Influence of Implant Angulation With Different Crowns on Stress Distribution

The aim of this study was to perform a photoelastic analysis of stress distribution on straight and angulated implants with different crowns (screwed and cemented). Three models were made of photoelastic resin PL-2: model 1: external hexagon implant 3.75 x 10.00 mm at 0 degrees; model 2: external hexagon implant 3.75 x 10.00 mm at 17 degrees; model 3: external hexagon implant 3.75 x 10.00 mm at 30 degrees. Axial and oblique (45 degrees) load (100 N) was applied with a universal testing machine. The photoelastic fringes on the models were recorded with a digital camera and visualized in a graphic software for qualitative analysis. The axial loading generated the same pattern of stress distribution. The highest stresses were concentrated between medium and apical thirds. The oblique loading generated a similar pattern of stress distribution in the models with similar implant angulation; the highest stress was located on the cervical region opposite to implant angulation and on the apical third. It was concluded that the higher the implant angulation, the higher the stress value, independent of crown type. The screwed prostheses exhibited the highest stress concentration. The oblique load generated higher stress value and concentration than the axial load.

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)

Effect of Resin Cement System and Root Region on the Push-out Bond Strength of a Translucent Fiber Post

Objectives: This study evaluated the bond strength of luting systems for bonding glass fiber posts to root canal dentin. The hypothesis tested was that there are no differences in bond strength of glass fiber posts luted with different cement systems.Methods: Forty bovine incisors were randomly assigned to five different resin cement groups (n=8). After endodontic treatment and crown removal, translucent glass fiber posts were bonded into the root canal using five different luting protocols (self-cured cement and etch-and-rinse adhesive system; dual-cured cement and etch-and-rinse adhesive system; self-cured cement and self-etch adhesive system; dual-cured cement and self-etch adhesive system; and dual-cured self-adhesive cement). Push-out bond strength was evaluated at three different radicular levels: cervical, middle, and apical. The interface between resinous cement and the post was observed using a stereoscopic microscope.Results: Analysis of variance showed a statistically significant difference among the cements (p<0.05) and the root canal thirds (p<0.05). The self-adhesive resinous cement had lower values of retention.Conclusions: The resin cements used with etch-and-rinse and self-etch adhesive systems seem to be adequate for glass fiber post cementation.

Effect of Cement Type, Relining Procedure, and Length of Cementation on Pull-out Bond Strength of Fiber Posts

Introduction: As opposed to the cementation metal posts, the cementation of fiber posts has several details that can significantly influence the success of post retention. This study evaluated the effect of the relining procedure, the cement type, and the luted length of the post on fiber posts retention. Methods: One hundred eighty bovine incisors were selected to assess post retention; after endodontic treatment, the canals were flared with diamonds burs. Post holes were prepared in lengths of 5, 7.5, and 10 mm; the fiber posts were relined with composite resin and luted with RelyX ARC, RelyX Unicem, or RelyX Luting 2. All cements are manufactured by 3M ESPE (St. Paul, MN). Samples were subjected to a pull-out bond strength test in a universal testing machine; the results (N) were submitted to a three-way analysis of variance and the Tukey post hoc test (alpha = 0.05). Results: The improvement of post retention occurred with the increase of the post length luted into the root canal; the relining procedure improved the pull-out bond strength. RelyX Unicem and RelyX ARC showed similar values of retention, both showing higher values than RelyX Luting 2. Conclusion: Post length, the reining procedure, and the cement type are all important factors for improving the retention of fiber posts. (J Endod 2010;36:1543-1546)

The influence of ultrasound on the retention of cast posts cemented with different agents

Aim: The aim of this study was to evaluate the influence of ultrasound during the removal of posts cemented with either zinc phosphate cement, glass ionomer cement or resin cement. Methodology: Eighty-four single-rooted teeth were prepared and after cementation of cast posts, they were randomly divided into six groups of 14. Groups 1, 2 and 3 did not receive ultrasonic vibration, whilst groups 4, 5 and 6 received ultrasonic vibration for 10 min. The force necessary for post removal was determined using a universal testing machine. Results were statistically analysed using ANOVA and Tukey tests (5%). Results: The application of ultrasonic vibration reduced the retention provided by zinc phosphate and glass ionomer cements by 39% and 33%, respectively. Conclusions: A statistically significant reduction in the force necessary to remove posts cemented with zinc phosphate and glass ionomer cements occurred following application of ultrasound. The application of ultrasonic vibration did not influence the retention of cast posts cemented with resin cement.

Clinical evaluation of a composite resin and a resin-modified glass-ionomer cement in non-carious cervical lesions: One-year results

Objectives: The objective of this study was to evaluate the clinical performance of 124 non-carious cervical lesion restorations at 12 months. Materials And Methods: Three study groups were formed according to the material and technique used. All teeth received 37% phosphoric acid etching in enamel and dentin. The teeth of Group I received the conventional adhesive system Scotch Bond Multi Purpose, followed by resin composite Filtek Z350; teeth of Group II were restored with resin-modified glassionomer cement Fuji II LC; teeth of Group III were restored with the same resin-modified glass-ionomer cement-however, before it was inserted, 2 coats of primer of the Scotch Bond Multi Purpose adhesive system were applied to dentinal tissue. The teeth were evaluated by 2 examiners with regard to the factors of retention, marginal adaptation, marginal discoloration, color alteration, presence of marginal caries lesion, anatomic shape, and sensitivity. Results: Application of the Kruskal-Wallis test showed no statistically significant difference for anatomic shape, marginal discoloration, color alteration, caries lesion, marginal adaptation, and sensitivity among the three study groups, but the variable retention presented statistically significant difference at 12 months, with Group III presenting a behavior superior to that of Group II but similar to that of Group I. Conclusion: The analyzed restorations of non-carious cervical lesions presented a good clinical performance at 12 months. © 2012 Nova Science Publishers, Inc.

