded to either one or both of the test stimuli; 274/3136 (8·7%) responded to tactile only stimulation, 779/3136 (24·8%) to thermal only stimulation and 508/3136 (16·2%) to both tactile and thermal stimulation. Of those teeth responding to the stimuli, 477 (30·6%) were premolars, 437 (28%) incisors, 415 (26·8%) molars and 232 (14·9%) canines. The results agree with those of previously reported studies in that DH is most frequently observed on premolars and that proportionately more teeth are sensitive to evaporative than to tactile stimulation. Furthermore it would appear from the results of the study that tactile is less effective than thermal/evaporative stimulation in the evaluation of DH.
Occlusal contact area (OCA) wear of two new composite restoratives
Authors: Yap A. U. J.
Published: March 2003

The occlusal contact area wear resistance of two new composite restoratives (Z250 and P60) was investigated and compared with two existing materials (Silux and Z100) using a reciprocal compression‐sliding test apparatus. Six wear specimens were made for each material and subjected to wear testing at 20 MPa with artificial saliva as lubricant. Wear depth (μm) was measured using profilometry every 20 000 cycles up to 120 000 cycles. Results were analysed using ANOVA/Scheffe’s test (P < 0·05) and Pearson’s correlation. The effects of cyclic loading on wear and counter‐body loss were material dependent. Silux had the lowest wear at all cyclic intervals. At 20 000 and 40 000 cycles, Silux had significantly less wear than all the other composites evaluated, and Z100 had significantly less wear than Z250 and P60. After 60 000 cycles, significant differences in wear was observed only between Silux and the other composites. Correlation between number of cycles and wear/counter‐body loss, and between wear and counter‐body were significant and positive. The microfilled composite Silux had significantly better OCA wear resistance than the minifilled composites Z100, Z250 and P60.
The effect of physiotherapy on post‐temporomandibular joint surgery patients
Authors: Oh D. W. , Kim K. S. , Lee G. W.
Published: March 2003

The purpose of this study was to investigate the effect of physiotherapy on rehabilitation of patients who had temporomandibular joint (TMJ) surgery. The treatment group consisted of 22 post‐surgical patients who were treated with physiotherapy, and the non‐treatment group consisted of 22 post‐surgical patients who received no physiotherapy. The assessment tools were made using visual analogue scale (VAS) and craniomandibular index (CMI) which consisted of dysfunction index (DI) and palpation index (PI). All patients received follow‐up for 7 months. The subjects were measured three times; before surgery, 6 weeks after surgery and 7 months after surgery. On the 6 week post‐surgery assessment, DI and total CMI scores of the treatment group were significantly lower (P < 0·05) than those of the non‐treatment group. On the assessment performed 7 months after surgery, all variables were significantly lower (P < 0·05) for the treatment group compared with those of the non‐treatment group. The findings of the study indicate that physiotherapy has a positive effect in relieving pain and restoring TMJ function after surgery.
Enamel tensile bond strength and morphology of resin–enamel interface created by acid etching system with or without moisture and self‐etching priming system
Authors: Torii Y. , Itou K. , Hikasa R. , Iwata S. , Nishitani Y.
Published: March 2003

The purpose of this study was to estimate the effect of three types of different adhesive systems on enamel adhesion. Scotchbond Multi‐Purpose (MP) as a traditional system, Single Bond (SB) as a wet‐bonding system and Clearfil SE Bond (SE) and Unifil Bond (UB) as self‐etching priming systems were used. Bovine enamel was treated with each system and tensile bond strength (TBS) of resin to the enamel was measured. The conditioned enamel surfaces and resin–enamel interfaces were also morphologically observed with scanning electron microscope (SEM). The mean TBS for MP, SB, SE and UB were 15·3, 13·7, 14·3 and 11·6 MPa, respectively. There was no significant difference in mean TBS among all products but the traditional system showed the most stable TBS. In SEM observations, self‐etching primer created a weaker etched pattern on the enamel surface than phosphoric acid. At the resin–enamel interfaces, thick tag‐like extensions penetrated into the enamel etched with phosphoric acid regardless of using the wet‐bonding technique, while self‐etching primer created thin lamina‐like resin penetrations. These results indicate that the traditional system with phosphoric acid etching exhibits the most stable enamel adhesion although the enamel‐bonding promoting abilities of these adhesive systems are equivalent to each other.
Dynamic influence of food consistency on the masticatory motion
Authors: Filipić S. , Keros J.
Published: March 2003

