1,720,979 research outputs found
In vitro assessment of normal and pathological dental structures by nuclear magnetic resonance micro-imaging at high field
Full text linkAims: Aim of this work is to analyze the various field of application of Magnetic Resonance Imaging in endodontics and highlight its current advantages and limitations due to understand its future application in research and clinical practice. The effectiveness in revealing the presence or absence of a pathological condition affecting enamel, dentin, endodontic space and the quality of the apical seal of an endodontic sealing technique was investigated.
Materials and methods: Three extracted monoradicular teeth were analyzed using a Bruker Avance-400 high-resolution spectrometer operating at 9.4 T with a microimaging probe (10 mm internal diameter), equipped with a gradient unit characterized by a maximum gradient strength of 1200 mT/m and a rise time of 100 μs. XWINNMR® and ParaVision® 3.0 software were employed for data acquisition and analysis. Images of teeth were weighted in T2 at different TE to measure T2 relaxation times and in Apparent Diffusion Coefficient (ADC) in different regions of interest (ROI).
Results: T2 and ADC values were obtained at different ROI. Clear images of carious lesions, periodontal tissues, pulpar remnants and endodontic materials such as guttapercha cones were acquired. Presence of microcracks and a calcification of the pulp were also clearly differentiated.
Conclusions: Micro MRI is a non-invasive, non-destructive tool for the assessment of pathological conditions affecting dental hard and soft tissues, and it may help in finding endodontic procedural mistreatments such as incomplete detersion or inadeguate tridimensional filling in vitro
Cone-beam computed tomographic analysis on root and canal morphology of mandibular first permanent molar among multiracial population in Western European population
Full text linkObjectives: In the present study, confluent canals in the mandibular first molar's mesial root were investigated in an Italian population by means of cone-beam computed tomography (CBCT). Materials and Methods: A total of 200 molars, selected from the CBCT examinations of 130 patients who required this type of X-ray study as part of their dental treatment, were examined. The evaluated parameters were number of canals, root canal system configuration, presence of apical confluences, distance between confluences and apical foramina, which canal had a higher degree of curvature, and symmetry between left and right elements in the same individual. Statistical Analysis Used: Percentages of the cases were reported. Results: All the examined roots presented two canals. In 59% of cases, a Vertucci Type IV canal configuration was observed, while in 41% of cases, a Type II configuration was observed. Apical confluences were present in 41% of cases. The average distance between confluences and apical foramina was 2.85 mm. When confluences were present, the mesiobuccal canal showed a higher degree of curvature in 78% of cases. Symmetry in Vertucci configuration was seen in 88% of cases. Conclusions: Apical confluences in the mesial roots of mandibular molar can be present in a significantly high number of cases, and their recognition is essential to prevent the iatrogenic errors during canal instrumentation
One-stage laser-microtextured implants immediately placed in the inter-radicular septum of molar fresh extraction sockets associated with GBR technique. A case series study
Full text linkBackground: The outcome of one-stage trans-mucosal immediate implants with simultaneous guided bone regeneration (GBR) technique has become highly predictable. Furthermore, when this approach is performed to place one-stage implants into the inter-radicular septum of fresh extraction sockets in the molar region, the risk of incorrect emergence profile and off-angle loading is reduced. The aim of the present study was to clinically evaluate the horizontal hard and soft tissue changes, and radiographically the vertical socket walls remodeling, and the early peri-implant marginal bone loss (EMBL) following the placement of immediate one-stage implants in the inter-radicular septum of molar fresh extraction sockets, associated with a collagen membrane. Materials and methods: Twenty patients were selected to receive a one-stage implant with laser-microtextured collar surface into the inter-radicular septum of a fresh molar extraction sockets, associated with a simultaneous placement of a collagen membrane. Intraoral radiographs and model casts