bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of stimulus type and stimulus strength on the silent period in human masticatory muscles
Authors: KROON G.W. , NAEIJE M.
Published: June 2007

The silent period in the jaw‐closing muscles of nine healthy subjects was investigated. The stimulus types used were the open–close–clench movement (OCC), the mechanical chin tap and electrical skin stimulation. Irrespective of the jaw‐closing speed for the OCC movements only the unmeasurable and single type silent periods were observed. Increasing the chin tap strength resulted in a decreasing percentage of single type silent periods and an increasing number of depressed, double and merged silent periods. The duration of the short and combined silent period was shorter for the OCC movements than for the chin taps. For the chin taps an increasing stimulus strength resulted in longer silent periods. Only the transition from hard to painful chin tap showed a slight, but significant decrease in short silent period duration. The beginning of the late inhibitory period, which could sometimes be evoked by electrical skin stimulation, coincided with the beginning of the second inhibitory phase of the chin‐tap evoked double silent period. The long silent period as shown by one of the subjects cast doubt on the validity of the relationship between silent period duration and TMJ dysfunction.
Enamel dissolution and fluoride uptake from sugar solutions
Authors: JERUSHALMI I. , MARKITZIU A. , FRIEDMAN M. , GEDALIA I.
Published: June 2007

Solubility studies and fluoride uptake by enamel powder in xylitol‐buffered solutions versus sucrose‐ and glucose‐buffered solutions were carried out. The studies were done at a pH range of 4–8.

The enamel solubility in the xylitol media was similar to the enamel solubility in the other sugar solutions—increasing with a decreasing pH. The solubility of enamel in the buffered sugar solutions was significantly lower as compared to the solubility in the sugar‐free buffered solutions—up to the pH of 6. At the pH values of 7 and 8 the amounts of solubility were similar for the experimental and control solutions.

No significant differences were found in the fluoride uptake by the enamel powder from the fluoride‐containing sugar solutions at the pH values of 6 and 7.5 respectively.

The results point to the conclusion that the xylitol does not differ from sucrose and glucose in its effect on enamel powder solubility and the uptake of fluoride ions by enamel.
Demonstration of chewing motor disorder by recording peripheral correlates of mastication
Authors: STOHLER C. S. , ASH M. M.
Published: June 2007

Chewing motor performance was examined in twenty‐one patients. Twelve patients had TMJ dysfunction syndrome, eight had occlusal trauma, and one had CNS impairment. Surface electromyography and three‐dimensional jaw movement was recorded. Discomfort was recorded by the patient during chewing of beefstick. Specific changes in mandibular movement were related to the presence of pain, discomfort and other symptoms of the TMJ dysfunction syndrome.
The fracture toughness (KIC) of amalgam
Authors: LLOYD C. H. , ADAMSON M.
Published: June 2007

The fracture toughness (KIC) has been measured (at 1 week) for a selection of sixteen amalgam products. This included low copper (i.e. Cu<6%) and high copper (both single component and admixed) products in milled and spherical powder forms. The results have shown that the fracture toughness decreases progressively as the copper content increases. The admixed high copper products possess superior fracture toughness to those containing a single component powder. These results have been attributed to differences in the microstructures produced by changes in composition and form in which the copper addition is made.
The hinge‐axis: a review of the literature
Authors: WINSTANLEY R. B.
Published: June 2007

Study of hinge‐axis opening of the mandible has occupied many distinguished workers over a large number of years. This paper is an attempt to bring all their ideas together into one publication so that readers may reach their own conclusions.
Association between tooth loss and TMJ dysfunction
Authors: KIRVESKARI P. , ALANEN P.
Published: June 2007

An analysis of the distribution of tooth losses in 521 subjects having lost one to fourteen teeth, disclosed a statistically significant association between the loss of maxillary first premolar and the presence of TMJ dysfunction. The association was evident on both sides. Maxillary first premolars have earlier been shown to contact prematurely on hinge closure more often than the other teeth. The loss of other teeth seemed independent of the functional state of the stomatognathic system. It is suggested that TMJ dysfunction may predispose to the loss of the maxillary first premolar by direct trauma to the tooth and/or by speeding up periodontitis.
Pathologic attrition and maximal bite force
Authors: DAHL B. L. , FLØYSTRAND F. , KARLSEN K.
Published: June 2007

The maximal bite force was recorded between antagonizing anterior teeth in a group (n= 10) of patients with pathologic attrition and in a control group. No statistically significant difference between the maximal bite forces was recorded. Also, the effect on the maximal bite force of the continuous wearing of a partial bite raising splint for 4 months was recorded.

The great individuality in reaction patterns prohibited simple generalizations.

However, in some individuals the maximal bite force was larger when biting on the splint than without, both at base line and after 4 months. Also, the maximal bite force showed a tendency to increase with time.

