Endodontic treatment of chronic apical periodontitis ameliorates systemic inflammation and restores impaired cellular responses to insulin in an in vitro model.

INTRODUCTION: A growing body of research supports an association between periapical inflammation and an increased risk of developing systemic diseases. There is currently no scientific evidence to support a causal effect of inflammation on the onset of insulin resistance (IR) in patients with apical periodontitis (AP). The aim of this in vitro study was to evaluate any association between AP and levels of serum inflammatory factors potentially associated with the onset of IR, and to investigate any the effect of root canal treatment (RCT) on these systemic inflammation markers and restoring on the response in vitro to insulin. METHODS: A total of 27 control subjects and 27 patients with AP were enrolled. Patients with AP underwent RCT and were followed-up 6 and 12 months post-treatment. ELISAs were used to evaluate plasma serum levels of pro-inflammatory cytokines interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor (TNF)-α. The human pancreatic epithelioid carcinoma cell line (PANC-1) was used to assess t The response in vitro to insulin was assessed by measuring glucose consumption in a human pancreatic epithelioid carcinoma cell line (PANC-1) treated with sera from healthy and AP subjects. RESULTS: At baseline AP was associated with significantly higher levels of IL-1, IL-6, and IL-8 in the serum of untreated (AP) patients with AP vs controls (p<0.001). Glucose consumption decreased in pancreatic cells incubated with baseline serum from patients with AP, in a manner proportional to total cytokines amount. Notably, endodontic treatment was associated with reduced levels of cytokines (p<0.001) and improved response to insulin in AP group (p<0.001). CONCLUSIONS: Our findings suggest that AP may promote inflammatory-driven IR in an in-vitro model, and that RCT may ameliorate inflammatory mediators in vivo and the cellular response to insulin in vitro.

Endodontic microsurgery virtual reality simulation and digital workflow process in a teaching environment.

INTRODUCTION: Computer simulations are stimulating increased attention in dentistry. Augmented reality superimposes a virtual scenario over an existing reality and allows interaction with it. Virtual reality (VR) simulates a fully immersive situation permitting the user to experience the full environment in real time. Haptic technology provides tactile and realistic force feedback for the user to experience the immersive situation as if they were really there. Preclinical training is important to gain familiarity with difficult surgical techniques and to implement interpersonal skills. Developing a valid assessment of surgical simulation is challenging. This paper wants to present a newly realized VR simulation in endodontic microsurgery through the developmental digital workflow, the demonstration of a haptic VR scenario and student self-assessment and self-reflection feedback. METHODS: The volumes were exported in a stereolithography format to prepare and optimize in terms of shape and shade for the VR simulation. The graphics and touchable haptic solid were created using Virteasy Editor, which allows the transformation of 3D surfaces into graphical and volumetric haptic solids depending on their material (enamel, dentine, pulp and bone). Users were asked to execute the osteotomy and root-resection preparation. The assessment criteria were determined, and the feedback statements were created by a questionnaire with fixed answers. Objective and qualitative criteria for assessing the preparation were obtained from the literature. RESULTS: This study provides proof that it is possible to provide reliable and clinically relevant qualitative feedback with a VR simulator. CONCLUSION: VR simulation offers an innovative approach with all the benefits of clinical experience. It permits you to save your own progress and review the assessment at any time.

Dynamic Navigation System vs. Free-Hand Approach in Microsurgical and Non-Surgical Endodontics: A Systematic Review and Meta-Analysis of Experimental Studies.

