bluuebunny/crossref_metadata_2025 huggingface dataset:
Processing of Frameshifted Vasopressin Precursors
Authors: Evans  , De Bree  , Nijenhuis  , Van der Kleij  , Zalm  , Korteweg  , Van Leeuwen  , Burbach
Published: March 2003

Biosynthesis of the vasopressin (VP) prohormone in magnocellular neurones of the hypothalamo‐neurohypophysial system comprises endoplasmic reticulum (ER) transit, sorting into the regulated secretory pathway and subsequent processing in the individual proteins VP, neurophysin and a glycoprotein. These processes are severely disrupted in the homozygous diabetes insipidus (di/di) Brattleboro rat, which expresses a mutant VP precursor due to a single nucleotide deletion in the neurophysin region of the VP gene resulting in VP deficiency. Previous studies have shown the presence of additional frameshift mutations in VP transcripts, in solitary magnocellular neurones of the di/di rat due to a GA dinucleotide deletion resulting in two different mutant VP precursors with partly restored reading frame. Frameshifted VP precursors are also expressed in several magnocellular neurones in wild‐type rats. In this study, we determined if the +1 frameshifted precursors from di/di and wild‐type rats can lead to biosynthesis of the hormone VP. Therefore, eukaryotic expression plasmids containing the frameshifted VP cDNAs were transiently expressed in peptidergic tumour cell lines, and cells were analysed by reversed phase high‐performance liquid chromatography and specific radioimmunoassays, and by immunofluoresence. Neuro2A neuroblastoma cells expressing the +1 frameshifted precursors of di/di rats retained products in the cell body. Only precursor or insignificant quantities of neurophysin‐immunoreactive products were detected. In contrast, in AtT20 cells, frameshifted VP precursors were at least partly processed to yield the VP peptide, indicating that they have access to the regulated secretory pathway. Comparison between the two cell lines showed a very slow ER transit of the wild‐type prohormone combined with inefficient processing in Neuro2A cells. The results show that mutant precursors can reach the regulated secretory pathway if ER transport is sufficiently rapid as in the case of AtT20 cells. This suggests that the di/di rat may regain the capacity to biosynthesize authentic VP through these +1 frameshifted precursors in magnocellular neurones.
Effects of Orexins on the Hypothalamic‐Pituitary‐Adrenal System
Authors: Jászberényi M. , Bujdosó E. , Pataki I. , Telegdy G.
Published: March 2003

The effects of the recently identified neuropeptides orexin‐A and orexin‐B on the hypothalamic‐pituitary‐adrenal (HPA) system were investigated. An in vivo system was used to assess the central effects of both orexin‐A and orexin‐B. Different doses of the orexins (2.8–560 pmol) were administered intracerebroventricularly (i.c.v.) to adult male rats, and plasma corticosterone was used as an index of the degree of the activation of the HPA system. Both peptides exhibited a clear dose–response action, although orexin‐B proved to be less effective than orexin‐A. Pretreatment with the corticotropin‐releasing hormone (CRH) antagonist α‐helical CRH9−41 completely prevented the action of the orexins. Orexin‐A, orexin‐B or adrenocorticotropic hormone (ACTH) was further administered intraperitoneally (i.p.). While ACTH evoked a significant adrenal response, the orexins did not influence the basal secretion. Adrenal slices, oxygenized and perifused with Krebs' solution, were also treated with orexin‐A, orexin‐B or ACTH. Both orexins failed to modify the release of corticosterone, but ACTH induced a marked adrenal response. This study suggests that these appetite‐regulating peptides might activate the HPA system at a central level but neither orexin‐A nor orexin‐B appears to modulate directly the adrenal corticosterone release.
Angiotensin II Induces Inward Currents in Subfornical Organ Neurones of Rats
Authors: Ono K. , Honda E. , Inenaga K.
Published: March 2003

The action of angiotensin II on subfornical organ (SFO) neurones was studied using whole‐cell current and voltage‐clamp recordings in rat slice preparations. In the current‐clamp mode, membrane depolarization in response to angiotensin II was accompanied by an increased frequency of action potentials and an increased membrane conductance. In the voltage‐clamp mode, angiotensin II elicited inward currents in a dose‐dependent manner. The net angiotensin II‐induced inward currents were voltage‐independent, with a mean reversal potential of −29.8 ± 6.2 mV. Amplitudes of the angiotensin II‐induced inward currents were decreased during perfusion with a low sodium medium. The angiotensin II‐induced inward currents were blocked by the AT1 antagonist losartan, and were partially blocked by the AT2 antagonist PD‐123319. Neurones which were sensitive to angiotensin II were found in the peripheral region of the SFO, whereas neurones in the central region were less sensitive to angiotensin II. These results suggest that angiotensin II induces inward currents, with opening of nonselective cation channels through mainly AT1 receptors in a subpopulation of SFO neurones of rats.
Large Reduction in the Number of Galanin‐Immunoreactive Cells in Pancreatic Islets of Diabetic Rats
Authors: Adeghate E. , Ponery A. S.
Published: March 2003