The findings indicate that pathologic attrition is not necessarily associated with a high maximal bite force. Also, the maximal bite force recorded under various conditions is seemingly not an absolute value but rather the result of a number of factors of varying importance for different individuals.
Papillarity of the palatal mucosa
Authors: THOMAS C. J. , KOTZE T. J. V. W. , NASH J. M.
Published: June 2007

A sample of 575 palatal casts was studied and found to possess varying degrees of papillary convolutions between and around the palatal rugae. No palatal appliances were worn and no irritative influence was present. A classification of 1–4 was established and the peak incidence was Class II at 48.4% (Class I, being an absence of papillarity, was 7.3%). It is postulated that the presence of a denture may well cause an inflammatory papillary hyperplasia to arise not by a progression through the various stages of denture stomatitis but directly, in an individual with a papillary palate.
The effect of acrylic bite plane splints and their vertical dimension on jaw muscle silent period in healthy young adults
Authors: FINGER M. , STOHLER C. S. , ASH M. M.
Published: June 2007

A significant question relative to treatment and disappearance of symptoms is raising the bite in combination with a maxillary bite plane splint in patients with TMJ muscle dysfunction. The objective of this research was to investigate the effect, if any, occlusal bite plane splints have on the latency and duration of the menton tap silent period and particularly whether the degree to which the bite is raised is of significance. Recordings were made in healthy young adults from both anterior temporal and masseteric muscles while subjects were clenching at their 70% maximum clenching effort. Placement of a splint significantly (P>0·05) prolonged the silent period duration (SPD). However, mean SPD values taken at two different vertical raised bites did not differ significantly (P>0·05). The anterior temporal muscle SPD was less sensitive to a smaller change of vertical dimension than the masseteric SPD. Silent period latencies remained unchanged in all experimental conditions.
Is food particle size a criterion for the initiation of swallowing?
Authors: LUCAS P. W. , LUKE D. A.
Published: June 2007

A small study on fifteen subjects found that brazil nut particles always broke down much more rapidly per chew than raw carrot particles. Both foods were swallowed, on average, after similar numbers of chews. However, a relationship was found which suggested that subjects that swallowed after few chews took less for carrots than brazils and vice versa for those that took more chews. An extended study with carrot showed a significant correlation between the rate of size breakdown and the number of chews required for swallowing in dentate subjects (r=0.69) but not in full denture wearers. The whole sample (n=79 including six wearers of partial dentures) gave a significant correlation of r=0.65. It is concluded that some consideration of the physical properties (texture) of foods is necessary before results from this type of study can be interpreted as relevant or not for dentistry.
The use of bilateral EMG equalization training in the treatment of temporomandibular joint dysfunction—A case report
Authors: KLONOFF E. A. , JANATA J. W.
Published: June 2007

This paper describes a single‐subject experiment testing two methods of using EMG biofeedback in the treatment of TMJ dysfunction. Following a baseline period, electrodes were placed on the left and right masseter muscles, and the subject was taught general relaxation of this area using visual biofeedback. Although data supported the conclusion that the subject had indeed learned to relax, this was not associated with any change in the report of pain or dysfunction. Equalization training, the goal being to equalize the levels of EMG in the right and left masseter muscles, was then begun. Once the patient had learned to maintain equal levels of EMG, relaxation was then re‐introduced. This produced substantial decreases in her reported pain, both within the session and averaged across days for the time between sessions. These treatment gains were maintained at 2‐month follow‐up.
Clinical and radiographic observations after 6 years on bridge abutment teeth carrying pinledge retainers
Authors: GUSTAVSEN F. , SILNESS J.
Published: June 2007

A group consisting of 108 bridge recipients (71 female, 37 male) with a total of 114 bridges retained solely (n=40) by pinledges or retained by a combination (n=74) of pinledges and complete crowns was examined clinically and radio‐graphically 6 years after completion. The study was to review evidence of any displacement of bridges as well as the incidence of periapical changes and carious‐lesions of those abutment teeth fitted with pinledges (n=210). The results showed that bridges retained solely by pinledges had become displaced more frequently than bridges retained by a combination of crowns. The failure rates (%/year) for bridges retained solely by pinledges was 2.5% and for bridges with a combination of retainers 0.25%. Three teeth (1.4%) experienced pulp exposure during the preparatory work and 6 teeth (2.8%) had been or had to be rootfilled after 6 years. Carious lesions had developed in 6 abutments (1.9%).
Changes in jaw relations and activity of masticatory muscles in patients with immediate complete upper dentures
Authors: TALLGREN A. , TRYDE G. , MIZUTANI H.
Published: June 2007

A longitudinal radiographic cephalometric and electromyographic investigation was performed on eighteen subjects provided with an immediate complete upper and a partial lower denture. The observation stages were: before final extractions and 7 weeks, 6 months and 1 year after denture insertion. The cephalometric analysis was based on measurements from lateral head films taken in centric occlusion. The EMG activity of the anterior temporal and masseter muscles was studied in postural position, light tapping and in maximal clench.

The changes in jaw and occlusal relationships due to resorption of the edentulous maxillary ridge were slight, the mean decrease in occlusal vertical dimension during one year being 0.7 mm. The EMG clench activity at the pre‐extraction stage, when the patients occluded on a residual anterior dentition, showed low mean values round 100 μV, and a further decrease was observed at the post‐insertion stage. At the 1‐year stage all muscles displayed significant increases to above the post‐insertion level. The jaw muscle activity in light tapping and in postural position generally showed no significant mean changes during the observation period.

