bluuebunny/crossref_metadata_2025 huggingface dataset:
The sagittal condylar movements of the clicking temporomandibular joint
Authors: VAN WILLIGEN J.
Published: June 2007

An analysis of the sagittal condylar pathways in patients with clicking temporomandibular joints is presented in relation to the mechanism of this symptom which is still hypothetical. The condylar movements of five healthy subjects are compared with the pathways of five patients with unilateral or bilateral clicking joints. The results indicate that in the latter group there are clearly perceivable deviations from the movement pattern as found in the group of the healthy subjects.
A comparison of dentine abrasion data generated by radiotracer and surface profilometer methods
Authors: DAVIS W. B.
Published: June 2007

Six toothpastes were despatched to two research stations where a radiotracer method of dentine abrasion measurement is used (British Standards, 1974; Hefferren, 1976) and three research stations where a surface profile method is used (Ashmore, Van Abbé & Wilson, 1972).

Each station measured the abrasivities of the pastes with respect to dentine by their own method.

The ranges of abrasion data were found to be wider from the surface profile method than from the radiotracer method.
Clinical study of a heat‐cured silicone soft lining material
Authors: MÄKILÄ EINO , HONKA OSMO
Published: June 2007

Thirty‐seven mandibular dentures lined with Molloplast B silicone material were examined after they had been worn for 2–8 weeks and 6, 18 and 30 months. The denture wearers were also examined and interviewed.

The colour was found to have become lighter in 46% and turned yellow or brown in 51 %; the denture base had worn through in 24% and there was a failure on bond in 22%; no hardening of the material was noted; 24% of the dentures had broken. An unusual taste was reported by 22% and smell by 14% of the denture wearers; mucosal soreness was noted in 14%; denture stomatitis developed in 48%; hygiene was poor in 61 % and fungal growth was traced in 81 % of the dentures; 73 % of the patients were satisfied with the soft lining.
Mucosal temperature rises following long‐term use of full dentures
Authors: MAEDA T. , STOLTZE K. , USER A. , KROONE H. , JENSEN K. E. , BRILL N.
Published: June 2007

Mucosal temperatures were studied in twenty‐two subjects, who had worn full upper and lower dentures for at least 5 years. By comparing with a group of twenty‐two fully dentate subjects, it was found that in the denture wearers, temperatures were increased significantly in the lower jaw, but not in the upper jaw.
The resistance of superficially sealed enamel to wear and carious attack in vitro
Authors: DAVIDSON C. L. , BEKKE‐HOEKSTRA I. S.
Published: June 2007

The resistance to wear and carious attack has been investigated in vitro for enamel that has been subjected to several stages of the sealing procedure: etching, etching and remineralization in whole saliva and etching followed by sealing. After partial mechanical removal of the sealant, the remaining surface enamel proved to be resistant to carious attack as long as the resin tags were present. An estimation is made of the thickness of the affected layer. Pretreatment with monofluorophosphate has proved to influence the extent of the histological changes due to etching. A discussion on these phenomena is given.
Tissue accumulation of nickel released due to electrochemical corrosion of non‐precious dental casting alloys
Authors: BERGMAN M. , BERGMAN B. , SöREMARK R.
Published: June 2007

Specimens of four non‐precious dental casting alloys intended for use in the ceramicmetal technique were implanted subcutaneously in the neck region of mice. The animals were killed after 5 months. Organs and tissues were tested as regards the concentration of nickel by means of atomic absorption spectrophotometry. The study showed that due to electrochemical corrosion nickel was released from implants and accumulated in some tissues and organs.
Tear energy of elastomers for maxillofacial applications
Authors: GOLDBERG A. JON , CRAIG ROBERT G. , FILISKO FRANK E.
Published: June 2007

The energy necessary to generate a unit area of torn surface was measured for six elastomers with low moduli of elasticity. Four polyurethane materials and two commercial maxillofacial materials were included. The latter had tear energy values between 0.63 and 6.56 erg/cm2, while the polyurethanes ranged from 8.49 to 50.0 erg/cm2. Three of the materials demonstrated non‐Hookian behaviour during testing, violating an assumption of the tear energy analysis. A method of compensating for this discrepancy is described.
X‐ray diffraction and fluoride analysis of enamel powder treated with concentrated phosphoric acid containing sodium fluoride
Authors: GEDALIA I. , BAHAREV H. , KOCHAVI D.
Published: June 2007

Reaction products of enamel powder treated with concentrated phosphoric acid (30% and 50%) containing 0.5‐2% NaF were examined by X‐ray diffraction and fluoride determination.

Fluoride concentration increased according to the level of NaF in the acid; the uptake was highest in the enamel treated with the less concentrated acid.

