Bonding effectiveness of adhesive luting agents to enamel and dentin.

Throughout life, women’s sexuality is more dependent on the existence and nature of a relationship with a partner than is that of men. The evidence that this is the case in adolescence, early adulthood, and middle and old age will be discussed in relation to these life stages. It may explain or result from the greater importance psychological (as opposed to biological) factors have on women’s sexuality as compared to men’s. Despite the overwhelming importance given in the United States to environmental as compared to biological variables in determining human behavior (McConaghy, 1987b), some of its theorists have considered the differences between the behavior of men and women to be genetically determined by the form of sexual activity selected in the evolution of human beings to enable the survival of their species (Knoth, Boyd, & Singer, 1988).

Age and Sex

How to simulate wear?: Overview of existing methods

https://www.dental.theclinics.com/article/S0011-8532(06)00132-7/pdf

Abrasive Finishing and Polishing in Restorative Dentistry: A State-of-the-Art Review

Purpose: The purpose of this in vitro study was to evaluate the surface finish and gloss of five direct resin composites polished with six polishing systems. Materials and Methods: One hundred and fifty disk-shaped composite specimens (D = 10.0 mm, 2-mm-thick, N = 30 per material) were made. One side of each specimen was finished with a 16-fluted carbide finishing bur and then polished. Five specimens of each resin composite were randomly assigned to one of the six polishing systems. The surface roughness and gloss were measured with a surface profilometer and a glossmeter. The results were analyzed by two-way analysis of variance and Tukey's t-test (p ≤ 0.05). Results: There was no significant interaction between the composite and the polishing systems for surface roughness (p = 0.059). The order of surface roughness ranked according to composite was: Durafill < Esthet-X < Supreme < Z250 < Z100; and the ranking for the polishing system was: Pogo < Sof-Lex < Diacomp/Enamelize < Diacomp < ComposiPro brush < Jiffy. There was interaction of gloss values between the composites and the polishing systems (p < 0.001). The highest gloss value was recorded for Supreme + Pogo; the lowest was recorded for Z100 + Jiffy. Pogo showed the highest gloss values for all composites. CLINICAL SIGNIFICANCE The nanofill (Supreme) and minifill (Esthet-X) composites presented a surface roughness compa- rable to a microfill (Durafill), independent of the polishing system used, and a gloss comparable to a microfill, when polished with a one-step system (Pogo). As compared with the multiple-step systems, the smoothest surfaces and the highest gloss values were achieved using the one-step system (Pogo) for all the evaluated composites. (J Esthet Restor Dent 19:214-226, 2007)

The effect of different polishing systems on surface roughness and gloss of various resin composites.

Statement of problem Tooth preparation weakens the remaining tooth structure. Purpose This study attempted to measure and compare the strength of intact, prepared, and restored human maxillary premolars. Material and methods Fifty intact, noncarious human maxillary premolars were divided into 5 groups of 10 and were mounted with their roots imbedded in autopolymerized acrylic. In the first group, the teeth were intact with no preparation. In the other 4 groups, Class II MOD preparations were made with a water-cooled high-speed hand piece. In 1 group, the cavity preparations were restored with bonded CAD/CAM ceramic inlays. In 2 groups, the preparations were restored with bonded CAD/CAM composite inlays (acid etched or air particle abraded). In the final group, the teeth were prepared but unrestored. Specimens were tested individually in a universal testing machine, in which a 4.82-mm-diameter steel sphere plunger was mounted in the crosshead moving at 0.5 mm/min. The plunger contacted the facial and lingual triangular ridges beyond the margins of the restorations. Peak load to fracture (N) was measured for each specimen. Means were calculated and analyzed with analysis of variance ( P ≤.05). Results MOD preparations weakened the teeth by approximately 59%. Restoring the teeth with ceramic or composite inlays did not significantly strengthen the teeth under this testing system. Of the restored teeth, those restored with indirect composite inlays cemented following manufacturer's recommendations had the highest fracture resistance. Conclusion Within the limitations of this study, under static compression load testing, bonded inlay restorations did not strengthen maxillary premolars with large MOD preparations.

Fracture resistance of prepared teeth restored with bonded inlay restorations.