The results indicate that preservation of a residual dentition in the lower jaw prevents marked changes in jaw and occlusal relationships and resulting changes in muscle activity.
A modified technique to determine the tear energy of impression materials
Authors: VRIJHOEF M. M. A. , LOURENS F. L. , LEYDEKKERS‐GOVERS G. F. M.
Published: June 2007

A modified method to determine tear energy of impression materials is described. Trousers‐shaped specimens were prepared between two platens. They are different from those used before in that (1) a V‐shaped line is created so as to guide tear growth, and (2) the thickness gradually increases, then remains constant and, ultimately, decreases instantaneously. The specimens were tested at ten different rates between 0.2 and 50cm/min. λ can be computed from the force–time diagram. Six different materials were tested: two condensation silicones, Xantopren regular (Bayer, FRG) and Xantopren light; a polyvinylsiloxane, Reprosil regular (DeTrey, Switzerland); a polysulphide Coeflex regular (Coe, USA); a polyether, Impregum (Espe, FRG); and an alginate, Cavex, Fast Set, Dust Free (Keur & Sneltjes, The Netherlands). Tear strength (in kJ/m2) variations at rates between 0.2 and 50cm/min are as follows: Xantopren regular, 0.37–0.64; Xantopren light, 0.29–0.46; Coeflex, 1.10–5–29; Reprosil, 0.66–1.07; Impregum, 0.62–1.04; Cavex, 0.22–0.37. These values are consistent with those reported before. It might be concluded that the new test method gives reliable tear energy values.
Changes in physical and chemical properties of a dental palladium—silver alloy during metal—porcelain bonding
Authors: PAYAN J. , MOYA G. E. , MEYER J. M. , MOYA F.
Published: June 2007

The hardening ability of a dental palladium–silver (Pd–Ag–Sn–In) bonding alloy has been investigated, and the distribution of the elements along the metal–ceramic interface have been studied by microprobe analysis. The alloy was found to be highly heterogeneous in its ‘as‐cast’ condition, but homogenized alloy was obtained after heating the alloy at 1000°C for 2h. Hardening occurred after annealing at 650°C for 1 h. A longer thermal treatment caused the hardness to decrease (over‐ageing). The change in hardness could be attributed to an internal oxidation phenomenon. The additional elements tin and indium segregated towards the ceramic–metal interface, with a diffusion of indium only into the porcelain. Diffusion of silver in the ceramics, supposed to be the cause of the ‘greening’ of dental porcelains baked on silver‐rich alloys, has not been detected by the microprobe across the interface.
An examination of the surface corrosion state of dental fillings and constructions
Authors: YONTCHEV E. , HÅKANSSON B. , HEDEGÅRD B. , VANNERBERG N.‐G.
Published: June 2007

A group of 115 patients with orofacial complaints has been examined. A new method for intraoral measurement of electrode potentials on the surface of the amalgam fillings and prosthetic constructions has been developed and applied. The possible connections between the measured electrode potentials and patients' saliva properties and their complaints have been discussed. No correlations between measured electrode potentials of the metallic fillings and constructions and important saliva properties could be found. No connections between the measured electrode potentials and the patients' complaints could be proved.
The instantaneous centre of rotation of a fixed unilateral distal extension partial denture
Authors: FEINGOLD G. M. , GRANT A. A. , JOHNSON W.
Published: June 2007

A photographic technique was used to determine the instantaneous centre of rotation of a fixed unilateral distal extension partial denture and the teeth to which it was attached. The teeth involved were the lower canine and first premolar. When the two crowns were splinted together to provide support, both vertical and lateral saddle movement was reduced. Saddle support using only the first premolar produced a centre of rotation in the sagittal plane below the canine crown—which became located anterior to the canine when the two supporting teeth were splinted together. In the coronal plane, canine support produced an axis of rotation buccal to, and outside the confines of, the model; splinting of the canine and first premolar caused the centre of rotation in this plane to be located buccally and superior to the abutment tooth roots. The more posteriorly the saddle was loaded, the greater was the magnitude of the resultant movement.
Physical properties of periodontal dressing materials
Authors: RUBINOFF C. H. , GREENER E. H. , ROBINSON P. J.
Published: June 2007

The purpose of this study was to develop standardized reproducible testing methods for evaluating physical properties of periodontal dressing materials. Three commercial compositions (Coe‐Pak, Coe‐Pak Hard & Fast Set and WondrPak) were studied.

Working and setting times were determined by observing the continuous changes in viscosity via the oscillating rheometer. The 24‐h and 1‐week tensile and shear adhesive bonds to enamel were studied by luting orthodontic lingual cleats with a standard film thickness to the orientated labial surfaces of extracted incisors and pulling them to failure. Dimensional change was studied over a period of 24h using a linear variable differential transformer (LVDT).

