American Dental Association Specification Research Articles

Physical and chemical properties of a new root-end filling material

This study determined the chemical composition, pH, and radiopacity of mineral trioxide aggregate (MTA), and also compared the setting time, compressive strength, and solubility of this material with those of amalgam, Super-EBA, and Intermediate Restorative Material (IRM). X-ray energy dispersive spectrometer in conjunction with the scanning electron microscope were used to determine the composition of MTA, and the pH value of MTA was assessed with a pH meter using a temperature-compensated electrode. The radiopacity of MTA was determined according to the method described by the International Organization for Standardization. The setting time and compressive strength of these materials were determined according to methods recommended by the British Standards Institution. The degree of solubility of the materials was assessed according to modified American Dental Association specifications. The results showed that the main molecules present in MTA are calcium and phosphorous ions. In addition, MTA has a pH of 10.2 initially, which rises to 12.5 three hours after mixing. MTA is more radiopaque than Super-EBA and IRM. Amalgam had the shortest setting time (4 min) and MTA the longest (2 h 45 min). At 24 h MTA had the lowest compressive strength (40 MPa) among the materials, but it increased after 21 days to 67 MPa. Finally, except for IRM, none of the materials tested showed any solubility under the conditions of this study.

Proportioning effect on physical and chemical properties of polysulfide impression material

This study investigated the effect of variation in proportioning polysulfide base and catalyst. Light, regular, and heavy-bodied pastes were mixed in linear equivalents of base-to-catalyst proportions of 30 70 , 40 60 , 50 50 , 60 40 , and 70 30 . Compression set, strain in compression, and consistency tests conformed to the American Dental Association (ADA) Specification 19 guidelines. The amount of solvent-leachable components and differences in the cross-linked nature of the cured products were studied. Compression set and strain in compression tests met the ADA specification guidelines. Some consistency values fell outside of the ADA specification limits. The leachable content increased with increasing proportions of catalyst, but polymer cross-linking was remarkably similar for all bodied materials tested. Clinicians need not fear a significant property alteration in polysulfide impression material by the differences (within ±20% of the manufacturer's suggested lengths) in proportioning the component pastes with “eyeball” estimation as directed in the instructions.

Sorption and solubility of 12 soft denture liners

The long-term stability of a soft denture liner depends to a large extent on the sorption and solubility of the liner. Because sorption and solubility are accompanied by a volumetric change, bacterial infestation, hardening, and color change, it is a physical property of importance. The purpose of this investigation was to determine the sorption and solubility of 12 soft denture liners (Verno-Soft, Super Soft, ProTech, Soft-Pak, Flexor, Novus, Molloplast-B, Durosoft, Justi Soft, Velvesoft, VinaSoft and Prolastic). They include nine copolymers, two silicones and one polyphosphazene fluoroelastomer. The sorption and solubility test was performed as outlined in American Dental Association (ADA) specification 12 for denture base polymers. Five specimens of each material were tested and data were collected at 1 week, 1 month, 3 months, 6 months, and 1 year. Sorption data varied from 0.2 to 5.6 mg/cm 2 at 1 week; 0.3 to 12.5 mg/cm 2 at 1 month; 0.1 to 22.0 mg/cm 2 at 3 months; 0,1 to 13.6 mg/cm 2 at 6 months; and 0.1 to 35.7 mg/cm 2 at 12 months. Solubility data varied from 0,0 to 0.4 mg/cm 2 at 1 week; 0.1 to 0.8 mg/cm 2 at 1 month; +0.1 to 1.2 mg/cm 2 at 3 months; 0.0 to 1.9 mg/cm 2 at 6 months; and +0.2 to 2.3 mg/cm 2 at 1 year. A statistical analysis of the data by two-way ANOVA and calculated Tukey intervals showed significant differences between materials at all time intervals. The results of this study have clinical implications because the sorption and solubility may affect the long-term life expectancy of the soft denture liner.

Effects of creep value and occlusal force on marginal adaptation of amalgam filling.

