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PubMedDate not supplied

Incisal-edge strength of porcelain laminate veneers restoring mandibular incisors.

Porcelain laminate veneers can be used to increase incisal-edge length. The purpose of this study was to determine the fracture resistance of porcelain veneer restorations on Cymel 1077 mandibular incisors that were incisally reduced 0.0, 0.5, 1.0, and 2.0 mm. Variables studied were incisal-edge length and the angle of applied force. Sixty-one porcelain laminate veneers were made to restore incisal-edge length and bonded to the prepared teeth. Samples were fractured at force angles of 130 degrees and 137 degrees. No significant difference was found between varying incisal-edge lengths (P > .05). However, the lower applied angle required greater average force to fracture (P = .005) as tested by ANOVA.

Analysis of Variance↗
PubMed2003

Method for immediate measurement of in vitro bond strength of bonded direct esthetic restorations.

There are many different ways to measure the bond strength of direct esthetic restorations to various dental substrates. Unfortunately, most methods cannot measure bond strengths immediately after a restoration has been placed. This lack of clinically-relevant information seriously affects the clinician's ability to select and use various bonding agents and procedures. The aim of this article is to provide a very detailed method for immediate measurement of in vitro bond strengths of direct bonded esthetic restorations. It focuses on the steps that should be taken to select and prepare various tooth substrates for bond strength testing, the steps to "restore" various tooth substrates, and to measure the immediate in vitro bond strength. A fundamental understanding of a standardized testing protocol should provide clinicians with a clearer appreciation of bond strengths associated with various bonding procedures.

Dental Bonding↗
PubMed2003

Flow, strength, stiffness and radiopacity of flowable resin composites.

OBJECTIVE: This study was undertaken to characterize 9 currently available proprietary flowable composites with respect to key properties of flow, flexural strength, stiffness (modulus of elasticity) and radiopacity. METHODS: Seven proprietary flowable composites (Aelite Flo, Filtek Flow, Heliomolar Flow, PermaFlo, Revolution Formula 2, Tetric Flow, Wave) and 2 flowable compomers (Compoglass Flow, Dyract Flow) were evaluated. A universal hybrid composite (Filtek Z250) and a restorative compomer (Dyract AP) were used as controls. Standard mechanical testing of 25 x 2 x 2 mm bar specimens was carried out at 24 hours and 1 month. Flow testing used a fixed volume of material under consistent loading, and radiopacity was measured simultaneously for all materials using disk specimens of 1 mm thickness. RESULTS: As expected, flowable composites showed higher flow and lower mechanical properties than the controls. Moduli of the composites were approximately 50% or less of the moduli of control materials, which indicates high flexibility. Flexural strengths approached that of the control composite. Flow properties varied widely. The material Tetric Flow had the highest radiopacity, above that of enamel and the control composite. Lowest radiopacity, below or equivalent to that of dentin, was shown by Wave and Revolution Formula 2. CONCLUSIONS: The flowable materials possessed a wide range of mechanical and physical properties. Their lower mechanical properties suggest that they should not be used in bulk in areas of high occlusal loading. Within intracoronal restorations, clinicians are advised to use materials with high radiopacity. A wide range of fluidity options is available. The clinical applications and performance of these materials require further study.

Analysis of Variance↗
PubMedDate not supplied

Oral rehabilitation of young adults with amelogenesis imperfecta.

PURPOSE: This article describes the restorative management of two patients in whom the diagnosis of amelogenesis imperfecta was not made until young adulthood. MATERIALS AND METHODS: Amelogenesis imperfecta is a variable developmental abnormality of the tooth enamel that affects relatively few persons. Previous case reports have focused largely on the early management of children and young adolescents. However, some patients may not be diagnosed correctly or may not request dental treatment until they are older, as with the two cases presented. In some instances, parents fail to appreciate the importance of early intervention. RESULTS: Both patients required intensive preventive therapy and extensive restorative treatment over several years. The correct sequencing of treatment phases was required to achieve relief of pain and provide satisfactory function and esthetics. CONCLUSION: The two cases presented illustrate the degree of complexity that extended restorative treatments can involve, especially following severe tooth wear and poor bonding of restorations to the affected enamel.

Adolescent↗
PubMed1992

Adhesive strength between teeth and resin cements for porcelain laminate veneer.

We performed an experiment on adhesive strength between teeth and resin cements for porcelain laminate veneer. A compression shear test was performed using three types of resin cement in extracted human anterior teeth. In dentin, the effects of various surface treatment methods were also evaluated. All three types of resin cement showed high adhesive strengths to enamel, but low adhesive strengths to dentin that were less than 1/2 of those to enamel. Treatment of the dentin surface with both a surface treatment agent and primer significantly increased adhesive strength.

Acid Etching, Dental↗
PubMed1992

Effect of axial load and temperature cycling on microleakage of resin restorations.

