bluuebunny/crossref_metadata_2025_split huggingface dataset:
The masseteric reflex evoked by tooth and denture tapping
Authors: BRODIN P. , FLØYSTRAND F. , ØRSTAVIK J. 
Published: June 2007

SummaryThe characteristics of the masseter reflex evoked by tapping a maxillary incisor were compared with the reflex pattern evoked by tapping a corresponding denture tooth after insertion of an immediate denture. Up to three inhibitory phases (I‐1, I‐2 and I‐3), followed by excitation, were found on an averaged EMG. The tapping force threshold for the early inhibitory phase was lower than for the late phases. The pattern of the reflex was generally the same before and after insertion of the denture, but the threshold values increased. After insertion of the denture, the threshold for I‐1 increased from 1±0.3N to 2.2±0.4N, the threshold for I‐2 increased from 2.4±0.8N to 3.8±0.9N, and the threshold for I‐3 increased from 5.1±0.6N to 8.3±0.9N. The latency period for I‐1 also increased from 12.3±0.5 ms to 13.1±0.3 ms after insertion of the denture. After relining, the threshold for evoking I‐1 decreased from 2.7±1.2N to 1.2±0.6N. It was assumed that the mechanoreceptors situated in the mucosa under the denture base could take over the functional role of the periodontal mechanoreceptors for evoking the masseter reflex during tapping, and that these afferents probably had connections to the same interneurones.
Effect of occlusal bite‐raising splint on electromyogram, motor unit histochemistry and myoneuronal dimensions in rats
Authors: YAFFE A. , TAL M. , EHRLICH J. 
Published: June 2007

SummaryComposite resin bite‐raising splints were fabricated on both sides of the upper jaw in rats. EMG activity of the deep masseter muscle was monitored continuously for 24 h before and up to 4 weeks after treatment. Together with the EMG activity, measurements of the neuromuscular junction area and muscle fibre histochemistry were made. EMG activity showed great variability immediately after splint fabrication. Some of the animals showed increased EMG activity, while others exhibited less activity 48 h after splint application. Overall, the fluctuation lasted for about 4 days, and after approximately 7 days all the animals exhibited decreased EMG activity, followed by a gradual increase in activity towards baseline levels. The neuromuscular junction territory increased significantly 5–10 days after splint application. Histochemical characterization of the deep masseter muscle revealed that it contained the three main types of muscle fibre: slow oxidative (SO), fast‐oxidative‐glycolytic (FOG) and fast glycolytic (FG). The frequency distribution of fibre types did not change after bite‐raising splint treatment. These findings indicated that splint treatment in rats is effective in reducing EMG activity, while the muscle type characteristics remain stable. The effect of lower activity on the motor end‐plates suggested that the neuromuscular junctions are quite sensitive to functional changes.
The relationship between failure and design in conventional bridgework from general dental practice
Authors: FOSTER L.V. 
Published: June 2007

SummaryA total of 142 failed bridges constructed in general dental practice were assessed for design factors that might relate to failure. The overall mean age of the bridges at failure was 6.2 years; anterior and complex bridgework had a mean age of about 5 years, compared with 7.5 years for posterior bridges. The lifespan of the bridgework was significantly correlated with the number of retainers but not with the number of units. Bridges with one or two retainers had an average lifespan of just over 7 years, whilst those with three or more retainers had been in service for, on average, only 4 years. The practical difficulties of constructing multi‐abutment bridgework could account for this difference. One hundred and ninety‐one of the 346 retainers were porcelain bonded to semi non‐precious metal crowns, and had a mean lifespan of 3.7 years, whilst those that were gold based lasted at least twice as long. Post crowns as retainers survived on average for 6.2 years.
Orthognathic diagnosis and treatment planning: a cephalometric approach
Authors: CHACONAS S.J. , FRAGISKOS F.D. 
Published: June 2007

SummaryCephalometric analyses have long been important diagnostic tools for the orthodontic specialist. Such analyses, as they pertain to adult skeletal problems and their consequent therapy, should also be a valuable adjunct for various dental specialties, e.g. the oral surgical clinician. However, because of the complexity of most analyses, it is difficult to glean the important values needed for most orthognathic cases. In this article an analysis is presented to aid the clinician in surgical diagnosis and treatment planning.
Activity index and isometric contraction velocity of human jaw muscles
Authors: CHRISTENSEN L. V. , KUNDINGER K.K. 
Published: June 2007