In vitro comparisons of casting retention on implant abutments among commercially available and experimental castor oil-containing dental luting agents

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

Influence of Insertion Techniques for Resin Cement and Mechanical Cycling on the Bond Strength Between Fiber Posts and Root Dentin

Purpose: To evaluate the effect of the insertion technique for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin.Materials and Methods: Sixty-four single-rooted bovine teeth were endodontically prepared to receive glass-fiber posts. The insertion of cement into the root canal was performed using one of the following techniques: POS, insertion with the post; LEN, the use of a lentulo-type drill; EXP, insertion with a straight-tip explorer; or CEN, the use of a Centrix syringe. Half of the specimens were mechanically cycled. All specimens were sectioned into slices of 1.8 mm for the push-out test and 0.5 mm for analysis of the cement layer quality.Results: The insertion technique affected the interaction between factors (bond strength and mechanical cycling; p < 0.0001). Insertion of the Centrix syringe after mechanical cycling showed the highest bond values (13.6 +/- 3.2 MPa). Group-to-group comparisons for baseline and cycled conditions indicated that mechanical cycling significantly influenced the bond strength (p < 0.0001) of the POS and CEN groups. The quality of the cement layer did not differ between the techniques when evaluated in the middle (p = 0.0612) and cervical (p = 0.1119) regions, but did differ in the apical region (p = 0.0097), where the CEN group had better layer quality for the two conditions tested (baseline and cycled).Conclusion: The use of the Centrix syringe improved the homogeneity of the cement layer, reducing the defects in the layer and increasing adhesive strength values to dentin, even after mechanical cycling.

Clinical evaluation of a composite resin and a resin-modified glass-ionomer cement in non -carious cervical lesions: one year result

Objectives: The objective of this study was to evaluate the clinical performance of 124 non-carious cervical lesion restorations at 12 months. Materials And Methods: Three study groups were formed according to the material and technique used. All teeth received 37% phosphoric acid etching in enamel and dentin. The teeth of Group I received the conventional adhesive system Scotch Bond Multi Purpose, followed by resin composite Filtek Z350; teeth of Group II were restored with resin-modified glass-ionomer cement Fuji II LC; teeth of Group III were restored with the same resin-modified glass-ionomer cement however, before it was inserted, 2 coats of primer of the Scotch Bond Multi Purpose adhesive system were applied to dentinal tissue. The teeth were evaluated by 2 examiners with regard to the factors of retention, marginal adaptation, marginal discoloration, color alteration, presence of marginal caries lesion, anatomic shape, and sensitivity. Results: Application of the Kruskal-Wallis test showed no statistically significant difference for anatomic shape, marginal discoloration, color alteration, caries lesion, marginal adaptation, and sensitivity among the three study groups, but the variable retention presented statistically significant difference at 12 months, with Group III presenting a behavior superior to that of Group II but similar to that of Group I. Conclusion: The analyzed restorations of non-carious cervical lesions presented a good clinical performance at 12 months.

Co-feeding of live feed and inert diet from first-feeding affects Artemia lipid digestibility and retention in Senegalese sole (Solea senegalensis) larvae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dietary supplementation of lysine and/or methionine on performance, nitrogen retention and excretion in pacu Piaractus mesopotamicus reared in cages

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

Soil water retention and s index after crop rotation and chiseling

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

Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Retention of oral microorganisms on conventional and resin-modified glass-ionomer cements

A cárie secundária representa problema de saúde pública e socioeconômico no mundo. A restauração de dentes acometidos por cárie pode criar condições favoráveis à proliferação microbiana na superfície do material restaurador ou na interface dente/restauração, criando ambiente propício para o estabelecimento de cárie secundária. O objetivo deste estudo foi avaliar a capacidade de retenção de placa bacteriana em cimentos de ionômero de vidro convencionais (Chelon-Fil e Vidrion R) e modificados por resina (Vitremer e Fuji II LC) e de resina composta híbrida (Z100), utilizada como controle. Nos testes de retenção de microrganismos, in situ, 12 voluntários utilizaram, por 7 dias, placa de Hawley contendo corpos-de-prova de todos os materiais. A seguir, os corpos-de-prova foram transferidos para tubos contendo 2,0 ml de Ringer-PRAS e os microrganismos presentes em sua superfície foram cultivados em placa com ágar-sangue e ágar Mitis Salivarius Bacitracina, os quais foram incubados, a 37ºC, em anaerobiose (90% N2, 10% CO2), por 10 e 2 dias, respectivamente. Os ionômeros modificados por resina retiveram quantidade de bactérias similar àquela mostrada pela resina testada. Os ionômeros modificados por resina também apresentaram menor número de estreptococos do grupo mutans do que a resina e os cimentos ionoméricos convencionais. Os ionômeros de vidro convencionais apresentaram menor número de estreptococos do grupo mutans que a resina, sendo que essa diferença não foi estatisticamente significativa.