Hydroxyapatite and fluoridated apatite, dicalcium phosphate are the major reaction products. CaF2 was present in all samples; the amount was reduced at the lowest fluoride concentration (0.5% NaF).
The pulpal response to a direct filling resin without an inorganic filler‐Isopast
Authors: VALCKE C. F. , CLEATON‐JONES P. E. , AUSTIN J. C. , PAIN E. , VIEIRA E.
Published: June 2007

A recently marketed direct filling resin, Isosite, does not have an inorganic filler. This material is offered as a hand‐mixed, two‐paste system (Isopast) and is also available in capsulated form and as an ultraviolet activated sytem. Since it is well known that direct filling resins used hitherto are capable of causing pulpal irritation, especially in deep cavities, the pulpal response to Isopast was investigated. The experimental animals were twenty‐four vervet monkeys (Cercopithecus aethiops). Under general anaesthesia a labial cavity was cut in each of the eight incisor teeth (maxillary and mandibular) of each animal. In each animal two cavities were filled with unlined Isopast, two with Isopast over a lining of calcium hydroxide cement, two with silicate cement and two with zinc oxide/eugenol cement. The animals were killed at intervals of 2, 28 and 56 days. The teeth recovered were decalcified and stained for histological examination. Of the total of 192 specimens sixty‐five were discarded, two because of accidental pulpal exposure, one because of leakage and sixy‐three because of technical defects in the preparation of the material, leaving 126 specimens available for assessment. This was done independently by three examiners who did not know which materials had elicited the reactions observed. It was found that after 2 days unlined Isopast caused more pulpal disturbance than other materials. After 28 and 56 day intervals lined Isopast caused less disturbance than the other materials. The maker's recommendation that linings should be used is confirmed.
Fluoride concentrations in fissure and cervical enamel of unerupted human teeth
Authors: GEDALIA I. , SOLDINGER M. , AZAZ B. , SOSKOLNE W. A.
Published: June 2007

Fluoride concentration of fissure enamel from unerupted third molars was higher than that of the cervical‐lingual but not cervical‐buccal surfaces at a similar depth of the removed enamel. The highest fluoride concentration was found in the fissure enamel due probably to its earlier formation, higher permeability and embedding tissue before eruption.
The rheological properties of polyelectrolyte cements
Authors: WATTS D. C. , COMBE E. C. , GREENER E. H.
Published: June 2007

The rheological properties of two glass ionomer cements, ASPA and Fuji have been investigated. The viscosities of the liquid components of these systems have been found to be Newtonian up to a shear rate of 140 s−1 with values of 0.80 N m−2 s for ASPA and 1.8 N m−2 for Fuji. Capillary viscometry techniques have been employed to study the rheological changes accompanying setting. Both cements appear to behave as power law fluids, becoming progressively dilatant as setting proceeds. The apparent viscosities of the two systems are approximately equivalent displaying values of the order of 50 N m‐2 s, at a shear rate of unity shortly after mixing.
Residual stresses in metal‐ceramic crowns
Authors: DÉRAND TORE
Published: June 2007

Residual stresses in metal‐ceramic crowns were examined in three different ways. First, a mathematical formula was used to calculate the stresses in the cervical part of a crown. Second, plastic models was used where the strains were measured with strains‐gauges. Third, real crowns were used and strain gauges were attached on them. The results indicated that compressive stresses appeared in the porcelain‐metal interface. Compressive stresses were also found on the surfaces of the crowns and tensile stresses perpendicular to the interface.
Stresses in the anchor crowns of a metal‐ceramic bridge in model experiments
Authors: DÉRAND TORE
Published: June 2007

A four‐unit principal model bridge was used. The stresses in the porcelain part of an anchor crown were analysed. When the middle of the span was loaded tensile stresses appeared in the outer surface of the porcelain and compressive ones in the interface. Greater stresses were found when the anchor crown was loaded itself. They were not critical, however, when the gold thickness was > 3 mm.
In vitro studies into the use of denture base and soft liner materials as carriers for drugs in the mouth
Authors: ADDY M.
Published: June 2007

The potential of plasticized and polymerized acrylics to carry and release medicaments was investigated. Chlorhexidine acetate was incorporated at concentrations of 2, 5 and 10% into the powder phase of heat and cold cured acrylics and an acrylic gel soft liner. A preliminary bioassay demonstrated comparable release at anti‐bacterial levels from all three materials. Spectrophotometric and agar diffusion measurements of the chlorhexidine released into water showed the duration increased with the concentration of chlorhexidine incorporated. At 10% admixture the release from the polymerized and plasticized acrylics was in excess of 100 days. Light and scanning electron microscopy of polished and fractured surfaces of the polymerized acrylic showed the chlorhexidine distributed throughout the matrix of the materials. Following soaking in water, holes appeared in the matrix, particularly in the surface zones. Sections of the acrylic gel soft liner demonstrated chlorhexidine distributed as particulate material. Soaking in water caused vacuolation of the material and at higher concentrations material break‐up was apparent.
Facial pains and the jaw muscles: a review
Authors: CHRISTENSEN L. V.
Published: June 2007

A review is given of some of the major symptoms and signs of facial pains presumed to have their origin in the jaw muscles; that is, the temporomandibular joint pain dysfunction syndrome, the myofascial pain dysfunction syndrome or the mandibular pain dysfunction syndrome.
Instrumental colour measurement of vital and extracted human teeth
Authors: MACENTEE M. , LAKOWSKI R.
Published: June 2007