Although galanin has been shown to be present in pancreatic islet cells, there is no literature available on the pattern of distribution and the effect of galanin in the pancreas of diabetic animals or human models. The aim of this study was to examine whether galanin immunoreactivity changes after the onset of diabetes mellitus in the rat model. The present study used immunohistochemical techniques to examine the pattern of distribution of galanin–like immunoreactive cells in the pancreas of rats with streptozotocin‐induced diabetes. The effect of galanin on insulin secretion from intact rat pancreatic tissue fragments was also investigated using a radioimmunoassay technique. Numerous galanin–like immunoreactive cells were observed in both the peripheral and central regions of the islet of Langerhans of normal rat pancreas. By contrast, the islets of diabetic rat pancreas contained significantly (P < 0.0001) fewer galanin–like immunoreactive cells than nondiabetic rats. Galanin was colocalized with insulin in the islets of normal and diabetic rats. Galanin had an inhibitory effect on insulin secretion from the isolated pancreatic tissue fragments of normal and diabetic rats at all concentrations (10−12 to 10−6 M) employed. Galanin at 10−9 M caused a significant (P < 0.02) decrease in insulin secretion from normal rat pancreatic tissue fragments compared to basal. These observations indicate that galanin may play a significant role in the regulation of insulin secretion.
Leptin Regulation of Agrp and Npy mRNA in the Rat Hypothalamus
Authors: Korner J. , Savontaus E. , Chua S. C. , Leibel R. L. , Wardlaw S. L.
Published: March 2003

Agouti‐related protein (AGRP) is synthesized in the same neurones in the arcuate nucleus as neuropeptide Y (NPY), another potent orexigenic peptide. AGRP antagonizes the action of α‐melanocyte stimulating hormone, a derivative of pro‐opiomelanocortin (POMC) at the hypothalamic MC4 receptor to increase food intake. Although leptin has been shown to regulate Agrp/Npy and Pomc‐expressing neurones, there are differences with respect to Agrp regulation in leptin receptor‐deficient mice and rats. Unlike the obese leptin receptor‐deficient db/db mouse, which exhibits upregulation of Agrp mRNA expression in the medial basal hypothalamus (MBH) compared to lean controls, the obese leptin receptor‐deficient (faf; Koletsky) rat does not exhibit upregulation of Agrp expression. To determine whether this represents a general difference between leptin receptor‐deficient mice and rats, neuropeptide gene expression was analysed in the MBH of lean and obese rats segregating for a different leptin receptor mutation, Leprfa (Zucker). Fasting in lean rats (+/fa) for 72 h significantly increased Agrp and Npy mRNA expression, and decreased Pomc mRNA expression as detected by a sensitive solution hybridization/S1 nuclease protection assay. Npy mRNA levels were significantly increased in fed obese fa/fa compared to lean rats, and further increased in the obese animals after fasting. In contrast, Agrp mRNA levels did not differ between fed lean and fed obese rats, and fasting did not significantly change Agrp levels in obese rats. To determine whether the change in Agrp expression that occurs with food deprivation in lean rats could be prevented by leptin replacement, Sprague‐Dawley rats were fasted and infused via subcutaneous osmotic micropumps for 48 h with either saline or recombinant mouse leptin. Fasting significantly increased Agrp and Npy, and decreased Pomc mRNA levels. Leptin infusion almost completely reversed these changes such that there was no significant difference between the levels in the fasted rats and those that were fed ad libitum. Thus, in fasted lean rats, Agrp and Npy are upregulated in parallel when leptin levels fall and are downregulated by leptin infusion. By contrast, the absence of a functional leptin receptor results in the upregulation of Npy but not Agrp mRNA.
Regulation of Glutamic Acid Decarboxylase 65 and 67 Gene Expression by Ovarian Steroids: Identification of Two Functionally Distinct Populations of GABA Neurones in the Preoptic Area
Authors: Curran‐Rauhut M. A. , Petersen S. L.
Published: March 2003

GABA neurones in the preoptic area (POA) are critical for oestradiol (E2)‐dependent surge release of luteinizing hormone (LH); however, it is not clear which population(s) of POA GABA neurones is involved. The goals of the present studies were: (i) to determine whether E2 regulates GABA neurones similarly in two subdivisions of the POA that play a role in LH surge release, the rostral POA region that contains the organum vasculosum of the lamina terminalis (rPOA/OVLT), and the region containing the anteroventral periventricular nucleus (AVPV) and medial preoptic nucleus (MPN) and (ii) to determine whether GABA neurones in either or both regions exhibit temporal changes consistent with a role in the regulation of LH surge release. To accomplish these goals, we measured glutamic acid decarboxylase (GAD) 65 and 67 mRNA levels at several time points in ovariectomized (OVX), E2‐treated OVX rats exhibiting LH surge release, and in E2‐treated OVX rats in which LH surge release was blocked by prior administration of progesterone (P4). Our findings demonstrate that, despite their close proximity, GABA neurones in the AVPV/MPN region are regulated differently from those in the rPOA/OVLT. Only neurones in the AVPV/MPN region show temporal changes in GAD 67 mRNA expression that appear to be linked to positive‐feedback effects of E2 on luteinizing hormone‐releasing hormone (LHRH) and LH release. Our findings also indicate that a morning rise and an afternoon fall in GAD 67 mRNA levels marks two E2‐dependent signals required for LHRH and LH surge release. Finally, our results suggest that there are distinct E2‐induced signals to the rPOA/OVLT and AVPV/MPN regions and that these signals differentially regulate GAD 65 and 67 gene expression.
Effects of Acute Treatment with 8‐OH‐DPAT and Fluoxetine on Aggressive Behaviour in Male Song Sparrows (Melospiza melodia morphna)
Authors: Sperry T. S. , Thompson C. K. , Wingfield J. C.
Published: March 2003

