bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparative study of three etching solutions
Authors: RETIEF D. H.
Published: June 2007

Conditioning of the enamel surface is an accepted procedure in several disciplines of dentistry to obtain increased bonding of dental materials to tooth surfaces. Three etching solutions commonly in use are 50% phosphoric acid, 50% phosphoric acid attenuated with 7% zinc oxide by weight and 50% citric acid. The effects of these solutions on the contact angle of an uncured epoxy resin on, and the bond strength of an epoxy resin formulation to polished enamel surfaces were investigated and compared with the results obtained on polished, unconditioned surfaces. In addition, the rates of etching of enamel surfaces by these acids were determined. The attenuated phosphoric acid produced the greatest reduction in contact angles and the most marked increase in bond strengths. 50% phosphoric acid etched the enamel surface to a greater extent than the other conditioning solutions.
Nocturnal electromyographic evaluation of bruxism patients undergoing short term splint therapy
Authors: SOLBERG WILLIAM K. , CLARK GLENN T. , RUGH JOHN D.
Published: June 2007

Eight confirmed bruxist subjects were investigated using portable electromyographic equipment. Nocturnal masseteric muscle activity, as measured by electromyography, was reduced immediately following the insertion of a full arch maxillary stabilization splint. It remained low until the splints were removed, at which time all but one subject's EMG values returned to pretreatment levels. Although the short term splint therapy did not show a permanent reduction in EMG levels, a dramatic reduction has been demonstrated during treatment.
Histological features of the palatal mucosa in denture sore mouth
Authors: VAN MENS P. R. , PINKSE‐VEEN M. J. , JAMES J.
Published: June 2007

A histological investigation was carried out on biopsy specimens taken from patients suffering from denture sore mouth. The results were compared with those obtained in previous investigations on denture and non‐denture‐wearers. The sections were studied by standardized quantitative morphometric methods. After 4 years the denture bearing palatal epithelium from both groups, the denture wearers and the patients suffering from a denture sore mouth did not show changes in mean thickness of the epithelium compared with the controls. The mitotic index in denture bearing epithelium from patients suffering from denture sore mouth was three times lower than in the epithelium of the normal denture wearers. The three groups of patients investigated did not show differences in density of mast cells in the lamina propria of their palatal epithelium.
The bonding of a polymeric fissure sealant to topical fluoride‐treated teeth
Authors: LOW T. , VON FRAUNHOFER J. A. , WINTER G. B.
Published: June 2007

The tensile bond strength of a polymeric fissure sealant to enamel treated with a variety of topical fluorides was determined. Application of acidulated phosphate fluoride solutions (APF) prior to and after acid etching reduces the tensile bond strength of Nuva Seal from 36·6±9·0 kg/cm2 to 4·9±3·3 kg/cm2 and 23·8±6·3 kg/cm3 respectively. The treatment of the etched enamel with freshly prepared 8% stannous fluoride solution prior to Nuva Seal® application significantly increases the tensile bond strength to 55·7±17·1 kg/cm2. It is recommended that clinical procedures such as the application of fissure sealants, acid etch composite restorations and the direct attachment of orthodontic brackets, all of which involve etching of the enamel, should not be preceeded by the topical application of APF solutions.
Electrochemical properties of copper and gold containing dental amalgams
Authors: SARKAR N. K. , GREENER E. H.
Published: June 2007

Alloying or admixing of a dental amalgam alloy with an element or alloy which has a higher affinity for tin offers a means for eliminating the corrosion prone γ2 phase. Accordingly, the corrosion behaviour of non‐conventional amalgams containing Cu and Au were investigated by anodic polarization studies in Ringer's solution. The Cu containing amalgams were produced by admixing Cu‐Hg (copper amalgam) with conventional amalgam in the ratios of 0.5:1 and 1:1. A 10 w/o Au in Ag3Sn was used as the gold amalgam alloy. The anodic polarization profile of the 0.5:1 Cu admixed was similar in shape to conventional amalgams although current densities were less. After ageing for I month the – 250 mV peak associated with γ2 disappeared and the current density decreased by ten fold. After 2 months the current density decreased by one hundred fold. The anodic polarization of the 1: 1 Cu admixed amalgams did not display the ‐250 mV (γ2) peak after 1 week and current densities were I03 below that of conventional amalgams. The behaviour of these interesting amalgams is rationalized on the basis of the ease of formation of Cu‐Sn intermetallics where Cu/Sn > 3. The anodic polarization profile of 10 w/o Au containing amalgam essentially is that of conventional amalgam and does not change drastically after 6 months. Although the Au may reduce or eliminate the γ2 phase the resulting AuSn4 apparently corrodes in an analogous fashion. However, since distribution of AuSn4 may be different from γ2, i.e. not continuous, the effect of corrosion on its mechanical properties may be different.
A study of the occurrence of symptons of disease of the temporomandibular joint masticatory musculature and related structures
Authors: HANSSON TORE , NILNER MARIA
Published: June 2007

An examination of the temporomandibular joints, masticatory musculature and related structures was made on 1069 persons working in a ship‐building yard in the south of Sweden. One‐fifth of the persons reported that they had frequent headache and one‐fourth of the persons reported TMJ‐sounds.

