Micro-CT evaluation of several glide path techniques and ProTaper Next shaping outcomes in maxillary first molar curved canals.

AIM: To evaluate the ability of ProGlider instruments, PathFiles and K-files to maintain canal anatomy during glide path preparation using X-ray computed micro-tomography (micro-CT). METHODOLOGY: Forty-five extracted maxillary first permanent molars were selected. Mesio-buccal canals were randomly assigned (n = 15) to manual K-file, PathFile or ProGlider groups for glide path preparation. Irrigation was achieved with 5% NaOCl and 10% EDTA. After glide path preparation, each canal was shaped with ProTaper Next X1 and X2 to working length. Specimens were scanned (isotropic voxel size 9.1 µm) for matching volumes and surface areas and post-treatment analyses. Canal volume, surface area, centroid shift, canal geometry variation through ratio of diameter ratios and ratio of cross-sectional areas were assessed in the apical and coronal levels and at the point of maximum canal curvature. One-way factorial anovas were used to evaluate the significance of instrument in the various canal regions. RESULTS: Post-glide path analysis revealed that instrument factor was significant at the apical level for both the ratio of diameter ratios and the ratio of cross-sectional areas (P < 0.001), with an improved maintenance of root canal geometry by ProGlider and PathFile. At the coronal level and point of maximum canal curvature, ProGlider demonstrated a tendency to pre-flare the root canal compared with K-file and PathFile. PathFile and ProGlider demonstrated a significantly lower centroid shift compared with K-file at the apical level (P = 0.023). Post-shaping analysis demonstrated a more centred preparation of ProGlider, compared with PathFile and K-files, with no significant differences for other parameters. CONCLUSIONS: Use of ProGlider instruments led to less canal transportation than PathFiles and K-files.

Postoperative quality of life following single-visit root canal treatment performed by rotary or reciprocating instrumentation: a randomized clinical trial.

AIM: To compare the impact of rotary and reciprocating instrumentation on postoperative quality of life (POQoL) after single-visit primary root canal treatment. METHODOLOGY: A randomized controlled clinical trial was designed and carried out in a University endodontic practice in northern Italy. Healthy subjects with asymptomatic irreversible pulpitis, symptomatic irreversible pulpitis or pulp necrosis with or without apical periodontitis (symptomatic or asymptomatic) scheduled for primary root canal treatment were enrolled. Single-visit root canal treatment was performed with ProTaper™ S1-S2-F1-F2 (rotary group, n = 23) and WaveOne™ Primary (reciprocating group, n = 24). Irrigation was performed with 5% NaOCl and 10% EDTA. Root canal filling was performed with the continuous-wave technique and ZOE sealer. POQoL indicators were evaluated for 7 days post-treatment. The variation of each indicator over time was compared using anova for repeated measures (P < 0.05). The impact of each variable on POQoL was analysed with a multivariate logistic regression model (P < 0.05). RESULTS: Pain curves demonstrated a more favourable time-trend in the rotary group (mean, P = 0.077; maximum, P = 0.015). Difficulty in eating (P = 0.017), in performing daily activities (P = 0.023), in sleeping (P = 0.021) and in social relations (P = 0.077), was more evident in the reciprocating group. Patients' perception of the impact of treatment on POQoL was more favourable in the rotary group (P = 0.006). Multirooted tooth type and pre-existing periradicular inflammation were associated with a decrease in POQoL. CONCLUSION: Reciprocating instrumentation affected POQoL to a greater extent than rotary instrumentation.

The HIV-1 Pr55 gag polyprotein binds to plastidial membranes and leads to severe impairment of chloroplast biogenesis and seedling lethality in transplastomic tobacco plants.

