SEARCH · PubMed Health

Results for “Tooth Apex”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79Linked to original sources

PubMed1995

Importance of anatomic variables in endodontic treatment outcomes: case report.

Surgical endodontic treatment was performed after a large periradicular lesion failed to resolve following nonsurgical intervention. The subsequent periradicular surgery resulted in healing with scar formation. Assessment of the resected root apex revealed a complex anatomy. The ramifications of these anatomical findings and the periradicular tissue response in healing are discussed relative to prognosis and ultimate treatment outcomes.

Adult↗

PubMed1990

Anatomy of the root apex and its histologic changes with age.

There were 87 vital and 24 nonvital teeth for a total of 111 specimens from 47 patients. The specimens were prepared to a thickness of 500 microns with a Buehler Isomet Bone Saw. Distances were measured and recorded with a Bioquant II Image Analysis System. The mean age of the patients was 48.9 years. The median age was 52 years. The range was 51 years, with a maximum of 77 years and a minimum of 26 years. There is a positive correlation, which could not have occurred by chance, that as age increases the deviation and the width of the foramen opening both increase. This increase appears to be a result of apical cemental thickening that occurs as the patient ages. The tissue in the apical area seems to be capable of generating additional cementum as the tooth ages. The cementodentinal junction width, or most apical extent of the dentin, remains constant.

Adult↗

PubMed2001

Finite element tension analysis of the supporting tissues of a maxillary canine.

INTRODUCTION: The distribution of masticatory load on the teeth and the arising force tensions in them are factors that determine the origine of destructive processes in their periodontium. The development of mathematical models and application of new computer technologies make possible their precise study. They are still not thoroughly studied. PURPOSE: To study the tensions, originating in the periodontium of a canine tooth during occlusal load by the modern method of finite elements (MFE). MATERIALS AND METHODS: A three-dimensional model of a maxillary canine is built by MFE containing 304 finite elements with six varieties of geometrical form, linked in 1409 nodes. It is supposed that the tooth is fixed firmly to the outer surface of the periodontal membrane to the alveolar bone and is loaded in the lingual wall by a force perpendicular to its longitudinal axis and directed from the lingual to the vestibular wall. RESULTS: As a result of the calculations according to MFE the tension state of dental tissues is calculated for diferent degrees of destruction of the alveolar bone. It was established that with the increase of destruction of the alveolar bone for one and the same masticatory load, the tensions in the periodontal membrane also increase. The maximal tensions act in the apex of the root and around the clinical neck of the teeth. CONCLUSION: The results obtained provide precise information of distribution of force tensions in the periodontium of maxillary canines during occlusal load. They serve as a serious theoretical base for future investigations.

Cuspid↗

PubMed1988

Correction of mucosal defects of periapical origin with periodontal surgical techniques.

Periapical lesions usually heal after successful root canal therapy. Persistent apical-oral communications may be due to anatomic and pathologic features that were originally linked to the endodontic cause of the lesion. One such factor is close proximity of the root apex to the oral mucosa. These defects necessitate corrective surgical intervention similar to techniques used in periodontal surgery. Four cases involving young female patients are described. These defects occurred in teeth that did not complete their maturation before necrosis of the pulp set in.

Adolescent↗

PubMed1993

Clinical observations on a newly designed electronic apex locator.

The introduction of alternative electronic principles and circuitry has produced the next generation of electronic apex locators, which have fewer clinical limitations and greater ease of use, on a routine basis, than their predecessors. The history of how the electronic apex locator was developed over the past 30 years and the limitations of the machines designed on earlier principles are reviewed. Clinical examples of root canal systems measured using a newly-designed, frequency-dependent apex locator are presented in order to illustrate the spectrum of cases that can be read. All measurements were made on canals irrigated previously with electro-conducting solutions, which would have made readings from earlier machines problematic. Single-rooted and molar teeth as well as teeth with vital tissue in the root canal system or with necrotic pulp tissue and periapical lesions have been treated with equal ease and results. The electronic apex locator is being advocated to supplement instrumentation technique and to improve the identification of the apical terminus of the root canal system. The routine use of these devices is advocated to ensure an accurate placement of root canal fillings rather than to eliminate the need for radiographs.

Dental Pulp Cavity↗

PubMed1994

Study of the apices of human permanent teeth with the use of a scanning electron microscope.

