Effect of an acrylic resin combined with an antimicrobial polymer on biofilm formation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Weight loss and changes in surface roughness of denture base and reline materials after simulated toothbrushing in vitro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of water storage and heat treatment on the cytotoxicity of soft liners

Objective: To evaluate the effect of water storage time on the cytotoxicity of soft liners.Methods: Sample discs of soft liners Dentusoft, Dentuflex, Trusoft, Ufi-Gel-P and denture base acrylic resin Lucitone-550 were prepared and divided into four groups: GN: No treatment, G24: Stored in water at 37 degrees C for 24 h; G48: Stored in water at 37 degrees C for 48 h, GHW: Immersed in water at 55 degrees C for 10 min. To analyse the cytotoxic effect, three samples of each group were placed in tubes with Dubelcco's Modified Eagle Mediums and incubated at 37 degrees C for 24 h. During this period, the toxic substances were leached to the culture medium. The cytotoxicity was analysed quantitatively by the incorporation of radioactivity H-3-thymidine checking the number of viable cells (synthesis of DNA). The data were statistically analysed using two-way ANOVA and Tukey's honestly significant difference tests (alpha = 0.05).Results: Treatments did not reduce the cytotoxicity effect of the soft liners (p > 0.05). It was found that Ufi-Gel-P had a non-cytotoxic effect, Trusoft had a slightly cytotoxic effect, Dentuflex had a moderated cytotoxic effect, Dentusoft alternated between slightly and non-cytotoxic effect, and Lucitone-550 had non-cytotoxic effect when stored in water for 48 h.Conclusion: The effect of water storage and the heat treatment did not reduce the cytotoxicity of the soft liners.

Effect of long-term water immersion on the fracture toughness of denture base and reline resins

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of Candida albicans adhesion and biofilm formation on a denture base acrylic resin containing silver nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

CORRELATING THE CURVE DISTANCE BETWEEN THE DISTAL of THE CANINES TO THE COMBINED WIDTH of THE SIX ANTERIOR TEETH WHEN SELECTING DENTURE TEETH FOR DIFFERENT ETHNIC GROUPS

Statement of problem. To select the width of denture teeth, the distance between the marks indicating the location of the canines is usually measured around the curvature of the wax occlusal rim; however, most manufacturers' mold charts provide the measurements of the artificial 6 anterior teeth as if they were on a straight line.Purpose. The purpose of this study was to investigate whether the curve distance between the distal surfaces of the maxillary canines can be related to the combined width (straight measurement) of the 6 anterior teeth in 4 ethnic groups.Material and methods. Maxillary stone casts were obtained for 160 dentate subjects of 4 ethnic groups (40 whites, 40 blacks, 40 multiracial - descendants of white and black parents, and 40 Asians). The width of each maxillary anterior tooth was measured on the casts with sliding calipers. The combined width of the 6 anterior teeth (CW) corresponded to the sum of the width of each anterior tooth. The curve distance between the distal surfaces of the canines (CD) was measured by using dental tape and sliding calipers. The Pearson correlation coefficient and regression analysis were used to evaluate the relationship between CD and CW in each ethnic group (alpha=.05).Results. The mean CD and CW values (in mm) obtained were: whites (CD=52.12; CW=45.65); blacks (CD=56.10; CW=48.13); multiracial (CD=53.58; CW=46.54); and Asians (CD=53.29; CW=46.60). Significant (P<.001) correlations between CD and CW measurements were observed for all ethnic groups studied (whites, r=0.957; blacks, r=0.803; multiracial, r=0.917; and Asians, r=0.881). The following linear regression equations were obtained: whites [CD=1.1(CW)+0.3]; blacks [CD=0.95(CW)+9.3]; multiracial [CD=1.2(CW)-1.1]; and Asians [CD=1.0(CW)+5].Conclusions. The curve distance between the distal surfaces of the maxillary canines can be accurately related to the combined width of the 6 anterior teeth in the selection of denture teeth for the studied ethnic groups. (J Prosthet Dent 2012;107:400-404)