Creep of amalgam is thought to be a factor determining poor marginal adaptation. Clarification of the relationship between creep of amalgam in the cavity and creep value (American Dental Association specification no. 1; ADA #1) is essential to an understanding of the mechanism of marginal fracture and service life. However, only elastic stress analyses of amalgam in a cavity have been reported in the dental field. Therefore, the creep of amalgam in a class I cavity was simulated by an axisymmetric elastic creep finite-element method. The stress and time dependencies of the creep rate of amalgam were incorporated into this calculation. Creep values of 1.0 and 3.0% (ADA #1) were selected as amalgam properties. When the occlusal force on the amalgam filling was assumed in the vertical direction along the axis of the tooth, the rate of extrusion and rate of opening of the gap at the cavity margin were revealed by the simulation. The computed results show that the gap and extrusion were developed in direct proportion of the creep value and proportionally with the square of the occlusal force. Simulated results are in agreement with clinical findings of the service lives of restorations, i.e., a poor adaptation to the margin can be seen for 4-to-10-year-old amalgam fillings.

Luting cement-metal surface physicochemical interactions on film thickness

Low film thickness is critical to the clinical success of cemented castings. This study investigated the effect of luting agent-metal physico-chemical surface interactions on film thicknesses of representative luting agents. Control group luting agents were placed between two glass plates, as described by American Dental Association specifications 8, 61, and 66, and test group luting agents were positioned between glass and metal plates. The materials selected were zinc phosphate cement, polycar☐ylate cement, glass ionomer cement, glass ionomercomposite resin hybrid cement and a resinous cement, with a type III gold alloy, a noble metal ceramic alloy, and a base metal ceramic alloy. A two-way analysis of variance and follow-up tests were done. The effects of the type of metal surface, type of cement, and their statistical interaction significantly affected film thickness ( p < 0.0001). The type of cement had a greater affect on film thickness than the type of metal. A glass ionomer cement produced lower overall film thicknesses than other cement types, and a noble metal ceramic alloy created lower overall film thicknesses than other types of metal. American Dental Association specifications for cement film thickness did not accurately reflect normal cement use.

The use of microwave energy to cure denture acrylic resins

Experiments have been carried out on the curing of poly(methyl methacrylate) denture base material in a microwave oven, using conventional dental flasks and flask clamps. It has been shown that it is important (a) to maintain sufficient pressure on the materials, (b) to avoid gaseous porosity by not heating too rapidly initially, and (c) to ensure that all metal is protected from exposure to microwaves. When the appropriate conditions of polymerisation were used, microwave-cured samples had satisfactory physical and mechanical properties according to American Dental Association specification number 12.

Mechanical properties of heat-treated composite resin restorative materials

Clinical methods for heat treating composite resin restorations have been developed. In this investigation, the effect of heat treatments on the diametral tensile strength of composite resin was determined. The composite resin restorative materials were selected according to the manufacturers' suggested use for anterior or posterior teeth, filler particle composition, and light-cured or chemical polymerization. Samples were prepared according to American Dental Association specification No. 27, and heat treatments were accomplished with a Coltene DI 500 oven for curing at approximately 120 ° C for 7 minutes. Heat treatment substantially increased the diametral tensile strength tested, with the exception of the anterior hybrid particle ( p < 0.05). Composite resins with fine-particle inorganic fillers were significantly stronger than hybrid and microfilled composite resins.

Retentive strength, disintegration, and marginal quality of luting cements

This study evaluated the retention of complete crowns by using five different methods of cementation. Complete crowns were prepared with standardized dimensions on extracted human molars. Metal crowns were cast with a high noble gold ceramic alloy and were cemented with zinc phosphate cement, glass ionomer cement, composite resin cement, composite resin cement with a dentinal bonding agent, and adhesive resin cement. The retention was measured by subjecting the specimens to tensile load until fracture occurred. The disintegration was measured according to American Dental Association Specification No. 8, and the condition of the cements at the margins of crowns was analyzed by use of a scanning electron microscope. Kruskal-Wallis one-way analysis of variance revealed statistically significant differences between the mean retentive strengths. The retention of the zinc phosphate and the glass ionomer groups was significantly different from that of the adhesive resin group. The retention of the adhesive resin cement was 65% greater than the retention of the composite resin and the composite resin/dentinal bonding agent group, but the Mann-Whitney Wilcoxon rank sum test did not depict this difference as significant. The mean ± SD of the disintegration for the zinc phosphate, the glass ionomer cement, and the composite resin cement was 0.025 ± 0.013, 0.023 ± 0.011, and 0.017 ± 0.001, respectively. The scanning electron microscope analysis of the margins revealed that the composite resin cement was almost intact, the zinc phosphate was subjected to limited disintegration, and the glass ionomer displayed the worst marginal integrity.