Clinical examination of the temporomandibular joints and masticatory musculature showed that clicking of the TMJ was the most common symptom (65%) followed by tenderness of the masticatory musculature to palpation (37%) and tenderness of the temporomandibular joint (10%). Thirty per cent of the persons examined reported two or more of these symptoms. Severe abrasion was noted in 12%.

The results of the investigation suggested that the frequency of diseases related to function of the masticatory system is high. It was estimated that some 25–30% of the persons examined were in need of treatment.
Tooth preparation for full coverage—basic principles and rationalized clinical procedures
Authors: STERN NOAH , GRAJOWER RAFAEL
Published: June 2007

The basic principles of tooth preparation for full coverage are discussed and an efficient method is described for the operative procedure. The purpose of each of the four stages in this technique and of the five different diamond instruments which are used in their performance, is discussed. Modifications of the procedure are given for posterior and anterior teeth as well as for teeth with periodontal involvement. Comparing the relative merit of different types of finishing lines, the chamfer type was found most suitable for the majority of preparations.
Some properties of dental ceramics
Authors: JONES DEREK W. , WILSON H. J.
Published: June 2007

The rather exacting aesthetic requirements of dental restorations has largely dictated the composition of dental ceramic materials. The so‐called dental porcelains have evolved from the traditional whiteware formula of feldspar, clay and quartz. One of the first variables which might be considered is that of chemical composition. It is, however, generally accepted that for ceramic materials small variations in composition are not critical. Since the early work of Watts in 1918, little interest has been expressed in the chemical composition of dental porcelain.

The composition of traditional dental porcelains has evolved over a period of many years by practical trial and error, as discussed by Jones (1971). The development of dental porcelains advanced to the point where any major improvements in physical properties could only be achieved by major changes in composition and technique as advocated by McLean & Hughes (1965). The resulting alumina/glass composites which have been developed use a technique which involves the build up of an inner core which contains a high proportion of crystalline alumina (45–50 %) embedded in a glass matrix surrounded by a transparent outer veneer.

This work compares the effect of such inter‐related variables as composition, inclusion of filler, viscosity, texture, hardness, and strength of the fired product.
A two‐year clinical study comparing the effect of dentifrices on selected dental materials
Authors: SCHIFF THOMAS , VOLPE ANTHONY R.
Published: June 2007

A two‐year double‐blind human clinical study has been conducted to determine the comparative effect of two commercially available dentifrices on selected dental materials.

Forty‐three adult subjects were selected to participate. They received either acrylic resin or silicate restorations in their anterior teeth, or a full cast gold veneer crown with an acrylic surface.

The subjects were randomly assigned to either one of the two dentifrices and utilized the dentifrice in their normal manner at least 3 times per day.

The dental restorations were clinically evaluated in reference to their surface characteristics immediately after placement, and after 3, 6, 12 and 24 months' use of the dentifrices. The acrylic surfaces of the veneer crowns were also evaluated at these same time periods; however, in this case an in vivo tooth surface reflectance measurement technique was also utilized.

The results of this clinical study provide the following conclusion after 24 months use of the two dentifrices: There was no difference between the two dentifrices in that neither dentifrice produced any abnormal or unusual effect on the surface characteristics of either the acrylic or silicate anterior restorations, or the acrylic surfaces of the veneer crowns.
Utilization of electrical conductivity as an alternative method of assessing marginal leakage of pit and fissure sealants
Authors: MARTINEZ C. R. , GREENER E. H.
Published: June 2007

The electrical conductivity readings of extracted human teeth were taken: prior to placement of pit and fissure sealants; immediately after placement of the pit and fissure sealants; 2 weeks after immersion of the specimens in distilled water at 37°C; and after 7200 strokes on a toothbrushing machine. The specimens were then immersed in dye for 24 h, sectioned and evaluated for evidence of dye penetration.

The electrical conductivity readings were then compared to dye penetration results to determine if a correlation existed.

A positive correlation existed between the electrical conductivity readings and dye penetration. Threshold values of electrical conductivity existed (which varied for each sealant)—readings above these threshold values indicated sealant failure or leakage.

The possibility of using electrical conductivity as a diagnostic tool is definitely worthy of further research—particularly its potential as an in vivo method of assessing leakage.
Lateral displacement of the mandible in Rhesus monkeys
Authors: BLANKENSHIP JOHN R. , RAMFJORD SIGURD P.
Published: June 2007

Lateral displacement of the mandible was induced experimentally in five adult male Rhesus monkeys. Following from 2½2 weeks to 19 months, the animals were sacrificed and examined histologically. Two of the monkeys received H3 proline 4 months prior to sacrifice and radioautographs were prepared. The lateral displacement apparently caused great discomfort because the monkeys refused to eat and lost weight rapidly for a few months. After about 12 months, the monkeys could again eat their normal diet to the extent they started to gain weight slowly.