The masticatory cycle is a complex process and it depends on many factors. In our study we wanted to prove to what extent various types of food consistency influence the masticatory motions, especially the extent of forward, downward and lateral motions of the mandible. Nineteen study subjects aged from 20 to 37 years and with intact teeth rows were asked to chew three types of food of various consistency (banana, bread and carrot). The motions of the mandible were recorded by stereo‐photo‐grametric system. Study results have shown that in all 19 study subjects the increase in food consistency increases the extent of masticatory motions. The average size of forward mandibular motion in all 19 study subjects when chewing banana amounts to 2·65 mm, when chewing bread it is 2·96 mm and 3·64 mm when chewing carrot. The average size of downward mandibular motion for all 19 study subjects amounts to 6·79 mm when chewing banana, 7·17 mm when chewing bread and 8·09 mm when chewing carrot. The average size of lateral mandibular motion in all 19 study subjects amounts to 2·46 mm when chewing banana, 2·80 mm when chewing bread and 3·40 mm when chewing carrot. Although varying from subject to subject, the masticatory cycle significantly depends on food consistency. By increasing the consistency of a mouthful, the extent of mandibular motion increases in every single study subject.
Local kinematic and anthropometric factors related to the maximum mouth opening in healthy individuals
Authors: Naeije M.
Published: March 2003

The aim of the present study was to investigate the influence of local anthropometric (mandibular length and width) and kinematic (forward and downward condylar translation and angle of rotation) variables upon the maximum mouth opening (MMO). Thirty‐five healthy individuals, 17 men and 18 women, mean age 23 years with a range from 18 to 31 years, performed six to eight maximal, symmetrical and pain‐free open‐close movements during a 20‐s recording. Mandibular movements were recorded by means of the OKAS‐3D jaw movement recording system. A stepwise regression analysis showed that differences in MMO are mainly explained by differences in the angle of rotation and in mandibular length (R2adj=91·5%). Including the downward and forward component of condylar translation into the regression model increased the explained variance with only 4·7%. A second stepwise analysis showed that the angle of rotation is positively related to the forward component of the condylar translation and negatively related to its downward component (R2adj=52·7%). In conclusion, differences in MMO between healthy individuals are, to a large extent, explained by differences in the angle of rotation and in mandibular length. In its turn, differences in the angle of rotation are related to differences in condylar translation.
Effect of storage media upon the surface micromorphology of resin‐based restorative materials
Authors: TURSSI C. P. , HARA A. T. , SERRA M. C. , RODRIGUES A. L.
Published: March 2003

Summary The aim of this study was to evaluate the effect of different storage media upon the surface micromorphology of resin‐based restoratives. One resin‐modified glass–ionomer (Fuji II LC Improved), one polyacid‐modified composite resin (Dyract AP), one microfilled composite resin (Durafill VS), and one hybrid composite resin (Filtek Z250) were tested. For each material, 45 standardized cylindrical specimens were randomly made. After 24 h, samples were finished and polished, and their surface roughness measured to obtain Ra (μm) baseline values (Bv). Fifteen specimens of each material were then stored at 37 ± 1 °C, for 24 h, either in distilled deionized water or in artificial saliva, or else subjected to a pH‐cycling regimen. At the end of 10 days of storage, final readings (Fv) of surface roughness were obtained. The Analysis of Covariance (α=0·05), considering the covariate Bv showed a significant interaction between restorative materials and storage media (Pvalue=0·0000). Multiple comparison Tukey's test revealed that the surface roughness of resin‐based restoratives subjected to a pH‐cycling model was significantly higher compared with both distilled deionized water and artificial saliva. Micromorphological changes were noticed in a situation of acid challenge.
The determination of freeway space using two different methods
Authors: Johnson A. , Wildgoose D. G. , Wood D. J.
Published: March 2003