The apical region of the roots of 38 maxillary incisors, 25 mandibular incisors, 29 maxillary second premolars, 92 mandibular first and second premolars, 12 maxillary first molars, and 17 mandibular first molars were prepared and studied with the use of a scanning electron microscope. The number and size of the main apical foramina, their distance from the anatomic apex, and the existence and size of accessory foramina were recorded, summarized, and statistically analyzed. More than one main foramen was observed in all groups except for the palatal root of maxillary molars and the distal root of mandibular molars. Accessory foramina were also observed in all groups of teeth. The distal roots of mandibular molars had the largest size main foramen (mean value, 392 microns), whereas the maxillary premolars had the largest accessory foramina (mean value, 53.4 microns) and the most complicated apical morphologic makeup. The distance of the main foramen from the anatomic apex never exceeded 1 mm. The highest values were observed at the mandibular incisors (978 microns), the distal root of mandibular molars (818 microns), and the upper premolars (816 microns). All values showed satisfactory fitting to normal distribution.

Chi-Square Distribution↗

PubMed1982

Endodontic abutments and complete dentures.

In this in vitro study, 90% of maxillary single-rooted teeth, 89% of maxillary multirooted teeth, 82% of mandibular single-rooted teeth, and 92.5% of mandibular molars had root canals that terminated short of the radiographic root apex. dimensional variability was considerable. Mean measurements provide acceptable levels for underfilling canals and dictate generally applicable levels at which root canal fillings are best terminated. These measurements indicate that, when filling maxillary teeth and mandibular molars, the termination point of the filling should be approximately 0.89 mm short of the radiographic root apex. When filling mandibular single-rooted teeth, the terminal point of the filling material should be approximately 0.69 mm short of the radiographic root apex. Complete overdentures are a valuable alternative to extraction and conventional denture placement. The nonvital teeth that are used for stability, retention, preservation of alveolar bone, proprioception, and psychological support are of critical importance. Failure in endodontic selection and procedure immediately negates the concept of overdentures.

Adult↗

PubMed1980

Accessory medial pterygoid muscle.

A previously undescribed accessory medial pterygoid muscle occurred uniformly in the dissection room population studied. The origin extends from the superior margin of the pterygoid plate and skirts medially of foramen spinosum and ovale, finally terminating on the carotid canal rim. The flat triangular muscle descends to insert its apex into the medial surface of the medial pterygoid muscle about 1 cm below its exit from the pterygoid fossae. Histologic examination confirmed striated muscle. Independent innervation arises from the medial surface of the mandibular nerve trunk just below the foramen ovale and enters the accessory medial pterygoid lateral surface at about the upper third, centrally. Muscle function is suggested as a discriminating action, rein-like in nature, probably corresponding to Bennett movement. Variation in size of this muscle may also explain the range observed for Bennett movement. The dental occlusal action field is suggested to be the buccal aspect of the last molar tooth.

Adipose Tissue↗

PubMed1989

Pulpal healing after luxation injuries and root fracture in the permanent dentition.

Pulpal healing patterns were studied in a clinical material of 637 luxated and 95 root-fractured permanent incisors followed routinely for up to 11 years. It was found that pulpal healing patterns could generally be divided into 3 groups according to the degree of injury sustained by the pulp: little, moderate or severe. Thus after luxation injuries, pulp survival could be without radiographic change (PS), with pulp canal obliteration (PCO) or nonhealing (pulp necrosis (PN]. After root fracture, similar healing patterns could be observed: healing by hard tissue union of fragments (HT), by connective tissue union of fragments (CT) or by nonunion due to interposition of granulation tissue between fragments (GT) resulting from PN of the coronal fragment. In both trauma situations, healing or nonhealing could be determined by type of luxation injury, stage of root development and type of fixation used (forceful application of orthodontic bands vs. passively applied acid-etch fixation). Pulpal healing complications (PN or GT) were based on clinical findings (coronal discoloration, loss of pulpal sensibility) and radiographic findings (resorption processes of the lamina dura at the root apex or at the level of the root fracture). However, in both injury groups the same changes could also be seen to be intermediate steps in the pulpal healing process. Based on findings from these studies, hypotheses for the mechanics of pulpal healing are proposed as well as guidelines for acute and later treatment of dental luxations, root fractures and the diagnosis of healing complications.

Dental Pulp↗

PubMed2003

Lymph drainage in the human dental pulp.

We investigated which structural components are responsible for maintaining interstitial fluid equilibrium in the pulpal tissue, for which the existence of an effective lymph drainage is postulated. There have been only a small number of investigations on pulpal lymph tissue. Therefore, we decided to perform a detailed structural analysis. Twenty vital, healthy teeth that had to be extracted for orthodontic reasons were immersed in Patent Blue for 10 to 15 minutes after opening the pulpal cavity. They were then extracted and the dental pulps were opened by cleavage of the surrounding hard tooth structure. Subsequently, the specimens were prepared for light and electron microscopic investigation. A clear blue ring of stain was detected by light microscopy in Weil's zone in the coronal region of the pulp, the cell-rarefied layer surrounded by the odontoblasts. No dye deposition was observed in the apical part. However, using transmission electron microscopy, capillary structures with typical morphological characteristics of lymphatic vessels were found apically. The coronal part of the pulp did not reveal any such vascular structures. It may be concluded from these findings that the lymph in the coronal region is collected in interstitial tissue clefts and drained towards the apex, whence it is further transported via lymph capillaries.