The role of serotonin in modulating male aggressive behaviour was investigated in male song sparrows, Melospiza melodia morphna, using two different serotonergic drugs, fluoxetine and 8‐OH‐DPAT. Fluoxetine is a selective serotonin reuptake inhibitor of the neuronal reuptake pump increasing synaptic concentrations of serotonin, and 8‐OH‐DPAT is a specific serotonin (5‐HT1A) receptor agonist. The serotonergic control of aggression in passerines has not been previously investigated. We examined these behaviours within a controlled setting using a laboratory simulated territorial intrusion, with a hierarchical scale to quantify male–male aggressive behaviour. Utilizing this scale, we quantified the extent of male aggressive behaviour in two experiments. In experiment 1, song sparrows were given 100 µl, s.c. injections of either fluoxetine (10 mg/kg) or 8‐OH‐DPAT (1 mg/kg). Experiment 2 was a dose–response study using three doses of 8‐OH‐DPAT (0.1, 1 and 10 mg/kg). In both studies, aggressive behaviour was measured 1 h after injection for 10 min in response to the presence of a novel male decoy combined with playback of conspecific song. Both drugs significantly reduced male aggressive behaviour, and 8‐OH‐DPAT did so in a dose‐dependent manner. The effect of the two drugs upon general activity was also measured using infra‐red perch hop detectors. Activity levels were not effected by either fluoxetine or 8‐OH‐DPAT at all of the respective doses, indicating that the reduction in aggressive behaviour was specific. These results demonstrate that, in a passerine species, the serotonergic system negatively regulates male–male aggressive behaviour. These results further demonstrate that aggression can be effectively studied in a laboratory setting and natural aggressive responses can be elicited using this method.
Effect of edentulousness on mandibular size and condyle‐fossa position
Authors: RauStia  , Pirttiniemi  , Salonen  , Pyhtinen
Published: March 2003

Modern imaging methods make possible the more precise examination of the complicated bony structure of the temporomandibular joint (TMJ) and the performance of cephalometric analysis. The aim of our study was to analyse the effect of edentulousness on the mandibular size and the condyle‐fossa position using roentgen‐cephalograms and axial computed tomography (CT) scans. The study group consisted of 20 edentulous patients (14 women, six men, mean age 60 years) whose mean period of edentulousness was 20 years (range 3–34 years). A CT examination of their TMJs was performed and roentgen‐cephalograms in 16 of this group were taken after prosthetic treatment. Sixteen dental students were chosen according to sex as controls. Earlier CT scans of 49 dentate subjects of both sexes were used as controls for the analysis of bicondylar asymmetry. The position of the glenoid fossa was more anterior in edentulous subjects than in dentate ones and its anterior position correlated significantly (P < 0·02) with the period of edentulousness, a finding which has not been confirmed before. It can be concluded that the fossa is a remodelling unit as a part of the functional entity when the function is altered dramatically as in the case of edentulous patients.
Effects of finishing/polishing time on surface characteristics of tooth‐coloured restoratives
Authors: Yap  , Sau  , Lye
Published: March 2003

This study compared the effects of immediate and delayed finishing/polishing procedures on the surface characteristics (surface roughness and hardness) of tooth‐coloured restoratives including a microfilled, a heavily filled and a polyacid‐modified composite resin and a resin‐modified glass–ionomer cement. Eighty‐four specimen discs were made for each material; the first 12 were used as controls and the remaining 72 specimens were randomly divided into two equal groups. The first group was finished/polished immediately after light polymerization and stored for 1 week in distilled water at 37 °C while the second group was finished/polished after 1 week storage in distilled water at 37 °C. Finishing and polishing was carried out using the following systems: Enhance® system, white stones with Vaseline® and Super‐snap® disks system. The finished/polished surfaces were subjected to profilometric evaluation and microhardness testing. The effects of delayed finishing/polishing procedures on surface roughness and hardness appear to be both material and technique dependent. Delayed finishing/polishing of polyacid‐modified composite resins and resin‐modified glass–ionomer cements generally resulted in a smoother surface. The surface roughness of composite resins after finishing/polishing procedures were generally not influenced by the finishing/polishing time. For all materials, delayed finishing/polishing with the various techniques generally resulted in a surface of similar hardness to or harder than that obtained with immediate finishing/polishing and the control group.
Evaluation of titanium in oral conditions and its electrochemical corrosion behaviour
Authors: Canay Sû. , Hersek N. , Çulha A. , Bilgiç S.
Published: March 2003

Due to its excellent biocompatibility and good mechanical properties, titanium has been used successfully in dentistry for many years. In this study, complete dentures with titanium palatal plates were applied to 10 patients who were in need of upper dentures. The clinical performance of cast titanium palatal plates was determined over a period of 6 months. No increase in accumulation of denture plaque nor mucosa irritation was observed. After the above period, the electrochemical corrosion behaviour of cast titanium and chromium–cobalt palatal plates were compared with the titanium plates that were not left in an oral environment after casting. For the electrochemical corrosion tests, a corrosion cell was designed and artificial saliva with lactic acid was used, with the temperature during the tests being about 37°C. The potential difference between the test sample and the saturated calomel electrode was measured, and after the determination of the rest potentials, the anodic potentiodynamic polarization curves were traced at a rate of 1 mV/s. From the standpoint of corrosion, the titanium plates used by the patients for a 6‐month period corroded more than the titanium not used by the patients. This may be due to the casting and processing conditions and the effect of the oral environment.
Effect of initiator concentration, exposure time and particle size of the filler upon the mechanical properties of a light‐curing radiopaque dental composite
Authors: Krishnan V. Kalliyana , Yamuna V.
Published: March 2003

