Luiz Fernando Machado Silveira

Morphologic Analysis of the Root Apex in Human Teeth

INTRODUCTION To determine the morphologic shape and position of the root apex and the major foramen in maxillary and mandibular teeth. METHODS A total of 845 maxillary and mandibular human teeth root specimens were evaluated. Each root specimen was measured at each root apex by using a calibrated microscope at a magnification of 20x. The anatomic parameters evaluated included the position of the root apex and the major foramen (in the center, buccal, lingual, mesial, or distal) and shapes of peripheral contours of the major foramen (rounded, oval, asymmetric, and semilunar) and root apex (rounded, flat, beveled, and elliptical). All data were summarized, and means, frequencies, and percentages were calculated for each group of specimens (incisors, canines, premolars, and molars). RESULTS The most frequent root apex morphology in maxillary and mandibular teeth was the round shape (35.1%). The most frequent shape of the apical foramen was round (52.9%) or oval (25.2%). The major location of both the root apex (39.7%) and the major foramen (58.4%) was in the center of the root. CONCLUSION The most frequent root apex morphology and apical foramen in the maxillary and mandibular teeth was the round followed by the oval shape. The most prevalent location of the root apex and the major foramen was in the center followed by the distal position.

Early flaring and crown-down shaping influences the first file bind to the canal apical third.

The determination of the apical constriction, its diameter and correct cleaning are significant for the biological response in the critical apical zone. Kerekes and Tronstad evaluated morphometrically molars and reported a wide variation of constriction sizes. Additionally, the continuous cement deposition on the constriction throughout life alters its shape and size. There is a wide variation in the canal apical diameter in all tooth groups what hinders the decision making of how much to enlarge the canals. Frequently, the first file to bind does not reflect the apical canal diameter. Clinically, the estimative of the apical diameter is not precise even with the adjunct use of radiographs or electronic apex locators. Stabholz et al. demonstrated that early flaring is critical to tactile determination of the apical diameter. Without early flaring the apical diameter was determined in only 32.3% of the cases, while after this procedure the determination increased to 75%. Therefore, the tactile sensitivity determines more accurately the number of instruments required for the enlargement of the apical region. In spite of this, the tactile sensitivity does not determine whether the instrument is bound just at the constriction zone or if interferences along the root canal are negatively influencing the apical binding. Leeb and Philippas reported that the normal dentin deposition promotes the root canal constriction and narrows the cervical region in molars. Irregularities of the walls and/or curvatures of the root canal can exert a pressure against the file and interfere with the practitioner’s ability to determine whether the binding occurred at the apical region. The

In vivo comparison of the accuracy of two electronic apex locators.

The aim of this study was to analyse in vivo the accuracy of two apex locators, Root ZX and Novapex, to determine the position of the apical constriction. Twenty-three human single-rooted teeth to be extracted for periodontal reasons constituted the experiment. Endodontic access was obtained and the apical constriction was determined by one of the apex locators after initial crown-down preparation. When the electronic marker indicated that the tip of the endodontic file was at the apical constriction, the teeth were filled with composite and then surgically removed. The presence of the endodontic file tip at the apical constriction was evaluated stereomicroscopically (30×) and confirming radiographs were exposed. The accuracy of Root ZX and Novapex was 91.7% and 81.8% respectively. Within the limits of this study, the evaluated apex locators have a similar clinical performance for the apical constriction location.

Restoration of posterior teeth using occlusal matrix technique

This article describes a technique for duplicating occlusal surface anatomy using the Biteperf device. Duplication requires an intact occlusal enamel surface and is only indicated when caries lesions are hidden. The occlusal matrix technique allows for preservation of all anatomic details. When the last layer of composite has been placed, the occlusal matrix is forced into the uncured composite to replicate the original occlusal surface, instead of performing manual curing and shaping as in the standard approach. It is technically possible to achieve this effect with any material that is able to copy anatomic details. The main benefits of the occlusal matrix technique, more precisely the Biteperf, are the technical ease of use due to its simplicity and its high accuracy in reconstructing occlusal morphology.

Crown fragment reattachment in anterior-fractured tooth: A five-year follow-up

Treatment of anterior dental fractures often requires an immediate procedure. Reattachment of the fragment to its original position is an optimal approach to aesthetic and functional rehabilitation. This paper reports the case of a permanent maxillary lateral incisor with crown fracture treated by adhesive fragment reattachment. Follow-up radiographs over 5 years demonstrated the satisfactory resolution of the clinical case.

Clinical technique for invasive cervical root resorption

This clinical case report describes the diagnosis and treatment of an external invasive cervical resorption. A 17-year-old female patient had a confirmed diagnosis of invasive cervical resorption class 4 by cone beam computerized tomography. Although, there was no communication with the root canal, the invasive resorption process was extending into the cervical and middle third of the root. The treatment of the cervical resorption of the lateral incisor interrupted the resorptive process and restored the damaged root surface and the dental functions without any esthetic sequelae. Both the radiographic examination and computed tomography are imperative to reveal the extent of the defect in the differential diagnosis.