Chloroplast genetic engineering has long been recognised as a powerful technology to produce recombinant proteins. To date, however, little attention has been given to the causes of pleiotropic effects reported, in some cases, as consequence of the expression of foreign proteins in transgenic plastids. In this study, we investigated the phenotypic alterations observed in transplastomic tobacco plants accumulating the Pr55(gag) polyprotein of human immunodeficiency virus (HIV-1). The expression of Pr55(gag) at high levels in the tobacco plastome leads to a lethal phenotype of seedlings grown in soil, severe impairment of plastid development and photosynthetic activity, with chloroplasts largely resembling undeveloped proplastids. These alterations are associated to the binding of Pr55(gag) to thylakoids. During particle assembly in HIV-1 infected human cells, the binding of Pr55(gag) to a specific lipid [phosphatidylinositol-(4-5) bisphosphate] in the plasma membrane is mediated by myristoylation at the amino-terminus and the so-called highly basic region (HBR). Surprisingly, the non-myristoylated Pr55(gag) expressed in tobacco plastids was likely able, through the HBR motif, to bind to nonphosphorous glycerogalactolipids or other classes of lipids present in plastidial membranes. Although secondary consequences of disturbed chloroplast biogenesis on expression of nuclear-encoded plastid proteins cannot be ruled out, results of proteomic analyses suggest that their altered accumulation could be due to retrograde control in which chloroplasts relay their status to the nucleus for fine-tuning of gene expression.

Hands-on experiments on glycemia regulation and type 1 diabetes.

In the present article, we describe a 3-day experimental workshop on glycemia regulation and type 1 diabetes that engages students in open-ended investigations and guided experiments leading to results that are not already known to them. After an initial questioning phase during which students observe PowerPoint slides depicting the glycemia (blood glucose levels) of individuals in various situations, students design, execute, and interpret experiments to address one of the following questions: 1) Which criteria must an animal model of diabetes fulfill? 2) How do pancreatic cells maintain glycemia constant? and 3) Is there a way to produce an insulin protein similar to the one released by human pancreatic cells? Students then 1) measure glycemia and glycosuria in control mice and in a mouse model of type 1 diabetes (Alloxan-treated mice), 2) measure the release of insulin by pancreatic ß-cells (INS-1 cell line) in response to different concentrations of glucose in the extracellular medium, and 3) transfect Chinese hamster ovary cells with a plasmid coding for green fluorescent protein, observe green fluorescent protein fluorescence of some of the transfected Chinese hamster ovary cells under the microscope, and observe the characteristics of human insulin protein and its three-dimensional conformation using RASMOL software. At the end of the experimental session, students make posters and present their work to researchers. Back at school, they may also present their work to their colleagues.

A multidisciplinary guided practical on type I diabetes engaging students in inquiry-based learning.

In the present article, we describe a 3-day experimental workshop on type I diabetes aimed at helping high school students to understand how fundamental research on glycemia regulation contributes to the development of scientific knowledge and therapeutic strategies. The workshop engaged students in open-ended investigations and guided experiments. Each class was divided into three or four groups, with each group working with a trained doctoral student or postdoctoral fellow. During an initial questioning phase, students observed slides depicting the glycemia of individuals in various situations. Students identified hyperglycemic individuals relative to the average glycemia of the displayed population. Students were asked to devise a treatment for these diabetics. They quickly realized that they couldn't experiment on patients and understood the need for laboratory models. Each group gave ideas of experiments to perform. We then explained, taking into account their propositions, the protocols students could execute to address one of the following questions: Which criteria must an animal model of diabetes fulfill? How do pancreatic cells maintain glycemia? Is there a way to produce an insulin protein similar to the one released by human pancreatic cells? We used two different evaluation metrics of the workshop: a questionnaire filled out by the students before and after the workshop and a poster produced by students at the end of the workshop. We found that this educational approach successfully improved student awareness and understanding of the scientific reasoning and research process.

Transgene-induced pleiotropic effects in transplastomic plants.

