PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Tooth Root”

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 559 records · Page 31Linked to original sources
PubMed2003

Determination of the mechanical properties of the periodontal ligament in a uniaxial tensional experiment.

BACKGROUND: The periodontal ligament is a soft connective tissue which joins the tooth root to the alveolus and thus provides for anchorage of the tooth in the alveolar bone. Due to its composition of elastic and viscous components, this tissue displays viscoelastic material properties. In a previous study [4], in vitro experiments revealed typical viscoelastic material properties of the periodontal ligament in samples from pig mandibles. These properties included force relaxation, hysteresis, and dependence on loading history. MATERIAL AND METHODS: Based on those experiments, a dependence of tooth displacement on loading velocity was registered in the present study and the stress-strain behavior of the periodontal ligament was examined until the tissue ruptured. For this purpose, segments of the periodontal ligament taken from anterior teeth from the pig mandible were tested in a purpose-developed clamping fixture in a uniaxial tensional experiment. RESULT: It was found that the initial phase of the stress-strain curve in particular was dependent on loading velocity and that the shape of the hysteresis curve was subject to a variation in loading velocity. The stress-strain behavior of the periodontal ligament was characterized, divided into several phases, and the elastic modulus of the initial and the linear phase of the curve was determined at different loading velocities. CONCLUSION: Knowledge of the material properties of the periodontal ligament is fundamental to an understanding of orthodontic tooth movement and thus to selection of an optimal force system for orthodontic treatment.

Animals↗
PubMed2002

Results of root canal treatment in dogs: 127 cases (1995-2000).

OBJECTIVE: To evaluate results of root canal treatment in dogs. DESIGN: Retrospective study. SAMPLE POPULATION: 127 tooth roots in 64 dogs. PROCEDURE: Radiographs obtained before surgery, immediately after surgery, and during follow-up examinations after surgery were evaluated by 2 individuals. Treatment was considered successful if the periodontal ligament space was normal and possible preoperative root resorption, if present, had ceased. Treatment was considered to show no evidence of failure if possible preoperative root resorption had ceased but a preexisting periapical lesion had remained the same or only decreased in size and not complete resolved. Treatment was considered to have failed if a periapical lesion or root resorption developed subsequent to endodontic treatment, if a preexisting periapical lesion had increased in size, or if possible preoperative root resorption appeared to continue after endodontic treatment. RESULTS: Follow-up time ranged from 1 to 60 months (mean, 13 months). Treatment was classified as successful for 87 (69%) roots, as showing no evidence of failure for 33 (26%) roots, and as having failed for 7 (6%) roots. The success rate was lower for canine teeth than for maxillary fourth premolar teeth. Roots with a preexisting periapical lucency or preexisting root resorption had lower success rates. The use of intracanal medication and the method and quality of obturation were not associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that root canal treatment offers a viable option for salvage of periodontally sound but endodontically diseased teeth in dogs.

Animals↗
PubMed2003

The effect of prostaglandin E2 and calcium gluconate on orthodontic tooth movement and root resorption in rats.

Possible modifications in orthodontic tooth movement (OTM) and root resorption as a result of local injections of prostaglandin E2 (PGE2) alone and with calcium gluconate (Ca) formed the aim of the present study. Twenty-four 8-week-old male Wistar rats were selected and randomly divided into three groups of eight. Both quadrants of the upper jaws of the first group of animals were used; therefore this group comprised two groups: control and normal. The upper left first molars of these eight animals were not placed under orthodontic force and received no injection, to serve as the normal group, considered for root resorption comparison only. The control group had localized submucosal injections of normal saline on the buccal side of the upper right first molar. In the third group, 0.1 ml of 1 mg/ml PGE2 was injected at the same site and the fourth group received an intraperitoneal injection of 200 mg/kg Ca (10%) in addition to the PGE2. All the injections were performed on days 0 and 7. The orthodontic appliance consisted of a closed coil spring ligated to the upper right first molar and incisor, exerting a force of 60 g during the 21-day experimental period, after which the animals were sacrificed. Palatal halves were removed for histological examination and for calculation of the amount of root resorption. Statistical analysis of data showed a significant (P < 0.05) acceleration in OTM after PGE2 injection compared with the control group. The addition of Ca reduced OTM but a significant increase (P< 0.05) was still recorded. A significant difference (P < 0.05) in root resorption was only observed between the PGE2 and normal groups. The findings show the importance of calcium ions working in association with PGE2 in stabilizing root resorption while significantly increasing OTM.

