bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colour measurements of all ceramic crown systems
Authors: ROSENSTIEL S. F. , PORTER S. S. , JOHNSTON W. M. 
Published: June 2007

SummaryThe objectives of this study were: (i) to determine variability among colour parameters of five different ceramic crown systems; and (ii) to measure the effect of using coloured luting agents on restoration colour. The crown systems studied were Cerestore, Dicor, Hi‐Ceram, Renaissance, and Vitadur‐N. Five crowns for each system were made according to manufacturer's instructions with the same nominal shade (Vita LuminVacuum A2) to fit an Ivorine central incisor tooth. Restoration thickness was adjusted to within ±0.1mm (±0.05mm in the mid‐facial area where colour measurements were to be made) with the aid of a dial calliper prior to glazing or, in the case of Dicor, surface staining. Where a core was part of the system this was fabricated to the minimum recommended thickness. The crowns were cemented using luting agents of five different colours in a randomly chosen sequence. The colour of each restoration/cement combination was measured three times using a small‐area colorimeter (Minolta CR‐121). The variance of each colour parameter (L*,a*,b*) was statistically compared for each crown system using an analysis of variance procedure, as was the effect of the cement. Observed differences were related to visual perception by using the colour difference formula. There were statistically significant differences among the variances of the crown systems and the cements, with significant interactions between crown systems and direction of colour and between‐ cement and direction of colour. Restorations made with different ceramic crown systems had noticeably different colour despite having the same nominal shade. Changing the shade of the luting agent had a perceivable effect on Dicor crowns and, to a lesser extent, on Vitadur‐N crowns but not on the other systems due, presumably, to the opacity of their core materials.
Clinical performance of resin‐bonded bridges: a 5‐year prospective study. II. The influence of patient‐dependent variables
Authors: CREUGERS N. H. J. , SNOEK P. A. , VAN'T HOF M. A. , KÄYSER A. F. 
Published: June 2007

SummaryA total of 203 resin‐bonded bridges was inserted under controlled clinical conditions and evaluated for a number of patient‐dependent variables over a period of 5 years. Of the variables evaluated only ‘initial occlusion of the abutment teeth’ and ‘location in the dental arch’ had a significant influence on the retention of resin‐bonded bridges. Anterior resin‐bonded bridges were more durable than posterior bridges. Mandibular posterior bridges showed the lowest retention ratio. It is concluded that the design of posterior resin‐bonded bridges should include tooth preparation or a wrap‐around design of the retainers.
Comments on standardization of reflex measurements in human masseter muscle, including silent periods
Authors: VAN DER GLAS H. W. , VAN STEENBERGHE D. 
Published: June 2007

SummaryThe following comments are given on the guidelines suggested by Türker (1988) for studies on oral reflexes using the surface EMG of the masseter muscles in man, including the silent period.(i) Attention should not be confined to electrical stimulation since mechanoreceptors in the periodontium, especially in the periodontal ligament, can only be activated by mechanical stimulation of a tooth. Furthermore, different modes of stimulation and stimulation sites do not yield equivalent reflex complexes. Weak and transient mechanical stimulation of a tooth while clenching at a low level of 5 or 10% MVC is a selective model (89%) to study the influence of periodontal receptors.(ii) Statistical criteria should be applied on rectified and averaged EMG records to prevent any subjective bias in the measurements of reflex variables. Whether a period of increased EMG activity is due to clustering of action protentials of motor units firing of which was delayed by a preceding inhibition, or to a real excitatory influence, can be assessed by applying statistical criteria on averaged and subsequently rectified records.(iii) The clenching level should be less than 25% of MVC to avoid muscle fatigue, and to elicit pronounced reflexes with a weak and therefore more selective stimulus.(iv) The stimulus intensity should be much less than six times the threshold if selectivity for mechanoreceptors is desired. Furthermore, periods of increased activity in surface EMG resulting from a weak stimulus are probably due to real excitatory influences and not to clustering of motor unit action potentials after an inhibition.(v) Jaw separation and the use of a force transducer are not always advantageous. If mechanical stimulation is applied to a tooth, clenching in full habitual occlusion causes a complete suppression of the influence of muscle spindles. A shift in activity between the various elevator muscles, and hence a change in activity of the muscle studied, may occur during an experimental session if biting force is used as a feedback. Such a shift is not relevant if feedback is carried out on rectified and lowpass filtered (1.6 Hz) EMG of the muscle studied.
Correlation between clinical and histological evaluations of the peri‐implant gingiva around the single‐crystal sapphire endosseous implant
Authors: AKAGAWA YASUMASA , TAKATA TAKASHI , MATSUMOTO TOSHIKADO , NIKAI HIROMASA , TSURU HIROMICHI 
Published: June 2007