The histological and radio‐autographic findings indicated almost no changes of the articular surfaces of the temporomandibular joints. However, extensive reorganization of the neck of the condyles was observed. Severe periodontal trauma and extensive movements of the teeth occurred in spite of the fact that the teeth in each jaw were splinted firmly together.
Quantitative changes in dental plaque formation related to removable partial dentures
Authors: EL GHAMRAWY ESSAM
Published: June 2007

Plaque formation on forty‐four teeth acting as abutments for removable partial dentures was studied while the patients were wearing their dentures and while they were not. The amount of plaque was assessed according to Quigley & Hein (1962), modified by Kardel & Bay (1967). In addition, that formed occlusally was evaluated by an occlusal plaque scoring index designed for the present study.

It was found that the wearing of partial dentures increased the formation of plaque on all tooth surfaces under investigation.
In vitro attachment of Streptococcus sanguis to dental crown and bridge cements
Authors: ØRSTAVIK DAG , ØRSTAVIK JON
Published: June 2007

The ability of a common dental plaque bacterium, Streptococcus sanguis, to adhere to dental crown and bridge cements in vitro was investigated. Cylindrical blocks of five different commercial brands of cement, with and without acquired pellicles, were incubated with buffer suspensions of S. sanguis for 1 h. Attached bacteria were counted under the microscope. S. sanguis had particularly high affinity for uncoated resin cement. In contrast, the carboxylate cement tested was a poor substrate for the adherence of this bacterium. The other cement types (zinc phosphate, zinc oxide and silico‐phosphate) had intermediary qualities as adhering surfaces.

The presence of an acquired pellicle, obtained by pretreatment with saliva, influenced the initial adherence of bacteria to cement in vitro. On the resin cement a salivary pellicle strongly suppressed the bacterial adhesion. For the zinc phosphate, zinc oxide and silico‐phosphate cements a pellicle slightly enhanced the attachment of S. sanguis. On the carboxylate cement only few organisms attached also after pretreatment with saliva.
Linear dimensional changes during setting of two polycarboxylate cements
Authors: ØILO GUDBRAND
Published: June 2007

The linear dimensional changes of two polycarboxylate cements have been studied. The measurements were performed on specimens placed on a mercury bath, and were started 3 min after commencing the mix. The specimens were allowed to set at 37°C under various environmental humidity.

Specimens from one of the polycarboxylate cements (Durelon®), were made using both the universal liquid and the thin liquid meant for cementation. The powder/ liquid ratios (P/L) were either 2.5 or 1.5.

Specimens from the second cement (Poly‐C®), were made using the liquid meant for cementation only with a P/L of 1.5.

The dimensional changes of Durelon were dependent on the powder/liquid ratio and the environmental humidity during setting. Under dry conditions this cement showed a maximum contraction of 4.60% after 14 days when a high P/L was used and 6.10% when a low P/L was used. After 1 day under wet conditions no significant differences between cements with high and low P/L were registered, and the mean contraction was 1.10%.

The dimensional changes of Poly‐C were dependent on the environmental humidity, and after 14 days under dry conditions a maximum contraction of 5.50% was registered and after 1 day under wet conditions a contraction of 0.60%.

The contraction of the polycarboxylate cements tested in this study started earlier and were in general more pronounced than that observed for a zinc phosphate cement (Øilo, 1975).
Periodontal conditions in patients 5 years following insertion of fixed prostheses
Authors: VALDERHAUGW J. , BIRKELAND J.M.
Published: June 2007

The oral hygiene, gingival condition, pocket depth and loss of attachment were studied during a period of 5 years in a group of patients (114) who had been treated with fixed dental protheses. Eighty‐four per cent of the subjects had received periodontal therapy prior to the prosthetic treatment. During the study the subjects participated in an oral hygiene programme.

Crown margins were located sub‐gingivally, at the gingiva, and supra‐gingivally. Initially 65% of the crown margins were sub‐gingival compared to 41% 5 years later. When the crown margins were located sub‐gingivally there was an increase in Gingival Index scores 2 and 3, in pocket depth, and in loss of attachment compared to a supra‐gingival placement. However, most of the alterations were small.
The use of root abutments in the support of complete dentures
Authors: RALPH J. P. , MURRAY F. D.
Published: June 2007

A clinical study of the use of root abutments as an aid to the support of complete dentures is presented. This technique offers a realistic alternative for patients who are reluctant to face the loss of their remaining natural teeth and the wearing of complete dentures. The abutments enhance the support and stability of the dentures and appear to slow the rate of alveolar resorption. The clinical procedures are straightforward and can be readily applied in general dental practice.
The effect of anodic polarization on the tensile strength of dental amalgam
Authors: WANG CHEN C. P. , GREENER E. H.
Published: June 2007

The effect of corrosion upon dental amalgam was studied by measuring the effect of anodic polarization on its tensile strength. A conventional tensile testing method using dumb‐bell shaped specimens deformed along the long axis was employed. The results showed a significant reduction (27%) in the mean tensile strength, due to the anodic polarization of conventional amalgam, whereas the strength of the high Cu‐containing Dispersalloy amalgam was unaffected by polarization. When the diametral tensile strengths of polarized and unpolarized conventional amalgam and Dispersalloy specimens were compared (ADA Specification No. 1), no significant difference in strength was observed.

