Transverse and bond strength of restorative resins.
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Composite Resins↗
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Results for “DENTAL RESTORATION, PERMANENT”
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The wettability of composite resinous filling materials.
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Adhesiveness↗
Flow and creep of dental amalgam.
The intention of the study was to assess the differences in results obtained from creep and flow measurements of dental amalgams. Flow registers deformation during setting. Creep denotes the deformation of the set amalgam. The present study did not demonstrate a correlation between flow and creep, and creep is considered a more desirable parameter to include in a standard.
Dental Amalgam↗
Contraction stresses of composite resin filling materials.
The polymerization shrinkage of composite resin filling materials and the tensile stresses developed when the shrinkage is restrained were measured in an in vitro experiment. This allows an estimation to be made of the forces exerted upon the enamel walls of cavities filled with the resin in the acid etch technique. The results indicate that the stresses acting on the enamel are low compared to the tensile strength of the enamel.
Composite Resins↗
Marginal leakage in occlusally loaded, etched, class-II composite resin restorations.
Microleakage was studied in class-II cavities restored with a calcium hydroxide liner and an adhesive system combined with two different posterior composite resins. The restorations were exposed to repeated loading when immersed in dye solution. The teeth were cut, and microleakage along the cavity walls and into dentin was evaluated by light microscopy. Dye penetration at the interface between the cavity and the restoration was recorded in 61% of the loaded and in 30% of the unloaded teeth. The difference between loaded and unloaded was greater for the teeth lined with Life than with Gluma dentin bonding.
Acid Etching, Dental↗
Cusp fracture of endodontically treated posterior teeth restored with amalgam. Teeth restored in Denmark before 1975 versus after 1979.
The aim of the present study was to analyze the frequency and the severity of cuspal fracture for posterior teeth endodontically treated by 91 Danish dentists and restored with amalgam either before 1975 or after 1979. A database from a previous study was analyzed (1584 teeth with an MO, a DO, or an MOD amalgam restoration without cuspal overlays). Teeth restored before 1975 had a significantly lower frequency of cusp fracture than teeth restored after 1979. Moreover, when comparing the frequency of subcrestal fractures, that of the second group (after 1979) was more than twice as high as that of the first group (before 1975). Two factors with a bearing on these findings changed in the time period 1975-1979; the high-copper amalgams took over in Denmark, and the use of Gates-Glidden burs to achieve straight-line access to the root canal was introduced. It is suggested that the weakening of the coronal part of the root, caused by the use of Gates-Glidden burs, and the expansion and low creep of high-copper amalgams may be two of the reasons for the increased frequency and severity of cuspal fracture found in the past decade in Denmark.
Bicuspid↗
The teaching of all-ceramic restorations in Scandinavian dental schools: a survey.
The study was designed to survey the curricular requirements, types of clinical experience, and materials/ techniques used in teaching programs for all-ceramic restorations in Scandinavian dental schools. All 13 dental schools responded. Ten offered some clinical experience to pre-doctoral students, but only one required one all-ceramic restoration. The departments of fixed prosthodontics had the main teaching responsibility. All-ceramic crowns were taught at 9, veneers at 7, and inlays/onlays at 10 dental schools. A wide range of different teaching concepts, materials, and views on indications and contraindications was reported. It appears as if all-ceramic restorations are regarded as experimental by the teaching institutions, although the dental industry and some practitioners strongly recommend these types of restorations.
Ceramics↗
Selection of restorative materials in general dental practice in Sweden.
The aim of this study was to record any differences in the selection of materials in private dental practices in Sweden during 1993-95, after a ban on amalgam had been proposed by politicians, compared with those obtained in a similar survey in 1978-79. A total of 177 clinicians participated in the present survey, which recorded the total number of restorations they placed and the number of composite, amalgam, and glass ionomers inserted in the treatment of primary caries and for replacement of restorations. Furthermore, the number of intact amalgam restorations replaced by composite and the number and types of inlays and laminates cemented were accounted for. Marked changes in the selection of direct restorative materials were noted in the present study compared with the survey in 1978-79. Resin-based composite materials are taking over the routine posterior restorative material, also in stress-bearing areas. Glass ionomer restorative materials are used preferentially in the treatment of primary caries. The use of amalgam restorations has decreased in relative and absolute numbers. Inlays are infrequently used but, when used, usually include three or more surfaces, and ceramic materials predominate.
