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External Cervical Resorption: A case report
Get PDFAim. External cervical resorption is a form of root resorption which begins in the cervical region of the tooth and spreads out in the thickness of the dentin in an irregular way; clinically, it may be not visible and, as it is generally asymptomatic before involvement of the pulp, it is often an occasional finding in radiographic examination. Several factors are related to its aetiology. This paper reports a case of external cervical resorption in a mandibular right first molar of a 17-year-old patient; the tooth was extracted and histological analysis was performed.
Methods. Radiographic examination showed a progressive external cervical resorption of the lower right first molar; extension of the lesion and pulp involvement indicated tooth extraction; the sample underwent histological analysis.
Results. The histological study confirmed the presence of vascular connective tissue in the resorptive lacunae, invading the dentin from the external surface of the root, and perforations from the defect into the pulp; it was also noticed the presence of bone-like tissue
SEM-morphology in dentinogenesis imperfecta type II: microscopic anatomy and efficacy of a dentine bonding system
No full textAIM:
Dentinogenesis Imperfecta is a hereditary defect consisting of opalescent teeth composed of irregularly formed and undermineralised dentin that obliterates the coronal and root pulpal chambers. The aim of this study was to examine the morphology of permanent human enamel, dentine and the dentine-enamel junction, in individuals affected by Dentinogenesis Imperfecta type II in undercalcified sections using scanning electron microscope (SEM) to compare the findings to the normal morphology, and to study the efficacy of modern bonding system to dentine and enamel DI type II affected.
MATERIALS AND METHODS:
Four third molars extracted from two 19 year-old subjects (one patient affected by Dentinogenesis Imperfecta type II) were included in resin, two divided in slices with a air-cooled diamond disc, and two used to study the characterisation of the resin-dentin interface. The sections of the teeth were examined by means of SEM. The slices were finished up with abrasive paper (400, 600, 1000, and 2000), the half surfaces obtained were etched with 37% phosphoric acid and then joined up to the stubs for SEM analysis. SEM Stereoscan 440 Leica with magnifications of 20X, 100X, 250X, 1000X, 2000X, 3000X was used. As control group were used four third molars with normal anatomy.
RESULTS:
This study shows that the permanent enamel from patients with DI exhibits few structural changes. No relationships were found between enamel morphology and the DI type II. Enamel appeared to be regularly mineralised. The major findings were anomalies in the dentine-enamel junction, locally a lower degree of mineralisation and an undulating morphology. The dentine showed absence of tubules.
CONCLUSION:
This study confirms that the problem with teeth affected by DI type II is the defect in dentine and weakness in the way the enamel is attached to the dentine. The adhesive system tested is not able to create a real hybrid layer in dentine DI type II affected and seems to be less effective than on normal substrates
DIRECT ADHESIVE REHABILITATION WITH DOUBLE INDEX TECHNIQUE: A CASE REPORT
No full textNowadays patients desire not only to restore function and phonation, but above all to restore or gain good aesthetics in the anterior upper and lower jaws. "Minimally invasive" preparation techniques have been introduced, which have become today the state-of-the-art in daily clinical practice for the aesthetic rehabilitation of the anterior teeth. The most convenient clinical situation that meets these concepts is the correction of the aesthetics of a smile with only additive restorations. In this paper we present the use of a double index technique, palatal and vestibular, intended for multiple, up to 6 teeth per arch, direct aesthetic composite veneers of the anterior teeth
Shaping ability of reciproc R25 file and mtwo system used in continuous and reciprocating motion
Get PDFAim: Nickel–titanium (NiTi) instruments were designed to be used in continuous rotation mode with controlled speed and torque and a sequence of different sizes. The reciprocating motion was purposed to improve cyclic fatigue of rotary instruments if compared to the conventional rotation. The purpose of this work was to compare the shaping ability of Reciproc R25, Mtwo #25/0.06 used as a single file, and Mtwo sequence used in reciprocating motion and in continuous rotation.
Materials and methods: Forty-eight endodontic training resin blocks ISO 15, 2% taper, 7 mm radius, and a 60° angle of curvature were shaped with four different protocols. Group I (Rrsf) was shaped with Reciproc R25 used as a single file in a reciprocating motion. Group II (Mrsf) was shaped with Mtwo #25/0.06 used as a single file in a reciprocating motion. Group III (MSrec) was shaped with Mtwo sequence in reciprocating motion, and finally, group IV (MSrot) was shaped with the Mtwo sequence used in continuous rotation. Preoperative and postoperative images of the simulated canals were taken under standardized conditions and combined exactly. The amount of resin removed was determined at both the inner and outer sides of the canal curvature. The ability of the instruments to remain centered in the canal was determined by calculating a centering ratio. These data were analyzed statistically using two factors analysis of variance (ANOVA) with Bonferroni correction (Bonferroni post-hoc test).