These results indicate that the anodic corrosion of γ2 phase network in the conventional amalgam fillings can be directly attributed to a reduction of tensile strength which would be manifested clinically as marginal breakdown. It appears also that the diametral tensile test is not sufficiently discriminating to allow for an in vitro simulation of clinical properties.
Cytotoxicity of temporary crown and bridge materials
Authors: DAHL BJøRN L. , øRSTAVIK JON
Published: June 2007

In vitro cytotoxicity of freshly prepared temporary crown and bridge materials was studied using mouse fibroblasts prelabelled with 3H‐thymidine grown in shake flask cultures. Cytotoxicity was measured as (1) lack of cell multiplication, (2) stainability with Trypan blue and (3) release of 3H‐labelled material to the culture medium. All the materials tested (zinc oxide‐eugenol cement (ZOE), Scutan® and Sevriton®) were cytotoxic in this system, ZOE most strongly. This finding favours the view that the in vitro cytotoxicity of dental materials should not be used alone as a screening test for their biological compatibility under clinical conditions since clinical experience and previous in vivo findings have established that ZOE is biologically well tolerated by the dental tissues.
The effect of the bite plane splint on the electromyographic silent period duration
Authors: BEEMSTERBOER P. L. , McNAMARA D. C. , HOLDEN S. , ASH M. M.
Published: June 2007

An electromyographic study of the masseter and anterior part of the temporalis muscles was performed on ten patients presenting temporomandibular joint dysfunction symptoms. The EMG silent periods (SP) produced in the open‐close‐clench cycle and jaw‐jerk reflex were compared for duration before and after treatment with an occlusal bite splint. Following use of the splint, there was a shortening of SP indicating the possible use of the duration of SP as a diagnostic measurement, and also as an indication of treatment effectiveness.
Microstructural changes of dental amalgam by copper additions
Authors: MARSHALL G. W. , FINKELSTEIN G. F. , MARSHALL S. J. , GREENER E. H.
Published: June 2007

The γ2 (Sn7–8Hg) phase of the amalgam structure has been established as the most corrosion prone of conventional dental amalgam. Cu rich amalgams are currently of interest because some formulations appear to reduce or eliminate the γ2 phase. This investigation compares the microstructures of conventional amalgam to Cu rich amalgams prepared by various methods, i.e. a commercial alloy (Dispersalloy), an admixture of Cu amalgam with conventional amalgam, and admixtures of 30% Cu‐Ag‐Sn ternary alloy with conventional amalgam.

These variations in amalgam formulation resulted in marked reduction or elimination of the γ2 phase in the Cu rich amalgam microstructures. The matrix or γ1 (Ag2Hg3) phase was common to all formulations. Other phases and their proportions changed dramatically with different methods of introducing the Cu.

The saline corrosion resistance, determined by potentiostatic anodic polarization in Ringer's solution, was enhanced for the Cu rich amalgams as a result of the elimination of the γ2 phase. This study suggests there are a variety of methods to introduce copper into amalgams and that these methods generally serve to eliminate γ2 phase and increase saline corrosion resistance.
A galvanic study of different amalgams
Authors: CHEN C. P. WANG , GREENER E. H.
Published: June 2007

Due to the difference in open circuit potential (OCP) versus SCE for Aristaloy* amalgam (‐969 mV) and Dispersalloy† amalgam (‐549 mV) in Ringer's solution at 25°C, a galvanic cell was created with Dispersalloy amalgam as cathode and Aristaloy amalgam as anode.

The galvanic corrosion current was studied as a function of time for the above cell as well as for a cell of type III dental gold‡ (OCP is +0·5 mV) versus Aristaloy amalgam. The initial corrosion current of the latter cell (105 μA) is about twice that for the cell of aristaloy amalgam versus Dispersalloy amalgam (54 μA), however, their passivating behaviour is quite similar.

Also, an interrupted galvanic corrosion test simulating the oral ‘make and break’ situation was performed. A much higher corrosion current than the steady state was found when the two electrodes resumed contact.
Reconstruction of alveolar ridge and jaw defects resulting from gunshot wounds
Authors: SANDERS BRUCE
Published: June 2007

Reconstruction and rehabilitation of acquired defects of the oral cavity is an important dental service. Severe deformities of the jaws may result secondary to gunshot wounds of the oral‐facial region. New advaces in soft and hard tissue surgical reconstruction can be of great benefit to the patient when coupled with prosthetic rehabilitation.

In recent years there has been a significant increase in the incidence of gunshot wounds in the civilian population in the United States, and those of the mouth and jaws are relatively common‐place.

Gunshot wounds to the face and jaws may cause gross destruction of tissues. Although immediate definitive treatment of wounds reduces the mutilating effect, a significant number of patients require extensive reconstructive procedures. In addition, prosthetic rehabilitation is almost always needed.