Concentration of camphorquinone initiator, exposure time of the light source and particle size of a radiopaque glass filler have been varied for an indigenously developed light‐curing dental composite and the changes in the microhardness, compressive strength and diametral tensile strength studied. Higher initiator concentration and exposure times are found to improve the microhardness values while a concentration above 0·25% does not signify any drastic improvement in compressive and diametral strength. Changes in properties are found to be statistically significant at low initiator concentrations. A filler particle size around 1 μm is found to give better properties compared with larger sizes.
Evolution in time of the relationship between occlusion and tooth absence
Authors: Gonzalez‐gonzalez J. M. , Cabo‐valle M. , Diaz‐argüelles‐bru E.
Published: March 2003

The evolution in time of the relationship between occlusion tooth absence was studied in 204 people in Salamanca, in 1996. The data collected in an oral test (biting in maximal intercuspidation on articulating paper) were analysed using the method called expansion–contraction systems. The results show that the loss of occlusion through time is directly related to the absence of premolars and molars. Incisors and canines occlude more in elderly people. This supports the view of a polarization in the evolution of the occlusion towards canines and premolars whereas tooth absence is polarized towards molars.
Finite element analysis of non‐axial versus axial loading of oral implants in the mandible of the dog
Authors: Barbier L. , Sloten J. Vander , Krzesinski G. , Van Der Perre E. Schepers &G.
Published: March 2003

The influence of axial and non‐axial occlusal loads on the bone remodelling phenomena around oral implants in an animal experiment is simulated in a finite element analysis. The axial and non‐axial loading conditions were introduced by inserting a bilaterally supported fixed partial prosthesis and a cantilever fixed partial prosthesis on two IMZ® implants in the mandible of beagle dogs. Earlier quantitative and qualitative histological analyses revealed a statistically significant different remodelling response between both loading conditions. Two‐dimensional and three‐dimensional models are built to analyse and compare von Mises equivalent stress, maximum principal stress, maximum principal strain and strain energy density distributions, first around a free‐standing implant and subsequently around the implants of the two prosthesis designs under the respective resultant

in vivo

loads. Strong correlations between the calculated stress distributions in the surrounding bone tissue and the remodelling phenomena in the comparative animal model are observed. It is concluded that the highest bone remodelling events coincide with the regions of highest equivalent stress and that the major remodelling differences between axial and non‐axial loading are largely determined by the horizontal stress component of the engendered stresses.
Effect of fluorosis on etching of human enamel
Authors: Al‐Sugair M. H. , Akpata E. S.
Published: March 2003

To investigate the effect of fluorosis on the pattern and depth of etch of human enamel, 420 enamel specimens classified according to the Thylstrup and Fejerskov index (TFI) were etched with 37% phosphoric acid for varying times. The mean depths of etch for mildly fluorosed enamel (TFI=1–3) were generally dependent on etching time (r=0·55–0·76), and were not significantly different from the depth obtained for non‐fluorosed (TFI=0) specimens. The enamel specimens with more severe fluorosis (TF=4) required longer etching time which showed little correlation with the mean depth of etch (r=0·15–0·16). Furthermore, the etched specimens showed typical enamel etching patterns, independent of the severity of fluorosis. When the specimens with TFI=4 were etched for 45 s, the subsurface organic network was evident, but this disappeared and typical etching patterns could be seen again when etching time was increased to 75–90 s. It is therefore concluded that the diagnosis of the severity of fluorosis must first be made whenever etching of fluorosed enamel is contemplated.
A multiparametric analysis of occlusal and periodontal jaw reflex characteristics in adult skeletal mandibular protrusion before and after orthognathic surgery
Authors: Suda Satoru , Machida Naoki , Momose Manabu , Yamaki Masaki , Seki Yasuhiro , Yoshie Hiromasa , Hanada Kooji , Hara Kohji
Published: March 2003

Periodontal jaw reflex, duration of percussion sounds, tooth mobility, and time‐moment analysis of occlusal contacts by the T‐scan system were recorded in seven pre‐orthognathic surgery patients and six post‐orthognathic surgery patients over a 2‐year period. The results showed that: (i) reflex response to the pressure applied to the upper right central incisor in the lingolabial direction varied, depending on the background jaw‐clenching force (BCF) of the same‐sided first molar. The BCF level required to elicit excitatory reflexes was only 0 kgf, and inhibitory reflexes were clearly elicited with a BCF of 1 kgf and beyond before orthognathic surgery. After orthognathic surgery BCF levels required to elicit excitatory reflexes were 0–4 kgf, and inhibitory reflexes were elicited with a BCF of 6 kgf and above; (ii) duration of percussion sounds determined via an occlusal sound analyser decreased in both the upper right central incisor and upper right first molar while tooth mobility measured by ‘Periotest®’ increased in the upper right central incisor, but did not change in the same‐sided first molar after orthognathic surgery; (iii) the time moments of occlusal contacts were symmetrical toward the midsagittal axis of the occlusal plane after orthognathic surgery. The centre of the anterioposterior occlusal contacts did not differ between pre‐ and post‐orthognathic surgery groups.
In vitro permeability and scanning electron microscopy study of acid‐etched and ground enamel surfaces protected with dental adhesive coating
Authors: Kuhar M. , Cevc P. , Schara M. , Funduk N.
Published: March 2003