The developed testing modalities have greater precision than those previously reported. The concept of ‘bench time’ was developed during which certain materials cannot be handled immediately after mixing.
The fracture toughness of repaired composite
Authors: DHURU V. B. , LLOYD C. H.
Published: June 2007

The fracture toughness (K′IC) at the interface formed between a composite substrate and more recently placed composite has been measured to determine the strength of the repair. The substrate material was 24 h old at the time of the repair and the fracture toughness of the repair was measured 24 h later. Five composite products were selected for repair by using either that particular product or one of the others. Repairs were made to clean fractured surfaces, and these after contamination with artificial saliva. The fracture toughness factor of any repair was significantly less than that for the respective control. The effect of surface contamination proved highly significant and reduced the fracture toughness. An interaction existed between adherend (substrate) and adhesive (addition) materials. Compatibility between these for matrix and initiation chemistries did not appear to be significant.
Safety and antibacterial properties of controlled release SnF2
Authors: TINANOFF N. , SIEGRIST B. , LANG N. P.
Published: June 2007

Two clinical studies were performed to evaluate the safety and efficacy of an intracoronal device for the controlled release of SnF2. SnF2‐polycarboxylate cement, containing approximately 72mgF−, was placed in subjects' molars requiring two‐surface restorations.

In the trial for safety, eight subjects had the restoration in place for 34 days. The salivary fluoride levels were elevated to a mean of 0.3/106. over the experimental period. Urinary fluoride levels were only above baseline levels during the first few days. The restoration's physical properties were adequate; however, subjects experienced gingival irritation in areas where the restoration was contacted with gingiva.

In the trial for efficacy, fourteen subjects had either a SnF2‐polycarboxylate or a placebo restoration placed in a molar tooth during a 2 week period of no oral hygiene. During the experimental period, the control subjects had higher levels of salivary total CFU, Streptococcus sanguis and Streptococcus mutans: while the subjects with the SnF2 restoration had increased S. sanguis and decreased S. mutans levels. No differences in G.I. or PL 1 scores were noted between groups.

Further development of this controlled release system should include using the SnF2‐polycarboxylate restoration in more than one tooth per subject to increase the fluoride reservoir, and not allowing the restoration to contact gingival tissues.
An investigation into the compatibility of some irreversible hydrocolloid impression materials and dental gypsum products
Authors: OWEN C. P.
Published: June 2007

Some alginate impression materials produce rough, chalky, soft surfaces on gypsum casts. This is recognized by various standards, which include tests for an alginate's compatibility with gypsum, and its capacity to record details and impart these to a gypsum cast. These qualities were looked at in this study.

The method used closely followed that laid down by International Standard ISO 1563–1978(E) for alginate impression materials. Ten alginates and seven gypsum products were tested. Using the criteria specified by this Standard, it was found that none of the materials tested was able to record the finest (0.020 mm) line on the test block. However, two elastomeric impression materials tested in the same manner also failed to reproduce this line, as did all the gypsum products when tested directly against the block. These findings cast some doubt on the efficacy of utilising such a fine line in the classification of these materials.

Only thirty‐four of the seventy possible combinations were able to reproduce the 0.050 mm line. Eight combinations reproduced the 0.075 mm line as the finest line, and the remainder (thirty‐eight) failed to record any of the lines.

Some of the alginate materials were treated with fixing solutions of varying concentrations of potassium sulphate and alum. The results obtained varied, sometimes producing marked improvement, sometimes deterioration in the surface quality of the subsequent gypsum casts, despite the fact that none of the manufacturers of the alginates recommended the use of fixing solutions.
A clinical report on the use of glass ionomer cement to restore cervical margin lesions
Authors: KNIBBS P. J.
Published: June 2007

A glass ionomer cement of the powder/water type was used to restore cervical margin lesions. One hundred and fortv‐two restorations were reviewed over a period of 2.5 years.

The material performed well clinically. The appearance of the restorations was good. Surface wear was noticed as time progressed. Nine restorations failed during the study. Failure of restorations was probably due to faults in clinical technique.
Cantilever bridges or removable partial dentures in geriatric patients: a two‐year study
Authors: BUDTZ‐JØRGENSEN E. , ISIDOR F.
Published: June 2007

The purpose of this study was to compare prosthetic, functional and occlusal conditions in twenty‐seven patients treated with distally extending cantilever bridges and twenty‐six patients treated with removable partial dentures (RPD) in the mandible. All patients had a complete upper denture. Mean age of the patients in both groups was about 69 years. The patients were under a supervised oral hygiene care throughout the 2‐year study period. There were 6.9±l.7 mandibular teeth left in the bridge group and 7.5±l.7 in the RPD group and the mean number of posterior teeth (natural teeth/denture teeth/pontics) in occlusion was 4.l±l.l and 7.3±l.4, respectively. During the study period signs and symptoms of mandibular dysfunction became significantly aggravated in the RPD group, P<0.05. A balanced occlusion in the muscular contact position was observed in 90% of the patients in the bridge group and in 76% of the RPD wearers. During the study period the need for dental or prosthetic treatment was negligible in the patients treated with bridges. In the RPD group, twenty‐two teeth were restored with fillings due to caries and in eight patients major adjustments of the sublingual bar were necessary due to irritation of the oral mucosa. This study has shown that treatment with distally extending cantilever bridges in the mandible is a favourable alternative to treatment with removable partial dentures in elderly patients with a reduced dentition.
The effect of function and rest on the amplitude of the TMJ click
Authors: MESSENGER K. L. , BARGHI N.
Published: June 2007