Adult↗

PubMed1996

Apical root resorption in orthodontically treated adults.

This study analyzed the relationship in orthodontically treated adults between upper central incisor displacement measured on lateral cephalograms and apical root resorption measured on anterior periapical x-ray films. A multiple linear regression examined incisor displacements in four directions (retraction, advancement, intrusion, and extrusion) as independent variables, attempting to account for observed differences in the dependent variable, resorption. Mean apical resorption was 1.36 mm (sd +/- 1.46, n = 73). Mean horizontal displacement of the apex was -0.83 mm (sd +/- 1.74, n = 67); mean vertical displacement was 0.19 mm (sd +/- 1.48, n = 67). The regression coefficients for the intercept and for retraction were highly significant; those for extrusion, intrusion, and advancement were not. At the 95% confidence level, an average of 0.99 mm (se = +/- 0.34) of resorption was implied in the absence of root displacement and an average of 0.49 mm (se = +/- 0.14) of resorption was implied per millimeter of retraction. R2 for all four directional displacement variables (DDVs) taken together was only 0.20, which implied that only a relatively small portion of the observed apical resorption could be accounted for by tooth displacement alone. In a secondary set of univariate analyses, the associations between apical resorption and each of 14 additional treatment-related variables were examined. Only Gender, Elapsed Time, and Total Apical Displacement displayed statistically significant associations with apical resorption. Additional multiple regressions were then performed in which the data for each of these three statistically significant variables were considered separately, with the data for the four directional displacement variables. The addition of information on Elapsed Time or Total Apical Displacement did not explain a significant additional portion of the variability in apical resorption. On the other hand, the addition of information on Gender to the information on the four directional displacement variables yielded an R2 value of 0.35, which indicated that these variables taken together could account for approximately a third of the observed variability in apical resorption in this sample.

Adult↗

PubMed1976

Fine structure of differentiating ameloblasts in the kitten.

The fine structure of differentiating ameloblasts was studied in the lower second molar of 1-week-old kittens after perfusion fixation with and without subsequent decalcification. The differentiation zone was divided into three phases. In Differentiation 1, ameloblasts are about 27 mum long and face an uninterrupted basal lamina. The predentin adjacent to the basal lamina contains a few collagen fibrils oriented mainly at right angles to the ameloblast surface. The specialized predentin forms a well-defined layer, up to 1.5 mum thick, referred to as the junctional layer. In Differentiation 2, ameloblast processes extend through the basal lamina and the thickness of the junctional layer. The processes consist of cytoplasmic sheets forming a honeycomb-like network. Dentin starts to calcify after process-formation is underway. Two distinct types of odontoblast processes, having different shapes and contents, come in contact with the ameloblasts and push into the ameloblastic layer. In Differentiation 3, stippled material appears in the extracellular spaces between ameloblasts. Later, stippled material-like substances appear in the predentin close to the ameloblast apex and close to odontoblast processes within the dentin. Ameloblasts now are up to 40 mum high. Enamel secretion starts in small circumscribed areas which gradually enlarge, leading to the disappearance of the ameloblast processes. These findings are compared with results obtained in other species, including man, and their possible functional significance is discussed.

Ameloblasts↗

PubMed1990

Localization and identification of root canal bacteria in clinically asymptomatic periapical pathosis.

Twenty-one teeth with clinically asymptomatic periapical pathosis (class 3) were extracted and the isolation, identification, and localization of bacteria in the root apex were examined. Mixtures involving several bacteria were isolated from more than 60% of the cases. Scanning electron microscopy revealed bacterial masses to be associated with the apical part of the root canal, but not with the area of apical foramen or on the surface of root apex. Our results indicate that the bacteria in class 3 cases may be derived from organisms which colonized before or during endodontic treatment, but not from anachoresis. The bacteria-positive cases of asymptomatic periapical pathosis have the potential to progress to symptomatic periapical pathosis.

Actinomyces↗

PubMed1998

Nickel-titanium versus stainless-steel finger spreaders in curved canals.

Placement of endodontic spreaders to within 1 to 2 mm of the root canal working length has been advocated for optimum gutta-percha obturation. Due to their stiffness, stainless-steel (SS) spreaders will often fail to achieve this position in curved canals. Newly marketed nickel-titanium (NiTi) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. Seventy mesial and distal mandibular molar canals were instrumented to a #35 master apical file size. Measurements of the canal curvature were made from preoperative radiographs. Canal curvature angles ranged from 0 to 51 degrees. The teeth were placed in a radiographic mount to ensure a constant focal length, and postoperative radiographs were exposed with comparably sized SS and NiTi spreaders inserted into each prepared canal. Measurements of spreader tip to apex distance were made with a micrometer to the nearest 0.02 mm on the radiographs. Using a t test for paired samples, it was shown that NiTi spreaders penetrated to a significantly greater depth than SS spreaders in curved canals (p < 0.001).