Since the first demonstration of stable transgene integration in the plastid genome (plastome) of higher plants, plastid transformation has been used for a wide range of purposes, including basic studies as well as biotechnological applications, showing that transplastomic plants are an effective system to produce recombinant proteins. Compared to nuclear transformation, the main advantages of this technology are the high and stable production level of proteins as well as the natural containment of transgenes. To date, more than 100 transgenes have been successfully expressed in plant chloroplasts. In some cases, however, unintended pleiotropic effects on plant growth and physiology were shown in transplastomic plants. In this paper, we review such effects and discuss some of the technologies developed to overcome them.

Fibre post adaptation and bond strength in oval canals.

AIM: To evaluate ex vivo the bond strength and adaptation of fibre posts with oval and circular cross sections luted in oval canals with post spaces prepared using dedicated drills or ultrasonic tips. METHODOLOGY: Forty extracted premolars with oval canals were root filled, then randomly divided into four groups according to the post space preparation device and the shape of the luted fibre post: dedicated drill + round post, dedicated drill + oval post, ultrasonic tip + round post and ultrasonic tip + oval post. Posts were cemented with a self-adhesive cement (RelyX Unicem 2; 3M ESPE). Samples were sectioned in 1-mm-thick slices and observed under a microscope, and the area occupied by the post within the post space area was calculated. Bond strength was then measured using a push-out test, and the failure modes were evaluated with a stereomicroscope at 40× magnification. Fibre post adaptation and push-out test results were evaluated by analysis of variance (P < 0.05). RESULTS: Fibre posts, both round and oval, were better adapted to the apical region of the post space (P = 0.001). In oval canals, the bond strength was significantly higher in coronal regions, when the post space was prepared with a dedicated drill and an oval post was luted (P < 0.0001). Adhesive failures between cement and post were the most frequent type of failure in all groups. CONCLUSIONS: Circular and oval posts achieved similar adaptation to oval canals, but the use of ultrasonic tips and round posts resulted in reduced bond strength values.

Active application of liquid etching agent improves adhesion of fibre posts to intraradicular dentine.

AIM: To assess the effectiveness of an active application of liquid etching, compared with the standard gel formulation on smear layer removal from post space walls and push-out bond strength of luted fibre posts. METHODOLOGY: Human extracted teeth were collected and root filled. After post space preparation and cleaning with 10% ethylenediaminetetraacetic acid for 30 s, teeth were assigned to four groups (n = 11) according to etching procedure: (i) 37% phosphoric acid (H3 PO4 ) gel; (ii) 37% H3 PO4 liquid applied with an endodontic needle; (iii) 37% H3 PO4 liquid applied with an Endovac; (iv) no etching procedure (control group). Three teeth per group were sectioned longitudinally and prepared for SEM examination to evaluate the presence of smear layer, debris, sealer/gutta-percha remnants, and the number of open tubules. Eight teeth per group were bonded with an etch-and-rinse adhesive, and fibre posts were luted with a resin-based cement. After cutting, specimens were prepared for a push-out test. Data were analysed by anova and post hoc tests (P < 0.05). RESULTS: Improved smear layer removal was obtained in Group 2, followed by Group 1, Group 3, and the control group (P < 0.05). The mean values for the bond strength of the push-out test were: Group 1, 8.3 ± 2.9 MPa (coronal); 7.7 ± 3.0 (middle); 3.3 ±1.9 MPa (apical); Group 2, 7.8 ± 2.1 MPa (coronal); 6.9 ± 3.9 MPa (middle); 3.7 ± 1.3 MPa (apical); Group 3, 9.7 ± 2.8 MPa (coronal); 8.6 ± 2.1 MPa (middle); 6.9 ± 2.3 MPa (apical); and Group 4, 2.9 ± 3.0 MPa (coronal); 2.6 ± 2.0 MPa (middle); 1.1 ± 2.0 MPa (apical). CONCLUSIONS: Liquid phosphoric acid applied with an endodontic needle yielded better canal wall smear layer removal and higher bond strength values when an etch-and-rinse system was used.

