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At least 991 records · Page 55Linked to original sources
PubMed2005

Maxillary incisor root resorption after rapid palatal expansion in Felis catus.

Root resorption after rapid palatal expansion (RPE) treatment was found in anchored teeth but has not been studied on non-anchored incisors. This study evaluated root resorption, root tipping, and root proximity of maxillary incisors after RPE treatment. Fourteen cats were divided into treated (n = 10) and untreated (n = 4) groups. The RPE treatment consisted of active, retention, and relapse phases, lasting 25, 60 and 60 d, respectively. Standardized occlusal radiographs were taken to measure tipping and root proximity before and after each treatment phase. Maxillary incisors were analysed histologically by fluorescent microscopy for root resorption. Data was analysed statistically with anova with repeated measures, t-test and Pearson's coefficient of correlation. Root resorption was confined to the first incisors and was 750-fold greater in the treated vs. the control group. Root tipping and root proximity were significantly greater (2.5- and 17-fold, respectively) in the first than in the second maxillary incisor and highly correlated with root resorption (r = -0.927 and 0.723, respectively). This suggests a cause (tipping and root proximity) and effect (root resorption) relationship. Data suggest that first maxillary incisor susceptibility to root resorption during RPE is associated with severe tipping and root proximity.

Animals↗
PubMed2005

Assessment of dental appearance following changes in incisor proportions.

This study aimed to evaluate the assessment of attractiveness of standardized changes in incisor proportions. Two original photographs, showing the maxillary anterior teeth in the frame of a smile, were computer-manipulated. From the so-produced symmetrical 'golden standard' images, two sets were constructed. Each set contained one golden standard image and seven images with different standardized changes concerning (i) width-to-length ratios of the central incisors (60-96%) and (ii) tooth-to-tooth proportions between the widths of lateral and central incisors (43-87%). The judges, consisting of three groups of individuals (24 dentists, 24 medical students, and 179 patients), ranked each photo set for attractiveness on a visual analogue scale. The width-to-length ratios were assessed as most attractive within a range of 75-85% (medical students, patients) or 75-80% (dentists), respectively. The tooth-to-tooth proportions showed the best results concerning attractive appearance within a range of 50-74% (medical students, patients) or 56-68% (dentists), respectively. No significant differences between the participant groups were found except for some extreme variations. It was concluded that a most attractive 'golden range' could be identified for both the width-to-length ratios and the tooth-to-tooth proportions of the maxillary incisors.

Adolescent↗
PubMed2006

Comparison of methods for measurement of hypoplastic lesions.

Enamel hypoplasia is a quantitative defect of enamel thickness. Methods previously used for its measurement have limitations in clinical studies. The aim of this study was to investigate new methods of measurement using image analysis. Lesions on 8 teeth affected by enamel hypoplasia were quantified from study models and impression surfaces using an image-analysis system. The measurements made included lesion area and tooth surface area; from these the proportion of tooth surface area affected was calculated. For comparison, manual measurement was performed on impression surfaces and study models, using digital callipers. Images were also acquired of lesions on 12 exfoliated teeth, and the lesion area and total tooth area were calculated. For assessment of intra-operator reliability, the +/-repeatability coefficient was calculated. Measurement of the surface of lesions direct from the exfoliated teeth gave the best results overall, followed by direct image analysis of the silicone impression.

Dental Enamel↗
PubMed1992

Growth of acellular extrinsic fiber cementum (AEFC) and density of inserting fibers in human premolars of adolescents.