SummaryTo determine the relative contribution of the masseter and anterior temporalis muscles to global isometric bite force, activity indices were constructed on the basis of the peak mean voltage (μV) and the integrated voltage (μV.s) of bipolar surface electromyograms obtained during brief maximum voluntary teeth clenching (MVC). The index that was based on integrated myoelectrical activity showed that the masseter muscle contributed the major part of the isometric MVC force. The index that was based on instantaneous peak myoelectrical activity also showed that activity in the masseter muscle predominated over that in the anterior temporalis muscle. In addition, the latter index showed a negative linear association with the initial (0–50% MVC) isometric contraction velocities of the masseter and anterior temporalis muscles. Both indices appear to be promising clinical diagnostic tools.
Use of shell crowns in Hong Kong dental hospital attenders
Authors: CORBET E.F. , HOLMGREN C.J. , PANG S.K. 
Published: June 2007

SummaryIn 1984 an oral health survey of Hong Kong adults aged 35–44 years revealed that 15% of subjects presented with metal shell crown restorations, often as components of fixed‐bridge reconstructions. The aim of this study was to describe the patterns and means of use of shell crowns, and to describe the patterns of tooth loss in patients who presented with such restorations, attending for treatment at the dental teaching hospital in Hong Kong over a 2‐year period. A total of 1563 such patients attended. The records, which included radiographs, of 165 of these patients aged 35 years and above, obtained by means of a systematic sampling frame, were studied by one trained examiner. On initial presentation each patient was found to have a mean of 4.0 shell crowns, 77% of these being components of bridge restorations. The bridges involved a mean of only 3.9 units (retainers and pontics). The tooth type most commonly replaced by a bridge of this type was the first molar. It was concluded that most shell crowns used in this patient group are abutment retainers for predominantly short‐span bridge restorations.
Microleakage studies comparing a one‐visit indirect composite inlay system and a direct composite restorative technique
Authors: CASSIN A.M. , PEARSON G.J. 
Published: June 2007

SummaryProblems related to leakage have been observed with direct‐filled composite restorations. The development of indirect system of fabrication followed by cementation should theoretically reduce this phenomenon. The present study compares the leakage around directly placed composites with composite inlays prepared by a surgery‐based system. The results indicate that the amount of leakage is reduced with the inlay system, but that it is not eliminated.
Non‐cast titanium restorations in fixed prosthodontics
Authors: BOENING K.W. , WALTER M.H. , REPPEL P.‐D. 
Published: June 2007

SummaryThe problems encountered in casting titanium in dentistry have not been completely resolved. The Procera system forms crowns by means of a combination of spark‐erosion and milling. The accuracy of fit was examined before and after ceramic veneering both in vitro and in vivo. Before veneering, on conical surfaces space widths were approximately 53 μm in vitro and 69 μm in vivo. At shoulders and occlusal surfaces, spaces of about 430 μm were measured in vitro and of about 500 μm were measured in vivo. After ceramic veneering, slight increases in space widths could be observed. The metal‐ceramic compound was tested by the 3‐point bending test (DIN) and the bending test (ISO). The DIN test was satisfactory, but not the ISO test. It is concluded that titanium crowns processed by the Procera System are suitable for clinical usage, if the space widths at shoulders and the occlusal surface and the special requirements of tooth preparation are taken into account.
Maximum jaw opening capacity in adolescents in relation to general joint mobility
Authors: WESTLING L. , HELKIMO E. 
Published: June 2007

