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PubMed1991

Tooth length determination: a review.

Tooth length determination is a crucial step in endodontic treatment. Until the late 1970s, tooth length determination was based mainly on radiographic interpretation. The advent of apex locators, which identify the difference in the electrical resistance between the root canal and the periodontal membrane, ushered in a new era for measuring tooth length. However, the accuracy of these devices has been questioned. Pertinent literature is discussed with the aim of providing information on the development of the concept, techniques, and devices for tooth length determination.

Dental Pulp Cavity↗
PubMed2003

Buccal and coronal bone augmentation using forced eruption and buccal root torque: a case report.

The following case report describes the buccal and coronal bone augmentation around an irretrievable tooth using forced eruption and buccal root torque for immediate nonsubmerged implant placement. A mandibular left second premolar with degree 2 mobility, severe buccal bone resorption, and interproximal angular bony defects was subjected to forced eruption and buccal root torque. Five months after this process, the tooth was displaced 15 mm coronally and the root apex faced buccally. Buccal and coronal bone augmentation and soft tissue enlargement were evident at reentry surgery. This technique enabled proper implant placement in a situation where the bone was compromised.

Alveolar Ridge Augmentation↗
PubMed2005

Clinical evaluation of the centre of resistance of the upper incisors during retraction.

The aim of this study was to evaluate the movement of anterior teeth during retraction with a force applied through the assumed centre of resistance (CRe).Twenty-two subjects with a Class I or II malocclusion were included. Each subject had the two upper first premolars extracted, resulting in a symmetrical extraction space of at least 3 mm between the upper laterals and canines. The force was applied through the assumed CRe, located 9 mm gingival to the lateral tooth bracket. To examine the type of anterior tooth movement, 10 parameters were measured. A Wilcoxon test was used to determine the differences between pre- and post-retraction values, and a Mann-Whitney U-test to determine the mean differences between groups. In spite of the force application through the CRe, tipping of the anterior teeth was observed in 19 subjects and parallel movement in three patients. Consequently, the subjects were divided into two groups according to the location of the centre of rotation (CRo). In group 1 (nine cases), the CRo was located coronal to the root apex, and in group 2 (13 cases), apical to the root apex. Both groups showed a significant decrease in inclination (P < 0.01) and posterior crown movement (P < 0.01 for group 1 and P < 0.001 for group 2) of the anterior teeth. A significant posterior movement of the root apex was observed in group 2 (P < 0.001). Significant differences were found between the groups for anterior tooth inclination (P < 0.05) and root apex movement (P < 0.001). The reasons for these differences could not be conclusively determined. Even though experimental studies provide information regarding CRe location, factors such as bone support, root morphology and incisor inclination should be taken into consideration. The observation of tooth movement occurring during treatment and changes in treatment mechanics would be helpful in obtaining desired tooth movement.

Adolescent↗
PubMed1985

[The dentoalveolar junction].

A short survey on experiments carried out on human, dogs and models is presented. Special attention is paid to the periodontium. Registered deformation phenomena hint that the dentoalveolar system behaves as a reciprocally acting different elastic unit. This can be interpreted taking into account the mechanics of an anisotropic deformable matter. When the tooth is loaded, collagenous fibres of the periodontium are secondary activated to traction, in the course of which the fibrae alveolodentales apicales block dislocation of the apex radicis and not--as supposed in the past--getting out of the tooth from its alveolus.

Animals↗
PubMed1981

On the derivation of cell kinetics from histomorphology, observed in the rat incisor odontoblast.

A method to extract cell kinetic information from histomorphology is presented. Each replicating tissue is essentially an ordered structure with an origin where cells are formed and a periphery toward which they are displaced. The displacement path is called the tissue radius. The tissue variables may be studied in two domains, space and time. The first embraces all the states a cell may assume while the second specifies the cell transition rates. During steady state both domains are related linearly. These ideas are illustrated in the rat incisor odontoblast population whose life expectation is determined by the tooth wall shape. The odontoblast cell population paves the interior of the tooth wall delimiting a cone-shaped pulp. Near the root apex the dentine wall is barely visible. As one proceeds distally, the wall thickens while the pulp narrows. Pulp narrowing is associated with odontoblast cell loss whose magnitude may be deduced from the change of the pulp circumference CI(x) (x is the distance from tooth origin). The odontoblast force of mortality mu(x) may be calculated from the instantaneous perimeter change:mu(x) = - CI'(x)/CI(x); where CI'(x) stands for the derivative of CI(x). This equation serves for the construction of the odontoblast life table which may be studied in space and time.