(1) Background: A Dynamic Navigation System (DNS) is an innovative tool that facilitates the management of complex endodontic cases. Despite the number of advantages and limitations of this approach, there is no evidence-based information about its efficiency in comparison with that of the traditional method in endodontics. (2) Objectives: We aimed to explore any beneficial effects of the DNS and compare the outcomes of DNS vs. free-hand (FH) approaches for non-surgical and microsurgical endodontics. (3) Methods: A literature search was conducted in August 2023 to identify randomized, experimental, non-surgical, and microsurgical endodontic studies that compared the DNS with FH approaches. The procedural time (ΔT, s), substance loss (ΔV, mm3), angular deviation (ΔAD, °), coronal/platform linear deviation (ΔLD_C, mm), and apical linear deviation (ΔLD_A, mm) were recorded and analyzed. Quality and risk of bias assessments were conducted according to the Quality Assessment Tool For In Vitro Studies. A meta-analysis was performed using mean difference and standard deviation for each outcome, and heterogeneity (I2) was estimated. p < 0.05 was considered significant. (4) Results: One-hundred and forty-six studies were identified following duplicate removal, and nine were included in the systematic review and meta-analysis. The overall risk of bias was classified as low. The DNS was found to be more accurate and efficient than the FH approach was, resulting in a significantly shorter operation time (p < 0.00001) and less angular (p ≤ 0.0001) and linear deviation (p ≤ 0.01). For substance loss, the advantage of the DNS was significant only for microsurgery (p = 0.65, and p < 0.005, for non-surgical and microsurgical procedures, respectively). A reduced risk of iatrogenic failure using the DNS was observed for both expert and novice operators. (5) Conclusions: The DNS appears beneficial for non-surgical and microsurgical endodontics, regardless of the operator's experience. However, appropriate training and experience are necessary to access the full advantages offered by the DNS.

Does Curing Delay Affect the Bond Strength of Fiber Post with Self-Adhesive Cements?

PURPOSE: To evaluate the effect of three different curing protocols based on different ratios of self-curing and light-curing periods on the bond strength and nanoleakage of fiber posts luted with dual-curing self-adhesive cements. MATERIALS AND METHODS: A total of 48 single-root teeth were endodontically treated and obturated, and an 8-mm post space was prepared with dedicated drills. Specimens were randomly divided into two groups according to the self-adhesive cement employed: group 1 (G1) = PANAVIA SA Plus (Kuraray Noritake), and group 2 (G2) = Bifix SE (VOCO). The specimens were further divided into three subgroups (n = 8 each) according to the light-curing protocol applied: no light-curing (SG1), 20 seconds of light-curing 20 seconds after cement injection (SG2), and 20 seconds of light-curing 120 seconds after cement injection (SG3). Slices of 1-mm thickness were prepared for the pushout test and nanoleakage analyses of the coronal and apical regions after 24 hours of storage in artificial saliva. Results were statistically analyzed with three-way ANOVA and Tukey post hoc tests. Statistical significance was set for P < .05. RESULTS: Three-way ANOVA analysis showed that the factors of cement (P = .02) and curing protocol (P < .001) had a significant influence on bond strength. Tukey post hoc test reported that light-curing 120 seconds after injection showed higher bond strength compared to both no light-curing and photoactivation after 20 seconds. CONCLUSION: To achieve the highest bond strength with self-adhesive cements, photoactivation with a 120-second delay after mixing is required. There is no difference between light-curing immediately and light-curing 20 seconds after mixing.

Working length variation during multiple-visit endodontic treatment: An observational study.

This study investigated variation in working length during multiple-visit endodontic treatment. Patients (N = 106) with pulpitis or pulp necrosis, with or without apical periodontitis, were included. During the first appointment, glide path was performed with ProGlider and shaping with ProTaper Next. Working length was detected four times. Working length was then re-recorded prior to filling during the second appointment and a 0.5 mm threshold was selected as the minimum clinically meaningful variation. A logistic regression model was used to evaluate the impact of tooth anatomy, preoperative pulp status, apical periodontitis and lesions of endodontic origin on working length variation. Working length varied between first and second appointments in 34% of patients. The presence of apical periodontitis was the only variable significantly associated with variation in working length (p = 0.011). These data suggest that working length should be re-checked prior to root canal filling to prevent procedural errors.

Micro-computed tomographic evaluation of endodontic ledge position in relation to canal curvatures.