Clinical procedures, such as acid etching and reshaping of the teeth supporting removable partial dentures by grinding off some enamel surface, increase the permeability of dental enamel. Teeth take several months in vivo to partially recover from such damage. In the meantime, the tooth is more susceptible to carious decay. To prevent this the ground or etched enamel should be effectively protected. Using electron paramagnetic resonance (EPR) and a two‐chamber diffusion cell the authors studied the influence of adhesive resin applied to the ground and acid‐etched enamel surfaces on the diffusion of spin label TMAPO (2,2,6‐6 tetramethyl‐4‐acetamido‐piperidine‐1‐oxyl) molecules through the enamel. The enamel permeability was measured in samples exposed to 1‐min etching with 37% phosphoric acid, in samples etched for 5 min, and in samples ground with a diamond bur. Next, all the treated enamel surfaces were coated with Scotchbond Multi‐Purpose Plus® dental adhesive system and the permeability measurements repeated. Scanning electron microscopy (SEM) was used to study the porosity of enamel surfaces. The adhesive resin film covering the etched or ground enamel surfaces was found to decrease significantly the diffusion through dental enamel. This finding confirms the clinical value of dental adhesives used to protect ground or accidentally acid‐etched enamel surfaces. SEM analysis showed that adhesive resin covers the porous surface of the acid‐etched and ground enamel tightly.
The thermal insulating effects of five dental gloves
Authors: Chadwick R. G.
Published: March 2003

On occasions within the case reports of the various medico‐legal defence organizations mention is made of burns to the oral soft tissues arising from contact with a heated instrument. Good cross infection control dictates that the dentist should be gloved whilst treating patients. No study has to date examined the thermal insulating effect of wearing dental procedure gloves although double gloving is known to blunt temperature perception. It was the purpose of this work to compare the degree of thermal insulation afforded by five makes of gloves (Biogel‐D, Featherlite, Healthline, Microtouch and Tru‐Touch). Measurement of temperature rises at 15, 30 and 60 s were made when a copper cylinder, at ambient room temperature, containing an iron/constantan thermocouple was placed upon a 2·35 kg aluminium block maintained at 50 °C by a thermostatically controlled electrical heating element. This measurement was initially performed, on 10 separate occasions, with the aluminium block and copper cylinder in direct contact (Control). This arrangement was then modified to investigate the effects of the various gloves by placing a circular mat of each glove material, harvested from the palm of each glove, between the block and cylinder. For each glove, 10 sets of observations were made using a different circular mat of glove material whose thickness had been previously determined. An analysis of variance identified highly significant (P<0·001) differences between the temperature rise of the control and experimental groups. The degree of thermal insulation afforded by each glove type appeared related to the glove thickness. This was confirmed by regression analysis but, although correlation coefficients of at least 0·91 were recorded, no single relationship best related these two quantities. Glove thermal insulating properties should be considered when selecting gloves for use in the surgery.
The function of tensor veli palatini muscles in patients with aural symptoms and temporomandibular disorder. An EMG study
Authors: Penkner K. , Köle W. , Kainz J. , Schied G. , Lorenzoni M.
Published: March 2003

This preliminary study investigated Myrhaug's neuromuscular hypothesis by means of audiological and electromyographic assessment. After a clinical examination of the TMJ system, the activity of the tensor veli palatini muscles in the state of rest and during swallowing was investigated in 16 patients with the help of an EMG recording, and the tube‐opening function was evaluated endoscopically. Results showed that 6·25% of the patients suffered from mild joint‐dysfunction (group I), 81·25% from a moderate dysfunction (group II), and 12·5% from severe dysfunction (group III). Although five patients suffered from tinnitus and 11 from fullness in the ear, both the audio‐ and tympanogram performed on 15 patients displayed normal recordings. Only one patient suffered from moderate sensorineural hearing loss. In the EMG recording, 11 of the 16 subjects displayed normal EMG patterns in state of rest and during swallowing contraction. In two cases, abnormal EMG recordings were obtained due to incorrect insertion of the EMG needle. The study's results indicate that spasm in the masticatory muscles of TMJ patients neither seems to cause reflex spasm of the tensor palatini muscles nor to effect significant alterations in Eustachian tube function.
Vibrating‐traction method for mechanical joint distraction
Authors: Minagi S. , Sakiya M. , Sato T. , Matsunaga T. , Natsuaki N.
Published: March 2003