summary  The aim of this study was to determine the average freeway space of dentate subjects and relate this to recommended ranges for edentulous patients, also to see if any differences were observed between two different methods of measuring freeway space. The freeway space of 72 dentate subjects was measured, first using a Willis gauge, and secondly using a pair of sprung dividers. The intra‐ and interoperator variability was evaluated as was the reproducibility of the accuracy of both techniques. The mean freeway space using the Willis gauge was 3·3 mm, for both intra and inter operator variability, and with the sprung dividers 3·1 and 2·9 mm, respectively, with no significant difference being seen between any combination of results (P > 0·05). Individual measurements within the two measuring methods being assessed showed significant differences (P < 0·05). The mean measurements of freeway space in dentate subjects found in this study were within the recommended 2–4 mm range, however, 15% of the subjects in the study had freeway space measurements outside this range. This study would suggest that the range for freeway space measurement could more realistically be 2–7 mm.
The evaluation of the removal forces on the conus crowned telescopic prostheses with the finite element analysis (FEA)
Authors: Güngör M. A. , Artunç C. , Sonugelen M. , Toparli M.
Published: March 2003

SUMMARY  The removable partial dentures supported by the telescopic crowns are an alternative for directly retained removable partial dentures. The stress distribution on the retainers and the surrounding tissues created by the telescopic and conus crowns of different sizes (4, 5, 6 mm) and taper (0°, 2°, 4°, 6°) was investigated with the finite element analysis (FEA) method. The stress values obtained were evaluated either as strain or tensional forces. The loosening force of the secondary crown being determined as 5 N, the increase in tension of the dentine, metal structure, alveolar bone, periodontal ligament and the pulp were determined by the increasing height and taper. The reason for the increase in tensional forces with increasing taper was the result of the constant loosening force of 5 N applied in all experimental models. The strain was more effective than the tension with the highest stress being in the cervical region of the metal structure. The aim of this study was to determine the force exerted on the teeth and surrounding tissues by the loosened secondary crown.
Secondary caries susceptibility of teeth with long‐term performing composite restorations
Authors: Rezwani‐Kaminski T. , Kamann W. , Gaengler P.
Published: March 2003

summary The aim of this study was to assess retrospectively the caries susceptibility of posterior teeth with composite restorations after 18 and 20 years. The sample was selected out of the recall of a dental office. Sixteen restorations were reassessed after 18 and 20 years. All findings have been rated according to the C criteria of the CPM index. For the micromorphological evaluation with SEM, replicas were made using a two‐step impression technique. All restorations demonstrated marginal imperfections and a predominant rough surface. At the 18 year‐evaluation two restorations exhibited secondary caries. Despite of extended marginal gap formations none of the 12 restorations reexamined at 20 years showed secondary caries. Direct composite restorations can serve over a long period of time despite of poor qualitative parameters. Micromorphological marginal deterioration and clinical gap formation do not necessarily result in a higher risk for secondary caries.
Comparison of flexural properties of composite restoratives using the ISO and mini‐flexural tests
Authors: Yap A. U. J. , Teoh S. H.
Published: March 2003