SummaryMandibular jaw opening was related with general joint mobility in a non‐patient adolescent group. The angular rotation of the mandible at maximum jaw opening was slightly larger in females than in males and significantly larger in hypermobile individuals. No significant relationship between linear measuring of maximal mandibular opening capacity and peripheral joint mobility was found either at active (AROM) or at passive range of mandibular opening (PROM). PROM was strongly correlated to the mandibular length. Clinical signs in the great jaw closer muscles could not be associated to decreased AROM. The mean value of the difference between PROM‐AROM (DPA) was 1.2mm. Frequent clenching and/or grinding was correlated to increased DPA only in hypermobile adolescents (r=0.49***). Those with DPA exceeding 5 mm had all reciprocal clicking.
Electromyographic parameters related to clenching level and jaw‐jerk reflex in patients with a simple type of myogenous cranio‐mandibular disorder
Authors: BUCHNER R. , VAN DER GLAS H.W. , BROUWERS J.E.I.G. , BOSMAN F. 
Published: June 2007

SummaryA discriminant analysis has been applied on several electromyographic (EMG) parameters of the masseter and the anterior temporal muscles, related to clenching and the jaw‐jerk reflex, to characterize jaw muscle function of patients with craniomandibular disorder (CMD) with respect to controls. The subject samples, matched for age, consisted of 20 females with myogenous CMD, and 20 symptom‐free females. The jaw‐jerk reflex was elicited by a downward‐directed mandibular load, transmitted by a bite‐fork causing a similar occlusion and bite‐rise as a splint. The patients differed mainly from the controls by smaller maximum EMG activity in both muscle groups (P<0.05 with the bite‐fork inserted). This finding was related to a smaller muscle strength as the EMG level did not improve with pain‐free jaw muscles after therapy using a relaxation splint. Discriminating factors of secondary importance were an enhanced bilateral asymmetry in the muscle activity of the patients, and in the reflex amplitude normalized for background EMG activity. In all subject samples, the activity of the anterior temporal muscles decreased with respect to the masseter muscles when the bite‐fork was inserted (P<0.05–0.001). The therapeutic effect of a relaxation splint may, in part, be related to a relief of the temporal muscles.
Shrinkage of tissue conditioners with time — effect of the particle size in powder and the EtOH content in liquid
Authors: MURAKAMI S. , MURATA H. , SADAMORI S. , SHIGETO N. , HAMADA T. 
Published: June 2007

SummaryThe dimensional change of tissue conditioners with time was measured until 4 weeks after mixing. Shrinkage of the materials was evaluated in relation to particle size in powder and the EtOH content in liquid. The dissolution of EtOH and plasticizer were also measured to investigate the relation to dimensional change. Shrinkage with time was recorded. The smaller the particle size in powder and the more EtOH in liquid, the greater the shrinkage rate. The smaller the particle size in the powder and the more EtOH contained in the liquid, the greater the dissolution of EtOH. The dissolution of BPBG was below 1/100 comparing that of EtOH and no difference was recognized by particle size and EtOH content.On the basis of these results it is suggested that the dissolution of EtOH is related to shrinkage of tissue conditioners with time and that the component particle size in the powder and EtOH content in the liquid have a significant influence on dissolution of EtOH associated with shrinkage.
Relationship between autoregressive model coefficients of EMG and its potentials of jaw closing muscles at rest position and clenching
Authors: SHI C.‐S. , HUA Z. Y. 
Published: June 2007

SummaryAt rest position and varied clenching levels at intercuspal position, autoregressive (AR) models of myoelectrical activities of both masseter and anterior temporal muscles of 11 healthy subjects with intact natural dentitions were established. The relationship between the AR model coefficients of surface EMGs and their potentials was analyzed by multiple linear regression. It was found that the fourth order coefficient of AR had the greatest effect on the EMG potential levels and their relationship was positive in all recorded muscles. The results indicate the AR coefficients may become a characteristic parameter to describe myoelectrical activity of jaw closing muscles.
The ‘temporomandibular pain dysfunction syndrome’ personality: fact or fiction?*
Authors: MARBACH J.J. 
Published: June 2007