Response of the periapical tissue of dogs' teeth to the action of citric acid and EDTA

The purpose of this study was to analyze the inflammatory response of dogs periapical tissues to 17% trisodium EDTA salt (pH 8.0) and 1% citric acid (pH 2.0). Saline was used as a control. Six adult dogs were used as the biological model of the study. The experimental units comprised 56 roots of mandibular molars (first and second) and premolars (first, second and third). After coronal opening, pulpectomy and root canal instrumentation were performed using the above-mentioned irrigating solutions. After 24 and 48 hours, the animals were euthanized and the teeth and their supporting tissues were removed and histologically processed. The sections were stained with hematoxylin and eosin and analyzed histopathologically with a light microscope at x100 magnification. The histological analysis focused on the occurrence of acute inflammatory response. The presence of swelling, vasodilatation and inflammatory cells were evaluated and the degree of inflammation was determined for each case. Data were analyzed by Fishers exact test using the SPSS software with a confidence interval of 95% (p<0.05). 17% EDTA and 1% citric acid caused inflammatory responses in dogs periapical tissues with no significant differences to each other or to saline (control) at either the 24-hour (p=0.482) or 48-hour (p=0.377) periods. It may be concluded that the inflammatory response was of mild intensity for the tested substances.

The effect of different organic solvents on the degradation of restorative materials

Objective: To evaluate the solubility of three restorative materials exposed to the different endodontic solvents. Materials and Methods: The organic solvents eucalyptus oil, xylol, chloroform, and orange oil, with distilled water as the control group was utilized. The restorative materials light-cured resin (Filtek Z250/3M ESPE), light-cured-resin-reinforced glass ionomer (Riva Light Cure LC/Southern Dental Industries SDI]) and resin-modified glass ionomer (Vitremer/3M ESPE) were analyzed. A total of 50 disks containing specimens (2 mm Χ 8 mm Ψ) were prepared for each of the three classes of restorative materials, which were divided into 10 groups (n = 5) for immersion in eucalyptus oil, xylol, chloroform, orange oil or distilled water for periods of either 2 min or 10 min. The means of restorative material disintegration in solvents were obtained by the difference between the original preimmersion weight and the postimmersion weight in a digital analytical scale. Data were statistically analyzed by two-way analysis of variance while the difference between the materials was analyzed by Student-Newman-Keuls test. The significance level set at 0.05. Results: Vitremer showed the highest solubility, followed by Riva LC, and these were statistically different from eucalyptus oil, xylol, chloroform, and distilled water (P < 0.05). Regarding the immersion time in solvents, there were no significant differences between the two tested periods (P > 0.05). Conclusions: The solvents minimally degraded the composite resin, although they did influence the degradation of both resin-modified glass ionomer resin and resin reinforced with glass ionomer.

Crown-down preflaring in the determination of the first apical file

In this study, scanning electron microscopy (SEM) was used to evaluate the adaptation of the first apical file after preflaring in mesiobuccal (MB) and mesiolingual (ML) canals of mandibular molars considering the tactile sensibility as a reference. The mesial canals (n = 22) of human mandibular molar teeth were used, and the first instrument to bind to the working length was determined after preflaring and crown-down shaping. Digital images of the root apex were acquired and a single examiner determined the contact of the file with the walls using Image J software. The results showed that the file was in contact in 47.83% and 31.71% in the MB and ML canals, respectively. When the apexes are fused, the average was 40.03%. A descriptive analysis showed that the first apical file did not touch all dentin walls in any of the samples.

Influence of X-ray beam angulations on the detection of horizontal root fractures

Aims: The aim of this study was to evaluate the variation of vertical angle for detection of fractures. Materials and Methods: Twenty-five (25) single-rooted premolar teeth were divided into two groups, fractured teeth (n = 15) and non-fractured teeth (n = 10). Artificially fractured teeth were classified according to location, number of fragments, and direction of fracture line: Horizontal, oblique, or complex. The tooth fragments were juxtaposed with cyanoacrylate, and the specimens (fractured and non-fractured) were placed individually in the dental alveolus of a human jaw with the aid of silicone rubber impression material and submitted to eight periapical radiographs in a digital sensor with a vertical range of 10 degrees (−40, −30, −20, −10, 0, +10, +20, +30). Three examiners evaluated the characteristics of the fractures and their correlation with the radiographic diagnosis (perceived or not) by varying the vertical angle. Statistical Analysis: Descriptive analysis was performed through the analytical comparison and Kappa test inter-examiner. Results: Among the three examiners, inter-examiner Kappa value was 0.536. The radiographic identification of root fracture in the 15 prepared samples was 60% (nine) at angle 0, and at the angles of +10, −10, and −20, it was less than 50%. Conclusions: Multiple radiographs with variations of vertical angle are fundamental to facilitate the diagnosis of horizontal root fractures in premolars.