Mechanical static traction has been adopted as one of the treatment procedures for joint diseases and fractures. The effect of mechanical vibration on the mechanical traction of the temporomandibular joint was studied in six human subjects. A mechanical traction force of 2000 gf was applied as a dynamic traction force with mechanical vibration or as a static traction force. The dynamic traction force with vibration was applied for 5 min to the right temporomandibular joint using a vibrating‐traction apparatus which generated mechanical vibrations of 1000, 3000 or 4000 Hz. Application of a static traction force for 5 min was used as a control condition. Vertical condylar displacement was mathematically evaluated from the deviation of the mandible using Eddy current displacement sensors which were attached to the maxillary dental arch. Among the three vibration frequencies, 3000 Hz resulted in the maximum vertical condylar displacement for all six subjects, showing the mean condylar displacement of 668±242 μm. In contrast, vibrations of 1000 and 4000 Hz showed a smaller traction effect. Application of the static traction force for 5 min resulted in a mean vertical condylar displacement of 5·7±4·9 μm, showing almost no traction effect to the joint. From the results of this study, it was revealed that vibrating traction could distract a joint more effectively than could static traction and that the traction force necessary for effective vibrating traction was less than that for static traction.
Masticatory movement in two cases with unusual alignment of the maxillary canine
Authors: Murakami T. , Harada T. , Abe K. , Tanaka T.
Published: March 2003

Masticatory function was analysed before and after orthodontic treatment in two cases where tooth alignment remained unusual after treatment. The Sirognathograph Analyzing System® was used to analyse the masticatory function. In both cases, the right maxillary first premolar was located where the maxillary canine is normally positioned. The results of orthodontic treatment were satisfactory both morphologically and aesthetically, and masticatory function was greatly improved. However, some problems remained in the mandibular movement due to the abnormal contact between the mandibular teeth and the maxillary first premolar. These findings support the need for examination of masticatory function when treating patients with an unusual tooth alignment even if the results of orthodontic treatment are both morphologically and aesthetically successful.
EMG–force relationships are influenced by experimental jaw‐muscle pain
Authors: Wang K. , Arima T. , Arendt‐Nielsen L. , Svensson P.
Published: March 2003

The bite force at different levels and the corresponding electromyographic (EMG) activity of the masseter and anterior temporalis muscles were recorded in 12 healthy subjects in order to evaluate the modulation of EMG–force curves by a standardized painful stimulus. Hypertonic saline (5%) was infused into the right masseter muscle for up to 15 min to induce pain. The pain intensity was scored continuously by the subjects on a 10‐cm visual analogue scale (VAS). Subjects were asked to bite on a force transducer at the maximum voluntary bite force (MVBF). They were then asked to bite at submaximum levels of 12, 25, 37, 50, 67, 75 and 87% of MVBF. The biting was performed in three different positions (right first molar, left first molar and incisor) before, during and after infusion. Hypertonic saline caused moderate pain during infusion (mean VAS±s.e.m.=6·5±0·5 cm). Both the MVBF and the maximum EMG activity in the right masseter and the left anterior temporalis muscles were significantly decreased during muscle pain when the subjects bit on the painful side. The EMG–force curves could be fit by linear relationships. The slope of the curve became less steep in the right masseter muscle during and after painful biting in every position. The results suggest that tonic saline‐induced jaw‐muscle pain is able to modulate the motor unit recruitment pattern of the jaw‐closing muscles on the painful side. The main effect of pain in this experiment was an inhibition of static EMG activity.
The effects of chewing rates on mandibular kinematics
Authors: Throckmorton G. S. , Buschang B. H. , Hayasaki H. , Phelan T.
Published: March 2003

The purpose of this study is to provide basic understanding of how the speed of chewing affects masticatory jaw kinematics. Twenty‐six healthy subjects (23·6 ± 2·5 years of age) chewed a standardized bolus of gum at fast (100 cycles s−1), habitual and slow (50 cycles s−1) rates. The rates were controlled with a metronome and the order of rates was randomized for each subject. An optoelectrical system independently recorded head and jaw movement. Special computer programs identified representative cycles for each subject and computed various aspects of jaw movement. Multilevel statistical procedures were used to compare cycle variables among the three rates, estimate variability and model jaw movements. Maximum ranges of anteroposterior (AP), vertical and lateral jaw excursions were significantly less for the fast than the habitual or slow rates. While the shape of 3‐D pathway was similar for the three rates, the perimeter of the pathway was significantly shorter for fast chewing cycles. Maximum AP, vertical, lateral and total 3‐D jaw velocities were significantly different among the three rates. Between cycle variation in cycle duration and jaw excursion were least during fast chewing and the greatest during slow chewing; variability in maximum velocity was similar for the three rates.
Degree of conversion and temperature rise during polymerization of composite resin samples with blue diodes
Authors: Knežević A. , Tarle Z. , Meniga A. , Šutalo J. , Pichler G. , Ristić M.
Published: March 2003

To ensure an adequate clinical composite filling light source for photopolymerization is of great importance. In everyday clinical conditions commonly used unit for polymerization of composite material is halogen curing unit. The development of new blue superbright light emitting diodes (LED) of 470 nm wavelengths comes as an alternative to standard halogen curing unit of 450–470 nm wavelengths. The purpose of this study was to compare the degree of conversion (DC) and temperature rise of four hybrid composite materials: Tetric Ceram, Pertac II, Valux Plus and Degufill Mineral during 40 s illulmination with standard halogen curing unit Heliolux GTE of 600 mW cm−2 intensity, Elipar Highlight soft‐start curing unit of 100 mW cm−2 (10 s) and 700 mW cm−2 (30 s) intensity and 16 blue superbright LED of minimal intensity of 12 mW cm−2 on the surface and 1 mm depth. The results revealed only a little bit higher DC values in case of polymerization with even 66 times stronger halogen curing units which showed twice higher temperature than blue diodes. Temperature and DC obtained are higher on the surface than on 1 mm depth regardless on the light source used.
An investigation into the transverse and impact strength of `high strength' denture base acrylic resins
Authors: Jagger D. C. , Jagger R. G. , Allen S. M. , Harrison A.
Published: March 2003

