Marginal sealing of relocated cervical margins of mesio-occluso-distal overlays.

We investigated the effect of cervical marginal relocation (CMR) on marginal sealing with two different viscosity resin composites, before adhesive cementation of composite computer-aided design/computer-assisted manufacture mesio-occluso-distal (MOD) overlays. Standardized MOD cavities prepared in 39 human molars were randomly assigned to three groups. The proximal margins on the mesial side were located 1 mm below the cementoenamel junction. On the distal side of the tooth, the margins were located 1 mm above the cementoenamel junction. In Groups 1 and 2, mesial proximal boxes were elevated with a hybrid composite (GC Essentia MD) and a flowable composite (GC G-ænial Universal Flo), respectively. CMR was not performed in Group 3. The overlays were adhesively cemented, and interfacial leakage was quantified by scoring the depth of silver nitrate penetration along the adhesive interfaces. Leakage score at the dentin-CMR composite interface did not significantly differ between the two tested composites but was significantly lower for Group 3. In all groups, scores were significantly higher at the dentin interface than at the enamel interface. These results indicate that the performance of flowable and microhybrid resin composites, as indicated by marginal sealing ability, is comparable for CMR

Evaluation of two endodontic irrigation needles on curved root canal disinfection: an ex vivo study

Aim: The study aimed to compare the effectiveness of two different irrigation needles in eliminating E. faecalis from contaminated curved root canals and to test their difference in flexibility. Materials and methods: Thirty-five extracted multirooted teeth with visible curved canals were instrumented, autoclaved at 121 °C for 25 minutes, and contaminated with 10 μL of the bacterial suspension. The teeth were randomly divided into three groups: A (IrriFlex), B (Navitip), and C (Control). After an incubation period of 21 days at 37 °C, group C was irrigated with 20 μL of sterile saline solution. Groups A and B were irrigated with 5 ml of 5% sodium hypochlorite (NaOCl) solution by inserting the respective needle tip until the apical third, neutralized with 5 mL of 5% sodium thiosulfate and rinsed with 5 mL of sterile saline. Three sterile paper points for each sample were taken, transferred into a brain heart infusion (BHI) medium under aseptic conditions, and frosted immediately at -20 °C. Colony-forming unit (CFU) counting was assessed after microbiological culture on selective media for E. faecalis. A customized device was used to test the bending behavior of the tips at 3 mm, 6 mm, and 9 mm. Kruskal-Wallis and Dunn tests were used for statistical analysis. Results: IrriFlex needle demonstrated higher flexibility with no statistical difference at 3 and 6 mm compared to NaviTip. NaOCl irrigation with NaviTip Tip and IrriFlex effectively reduced E. faecalis CFU count. Conclusions: NaOCl irrigation with NaviTip Tip and IrriFlex demonstrated high and comparable efficacy in removing E faecalis from curved canals of multirooted teeth

Influence of methodological variables on fracture strength tests results of premolars with different number of residual walls. A systematic review with meta-analysis

The aim of the current meta-analysis was to assess the impact of methodological variables in performing fracture strength tests of upper premolars. Medline (Pubmed), Embase and Google Scholar were screened for studies performing ex vivo fracture strength tests of intact upper premolars or premolars with 0, 1 or 2 walls lost. The outcome variable for each study was the maximum breaking load expressed in Newton (kg × m/s2 ). Methodological variables (i.e., simulation of the periodontal ligament, load inclination, tip position, tip diameter and thermocycling) were registered to perform subgroup analyses and meta-regression. Overall, 25 studies and 78 study groups were included in the meta-analysis. Intact premolars (17 study groups) were not significantly influenced by any of the methodological variables considered. Subgroup analysis for load inclination (30◦ /45◦ vs. 90◦ /150◦ ) was significant for premolars with 0 (10 study groups), 1 (6 study groups) and 2 (45 study groups) walls lost; thermocycling was significant for premolars with 1 and 2 walls lost. A strong methodological heterogeneity across studies evaluating the fracture strength of upper premolars was highlighted, especially when 0, 1 or 2 walls were lost. Further studies are needed to standardize the methodology used in order to allow for across-studies comparisons

Adherence to Mediterranean diet, physical activity level, and severity of periodontitis: Results from a university-based cross-sectional study

Background: The aim of this study was to evaluate the association between adherence to Mediterranean diet (MD) and physical activity (PA) level with the periodontal status of a University-based cohort of individuals. Methods: A total of 235 individuals were included in the study. MD adherence and PA level were registered through validated questionnaires, together with a full periodontal examination. Crude and adjusted odds ratios (ORs) [95% confidence interval] were calculated to evaluate the association between MD adherence, PA level, and periodontitis severity. A final logistic multivariate regression model was built to evaluate the impact of the combination between low MD adherence and low PA level on the prevalence of Stage III/IV periodontitis. Results: The adjusted ORs for Stage III/IV periodontitis were 1.65 [0.84 to 3.28; P = 0.42] for low PA and 5.63 [3.21 to 9.84; P = 0.00] for low MD adherence. The final logistic multivariate regression model resulted in OR = 10.23 [4.01, 26.09; P = 0.00] of having Stage III/IV periodontitis in individuals with low MD adherence and low PA. Conclusions: Individuals conducting a lifestyle characterized by the combination of low MD adherence and lack of regular exercise had 10 times the odds to have severe forms of periodontitis. © 2022 The Author