SummaryThe correlation between clinical periodontal parameters and histological structure of the gingiva around a single‐crystal sapphire implant has been evaluated in two volunteer subjects. The implants had functioned after 6 years as the distal abutment of implant bridges in the Kennedy class II mandible. First, clinical evaluation was performed (gingival bleeding index, crevicular fluid volume, plaque index and probing depth) of the gingiva around the implant and natural teeth abutments and then a small piece of peri‐implant gingiva was excised from the lingual site of the implant of each subject for histological evaluation. The clinical evaluation using the periodontal parameter indices corresponded with the histological evaluation of the peri‐implant gingiva. The result suggests that it is possible for such parameters to be used in practice for judging the success of an implant.
Conditioning of root canals prior to dowel cementation with composite luting cement and two dentine adhesive systems
Authors: LIBERMAN R. , BEN‐AMAR A. , URSTEIN M. , GONTAR G. , FITZIG S. 
Published: June 2007

SummaryTwo hundred and forty root canals of extracted single‐rooted teeth were prepared to the same dimension, and Dentatus posts of equal size were cemented without screwing them into the dentine. Five cleansing solutions and two dentine adhesive systems were evaluated prior to post‐cementation using chemical‐cure composite resin.‘Pull‐out' tests were then conducted in order to evaluate the bond strength of these intra‐pulpal posts. The use of Conclude (composite luting cement) alone, with or without the cleansing solutions, resulted in significantly lower pull‐out forces. Scotchbond Dental Adhesive gave significantly better results, regardless of the cleansing solution used. Gluma Dentine Adhesive significantly increased the pullout forces only when used with its supplied cleanser or Tubulicid.
The radiopacity of glass ionomer dental materials
Authors: WILLIAMS J.A. , BILLINGTON R.W. 
Published: June 2007

SummaryAlthough some glass ionomer dental materials are described as radiopaque by the manufacturer, it is rare for the actual degree of radiopacity to be specified. Using a technique previously described for measurement of the radiopacity of enamel, dentine and composite resin dental materials, the radiopacity of a number of glass ionomer materials, including restorative, lining and luting cements, was determined.
The influence of spacers on forces exerted on the abutment teeth of complete mandibular overdentures
Authors: OGATA K. , AOKI T. 
Published: June 2007

SummaryThe avoidance of lateral forces on overdenture retainers is essential to prevent pathological change in the supporting tissues of the root abutment. In this study, the influence of spacer thickness on the vertical and lateral forces exerted on overdenture abutments was examined clinically.Two subjects with an edentulous maxilla, two canines and a left first premolar remaining in the mandible were selected for the experiment. The anchor type attachment was embedded in the left canine portion of the denture base. The transducer used for the previous study (Ogata et al., 1990), was embedded in this left canine portion. The transducer could detect the magnitude and direction of lateral forces exerted on an abutment tooth parallel to the Camper's plane. The other transducer was embedded in the left first mandibular premolar area, and could detect vertical forces exerted on the abutment tooth perpendicular to the Camper's plane. Furthermore, the transducer could change the space between a denture base and an abutment tooth to 1.5 mm, 0.6 mm or 0.3 mm. Therefore measurements could be made in the same way as if three experimental dentures had been used with a different thickness spacer. Recordings of forces were taken during food chewing, using each spacer on the day of denture insertion and twice at intervals of 1–2 weeks thereafter.The results demonstrated that as spacer thickness decreased, the magnitude of the lateral forces decreased, while the magnitude of the vertical forces increased. These findings suggest that a large part of the lateral component of forces exerted on an abutment tooth could be converted into a vertical component by using a thinner spacer.
Assessment of adverse reactions to prosthodontic materials
Authors: DAHL B. L. , HENSTEN‐PETTERSEN A. , LYBERG T. 
Published: June 2007