SummaryIt is widely accepted that abnormal personality traits are important factors in the aetiology and maintenance of the temporomandibular pain and dysfunction syndrome (TMPDS). However, the foundation upon which this paradigm rests is largely based on clinical lore rather than evidence. The continued belief in the stress theory has onerous implications. First of all, clinicians could be lulled into a false sense of security about the efficacy of traditionally sanctioned treatments. Second, and potentially more important is the chilling effect on research that results from the premature and unsupported conclusions voiced by many, that certain issues regarding the diagnosis and treatment of TMPDS are solved. Such conclusions will lead not only to problems of patient care but may forge an unstable foundation for future research. Three theories are examined for convergent evidence in support of the putative relationship between personality and TMPDS. They are the 1) psychosomatic 2) coping and 3) psychophysiological theories. Currently evidence lacks for all three theories although there is partial support for the latter. It has not been demonstrated that TMPDS cases are characterized by a specific premorbid personality.
Level of accuracy and degree of precision in attempting to maintain steady levels of biting force
Authors: WILLIAMS W.N. , COFFEY J. , TURNER G.E. , CRARY M.E. , CAPEN R. , WHARTON P.W. 
Published: June 2007

SummaryThe primary purpose of this study was to assess the level of accuracy (bias) and degree of precision for a group of 24 normal subjects attempting to maintain a contsant biting force at levels of 100 gm. 500 gm, 100 gm and 2000 gm for a period of 10s each. Accuracy is defined as the difference between subjects actual level of biting force and the target value they were trying to achieve. Precision is the level or range of variability demonstrated by the subjects while attempting to bite with a constant level of force. Subjects performance relative to accuracy and precision was also compared when using the central incisors vs. the first permanent molars. Assessment of bite force was measured using a specially designed strain gauge scale which permitted subjects to visually monitor when their biting force equalled a preset resistance. Each subject was instructed to bite on the end of a plastic sheathed steel beam with enough foree to activate the indicator needle on the voltage meter to its central position and to try to maintain a constant level of biting foree (by attempting to keep the indicator needle steady in its central position). No significant (P > 0.05) differences were found in mean accuracy in bite force for gendeer or specific teeth used in the biting task. However, a significant difference (P < 0.0001) in mean accuracy in bite force was found to exist between the target elvels. At the lowest standard force (100 gm) there was a mean group bias of +17 gm while at the highest standard (2000 gm) the mean group bias was −103 gm. Analysis of subjects precision in biting force revelaed significant differences in performance relative to gender (P <0.0001), teeth (P > 0.01) and target levels (P < 0.0001).
Swallowing activity of lip muscles in patients with a complete upper and a partial lower denture
Authors: TALLGREN A. , TRYDE G. 
Published: June 2007

Summary In 30 partially edentulous subjects provided with an immediate complete upper and a partial lower free‐end denture the lip activity in swallowing was studied before and after denture treatment and during a 2‐year period of denture wearing. Electromyographic recordings of the right side upper and lower orbicularis oris, mentalis and anterior temporal muscles were obtained during swallowing saliva and during swallowing of water with and without the dentures in the mouth.In the different types of swallows recorded, the lower lip and mentalis muscles showed much stronger activity than the upper lip and anterior temporal muscles and also initiated the swallowing activity. No significant changes in mean voltages of the swallowing activity were observed during the 2‐year observation period. On the other hand, the durations of the swallows showed marked increases after 1 year of denture use, when no further rebasings of the complete upper denture had been made.
Signs and symptoms of temporomandibular joint dysfunction in a Saudi Arabian population
Authors: JAGGER R.G. , WOOD C. 
Published: June 2007

Summary The signs and symptoms of temporomandibular joint dysfunction present in 219 Saudi Arabians attending a dental clinic for routine dental treatment are described. Joint sounds (36%) and muscle tenderness to palpation (34%) were common findings. Of the subjects examined, 31% reported suffering from frequent headaches.The study demonstrated a high incidence of signs and symptoms of temporomandibular joint dysfunction. Findings were similar to those of a previous study of an investigation in a bedouin community in Western Egypt (Abdel‐Hakim, 1983).
A comparative study of two methods for the orientation of the occlusal plane and the determination of the vertical dimension of occlusion in edentulous patients
Authors: KOLLER M.M. , MERLINI L. , SPANDRE G. , PALLA S. 
Published: June 2007