The present study describes for the first time the changes of both AEFC thickness and the numerical density of collagen fibers inserting into AEFC at specified levels and sites of human premolars at different stages of development. The investigation was based on 45 premolars (25 maxillary, 20 mandibular; 25 first and 20 second), extracted from adolescents and young adults. All teeth were free of disease and presented with roots developed from 30-100% of their final length. They were prefixed in Karnovsky's fixative, decalcified in EDTA and subdivided into about 14 slices each, cut from mesial and distal root surfaces, vertical to and along the root axis. The slices were postfixed in OsO4, embedded in Epon and cut for light-microscopic study. AEFC thickness (4086 measurements) and the density of the collagenous fiber fringe (454 counts) inserting in AEFC were measured at 1, 3, 5 and 7 mm apical to the cementoenamel junction. The data obtained showed: AEFC thickness increased with age and varied between 0 and 57.5 microns. Between 9 and 17 years, cervical AEFC thickness increased in maxillary first premolars from an average of 5 to 30 microns, and in mandibular second premolars from 6 to 20 microns, i.e., AEFC grew at approximately the same rate as later in life. Depending on the differences in tooth development, AEFC on maxillary first premolars became thicker than that on mandibular second premolars. Due to the corono-apically decreasing gradient of AEFC development, its increase in mid-root regions lagged behind that in cervical regions of all teeth in people younger than about 14 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Use of an electronic apex locator in the treatment of teeth with incomplete root formation.

An electronic apex locator was used to determine length and control apical bridge formation in the treatment of teeth with incomplete root formation. Measurements were taken in 10 teeth in which apexification therapy had just started and in 11 teeth where the formation of the apical barrier was considered to be complete. In the beginning of the apexification therapy, when the apical foramen was still open, endometric measurements gave incorrect results in all instances. After apical closure had occurred and definite obturation of the root canal seemed possible, the apex locator in all teeth gave correct results and complete agreement was obtained between the radiographs and the electronic tests. Even in teeth in which complete apical closure could not be obtained, the results of electronic measurements were correct. Electronic apex locators may be used as auxilliary devices in controlling apical hard tissue closure in the treatment of teeth with incomplete root formation.

Adolescent↗
PubMed1991

Comparison between two ultrasonic units in shaping curved canals in teeth using macroradiography.

The efficacy of two ultrasonic units in shaping curved canals in teeth were compared. Twenty teeth were instrumented using the Cavi-Endo unit at a power setting 1 using the technique recommended by the manufacturer. Another group of 20 teeth received similar treatment but were instrumented with the Enac unit. The time taken to instrument each canal was recorded. The pre- and post-instrumented radiographs of the teeth of x 10 magnification were taken using a microfocal technique. The radiographs were subjected to a subtraction technique to result in composite images of the pre- and post-instrumented shapes. The canal shape and the incidence of elbows were evaluated using various measurements taken from the radiographs. The manner the dentine was removed was similar in both groups. All canals exhibited unequal removal along the canal with more dentine being removed at the coronal end. The Enac group exhibited a higher incidence of elbows which occurred further apically than those in the Cavi-Endo group. There was no significant difference between groups in the following: time of instrumentation, amount of apical and coronal canal enlargement, apical deviation and change in width at the elbow. These findings were no different from those of another study using simulated canals.

Chi-Square Distribution↗
PubMed1994

In vitro evaluation of an audiometric device in locating the apical foramen of teeth.

A new audiometric device to determine the location of the apical foramen of teeth undergoing endodontic treatment according to "the relative value method" was tested in in vitro experiments. In 96.5% of the 350 human teeth used in the experiment, the location of the apical foramen was determined within acceptable limits (0-0.5 mm). In 60 teeth, where the measurements were based on an intermittent audio signal, a point about 1 mm short of the apical foramen was located. The results were considered promising and a clinical evaluation of the device will be carried out.

Auscultation↗
PubMed1995

Morphologic criteria for root canal treatment of primary molars undergoing resorption.

The endodontic anatomy of primary molars is difficult to predict because of the balance of resorption and hard tissue deposition. In particular, the resorption causes perforating lacunae across the wall of the root, even at the furcation level, and modifies shape, dimension and position of endodontic apex. The phenomenon can be so deep as to compromise endodontic therapy. The first aim of the study was to verify if reliable criteria can be found for treatability in primary molars undergoing resorption, i.e. if it is possible to predict if perforating lacunae are present or not. The second aim of the study was to verify if other informations needed for endodontic treatment, as shape, dimension and location of the apex, and curvature of the root canal can be predicted. For the study, 80 extracted primary molars, 75 of which pulpally involved by caries, were selected. The treatability was evaluated in term of root length, root shape, dimension and shape of endodontic apex, age of the patient and X-ray index of resorption. The association between variables was performed by multiple correspondence analysis. The results suggested that root length was the most reliable criterion of the integrity of the root. The borderline of treatability was at the length of 4 mm. The position of endodontic apex related to anatomical apex, and the lingual related to the buccal root length were analyzed by linear regression analysis. The canal length was often similar to the root length (i.e. the endo and anatomical apices were very close) in lower and upper molars. However, in lower molars, if two or more canals were present in the same root, a discrepancy was observed between buccal and lingual root length. This finding was constant in first lower molars. In addition regression analysis provided a linear function between the lengths of the buccal and lingual side of the same root in lower molars. Its coefficient b was 0.73.