The Gamma Scientific 2400T telespectroradiometer and the Zeiss RFC3 abridge spectrophotometer gave comparable colorimetric values when analysing extracted teeth and Johnson Grey Tiles. The colour of vital teeth is influenced by the surrounding oral environment. The C.I.E. chromaticity of vital teeth and extracted teeth reported here differs significantly from the colour of teeth reported by other investigators.
Fluoride release from a fluoride‐containing amalgam, a glass ionomer cement and a silicate cement in artificial saliva
Authors: TVEIT ANNE BJØRG , GJERDET NILS ROAR
Published: June 2007

This study aimed to compare the fluoride release from a flouride‐containing amalgam, a silicate cement and a glass ionomer cement in artificial saliva. After storing specimens in an artificial saliva for 7 weeks, the fluoride content in the solvent was measured by a spectrophotometric method. The fluoride release from silicate cement was about 5 times greater than from glass ionomer cement, which again showed a release 4 times greater than the fluoride‐containing amalgam. The fluoride release relative to fluoride content in test specimens was greater from fluoride‐containing amalgam and silicate cement than from glass ionomer cement.
The effect of bite force on the duration and latency of the menton tap silent period
Authors: PALLA S. , Jr BAILEY J. O. , GRASSL H. , Jr ASH M. M.
Published: June 2007

The purpose of this research was to investigate the effect of bite force changes on the duration and latency of the menton tap silent period and particularly whether a decrease in bite force can increase the duration of the silent period to the extent which may be found in dysfunctional patients. The menton tap silent period was recorded from both anterior temporal and masseter muscles while the subject was clenching at different force levels. A bilaterally stable force transducer was used to monitor the clenching force. The results indicated no statistically significant differences in the mean durations and latencies of silent periods at different clenching forces. They suggest that duration and latency are not related to the degree of clenching force.
Nocturnal masseter muscle activity and the symptoms of masticatory dysfunction
Authors: CLARK GLENN T. , BEEMSTERBOER PHYLLIS L. , RUGH JOHN D.
Published: June 2007

This study evaluated the level of nocturnal masseter activity and the symptoms of jaw dysfunction in eighty‐five subjects who varied with respect to degree of jaw dysfunction. A combined jaw dysfunction index was employed which evaluated both the patients subjective report of pain as well as the clinical examination evidence of jaw dysfunction. Using this combined index, a significant correlation was found between the level of nocturnal masseter activity and the signs and symptoms of jaw dysfunction. Tooth wear was also related to signs and symptoms of jaw dysfunction as well as high levels of nocturnal masseter muscle activity (bruxism).
Some advances in endosseous implants
Authors: LAVELLE C. L. B. , WEDGWOOD D. , LOVE W. B.
Published: June 2007

A major advance in endosseous implantology hinges on the coating of titanium implants by porous biodegradable, bioreactive tricalcium phosphate ceramic. When implanted into alveolar bone by a careful technique, the ceramic is resorbed to be replaced by bone. As a result, the endosseous implant becomes ankylosed to the bone. This represents a stable implant/bone interface as opposed to the unstable connective tissue interface that encapsulates many other implant devices.
The tooth‐amalgam interaction
Authors: SARKAR N. K. , Jr FUYS R. A. , SCHOENFELD C. M. , ARMSTRONG L. M. , STANFORD J. W.
Published: June 2007

The interaction between tooth and amalgam during in vitro corrosion of dental amalgams has been studied in this investigation. Extracted teeth have been restored with five commercial amalgams, one of which was γ2‐free and the others contained the γ2‐phase. The restored teeth were immersed in a 1% NaCl solution for 9 months. Post‐corrosion restorations have been examined by optical microscopy, scanning electron microscopy, and X‐ray microanalysis. The results are: (1)γ2‐containing amalgam surfaces were covered with Ca‐Sn‐P‐rich corrosion products of various morphology which occasionally contained relatively low concentrations of Cl and/or Zn; (2) the corrosion products on the γ2‐free amalgam surface indicated relatively high concentrations of Hg in addition to Ca, P, Sn, Cu, and Zn. These results agree with the past observations that corrosion of amalgam restorations is not an isolated process. Rather it may involve reactions of the restoration and the surrounding oral environment including tooth and oral fluids in which interactions of Sn, Zn, Hg, Ca and P take place.
Induced growth of the mandibular condyle in the rat
Authors: BUCHNER R.
Published: June 2007

Advancement of the calcification front in the cartilage, which is a measure of the growth of the cartilage, can be determined by the administration of two dose bone‐markers at specific intervals. It appears that growth still takes place in animals of 12–18 months. This growth is possible by the persistence of chondrogenic cells. The overall growth of the central part of the condyle amounts to about 2 mm over the period from 2 to 18 months.

Raising of the bite in the rat has an obvious influence on the temporomandibular joint, and on the condyle in particular. Within a few days an increase of growth‐rate of cartilage can be demonstrated. This extra growth is temporary, and the intensity and duration of the response is determined by the age of the animal. This adaptation is related to the presence of chondrogenic cells in the cartilaginous layer in the condyle.
Analysis for establishing chronological age of bone
Authors: MEIR E. , GEDALIA I. , SMITH P. , MAYER I.
Published: June 2007

An examination was carried out of the range of variations in the chemical components of human bone dating from 2100 to 2000 bpe.