It has been suggested that simple resting and therapeutic exercises may be beneficial in reducing or eliminating clicking on the TMJ during mandibular movements. In the reported experiments the effects of short periods of exercise and rest on the amplitude of the TMJ clicking in non‐dysfunction subjects was recorded and compared. This preliminary study suggests that the TMJ clicking sound is affected unpredictably under different imposed conditions.
Masticatory muscle activity as a function of parafunctional, active and passive oral behavioural patterns
Authors: MOSS R. A. , VILLAROSA G. A. , COOLEY J. E. , LOMBARDO T. W.
Published: June 2007

Oral behavioural patterns have received limited empirical support for their causal role in the development of head and facial pain. The present study was designed to assess electromyographic (EMG) variations in six muscle groups (i.e., bilateral masseter, temporalis and orbicularis oris) as a function of various oral behavioural patterns. A second purpose was to determine whether mandibular movement patterns and specific oral behaviours could be predicted by EMG patterns. Eleven non‐pain subjects followed each of twenty oral behavioural patterns while EMG was recorded. Electromyographic change scores were computed for each behaviour relative to baseline measures. Initial analyses were performed using factorial repeated measures ANOVAS. Using post hoc analyses as general guides, specific EMG criteria were developed for classifying mandibular movements. For most subjects, EMG patterns accurately classified teeth clenching, protrusive/retrusive movements, right movements, left movements and lip movement patterns. Wide individual variations were found among muscle groups for identical behaviours. The association between particular oral behaviours and EMG patterns may explain ‘sinus’ headaches and certain types of facial pain.
Treatment times for adhesive bridges
Authors: CREUGERS N. H. J. , van't HOF M. A.
Published: June 2007

The aim of this study was to collect information about the mean working time needed to accomplish the clinical procedures in applying an adhesive bridge, and to gain an insight into the factors that influence the working time. The study was carried out as part of a clinical trial. One hundred and fifty‐one patients needing one adhesive bridge were selected for this study and divided between five operators. Clinical procedures were carried out following a written protocol. The statistical method consisted of an ANOVA after log‐transformation of the working times. The total mean working time needed to accomplish the clinical procedures for adhesive bridges was 60·7 min (s.d.±16·5 min). The mean working time increased by 30% where the abutment teeth were restored with class II or class III restorations. No influence was found related to: (1) type of bridge (i.e. macromechanical versus micromechanical), (2) type of luting resin and (3) location of the bridge. A significant effect on the working times was found for: (1) operator, (2) tooth preparation and (3) occlusal adjustments. With increasing experience of the operator the median working time decreased by up to 35%. The data from this study are considered as useful basic information for efficient planning in the dental practice and for a further cost‐benefit analysis.
Stress as a factor in muscle and temporomandibular joint pain
Authors: LUNDEEN T. F. , STURDEVANT J. R. , GEORGE J. M.
Published: June 2007

Stress‐induced muscle hyperactivity has been proposed as a major aetiological factor in the production of pain in the muscles of mastication and the temporomandibular joints. In the present study, a total of fifty‐two patients with joint or muscle pain were evaluated for stress with the Derogatis Stress Profile (DSP). The muscle pain group (n=24) had higher clinician ratings of psychological factors, stress and chronicity. The muscle‐pain group also had higher Environmental Stress scores on the DSP, more intense pain, and more activity impairment than the joint‐pain group (n=28). The results of multiple regression analysis suggest an association between pain, depression, and impairment of activity in the muscle‐pain group but not in the joint‐pain group. The overall results further suggest that muscle pain develops at ‘normal’ levels of stress.
A new experimental restoration model in man for studying enamel reactions
Authors: GANGLER P. , HOYER I.
Published: June 2007

A new model of experimental restoration is suggested for testing the marginal imperfections of composite resin, for examining the surface morphology of composite restorations and of sound, etched and remineralized enamel. Enamel‐ dentine samples with standardized cavities and composite restorations were placed on lower removable partial dentures using the etching technique. After 12 and 28 days the specimens were examined in a scanning electron microscope (SEM), operated at 15 kV.

After 12 days the examination of the conventional composite resin by SEM showed extremely rough structures. The use of the enamel etch techniques produces acceptable marginal conditions with tags and some minor gaps. Etching the enamel emphasizes its prismatic structure and reveals the typical pattern of demineralization, involving prism cores and the preferential dissolution of prism peripheries.

