Vulcanite or gutta-percha? That is the question

1991 ◽  
Vol 22 (5) ◽  
pp. 292-297
Author(s):  
Grahame Brown
Keyword(s):  
2018 ◽  
Vol 9 (1) ◽  
pp. 107-126
Author(s):  
Birgit Schneider

The article discusses how current mediated conditions change nature perception from a media study perspective. The article is based on different case studies such as the current sensation of atmospheric change through sensible media attached to trees which get published via Twitter, the meteorologist Amazonian Tall Tower Observatory and the use of gutta percha derived from tropical trees for the production of cables in the history of telegraphy. For analysing the examples, the perspective of »media as environments« is flipped to »environments as media«, because this focus doesn’t approach media from a networked and technological perspective primarily but makes productive the elemental character of basic »media« like air, earth and water


Author(s):  
Ralf Krug ◽  
C. Ortmann ◽  
S. Reich ◽  
B. Hahn ◽  
G. Krastl ◽  
...  

Abstract Objectives To assess tooth discoloration induced by different hydraulic calcium silicate-based cements (HCSCs), including effects of blood and placement method. Materials and methods Eighty bovine teeth cut to a length of 18 mm (crown 8 mm, root 10 mm) were randomly assigned to 10 groups (n = 8), receiving orthograde apical plug treatment (APT). Apical plugs were 4 mm in length and made of ProRoot MTA (Dentsply), Medcem MTA (Medcem), TotalFill BC RRM Fast Set Putty (Brasseler), or Medcem Medical Portland Cement (Medcem) plus bismuth oxide (Bi2O3) with and without bovine blood. Further, orthograde (with or without preoperative adhesive coronal dentin sealing) and retrograde APT were compared. Teeth were obturated with gutta-percha and sealer, sealed with composite and stored in distilled water. Tooth color was measured on apical plug, gutta-percha/sealer, and crown surface before treatment versus 24 h, 1, 3, 6, 12, and 24 months after treatment by spectrophotometry. Color difference (ΔE) values were calculated and analyzed by Shapiro–Wilk test, ANOVA with post hoc tests, Friedman test, t test, and post hoc tests with Bonferroni correction (α = .05). Results Tooth discoloration occurred in all groups with no significant differences between HCSCs (p > .05). After 24 months, color changes were prominent on roots but insignificant on crowns. Blood contamination induced a significantly decreased luminescence (p < .05). Blood had a stronger impact on tooth color than Bi2O3. No relevant effects of retrograde placement (p > .05) or preoperative dentin sealing (p > .05) were detected. Conclusions Apical plugs of the tested HCSCs cause discoloration of bovine roots, but not discoloration of bovine tooth crowns within a 24-month period. Clinical relevance APT should be performed carefully while avoiding direct contact with the coronal dentin, and in that case no aesthetic impairments occur.


2020 ◽  
Vol 9 (8) ◽  
pp. 2465
Author(s):  
Inês Ferreira ◽  
Pedro S. Babo ◽  
Ana Cristina Braga ◽  
Manuela E. Gomes ◽  
Irene Pina-Vaz

Background: This work aimed to evaluate the efficacy of sonic agitation of a binary mixture of solvents (methyl ethyl ketone/tetrachloroethylene) on filling remnants removal and compare the effects of solvent agitation with the enlargement to the next instrument size. Methods: Twenty-four mandibular incisors were prepared with ProTaper Next (X1, X2) and obturated with the single-cone technique and AH Plus sealer. The teeth were retreated with ProTaper Universal Retreatment and ProTaper Next and divided into two groups (n = 12) according to the final instrument (X3 or X4). All canals were submitted to a supplementary procedure consisting of a mixture of solvents―methyl ethyl ketone/tetrachloroethylene, agitated with EndoActivator. The volume of filling remnants was assessed through micro-computed tomography in the apical 5 mm. Statistical analysis was performed with a significance level of 5%. Results: The supplementary procedure of agitation of the solvent mixture was beneficial in both groups (p < 0.05). There were no statistically significant differences between canals re-prepared until X4 and canals re-prepared until X3 plus solvent (p > 0.05). Conclusions: An additional step with a two-solvent solution potentiated by EndoActivator showed to be very effective for the removal of gutta-percha and resinous sealer remnants from apical root canals of mandibular incisors, avoiding further enlargement.


1974 ◽  
Vol 37 (6) ◽  
pp. 946-953 ◽  
Author(s):  
Herbert Schilder ◽  
Alvin Goodman ◽  
Winthrop Aldrich

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