BACKGROUND: Endodontic ledge (EL) formation is the most common complication of endodontic treatment. Although various etiological factors have been identified, canal curvature is the most significant variable correlated with EL formation. The aim of this micro-computed tomographic (micro-CT) study was to evaluate EL position in the mesial canals of the lower molars in relation to the degree of canal curvature. METHODS: Forty intact mandibular first molars with independent mesial canals with 20°-40° primary mesio-distal curvature, 10°-30° buccal-lingual canal curvature and 4 < r ≤ 8 mm main curvature radius were selected. Working length was measured with a K-File #10 and a high resolution pre-operative micro-CT analysis was performed. Ledges were created at the point of maximum canal curvature using stainless steel K-Files #30-35, alternating irrigation with 5% NaOCl and 10% EDTA. A post-operative high-resolution micro-CT analysis was then completed. Pre- and post-operative images were analyzed. The angle (α) formed between the vector passing through the geometric center of the EL and the center of the original canal lumen and the line joining the centers of the mesio-buccal and mesio-lingual canal orifices was calculated, and a descriptive statistical analysis was achieved. The α angle values were analyzed in relation to canal curvature using Kruskal-Wallis and post hoc Dunn's tests. The level of significance was set at P < 0.05. RESULTS: The α angles appeared inversely proportional to canal curvatures in the buccal-lingual and mesio-distal projections. The mean α angle was 36.4° (standard deviation 10.64; 95% confidence interval 34.1-40.9). CONCLUSION: Within the limitations of this study, endodontic ledges develop in the opposite direction to the three-dimensional canal curvature and their position is influenced by the degree of curvature. Clinically, the α angle values may be related to the recommended direction to manage endodontic ledges.

Micro-Computed Tomography Evaluation of Minimally Invasive Shaping Systems in Mandibular First Molars.

The aim of this study was to compare the shaping ability of a modified ProTaper Next technique (PTNm) with that of TruNatomy (TN) in lower molars mesial curved canals using micro-computed tomography (Micro-CT). Sixty mesial canals of first mandibular molars were randomly assigned between two groups (n = 30). After canal scouting with K-File #10, glide path and shaping were carried out with TN or PTNm systems. The PTNm sequence consists of ProGlider, followed by ProTaper Next X1 and apical finishing with NiTiFlex #25 up to working length (WL) to ensure adequate apical cleaning. Samples were scanned using micro-CT and pre- and post-shaping volumes were matched to analyse geometric parameters: the volume of removed dentin; the difference of canal surface; centroid shift, minimum and maximum root canal diameters; cross-sectional areas; the ratio of diameter ratios (RDR) and the ratio of cross-sectional areas (RA). Measurements were assessed 2 mm from the apex and in relation to the middle and coronal root canal thirds. Data were analysed using ANOVA (p < 0.05). No statistically significant differences were found between the groups for any parameter at each level of analysis, except for RA at the coronal level (p = 0.037). The PTNm system showed the tendency to enlarge more in the coronal portion with a lower centroid shift at apical level compared with TN sequence (p > 0.05). Both PTNm and TN sequences demonstrated similar maintenance of original anatomy during the shaping of lower molar mesial curved canals.

Wear Behaviour of Polymer-Infiltrated Network Ceramics, Lithium Disilicate and Cubic Zirconia against Enamel in a Bruxism-Simulated Scenario.

The present study aimed to evaluate the wear rate of polymer-infiltrated network composites and ceramics against enamel in a bruxism-simulated scenario. Ninety-six (n = 96) molars were divided into six groups (n = 16) according to their occlusal material: group 1-a polymer-infiltrated network ceramic (PINC); group 2-a second polymer-infiltrated network ceramic (PINC2); group 3-nanohybrid resin-based composite (CO); group 4-cubic zirconia (ZR); group 5-lithium disilicate (LS); and group 6-sound enamel (EN). A laser scanner was used to digitalize all of the occlusal surfaces before and after a fatigue test, which was conducted with a chewing simulator set at 80 N and semicircular movement in order to simulate bruxist movement and loads. Statistical analysis of volume loss was performed with a one-way ANOVA and post hoc Bonferroni test. ZR had significantly inferior wear to PINC (p ≤ 0.01) and CO (p = 0.04). LS wore the antagonist enamel significantly more than PINC, CO, PINC2 and EN (p ≤ 0.01). On the other hand, ZR wore the antagonist enamel significantly more than CO (p ≤ 0.01) and PINC2 (p = 0.05). In conclusion, PINCs better preserved antagonist enamel at the expense of a higher wear of their own. LS causes significantly higher enamel wear compared with PINCs. ZR caused significantly higher enamel wear compared with CO and PINC2, but it was wear-resistant.

Confocal Laser Scanner Evaluation of Bactericidal Effect of Chitosan Nanodroplets Loaded with Benzalkonium Chloride.

