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At least 1,549 records · Page 86Linked to original sources
PubMed2002

Numerical computation of impedances of a human tooth for estimation of the root canal length.

Alternative current (ac) current conduction through a human tooth has been investigated through numerical simulation. Numerical calculation of impedance between the file (electrode) inserted in the root canal of the tooth and the outer electrode enables investigation of the impedance method used in dentistry for evaluation of the root canal length. Simulations confirm the improved sensitivity of the impedance method using the results of multiple frequency measurements.

Algorithms↗
PubMed2003

Oral diseases and conditions in community-living older adults with and without dementia.

This study compared the prevalence and experiences of oral diseases and conditions, as well as tooth loss and retained root status, in community-dwelling older adults with and without dementia. Dental examinations were conducted at baseline and at one-year for randomly selected samples of 116 dentate community-living older adults with dementia and a comparable group of 116 adults without dementia. Participants with dementia had significantly higher experiences of oral diseases and conditions at baseline and one-year compared with participants without dementia: decreased use of dentures; increased prevalence of denture-related oral mucosal lesions; increased plaque accumulation; increased prevalence and experiences of coronal and root caries; and increased numbers of decayed retained tooth roots. These higher experiences of oral diseases and conditions were related to dementia severity, not to specific dementia diagnoses. Participants with dementia already had a compromised oral health status when admitted into institutional long-term care between baseline and one-year; of concern were the high plaque levels on the natural teeth of the group of institutionalized participants with dementia.

Aged↗
PubMed2002

Root and canal morphology of Thai mandibular molars.

AIM: To investigate the root and canal morphology of 351 mandibular permanent molars collected from an indigenous Thai population. METHODOLOGY: The cleaned teeth were accessed, the pulp dissolved by sodium hypochlorite under ultrasonication and the pulp system injected with Indian ink. The teeth were rendered clear by demineralization and immersion in methyl salicylate. The following observations were made: (i) number of roots and their morphology; (ii) number of root canals per tooth; (iii) number of root canals per root; (iv) root canal configuration in each root using Vertucci's classification, with additional modifications; and (v) presence and location of lateral canals and intercanal communications. RESULTS: Of 118 mandibular first molars, 13% had a third disto-lingual root. In three-rooted teeth, 80% of the main distal roots and 100% of the disto-lingual roots had type 1 canal systems. Of 60 mandibular second molars, 10% had C-shaped roots, the majority of which had type 1 (33%) or type IV (33%) canal systems. Of 173 third molars, 68% had two separate roots, 20% had fused roots and 11% had a single C-shaped root; the majority had two canals (61%). CONCLUSIONS: This study suggests that Thai molars exhibit features of both Caucasian and Chinese teeth.

Asian People↗
PubMed2003

Bilateral buccal radicular groove in maxillary incisors: case report.

AIM: To present the rare localization of a radicular groove on the buccal aspect of a tooth and to discuss the pathology and management of the concomitant endo-periodontal defect. SUMMARY: Bilateral buccal radicular grooves were found on the maxillary central incisors of a 60-year-old female Caucasian. One groove was associated with deep local pocketing resulting in pulp necrosis and the formation of a periodontal-endodontic lesion. After endodontic treatment of the affected tooth, periodontal surgery was performed during which an apicoectomy was carried out on the root-filled tooth. Both the buccal grooves were removed by grinding, the roots were planed with curettes and a guided-tissue regeneration technique applied using amelogenin (Emdogain, Biora, Sweden). Following a period of 2 years, re-examination showed excellent healing with the complete elimination of the periodontal pocket on both incisors and significant radiographic evidence of bone regeneration. KEY LEARNING POINTS: Deep radicular grooves can predispose to pulp necrosis and the establishment of combined periodontal-endodontic lesions. Evaluation of clinical signs and appropriate diagnostic tests are of paramount importance in order to prevent incorrect diagnosis and treatment. Endodontists must be capable of performing advanced periodontal regeneration techniques during endodontic surgery.