Attitude of Health Personnel↗
Subjective aspects of patients with traumatized teeth. A 15-year follow-up study.
The aim of this study was to obtain detailed information about adults who suffered trauma to the teeth as children. A total of 102 patients took part. The patients answered a questionnaire and were interviewed before the oral examination. Thirty-nine per cent of the patients reported dissatisfaction either with the color and/or anatomic form of the traumatized teeth or reconstruction. Most of the individuals did not remember having received any information about prognosis for the traumatized teeth. Twenty-one per cent of the patients remembered pain during treatment, and 25% remembered only the behavior and attitudes of the dental team. It can be concluded that all dental treatment in children with traumatized teeth must be carried out as painlessly as possible, and the dental team should minimize discomfort during the treatment. Good knowledge about traumatology and management can reduce stress and anxiety for both the patient and the dental team.
Adolescent↗
Polymerization shrinkage and contraction force of composite resin restorative inserted with "Megafiller".
This study quantified the contraction force and polymerization shrinkage of composite resins with/without beta-Quartz Glass Ceramic Inserts (BQCI) as "Megafiller". The materials used for the determination included a chemically cured composite and five light-cured composites. The system for measuring contraction force consisted of a transparent teflon tube for preparing the specimen, a small load cell, a dynamic strain gauge and a pen-recorder. After the composite was packed into the teflon mold, a BQCI (Type R3) was inserted through the opening and the specimen was cured. Linear polymerization shrinkage of the composites was measured every 10 seconds from the start of mixing or irradiation to 90 minutes by the mercury bath method. Three pieces each of BQCI (Type T3) were inserted in each specimen. The results suggested that BQCI was markedly effective in reducing polymerization shrinkage, but was not always effective in reducing the contraction force during polymerization.
Acrylic Resins↗
Effects of dietary acids on surface microhardness of various tooth-colored restoratives.
The aim of this in vitro study was to investigate if surface microhardness of Fuji IX GP, Vitremer, Dyract AP, and Prodigy is influenced by conditioning in aqueous solutions of lactic, orthophosphoric, citric, and acetic acids against bidistilled water (which was used as control). The pH values of acids used in this study were representative of dietary acids. All specimens were stored in bidistilled water for one week and then conditioned in the respective test solutions for another week. Citric (p<0.05) and acetic acids reduced, while lactic and orthophosphoric acids (p<0.05) increased the microhardness of both Fuji IX GP and Vitremer. On the other hand, microhardness of both Dyract AP and Prodigy was significantly reduced by all acidic media (p<0.05). The observed differences in the surface microhardness of various tooth-colored restorative materials conditioned in several media varied not only with the pH but also the nature of the acidic solution, and with the composition of the evaluated material.
Acetic Acid↗
Effects of heat treatments and Sn, Ga and In additives on mechanical properties of 35Ag-30Pd-20Au-15Cu alloy.
The mechanical properties of six 35Ag-30Pd-20Au-15Cu alloys containing different contents (2% and 4%) of Sn, Ga, or In and a 35Ag-30Pd-20Au-15Cu alloy without additives were evaluated. These alloys were subjected to four different heat treatments before a mechanical test. The distribution of the elements and their contents were analyzed. The mechanical properties of 35Ag-30Pd-20Au-15Cu alloy changed in wide-ranging ways with different heat treatments and with different additive contents. The effects of heat treatment on tensile strength and hardness significantly varied with different additives and their contents. These different changes could be attributed to the formation of different phases in these alloys. Based on the high strength and wide-ranging changes in the mechanical properties when subjected to softening and hardening heat treatments, the 2% Sn-added, 2% In-added, and 4% Ga-added alloys can be recommended for different dental restorations such as crown & bridges, inlays, and denture frameworks.
Analysis of Variance↗
Enamel micro-cracks produced around restorations with flowable composites.