Computer Simulation on Creep of Amalgam in Class I Cavity

The creep behavior of amalgam in Class I cavity was simulated by an axi-symmetric elastic creep finite element method. In this procedure, the stress and time dependencies of the creep strain of amalgam were incorporated. Exponents of stress and time dependencies were postulated as 2.0 and 1.0, respectively. Amalgam with 1.0% of creep value (tested by American Dental Association Specification No. 1) were selected for the material to calculate. Simulation was conducted for the occlusal force of 40, 100, and 150 N, respectively, on the caps of enamel and vertical direction to the axis of the tooth. Results show that creep strain of amalgam in the cavity did not increase linearly with time because the amalgam deformed to become stress-free and creep rate was a function of the stress. It was concluded that elastic deformation of the crown with no filling material in its cavity is an important factor in determining the creep strain and the gap between the cavity and the restorative material.

Creative ceramic color: A practical system

The main objective of the present in vitro study is to evaluate the antimicrobial activity and properties of irreversible hydrocolloid impression material incorporated with silver nanoparticles of varying size at different concentrations.Silver nanoparticles of 80–100, 50–80, 30–50 and 10–20 nm size were added to irreversible hydrocolloid impression material at 0.5, 1.0, 2.0 and 5.0 wt%. Antimicrobial activity of the silver nanoparticle incorporated irreversible hydrocolloid was measured using disk diffusion method. The gel strength, flow, gelation time and permanent deformation were measured according to American Dental Association specification #18. Data were analyzed using analysis of variation at a confidence interval of 95% (α = 0.05).Silver nanoparticles of 80–100 nm size have imparted superior antimicrobial activity to the irreversible hydrocolloid in a dose-dependent manner whereas finer nanoparticle size did not exhibit any antimicrobial activity. The addition of silver nanoparticles did not alter the properties of irreversible hydrocolloid at 0.5 and 1.0 wt% whereas at higher concentrations significant differences in flow, gelation time and strength were observed.The results of the present study indicate that silver nanoparticles of size range 80–100 nm are superior in imparting antimicrobial activity to irreversible hydrocolloid compared to finer particle size range.

The effect of immersion disinfection of elastomeric impressions on the surface detail reproduction of improved gypsum casts

This investigation examined improved gypsum casts for surface roughness and line-detail reproduction after the immersion disinfection of elastomeric impression materials in an acid glutaraldehyde, an alkaline glutaraldehyde, and a phenol. Impressions were made of a surface roughness standard (R a = 3.08 μm) that was custom made to include engraved grooves following American Dental Association specification No. 19. Mean surface roughness (R a) values for all casts of all combinations of disinfectant treatments, impression materials, and improved gypsum stones were obtained with a surface analyzer. Untreated impressions served as controls. Data examined by an analysis of variance indicated that the addition silicone and polyether impression materials provided a surface roughness similar to the precision displacement specimen standard. The acid glutaraldehyde disinfectant demonstrated enhanced line-detail reproduction compared with the standard. Addition silicone and polyether impression materials combined with the acid glutaraldehyde provided the model system closest to the mean surface roughness of the reference standard. These combinations revealed differences in the surface roughness reproduction among the represented improved dental stones.

An evaluation of the film thickness of resin luting agents

Acid-etched cast metal resin-bonded retainers require resin luting agents with film thicknesses similar to dental cements to allow complete seating of frameworks without the need for post-bonding adjustments. Conventional cements, restorative resins, and resin cements were compared in terms of film thickness by using the American Dental Association Specification No. 8 for zinc phosphate cement. Most of the resin luting agents had film thicknesses of 20 to 40 microns. Working time was seen to affect film thickness. The particle size of one resin was also examined under scanning electron micrograph.

Comparison of bending and tension tests for orthodontic wires

Stainless steel, cobalt-chromium-nickel (Elgiloy), nitinol, and beta titanium wires with diameters from 0.010 to 0.040 inch and in rectangular sizes from 0.017 × 0.025 to 0.019 × 0.025 inch were evaluated with the American Dental Association specification no. 32 bending test and the conventional tension test. The modulus of elasticity (E) and yield strength (YS) obtained with the two mechanical testing procedures are reported for as-received wires and after heat treatment at 900° F for the stainless steel and selected Elgiloy wires. Measured values of E and YS in bending were almost invariably higher than the corresponding values obtained in tension. The only general agreement between the modulus of elasticity in bending and tension was for the 0.040-inch diameter stainless steel wires. Anomalously high values of E in bending were also found for most of the heat-treated stainless steel and Elgiloy groups. Difficulties with the bending test are attributed to loading effects at both ends of the test span and deviation of the bent specimen from a circular arc. Improved procedures are described for performing the tension test on the relatively small cross-section orthodontic wires.