This study evaluated the microleakage of Class V resin restorations subjected to temperature and axial load cyclings. The preparations were made at the mesial and distal aspects of 29 mandibular first and second molars. The enamel margins were beveled, acid etched, washed and dried. Kerr XR Bonding System was applied to the dentin and etched enamel and Herculite composite cured in two increments. The teeth were stored in saline for 7 days, thermocycled x500 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C (A); subjected to an occlusal load of 34 MPa in the dye without thermocycling (B); or followed by thermocycling (C). The leakage was scored from 0 to 4 at both the enamel and cementum aspects of the restorations. The data were analyzed by the Kruskal-Wallis test. The microstrain of five restored teeth subjected to an occlusal load of 34 MPa was measured. Microleakage of the mesial restorations was significantly greater at the cementum aspects of the restorations subjected to both temperature and occlusal loading when compared to the restorations subjected to temperature cycling or load cycling only. The microstrain in eight of the 10 restorations was significantly greater at the cementum aspects of the restorations than at the enamel aspects.

Bite Force↗
PubMedDate not supplied

Direct oven-tempered hybrid composite-resin laminate veneers.

The difficulty in achieving optimal aesthetics of the single-tooth indirect laminate veneer has prompted the author to develop a direct technique for fabricating oven-tempered hybrid composite resin veneers. These restorations exhibit excellent physical properties, marginal integrity, and aesthetics.

Acrylic Resins↗
PubMedDate not supplied

25 years of veneering: what have we learned?

This is a review of the research completed over the 25 years in which dentists have been veneering teeth. Recommendations are made relative to the tooth preparation design for composite resin veneers and porcelain veneers. Material differences in a variety of applications are discussed together with recommended applications, indications and contraindications. From the research that has been reviewed, a series of best practices in the application of veneering materials and techniques is listed.

Composite Resins↗
PubMedDate not supplied

Fracture resistance of teeth with Class II bonded amalgam and new tooth-colored restorations.

This study compared the cuspal fracture resistance of posterior teeth restored with four different adhesive restorations. Fifty sound, maxillary human premolars were randomly divided into a control group and four experimental groups with 10 teeth in each. Specimens in the first group were intact teeth that were tested as unprepared. The remaining four groups received mesio-oclusodistal cavity preparations and were restored with a hybrid composite (Filtek Z250), a packable composite (Filtek P60), an ormocer (Definite) and an amalgam (SDI Permite) with an amalgam bonding agent (Amalgam Bond Plus). All groups were stored in water at 37 degrees C for 15 days and thermocycled 1000 times between 5 degrees-55 degrees C. The specimens were preloaded five times in compression to 10 kg using two metal rods that contacted only the teeth on the cuspal inclines. The teeth were then loaded occlusally in an Instron Universal Testing Machine until fracture occurred. The means of force required to fracture the teeth in each of the five groups was analyzed using one-way ANOVA and Tukey Test. The difference between the mean cuspal fracture resistance of the unprepared control teeth and those restored with amalgam groups was found to be statistically significant (p < 0.05). No significant differences in resistance to cuspal fracture were found among the restoration groups, the unprepared control group and those teeth restored with hybrid composite, packable composite and ormocer groups (p > 0.05).

Analysis of Variance↗
PubMedDate not supplied

Effect of food-simulating liquids on the shear punch strength of composite and polyacid-modified composite restoratives.

This study evaluated the effects of food-simulating liquids on the shear punch strength of two composites (Tetric Ceram [TC], Vivadent; Esthet X [EX], Dentsply), a conventional (Compoglass [CG], Vivadent) and a posterior polyacid-modified (Dyract Posterior [DP], Dentsply) composite. Thirty-two specimens (10-mm in diameter and 1.6-mm thick) of each material were made, randomly divided into four groups of eight and conditioned for one week as follows--Group 1 (control): air at 37 degrees C; Group 2: distilled water at 37 degrees C; Group 3: 75% ethanol-water solution at 37 degrees C and Group 4: heptane at 37 degrees C. After conditioning, the specimens were restrained within the test apparatus and subjected to shear punch strength testing using a 3.2 mm diameter punch at a crosshead speed of 0.5 mm/minute. The shear punch strength of the specimens was computed and the data was subjected to ANOVA/Scheffe's tests at significance level 0.05. The effect of food-simulating liquids on shear strength was found to be material dependent. All materials with the exception of EX were significantly weakened by ethanol solution. For DP, a significant increase in strength was observed after conditioning in water. EX was significantly stronger than TC and DY after conditioning in air, water and ethanol solution. The shear punch strength of EX and CG was significantly higher than DY after conditioning in heptane.

Analysis of Variance↗
PubMedDate not supplied

Measurement of band displacement: a methodology to determine composite packability.

OBJECTIVE: A posterior composite should be able to maintain its shape when packed against a matrix band. The objective of this study was to develop an in vitro methodology to determine composite packability by measuring the displacement of a matrix band. METHOD AND MATERIALS: The experimental setup consisted of a sectional matrix system secured for the restoration of an occlusodistal cavity preparation. The distance the band was displaced was measured from superimposed digital images. First, band displacements were measured under applied forces of 25, 50, and 75 g for different loading orders. Different forces resulted in different band displacements. Loading order significantly affected band displacements. Thus, the reproducibility of the experimental setup is ensured provided the band is replaced after each test. The cavity was filled with a universal composite (Z100, 3M ESPE) or a posterior composite (Filtek P60, 3M) at 37 degrees C. RESULTS: The band displacements were 32 +/- 28 pm vs 107 +/- 38 microm for Z100 and Filtek P60, respectively. CONCLUSION: The present study proposed measuring band displacement as an in vitro methodology to determine the packability of dental composite. Based on the result, the posterior composite should help in forming contact better than the universal composite tested.

Analysis of Variance↗