SummaryIn 1978 five cases of so‐called hypersensitivity reactions to Scutan® and two to Impregum® were reported (Dahl, 1978). The aim of the present study was to assess whether hypersensitivity or cell‐mediated immune reactions were associated with the adverse clinical reactions in these patients or in others who had experienced the same reactions. Epicutaneous patch testing and lymphocyte transformation tests were carried out in a total of 13 individuals. The findings were difficult to interpret, because there was no consistent association between skin reactions and cell‐mediated immune responses in subjects with suspected allergies. Other possible reasons for the reactions originally recorded were therefore discussed. It was concluded that adverse reactions associated with immune‐mediated, delayed type hypersensitivity reactions may be elicited by prosthodontic materials, but other pathogenic mechanisms and aetiological factors responsible for the reactions observed should also be considered.
The unreliability of facial measurements in the determination of the vertical dimension of occlusion in edentulous patients
Authors: CAROSSA S. , CATAPANO S. , SCOTTI R. , PRETI G. 
Published: June 2007

SummaryThe aim of this research was to test the reliability of skin markers in the determination of the V.D.O. in edentulous patients during prosthetic rehabilitation. Two resin baseplates were constructed; on the upper one a modified pin of the Central Bearing Point registration device was fixed with impression compound. The height of the pin could be altered by rotating the pin directly in the patient's mouth with a probe. Two lead spheres were inserted on the resin base‐plate as bone markers, and two others were fixed to the skin as markers, one above (end of nose) and one below (point of chin) the oral commissure. Five lateral cephalometric radiographs were exposed for each patient, raising the V.D.O. by 1.2 mm on each occasion. Statistical analysis of measurements made on the resulting radiographs showed a very strong correlation between bone markers and pin position, whereas great variation and considerable differences were found between skin markers and bone as well as measurements.
An investigation into the microhardness of a light cured composite when cured through varying thicknesses of porcelain
Authors: WARREN K. 
Published: June 2007

SummaryAn investigation was carried out to measure the completeness of cure of samples of a composite resin, light cured for 40s and 60s through porcelain discs of varying thickness. Once cured, each specimen was subjected to Vickers microhardness testing to assess the completeness of cure. Composite resin specimens cured without an intervening porcelain disc were used to establish a baseline. The results showed that increasing the thickness of the porcelain disc produced a statistically significant decrease in microhardness of the composite resin. Increasing the cure time from 40s to 60s produced a significant increase in microhardness. The increase in microhardness with increased cure time was more pronounced when the discs of thickness 1 mm and 2 mm were used, and when there was no overlying porcelain disc.
A clinical evaluation of conventional bridgework
Authors: CHEUNG G.S.P. , DIMMER A. , MELLOR R. , GALE M. 
Published: June 2007

SummaryThe present study evaluated the incidence and causes of failure of conventional bridgework provided in the Prince Philip Dental Hospital, Hong Kong. Any bridge that utilized resin‐bonded (Maryland) retainers was excluded from this study. All patients with bridges fitted between 1981 and 1987 were recalled for review, and 143 patients attended, a response rate of 77%. A total of 169 bridges were examined, their mean length of service being 35 months. Thirty‐five bridges were deemed to have failed. The most frequent cause was endodontic, followed by loss of retention, then persistent pain and sensitivity. Failures of endodontic origin affected mostly anterior bridges, which could be attributed to the over‐sized pulp of anterior teeth and the amount of tooth reduction required for the ceramometal retainer. All of the bridges that failed because of endodontic problems had had ceramometal retainers. Taking posterior bridges alone, the failure rate was 4.4% per year. From the evidence of this study, the replacement of the maxillary canine with a cantilever bridge appears to be contra‐indicated.
Wear of teeth in a mentally retarded population
Authors: ØILO G. , HATLE G. , GAD A‐L. , NIOM B.L. DAHL 
Published: June 2007