A comparison was made with bones of other ages. A definite connection was established in the samples, between the percentage of inorganic material and the age of the bone.
The use of glazing materials for finishing dental composite resin surfaces
Authors: LAMBRECHTS P. , VAN HERLE G.
Published: June 2007

The purpose of this study was to investigate the retention of glazes on polished composite surfaces. Sections of three differently resin‐coated composites have been prepared in vitro and examined by scanning electron microscopy (SEM). All samples showed an interrupted interstice between glaze and composite. After ultrasonic cleaning of the composite surface, the empty porosities do not provide enough mechanical retention to retain the glaze. The difference in physical properties of both components may explain the releasing of the sealant. Surface conditioning with H3PO4 (37%) enhances the mechanical retention on coarse‐grained composites. The same effect occurs using chloroform. This chemical also realizes a partial chemical bond. However, it has been proved to be insufficient to prevent glaze releasing. Consequently, the use of glazing materials seems unsuitable for a permanent gloss on composite surfaces.
A more efficient biofeedback procedure for the treatment of nocturnal bruxism
Authors: MOSS ROBERT A. , HAMMER DAVID , ADAMS HENRY E. , JENKINS JACK O. , THOMPSON KEVIN , HABER JOEL
Published: June 2007

This study describes a novel approach in the use of a conditioning procedure for the treatment of nocturnal bruxism. The effectiveness of the procedure is demonstrated through its application with two nocturnal bruxists in controlled case study designs. Subject 1 received several variations of this procedure and the results indicated that using a loud tone which she manually reset after awakening was the most effective approach to this treatment. The second study was designed to compare the effectiveness of relaxation training to the conditioning technique. Subject 2 failed to show any decrease in her bruxing behaviour when taught relaxation. However, she showed immediate decreases in both frequency and duration of bruxing responses when treated with the biofeedback procedure. The need for future research in this area is discussed with emphasis on the development of low cost, home treatment units.
The fracture toughness of dental composites
Authors: LLOYD C. H.
Published: June 2007

A fracture mechanics approach has been adopted to quantify the failure of dental composites under stress. The parameter KIC has been determined by the use of SEN specimens subject to the variables of composite product type, storage environment, test environment and temperature, and polymerization time. The results show that KIc varies from product to product, increasing significantly if there is sufficient time for the absorption of storage water. The effect of test environment and temperature (over the range expected in vivo) is minor.
Observation and comparison of polished composite surfaces with the aid of SEM and profilometer
Authors: LAMBRECHTS P. , VAN HERLE G.
Published: June 2007

Fourteen different composites were polished in vitro with Sof‐lex® 3M discs. The results were examined clinically, with SEM, and profilometrically. According to the clinical study the different materials were divided into three groups. Group A consisted of five composites, that could be polished up to a fair gloss. Group B contained five composites, where only a semi‐gloss could be obtained. Group C contained four products, whose surfaces remained dull after whatever polishing procedure. The SEM study affirmed these results. The products of group A showed smooth and homogeneous surfaces; hence their name: smooth‐surface composites. The products of group B can be considered as classic composites. Group C contains among others the glass ionomer cements. The profilometrical study pointed out that the roughness degree of group A was three times smaller than that of group B and five times smaller than that of group C. The polishing procedure was further analysed. Polishing material, technique and time are the most important factors in the finishing of composite fillings.
The utilization of roots to carry post‐retained crowns
Authors: TURNER C. H.
Published: June 2007

A retrospective study of 5‐year‐old post‐retained crowns made using a matched reamer/sprue technique, was carried out. Standardized radiographs enabled the length of post within the root to be compared with the maximum available length, and this was related to the success of the restoration. Six posts (11.5% of the sample) had become dislodged, of which four were successfully re‐cemented.

The range of root utilization varied from 46 to 137% of the calculated ideal maximum length, indicating that radiographs or measurements were not used routinely as an aid to root preparation, and in some cases the integrity of the apical seal had been severely prejudiced. Despite some very short posts, no roots had fractured. The minimum length of post which ideally should be used has been calculated as 9 mm.
A procedure to achieve controlled pulp exposure: an explorative experiment
Authors: THÉ G. S. T.
Published: June 2007

The present paper reports the development of a method by which controlled pulp exposure can be achieved. Buccal cavities in teeth of adult monkeys were prepared by very slow intermittent cutting, using air as a coolant. During each intermission the electrical resistance of the tissues was measured by means of direct current. One electrode contacted the gingiva and the other was the bur itself. The resistance values were related to observations in histological sections of the teeth. Under the conditions described, pulp exposure occurred at an electrical resistance of about 10 mega‐ohm (Mω).
Long latency components of the jaw jerk and blink reflex in man
Authors: WIDMALM SVEN‐ERIK
Published: June 2007

In the present study, the electromyographic (EMG) activity in the masseter and temporal muscles during about 200 ms after chin taps (jaw jerk response) was compared with the EMG activity in the orbicularis oculi after glabella tap (blink reflex). In two of ten subjects components with long latency and duration, analogous to blink reflex components BR2 and BR3, were found in the masseter and temporal muscles. They may represent the mechanical contraction which results in jaw closure.