summary  The purpose of this study was to investigate the flexural properties (flexural strength and flexural modulus) of four commercial composite restoratives (Silux Plus, Z100, Ariston and Surefil) using the ISO 4049 flexural test (IFT) and a mini‐flexural test (MFT). Both tests involved the use of three‐point loading and the same fixture. The difference between the tests was in the length of the composites specimens and the distance between the supports [20 mm (IFT) and 10 mm (MFT)]. Six specimens were made for each material and flexural test. Test specimens [25 × 2 × 2 mm (IFT) and 12 × 2 × 2 mm (MFT)] were fabricated according to manufacturers' recommendations. After light‐polymerization, the specimens were stored in distilled water at 37 °C for 24 h. The specimens were subsequently blotted dry, measured and subjected to flexural testing using an Instron Universal Testing Machine with a crosshead speed of 0·75 mm min−1. Data was analysed using anova/Scheffe's, paired samples test (P < 0·05) and Pearson's correlation (P < 0·01). For both IFT and MFT, results of statistical analysis of flexural strength were identical. Silux had significantly lower flexural strength compared with the other composites and the flexural strength of Ariston was significantly lower than Z100 and Surefil. For IFT, the flexural modulus of Z100 was significantly higher than Silux, Ariston and Surefil while for MFT, Silux had significantly lower modulus compared with Z100, Ariston and Surefil. A significant, strong and positive correlation (r=0·95) was observed for flexural strength between IFT and MFT. Correlation for flexural modulus was also significant and positive but was weaker (r=0·53). As MFT has the advantage of ease of specimen fabrication and is more clinically realistic, it is suggested for the testing of composite restoratives. Clinical relevance The mini‐flexural test may be better than the ISO flexural test for screening of composite restoratives for clinical applications.
Physico‐mechanical properties of a fast‐set highly viscous GIC restorative
Authors: Yap A. U. J. , Pek Y. S. , Cheang P.
Published: March 2003

summary  The fast‐setting reaction of ‘fast‐set’ highly viscous glass–ionomer cements (GIC) may result in superior mechanical properties and good wear resistance as the material can theoretically achieve sufficient strength to resist masticatory loads within a shorter time. The aim of this study was to determine the hardness, strength (compressive and diametral tensile) and wear resistance of a ‘fast‐set’ highly viscous GIC (Fuji IX GP Fast). Its regular set counterpart (Fuji IX GP) was used for comparison. The glass powders of the two cements were also characterized. Hardness testing [Vickers' hardness number (VHN)] was performed with a digital hardness tester (load=50 g; dwell time=30 s) and compressive/diametral tensile strength testing (MPa) was conducted based upon British Standards specification for GICs (BS6039, 1981). Wear testing was conducted using a reciprocal compression‐sliding wear instrumentation at 20 MPa contact stress against SS304 counter‐bodies with distilled water as lubricant. All specimens were immersed in distilled water at 37 °C and tested 24 h after start of mixing. Further mechanical tests (hardness and strength) were conducted with specimens stored for 1 week in distilled water at 37 °C. The glass powders were characterized using laser particle sizing, standard electron microscope (SEM) and energy dispressure X‐ray (EDX) analysis. Results were analysed using multiple analysis of variance (manova) and independent samples t‐test at significance level 0·05. No significant difference in hardness, compressive and diametral tensile strength was observed between Fuji IX GP and Fuji IX GP Fast at 1 day. There was also no significant difference in wear at all cyclic intervals. Although the difference in strength was not significant between the two cements at 1 week, Fuji IX GP Fast was significantly harder than Fuji IX GP. Particle size of both cements ranged from 0·3 to 200 μm. The mean particle sizes were, however, different and were 13·43 and 7·13 μm for Fuji IX GP and Fuji IX GP Fast, respectively. Fuji IX GP Fast offers no other advantage over Fuji IX GP with the exception of improved hardness. Clinical relevance Besides being harder, the fast‐set highly viscous GIC restorative offers no other physico‐mechanical advantage over its regular set counterpart.
Changes in surface roughness and colour stability of soft denture lining materials caused by denture cleansers
Authors: Jin C. , Nikawa H. , Makihira S. , Hamada T. , Furukawa M. , Murata H.
Published: March 2003

summary  Soft denture lining materials were immersed into solutions of denture cleansers for 8 h at room temperature, and immersed into distilled water for the remainder of the 24‐h period at 37 °C. Surface roughness of the soft denture lining materials was measured by contact type surface roughness instrument. For the colour stability test, soft denture lining materials were immersed in the denture cleansers as described above for 180 days. Finally, the colour changes of each material were quantitatively measured by a photometrical instrument to obtain the colour differences between newly processed specimen and immersed specimens (P < 0·01). An autopolymerizing silicone material, Evatouch, exhibited severe changes in surface roughness by all denture cleanser, and the generic material GC Denture Relining showed the minimal changes. Severe colour changes were also observed with some liner and cleanser combinations (P < 0·01). Except for Evatouth, the four silicone soft liners were more stable in surface roughness and in colour change than the two acrylic soft liners. One autopolymerizing silicone (GC denture relining) and one heat curing silicone (Molloplast B) demonstrated the best stability.
The effect of custom tray material type and fabrication technique on tensile bond strength of impression material adhesive systems
Authors: Abdullah M. A. , Talic Y. F.
Published: March 2003