With the increasingly commercial emphasis on dental esthetics, patients have become more interested in improving the appearance of their smile. For many, whiter teeth is their chief goal. However, when considering dental bleaching, practitioners need to take certain precautions. Over the past decade, multiple studies have evaluated the effects of bleaching agents on restorative materials. This article reviews their conclusions, focusing mainly on the clinical impact these agents can have on amalgam, porcelain, ormocer, glass ionomer, compomer and composite resin restorations.

Effects of external bleaching on restorative materials: a review.

Irradiance effects on the mechanical properties of universal hybrid and flowable hybrid resin composites

This study evaluated the surface finish of three direct resin composites polished with three different systems. Disk-shaped specimens (n=16 per material; phi=8.0 mm x h=2.0 mm) were formed in a stainless steel mold by packing uncured material, either a hybrid composite (Z250, 3M ESPE) or two micro-hybrid composites (Point 4, Kerr; Esthet-X, Dentsply), and light-cured from the top and the bottom surfaces with a light-emitting diode (LED) curing unit (NRG, Dentsply). After storing the specimens in deionized water at 37 degrees C for seven days, one side of each specimen was finished through 1200-grit SiC abrasive (Buehler). Five specimens of each resin composite were randomly assigned to one of the three polishing systems (Identoflex, Kerr; Pogo, Dentsply; Sof-Lex, 3M ESPE). Manufacturers' instructions were followed during the polishing procedures. The average surface roughness (Ra) was determined by generating tracings across the polished surface of each disk using a scanning profilometer (Surfanalyzer System 5000, Federal Products Co). The results were analyzed by Kruskal-Wallis and Mann and Whitney tests (p < or = 0.05). The smoothest surfaces were produced with the celluloid strip (control group) on all the resin composites tested. The aluminum oxide disks (Sof-Lex) produced a statistically equivalent surface finish (Ra) on the three resin composites. The lowest mean roughness values were recorded with diamond micropolisher disks (PoGo) on the hybrid composite (Z250). Overall, the two new polishing systems, Identoflex and PoGo, created a comparable surface finish to that produced by the Sof-Lex system on all three resin composites.

Surface finish produced on three resin composites by new polishing systems.

This in vitro study evaluated the wear resistance of resin composite polymerized using four different light-curing systems. For this, a well-defined cylindrical cavity preparation (4.0 mm in diameter x 3.0 mm in depth) was made in a ceramic block (n=4 per material/light condition). Uncured material, either a universal hybrid composite (Herculite XRV) or a flowable hybrid composite (Revolution Formula 2), was packed and light-cured from the top surface only with one of the four light-curing units: 1) a conventional quartz-tungsten-halogen light, 2) a soft-start light, 3) an argon-ion laser or 4) a plasma-arc curing light. After storing the specimens in deionized water at 37 degrees C for 24 hours, the excess cured material was ground through successive grits up to a final 1200-grit SiC abrasive. The specimens were placed in deionized water at 37 degrees C for an additional 24 hours. Wear simulation was performed using a four-station Leinfelder-type three-body wear device. A slurry of water and unplasticized polymethylmethacrylate beads, simulating an artificial food bolus, was placed on the surface of each resin-composite-restored ceramic block. The entire cycling procedure was carried out 400,000 times. Impressions of each resin composite surface were taken with polyvinylsiloxane and epoxy replicas were made. Wear analyses were conducted by generating tracings across the worn surface of epoxy replicas using profilometer scans. For the universal hybrid composite and the flowable hybrid composite, the lowest wear occurred in specimens that were cured using the conventional quartz-tungsten-halogen light, and the highest wear was detected on those specimens made using the argon-ion laser. For both resin composites, the mean wear for specimens cured using the argon-ion laser was significantly higher than that of the specimens cured with the three other lights, which were statistically similar.

Annie J St-Georges

Papers

Fracture resistance of prepared teeth restored with bonded inlay restorations.

Effects of external bleaching on restorative materials: a review.

Irradiance effects on the mechanical properties of universal hybrid and flowable hybrid resin composites

Surface finish produced on three resin composites by new polishing systems.

Curing light intensity effects on wear resistance of two resin composites.