A scanning electron microscope study of dentinal tubule continuity in monkey tooth sections.

Abstract The American Dental Association (ADA) and Federation Dentaire Internationale (FDI) specifications for the biological evaluation of dental materials in experimental Cavities in dentine require that sections permit dentinal tubules to be followed from cavity floor to pulp lumen. The aim of this study was to investigate this requirement in the specification. Twenty hematoxylin and eosin stained sections of vervet monkey incisor teeth satisfying the ADA and FDI specifications were selected. Adjacent unstained sections of the same specimens were prepared for scanning electron microscopy, and a low power photomicrograph was taken of the dentine between the cavity floor and pulp for each specimen. Two areas on each photomicrograph were selected using a superimposed grid and random number table and this area was re‐photographed at higher magnification on the specimen. A histometric analysis of the 40 SEM photomicrographs thus prepared showed that the dentinal tubules in 14 specimens were cut in cross‐section, 14 were tangential and only 12 were longitudinal sections. None of die tubules examined in the high power photomicrographs was continuous. It is concluded that serial section evaluation of the area encompassing die entire cavity as well as a few sections before and beyond the cavity zone should be considered for inclusion in die specifications.

Factors affecting the seating and fit of complete crowns: A computer simulation study

E ffective cementation is crucial to the successful placement of a complete crown, and poor seating results in inadequate marginal adaptation. Furthermore, an incompletely seated crown or fixed partial denture (FPD) compromises function.ls4 American Dental Association (ADA) specification No. 8 states that cement film thickness should not exceed 25 pm, but studies have demonstrated that the film thickness is frequently greater.5-” Burnishing subgingival crown margins to improve the marginal seal, particularly with ceramometal restorations, is impractical or impossible. I2 Therefore, the coping, the materials, and the crown cementation determine the quality of the seal. The effects of modifying technical and clinical procedures on seating have been repeatedly measured.5-‘4 However, clinical research is often limited by the experimental design, the technical difficulties of reproducing the unique orientation and fit of the coping to the die, or the consistency of the cement.*5,‘6 To overcome these problems, investigators have devised theoretical approaches to demonstrate fundamentals that influence the fit of crowns or crown cementation.17”9 A computer model was developed to combine the benefits of precision theoretical analysis and clinically applicable experimental design to reproduce several experimental studies.*, “r “3 21 This investigation applied the computer model in simulation of crown cementation under various clinical conditions.

American National Standards Institute / American Dental Association Specification No. 14 for Dental Base Metal Casting Alloys / Revised American National Standards Institute / American Dental Association Specification No. 14 for Dental Base Metal Casting Alloys

American National Standards Institute / American Dental Association Specification No. 14 for Dental Base Metal Casting Alloys / Revised American National Standards Institute / American Dental Association Specification No. 14 for Dental Base Metal Casting Alloys

Addendum to American National Standards Institute / American Dental Association Specification No. 19 for Dental Elastomeric Impression Material

Addendum to American National Standards Institute / American Dental Association Specification No. 19 for Dental Elastomeric Impression Material

American National Standards Institute / American Dental Association specification no. 46 for dental chairs

American National Standards Institute / American Dental Association specification no. 46 for dental chairs

Revised American National Standards Institute I American Dental Association Specification No. 23 for Dental Excavating Burs / American National Standards Institute / American Dental Association Specification No. 58 for Root Canal Files, Type H (Hedstrom)

Revised American National Standards Institute I American Dental Association Specification No. 23 for Dental Excavating Burs / American National Standards Institute / American Dental Association Specification No. 58 for Root Canal Files, Type H (Hedstrom)

Revised American National Standards Institute / American Dental Association Specification No. 28 for Root Canal Files and Reamers, Type K

Revised American National Standards Institute / American Dental Association Specification No. 28 for Root Canal Files and Reamers, Type K