Exploring the influence of placing bi-directional E-glass fibers as protective layer under a CAD-CAM resin composite on the fracture pattern.

OBJECTIVES: To investigate the influence of the presence and position of bidirectional E-glass fibers under a CAD-CAM resin composite on the fracture pattern evaluated both after quasi-static mechanical loading and after fatigue. METHODS: Rectangular specimens (10 mm-long, 5 mm-large and 4.2 mm-thick) were prepared and divided into four groups (n = 30/group). The control group (C-Group) consisted of a 4.2 mm-thick layer of monolithic CAD/CAM resin composite resin (Cerasmart, GC). In the 3 other groups including the placement of a fiber layer (F-Groups), the CAD/CAM resin composite layer was reduced to 3-, 2- and 1-mm thickness (F3-, F2- and F1-Groups, respectively). Two bonded layers of bidirectional E-glass FRC (Dentapreg, ADM A.S.) were bonded underneath and a light-curable resin composite base (Gaenial Posterior, GC) was then added to reach a total thickness of 4.2 mm for all samples. In each group, half of the specimens (n = 15) were submitted to quasi-static mechanical loading to failure in a universal testing machine. The other half (n = 15) was subjected to cyclic isometric stepwise loading until failure or completion of 105000 cycles (5000 cycles at 500 N, followed by five stages of 20000 cycles at 750 N, 1000 N, 1250 N, 1500 N, and 1750 N). The data were analyzed by Weibull statistics for quasi-static loading, and by the Kaplan-Meier product limit estimation procedure after fatigue. All fractured specimens were studied using light and electron microscopy techniques, and the types of fracture were determined. RESULTS: For quasi-static mechanical loading, significant differences were observed for Weibull modulus and characteristic strength between groups, with values ranging from 10.8 to 22.4 for the former and from 2336.6 to 2974.7 for the latter. Also, survival after stepwise fatigue revealed statistically significant differences between groups (p < 0.05), the lowest values of cycles before failure being observed for F1-Group - Median = 61223 (50415; 65446) - as compared to the other groups - C-Group: Median = 89005 (86189; 98195); F3-Group: Median = 85198 (77279; 87860); F2-Group: Median = 89306 (87454; 97024). Both in quasi-static loading and after fatigue, the observation of fracture modes revealed major differences. While all fractures were vertical (split) in C-Group, the majority of the specimens in F-Groups presented some degree of horizontal deflection of the crack. In all deviated fractures, fractographic analysis confirmed a toughening effect of the fiber layer. SIGNIFICANCE: The present in vitro work tends to show that the fracture pattern of CAD-CAM resin composites is favorably affected by the presence and position of an underlying bidirectional E-glass fiber layer. The placement of E-glass fibers under a CAD-CAM resin composite may therefore represent an interesting strategy to reduce the risk of catastrophic restoration failure, which could be integrated in the development of the new generation of indirect materials, possibly in 3D-printing approaches.

Atypical facial pain related to apical fenestration and overfilling.

AIM: To report a case of apical fenestration and overfilling in which unusual pain characteristics made differential diagnosis challenging. SUMMARY: A 32-year-old woman with diffuse, spontaneous, moderate pain in the maxillary left posterior sector, exacerbated by masticatory and facial muscle movement, with intense sporadic electric-shooting pain, underwent clinical examination and 3D cone beam computed tomography (CBCT). Apical fenestration with protrusion of the mesial root of tooth 26 beyond the buccal cortical plate, extrusion of canal filling material into the soft tissues and a periosteal reaction were detected. Surgery was performed under the operating microscope. The filling material and surrounding fibrous tissue were located, dissected from healthy soft tissues and removed. The mesiobuccal root apex was resected with a bur to within the bony crypt. A root end was prepared and filled with Tech Biosealer RootEnd™ (Isasan, Como, Italy). At the 2-week recall, the patient had complete resolution of the symptoms and good soft-tissue healing. The 1-year recall examination and intra-oral radiography confirmed complete resolution of the symptoms and health of periradicular tissues. KEY LEARNING POINTS: Apical fenestration may occur in 9% of cases and may be considered an anatomic predisposing factor for persistent pain after root canal treatment. This complication provides a considerable differential diagnostic challenge and is often misdiagnosed and mistreated. When correctly diagnosed through an accurate, multidisciplinary approach, it may be managed with a simple surgical procedure in which the endodontist should play a key role. Misdiagnosis and over treatment of apical fenestration, through the surgical management of chronic facial pain conditions, could lead to severe exacerbation of chronic pain, which may potentially become persistent or, indeed, intractable.