were used for the evaluation. Correlation between the amount of the keratinized tissue thickness (KTT) with EMBL was also analyzed. Results: After 4 months, the vertical radiographic mesial and distal EMBL around implants was of 0.06 ±0.01 mm and 0.04±0.02 mm, respectively, with no statistically significant difference between T0 and T1 (P > 0.05). No statistical differences were found also for each radiographic measure used for the examination of implant sites vertical bone changes (p > 0.05). Clinically, horizontal changes of the bucco-lingual central width were found statistically significant (p 0.05). In addition, no statistically significant correlation between EMBL and the amount of KTT was found (P > 0.05). Conclusions: Results suggest that the immediate placement of one-stage laser-microtextured implants could provide advantages in preserving the extraction socket's hard and soft tissue remodeling, and the peri-implant marginal bone level before the prosthetic loading
Influence of restorative margins position on one-stage laser-microgrooved implants-supported single screwed crowns: a clinical, biochemical, and microbiological analysis
No full textAim: To clinically, biochemically, and microbiologically evaluate the influence of crown margins position on one-stage laser-microgrooved implants. Materials and Methods: Twenty-one-stage titanium implants with a laser-microgrooved collar surface, supporting screwed, single crown restorations, were placed in 20 partially edentulous patients and evaluated. Clinical parameters included modified plaque index, modified gingival index, peri-implant probing pocket depth, bleeding on probing, and distance between implant shoulder and mucosal margin. The parameters were recorded at baseline (crowns delivery) and at every 6-month recall visit, until the end of the 3 years follow-up period. At the same time intervals, radiographic marginal bone levels were assessed at the mesial and distal aspect of the implant sites. For biochemical analysis, the volume of the peri-implant sulcus fluid, and its levels of interleukin-1beta (IL-1β), interleukin-6 (IL-6), and of tumor necrosis factor-α, were utilized to evaluate the peri-implant health conditions at the end of the 3-year follow-up period. At the same time, microbiological analysis, including the concentration of five putative periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythensis), were assessed. The crown margins positions were classified into four groups (A = intracrevicular position >2 mm, B = intracrevicular position ≤2 mm/<1 mm, C = intracrevicular position ≤1 mm/<0 mm, and D = extracrevicular position), and the biochemical, and microbiological parameters were evaluated at 3 years. Results: No statistical differences of clinical and biochemical parameters were found between the four groups. In group A, compared to groups B, C, and D, a statistically significant higher concentration of putative periodontal pathogens was found. Conclusions: Results showed that the intracrevicular deeper position of the restoration margin does not influence the clinical and biochemical peri-implant parameters. The deeper position of the crown margin is associated with a greater amount of putative periodontal pathogenic microflora colonization
In vitro evaluation of carrier based obturation technique: a CBCT study
Full text linkAIM:
The goal of the study was to compare the ability of two different carrier based obturation (CBO) techniques to reach working length and fill in three-dimensions root canal systems, by using CBCT.
MATERIALS AND METHODS:
Twenty-six extracted molars were scanned with CBCT and 40 curved canals were selected (between 30° and 90°) and divided in two similar groups (n=20). All canals were prepared up to size 25 taper .06 using nickel-titanium instrumentation. The canals in the Group SC were obturated using Soft-Core obturators (Kerr, Romulus, Mi, USA), while Group TH canals (n= 20) were obturated using Thermafil Endodontic Obturators (Tulsa Dental Products, Tulsa, OK, USA), strictly following manufacturers' instructions for use. The obturations were analyzed by means of CBCT to measure the distance from the apical limit of obturation to the apical foramen and the presence of voids inside root canals.
RESULTS:
There was no significant difference between the two groups in the mean distance of the apical extent of the obturation (t test, p>0.05). Overfilling occurred in only 3 cases (2 in Group TH and 1 in Group SC). The percentages of voids in both groups were very low with no significant difference (Z test, p>0.05).