The aim was to evaluate the antibacterial efficacy and penetration depth into dentinal tubules of a solution of chitosan nanodroplets (NDs) loaded with Benzalkonium Chloride (BAK). Seventy-two human single-root teeth with fully formed apex were used. Cylindrical root dentin blocks were longitudinally sectioned and enlarged to a size of a Gates Glidden drill #4. After sterilization, root canals were infected with Enterococcus faecalis ATCC 29212 and further incubated for three weeks. Specimens were assigned to three experimental groups (n = 20), plus positive (n = 6) and negative (n = 6) controls. In the first group, irrigation was achieved with 2 mL of NDs solution loaded with BAK (NDs-BAK), in the second with 2 mL of 5% sodium hypochlorite (NaOCl) and in the last with 2 mL of 2% chlorhexidine (CHX). Specimens were rinsed and vertically fractured. Confocal laser scanning microscopy (CLSM) and viability staining were used to analyze the proportions of dead and live bacteria quantitatively. The volume ratio of red fluorescence (dead) was calculated in 3D reconstructions. Data were analyzed by one-way ANOVA and post hoc Bonferroni tests (p < 0.05). The ratio of red fluorescence over the whole green/red fluorescence resulted in a significant comparison of NDs-BAK with NaOCl (p < 0.01) and NaOCl with CHX (p < 0.01). No differences were found between NDs-BAK and CHX (p > 0.05). The mean depth of efficacy was, respectively: NDs-BAK 325.25 µm, NaOCl 273.36 µm and CHX 246.78 µm with no statistical differences between groups. The NaOCl solution showed the highest antimicrobial efficacy, but nanodroplets with BAK seemed to have the same effect as CHX with a high depth of efficacy.

Micro-CT evaluation of rotary and reciprocating glide path and shaping systems outcomes in maxillary molar curved canals.

The shaping outcomes after instrumentation with rotary and reciprocating glide path and shaping systems were evaluated through micro-computed tomography (Micro-CT). Thirty extracted maxillary first molars were selected. Mesio-buccal canals were randomized into two groups (n = 15): rotary system ProGlider and ProTaper Next X1, X2 (PG-PTN) and reciprocating system WaveOne Gold Glider and WaveOne Gold Primary (WOGG-WOG). Specimens were micro-CT scanned before, after glide path and after shaping. Increase in canal volume and surface area, percentage of removed dentin from the inner curvature, centroid shift and canal geometry variation through ratio of diameter ratios (RDR) and ratio of cross-sectional areas (RA) were measured in the apical and coronal levels and at the point of maximum curvature. The number of pecking motions needed to reach the working length (WL) was recorded. One-way ANOVA and post hoc Turkey-Kramer tests were used (p < 0.05). Post-glide path analysis revealed that in the coronal third, RDR was more favorable to PG and centroid shift was lower for WOGG in the apical third. Post-shaping analysis showed a reduced removal of dentin and a more favorable RA for PTN at point of maximum curvature. The number of pecking motions up to WL resulted in different between groups both for glide path and shaping phases. Despite a higher dentin removal for reciprocating instruments at the point of maximum curvature, both systems seemed to produce well-centered glide path and shaping outcomes. Rotary and reciprocating systems seemed able to respect the original canal anatomy.

Postoperative Pain following Root Canal Filling with Bioceramic vs. Traditional Filling Techniques: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

This meta-analysis aimed to evaluate postoperative pain (POP) following root canal filling (RCF) with gutta-percha/bioceramic sealer (BCS) vs. gutta-percha/traditional sealer (TS) techniques. Electronic databases were searched for randomized trials. Subgroup analyses were performed for analgesic intake, flare-ups, postoperative time (24/48 h), pulp status, and retreatment. The search yielded 682 records, and nine studies were selected. BCS was associated with significantly lower POP vs. TS at 24 h (P = 0.04) and 48 h (P = 0.0005). In addition, non-significant trends favoring BCS for analgesic intake at 24 h (P = 0.14), flare-ups (P = 0.24) and obturation techniques at 24 h (P = 0.41) and 48 h (P = 0.33), non-significant trends for lower POP with TS vs. BCS 24 h and 48 h in vital teeth (P = 0.50, P = 0.18, respectively), and for lower POP with BCS vs. TS in non-vital teeth at 24 h and 48 h (P = 0.16, P = 0.84, respectively). POP was numerically lower with TS vs. BCS at 24 h (P = 0.65) and 48 h after retreatment (P = 0.59). Moreover, POP did not vary between fillers when the treatment was over single (P = 0.28) or multiple visits (P = 0.50). BCS was associated with significantly lower short-term POP, and with a trend for lower analgesic intake and flare-up incidence, as compared to TS.