Animals↗
PubMed2006

Interdisciplinary approach to endodontic therapy for uncooperative children in a dental school environment.

The aim of this study was to describe an interdisciplinary approach for endodontic therapy of behavior-challenging children and to report the efficacy of sedation techniques for these procedures. Sedation records of thirty-two patients who received root canal treatment were reviewed. Age at treatment in months, gender, year of treatment, tooth type, status of root maturation (open or closed apex), etiological factor(s), sedation protocol, and outcome were the variables analyzed. The collected information was entered into a computerized flowchart and the data analyzed using descriptive statistics. Midazolam in combination with meperidine or hydroxyzine were the most common protocols used (46 percent and 40 percent of the cases, respectively). Only two (6 percent) treatments were aborted due to uncontrolled behavior during sedation. We conclude that cooperation between pediatric dentists and endodontists is fundamental to achieving success when providing root canal treatment for uncooperative child patients.

Anesthesia, Dental↗
PubMed1990

[Development and significance of the cuticula dentis for the epithelial attachment].

The purpose of this study was to identify those conditions governing presence and function of the secondary cuticle (cuticula dentis) by means of a clinical evaluation (Periodontal Status, Plaque Index, Decayed-Missing-Filled-Index) as well as radiological, bacteriological (plaque swabs) and histological studies. The secondary cuticle could be demonstrated mainly in individuals with mild bone resorption and minimal loss of periodontal attachment (age 20-50 years). In most cases there was an intimate attachment of the junctional epithelium to the enamel or cementum surface. However, in most elderly subjects (older than 50 years) the secondary cuticle was found only in fragments or was not detectable at all. In these cases the junctional epithelium had proliferated apically (towards the apex dentis) and was only punctiformly attached to the tooth surface. Our histological findings suggested that the secondary cuticle is a secretory product of the junctional epithelium. Therefore, we assume it to be the essential structure in maintaining epithelial attachment.

Adolescent↗
PubMed2001

Histomorphometric study of the periodontal vasculature during and after experimental tipping of the rat incisor.

The periodontal vasculature encircling the entire length of the rat lower incisor was studied at the time of tipping movement and 3 months later. In 12 rats (212+/-4 g b.w.), loads (0.19+/-0.016 N) were applied to the lower left incisor in a linguointrusive direction. After 2 weeks of loading, six experimental animals were killed with the loading springs in place. The springs were removed in the six remaining rats, which were killed 12 weeks later. Six additional rats with intact teeth served as control. All incisors were fixed, demineralized, embedded in glycol methacrylate and cross-sectioned perpendicular to the long axis of the tooth. The distance of each section (2 microm) from the apex was calculated. A computerized image-analysis program was used to measure the width and area of the labial and lingual periodontal ligament to establish whether the measured segments corresponded to the compressed or expanded zones. In each cross-section, the various types of blood vessels were counted and the cross-sectional area of all venous vessels was measured. The results showed that after 2 weeks of loading (1) the general trend of vascular changes was similar under pressure and tension; (2) the large-diameter vessels were unaffected by loading; (3) the mean number of terminal arterioles had decreased significantly, while the number of capillaries and postcapillary venules had increased significantly in the apical tooth part; (4) the venous blood vessel area had decreased significantly in the apical tooth part; (5) the intensity of the vascular reaction was dependent on the degree of tissue distortion; and (6) after 12 weeks' recovery the vascular changes were still present, demonstrating a rebound effect. The findings suggest that microvascular alterations following tooth loading are not directly related to the spatial effect of loading itself and are of a much longer duration than expected.

Animals↗
PubMed1991

Material parameters and stress profiles within the periodontal ligament.