Comparative evaluation of the enamel margins roughness obtained with different finishing devices.

AIM: The aim of this in vitro study was to compare the surface roughness of enamel margins resulting by the use of rotating, sonic and ultrasonic devices for cavity margins finishing. METHODS: Forty-eight anterior intact teeth were selected for this study. Each item was sectioned 1 mm below the CEJ, perpendicular to the long axis of the tooth, with the carborundum separating disk mounted on the high-speed handpiece. With the same bur the crown was separated into two parts along the midline vertically. At the end 96 "half-crowns" were obtained. The samples were divided into 6 groups of 8 samples each, according to enamel margin's finishing technique (A and B: diamond ultrasonic tip; C: multisteel ultrasonic tip; D: fine diamond rotating bur; E: ultra-fine diamond rotating bur; F: sonicflex prep). The surface roughness evaluation of the enamel of each sample has been carried out by using a profilometer. The statistical analysis was performed with a balanced hierarchical ANOVA. RESULTS AND CONCLUSION: The results of this in vitro study showed that the enamel roughness obtained with sonic and ultrasonic devices was significantly higher than roughness obtained with rotating burs. Within the sonic and ultrasonic tips, the multisteel ones gave better results, that were comparable to diamond sonic device.

Optical Property Stability of Light-Cured versus Precured CAD-CAM Composites.

Objective: The aim of this study was to evaluate the optical property changes after staining of precured (PC) and light-cured (LC) composites. Materials and Methods: Specimens were prepared using different LC composites (GrandioSO-Voco, Filtek Z350-3M/ESPE, Opallis-FGM, and Kalore-GC) and four PC blocks (Grandio Blocs-Voco, Lava Ultimate-3M ESPE, Brava Block-FGM, and Cerasmart-GC) from the same manufacturers (n = 20). Baseline color, gloss, translucency, and fluorescence were evaluated. The staining protocol was performed for 15 days, and the final optical properties were reevaluated. Results: The changes in each property were calculated (ΔGloss, ΔTranslucency, ΔFluorescency, ΔE ∗ 00). Data were analyzed by ANOVA and Tukey's test (α = 5%). Changes in all properties were observed after staining for all materials, with darkening and reduction of gloss, fluorescence, and translucency. Nonsignificant differences were observed between the light-cured and precured materials of the same manufacturer for ΔG and ΔT, but significant differences existed for ΔF and ΔE ∗ 00. For ΔF, the only significant differences were observed between Brava Block and Opallis (smaller). For ΔE ∗ 00, only the light-cured composites GrandioSO and Z350 showed significantly less change than the corresponding blocks. Precured composites were affected the same way as light-cured ones by the staining in relation to the reduction of gloss and translucency. Conclusion: A higher reduction in fluorescence was observed for only one brand of block and was similar for the others. The two brands of light-cured materials showed less staining, while for the others, the staining was similar. The effects of staining vary according to the composite formulation.

Restoration of Severely Damaged Endodontically Treated Premolars: Influence of the Ferrule Effect on Marginal Integrity and Fracture Load of Resin Nano-ceramic CAD-CAM Endocrowns.