SummaryThe study includes an evaluation of dental wear in 69 individuals, 44 men and 25 women, of mean age 35 years and range 18–59 years, living in a home for mentally retarded persons. Wear was evaluated with a newly developed index based on Ryges' system, where the need for treatment is the key issue. The index consisted of three categories representing clinical situations from no wear to moderate, age dependent wear without problems for the patient, and two categories in which treatment was found to be necessary either to prevent future problems or to improve the present situation.A relatively large number of teeth showed considerable wear in the 20–29 year age group. Wear was observed predominantly in incisors and canines. Only 1 % of cases were considered to require treatment. Wear increased with age, and more than 5% of teeth were diagnosed as needing treatment in the 30–39 year and 40–49 year age groups.Wear in the studied population was found to be more severe than that observed in an urban population from the same area in a parallel study.
Clinical performance of resin‐bonded bridges: a 5‐year prospective study. Part III: failure characteristics and survival after rebonding
Authors: CREUGERS N.H.J. , SNOEK P.A. , VAN'T HOF M.A. , KÄUYSER A.F. 
Published: June 2007

SummaryA total of 203 resin‐bonded bridges were inserted under controlled clinical conditions and evaluated over a period of 5 years. During the evaluation period there were 47 dislodgements and 30 pontic fractures. The majority of the failures were retreated successfully. Dislodgement was in most cases due to fracture at the resin/retainer interface. The small number of fractures at the resin/tooth interface indicate that the clinical procedures, as used in this study, were satisfactory. Dislodged and rebonded resin‐bonded bridges had a lower retention than original bonded bridges, indicating that patients with a dislodged bridge are a risk group for the retention of rebonded bridges. However, possible factors that may be responsible for this higher risk could not be demonstrated. The bridges which were removed for repair of the pontics and rebonded showed an acceptable retention. There was no relationship between the failure characteristic and the retainer type or the cementation material used.
Nocturnal bruxing events in healthy geriatric subjects
Authors: OKESON J.P. , PHILLIPS B.A. , BERRY D.T.R. , COOK Y. , PAESANI D. , GALANTE J. 
Published: June 2007

SummaryThirty healthy geriatric subjects were studied during a single night of sleep in a sleep laboratory. Unilateral masseter muscle activity was recorded in addition to the standard polysomnographic study. The geriatric subjects in this study exhibited fewer bruxing events than other subjects reported in the literature. Certain conditions that have not been previously investigated, such as sleep position, type of bruxing event, and relationship to the state of the dentition, are reported.
Current views on biological testing of restorative materials*
Authors: NIOM I. A. MJÖR 
Published: June 2007

SummaryIt is anticipated that biological testing in Europe after 1 January 1993 will be based on European Standards (EN) common to all biomaterials. No details regarding the future certification programmes are yet available. In vitro cytotoxicity, tissue reactions to implanted materials and pulp studies (‘usage tests’) represent three levels commonly used for biological testing of restorative dental materials. Considerable variation in test methodology exists, and no universal agreement prevails with regard to which test or tests are most appropriate for evaluation of the biological effects of restorative materials. The latter also include a number of allergens, but few biological side‐effects have been noted in clinical practice.
Dental materials science — the maintenance of standards
Authors: TYAS M. J. 
Published: June 2007

SummaryStandards for dental materials are available for both biological and chemical/physical properties. In order to predict the clinical performance of a material by means of standard tests, both the test and the method used in the test should ideally simulate clinical usage. However, owing to lack of knowledge with regard to intra‐oral failure modes, and technical considerations in the performance of tests, this ideal may not always be achieved.
Postural contractile activities of human jaw muscles following use of an occlusal splint
Authors: CARR A.B. , CHRISTENSEN L.V. , DONEGAN S.J. , ZIEBERT G.J. 
Published: June 2007