Levels and profiles of initial stress in the periodontal ligament after application of various force systems were studied. Two finite-element models, based on sections of human autopsy material, were developed to simulate one full and one partial mandible. The validity of the finite-element model was improved by identification of material parameters; the mechanical properties of the tissue were described by means of strain-gauge measurements of initial tooth movements in human autopsy material. The multiple modeling technique, in which data from a coarse global model are transferred to a more detailed one, was used to identify bone structure and boundary conditions. Parameters known to influence the results were varied to establish the validity of the finite-element model. Iterative calculation methods were used to gain stable results. However, optimizing features of the bone structure and boundary conditions did not influence the results significantly. The elastic stiffness of the periodontal ligament was determined to 0.07 MPa and tau = 0.49 (tau being the Poisson's ratio). Stress profiles were obtained for various force systems--as in tipping, translation, and root movement. As we expected, there was a marked variation in the stress distribution from cervix to apex when tipping forces were applied. Bodily movement of the tooth produced an almost uniform stress distribution; root movement produced stress patterns opposite to those observed during tipping; and masticatory forces alone produced stress patterns almost identical to those achieved by masticatory force in combination with orthodontic forces.

Adolescent↗
PubMed1989

[Experimental study on the effect of replantation of immature permanent teeth on the periapical and periodontal tissues].

Replantation and semi-rigid fixation were performed on canine immature permanent teeth, and one week after replantation the teeth were treated by root filling with calcium hydroxide. The root apex and periodontium of the teeth with replantation were examined for changes regularly during the experiment by microradiographic, fluorescence microscopic, polarizing microscopic and X-ray observation of undecalcified horizontal continual ground sections. The results obtained were as follows: 1) Immediately after replantation, root formation was observed, but its formation was found to cease at a relatively early time. No site of the root showed any inflammatory resorption. 2) The dentine of the teeth with replantation was narrow, and the whole tooth substance showed discoloration due to penetration of calcium hydroxide. 3) the periodontal space surrounding the teeth with replantation was decreased daily by new bone actively formed from the alveolar bone proper and by a thin cementum layer added on the periodontal surface. This change occurred from one week after replantation. 4) The width of the periodontal space of the teeth with replantation, which had been wider than that of a control tooth, was increased and decreased daily at the cervix and root apex and the central part of the root, respectively. 5) Collagen fibers of the periodontal membrane were present in the periodontal space of the teeth with replantation, together with regeneration of the periodontal membrane that had been cut by extraction. 6) There were no changes due to replantation in the two teeth adjacent to the tooth with replantation or the lateral jaw.

Cuspid↗
PubMed1975

On optimum orthodontic force theory as applied to canine retraction.

The study reported here was undertaken in an attempt to contribute, from a theoretical standpoint, to the knowledge and understanding of optimum force theory, particularly as it may be relevant to canine retraction. The following statements are derived from my analysis of the applicable published literature and the results of the present investigation: 1. This study lends support to the beliefs, from the findings of previous investigations, 20, 22 that the center of rotation for simple tipping is three tenths to four tenths of the distance from the root apex to the alveolar crest and that the center of resistance is at approximately midroot for the single-rooted tooth. 2. For a given distal driving force, increasing the countertipping couple from zero causes the center of rotation to "move" from a point near the apical end of the middle third of the root to the root apex and then to infinity. That is, the couple to be developed by the appliance to produce crown movement is smaller than required for bodily movement. Also, increasing the rotational stiffness of a canine-retraction appliance will result in greater inherent potential for canine root control and a greater probability of achieving bodily movement. 3. In a specific orthodontic case, an average periodontal stress value (active force divided by root area) can be used as a basis of comparison of suggested active force magnitudes among several single-rooted teeth having different root surface areas, provided all teeth are to experience the same form of displacement (for example, bodily movement). Similarly, differences in average stress magnitudes developed in the periodontium, rather than differences in root surface areas, are actually the basis for the differential force theory. 4. Clinical studies have suggested that the size of active force for bodily movement or root movement of a given tooth be two to three times that employed in simple tipping of the same tooth. Induced stress levels in the periodontium, especially at the root apex and alveolar crest locations, can be related to suggested magnitudes of aplied crown force components.

