Different Post Placement Strategies for the Restoration of Endodontically Treated Maxillary Premolars with Two Roots: Single Post vs Double Post

Aim and objective: The present study compared the fracture strength and failure pattern of endodontically treated, bi-rooted, maxillary premolars with different number of coronal walls and postendodontic restoration (one vs double post). Materials and methods: 105 premolars were divided into 3 groups according to the number of residual walls: control group (intact teeth; n= 15), group 1 (3 residual walls; n = 45), group 2 (2 residual walls; n = 45). Each test group was then divided into 3 subgroups (n = 15 each) according to postendodontic restoration: no post (A), 1 post (B) or 2 posts (C). A load was applied parallel to the longitudinal axis of the teeth, thus simulating physiological occlusion. ANOVA and Tukey’s tests were used to detect fracture strength differences among groups, while Chisquare test was used to check differences in fracture pattern. Results: No significant differences were observed between control group (intact teeth) and groups A1 (p = 0.999), B1 (p = 0.997) and C1 (p = 1.000); statistically significant differences were detected between control group and groups A2 (p < 0.001), B2 (p < 0.001) and C2 (p < 0.05). Different post placement techniques were non-significantly associated with fracture pattern in both groups 1 (p = 0.666) and 2 (p = 0.143) while, irrespective of the number of posts, the presence of the post was significantly associated with the fracture pattern in teeth with two residual walls. The double-post technique did not further improve the fracture resistance of hardly damaged endodontically treated maxillary bi-rooted premolars compared to single-post technique. Therefore, the insertion of a single post in the palatal canal could be a safer and more conservative choice. Clinical significance: The double-post technique did not further improve the fracture resistance of severely structurally compromised endodontically treated maxillary premolars with two roots compared to the single-post technique. Therefore, the safer and less invasive treatment is the placement of a single post in the palatal canal

È il Torymus l’arma contro il Cinipide del castagno.

L’imenottero Dryocosmus kuriphilus Yasumatsu, conosciuto anche come cinipide galligeno del castagno, è la maggiore minaccia per questa pianta. Ritrovato per la prima volta in Europa in provincia di Cuneo nel 2002. L’articolo informa del ritrovamento di questo fitofago in Basilicata e dei lanci programmati dell’imenottero parassitoide Torymus sinensis Kamijo, come previsto dal piano nazionale

Shaping effectiveness and surface topography of reciprocating files after multiple simulated uses

This in vitro study assessed morphological changes and efficiency of reciprocating files after multiple uses. Sixty standardized Endo Training Blocks and 10 ReciprocR25 files were selected (six blocks for each file). Each file was its own control (before use vs. after each instrumentation). The instruments were used according to the manufacturer’s instructions, and scanning electron microscopy was used to observe fatigue cracks, metal strips/metal flash, pitting, fretting, debris, disruption of the cutting edge, and plastic deformations after each instrumentation. The presence of seven wear variables was scored semiquantitatively by viewing micrographs collected before and after use. The prepared areas in resin blocks were calculated and compared by using AutoCAD software. The control group had significantly lower values for all wear variables except fretting and plastic deformation. The presence of fatigue cracks and metal strips/metal flash significantly differed between unused instruments and instruments used four or five times, in all observed sections. The area of instrumented Endo Training Blocks significantly differed in relation to the number of instrument uses. The Reciproc files wore progressively, and repeated use affected their shaping efficiency in simulated canals

Influenza della variabile operatore sulla qualità dell'otturazione canalare: studio in vitro [Influence of operator-dependent-variable on the quality of root canal obturation: An in vitro study]