THE EFFECT of DIFFERENT SURFACE TREATMENTS on THE SHEAR BOND STRENGTH of LUTING CEMENTS TO TITANIUM

Statement of problem. Although titanium presents attractive physical and mechanical properties, there is a need for improving the bond at the titanium/luting cement interface for the longevity of metal ceramic restorations.Purpose. The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of resin-modified glass ionomer and resin cements to commercially pure titanium (CP Ti).Material and methods. Two hundred and forty CP Ti cast disks (9.0 x 3.0 mm) were divided into 8 surface treatment groups (n=30): 1) 50 mu m Al2O3 particles; 2) 120 mu m Al2O3 particles; 3) 250 mu m Al2O3 particles; 4) 50 mu m Al2O3 particles + silane (RelyX Ceramic Primer); 5) 120 mu m Al2O3 particles + silane; 6) 250 mu m Al2O3 particles + silane; 7) 30 mu m silica-modified Al2O3 particles (Cojet Sand) + silane; and 8) 120 mu m Al2O3 particles, followed by 110 mu m silica-modified Al2O3 particles (Rocatec). The luting cements 1) RelyX Luting 2; 2) RelyX ARC; or 3) RelyX U100 were applied to the treated CP Ti surfaces (n=10). Shear bond strength (SBS) was tested after thermal cycling (5000 cycles, 5 degrees C to 55 degrees C). Data were analyzed by 2-way analysis of variance (ANOVA) and the Tukey HSD post hoc test (alpha=.05). Failure mode was determined with a stereomicroscope (x20).Results. The surface treatments, cements, and their interaction significantly affected the SBS (P<.001). RelyX Luting 2 and RelyX U100 exhibited similar behavior for all surface treatments. For both cements, only the group abraded with 50 mu m Al2O3 particles had lower SBS than the other groups (P<.05). For RelyX ARC, regardless of silane application, abrasion with 50 mu m Al2O3 particles resulted in significantly lower SBS than abrasion with 120 mu m and 250 mu m particles, which exhibited statistically similar SBS values to each other. Rocatec + silane promoted the highest SBS for RelyX ARC. RelyX U100 presented the highest SBS mean values (P<.001). All groups showed a predominance of adhesive failure mode.Conclusions. The adhesive capability of RelyX Luting 2 and RelyX U100 on the SBS was decisive, while for RelyX ARC, mechanical and chemical factors were more influential. (J Prosthet Dent 2012;108:370-376)

Evaluation of the occlusion vertical dimension of complete dentures after microwave disinfection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efficacy of Air-abrasion Technique and Additional Surface Treatment at Titanium/Resin Cement Interface

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Prevalence of Candida spp. associated with bacteria species on complete dentures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxicity of denture base and hard chairside reline materials: a systematic review

Statement of problem. Adverse reactions to the materials used for the fabrication and reline of removable denture bases have been observed.Purpose. The purpose of this study was to systematically review the published literature on the cytotoxicity of denture base and hard reline materials.Material and methods. MEDLINE via PubMed, Google Scholar, and Scopus databases for the period January 1979 to December 2009 were searched with the following key words: (biocompatibility OR cytotoxic* OR allergy OR burning mouth OR cell culture techniques) and (acrylic resins OR denture OR monomer OR relin* OR denture liners). The inclusion criteria included in vitro studies using either animal or human cells, in which the cytotoxicity of the denture base and hard chairside reline resins was tested. Studies of resilient lining materials and those that evaluated other parameters such as genotoxicity and mutagenicity were excluded. Articles published in the English language and in peer-reviewed journals focusing on the cytotoxicity of these materials were reviewed.Results. A total of 1443 articles were identified through the search. From these, 20 studies were judged to meet the selection criteria and were included in the review. In the majority of the studies, continuous cell lines were exposed to eluates of specimens made from the materials, and mitochondrial activity was used to estimate cell viability. The tested acrylic resins were grouped according to 5 major categories: (1) heat-polymerized; (2) microwave-polymerized; (3) autopolymerizing; (4) light-polymerized; and (5) hard chairside reliners.Conclusions. This review provided some evidence that the heat-polymerized resins showed lower cytotoxic effects than autopolymerizing denture base acrylic resins and light or dual polymerized reline resins. However, because of the large number of variables in the reviewed literature, a definitive conclusion could not be drawn. (J Prosthet Dent 2012;107:114-127)

Single crowns versus conventional fillings for the restoration of root filled teeth