The purpose of this paper is to briefly review some recent advances in reconstruction of the maxilla and mandible following gunshot injuries.
An application of potentiostatic current ‐time transients to study the corrosion of dental amalgams*
Authors: SARKAR N.K. , GREENER E. H.
Published: June 2007

Potentiostatic current‐time transients obtained during anodic polarization of a conventional dental amalgam and its component phases have been analysed to characterize the possibel electrochemical reactions involved in amalgam corrosion. These reactions involve such surface phenomena as adsorption, anodic film formation, film dissolution, etc. which are well reflected in current time transients. The analysis of these transients from the standpoint of thermodynamics, suggests that the saline corrosion of dental amalgam may occur through the dissolution of the passive anodic films on Sn7Hg (γ2) and Cu6Sn5 (η′) and the dissolution reaction appears to be the formation of tin‐oxychloride.
Bruxism and its effect on the teeth
Authors: XHONGA FRIDA A.
Published: June 2007

This study presents the progress of tooth wear and the change in structural morphology on individual teeth of bruxist subjects, compared with non‐bruxers. From the results of this investigation it can be concluded that the tooth wear progressed faster in bruxers than in non‐bruxers. Scanning electron microscope investigations revealed in 10 teeth the same pattern of deep grooves and striations on the wear‐facets of active bruxers.
Aspects of functional improvement after treatment of a pain dysfunction patient
Authors: HONÉE G. L. J. M. , DE VRIES J. H.
Published: June 2007

First results of an investigation of several aspects of the function of the chewing apparatus by means of optical‐electric movement scanning, EMG and occlusal sound registration on one time base, are presented. Observations made on a patient with pain‐dysfunction syndrome before and after treatment has been compared with observations made on a healthy subject. It has been suggested that the method used, may be of value for objective evaluation of functional improvement and analyses of several aspects of the physiology of the chewing apparatus.
Assessment of the quality of restorations
Authors: ELDERTON R. J.
Published: June 2007

Most assessments of the quality of restorations are entirely subjective and involve standard clinical diagnostic equipment. However in recent years there has been an increasing demand for more accurate and reliable methods. Attempts to achieve these have been directed mainly towards the standardization of clinical judgements by the provision of various systems of guidelines of criteria upon which to base them. While these have improved the usefulness of the assessments, they have remained largely subjective. Furthermore, the efficacy of using the particular criteria selected are themselves open to questioning.

By the use of more complex methods of examination, often in the field of restorative materials research, assessments have been made of various features of restorations and a body of knowledge concerning factors that might influence or manifest their quality has been built up. However the true significance of much of this knowledge in terms of the clinical behaviour, and thus the finite quality of restorations in service, has yet to be established, for many of the studies have been undertaken in isolation from the dynamic conditions of function in the mouth. Notably, however, a few objective clinical studies have been carried out and objective measurements of some factors affecting the quality of restorations have been reported.
Kinematics of the tooth tapping movement
Authors: WIDMALM SEVEN‐ERIK , HEDEGÅD BJÖRN
Published: June 2007

Electrical activity in the masseter muscles and tooth contact vibrations were recorded simultaneously from subjects tapping their teeth slowly into maximal intercuspidation and again with maximal frequency. High speed cinephotography was also used with four of the ten subjects.

Three main parts could be distinguished on the obtained graphical representation of the tooth tapping movement: tooth contact phase (TCP), opening phase (OP) and closing phase (CP).

Tapping frequency was increased by decreasing the jaw opening degree and the durations of TCP, OP and CP. The jaw velocity immediately before tooth contact, which may be of significance for the reflex response, was however not increased. The average jaw speed was nevertheless increased from 10 to 15 cm/s since the turning from OP to CP was more abrupt in high than in low frequency tapping.

The duration of electrical activity after tooth contact was significantly shorter at tapping with high than with low frequency. The teeth maintained contact without detectable rebound between each open‐close cycle. The OP started about 100 ms after the cessation of electrical activity both at low and high tapping freqency. The time between end of electrical activity and the start of a new OP was supposed to be dependent upon the relaxation time of the masseter muscles.
An objective method for measuring the surface morphology of cavities and restorations in vivo
Authors: ELDERTON R. J.
Published: June 2007

A method was developed for quantifying morphological characteristics of cavities and restored teeth, in a quest for more knowledge of factors which determine the long term clinical success or failure of restorations, and which may therefore be used in making objective assessments of their quality. The method involved obtaining sequential silicone rubber replicas of teeth in vivo, sectioning them in planned planes, and then making objective linear and angular measurements directly from × 10 photographs of the resulting profiles and from positive models. It would seem that the method could be applied in a variety of clinical investigations.
In vitro polarization of dental amalgam in human saliva
Authors: FINKELSTEIN G. F. , GREENER E. H.
Published: June 2007

Potentiostatic anodic polarization techniques in Ringer's solution are commonly used for the evaluation of the corrosion resistance of dental amalgam. This in vitro method strives to simulate the in vivo electrochemical behaviour of amalgam in an electrolyte of natural saliva.