OBJECTIVES The aim of this study was to assess if the operator's experience could influence the quality of root canal fillings performed with two different techniques: continuous wave of condensation technique and carrier based technique. MATERIALS AND METHODS Sixty standardized endo-training- blocks in resin were used for this study. All blocks were divided into 3 groups of 20 each. A chosen operator was then assigned to each group based on his own clinical experience level: inexperienced, average expert, expert. Each operator has filled a group of endocranial block using the two different techniques. The 60 filled blocks were finally x-rayed and analyzed. RESULTS Statistically significative differences were observed between root canal fillings performed with carrier based technique by the expert operator and root canal fillings performed with continuous wave of condensation technique and carrier based technique by the inexperienced operator. Furthermore, statistically significative differences were observed as regard apical extension parameter, between canal filling performed with both techniques by the inexperienced operators. CONCLUSIONS Within the limits of this in vitro study, it was concluded that the control of apical extension was the standard which defined a better x-ray quality of root canal fillings, when realized by expert operators rather than when realized by inexperienced operators. When the inexperienced operator used continuous wave of condensation technique, obtained better results in terms of apical extension compared to carrier based technique

Push-out bond strength of fiber posts cemented using new universal adhesives on etched and nonetched intraradicular dentin

Aim: The aim of this study was to assess if the curing mode and the etching mode could affect the push-out bond strength of different post cementation systems using two universal adhesives. Materials and methods: A total of 100 single-rooted teeth were divided into Prime & Bond Elect (PBE), Prime & Bond Active (PBA), and Prime & Bond XP (PBXP) as a control. The PBE, PBA, and PBXP were used in the self-etch (SE) and etch and rinse (E&R) mode. Post cementation was performed using Core X flow used in dark-cure and in light-cure. Data were analyzed using the one-way ANOVA test and post hoc Bonferroni and Dunnet tests. The Student's t test was performed to find significance between two independent groups. Results: Bond strength was significantly influenced by the adhesive strategies. The PBE and PBA obtained higher values when used in the SE mode (p < 0.001). Light-cured groups obtained significantly higher values (p < 0.001) compared to dark-cured groups. The post space region also had a significant effect on the bond strength; the apical third recorded lower values in all groups (p < 0.001). Conclusion: The PBA and PBE universal adhesives obtained higher PBS values when used in the SE mode and followed by the light-curing of resin cement. Clinical significance: Universal adhesives represent a good alternative to the conventional total-etch adhesive system for fiber post cementation. Since they perform better in SE, they would be recommendable in clinical practice, as they can be used with a simplified technique. © 2020 The Author(s)

Influence of Access Cavity Preparation and Remaining Tooth Substance on Fracture Strength of Endodontically Treated Teeth

Introduction: The purpose of this study was to assess the impact of access cavity preparation and the remaining tooth substance on the fracture strength of endodontically treated teeth. Methods: One hundred sound mandibular first and second molar teeth were selected and divided into 1 control and 9 test groups (n = 10/group) as follows: control group, intact teeth; group 1, teeth prepared with traditional endodontic access cavity (TEC); group 2, teeth prepared with conservative endodontic access cavity (CEC); group 3, teeth prepared with truss endodontic access cavity (TREC); group 4, TEC + 3 residual walls; group 5, CEC + 3 residual walls; group 6, TREC + 3 residual walls; group 7, TEC + 2 residual walls; group 8, CEC + 2 residual walls; and group 9, TREC + 2 residual walls. After access cavity preparation, all test teeth were endodontically treated and restored. The specimens were then loaded to fracture in a universal loading machine (Triaxial Tester T400 Digital; Controls srl, Cernusco, Italy), and fracture values were recorded in newtons. The data were analyzed with 2-way analysis of variance and Tukey post hoc analysis for multiple comparisons (P <.05). Results: Intact teeth were more resistant to fracture than the teeth in all the test groups. No statistically significant differences were found between the 3 tested access cavities (P >.05). Significant differences were observed between the different number of residual walls (P <.05). Conclusions: TRECs do not increase the fracture strength of endodontically treated teeth in comparison with CECs and TECs. Moreover, the loss of mesial and distal ridges reduced the fracture strength of teeth significantly