OBJECTIVES: To explore the ferrule effect on Resin Nano-Ceramic (RNC) premolar endocrown marginal integrity and fracture resistance. METHODS: Thirty-six root-canal-treated premolars were cut 2 mm above the cemento-enamel junction (CEJ). They were restored with standardized RNC computer-aided design/computer-aided manufacturing (CAD/CAM) restorations (Lava Ultimate, 3M Oral Care, St. Paul, MN, USA) and divided into three groups (n=12): endocrowns with a 3-mm endo-core (Group 1), endocrowns with a 3-mm endo-core and a 2-mm ferrule (Group 2), and conventional post-and-core crowns with a 2-mm ferrule (Group 3). All specimens were submitted to thermo-mechanical cycling loading (TMCL) (1.7 Hz, 49 N, 600 000 cycles, 1500 thermocycles). Margins were analyzed before and after the TMCL. In the second part of the experiment, the surviving specimens were submitted to unidirectional monotonic loading until fracture. Fragments were then analyzed using scanning electron microscopy (SEM) and the fracture mode was established. RESULTS: Endocrowns of Groups 1 and 2 performed better than conventional crowns (Group 3) in terms of marginal continuity. Differences in fracture load values within all groups were not statistically significant. Most of the specimens fractured in a non-repairable way. CONCLUSIONS: The present test failed to provide evidence of any kind of difference between endocrowns with and without a ferrule in terms of load-bearing capacity and marginal integrity after fatigue. Further studies are needed to confirm the role of the ferrule in adhesive restorations of endodontically treated teeth.

5-year retrospective evaluation of direct composite restorations in orthodontically treated patients.

OBJECTIVES: In patients affected by dimensional discrepancy between size of anterior maxillary and mandibular teeth, orthodontic therapy could be necessary to solve occlusal problems. However, anterior restorations are indicated to finalize the aesthetic aspect of the therapy. The aim of the present retrospective clinical study was to evaluate the long-term outcomes of direct additive composite restorations performed to correct anterior teeth discrepancies persisting after orthodontic treatment. METHODS: Patients with dimensional teeth discrepancy, subjected to a combined orthodontic-restorative treatment, between January 2009 and January 2019, were recalled for the present retrospective evaluation and divided in two groups according to the restoration performed: G1) diastema closure; G2) tooth shape modification. All patients, after ortho therapy, were subjected to a standardized restorative rehabilitation of the anterior area. All restorations were performed by a single experienced operator employing the same materials. During recall visits, two calibrated examiners evaluated the restorations and recorded USPHS data. Kaplan-Meier estimator and Cox-regression analysis were performed. Statistical significance was set for p < 0.05. RESULTS: 53 patient were included, with a total of 169 restoration (G1:110;G2:59). The mean study time period was 5 year (ranging from 6 month to 10 years). The overall survival rate of additive restoration was 2,59% (G1:2,07%; G2:0,47 p < 0.05). Chipping of the material was the most frequent adverse event (G1:13,64%; G2:1,69), followed by composite wear (G1:9,09%; G2:5,17). CONCLUSIONS: Based on the obtained results, good clinical performances were shown at a 5-year interval. A low number of failures were collected and most of them were classified as reparable. Only few cases needed complete reintervention. CLINICAL SIGNIFICANCE: Showing that a direct approach in restoring anterior teeth for diastema closure or shape modification is a valid alternative in terms of durability and aesthetics to more invasive procedure such as indirect restorations.

Digital vs. Freehand Anterior Single-Tooth Implant Restoration.