A range of materials, often marketed as high strength resins is available. These materials are often expensive options to conventional heat‐cured acrylic resin. The aim of this study was to investigate transverse and impact strength of five `high strength' acrylic resin denture base materials. A conventional heat‐cured acrylic resin was used as a control. Specimens were prepared as specified in the International Standard Organization (ISO 1567: 1988) and British standards for the Testing of Denture Base Resins (BS 2487: 1989) and the British Standard Specification for Orthodontic resins (BS 6747: 1987) for transverse bend and impact testing. The impact strength was measured using a Zwick pendulum impact tester and the transverse bend strength measured using a Lloyds Instruments testing machine. The results showed that Metrocryl Hi, Luctitone 199 and N.D.S. Hi all had an impact strength which was significantly higher than the control. For the modulus of rupture, there was a significant difference between Sledgehammer and the other groups. There was no significant difference between the other groups and the control. For the modulus of elasticity, Sledgehammer produced the highest value followed by the control. The remaining four materials had a modulus of elasticity less than the control.
Longevity of fixed metal ceramic bridge prostheses: a clinical follow‐up study
Authors: Näpänkangas R. , Salonen‐Kemppi M. A. M. , Raustia A. M.
Published: March 2003

The aim of this study was to evaluate the factors that influence the longevity of fixed metal ceramic bridge prostheses, including the length of the bridge as well as the basic circumstances of the mouth. A total of 132 patients attended the clinical examination. There were 84 women (64%) and 48 men (36%). Patients had altogether 195 bridges, which included 157 short bridges (3–5 units) and 47 long bridges (6 and more units). The overall clinical examination was performed including the intra‐oral radiographs. The salivary findings of the patient at baseline [flow rate of stimulated saliva, scores of mutans streptococci (SM) and lactobacilli (LB)] were registered from the patient files. In addition, the patient files were examined to receive further information concerning the complications treated in our clinic. On the basis of severe and extensive complications, the overall survival after 10 years was 84%. Long bridges had lower survival than the shorter ones (P=0·04). A low secretion of saliva recorded before the prosthetic treatment decreased the survival of the bridges (P=0·12) and the survival of the bridges was likewise reduced by high scores of LB and SM (P=0·07). Age of the patient did not influence the survival. It was shown here that long bridges (5 and more units) have a lower survival than the short bridges. It can be concluded, however, that the low secretion of saliva and the high scores of lactobacilli and SM have a remarkable influence on complications and these facts should therefore be taken into careful consideration in choosing the patients for the prosthetic treatment with fixed prosthodontics.
Effectiveness of exercise therapy in patients with myofascial pain dysfunction syndrome
Authors: Nicolakis P. , Erdogmus B. , Kopf A. , Nicolakis M. , Piehslinger E. , Fialka‐Moser V.
Published: March 2003

Twenty consecutive patients suffering from myofascial pain dysfunction (MPD) were assigned to a waiting‐list, serving as a no‐treatment control period. Inclusion criteria were: (i) pain in the temporomandibular region for at least 3 months, (ii) no evidence of internal derangement or osteoarthritis and (iii) symptoms of postural dysfunction. Treatment consisted of active and passive jaw movement exercises, correction of body posture and relaxation techniques. The following main outcome measures were evaluated: (i) pain at rest, (ii) pain at stress, (iii) impairment, (iv) mouth opening at base‐line, before and after treatment and at 6‐month follow‐up. All patients completed the study and no adverse effects occurred. During control period no significant changes occurred. After treatment six patients had no pain at all (chi‐square: P < 0·01) and seven patients experienced no impairment (chi‐square: P < 0·005). Pain at stress, impairment and incisal edge clearance improved significantly (Wilcoxon test P < 0·001). This result did not change until follow up, except pain at stress, which further improved significantly (Wilcoxon test P < 0·03). At follow up 16 patients experienced no pain at all, 13 patients were not impaired and only three patients had a restricted mouth opening, in contrast to 12 before treatment (chi‐square test P < 0·001). Conclusion:  Exercise therapy seems to be useful in the treatment of MPD Syndrome.
Finite element stress analysis of the effect of short implant usage in place of cantilever extensions in mandibular posterior edentulism
Authors: Akça K. , İpli̇kçi̇oğlu H.
Published: March 2003