summary  The purpose of this investigation was to evaluate the tensile bond strengths of two impression material systems (polysulphide and polyvinyl siloxane) to two custom tray materials [autopolymerizing and visible light‐cured (VLC) acrylic resin]. The effect of polymerizing the tray materials directly against wax spacer and tinfoil was evaluated for each material. Polymerizing tray materials against tinfoil significantly increased the bond strengths of polysulphide and polyvinyl siloxane impression materials to VLC and autopolymerizing acrylic resin tray materials. Polyvinyl siloxane VLC cured against tinfoil combination produced the strongest bond. The VLC resin tray material generated greater bond strength than autopolymerizing acrylic resin when polymerized against tinfoil.
Biofilm formation of Candida albicans on the surfaces of deteriorated soft denture lining materials caused by denture cleansers in vitro
Authors: Nikawa H. , Jin C. , Makihira S. , Egusa H. , Hamada T. , Kumagai H.
Published: March 2003

summary  Candidal colonization and subsequent biofilm formation on denture materials are important in the development of pathogenesis, such as denture stomatitis. Routine use of denture cleansers is one of the most effective methods of denture plaque control, although the incompatibility of soft liners and denture cleansers cause damage to the materials. The present study, biofilm formation of Candida albicans on the surfaces of soft denture lining materials, immersed in denture cleansers for 180 days were studied. Seven commercially available soft denture lining materials, were artificially deteriorated by immersion into three commercially available denture cleansers for 180 days, and subsequent fungal growth and biofilm formation were studied by measuring pH of the media and by the use of adenosine triphosphate (ATP) analysis. Fungal biofilm formation on the deteriorated soft liners varied depending upon the combination of the soft liners and denture cleansers. Several combinations of soft liners with denture cleansers exhibited the significantly high colonization capacity as compared with each sample immersed in distilled water, used as individual controls. The relationship between the biofilm formation on the samples of each material and the surface roughness of the soft lining materials was analyzed. However, no significant correlation was observed. The results, taken together, suggested that fungal colonization could be predominantly regulated by the combination of lining material with denture cleansers. In clinical terms, our findings suggests that daily cleansing of soft lining materials with mismatched denture cleansers promoted the subsequent biofilm formation of fungi on the materials.
The influence of war stress on the prevalence of signs and symptoms of temporomandibular disorders
Authors: Uhač I. , Kovač Z. , Valentić‐Peruzović M. , Juretić M. , Moro L. J. , Gržić R.
Published: March 2003

summary  The aim of this study was to determine the prevalence of signs and symptoms of temporomandibular disorders in patients with post‐traumatic stress disorder (PTSD) occurring as a consequence of exposure to war stress. The examined group consisted of 100 male subjects, aged from 25 to 50 years, who had taken part in the War in Croatia, and in whom PTSD had previously been diagnosed. The control group comprised 100 subjects, without PTSD, of the same sex and age group, who had not taken part in the War. A functional evaluation of the stomatognathic system was performed using the Helkimo Anamnestic and Clinical Dysfunction Index.

Eighty‐two per cent of the group with PTSD had at least one symptom, and 98% at least one sign of dysfunction. Eight per cent reported mild symptoms and 74% severe symptoms. Twenty‐eight per cent showed mild clinical signs, 22% had signs of moderate, and 48% of severe dysfunction.

Twenty‐four per cent of the control group of subjects had at least one symptom, and 52% at least one clinical sign of dysfunction. Twenty‐two per cent reported mild and 2% severe symptoms. Mild clinical signs of dysfunction were found in 50% of subjects in the control group, moderate in 2% and none exhibited severe clinical signs. It is concluded that correlation exists between war stress and temporomandibular disorders.