Activator Appliances↗
PubMed1987

The effect of excision of the root apex on the intrusive mobility of anterior teeth in adult monkeys (Macaca fascicularis).

Intrusive tooth mobility was recorded on anterior teeth in four adult male animals by linear variable-differential transformers. Reflection of the labial mucosa caused a significant increase in mobility at 4 N when the loading rate was slow (1 N s-1) but not when fast (100 N s-1). No significant additional increase in mobility was recorded after the apices were removed from eight incisors and canines. A further study on five incisors was made in which the displacement at 4 N load was noted half hourly during a control period of 5 or 6 h. Some weeks later, the sequence was repeated but the apices were resected after 3 or 4 h. As there was no increase in mobility for the majority of teeth following apicoectomy and, for two teeth studied in detail where there was an increase, that change was short lived; it seems that compression in the fundus of the socket is not a mechanism of importance in supporting the tooth against small intrusive loads.

Animals↗
PubMed2006

Maxillary sinusitis and periapical abscess following periodontal therapy: a case report using three-dimensional evaluation.

BACKGROUND: Maxillary sinusitis may develop from the extension of periodontal disease. In this case, reconstructed three-dimensional images from multidetector spiral computed tomographs were helpful in evaluating periodontal bony defects and their relationship with the maxillary sinus. METHODS: A 42-year-old woman in good general health presented with a chronic deep periodontal pocket on the palatal and interproximal aspects of tooth #14. Probing depths of the tooth ranged from 2 to 9 mm, and it exhibited a Class 1 mobility. Radiographs revealed a close relationship between the root apex and the maxillary sinus. The patient's periodontal diagnosis was localized severe chronic periodontitis. Treatment of the tooth consisted of cause-related therapy, surgical exploration, and bone grafting. A very deep circumferential bony defect at the palatal root of tooth #14 was noted during surgery. After the operation, the wound healed without incidence, but 10 days later, a maxillary sinusitis and periapical abscess developed. To control the infection, an evaluation of sinus and alveolus using computed tomographs was performed, systemic antibiotics were prescribed, and endodontic treatment was initiated. RESULTS: Two weeks after surgical treatment, the infection was relieved with the help of antibiotics and endodontic treatment. Bilateral bony communications between the maxillary sinus and periodontal bony defect of maxillary first molars were shown on three-dimensional computed tomographs. The digitally reconstructed images added valuable information for evaluating the periodontal defects. CONCLUSION: Three-dimensional images from spiral computed tomographs (CT) aided in evaluating and treating the close relationship between maxillary sinus disease and adjacent periodontal defects.

Adult↗
PubMed1989

Nonsurgical endodontic treatment of a tooth with double dens in dente.

A case of "double" dens in dente with an open apex and periapical lesion is reported. Nonsurgical endodontic treatment was performed. The canals were medicated for 5 months with calcium hydroxide before obturation with combined sectional and thermoplasticized warm gutta-percha. Follow-up revealed an asymptomatic patient and a reduction in size of the periapical lesion.

Adult↗
PubMed2002

Root canal length measurement in teeth with electrolyte compensation.

Electronic root canal length measurement devices have made it easier and faster to measure the root canal length of a tooth compared with the conventional radiographic method. Of these electronic apex locators, the frequency-dependent type features greater accuracy and convenience in operation. However, its accuracy is still influenced by the presence of blood and/or the various electrolytes used in root canal therapy. This study describes the development of a new frequency-dependent electronic apex locator featuring electrolyte compensation, utilising an impedance ratio and voltage difference technique to minimise the influence of electrolytes on the accuracy of root canal length measurement. The errors for distances from file tips to apical constrictions were determined in vivo with the device operating with electrolyte compensation. The measured lengths were compared with the true lengths of the extracted teeth determined using a microscope. The mean error was +0.14+/-0.27mm, and 95.2% of the measurements were within the clinical tolerance of +/-0.5mm. It was also found that the degree of accuracy was not dependent on the size of the apical foramen (p = 0.74).

Dental Pulp Cavity↗