Replacing a single tooth in the anterior maxilla is one of the greatest challenges in dentistry. Both functional and aesthetic results are to be strictly pursued. Planning and executing such a case through a totally digital methodology eventually guarantee many advantages, above all patient's operative and postoperative comfort. To ascertain this, a BOP analysis was performed which allowed us to evaluate soft tissues health, and more; crestal bone resorption was measured to evaluate hard tissues stability. This assumption was studied through four cases in which patients were alternatively treated with analogic and digital techniques. Four homogeneous patients were recruited. They all needed to extract one of the upper incisors, due to different clinical reasons, and then to replace it with an implant. Each patient was treated with an immediate postextractive implant which was immediately loaded, and finally, analogical and digital techniques were compared. All patients underwent a preoperative CBCT examination. After surgery, patients were checked by the surgeon after 10 days and one month to evaluate the progress of healing and to exclude any prosthetic problem. At 6 months (T1), one year (T2), and three years (T3), intraoral x-rays were performed using customized centring devices, according to the parallel beam technique. All data have been collected in a table and statistically processed; mean and standard deviation were measured. All patients entered an oral hygiene program with six months recall. Dental hygienist checked the BOP at T1, T2, and T3. At every step, similar levels of BOP were recorded. About interproximal bone loss, all patients showed an initial moderate loss (between T1 and T2), followed by stable values between T2 and T3. Despite the important limitations of a study with few cases, these results show a similar outcome comparing digital and analogical methods.

Tridimensional Evaluation of the Interfacial Gap in Deep Cervical Margin Restorations: A Micro-CT Study.

CLINICAL RELEVANCE: Using a material that optimizes marginal seal when using a margin elevation technique to manage deep class II cavities should enhance clinical outcomes. SUMMARY: Objectives: The purpose of this laboratory study was to perform a tridimensional interfacial gap evaluation of class II cavities with enamel and dentin cervical margins, before and after cyclic fatigue, restored with different nanohybrid resin composites.Methods and Materials: Standardized class II cavities were performed on 48 intact maxillary premolars, placing the mesial cervical margin 1 mm above the cement-enamel junction (CEJ) and the distal cervical margin 1 mm below the CEJ. Specimens were treated with two-step self-etch adhesive (Clearfil SE Bond2) and divided into six groups according to the restoration technique. Microcomputed Tomography imaging was executed before and after 1,000,000 cycles of chewing simulation at 50 N. Tridimensional interfacial gaps, expressed as cubic millimeters, were analyzed through a standardized software flowchart (Mimics). Data were analyzed with a two-way analysis of variance and Tukey post hoc tests (α=0.05).Results: Restoration technique (p=0.001) and chewing simulation (p=0.00001) significantly influenced interfacial gap on dentin but not on enamel. The post hoc test showed that, on dentin margins, flowable resins had a lower gap at baseline but a higher gap after chewing simulation, especially when a 2-mm-thick layer was applied, compared with nanohybrid and bulk-fill composites.Conclusions: Based on the obtained results, no differences in interfacial gap volume were found on enamel margins. On dentin margins, flowable resins showed better marginal seal at baseline, but they seem to be more prone to interfacial degradation during chewing simulation than traditional composites.

Early biofilm colonization on polished- and glazed-zirconium ceramic surface. Preliminary results.

AIM: The purpose of this study was to evaluate the effect of ceramic surface polishing procedure on the early dental biofilm formation on zirconium ceramics. METHODS: Twenty samples (discs shape) of tetragonal zirconium polycrystal stabilized with yttrium ceramics (Y-TZP) for LAVA system were fabricated (5 mm diameter and 1.5 mm thickness). Two patients with high level of dental hygiene were selected for this study. Oral devices covering the crowns of the upper premolars and molars were fabricated for each participant. Glazed and polished samples of Y-TZP ceramics were fixed on the vestibular and palatal zones of the devices. After 20 min (8 samples) and 1 h (8 samples) in the oral environment, the samples were removed and analyzed in a scanning electron microscope. The surface topographies of 4 ceramic samples (2 glazed and 2 polished) were analyzed (control group: without exposition in oral environment). RESULTS: The glazed samples showed a more irregular surface than polished samples. Deposition of granular aggregates was verified on all the samples in the two times of the study analyzed. This granular material coated more intensely on irregular areas, and its thickness increased after 1 h. No difference was observed as to bacterial morphology in any time of the study. Cocci and rods-shaped prevailed. CONCLUSIONS: Glazed surfaces presented larger tendency to dental biofilm accumulation.