CONCLUSIONS:
The two tested CBO techniques showed similar positive results in terms of performance, even if, after checking with verifiers, in most cases the size of the selected Soft-Core obturator was one size smaller than Thermafil
A comparative study of mechanical resistance of two reciprocating files
Full text linkBackground: To evaluate the cyclic fatigue resistance of two different Nickel-Titanium instruments, Reziflow (Komet, Brasseler GmbH & Co., Lemgo, Germany) and WaveOne Gold (Dentsply Maillefer, Ballaigues, Switzerland). Material and Methods: Two groups of 20 different NiTi endodontic instruments of identical tip size of 0.25 mm were tested; Reziflow and Wave-One Gold primary. Cyclic fatigue testing was performed in a stainless steel simulated root canal manufactured by reproducing the instrument's size and taper. A simulated root canal with a 90 degrees angle of curvature and 5 mm radius of curvature was constructed for the instruments tested. The centre of the curvature was 5 mm from the tip of the instrument and the curved segment of the canal was approximately 5 mm in length. Both the instruments were used in the same preset program specific for the WaveOne instruments. Each instrument was rotated until fracture occurred and the time to fracture (TtF) and the length of the fractured fragment were recorded. Means and standard deviations of TtF and fragment length were calculated and data were subjected to statical analysis (P < 0.05). Results: Statistically significant differences (P < 0.05) were noted between Reziflow and WaveOne Gold instruments. There were no significant differences (P > 0.05) in the mean length of the fractured fragments between the instruments. Conclusions: Rezifllow instruments were associated with a significantly higher cyclic fatigue resistance than WaveOne Gold instruments
Effectiveness of Xenograft and Porcine-Derived Resorbable Membrane in Augmentation of Posterior Extraction Sockets with a Severe Wall Defect. A Radiographic/Tomographic Evaluation
Full text linkObjectives: The aim of the present prospective study was to evaluate, by means of intraoral periapical radiographs and cone-beam computed tomography, hard tissue changes after ridge augmentation procedures in posterior extraction sockets with severe wall defects.
Material and Methods: Twenty patients, with a non-restorable premolar/molar tooth and severe wall defect, were enrolled in the present study, and underwent single-tooth extraction. Extraction sites were grafted with porcine-derived bone covered by porcine-derived collagen membrane. Intraoral periapical radiographs and cone-beam computed tomography scans, obtained at enrolment, and 6 months after ridge augmentation procedures were analysed and compared.
Results: In the intraoral periapical radiographs, mean vertical bone gains detected at the distal, central and mesial aspects of the extraction sockets were 3.5 (SD 1.1) mm, 8.2 (SD 2.1) mm, and 3.9 (SD 1.7) mm, respectively. In the cone-beam computed tomography scans, the mean vertical bone gains detected at the more vestibular and more palatal aspects were 4.4 (SD 1.9) mm, and 3.3 (SD 2.8) mm, respectively. The mean horizontal bone gain was 3.5 (SD 1.6) mm. In all examined defects, mean vertical and horizontal bone levels showed a statistically significant increase (P < 0.05) at 6 months after extraction.
Conclusions: Within the limits of this study, the results suggest that porcine-derived bone graft covered by a collagen membrane can support significant vertical and horizontal bone gain at posterior post-extraction sockets with severe wall defects
Cone-beam computed tomography in the assessment of periapical lesions in endodontically treated teeth
Full text linkObjective: This study aimed to evaluate the relationship between the quality of the coronal restoration and the root canal filling on the periapical status of endodontically treated teeth using CBCT. Materials and Methods: CBCT data were obtained from the records of patients who deny any dental treatment in the 2 years prior to the CBCT examination. CBCT images (90 kVp and 7 mA, exposure time of 23 s, and a voxel size of 0.2 mm, with a field of view of 13 cm × 13 cm) of 1011 endodontically treated teeth were observed. A score was given to the quality of the root filling and the quality of the coronal restoration. Statistical Analysis Used: Data were statistically analyzed to correlate the periapical status with gender, dental group. and quality of endodontic treatment and restoration (Chi-square test with a significance level of P 0.05). A statistically significant factor (Chi-square test, P < 0.0001) resulted when different qualities of sealing were compared. Conclusions: CBCT showed that high-quality root canal treatments followed by an adequate coronal sealing restoration avoid the presence of periapical periodontitis in time
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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