In two of the subjects chin taps were found to elicit late responses in the orbicularis oculi with the same latencies (25–30 and 80–100 ms) as BR2 and BR3 associated with glabella tap.
Relationship between dental state and dietary intake in 70‐year‐old males and females in Göteborg, Sweden: a population study*
Authors: ÖSTERBERG T. , STEEN B.
Published: June 2007

A representative sample of 368 70‐year‐old males and females in Göteborg, Sweden, participated in an odontological examination and a dietary interview. The aim of the study was to relate dental state to dietary habits and, furthermore, to study the possible influence of some social factors on these relations. The degree of dental invalidity was measured with Eichner's index. There was a highly significant correlation between this index and the number of teeth and tooth contacts. Dietary interviews were performed by a dietitian according to the dietary history method. Intake of several food items was significantly inversely related to the degree of dental invalidity in males but less so in females. The proportion of probands with insufficient intake of nutrients was in one or more respects higher among the edentulous than in the dentate and highest in the female edentulous probands with only one or no denture.

Insufficient intakes of some nutrients were significantly related to the degree of dental invalidity. These relations remained unchanged in males but not in females when some socio‐economic factors were introduced as confounding factors in a multivariate relation analysis; which might be due to the fact that these social factors play a more important role in females than in males.
The comparative efficacy of relaxation training and masseter EMG feedback in the treatment of TMJ dysfunction
Authors: MOSS R. A. , WEDDING D. , SANDERS S. H.
Published: June 2007

The present series of single case studies was designed to evaluate the comparative efficacy of masseter EMG feedback with progressive relaxation training in the treatment of TMJ dysfunction. Study 1 employed a multiple baseline design across the symptoms of jaw pain, jaw tension and shoulder pain in a patient with chronic TMJ problems. The results indicated that relaxation training was the treatment responsible for improvements in subjective ratings of jaw pain and tension, whereas masseter EMG feedback provided little additional benefit. Trapezius EMG feedback was necessary to provide improvements in ratings of shoulder pain. Study 2 consisted of four single case designs in which masseter EMG feedback and relaxation training were compared with four TMJ patients. Results indicated that relaxation produced clear improvements in pain and tension ratings for two patients, a combination of EMG feedback and relaxation training resulted in slight improvements in one patient, and neither treatment procedure was effective for the final patient. The possibility of wide‐scale application of relaxation training with TMJ patients and the need for further controlled research of masseter EMG feedback were discussed.
Tooth contact patterns and contractile activity of the elevator jaw muscles during mastication of two different types of food
Authors: MOHAMED S. E. , CHRISTENSEN L. V. , HARRISON J. D.
Published: June 2007

The pattern of molar and canine contacts and the contractile activity of the masseter and anterior temporal muscle were studied, through integrated electromyography, during right‐sided mastication of banana and apple in ten healthy male subjects. Tooth contacts occurred on both the chewing and the non‐chewing side. This study does not support the clinical concept that non‐chewing side contacts are necessarily detrimental to the jaw muscles and the temporomandibular joints. The activity of the elevator jaw muscles and the tooth contact patterns suggest that the mandible tilted around a sagittal axis, and rotated around a vertical axis, during the phase of elevation of a masticatory cycle.
The chloride corrosion behaviour of four orthodontic wires
Authors: SARKAR N. K. , REDMOND W. , SCHWANINGER B. , GOLDBERG A. J.
Published: June 2007

Potentiodynamic cyclic polarization of four orthodontic alloys (wires), namely Permachrome, Elgiloy, a β‐titanium alloy and Nitinol in a 1 % NaCl solution within −500 mV and +300 mV (SCE) indicated the first three alloys to be passive whereas breakdown of passivity was observed on Nitinol. The SEM examination of the pre‐and post‐polarized alloy surfaces provided evidence which was consistent with the electrochemical measurements, in that the first three alloys exhibited no appreciable corrosion damage whereas pitting corrosion was observed on Nitinol.

The results obtained from X‐ray analysis of the pitted surface indicated that this pitting could be due to selective dissolution of nickel from Nitinol.
The abrasion of acrylic resin by cleaning pastes
Authors: HEATH J. R. , DAVENPORT J. C. , JONES P. A.
Published: June 2007

The physical removal of plaque from dentures by brushing is important in the maintenance of oral health. However, there is a danger that brushing will abrade acrylic resin. A machine using a rotary brushing action was therefore utilized for laboratory tests of possible cleaning pastes, employing a toothbrush with good access and adaptability to denture surfaces. Crest toothpaste produced the most abrasion on acrylic resin, Dentu‐Creme the least. An experimental paste produced an appreciably lower abrasion rate. Self‐cured specimens wore more than heat‐cured ones. The rate of abrasion decreased as the temperature was raised. Brushing with water alone, or with a 10% solution of soap, did not produce detectable wear.

The wear produced by proprietary cleaners when hand brushing the lingual flanges of dentures and flat blanks of heat‐cured acrylic was also measured. Boots denture cleaning paste produced the greatest abrasion, Dentu‐Creme the least. The wear measured by reference to a glass plane was at least twice that recorded by the decrease in depth of a groove. The machine did not quantitatively produce the same abrasion as hand brushing, nor did it qualitatively rank the pastes in the same order of abrasiveness.