Analysis of Variance↗
PubMed2002

Numerical experiments on long-time orthodontic tooth movement.

In orthodontic treatment, teeth are moved by the use of specific force systems. The force system used depends on the patient's orthodontic situation characterized by the geometry of the tooth and the surrounding alveolar bone, which defines the position of the center of resistance. Therefore, the simulation of bone remodeling could be helpful for the treatment strategy. In this study, the optimal force system for bodily movement of a single-root tooth, with an orthodontic bracket attached, was determined. This was achieved by the use of the numerical finite element method, including a distinct mechanical bone-remodeling algorithm. This algorithm works with equilibrium iterations separated in 2 calculation steps. Furthermore, a parametric 3-dimensional finite element model, which allows modifications in the root length and its diameter, is described. For different geometries, the ideal moment-by-force ratios that induce a bodily movement were determined. The knowledge of root geometry is important in defining an optimal force system.

Algorithms↗
PubMed1988

Management of an avulsed tooth with severe root resorption.

Delayed replantation of an avulsed tooth with an open apex resulted in failure of revascularization, necrosis of the pulp and extensive external root resorption. Removal of the necrotic pulp and repeated intra-canal dressings of calcium hydroxide over a three year period arrested the inflammatory resorptive process. The process was replaced by replacement resorption leading to ankylosis and infra-occlusion of the affected tooth. As the tooth was asymptomatic, it was retained in the arch to act as a space maintainer. To improve aesthetics, the crown was recontoured using a light-cured resin.

Calcium Hydroxide↗
PubMedDate not supplied

[Histologic changes in human periodontal tissue after transplantation of teeth with completely formed roots].

Authors present the histological evolution of the periodontal tissues after complete-root teeth transplantation in human. They point out that there is a great distinction between the histological and clinical results. It is difficult to obtain the neoformation of a normal periodontal ligament. In spite of the histological failure, they obtained a good clinical result: there fore the complete-root tooth transplantation must be considered an acceptable surgical procedure.

Adolescent↗
PubMed1991

[Arch-guided tooth movement--its dynamics, efficacy and side effects].

Canine retraction on a continuous arch wire was simulated using the OMSS. The influence of wire dimension, force generating element (power chain, coil spring, powerhook, uprighting spring), bracket width and the position of the center of resistance on the effectiveness of the distalization of the canine and its side effects such as extrusion, rotation and tipping were examined. Stainless steel, nickel titanium and multi-stranded wires were tested. Employing the 0.018"-slot system, the use of an 0.016" X 0.022"-arch wire gave the best results. Comparing the NiTi coil spring with the elastic chain, the former should be preferred, because, due to its low load deflection it generates a nearly constant force over a wide range of activation. Using powerhooks or uprighting springs, a nearly bodily movement could be achieved. On the other hand, friction may increase if the uprighting is too strong. The rate of tooth movement decreases by increasing length of tooth root represented by the position of the center of resistance. Arch guided tooth movement along multi-stranded wires shows a high effectiveness, nevertheless, these wires should not be used for canine retraction because of the above mentioned side effects.

Computer Simulation↗
PubMed2001

The effects of dowel design and load direction on dowel-and-core restorations.