Influence of Photon-Induced Photoacoustic Streaming (PIPS) on Root Canal Disinfection and Post-Operative Pain: A Randomized Clinical Trial.

The aim of this study was to evaluate the ability of a PIPS (photon-induced photoacoustic streaming) Er:YAG laser to reduce the root canal system bacterial count in vivo in comparison to the traditional irrigation technique. The post-operative patients' quality of life (QoL) after endodontic therapy was evaluated through a questionnaire. Fifty-four patients affected by pulp necrosis with or without apical periodontitis biofilm disease were selected for endodontic treatment and randomly assigned to Group A (n = 27) with traditional irrigation and Group B (n = 27), with PIPS irrigation applied according to the protocol. Shaping was performed with ProGlider and ProTaper Next, and irrigation was performed with 5% NaOCl and 10% EDTA. Intracanal samples for culture tests were collected before and after irrigation. The microbiological analysis was evaluated by the Kolmogorov-Smirnov normality and Mann-Whitney tests (p < 0.05). A self-assessment questionnaire was used to evaluate the QoL during the 7 days after treatment; differences were analysed with Student's t-test. Irrigation with the PIPS device was significantly effective in reducing bacterial counts, which were higher for facultative than obligate anaerobic strains, particularly for Gram-negative bacteria, without statistical significance (p > 0.05). There were no significant differences among the QoL indicators, except for the maximum pain (p = 0.02), eating difficulty (p = 0.03) and difficulty performing daily functions (p = 0.02) in the first few days post-treatment. PIPS may represent an aid to root canal disinfection not affecting the patients' QoL, particularly for the first day after treatment.

Endothelial Dysfunction Marker Variation in Young Adults with Chronic Apical Periodontitis before and after Endodontic Treatment.

INTRODUCTION: Cardiovascular diseases are the leading cause of mortality worldwide. Apical periodontitis (AP) has been associated with an increased risk of cardiovascular diseases. A correlation has been shown between chronic AP and endothelial dysfunction (ED), but there is no evidence to indicate ED improves after endodontic treatment in patients with periapical lesions. The aim of this study was to investigate vascular and molecular markers of early ED before and after root canal treatment in young adults with chronic AP. METHODS: Twenty control subjects and 21 patients with AP were assessed at baseline. The AP patients were also evaluated 2 and 12 months post-treatment. Endothelial flow reserve was assessed via an endothelial function test, and enzyme-linked immunosorbent assays were used to evaluate plasma levels of proinflammatory cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor alpha; vasoconstrictor ED marker endothelin (ET)-1; circulating endothelial adhesion markers intercellular adhesion molecule 1 (ICAM-1)/CD54 and soluble vascular cellular adhesion molecule (sVCAM)-1/CD106; soluble CD14; and the endothelial leukocyte adhesion molecule (E-selectin). RESULTS: AP was associated with increased serum levels of ET-1, ICAM-1, E-selectin, IL-1, and sCD14, suggesting early vascular ED, with no macroscopic evidence of a reduction in endothelial flow reserve. Root canal treatment ameliorated inflammation and early ED, lowering plasma levels of IL-1, sCD14, ET-1, ICAM-1/CD54, and E-selectin to those of control subjects. CONCLUSIONS: Our findings suggest that AP may drive early vascular ED and that the endodontic therapy of AP ameliorates early ED.

Influence of surface coating sealer on resin composite water absorption and discoloration: An in vitro study.