The clinical relevance of these results is discussed.
Intra‐radicular hydrostatic pressure changes during the cementation of post‐retained crowns
Authors: GROSS M. J. , TURNER C. H.
Published: June 2007

The intra‐radicular hydrostatic pressures generated during the cementation of parallel‐sided dental posts have been measured. Pressures are generated only when cement is inserted into the prepared post hole. Using zinc phosphate cement, with posts placed 2 min from the commencement of mixing, pressure has been shown to depend on post diameter, the closeness of fit, and the powder‐liquid ratio. The maximum pressure recorded was 1.7 × 104 kN/m2 using a 1.3 mm diameter post, a mean cement film thickness of 37 μm, and an ideal powder‐liquid ratio of 3.0. Pressures similar to that generated using zinc phosphate cement were recorded when black copper phosphate was used as the lute, but zinc polycarboxylate generated less pressure, and an ortho‐ethoxy benzoic acid cement markedly less pressure.

Before it is possible to confirm the ideal luting cement for posts, further studies of the effectiveness of cement release channels, and post retention. are necessary.
Geographic comparisons of the incidence of dental erosion: a two centre study
Authors: XHONGA FRIDA A. , VALDMANIS SILVIA
Published: June 2007

This study revealed that the premolars in both arches are most commonly afflicted with erosion. The same results were obtained in an earlier study conducted by Sognnaes, Wolcott & Xhonga (1972) and Xhonga, Wolcott & Sognnaes (1972) evaluating the erosion pattern on extracted teeth. These findings should be helpful in further investigation into the aetiology and treatment.

Educational, epidemiological and preventive concerns derive from a study establishing the dental erosion frequency on a large population sample (approximately 600 individuals and 1500 teeth). The comparative results for both locations used will provide a more significant basis for future studies of a similar nature.
The determination of free‐way space in edentulous patients: a cephalometric approach
Authors: POTGIETER PIETERJ. , MONTEITH BRIAN D. , KEMP PIETER L.
Published: June 2007

This study was prompted by the hypothesis that the contractile power of the masseter and medial pterygoid muscles influences not only the shape of the gonial angle of the mandible into which these muscles insert, but also that they play a major part in determining the amount of free‐way space present in any individual.

Tracings were made from the lateral cephalograms of 130 dentate subjects and the gonial angle measured in each case. Free‐way space was also measured, using a dakometer, and the paired values subjected to statistical analysis. A strong inverse correlation was found to exist, indicating that throughout the sample a decrease (or sharpening) of the gonial angle is accompanied by a predictable increase in the free‐way space. By applying the processes of linear regression to the paired results, a formula was obtained which may be used to predict the best value of one variable for any given value of the other. Thus, in an edentulous case, where the value of the free‐way space measurement is unknown, a method is provided for predicting its best value by the determination of the patient's gonial angle through cephalometric analysis.
Computer graphic representation of mandibular movements in three dimensions: the method
Authors: KNAPP JOHN G.
Published: June 2007

A mathematical simulation of the Denar D4A articulator and a simulated complement of graphically represented teeth were programmed in a Prime 4000 minicomputer. The computer program could be manipulated to quantitatively evaluate the theoretical effects of changes in articulator and control factors on the anatomy of selected teeth or tooth groups. The effects of these changes could be assessed graphically and numerically and data could be manipulated statistically.
Alteration in directional specificity of interdental dimension discrimination with the degree of mouth opening
Authors: MORIMOTO T. , HAMADA T. , KAWAMURA Y.
Published: June 2007

The interdental dimension discrimination (IDD) ability was tested at seven different degrees of mouth opening: 40 mm, 30 mm, 20 mm and 10 mm openings for the dentate subjects, and 10 mm opening, intercuspal position (ICP) and the ICP minus 5 mm for the edentulous subjects. The subjects were asked to discriminate between pairs of sticks held alternately between the upper and lower incisors. The IDD ability, evaluated in terms of the 50% difference limen (DL), did not differ significantly between any two of the tests conducted at seven different openings, although the number of misjudgments of the dentate subjects tended to increase with the degree of mouth opening. On the other hand, the directional specificity of the IDD, which is a tendency to overestimate the dimension of the first stick of each pair, developed almost linearly with a decrease in the opening degree. These findings indicate that the behaviour of the receptors concerned varies with the intermaxillary distance. Some edentulous subjects could not perceive the presence of a small test stick at the overclosed position (ICP ‐ 5 mm), but vibration applied to the mandible enabled the subjects to detect the stick at the same opening. These results support the assumption that the muscle spindles of the jaw‐closing muscles are the receptors responsible for the IDD.
Phenomenological model of creep of dental amalgam
Authors: VRIJHOEF M. M. A. , LOURENS F. L. , LEIJDEKKERS‐GOVERS A. F. M.
Published: June 2007

Earlier work revealed that creep of a particular dental amalgam can be described by the model F(t)=F0 exp (t/t0)m. Here F(t) is the creep compliance at time t, whereas F0, t0 and m are constants of the model. In the previous study only three alloys were used. It was the aim of this study to investigate the factor alloy more thoroughly. After specimen preparation, the nineteen different amalgams were aged at 37°C for either one day or one week. Then creep was determined at a temperature of 22.5°C and a compressive stress of 117 MN/m2.

