Effects of external bleaching on restorative materials: a review.

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.

Por que o clareamento dental caseiro deve ser feito sob a supervisão de um dentista? / Why should dental home bleaching be performed under the supervision of a dentist?

O objetivo deste artigo é demonstrar a importância de uma visita ao dentista por alguém interessado em clareamento dental. Mais do que nunca, as pessoas estão ansiosas por dentes mais brancos. Desde o aparecimento dos produtos de clareamento auto-administrados no início dos anos 2000, nunca foi tão fácil ter acesso a tantos tipos diferentes de produtos. Embora o processo de clareamento pareça ser simples, ele é um procedimento odontológico que precisa de um exame dentário prévio por diversas razões. O dentista não apenas conduzirá exames dentários e periodontais, mas também perguntará ao paciente sobre seu estado de saúde, para ter certeza de que não há contra-indicações. Ele diagnosticará a possível causa do manchamento dental e será capaz de determinar a chance de sucesso, a duração e o custo do tratamento e explicar os possíveis efeitos colaterais. O paciente também pode se beneficiar da supervisão do dentista, se quaisquer complicações surgirem durante o tratamento de clareamento. Uma discussão de todos esses aspectos é apresentada neste artigo.

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

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.

Fracture resistance of prepared teeth restored with bonded inlay restorations.

STATEMENT OF PROBLEM: 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

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

OBJECTIVES: A potential problem with high-intensity lights might be failure of polymer chains to grow and cross-link in a desired fashion, thereby affecting the structure and properties of the polymers formed. The purpose of this study was to evaluate mechanical properties of resin composites polymerized using four different light-curing units. METHODS: A conventional quartz-tungsten-halogen (QTH) light, a soft-start light, an argon-ion laser, and a plasma-arc curing light were used to polymerize disk-shaped (9.0mm diameter x 1.0 mm high) and cylinder-shaped (4mm diameter x 8 mm high) specimens of a universal hybrid and a flowable hybrid composite. Biaxial flexure strength, fracture toughness, hardness, compressive strength, and diametral tensile strength were determined for each composite. RESULTS: The use of the plasma-arc curing light, a high-intensity light, resulted in significantly lower hardness for the universal hybrid composite compared with the hardness obtained using the conventional QTH and the soft-start units. Hardness was the only mechanical property that was adversely affected by the use of a high-intensity light. SIGNIFICANCE: High-intensity lights might affect some resin composite mechanical properties, but this effect cannot be generalized to all resin composites and all properties.

Safety and stability of nightguard vital bleaching: 9 to 12 years post-treatment.

PURPOSE: The purposes of this retrospective case series study were to evaluate safety issues and determine participants' perceptions of a nightguard vital bleaching (NGVB) technique approximately 10 years post-treatment (average, 118 mo; range, 108-144 mo). MATERIALS AND METHODS: The study sample included 30 (79%) of 38 participants who had completed a previous NGVB study using a 10% carbamide peroxide solution (Proxigel or Gly-Oxide) in a custom tray for 6 weeks. Participants were asked whether there had been any change in the shade of their teeth post-treatment and, if so, to quantify the change on a verbal scale. In addition, 19 participants had gingival index and tooth vitality evaluated clinically, external cervical root anatomy evaluated radiographically, and enamel surface changes evaluated microscopically. RESULTS: Thirty-five (92%) of the original 38 participants had successful lightening of their teeth. At approximately 10 years post-treatment (average, 118 mo; range, 108-144 mo), external cervical resorption was not diagnosed and gingival index and tooth vitality findings were considered within the normal expectations for the sample studied, suggesting minimal clinical post-NGVB side effects at approximately 10 years. Scanning electron microscopic observations did not reveal substantial differences between treated and nontreated surfaces. Color stability, as perceived by 43% of the participants, may last approximately 10 years (average, 118 mo; range, 108-144 mo) post-treatment. CLINICAL SIGNIFICANCE: Nightguard vital bleaching using 10% carbamide peroxide is safe and effective, with no noticeable side effects, at approximately 10 years (average, 118 mo; range, 108-144 mo) post-treatment. Color stability, as perceived by 43% of the participants, may last 108 to 144 months post-whitening.

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

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.

Microleakage of Class V composites using different placement and curing techniques: an in vitro study.

PURPOSE: To evaluate microleakage at enamel and dentin margins of two composite resins, using bulk and incremental placement techniques, "rebonding", and facial and lingual curing methods. MATERIALS AND METHODS: One hundred standardized Class V cavity preparations were made on the facial surface of extracted human premolars and were randomly assigned to 10 groups. Single Bond was used as the dentin/enamel adhesive. A heavily filled composite resin, Z250, and a microfill, Silux Plus, were inserted and polymerized using five different techniques: (1) incremental placement and facial curing; (2) incremental placement, facial curing and rebonding; (3) bulk placement and facial curing; (4) bulk placement, facial curing and rebonding; (5) incremental placement and lingual and facial curing. After the restorations were finished and polished, the margins of those in the rebonded groups were etched, rinsed, and dried. The adhesive resin, Single Bond, was applied at the composite resin-tooth interface and light-cured. All the specimens were thermocycled, stained with 1% methylene blue, sectioned, and evaluated for leakage (0-4 scale) by two examiners. RESULTS: Almost no leakage occurred at enamel margins. At the cementum margins, differences in microleakage related to restorative material or technique were not statistically significant. However, leakage at the cementum margins was significantly greater than at the enamel margins for both composite resin materials.