PURPOSE: To evaluate the in vitro efficacy of surface coating sealer (SCS) in reducing the amount of water absorption and stain formation in resin composites. METHODS: To evaluate the amount of water sorption, 40 stainless steel round molds (n=10 per composite) were filled with Filtek Supreme XTE; Venus Diamond; Clearfil Majesty ES-2; Gradia Direct Anterior. Groups were further divided into two subgroups (n=5) according to the presence/absence of SCS (Easy Glaze). Their masses were measured at baseline and reweighed at 1, 4, 12, and 20 weeks. For staining evaluation, 48 resin composite discs, 2 mm-thick, were obtained with the same composites and SCS was applied on a single surface of each sample. After baseline color assessment, samples were immersed in vials containing 5 mL of six different staining solutions. Color evaluation was performed again after 1, 4, 12, and 20 weeks. Three-way ANOVA was performed to evaluate differences in weight gain and color changes (P< 0.05). RESULTS: A significant protective action of SCS (P< 0.001), but not of the composites (P= 0.366) was found. Differences in weight and color change were not influenced by the resin composite, but only by the presence of the coating on the surface of the samples. SCS are well-established materials for polishing and protecting composite restorations from water sorption and color changes. Different staining solutions can still produce different effects on resin composite. CLINICAL SIGNIFICANCE: Surface coating sealers are able to reduce water uptake and discoloration from resin composites, thus leading to less degradation of composite restorations over time.

Influence of Contracted Endodontic Access on Root Canal Geometry: An In Vitro Study.

INTRODUCTION: Contracted endodontic cavities (CECs) have developed from the concept of minimally invasive dentistry and provide an alternative to traditional endodontic cavities (TECs). They have been designed in an effort to preserve the mechanical stability of teeth. The contracted cavity design preserves more of the dentin but may influence the geometric shaping parameters. The aim of this micro-computed tomographic study was to evaluate the influence of contracted endodontic cavities on the preservation of the original root canal anatomy after shaping with nickel-titanium rotary instruments. METHODS: Thirty extracted human mandibular molars with fully formed apices and independent mesial canals were randomly assigned to group 1 (TEC) and group 2 (CEC). Each group was shaped using ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer). Irrigation was performed with 10% EDTA and 5% sodium hypochlorite. Samples were scanned before and after canal shaping to match canal volumes (SkyScan; Bruker microCT, Kontich, Belgium [100 kV, 100 µA, and 15-µm resolution]), and images were analyzed to evaluate canal volumes, surface areas, and centroid shift on cross sections at -1 mm and -3 mm from the apex. RESULTS: TECs showed a greater preservation of the original root canal anatomy with less apical transportation than CECs, possibly because of the absence of coronal interferences and, therefore, fewer pecking motions required to complete instrumentation. CONCLUSIONS: Within the limitations of this study, TECs may lead to a better preservation of the original canal anatomy during shaping compared with CECs, particularly at the apical level.

Influence of Operator's Experience on the Shaping Ability of Protaper Universal and Waveone Systems: A Comparative Study on Simulated Root Canals.

OBJECTIVE: To assess the influence of operator experience on: shaping and centering ability, mean preparation time and presence of canal aberrations of ProTaper Universal and WaveOne systems on simulated root canals. MATERIALS AND METHODS: Sixty S-shaped canals in resin blocks were assigned to four groups (n=15 for each group). Group1 (Experienced operator, ProTaper), Group2 (Experienced operator, WaveOne), Group3 (Inexperienced operator, ProTaper), Group4 (Inexperienced operator, WaveOne). Photographic method was used to record pre- and post-instrumentations images. After superimposition, it has been evaluated presence of canal aberrations and differences in shaping and centering ability between groups. RESULTS: WaveOne system produced a lower amount of canal aberrations both in the hand of expert than inexpert operators. However, a WaveOne instrument breakage occurred in the hands of an inexperienced operator. No differences have been found in the evaluation of shaping ability with both systematics. Operator's experience doesn't influence the shaping ability of ProTaper and WaveOne systems. CONCLUSION: Experience factor could influence the centering ability in the use of both the systematics. However, WaveOne Primary reduce the mean preparation time and the presence of canal aberrations.

Effects of fiber-glass-reinforced composite restorations on fracture resistance and failure mode of endodontically treated molars.