F
0 turns out to depend upon both the ageing time as well as on the choice of the alloy. As expected, t0 shows up substantial differences between the respective amalgams, whereas the differences between the two ageing are absent or relatively small. The factor alloy significantly influences m. However, the ageing time exerts no significant influence upon m.
Initial physical tests of aluminoborate cements in the context of periodontal dressing development
Authors: WATTS TREVOR L. P. , BERTENSHAW BARRY W. , COMBE EDWARD C.
Published: June 2007

A new glass ionomer cement system (aluminoborate) is under consideration for dental applications, including the possibility of a periodontal dressing material. Following the development of pertinent adhesive and rheological tests, two experimental formulations were selected by a simple screening procedure and subjected to appropriate adhesive tests. One formulation proved satisfactory and was subjected to a rheological test in addition. The possible role of aluminoborates as periodontal dressing materials is discussed.
Stomatognathic dysfunction in the western desert of Egypt: an epidemiological survey
Authors: ABDEL‐HAKIM A. M.
Published: June 2007

Results of a study of 215 male subjects from Siwa oasis are presented. The Siwian community is representative of the Bedouin communities in the Egyptian western desert. The population belongs to a characteristic ethnic group, living in a primitive way. The most prevalent symptoms were headache (29%), pain in the ear (24%) and clicking joint sounds (19%); 84% of the subjects suffered from tenderness of one or more of the masticatory muscles; 8% of the subjects had painful movements of the mandible.

The results extend knowledge of the distribution of jaw dysfunction complaints into hitherto uninvestigated communities.
A comparison of photoelastic and finite element stress analysis in restored tooth structures
Authors: de VREE J. H. P. , PETERS M. C. R. B. , PLASSCHAERT A. J. M.
Published: June 2007

Two methods for determining internal stresses in tooth structures were compared under a specific load condition. The numerical method of the finite element method has a definite number of advantages over the experimental photoelastic method. The numerical results obtained by the first method are in reasonable conformity with those obtained by the latter. In addition the sensitivity of the finite element method towards variation of a number of relevant parameters has been studied.
Salivary flow, saliva, pH and buffering capacity in 70‐year‐old men and women
Authors: ÖSTERBERG T. , LANDAHL S. , HEDEGÅRD B.
Published: June 2007

A representative systematic selection of 30% of all 70‐year‐olds (1148 persons) in Göteborg were invited to a population study. The participation rate was 85%. Sixteen per cent of the men and 25% of the women reported dryness in the mouth (sex. diff.P<0.01). There was a significant correlation between the number of drugs consumed by the subjects and subjective dryness (in both sexesP<0.001). Intake of drugs from the groups of anticholionergics, antihistamines, sedatives, hypnotics or phenothiazines respectively seemed to have the highest predicative value for dryness in the mouth (menP<0.05 and womenP<0.01). There was also a positive correlation between subjective dryness and number of definable diseases in both sexes (P<0.01). In a consecutive sample (fifty‐eight men and fifty‐three women) a study of salivary flow, direct pH and buffer effect were performed. The mean value of unstimulated salivary secretion was in men 0.25 and in women 0.18ml/min. Corresponding figures for stimulated secretion was 1.65 and 1.04ml/min (sex. diff.P<0.01).

A significantly lower unstimulated secretion was noted in women with subjective dryness (P<0.01).

A negative significant correlation were found between dental invalidity, according to Eichner's classification, and stimulated secretion when drug treatment had been considered (menP<0.05 and womenP<0.01). Only weak relations were noted between salivary secretions and drug treatment. Only intake of drugs with diuretic effect were negatively correlated to stimulated secretion (P<0.01). Diseases of the circulatory system were correlated to subjective dryness (P<0.01).
Occlusal adjustment under the control of intra‐oral recording with the aid of the functiograph
Authors: KLEINROK MARIA
Published: June 2007

Objective diagnosis of occlusal relationships is possible with the aid of a new instrument called the ‘Functiograph’. It enables recordings of both the free and tooth‐guided mandibular movements to be made intra‐orally on the same tracing plate. A series of twenty cases has been undertaken and a number of selected examples are illustrated.

Occlusal equilibration under the control of tooth‐guided movement records enables the estimation of the results of occlusal correction in an objective and methodical way.
Bacteria‐tight sealing of exposed dog pulps
Authors: VAN WEELDEREN M. WIJNBERGEN‐BUIJEN , VAN MULLEM P. J.
Published: June 2007

Penetration of bacteria past filling materials can interfere with the vitality of exposed pulps. In the present study, seventy‐three dog's teeth were filled – after exposure – with Cavit‐W and then sealed either with a chemically or a UV polymerizing bonding.

After 14 days a failure rate of 28% was demonstrated using the chemically polymerizing Concise and of 4.5% using the UV polymerizing Uvio‐Bond. After 42 days the latter bonding revealed a success rate of 100%.