STATEMENT OF PROBLEM: Complications such as loosening of the dowel and core or fracture of the remaining tooth root can be influenced by many factors, including the amount of remaining dentin, direction of the occlusal load, and design of the dowel. Most stress analyses of dowel and cores were conducted without including all aspects of the restorations and supporting structures. PURPOSE: The purpose of this study was to investigate the influence of occlusal stresses on various dowel designs in a restored, endodontically treated maxillary incisor by using a 2-dimensional finite element analysis model. MATERIAL AND METHODS: A 2-dimensional finite element model was constructed in a labiolingual cross-sectional view of a maxillary central incisor, a dowel, a core, and the supporting tissues to investigate stresses in various dowel designs. As a control, a metal-ceramic crown on an endodontically treated tooth without a dowel and core was modeled. A 10-kg force was applied as follows: (1) in a vertical load on the incisal edge, (2) in a horizontal load on the labial surface, and (3) in a 20-degree diagonal load on the lingual surface. RESULTS: The use of a dowel reduced the peak dentinal stress to 75% of the magnitude of the control. When a vertical force was applied, the magnitudes of stress of the various dowel designs were similar; however, when loaded horizontally, the short dowel produced the greatest dentinal stress concentration, and the tapered dowel showed the greatest stress concentration within the cement layer. Greater deflections and higher stresses were generated with horizontal loading. CONCLUSION: The dowel and core provided little reinforcement to the remaining tooth. The direction of the functional load had a greater effect than dowel design on maximum stress and displacement. Parallel-sided dowel and cores with a length of 12 mm distributed the stress widely in the restoration and dentin, resulting in the smallest stresses.

Bite Force↗
PubMed1998

Computed tomographic features of calcifying odontogenic cysts.

OBJECTIVES: To describe the CT appearances of 4 cases of the calcifying odontogenic cyst (COC) with particular reference to the effect of varying the window settings. METHODS: Conventional radiographs and CT scans of 4 calcifying odontogenic cysts were analyzed with respect to the presence of an impacted tooth, root resorption and calcification. In addition, increased attenuation by desquamated keratin was examined by varying the window settings on CT. RESULTS: All lesions were located in the maxilla and on conventional radiographs, had unilocular radiolucency with a well-defined margin. Calcifications and inclusion of an impacted tooth were seen in all cases. Root resorption was observed in two cases, but was not prominent. On CT, calcification was detected at the periphery of the lesion and/or around the impacted tooth in all cases. Varying the window setting revealed an increased attenuation area due to desquamated keratin. CONCLUSIONS: Varying the window setting on CT is useful as a means of identifying both desquamated keratin and peripheral calcification in COC.

Adolescent↗
PubMedDate not supplied

Long-term outcomes of primary molar ferric sulfate pulpotomy and root canal therapy.

PURPOSE: The purpose of this study was to compare long-term outcomes of ferric sulfate pulpotomy (FS) and primary tooth root canal therapy (RCT) in vital pulps of deciduous molars exposed to caries lesions. METHODS: A total of 291 molars were treated in 130 children. One hundred and eighty-two molars received FS and 109 received RCT by random selection. RESULTS: At 3-year re-assessment, 29 molars (15 FS, 14 RCT) were available for clinical and radiographic examination. Two independent pediatric dentists evaluated periapical radiographs of the treated molars. Molars were classified 1 of 4 outcomes: (1) N = normal treated molar; (2) H = nonpathologic radiographic change present; (3) P(o) = pathologic change present, follow-up in 6 months; (4) P(x) = pathologic change present extract immediately. Survival analysis was applied. A good level of agreement between raters was found for molars with outcome P(x) (K = 0.79). No difference in radiographic outcomes was demonstrated 3 years after treatment (chi2 = 1.4). Survival analysis demonstrated a 3-year survival probability of 0.62 for FS-treated molars and 0.92 for RCT molars. Survival of RCT molars was significantly greater than for FS molars (Wilcoxon: P = .01; log-rank: P = .02). CONCLUSIONS: RCT-treated molars demonstrated significantly greater survival than FS-treated molars 3 years after treatment.

Child, Preschool↗
PubMed1991

A one-stage calcific barrier technique in a root-fractured incisor tooth: a case report.

This paper describes the use of calcium hydroxide powder as an immediate plug before root canal obturation in the case of a root-fractured upper central incisor that had been unresponsive to 18 months of treatment to create a calcific barrier. The calcium hydroxide plug allowed both good condensation of the filling material and prevention of extrusion of the root filling material which could have been detrimental to continued healing of the fracture.

Calcium Hydroxide↗
PubMed2002

Experimental tooth movement through mature and immature bone regenerates after distraction osteogenesis in dogs.