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

Influence of calcified canals localization on the accuracy of guided endodontic therapy: a case series study

This study aimed to evaluate the precision of the guided endodontic technique applied to calcified canals in anterior teeth in relation to demographic and dental variables. The present observational study was conducted during the period 2020–2021. The patients were consecutive referrals at the Department of Endodontics and Conservative Dentistry of the University Hospital of Siena. The guided endodontics protocol was applied using 0.75 mm diameter burs for the lower teeth and 0.90 mm for the upper teeth. The inclusion criteria were as follows: (i) teeth with pulp canal obliteration (PCO) associated with a periapical lesion (periapical index (PAI) ≥ 2); (ii) teeth with PCO that require the placement of a root canal post for the execution of a prosthetic treatment; (iii) teeth in which surgical treatment was not justified. Socio-demographic characteristics of the patients were recorded and related to the drill path accuracy through the guide in the calcified endodontic canal, evaluated through a radiographic analysis, and classified as optimal (in the center of the root canal) and acceptable (deviated peripherally/tangentially). A logistic regression model was built to predict the factors that influence the poor precision of the technique. Seventeen patients (mean age 48 years) with eighteen calcified single-rooted teeth were enrolled. All teeth were associated with periapical lesions with PAI scores from 2 to 5 (mean PAI: 3.055). From the model, it is evident that the presence of a calcification affecting the apical area of the root increases the probability of being off-center with the bur by about 15 times. In addition, a previous attempt at endodontic treatment and the position in the lower arch increases the probability of non-centrality of the drill, although in a non-statistically significant way. In any of the analyzed cases, the guided endodontic technique applied to PCO did not determine the presence of iatrogenic errors, such as perforations. However, the apical localization of the obliteration increases the probability of being off-center with the drill during the instrumentation phase by about 15 times

Comparison of the surface tension of 5.25% sodium hypochlorite solution with three new sodium hypochlorite-based endodontic irrigants

Aim To investigate the surface tension characteristics of 5.25% sodium hypochlorite and three recently introduced sodium hypochlorite solutions, which had been modified to reduce their surface tension: ChlorXtra, Hypoclean A and Hypoclean B. Methodology Freshly produced MilliQ water was used as a reference liquid. All measurements of surface tension were taken by the Wilhelmy plate technique, using a Cahn DCA-322 Dynamic Contact Angle Analyzer at the temperature of 22°C. A glow-discharge cleaned glass slide was immersed in 5 mL of the test liquid in a beaker cleaned with hot chromic acid, rinsed with MilliQ water and finally air plasma-cleaned in a glow-discharge reactor. The force on the glass slide was recorded continuously by the instrument software as the beaker was raised and withdrawn at the constant speed of 40 micron/s, until at least 1 cm of the glass slide was immersed. The typical accuracy was 0.5 mJ m ) had the highest surface tension values (P < 0.01) compared to ChlorXtra (33.14 mJ m ). Hypoclean A had the lowest surface tension (P < 0.01). Conclusions The new 5.25% sodium hypochlorite solutions modified with surfactants, Hypoclean A and Hypoclean B, had surface tension values that were significantly lower (P < 0.01) than Chlor-Xtra and 5.25% NaOCl. Because of their low surface tension and increased contact with dentinal walls, these new irrigants have the potential to penetrate more readily into uninstrumented areas of root canal system as well as allow a more rapid exchange with fresh solution, enabling greater antimicrobial effectiveness and enhanced pulp tissue dissolution ability

In vivo and in vitro permeability of one-step self-etch adhesives

Adhesive dentistry should effectively restore the peripheral seal of dentin after enamel removal. We hypothesize that non-rinsing, simplified, one-step self-etch adhesives are effective for minimizing dentin permeability after tooth preparation procedures. Crown preparations in vital human teeth were sealed with Adper Prompt, Xeno III, iBond, or One-Up Bond F. Epoxy resin replicas were produced from polyvinyl siloxane impressions for SEM examination. Dentin surfaces from extracted human teeth were bonded with these adhesives and connected to a fluid-transport model for permeability measurements and TEM examination. Dentinal fluid droplets were observed from adhesive surfaces in resin replicas of in vivo specimens. In vitro fluid conductance of dentin bonded with one-step self-etch adhesives was either similar to or greater than that of smear-layer-covered dentin. TEM revealed water trees within the adhesives that facilitate water movement across the polymerized, highly permeable adhesives. Both in vitro and in vivo results did not support the proposed hypothesis.published_or_final_versio