Analysis of Variance↗
PubMed1996

Endodontic measurements in digital radiographs acquired by a photostimulable, storage phosphor system.

Digora is a newly developed digital system for intraoral radiography utilizing photostimulable storage phosphor image plates. The aim was to test the quality of the system in respect to the visibility of endodontic files and root apices at different exposures. In teeth from five dry mandibular jaw sections, Hedstrom files no. 15 were placed with the file tip at varying distances from the apex. The specimens were covered with soft tissue equivalent material and placed behind a 2-cm thick polymethyl methacrylate cylinder filled with water. Distance from focus to image plate was 30 cm. Exposures were made at 60 kV and 7 mA at 7 timer settings from 16 ms to 1000 ms in 50% increments. All images were viewed from the monitor by each of 8 observers allowed to use available contrast enhancement facilities to obtain subjectively good image quality. Utilizing built-in measurement functions, distances from file tip and root apex, respectively, to a reference line were measured in 0.1 mm. For measurements between file tip and reference line, and root apex and reference line, there was no statistically significant difference between measurements made at the lowest exposure, compared to the second lowest exposure but there was a statistically significant difference compared to the 5 highest. Measurements at the second lowest exposure were not significantly different from those obtained at the 5 highest exposures. Interobserver variability expressed as standard deviation between observers showed the largest value for measurements obtained at the lowest exposure. The mean observed distances between the tip of the file and the root apex were calculated and showed no statistically significant differences between different exposures. We concluded that the Digora intraoral image plate system provided reliable endodontic measurements even at very low exposures.

Analysis of Variance↗
PubMed1997

Electrical impedance measurements of root canal length.

Electronic methods are now widely used during endodontic treatment for the assessment of root canal length. These commonly measure the electrical resistance or impedance between the root canal and the buccal mucosa. A number of studies have been undertaken to determine the accuracy of commercially available instruments. The aims of this investigation were to determine the electrical impedance characteristics of the root canal and periapical tissues in vivo, measure the changes relative to the distance of an endodontic instrument from the apical constriction and propose an equivalent circuit modelling the periapical tissues. The length of the root canals of 20 previously untreated teeth were determined using radiographic and electronic methods. Minimal canal preparation was carried out and measurements were made with a size 10 K-Flex file. A microprocessor-controlled LCR analyser was used to measure the electrical impedance characteristics of each root canal. The instrument measured the series and parallel resistive (RS, RP) and capacitance (CS, CP) component of the tissues at two test frequencies, 100 Hz and 1 kHz. Measurements were made for each root canal when the diagnostic file was placed at the apical constriction and repeated when the file was withdrawn to -0.5, -1.0, -1.5, -2.0 and -5.0 mm from the foramen. Readings were taken for each canal after the canal had been dried with paper points, and flooded first with deionised water and then with sodium hypochlorite. The root canals were then prepared, cleaned and obturated using standard endodontic procedures. The LCR analyser selected the series resistance component as the major measurement parameter. There was a clear increase in series resistance (RS) with increasing distance from the radiographic apex for dry canals and those containing deionised water and sodium hypochlorite. The mean resistance for dry canals was markedly higher than for those containing fluid, ranging from 22.19 k omega to 92.07 k omega in comparison with 9.32 k omega to 12.10 k omega for deionised water and from 7.46 k omega to 8.92 k omega for canals containing sodium hypochlorite. There was a marked change in the series and parallel resistive component with distance from the apex, suggesting a complex relationship between the impedance of the smear layer and bulk dentine. The impedance characteristics of a root canal were a complex electrical network comprising resistive and capacitive series and parallel elements.

Dental Pulp Cavity↗