SummaryAs induced by an occlusal splint over a period of 1 week, this study monitored surface electromyographic changes in the postural contractile activities of jaw elevator and depressor muscles in six healthy adults. The immediate effect of the occlusal splint was to increase the postural contractile activities of the suprahyoid muscles. All postural muscle activities showed wide‐ranging biological variation, but the activities induced by the splint tended to stabilize within 1 week, with decreased postural activities in the masseter and anterior temporalis muscles, and increased postural activities in the suprahyoid muscles.
Porosity of pit and fissure sealants
Authors: LEKKA M. , PAPAGIANNOULIS L. , ELIADES G. 
Published: June 2007

SummaryThe aim of this study was to investigate the bulk porosity of a range of pit and fissure sealants. The following materials were included in the study: Concise White Sealant and Delton (chemically cured); Delton (visible light‐cured); Helioseal, Visioseal and Prolite (visible light‐cured with delivery from the bottle via cannule): Delton, Luma Seal and Prisma Shield (visible light‐cured with syringe‐type direct delivery systems). Five cylindrical samples, 7 mm in diameter and 1 mm in thickness, were prepared from each sealant and the following parameters were analysed in a computer‐controlled mercury porosimeter: (i) total cumulative pore volume; (ii) specific surface area of pores; (iii) percentage total porosity (iv) bulk density; and (v) pore radius distribution. According to the results, the chemically cured sealants exhibited total cumulative pore volume, specific surface area of pores and total porosity. Significant differences were detected within the group of visible light‐cured materials. The visible light‐cured sealants with syringe‐type delivery exhibited the lowest porosity.
Wedges in restorative dentistry: principles and applications
Authors: ELI I. , WEISS E. , KOZLOVSKY A. , LEVI N. 
Published: June 2007

SummaryOverhanging margins of proximal restorations are a well‐known, iatrogenic cause of periodontal pathology. The high incidence of such findings in Western societies should arouse the concern of the dental community. However, overhanging margins represent only part of the iatrogenic problem created by the misuse of wedges in restorative procedures. Other causes include incorrect proximal contouring, inadequate contact points and under‐ or overfilling the restorative material.The understanding of the variables associated with wedge selection and positioning has a major role to play in the prevention of iatrogenic periodontal pathology associated with restorative procedures. It is concluded that:(i) the occlusion of the matrix band to the remaining healthy tooth structure of the gingival cavosurface line angle should be achieved solely by the correct application of the wedges;(ii) the effect of the wedges on the proximal contour and contact area should be carefully re‐evaluated prior to insertion of the restorative material;(iii) various sizes and shapes of wedges and a sharp knife for carving must be readily available.
Chewing and swallowing activity of masticatory muscles in patients with a complete upper and a partial lower denture
Authors: TALLGREN A. , TRYDE G. 
Published: June 2007

SummaryThe chewing and swallowing activity of jaw‐closing muscles was studies longitudinally in 30 partially edentulous subjects who were provided with an immediate complete upper and a partial lower denture. Electromyographic recordings of the anterior temporal and masseter muscles were obtained during habitual chewing of apple and during swallowing of saliva and water, before final extractions and 7 weeks, 6 months, 1 year and 2 years after denture insertion.At the pre‐treatment stage, when the patients were chewing with a residual anterior dentition, the mean voltages showed low values compared to findings reported in subjects with a complete natural dentition. After 6 months of denture use, the chewing forces showed significant increases in amplitude, and the increased force of contraction persisted to the 2‐year stage.The recordings of swallowing revealed no significant changes in maximal mean voltage during the observation period. However, there was a significant increase in the duration of the swallows after 1 year of denture wearing, which might be related to stabilization of the complete upper denture due to continuing resorption of the maxillary ridge.