Summary The aim of this study was to compare two methods used to orientate the occlusal plane (OP) and to determine the vertical dimension of occlusion (VDO). In method A the VDO was established by means of the rest position, the minimal speaking distance, and the patient's profile. Method B used a newly developed registration pin assembly. The VDO was registered using a silicone occlusion rim and the swallowing technique. The results were compared to the values of the new dentures.Three standardized lateral radiographs were taken at the VDO obtained with methods A, B, and at that of the final dentures. On each radiograph the orientation of the OP to the Camper plane and the VDO were measured by two investigators independently. The results indicated no statistically significant differences between the mean VDO with method A and B compared with the new dentures (P>0.05).With both methods it was not possible to orientate the OP parallel to the Camper plane. None of the occlusal planes of the new dentures were parallel either. Their OP diverged on average by 7° dorso‐caudally.The time spent with method B to orient the OP and to determine the VDO was significantly lower than with method A (17–50min).
Long‐term follow‐up of patients with orofacial discomfort complaints
Authors: YONTCHEV E. , CARLSSON G.E. 
Published: June 2007

SummaryTo a group of 113 patients who exhibited wide variation in orofacial and general complaints, which they related to the effects of dental material, a new questionnaire was sent 8‐10 years after the first examination. Eight patients had died, and 23 individuals could not be contacted. Of the remaining 82 patients, 62 (76%) individuals completed the questionnaire.Almost two‐thirds (29%) of the responding patients reported that they were now free from the previous symptoms, or that these symptoms were alleviated (35%). Dryness of the mouth and smarting tongue were the most frequent symptoms at the follow‐up. Half of the patients (52%) thought they still needed treatment for their complaints, and several of them had visited many other therapists after the end of the treatment period at the Department. The treatment outcome and symptom development may be regarded as acceptable with regard to the severity and long duration of the original complaints. However, the prognosis was poor in a substantial proportion of the patients, and this group continued to be a high consumer of health‐care resources.
The influence of surface finish and in‐vitro pellicle on contact‐angle measurement and surface morphology of three commercially available composite restoratives
Authors: MILOSEVIC A. 
Published: June 2007

SummaryThree commercially available composites (Concise, Occlusin and Heliomolar) had surface finishes of varying roughness. Concise and Occlusin were cured against glass and Mylar, or were polished with a white stone or Soflex discs, producing four different surface finishes. Heliomolar was cured against glass or finished with a Vivadent polisher. Each specimen was immersed in water (without pellicle) or artificial saliva (with pellicle) and photographed with a captive air bubble. The influence of pellicle on contact‐angle measurements and hence adhesiveness was determined. Scanning electron microscopy of pellicle‐free and pellicle‐conditioned surfaces was also performed.The effect of the pellicle on all Concise specimens was profound, tending to increase adhesiveness of the smooth (glass and Mylar) surfaces and decrease adhesiveness of the toughened (white stone and Soflex disc) polished surfaces. The pellicle‐conditioned smooth Occlusin surfaces behaved similarly, but not the polished specimens, having similar contact‐angle measurements after pellicle deposition. Heliomolar had significantly reduced contact‐angle measurements after pellicle formation, and thus increased adhesiveness.The influence of the pellicle on surface finish characteristics may be significant, and may vary according to the composite used.
Thermal diffusivity of glass ionomer cement systems
Authors: BRANTLEY W.A. , KERBY R. E. 
Published: June 2007

SummaryThe thermal diffusivity has been measured for 10 glass ionomer and resin‐based materials: three conventional (water‐hardened) glass ionomer cements, two silverreinforced glass ionomers, an experimental stainless steel‐reinforced glass ionomer, three visible light‐cured (VLC) glass ionomer‐resin hybrid materials, and a VLC resin‐based product developed for the same clinical uses as the hybrid materials. Cube‐shaped specimens, c. 10 × 10 × 10 mm, initially at room temperature were immersed in mercury surrounded by an ice‐water bath. From the experimental cooling curve a semi‐log plot of relative temperature decrease vs. time yielded a straight line whose slope is proportional to the thermal diffusivity. The values ranged from 1.74–5.16 × 10−3 cm2 s−1, and all of the materials tested would have adequate insulating properties provided normal clinical thickness levels for lining materials are maintained. It was found that the thermal diffusivities for the three metal‐reinforced glass ionomers, where composition information is avaiable, do not follow a rule of mixtures applied to the individual components.