To achieve a bacteria‐tight seal of deep cavities for middle long term animal experimentation, Uvio‐Bond can be used – after etching – to cover the filling material and the surrounding enamel.
The assessment of personality, anxiety and depression in mandibular pain dysfunction subjects
Authors: MOSS ROBERT A. , ADAMS HENRY E.
Published: June 2007

The search for distinct personality characteristics of mandibular pain dysfunction patients has produced confusing and contradictory results. The present study represents an attempt to clarify this area of research by assessing reliable measures of personality (MMPI), anxiety (Speilberger State‐Trait Anxiety Inventory), and depression (Beck Depression Inventory) in ten subjects with a history of facial pain and TMJ sounds. Two control groups, one with TMJ sounds only and other with no history of these symptoms, were matched for sex. The results indicated that the groups did not differ on any of these measures. Discussion focuses on possible explanations for the failure to find any differences in these measures and the future of personality assessment in mandibular pain dysfunction populations.
The transverse strength of acrylic resin strips and of repaired acrylic samples
Authors: GRAJOWER RAFAEL , GOULTSCHIN JOSEF
Published: June 2007

A method was developed for measuring the transverse strength of repaired acrylic samples at a single butt joint. The strength was determined for samples prepared from two types of heat polymerizing resins and two types of repair resins. The temperature elevation during curing of the repair resins was determined. Cross‐linking of the resins was evaluated by immersion of samples in solvents. The appearance of the bead microstructure after various treatments was considered to indicate relaxation at the sample surface. Repaired samples of the heat polymerizing resin which exhibited relaxation after immersion in monomer, had a lower strength than samples prepared from the resin for which relaxation was not observed, although both resins were cross‐linked to a similar extent. The application of pressure during curing increased the strength of the samples repaired with the rapid curing, cross‐linked, repair resin. The strength of the samples repaired with the uncross‐linked, slow curing, repair resin was affected by pressure only if the insertion of the repair resin between the sample parts was delayed after mixing. Variations in the powder to liquid ratio of the uncross‐linked repair resin did not affect the sample strength. Wetting of the sample parts with monomer before repair, and variations in the curing temperature did not affect the sample strength for the investigated resin combinations.
A standardized system for evoking reflexes in human jaw elevator muscles
Authors: MURRAY G. M. , KLINEBERG I. J.
Published: June 2007

A standardized reproducible system for evoking jaw reflexes following chin tap is described. It represents an improvement over non‐standardized and other standardized forms of instrumentation in that characteristics of the associated jaw displacement and parameters of the evoked jaw jerk reflexes recorded using this system have been shown to be reproducible. The need for standardized instrumentation to evoke jaw reflexes of any kind is emphasized by the influence of graded variations in tap force on the parameters of the evoked jaw jerk reflex response. Thus, higher levels of tap force correlate with an increased jaw jerk duration and amplitude and a decreased latency.
Interdental thickness discrimination in myofascial pain dysfunction subjects
Authors: CLARK G. T. , JACOBSON R. , BEEMSTERBOER P. L.
Published: June 2007

Interdental thickness discrimination (ITD) was evaluated on twenty‐eight normal subjects and twenty subjects with myofascial pain dysfunction (MPD). This evaluation was performed before and after a submaximal isometric clenching task sustained to pain tolerance. The results of the study demonstrate a significant difference in ITD ability at several test points between the normal and MPD subjects. The experimental variable of sustained submaximal clenching did not significantly alter the ITD ability of either subject group.
Human discrimination of different bite forces
Authors: WILLIAMS W. N. , LA POINTE L.L. , BLANTON R.S.
Published: June 2007

Twenty young adult subjects were selected to determine normal baseline data of dynamic interdental bite force discrimination by use of a specially designed strain gauge instrument. The data may aid in defining the role of the periodontal ligament, temporomandibular joint and muscles of mastication in the regulation of interincisor bite force.
The relationship of lining thickness and thermal insulating efficiency
Authors: JEFFREY I.W.M.
Published: June 2007

The minimum thickness of a lining material that must be inserted into a cavity in order to afford protection to the dental pulp from thermal trauma has never been determined. By taking the diffusivity ratios of the hard dental tissues, amalgam and lining materials and equating them with the situations incurred in the transmission of thermal energy by the unfilled, as against the restored tooth, it becomes possible to produce a simple table from which measurements serving as guidelines for adequate protection can be taken. An experimental method of confirmation of the hypothesis is described.
Guiding sleeve tilt angle in paralleling instruments
Authors: MöLLERSTEN LENNART
Published: June 2007

To investigate the guiding sleeve tilt angle in paralleling instruments, the diameter of guiding sleeves and drill shanks were measured for a number of instrument makes and Spirko type drill makes. Significant diameter differences between makes were found for drills as well as for sleeves. The guiding sleeve tilt angle changed considerably depending on drill—instrument combination. Selection of an unsuitably dimensioned drill could increase the sleeve tilt angle by about four times. A dimensional standardization of guiding shanks and sleeves is thus recommended.
In vitro plaque formation on dental amalgam
Authors: DUMMER P. M. H. , WILLS‐WOOD M.
Published: June 2007

A previously described method for the study of in vitro microbial plaque formation on dental materials has been utilized to assess microbial adhesion and growth on five commercially available dental amalgams.

Variations in both the amount and viability of the microbial plaques was found between the various types of amalgams.