Longevity of class 2 direct restorations in root-filled teeth: A retrospective clinical study.

OBJECTIVES: To evaluate retrospectively the longevity of endodontically treated teeth restored with direct resin composite without cusp coverage, with or without the insertion of fibre posts. The null hypothesis was that direct restorations with fibre posts perform better than those without fibre posts. METHODS: Patients recruited for this study were treated in the Department of Cariology and Operative Dentistry, University of Turin, between 2008 and 2011. In total, 247 patients with 376 root treated posterior teeth, restored with direct resin composite, were recalled for a control visit. Only second-class cavities were considered. Two groups were defined based on the absence (Group A) or presence (Group B) of fibre post. Failures and complications, such as periodontal failure, endodontic failure, tooth extraction, root fracture, post fracture, post debonding, replacement of restoration, crown displacement, and coronal-tooth fracture, were noted. Functional restoration quality was evaluated following the modified USPHS criteria. Data were evaluated statistically with ANOVA. RESULTS: Group A consisted of 128 patients with 178 restorations (88 premolars, 90 molars) with a median follow-up of 34.44 months. Group B consisted of 119 patients with 198 teeth (92 premolars, 106 molars) with a median follow-up of 35.37 months. Direct restorations with fibre posts were statistically significantly more functional (95.12% success) than those without fibre posts (80% success) because of less marginal discolouration, better marginal integrity, and higher restoration integrity. CONCLUSIONS: The null hypothesis was accepted because direct post-endodontic restorations with fibre posts performed better than restorations without posts after 3 years of masticatory function. CLINICAL SIGNIFICANCE: An evaluation of the longevity of post endodontic direct restoration would seem to enhance the fiber post insertion within a composite restoration to reduce clinical failures.

Mitochondrial DNA variation in cultivated and wild potato species (Solanum spp.).

The European cultivated potato, Solanum tuberosum subsp. tuberosum, has 6 related cultivated species and more than 200 wild relatives. In Solanum spp., studies of cytoplasmic organelles have been mainly confined to the plastid DNA composition of cultivated and wild species. In this study, 53 genotypes of 30 potato species belonging to the subsections Estolonifera and Potatoe, 2 tomato species, and a black nightshade genotype were examined using PCR markers to evaluate mitochondrial DNA diversity and assess whether mtDNA variability was correlated with series classification, geographical origin, ploidy, and endosperm balance number (EBN). The markers used revealed interspecific mtDNA variability in Solanum spp. and identified 13 different haplotypes. Intraspecific variability was also observed in a few species and genomic regions. Cluster analysis allowed arrangement of the 13 haplotypes into 7 subgroups, and statistical association tests showed significant relationships between mitochondrial patterns detected by molecular analysis and ploidy, EBN, and geographical origin. On the whole, the evolutionary patterns for the genomic regions analyzed reflected the species relationships established on the basis of morphological and molecular (nuclear and plastidial DNA) data. The mtDNA variability shown is also important for better characterization of genetic resources for potato breeding.

Direct gene transfer in potato: a comparison of particle bombardment of leaf explants and PEG-mediated transformation of protoplasts.

Direct gene transfer methods in potato would facilitate the transfer of multiple genes and the manipulation of metabolic pathways in this species. In this study, up to 1.8 transformation events per shot (=0.5 per bombarded leaf) and 67.2 events per million protoplasts treated were obtained with particle bombardment and PEG-mediated direct DNA uptake, respectively. Limited disassociation of both HPT and GUS genes appeared to occur during the process of integration in only 19% of transformants. A large number of transformed potato plants with transgene expression at levels comparable to Agrobacterium-mediated transformation was obtained. High levels of GUS expression were only obtained in lines derived from PEG treatment. No correlation between the number of gene insertions and gene expression levels was found, suggesting that multiple insertions may have little or no effect on transgene expression.