Although the destructive effect of cantilevered implant supported fixed partial prosthesis is well known, in some cases usage of cantilever extension seems to be inevitable for many clinicians. The purpose of this study was to evaluate the effect of additional placement of a shorter implant in place of a cantilever extension on stress distribution compared with cantilevered fixed prosthesis in mandibular posterior edentulism. A mandibular Kennedy II finite element model was constructed. Six different implant supported fixed partial prosthesis were designed according to two main configurations; anterior and posterior cantilever extensions compared with the placement of additional shorter implant configurations. An oblique occlusal load of 400 N was applied. Tensile and compressive stress values in the cortical bone surrounding the cervical regions of implants and Von Misses stress values in the implants were evaluated. Significant lower stress values were recorded at the shorter implant placement configurations compared with the cantilevered prosthesis. Posterior cantilever extension performed higher stress values than the anterior counterpart. In clinical applications where cantilevered fixed partial prosthesis seems to be inevitable because of anatomical restrictions and/or complications such as loss of implant, an additional placement of a shorter implant should be considered.
Radiological examination of dental castings – a review of the method and comparisons of the equipment
Authors: Eisenburger Michael , Addy Martin
Published: March 2003

summary The mechanical stability of crowns or bridges as well as frameworks for removable partial dentures depends on factors like thickness and metal structure. The biological compatibility can be influenced by porosities and soldered joints.

Radiological testing is a non‐destructive method to check defects in dental castings. As dental precious metal alloys have high X‐ray absorption, testing of high gold alloys should be performed with a suitable X‐ray machine at a tube voltage of 120 kV since the X‐ray penetration of dental X‐ray units using a tube voltage of 70 to 80 kV is not high enough for these alloys. As the absorption of Co–Cr alloys and of titanium is much lower, these materials can be tested with a dental X‐ray apparatus.

The radiographs show location and size of metal defects. They enable an examination of metal thickness and content of porosities. Metal defects reducing the biological compatibility or cast stability can be detected prior to clinical fitting.
Analysis of the area and length of masticatory cycles in male and female subjects
Authors: Barciela Castro N. , Fernandez Varela J. M. , Martin Biedma B. , Rilo Pousa B. , Suarez Quintanilla J. , Gonzalez Bahillo J. , Varela Patiño P.
Published: March 2003

summary  It is difficult to determine the existence of a normal or physiological masticatory cycle, because there exists great individual diversity. This study presents some data about two parameters of masticatory cycles according to the frontal plane, i.e. the area and length of right‐sided and left‐sided cycles in a group of 30 young people, 18 women and 12 men. For our study the Myotronics K6‐1 kinesiograph was used. It registers the magnetic field and allows us to obtain graphic recordings of the jaw movement in the three space planes. Other authors have analysed these parameters, but none of those reviewed provides information about the distribution to each side or according to the gender of sampling subjects selected for the analysis. We have tried to describe the normal morphology of the masticatory cycles and, also, establish a reference so as to provide help in the diagnosis of the functional pathology of the masticatory system.
Is there a relationship between head posture and craniomandibular pain?
Authors: Visscher C. M. , De Boer W. , Lobbezoo F. , Habets L. L. M. H. , Naeije M.
Published: March 2003

SUMMARY  An often‐suggested factor in the aetiology of craniomandibular disorders (CMD) is an anteroposition of the head. However, the results of clinical studies to the relationship between CMD and head posture are contradictory. Therefore, the first aim of this study was to determine differences in head posture between well‐defined CMD pain patients with or without a painful cervical spine disorder and healthy controls. The second aim was to determine differences in head posture between myogenous and arthrogenous CMD pain patients and controls. Two hundred and fifty persons entered the study. From each person, a standardized oral history was taken and blind physical examinations of the masticatory system and of the neck were performed. The participants were only included into one of the subgroups when the presence or absence of their symptoms was confirmed by the results of the physical examination. Head posture was quantified using lateral photographs and a lateral radiograph of the head and the cervical spine. After correction for age and gender effects, no difference in head posture was found between any of the patient and non‐patient groups (P > 0·27). Therefore, this study does not support the suggestion that painful craniomandibular disorders, with or without a painful cervical spine disorder, are related to head posture.
Automated analysis for portable EMG recording of nocturnal masseter activity in bruxers
Authors: GALLO L. M. , ROMPRÉ P. , LAVIGNE G. , PALLA S.
Published: March 2003

Facial pain of patients with craniomandibular disorders might be caused by muscle overload. In a former study (Gallo et al., 1999) we collected data on masseter EMG of healthy subjects during sleep by means of portable recorders (integration time of 500 ms). The automated analysis of the tracings yielded the normal range of activity in the natural environment. For this study, we focused on the analysis of the distribution of masseter activity in bruxers by means of the same automated system used for asymptomatic subjects.

For this purpose, data from single masseter channels of polysomnographic recordings of 10 bruxers and 10 controls were reformatted as if they had been recorded by means of the portable devices. The signals were analysed for number, amplitude and duration of contraction episodes (signal portions above a threshold which could contain subthreshold portions shorter than the standby time of 5 s). The signal amplitude was expressed in percentage of the amplitude at maximum voluntary contraction (%MVC).

In the bruxers, 166·8 ± 48·5 contraction episodes per night, i.e. 20·4 ± 5·7 h

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, with a net duration of 8·4 ± 2·4 s and an integral of the amplitude over time of 191·6 ± 74·0 %MVCs were found (controls: 96·5 ± 39, 12·9 ± 3·5, 4·7 ± 1·2 s and 99·1 ± 28·0 %MVCs, respectively). For these parameters there was a statistically significant difference between the two groups (t‐test, P < 0·01). The distribution of all contraction episodes of all bruxers according to net duration and mean amplitude was shifted towards shorter episodes with a massive presence of episodes between 60 and 70% MVC, much higher than in controls.