After 12 days the SEM appearance of uncovered etched enamel suggested that incomplete remineralization had occurred. After 28 days the mineral recoating, which had progressed further, predominantly involved prism‐orientated repair. The experimental model described here is more accurate, highly standardizable and easily accessible, compared with conventional clinical and replica techniques.
Tooth loss and remaining occlusion in a Dutch population
Authors: BATTISTUZZI P. , KÁYSER A. , PEER P.
Published: June 2007

The aim of this study was to gain a better insight into the tooth‐loss pattern in terms of frequency, location and impaired occlusion. The sample, stratified according to socio‐economic class and age, condisted of 750 subjects. The investigation was done by questionnaire and clinical examination. The non‐response was small (15%). With increasing age, more teeth were missing. In the lower socio‐economic group more teeth were missing than in the higher socio‐economic group. The percentage of totally edentulous persons as well as the percentage of persons with one edentulous jas increased with age. Also, the percentage of antagonistic tooth contacts: first premolar, second premolar, second molar and first molar. In all strata the percentage of antagonistic contacts in the premolar area was larger than in the molar area.
Rehabilitation with removable dentures among the dentate population in Finland
Authors: RANTA K.
Published: June 2007

The information available on the rehabilitation with removable dentures among dentate subjects is contradictory. In the present study, the most common type of rehabilitation was a complete maxillary denture with or without a partial one. Nineteen per cent of men and 27% of women belonged to this category. Partial denture(s) without a complete one were worn by 11% of men and 15% of women.

The odds ratio of having partial denture(s) was significantly higher among women, among people with a medium level of income, with a regular dental attendance pattern, and with a shorter distance to the nearest dental clinic. The presence of a complete denture significantly decreased the odds ratio of having a partial denture. The effect of age was non‐significant in the two youngest age categories.

The odds ratio of having a single complete denture was significantly higher among women, among people with a medium level of income and with a shorter distance to the nearest dental clinic. The presence of a partial denture and belonging to the oldest age bracket decreased the odds ratio significantly. Regularity of use of dental services had a non‐significant effect.
Types of patients with crowns in general dental practices
Authors: LEEMPOEL P. J. B. , van ROSSUM G. M. J. M. , de HAAN A. F. J. , REINTJES A. G. M.
Published: June 2007

Based on data from patient records of 9996 crowns constructed in forty general practices, it is discussed what crown types have been constructed in different patient categories. It was found that female ‘crown patients’ received on average more crowns than male patients. Hardly any difference was found between the average number of crowns the patients with or without reimbursement had received. In the younger patients (< 21 years) more jacket crowns were constructed. The 21–30 year group received more full metal crowns, whereas the oldest group (> 51 years) had more metal‐porcelain crowns.

Sick‐fund patients received more jacket crowns and metal‐porcelain crowns on front teeth, while private patients received more full‐metal crowns.
A method for standardization of silent period measurements in human masseter muscle
Authors: TÜRKER K. S.
Published: June 2007

The effect of bite force and stimulus intensity on the electrically induced SP has been studied. The results from the present study and earlier investigations suggest that the following guidelines should be used in future SP studies.

The electrical rather than mechanical way of stimulation should be preferred since the stimulus parameters and the receptors stimulated can easily be determined.

The sensory perception threshold (T) of subjects should be used when studying and comparing the SP between individuals rather than the actual values of the electrical stimulation since the value of the sensory perception threshold varies from subject to subject.

Rectified and averaged EMG records should be used rather than single raw traces since it is not possible to measure the duration of SPs from single traces.

The subject should be asked to perform 25% of his/her MBF and the BF should be given as a feedback.

A stimulus intensity of about 6T should be used so that small changes in the BF would not affect the SPD.

A jaw separation of about 10 mm should be selected in the subjects with normal overjet (2–3 mm), this being slightly thicker than the average isometric force transducer. The transducer can be brought to this thickness using acrylic resin.

A head rest should be used to keep the head position constant (and hence constant jaw position with respect to the transducer) since the head position alone may change the reflexes elicited in the jaws region.
The recognition of craniomandibular disorders—a comparison between clinical and radiographic findings in eighty‐nine subjects
Authors: BEZUUR J. N. , HABETS L. L. M. H. , LOPEZ V. JIMENEZ , NAEIJE M. , HANSSON T. L.
Published: June 2007

A comparison has been made between clinical and radiographical findings in a study of eighty‐nine patients suffering from craniomandibular disorders. In general it was found that condylar changes were more common in these patients than in earlier studies concerning the severe problems of craniomandibular disorders. A statistically significant correlation between clinical and radiographical findings was found for crepitation with osteophyte formation of the condyle (P<0.01). After clinical separation of the patients into two groups based upon the origin of pain, myogenous versus arthrogenous, no radiographical correlation could be made except for condylar osteophytes. With the clinical method used for separation of patients it was found that the clicking of the temporomandibular joint (TMJ) was more common among myogenous patients (P<0.05); crepitation was more common among arthrogenous patients (P<0.01), as was limited mouth opening (P<0.05) and deviation on opening (P<0.05). Radiographically, the only statistical difference between the two groups was found for osteophyte formation of the condyle, this was more common among arthrogenous patients (P<0.05). As the clinical method has been tested earlier, the results of this study lends support to the idea that conventional radiographical examination is of limited use in the initial diagnostics of craniomandibular disorders. Therefore new alternatives have to be developed.
Medical science and the patient
Authors: RIPPIN J. W.
Published: June 2007