Several types of dental amalgam were anodically polarized in natural saliva solutions and supernatant saliva solutions. The anodic polarization profiles are presented, as well as scanning electron micrographs and X‐ray analysis of the corroded amalgam surfaces. These reveal corrosion products consistent with results found with previous artificial salivas as well as deposits possibly related to the organic component of natural saliva.
The surface structure of the human mandibular condyle in health and disease
Authors: JAGGER R. G. , WHITTAKER D. K.
Published: June 2007

Surface features of the human mandibular condyle have been studied by scanning and electron microscopy. Normal condyles possessed features similar to those in other diarthrodial joints but with certain differences. Two types of erosion and an exostosis were seen in diseased joints and the surface structure is described.
Horizontal stabilization of upper and lower borders of the comfortable zone
Authors: TRYDE GERD , STOLTZE K. , BRILL N.
Published: June 2007

Using a screw jack device the upper and lower borders of the comfortable zone were recorded in a two step procedure designed to counteract bias inherent in previous measurements. In these measurements, successively increasing and decreasing values of zonal borders were recorded corresponding to a fully closed or fully opened starting position of the screw. Both of these positions are outside the comfortable zone. The two step procedure used a starting position which was supposed to lie inside the comfortable zone. However, the procedure did not achieve its aim fully. It succeeded only in stabilizing the lower border values. In the discussion hypothetical considerations are made concerning theneurophysiological mechanism underlying recordings of the borders of the comfortable zone, which might explain the differential behaviour of the zonal borders.
In vitro studies of fluoridated amalgam
Authors: HURST P.S. , von FRAUNHOFER J.A.
Published: June 2007

Four types of fluoridated amalgam were assessed in vitro in terms of fluoride release, corrosion behaviour and compressive strength, and compared with amalgams prepared from the corresponding non‐fluoridated alloys. Although corrosion susceptibility was found to be increased, steady release of the fluoride ion was demonstrated over a 16‐week period, indicating that fluoridated amalgams might be prophylactically employed in clinical dentistry as a means of overcoming the problem of secondary caries associated with amalgam restorations.
Does a temperature gradient exist across the mucogingival junction?
Authors: BRILL N. , MAEDA T. , STOLTZE K.
Published: June 2007

On the assumption that the colour difference between attached gingiva and alveolar mucosa is accompanied by a temperature difference, twenty subjects with a high standard of oral health were studied. Five points on either side of the mucogingival junction were examined by means of a thermocouple probe. A mean difference amounting to about 2/3°C was found between the surface temperatures of the two structures.
Tissue hypersensitivity to dental materials
Authors: DAHL B. L.
Published: June 2007

Five cases of tissue hypersensitivity to Scutan and two to Impregum are reported. The reaction to Scutan was a burning sensation in the mucosa in contact with the material, followed by swelling and erythematous ulcers producing heavy discomfort. All symptoms gradually disappeared after removal of the material. To Impregum the reaction was basically the same, only less vigorous since contact with the material is of limited duration. All the cases were women in the menopause. Attention is drawn to the possibility of hormonal imbalance being a factor of importance in the development of hypersensitivity reactions to materials of this sort.
Viscoelastic properties of elastomeric impression materials: polysulphide, silicone and polyether rubbers
Authors: TOLLEY L. G. , CRAIG R. G.
Published: June 2007

Creep compliance measurements were shown to be effective in characterizing the elastic, retarded elastic, and viscous properties of polysulphide, silicone, and polyether impression materials. The test is particularly valuable in that the creep compliance was independent of load, allowing the mechanical properties to be represented by a single total creep compliance curve which can be used to determine the various creep components. The total recovered compliance was shown to be independent of time provided the polymerization had progressed sufficiently before testing was done. The retarded elastic and viscous compliances contributed proportionally to the total creep compliance and thus did not affect the rankings of materials. The viscous compliance of polysulphide A decreased enough after 1 h so that the creep compliance of A and D were not different. The creep compliance measurements showed that the polysulphide materials were the most viscoelastic followed by silicone and polyether impression materials. The polyether was the most nearly ideal elastic material but it had a flexibility comparable to heavy body polysulphide. Of particular interest was the observation that polyether with thinner in ratios up to 1 : 1 by length had no practical effect on the viscoelastic properties.
Ultra‐violet absorption by two ultra‐violet activated sealantss
Authors: YOUNG K. C. , MAIN C. , GILLESPIE F. C. , STEPHEN K. W.
Published: June 2007

Since the ability of u.v. setting pit and fissure sealants to set in depth is dependent on the penetration of the u.v. radiation, the absorption coefficients of Nuva‐seal and Alphaseal were determined at 365 nm, the wavelength of radiation used to polymerise both materials. Nuva‐seal and Alphaseal had absorption coefficients of 0·165 mm −1 and 6·25 mm −1, respectively. The u.v. fluorescent dye present in Alphaseal contributed 2·5 mm −1 to its absorption coefficient and the remaining absorption was due to the 5% w/w catalyst concentration present, since the basic resin had no significant absorption. Therefore Nuva‐seal may set adequately to the depths required of fissure sealants, but Alphaseal may not, unless a very high intensity u.v. source is used. A reduction in the catalyst concentration and the removal of the u.v. fluorescent dye might improve the setting characteristics of Alphaseal.
The effect of finishing on the anodic polarization of high‐copper amalgams
Authors: BOYER DANIEL B. , CHAN KAI CHIU , SVARE CARL W. , BRAMSON JAMES B.
Published: June 2007

The influence of surface finishing procedures on the corrodibility of high‐copper amalgams was measured. Anodic polarization curves were determined in Ringer's solution for amalgam samples made from a dispersion and a ternary alloy. Three types of finishes were compared: as carved, burnished, and polished.