Dental Instruments↗

PubMed2002

Straight line access and coronal flaring: effect on canal length.

The object of this study was to determine if canal length is altered as a result of straight-line access (SLA) and coronal flaring (CF). Selected were 86 canals of extracted molars and premolars from two groups: straight or severely curved (Schneider curvature <5 degrees and >20 degrees). The reference cusp tip and root-end were flattened to produce reproducible measurements. A #10 file was placed such that the tip extended slightly beyond the apex, with the handle on the referenced cusp. The amount of file protrusion was measured with a stereomicroscope. Then, SLA and CF were performed and the corresponding file replaced to the same coronal reference position. Apical file protrusion was measured again. The change in canal length was determined by the difference in the pre- and post-SLA/CF measurements. A Wilcoxon signed rank test statistically verified that there was a measurable, significant (p < 0.001) change in canal length after SLA and CF. The mean change overall was slight, with a decrease of 0.17 mm. Severe curvature had a slightly greater, significant effect on the amount of change. Tooth type had no significant effect. Changes in working length from SLA and CF, although statistically significant, were very small and clinically unimportant.

Bicuspid↗

PubMed1991

Applicability of an image analysis system in alveolar bone loss measurement.

Clinical and epidemiological studies in the field of periodontics and endodontics often utilize radiographs to monitor or measure the changes in bone structure and density. Periodontal bone loss or gain can be quantified on a radiograph by measurement of the distance between the bottom of the bony pocket and the apical contour of the involved tooth. The objective of this investigation was to study the accuracy of an image analysis system (IAS) to measure changes in height of the interproximal crest on radiographs. Artificial bone lesions were introduced in a dissectioned part of a human mandible. The distances between crest and apices were measured with a micrometer (MM). Radiographs were produced with horizontal and vertical deviations of 10 degrees. The radiographs were digitized and processed by computer. The landmarks in the digital image were enhanced mathematically and by histogram-based thresholding. The depth of the introduced defect was increased 6 times, followed by the measurement procedure. The IAS produced measurements of crown-apex distances with an accuracy of 0.066 to 0.358 mm. Repeated crest height measurements were recorded with an accuracy of 0.112 to 0.184 mm. Both the histogram-based binarization and the ellipse-fitting type of contour detection could be applied precisely. Misangulation errors during radiographic exposure of 10 horizontal or vertical did not statistically significant influence the IAS-measurements. The IAS can be applied in clinical trials and follow-up studies.

Alveolar Bone Loss↗

PubMed1992

Radiographic "working length" revisited.

The desired "working length" for the biomechanical preparation and resultant obturation of the root canal system is one of the most important phases of endodontics. Traditionally, radiographs are used to confirm working length of the root length and to evaluate the subsequent obturation of the root canal system. This study attempts to determine if radiographs are an accurate method of root length determination in a period when electronic apex locators are proposed as their replacement. Eight-seven vital and 24 nonvital teeth were accessed and files placed to and the radiographic working length before the file and teeth were extracted for sectioning. Results showed that the radiographic distance of the file from the apical vertex was 0.7 mm shorter than the actual file position. This discrepancy can lead the clinician to try to get closer to the radiographic apex, when in reality the end of the file is closer to the vertex than is suspected. The average distance short of the vertex as established by Kuttler should be increased to lie between 1.5 and 2.0 mm from the apical vertex to prevent overfilling the root canal.

Adult↗

PubMed2002

Dental CT evaluation of mandibular first premolar root configurations and canal variations.

OBJECTIVES: Routine dental CT scans were used to describe mandibular first premolar root configurations and canal variations. STUDY DESIGN: One hundred twenty dental CT examinations were evaluated for mandibular first premolar root configurations and canal variations regarding shape of root and root canal, incidence of multiple canals, and level of bifurcation. RESULTS: A total of 17 teeth in 12 patients showed mesial invagination of the root of the mandibular first premolar. One root displayed 3 canals with 3 apical foramina. In 2 teeth, a single canal divided into 2 canals, but merged into 1 apical foramen. One root showing 2 root canals finally divided into 2 roots near the apex. Thirteen roots had 2 canals and 2 apical foramina. The distance from the cementoenamel junction to the level of bifurcation was between 4 and 13 mm (mean, 7.4 mm). CONCLUSION: The occurrence of incidentally found mandibular first premolar root variations should be an important component of dental CT reports.

Bicuspid↗