Results: Group Rrsf produced a greater enlargement of the canal, especially on the outer side, in the apical and middle third (p < 0.05). Group MSrot produced a lower enlargement in the middle third (p < 0.05). Group Rrsf displayed a lower centering ratio in the apical third (p < 0.05). Group MSrot displayed a lower centering ratio in the coronal third (p < 0.05).
Conclusion: The shaping of simulated canals using a sequence of instruments in continuous rotation resulted in a more centered preparation of the apical third. The reciprocating motion for all tested instruments produced a bigger enlargement of the canals.
Clinical significance: Reciprocating movement results in a more pronounced canal enlargement but appears to be less respectful of the original canal curvature and produces more apical transportation than a sequence of rotary NiTi files with the same ending apical size
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
In vitro evaluation of the post-space depth reading with an intraoral scanner (IOS) compared to a traditional silicon impression
Get PDFscanpost,
compared to a traditional silicon technique.
Methods. Six extracted bicuspids were decoronated and endodontically treated. After having prepared the space for the
posts, a structure in pink acrylic resin was created with two resin elements. At the center of the structure one sample was
put at a time. Digital and traditional impressions were taken for each sample.
Digital impressions were developed through the Computer-aided design (CAD) software in order to integrate the scanner
results into a three-dimensional grid to make the measurements. A K-file was used to measure the length of the postspace
of each sample obtained through the traditional silicon impression and subsequently the measurement results were
reported on a millimeter gauge. Furthermore, an assessment of the width of the entrances of the post-spaces was carried
out.
Results. The mean reading depth discrepancy expressed in percentages (19.58%) indicates that the digital impression
with current technologies fails to impress clearly the post-space. Standard deviation of the data expressed in percentage
is 13.89, suggesting that the values were not similar to each other. In two cases the digital technique has achieved less
than 10% difference compared to the traditional technique, but there have been also cases in which the variation in depth
has reached almost 40%.
The samples that showed the minor discrepancy between the two techniques expressed the widest post-space entrance.
Conclusions. In this in vitro study, the application of the IOS for the post-space reading in order to deliver an anatomic
post has been proven to be still not reliable, as there are still depth reading limitations for the narrow root channels. In
fact, in this type of channels it is difficult to reach with the light beam of the IOS the deepest areas of the post-space, with
a consequent incomplete post-space reading
Percentage of Gutta-percha–filled Areas in Canals Obturated by 3 Different Techniques with and without the Use of Endodontic Sealer
No full textIntroduction: This study had 2 purposes: to compare the Microseal, continuous wave, and Thermafil techniques and to compare the same techniques with and without endodontic sealer. Methods: Ninety extracted mandibular premolars were allocated into 6 groups obturated with Microseal (Analytic, Glendora, CA) and sealer (Mseal), Microseal without sealer (Mnoseal), System B (EIE Analytic Technology, Orange, CA) and sealer (SBseal), System B without sealer (SBnoseal), Thermafil (Dentsply, Tulsa Dental, Tulsa, OK) and sealer (Tseal), and (Tnoseal) Thermafil without sealer (Tnoseal). The teeth were sectioned at 1 and 3 mm from the apex. The total area of each canal segment was measured, and the areas were converted to the percentage of gutta-percha filled areas, sealer -filled areas, and void areas. Data obtained were statistically elaborated using the t test (P <= .01). Results: At 1 mm, SBseal produced a higher VA than Mseal and Tseal. At 3 mm, Tseal produced a lower VA than Mseal and SBseal, whereas Mseal produced a lower VA than SBseal (P > .01). At 1 mm, Tnoseal produced a significantly higher VA than Mnoseal and SBnoseal (P = .001). At 3 mm, Tnoseal produced a higher VA than Mnoseal and SBnoseal (P = .01). Tnoseal produced a significantly higher VA than Tseal both at 1 mm (P = .001) and 3 mm (P = .001). Conclusions: Endodontic space filling is traditionally provided by sealer and gutta-percha. In this study's conditions, gutta-percha alone showed better filling at both 3 mm and 1 mm in the Microseal and System B techniques. Considering the limits of our study, we can affirm that endodontic techniques using sealer could counteract thermoplasticized gutta-percha progression
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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