The polarization curves of the burnished and polished specimens were statistically similar (P > 0·05) at all potentials investigated. The carved samples exhibited higher corrosion currents at most of the potentials investigated.
Size of variables in mandibular movements in autopsy material
Authors: RASMUSSEN OLE COLLIN
Published: June 2007

Autopsy was performed on the right temporomandibular joint in eleven individuals with a mean age of 71 years. Standard positions indicative for protrusion, laterotrusive border movement and posterior opening movement were photographed in the sagittal plane. Size of movements of the disc and condylar head were recorded, as well as movements of a reference point in the mental region. The slope of the anterior discal movement was estimated and mandibular rotation during posterior opening was registered. Centre of rotation during the hinge movement was in all cases located to the craniodorsal part of the condylar head. Attempt to construct centres of rotation in the eminence and condylar head for the horizontal movements was in vain. The discussion deals with the influence of the specific kind of material on the results and the possible systematic differences to clinical material.
Split cast discrepancies and arbitrary axis dental cast articulator mounting
Authors: LAING D.P. , WISE M.D.
Published: June 2007

Ths split cast technique has been advocated as a useful clinical tool for checking the reproducibility of jaw registrations. As originally described it requires the use of a kinematic face bow. Since the arbitrary axis used with the Whip‐Mix face bow has been demonstrated to be close to that of the kinematic axis, it is feasible that the split cast technique could be used with such a face bow. Casts of ten subjects were mounted with retruded jaw registrations, made at different degrees of vertical separation. The upper casts were mounted using both kinematic and arbitrary face bow transfers, and the accuracy of mating of the split components measured.

With the arbitrary face bow, the components of the split cast system only mated when repeated registrations were of exactly the same thickness, i.e. the same vertical dimension. Small differences in vertical dimensions produced the largest errors at the split. Any slight variations in the thickness of the retruded registrations will therefore invalidate the use of the split cast method in conjunction with an arbitrary face bow.

The importance of the correct spatial relationship of mounted dental casts for the adequate diagnosis and treatment of a variety of oral and associated masticatory system disturbances is well documented (Lucia, 1961; Lucia, 1964; Celenza, 1973). However, accurate execution of the clinical and laboratory stages is necessary if the required information is to be obtained from articulated casts.
The cavity sealing ability of composite restorations subjected to thermal stress
Authors: KIDD EDWINA A. M. , HARRINGTON E. , GRIEVE A.R.
Published: June 2007

An artificial caries technique, using a diffusion controlled acidified gel, was used to create in vitro artificial lesions adjacent to composite restorations. Prior to gel immersion, test specimens were temperature‐cycled in a machine designed specifically for this purpose. Examination of control specimens showed little evidence of leakage, the presence of a cavity wall lesion being used as an indication of leakage. Compared to the controls, the test specimens showed either a reduction or no change in leakage pattern. It is suggested that thermal percolation may not be of clinical significance in relation to composite restorations.
The adaptation of composite materials to etched enamel surfaces
Authors: LOW T. , LEEand K.W. , VON FRAUNHOFER J. A.
Published: June 2007

The adaptation of three composite materials and one unfilled bis‐GMA resin to etched enamel surfaces was investigated by examining under optical and scanning electron microscopy the adhesive‐enamel junction of replicas. The length of the tags and the density of tagging observed on the replicas showed that the three composite materials, Adaptic, Concise and Delphic, adapted to the etched enamel surface equally as well as the unfilled resin Nuva Seal. The results of this study together with available results of mechanical testing and clinical studies allow the conclusion that the successful retention of the composite filling materials to an etched enamel surface is not dependent on the use of an intermediate unfilled resin or bonding agent.
Tissue conditioners as functional impression materials
Authors: MCCARTHY J.A. , MOSER J.B.
Published: June 2007

The adaptation of three composite materials and one unfilled bis‐GMA resin to etched enamel surfaces was investigated by examining under optical and scanning electron microscopy the adhesive‐enamel junction of replicas. The length of the tags and the density of tagging observed on the replicas showed that the three composite materials, Adaptic, Concise and Delphic, adapted to the etched enamel surface equally as well as the unfilled resin Nuva Seal. The results of this study together with available results of mechanical testing and clinical studies allow the conclusion that the successful retention of the composite filling materials to an etched enamel surface is not dependent on the use of an intermediate unfilled resin or bonding agent.
The convergence angle in teeth prepared for artificial crowns
Authors: OHM E. , SILNESS J.
Published: June 2007

The bucco‐lingual and mesio‐distal convergence angles in vital and rootfilled teeth prepared for complete crowns were measured microscopically on 190 stone dies. In vital teeth the mean convergence angles varied between approximately 19 and 27 degrees. In rootfilled teeth the mean angles varied between 12 and 37.
A methodological study of errors in vertical measurements of edentulous ridge height on orthopantomographic radiograms
Authors: RAMSTAD TORE , HENSTEN‐PETTERSEN ODD , MOHN ERIK , IBRAHIM SAMIRA I.
Published: June 2007

The purpose of this methodological investigation was to study the relative magnitude of the various errors in vertical ridge measurements from orthopantomograms of edentulous patients.