Classification is necessary to most forms of thought, and the scientific method requires particular refinement of this process in order to formulate its laws. But there is nothing fundamental about any classification; its categories are chosen for a particular purpose only, and often at least some of the subjects do not fall readily into any class. Furthermore, since only few of an individual's characteristics are used as classifying attributes, individuals themselves become submerged in the classes, and their individuality lost in the scientific laws that arise therefrom. Desiderata of science and uniqueness are therefore opposed—and they are irreconcilable because absolute knowledge is either non‐existent or unattainable. Thus, the decision as to whether an individual patient is healthy or diseased must be made on the basis of diagnostic laws which, as far as the individual is concerned, are inaccurate and may turn out to be spurious or even meaningless. These laws are therefore only guide‐lines which must be ‘re‐individuated’ in clinical practice. In essence, the individual's health depends on the individual's biology.
The effect of retention grooves on gingival marginal leakage in class II posterior composite resin restorations
Authors: BEN‐AMAR A. , LIBERMAN R. , NORDENBERG D. , METZGER Z.
Published: June 2007

In this laboratory study, the effect of retention grooves in the proximal portion of class II cavities on the marginal microleakage using light‐cured composite resin was examined. The retention grooves were placed at the axio‐facial and axio‐lingual line angles and in the gingival floor of the cavities.

The teeth were restored with Herculite composite resin with etching and dentine bonding and polymerized in two different ways: (i) a single mass of restorative material was polymerized all at once; and (ii) incrementally placed amounts of restorative material were each polymerized separately until the cavity was completely filled.

Marginal microleakage was evaluated by the degree of dye penetration at the gingival margin of the restorations after suitable thermocycling procedures.

It was concluded that marginal microleakage was significantly reduced when the composite resin was placed and polymerized incrementally, and that no advantage was gained from retention grooves with this incremental technique. However, when polymerizing in one single mass of material, retention grooves were found to be necessary in order to reduce marginal microleakage at the gingival wall.
The effect of seating pressure and powder/liquid ratio of zinc phosphate cement on the retention of crowns
Authors: KARIPIDIS A. , PEARSON G. J.
Published: June 2007

The effect of three different powder/liquid ratios of one zinc phosphate cement on the early retention of a standard crown on metal and tooth dies was investigated. Two different seating pressures were evaluated. The results indicate that the effect of variation in the powder/liquid was not significant. The part played by the seating force was significant, the higher seating force resulting in a greater force being required for displacement after 1h. Greater forces of removal were required when tooth dies were used.
A criterion for the selection of artificial posterior teeth
Authors: YOSHIDA K. , OKANE H. , NAGASAWA T. , TSURU H.
Published: June 2007

Mandibular movement and masticatory performance were evaluated in the edentulous patients with an experimental denture using posterior artificial teeth of different occlusal schemes in order to determine the criterion for the selection of posterior artificial teeth.

Lower masticatory performance was observed with non‐anatomic posterior teeth than with semi‐anatomic or anatomic ones regardless of the condition of residual ridge and inclination of the horizontal condylar guidance. The value of the lateral component of the masticatory cycle was closely related to the inclination of the cusp and the value of masticatory performance. This suggested strongly that the component could be a criteria for the selection of the type of the artificial posterior teeth.
The Orthopantomogram®, an aid in diagnosis of temporomandibular joint problems.
Authors: HABETS L. L. M. H. , BEZUUR J. N. , NAEIJI M. , HANSSON T. L.
Published: June 2007

Vertical measurements of the Orthopantomogram® of 152 patients were made for condylar and rami heights. The symmetry between the right (R) and the left (L) side was calculated with the formula: |(R−L)/(R+L)|. A statistically significant difference between the patients of a routine dental group and the patients treated for craniomandibular disorders was found regarding condylar height symmetry.
The recognition of craniomandibular disorders—a comparison between clinical, tomographical, and dental panoramic radiographical findings in thirty‐one subjects
Authors: BEZUUR J. N. , HABETS L. L. M. H. , HANSSON T. L.
Published: June 2007

A comparison between clinical, tomographical, and dental panoramic radiographical findings was made in thirty‐one female patients suffering from craniomandibular disorders (CMD). In general it was found that condylar sclerosis was more common in these patients than in earlier studies. After clinical separation of the material into two groups based upon the origin of pain, myogenous versus arthrogenous, no radiographical confirmation of the differential diagnostics could be made. Regarding vertical condylar asymmetry measured on the Orthopantomogram®, it was found that 74% of the patients with CMD had more than the 3% of asymmetry regarded as within normal limits. It seems that with an increasing severity of the disorder the level of condylar asymmetry appears less. If the interpretation of the findings is correct its conclusion might lead to the recognition of a morphological factor which could contribute to the development of a craniomandibular disorder.
Stress in patients with pain in the muscles of mastication and the temporomandibular joints
Authors: LUNDEEN T. F. , GEORGE J. M. , STURDEVANT J. R.
Published: June 2007