BackgroundEndodontic treatment, involves removal of the dental pulp and its replacement by a root canal filling. Restoration of root filled teeth can be challenging due to structural differences between vital and non-vital root filled teeth. Direct restoration involves placement of a restorative material e.g. amalgam or composite directly into the tooth. Indirect restorations consist of cast metal or ceramic (porcelain) crowns. The choice of restoration depends on the amount of remaining tooth which may influence long term survival and cost. The comparative in service clinical performance of crowns or conventional fillings used to restore root filled teeth is unclear.ObjectivesTo assess the effects of restoration of endodontically treated teeth (with or without post and core) by crowns versus conventional filling materials.Search methodsWe searched the following databases: the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE via OVID, EMBASE via OVID, CINAHL via EBSCO, LILACS via BIREME and the reference lists of articles as well as ongoing trials registries. There were no restrictions regarding language or date of publication. Date of last search was 13 February 2012.Selection criteriaRandomised controlled trials (RCTs) or quasi-randomised controlled trials in participants with permanent teeth which have undergone endodontic treatment. Single full coverage crowns compared with any type of filling materials for direct restoration, as well as indirect partial restorations (e.g. inlays and onlays). Comparisons considered the type of post and core used (cast or prefabricated post), if any.Data collection and analysisTwo review authors independently assessed trial quality and extracted data.Main resultsOne trial judged to be at high risk of bias due to missing outcome data, was included. 117 participants with a root filled premolar tooth restored with a carbon fibre post, were randomised to either a full coverage metal-ceramic crown or direct adhesive composite restoration. At 3 years there was no reported difference between the non-catastrophic failure rates in both groups. Decementation of the post and marginal gap formation occurred in a small number of teeth.Authors' conclusionsThere is insufficient evidence to support or refute the effectiveness of conventional fillings over crowns for the restoration of root filled teeth. Until more evidence becomes available clinicians should continue to base decisions on how to restore root filled teeth on their own clinical experience, whilst taking into consideration the individual circumstances and preferences of their patients.

Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation

Background: This study evaluated the effect of disinfection by immersion and microwave irradiation on the roughness of one denture base resin (Lucitone-L) and five relining materials, three hard (Tokuyama Rebase II-TR, New Truliner-NT, Ufigel Hard-UH) and two resilient (Trusoft-T, Sofreliner-S).Methods: Fifty specimens were made and divided into groups: CL2 specimens were brushed with 4% chlorhexidine (1 min), immersed in the same solution (10 min) and immersed in water (3 min); MW2 specimens were immersed in water and microwave irradiated (650W; 6 min); CL2 and MW2 specimens were disinfected twice; CL7 and MW7 specimens were submitted to seven cycles using chlorhexidine or microwave irradiation, respectively; W specimens were not disinfected and remained in water (37 degrees C; 7 days).Results: Results were statistically analysed (p = 0.05) and revealed that, at baseline, the highest mean value was observed for T (p < 0.001). Material NT showed increase in roughness after the first (p = 0.003), second (p = 0.001), seventh (p = 0.000) cycles of microwave disinfection and after 7 days of immersion in water (p = 0.033).Conclusions: Resilient liner S presented significant increase in roughness after the second cycle of disinfection with chlorhexidine (p = 0.003). Material T exhibited significantly decreased roughness in group W (p = 0.010), while microwaving produced severe alterations on its surface.

Effectiveness of two disinfectant solutions and microwave irradiation in disinfecting complete dentures contaminated with methicillin-resistant Staphylococcus aureus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fracture strength of incisor crowns after intracoronal bleaching with sodium percarbonate

Objectives: To compare the fracture resistance of bovine teeth after intracoronal bleaching with sodium percarbonate (SPC) or sodium perborate (SP) mixed with water or 20% hydrogen peroxide (HP). Materials and methods: Fifty extracted bovine teeth were divided into four experimental groups (G1G4) and one control (n = 10) after endodontic treatment. Following root canal obturation, a glass ionomer barrier was placed at the cementoenamel junction. After that, the pulp chambers were filled with: G1 SP with water; G2 SP with 20% HP; G3 SPC with water; and G4 SPC with 20% HP. No bleaching agent was used in the control group. Coronal access cavities were sealed with glass ionomer and specimens were immersed in artificial saliva. The bleaching agents were replaced after 7 days, and teeth were kept in artificial saliva for an additional 7 days, after which the pastes were removed and the coronal access cavities were restored with glass ionomer. Crowns were subjected to compressive load at a cross head speed of 0.5 mm min-1 applied at 135 degrees to the long axis of the root by an EMIC DL2000 testing machine, until coronal fracture. Data were statistically analysed by anova and Tukey test. Results: No differences in fracture resistance were observed between the experimental groups (P > 0.05). However, all experimental groups presented lower fracture resistance than the control group (P < 0.05). Conclusion: SPC and SP led to equal reduction on fracture resistance of dental crowns, regardless of being mixed with water or 20% HP.