The study was divided into two parts, Part I and Part II. Part I included eleven patients. Two standard orthopantomograms were taken of each patient. Part II included five of the eleven patients in Part I. Here, a third X‐ray taken with the mouth open was added to the X‐rays from Part I. The X‐rays were traced by three dentists.

Twelve vertical measurements in the maxilla and in the mandible were made. The variance produced by the patients (morphological variance) and those produced by the dentist, the X‐ray, the interaction patient‐dentist, the interaction dentist‐X‐ray and the random variance (methodological variances) were separately estimated on the basis of a three‐way mixed analysis of variance model.

In Part I, on the average, the sum of the methodological variances constituted 1·7 % and 2·5 % of the total variance in the maxilla and in the mandible respectively. The X‐ray produced the greatest single variance component, averaging 1·1 % in both jaws. Although generally statistically significant, the remaining methodological variances were of low magnitude. The interaction patient‐dentist, however, was not significant in most cases.

In Part II, on the average, the sum of the methodological variances increased to 38·8 % in the maxilla and 4·6 % in the mandible, mainly caused by an increase in the variance produced by the X‐ray.
Creep, corrosion and marginal fracture of dental amalgams
Authors: SARKAR N. K.
Published: June 2007

An analysis of the available information on creep and corrosion of dental amalgams is presented in an attempt to understand their role in the marginal breakdown of amalgam restorations.
Reproducibility of the normalized electromyographic recordings of the masseter muscle by using the EMG recording during maximal clenching as a standard
Authors: HOSMAN H. , NAEIJE M.
Published: June 2007

A method of normalizing the integrated EMG recordings from the masseter muscles is introduced. For each subject investigated the maximal clenching force is remarkably constant and reproducible. This makes it possible to normalize the integrated EMG recordings to the EMG activity at the maximal clenching force without having to measure this force at the beginning of every experiment. These normalized integrated EMG activities give a good quantitative impression of the static force exerted by the masseter muscle, and therefore can be compared quantitatively over several experiments. The relationship between the normalized integrated EMG activities and the clenching force is linear up to approximately 80% of the maximal clenching force.
The effect of placement of cervical margins of class II amalgam restorations on plaque accumulation and gingival health
Authors: GULLO C.A.O. , POWELL R.N.
Published: June 2007

The effects of restoring early proximal carious lesions were investigated in a series of thirty‐six surfaces. In eighteen lesions the cervical margins of the restorations extended subgingivally, and in eighteen the margins were located supragingivally. Three months after restoration, plaque accumulation was not significantly different from pre‐restoration levels. The degree of gingival inflammation showed a significant improvement after restoration where cervical margins were finished supragingivally (P < 0.5). Where margins were finished subgingivally a highly significant deterioration in gingival health occurred (P < 0.1).
Offsetting the increased plaque formation in partial denture wearers by tooth brushing
Authors: EL GHAMRAWY ESSAM , RUNOV J.
Published: June 2007

In two experiments, each running for 2 weeks, plaque formation was studied on forty‐two teeth acting as abutments for removable partial dentures. In the first experiment, only ordinary tooth brushing was practised. Plaque accumulation was rapid, yielding scores ranging between 2 and 5. In the second experiment, following instruction in intensive tooth brushing, plaque scores were depressed to approximately 1.5 and below.
Plaque accumulation following the wearing of different types of removable partial dentures
Authors: ADDY M. , BATES J.F.
Published: June 2007

A group of forty‐five patients took part in a study to assess the effects of wearing partial dentures upon the accumulation of plaque in the mouth in the absence of oral hygiene. The wearing of a partial denture resulted in a significant increase in plaque accumulation and this increase was the result of a significant increase in both buccal and lingual plaque. Furthermore in a group of ten patients a small, but significant, increase in plaque occurred in the opposing arch during the wearing of the dentures. The accumulation of plaque on the buccal aspect of the teeth appeared unrelated to the type of denture worn. However, significantly more plaque accumulated on the lingual aspect of all the teeth in those patients wearing lower plate dentures as opposed to lower bar dentures. In the 3 day study periods only a small increase in plaque occurred on the palatal aspect of the upper anterior teeth not covered by any part of the partial denture and no significant increase occurred on the lingual aspect of the lower anterior teeth not covered by the partial denture. A highly significant increase occurred on the lingual aspect of lower anterior teeth covered by the lingual plate of the partial denture. Overall the wearing of a denture day and night resulted in more plaque accumulation compared with day only wearing of dentures. However considering the denture types this significant increase was not apparent in the lower plate dentures. The results provide further evidence of the potentially adverse effect partial dentures may have upon the supporting structures of the teeth when oral hygiene procedures carried out by the patient are inadequate.