In this study, enamel micro-cracks produced around flowable composite restorations were observed using a stereomicroscope and a scanning confocal laser microscope (SCLM). The effects of polymerization shrinkage, mobility of composite and polishing period after filling on the incidence of marginal enamel micro-cracks were examined. Enamel micro-cracks were observed on all of the composite restorations when the restoration was polished immediately after filling. Enamel micro-cracks distributed approximately parallel to the cavity margin and located 0.01-0.3 mm from the restored cavity margin. The occurrence of enamel micro-cracks was higher in conventional hybrid composite restorations than in flowable composites, and when polished 15 minutes after filling (as compared to 24 hours after filling).
Analysis of Variance↗
Color change of newly developed esthetic restorative material immersed in food-simulating solutions.
Recently, an esthetic tooth coating material has been developed. The material consisted of a primer solution, a base coat, and a top coat. The purpose of this study, therefore, was to evaluate the color change of this tooth coating material and two resin composites after immersion in food-simulating, staining solutions. To this end, the newly developed coating material with and without its top coat, a flowable resin composite, and a hybrid resin composite were employed for the evaluation. The specimens were subjected to an experimental 24-hour staining cycle: 7-hour immersion in coffee, green tea or red wine, then 17-hour immersion in artificial saliva solution containing 0.3% mucin. After 24 hours, 3 days, 1, 2, and 4 weeks of immersion, the color changes of all specimen surfaces were measured. Compared with the other materials, the deltaE* value of coating material without its top coat tended to increase as the immersion period increased until 4 weeks. On the other hand, the deltaE* value of coating material with its top coat measured the lowest among the materials tested. Based on the results obtained, it was concluded that when using this recently developed tooth coating material in dental clinics, its top coat should be properly applied.
Coated Materials, Biocompatible↗
A new method for the evaluation of the wear of restorative materials on Class V cavity.
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Composite Resins↗
Effect of enamel preparations on fracture resistance of composite resin buildup of fractures involving dentine in anterior bovine teeth: an in vitro study.
Sixty bovine teeth with simulated mesio-incisal angle fracture were randomly and equally divided in one untreated (control) group and three experimental groups (Bevel, Chamfer and newly introduced Stair-step Chamfer preparation group) to evaluate the effect of enamel preparations on the fracture resistance of composite resin. Post restoration, fracture mechanics approach was used to quantify the failure of composite resins in testing the samples in Instron testing machine. Mean peak failure load (Newton) of composite amongst experimental groups was observed in the order; Chamfer (326.09 +/- 72.73), Stair-step chamfer (315.21 +/- 81.77) and Bevel (253.83 +/- 67.38). Results of the One-Way ANOVA revealed significant difference in the mean peak failure load values of the four different groups. (P<0.001) Scheffe's Post-Hoc comparison test (Subset for alpha = 0.05) revealed that there was no significant difference in the mean peak failure load values of the bevel, stair-step chamfer and chamfer preparation when considered together, but the mean peak values of control group (605.22 +/- 48.96) were observed significantly higher. Failure mode evaluation revealed, majority of failures occurred as cohesive and mixed type for all the experimental groups. Adhesive type failure was observed maximum (33%) in the bevel group. Stair-step chamfer preparation showed greatest potential for application and use as it no only demonstrated comparable values to Chamfer preparation ['t' value (0.39) (P > 0.05)] but also involved sacrificing less amount of tooth structure adjacent to fractured edge.
Animals↗
[Fatigue properties of restorative dental materials].
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Composite Resins↗
Effect of intracanal restorative material on the stiffness of endodontically treated teeth.
This study compared the ability of various intracanal restorative materials to restore the stiffness of endodontically treated teeth. We randomly placed bovine central incisors into six groups. We did not instrument negative control teeth, and we instrumented, but did not restore, positive control teeth. We restored teeth in the experimental groups with resin-based composite, resin-based composite plus a fiberglass post, or resin-based composite plus a cemented metal post. We subjected all teeth to nondestructive, compressive testing and recorded the stiffness of each sample. Results indicated that performing endodontic access and instrumentation alone resulted in a 24% loss in tooth stiffness. Teeth restored using an intracanal resin bonding technique alone or in combination with a post regained the stiffness lost from access and instrumentation, and teeth that were restored with bonded resin and a metal post cemented with Panavia 21 cement were significantly stiffer than the untreated negative control group (p < 0.05). Our results suggest that intracanal resin bonding techniques may reduce the need for immediate crown placement after endodontic therapy.
Animals↗