This study examined the role of stress in subjects having combined muscle and temporomandibular joint pain compared to subjects having only muscle pain or only joint pain. It was found that the combined pain (n=39) and muscle pain (n=24) groups had comparable levels of pain intensity and activity impairment. The combined pain group, however, had the lowest level of stress and was rated lower than the muscle group in clinicians ratings of psychological factors, stress and chronicity. The combined pain group and joint pain group (n=28) were found to be comparable in terms of the clinician's ratings. This data does not support the concept of a progression of symptoms from muscle pain to combined muscle and joint pain that would be expected from a stress‐induced muscle hyperactivity model of temporomandibular disorders.
Effect of exposure time on the depth of polymerization of a visible light‐cured composite resin
Authors: BAHARAV H. , ABRAHAM D. , CARDASH H. S. , HELFT M.
Published: June 2007

The effect of exposure time of a visible light source on the depth of polymerization and degree of hardness of a sample of Occlusin posterior composite resin was investigated. The border between cured and non‐cured composite resin was identified by a change in colour and by applying pressure with a scalpel. Knoop hardness tests were performed perpendicular to the long axis of illumination.

The composite resin nearer to the light source underwent more complete polymerization. Increased exposure time resulted in greater depth of cure. The rate of polymerization was greatest in the first 10 s. Maximum hardness measured up to a depth of 1 mm obtained after 80 s of exposure time. At greater depth, a decrease in Knoop hardness was observed. At exposures under 80 s, maximum hardness was not achieved even at a depth of only 1 mm.
The determination of elastic recovery of impression materials at the setting time
Authors: JAMANI K. D. , HARRINGTON E. , WILSON H. J.
Published: June 2007

One of the prime requisites of an elastomeric impression material is that it should possess adequate elastic recovery on removal from undercut areas. Most standard methods of measuring elastic recovery rely on the preparation of specimens in moulds. The specimens are subsequently removed and subjected to compressive or tensile stresses several minutes after the setting time.

The equipment described in this paper has been developed to enable elastic recovery values to be determined at times in the vicinity of the setting time. A shear strain is induced in the material for a short time and the resulting recovery recorded graphically. Results indicate that there is a significant improvement in elastic recovery from just prior to until just after the setting time.
Rigidity of elastomeric impression materials
Authors: JAMANI K. D. , HARRINGTON E. , WILSON H. J.
Published: June 2007

The rigidity of an impression material should be less than a certain value in order that excessive forces are not required when taking impressions of undercut areas. Conversely, the impression should be sufficiently rigid to withstand the weight of stone whilst pouring the cast without distortion.

This paper describes a method of determining elastic modulus values at times as early as the setting time of the material. Results indicate that the elastic modulus values increase from the setting time to 30 min after the start of mix. Values are presented for a representative range of elastomeric impression materials.
The recognition of craniomandibular disorders; condylar symmetry in relation to myogenous and arthrogenous origin of pain
Authors: BEZUUR J. N. , HABETS L. L. M. H. , HANSSON T. L.
Published: June 2007

Sixty‐seven per cent of the forty‐three patients suffering from craniomandibular disorders (CMD) had a vertical condylar asymmetry greater than 3%. After division into two different groups, myogenous and arthrogenous origin of pain, it was found that myogenous patients were younger and showed significantly bigger asymmetry between the vertical heights of the left and right condyles, evaluated on an Orthopantomogram®, than the patients with arthrogenous origin of pain (P<0.05). The mean vertical condylar asymmetry was 9.10% and 4.83%, respectively. It is suggested that the possible triggering morphological condylar asymmetry on the pathogenesis of a CMD should be recognized at an early stage of the disorders development. The use of a screening protocol and an Orthopantomogram® could be of preventive importance in daily practice.
Effects of the porcelain firing sequence on the bond strengths of cements
Authors: KANOY B. E. , FELTON D. A. , WHITE J. T. , BAYNE C.
Published: June 2007

Bond strengths for the retention of ceramic bonded to metal alloys to the tooth structure involve cavity preparation variables, cement variables and ceramic bonded to metal alloy variables. The aim of this work was to evaluate the retentive strength differences between alloy surfaces, unfired and fired, for porcelain alloys retained with different dental cement compositions. The clinical situation was simulated by using standardized tooth preparations, extracted teeth and castings cemented with zinc phosphate and polycarboxylate cements, which were debonded on an Instron. Jelenko O, Cameo, Jelstar and Genesis II alloys were compared unfired and fired to simulate porcelain application. Fired Jelenko O casting alloy cemented with polycar‐boxylate cement produced the greatest bond strength (6.0±1.0 MPa). Polycarboxylate cemented castings had greater bond strengths for all alloys whether fired or not. The only effect of firing was an improvement with Jelenko O alloys produced with, both cements. All of these differences were statistically significant at the P<0.01 level using Tukey's post hoc evaluation. The improvements observed were related to the oxide formation on the internal surfaces of the casting and the ability of polycarboxylate cement to adhere chemically to those layers.