OBJECTIVES: The study evaluated the fracture resistance and fracture patterns of endodontically treated mandibular first molars restored with glass-fiber-reinforced direct composite restorations. METHODS: In total, 60 extracted intact first molars were treated endodontically; a mesio-occluso-distal (MOD) cavity was prepared and specimens were then divided into six groups: sound teeth (G1), no restoration (G2), direct composite restoration (G3), fiber-post-supported direct composite restoration (G4), direct composite reinforced with horizontal mesio-distal glass-fibers (G5), and buccal-palatal glass-fibers (G6). Specimens were subjected to 5000 thermocycles and 20,000 cycles of 45° oblique loading force at 1.3Hz and 50N; they were then loaded until fracture. The maximum fracture loads were recorded in Newtons (N) and data were analyzed with one-way ANOVA and post-hoc Tukey tests (p<0.05). Fractured specimens were analyzed with a scanning electron microscope (SEM). RESULTS: The mean static loads (in Newtons) were: G1, 831.83; G2, 282.86; G3, 364.18; G4, 502.93; G5, 499.26; and G6, 582.22. Fracture resistance did not differ among G4, G5, and G6, but was significantly higher than G3 (p=0.001). All specimens fractured in a catastrophic way. In G6, glass fibers inducted a partial deflection of the fracture, although they were not able to stop crack propagation. CONCLUSIONS: For the direct restoration of endodontically treated molars, reinforcement of composite resins with glass-fibers or fiber posts can enhance fracture resistance. The SEM analysis showed a low ability of horizontal glass-fibers to deviate the fracture, but this effect was not sufficient to lead to more favorable fracture patterns above the cement-enamel junction (CEJ). CLINICAL SIGNIFICANCE: The fracture resistance of endodontically treated molars restored with direct composite restorations seems to be increased by reinforcement with fibers, even if it is insufficient to restore sound molar fracture resistance and cannot avoid vertical fractures.

Influence of dentin pretreatment with synthetic hydroxyapatite application on the bond strength of fiber posts luted with 10-methacryloyloxydecyl dihydrogen phosphate-containing luting systems.

The aim of this in vitro study was evaluate the effect of application of synthetic hydroxyapatite on fiber post bond strength to radicular dentine. Forty, single-root teeth were endodontically treated and an 8 mm post space was prepared. Specimens were randomly placed in four groups (n = 10 in each) and treated using the following fiber post luting procedures: group 1, 17% EDTA + Panavia SA; group 2, 17% EDTA + Teethmate Desensitizer + Panavia SA; group 3, All-Bond Universal + Duo-Link Universal; and group 4, All-Bond Universal + Teethmate Desensitizer + Duo-Link Universal. Fiber posts were luted in the post space and light-cured for 120 s using a light-emitting diode (LED) lamp. After 7 d of storage at 37°C, the teeth were cut into 1-mm-thick slices, which were subjected to a push-out test until failure using a universal testing machine. Two specimens per group were prepared for scanning electron microscopy analysis. An energy-dispersive X-ray spectroscopy detector was used for elemental analysis of the specimen surface. The results were statistically analyzed using one-way anova. The fiber post bond strength was statistically significantly increased after the application of Teethmate Desensitizer to post space walls, either with a 10-MDP-containing self-adhesive cement or with a universal adhesive. Scanning electron microscopy and EDAX analysis showed that Teethmate Desensitizer created a calcium phosphate precipitate over post space dentinal tubules, which significantly improved the bond strength of the fiber post luted with 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing adhesive systems.

Influence of operator experience on non-carious cervical lesion restorations: Clinical evaluation with different adhesive systems.

PURPOSE: To evaluate the influence of operator experience on adhesive technique and to assess the clinical performances of two different adhesive systems. METHODS: 90 cervical lesions in 42 subjects, with a mean age of 52.4 years (range between 32-63) were selected. Lesions were divided into two groups according to operator experience (n = 42 restorations performed by a skilled operator, n = 48 restorations performed by five unexperienced operators) and further divided into two subgroups according to the adhesive system used: three-step etch-and-rinse (Optibond FL) or one step self-etch (G-Bond). Adhesives were applied according to manufacturers' instructions. Subjects underwent follow-up at 12, 24, and 36 months and restoration retention, enamel and dentin marginal integrity, marginal discoloration, caries occurrence, post-operative sensitivity, and preservation of tooth vitality were evaluated according to USPSH criteria. ANOVA test was performed to evaluate the influence of the adhesive system, the operator experience, and aging on restorations. RESULTS: Operator experience (expert vs. inexperienced), aging time (12, 24, or 36 months), and the adhesive system (self-etch vs. etch-and-rinse) all affected the results statistically, as did the interaction between the adhesive system and operator experience.