The purpose of this study was to verify the influence of tooth movement on tooth roots and periodontal tissues when teeth were moved into mature, well-organized, and mineralized regenerate bone created after distraction osteogenesis compared with immature, fibrous, and less-mineralized bone. Six 15-month-old male beagles underwent 10 mm of bilateral mandibular distraction osteogenesis. After 2-week (group 1) and 12-week (group 2) consolidation periods, third premolars were moved distally into the regenerate bone with 100 g of orthodontic force for 12 weeks. Simultaneously, second premolars were also moved distally as controls. After completion of tooth movement, the experimental animals were killed, and their tissues were harvested for histological evaluation. When premolars in groups 1 and 2 were compared, group 1 showed higher rates of tooth movement until the eighth week of experimental tooth movement (P <.05). The amount of tooth movement was significantly greater in group 1 than in group 2 or in the control teeth (P <.05). In group 1, we observed considerable root resorption extending into the dentin, and the thickness of the dentin became approximately half that of the controls at the compression side adjacent to the distraction gap. This root resorption extended from the cementoenamel junction to the root apex. In group 2, root resorption on the compression side reached the dentin, but the root resorption was less than in group 1. These results indicated that heavy force and early orthodontic tooth movement are not recommended when teeth are moved through regenerated bone created by distraction osteogenesis, to avoid tipping and severe root resorption.

Alveolar Process↗
PubMed1989

[Use of the Preci-Horix attachment in anchoring an overlay denture].

In the case report the overdenture prosthesis replacing the subtotal edentulousness is fixed by a Preci-Horix anchorage of individual design built on the tooth roots. The matrix portion of the anchorage was built in situ into the tooth plate of the denture. This aimes at preventing the disadvantageous overloading effect of the position change due to initial sinking of the denture on the support tooth.

Adult↗
PubMed1999

Dental abnormalities associated with failure of tooth eruption in src knockout and op/op mice.

c-src knockout and op/op mice develop osteopetrosis as a result of defective osteoclast function and osteoclast formation, respectively. The mutant mice can be distinguished readily from their wild-type littermates around 10-12 days after birth because their incisors do not erupt, but the morphology of their teeth and surrounding bone has not been reported previously in detail. Histologic examination of jaws of src-mutant mice reveals unerupted, abnormal incisors within their bony crypts. The tooth roots are distorted by foci of haphazard proliferation of odontogenic epithelium associated with primitive tooth structures that strongly resemble the tumor-like lesions in humans, known as odontomas. The crowns of the incisors are fused to the adjacent bone, and the developing periodontal ligament is disordered and hypocellular. Osteoclasts are present in the bone surrounding the distorted teeth, but as in other bones in these mice they lack ruffled borders and thus do not resorb effectively. Similar odontogenic proliferation is present around unerupted incisors in op/op mice which form very few osteoclasts, but the amount is significantly less than in src mutant mice. Molars fail to erupt in both types of mutant mice, but they are not accompanied by aberrant odontogenic proliferation. These findings and previous reports of similar abnormalities in jaws from op/op rats suggest that failure of incisor eruption and associated proliferation of odontogenic epithelium in osteopetrotic rodents are a direct result of defective osteoclastic bone resorption.

Animals↗
PubMedDate not supplied

A histological study on the effect of different periods of orthodontic force on the innervation and dimensions of the cat periodontal ligament.

Using light microscopy, the numbers of myelinated axons in the periodontal ligament of the cat mandibular canine were counted after orthodontic forces had been applied for either 3 days or 12 weeks, and also 8 weeks after removal of a force that had been applied for the previous 12 weeks. After 3 days no significant changes in axon number were recorded, but after 12 weeks there were significantly fewer myelinated axons in the periodontal ligament of the experimental teeth than in the control teeth. This reduction was not reversed after an 8 week recovery period. The width of the ligament was measured in an attempt to correlate regions of nerve fibre degeneration with areas of compression or tension, and the tooth root circumference was measured to assess the extent of any root resorption. It appeared that axon degeneration occurred both in areas of compression and tension. Root resorption had occurred after 12 weeks of applied force and there was no significant change after the 8 week recovery period. These findings support the view that nerve injury occurs as a result of orthodontic force and may possibly be permanent.

Animals↗