Alveolar Bone Loss↗
PubMed1991

Patterns of initial tooth displacements associated with various root lengths and alveolar bone heights.

The present study was designed to investigate the nature of initial tooth displacements associated with varying root lengths and alveolar bone heights. A three-dimensional model of the upper central incisor was developed for the finite element analysis. Tooth displacements were determined at various levels of the tooth and the apicogingival levels of the center of resistance and centers of rotation were calculated. The results showed that moment-to-force values at the bracket level for translation of a tooth decreased with shorter root length and increased with lower alveolar bone height. In addition, apicogingival levels of the center of resistance shifted more gingivally to the cervix, or the alveolar crest with a shorter root. Alveolar bone loss also shifted the center of resistance toward the alveolar crest, whereas its position was more apical relative to the alveolar bone heights exhibited very slight changes in both cases. The centers of rotation from a single force varied substantially with a short root and alveolar bone loss. However, the relative distances of the centers of rotation from the alveolar crest in comparison with the alveolar bone heights were constant at 0.4 mm, with variations in the root length and alveolar bone height. Because this study showed that root length and alveolar bone height affect the patterns of initial tooth displacements both in the center of resistance and the centers of rotation and also in the amount of displacement, forces applied during orthodontic treatment should take into consideration the anatomic variations in the root length and alveolar bone height so as to produce optimal and desired tooth movement.

Alveolar Process↗
PubMed1980

Tooth eruption: evidence for the central role of the dental follicle.

The roles of the gubernaculum dentis, root formation, tooth crown and dental follicle in prefunctional eruption of a mandibular premolar have been studied in nine beagle dogs by radiographic and histologic evaluations of the effects of surgical ablation or removal of these structures on tooth eruption. The dental follicle was the only one of these structures required for the coordinated enlargement of the eruption pathway and formation of bone in the base of the bony crypt, the radiographic and histologic hallmarks of tooth eruption. These data, together with the topographic relationships of the dental follicle to areas of localized bone resorption and formation, are interpreted to mean that the dental follicle may influence, if not coordinate, these processes in tooth eruption.

Alveolar Process↗
PubMed2004

The effect of Emdogain gel on periodontal healing in replanted monkeys' teeth.

OBJECTIVE: We sought to histologically evaluate the effect of Emdogain gel on periodontal healing in monkeys' teeth undergoing delayed replantation. Study design Mature monkey teeth simulating avulsion were endodontically treated before extraction. Negative control teeth (group N = 10 roots) underwent immediate replantation, whereas the rest were bench-dried for 1 hour and treated in one of the following ways before replantation: the positive control teeth (group P = 12 roots) had no further treatment; group C teeth (4 roots) had the periodontal ligament removed; group D teeth (10 roots) were treated with Emdogain gel; group E teeth (6 roots) had the periodontal ligament removed before the application of Emdogain gel; and group F teeth (7 roots) had the periodontal ligament removed, the root surface conditioned, and Emdogain gel applied. Periodontal healing was evaluated after 16 weeks by undertaking histomorphometric analysis. RESULTS: The Kruskal-Wallis and Mann-Whitney U tests revealed that group N teeth had a statistically higher occurrence of complete healing than did all other groups, whereas group P was not significantly different in any of the healing categories from D, E, and F, the groups in which Emdogain gel was used. Group C teeth had a significantly higher occurrence of replacement root resorption than did the teeth in groups P and F-but were not significantly different from teeth in groups D and E. CONCLUSION: Emdogain gel did not appear to significantly reduce replacement resorption in monkeys' teeth that had undergone delayed replantation.

Acid Etching, Dental↗
PubMed1999

Comparison between a short and a conventional blade periodontal curet: an in vitro study.

This in vitro study was done to compare a short-blade, long-shank (test) curet designed for deeper pockets of incisors and a conventional Gracey 1/2 curet regarding (a) their ability to remove root surface material at different pocket depths, and (b) their effect on root surface roughness. 2 groups of 12 senior dental hygiene students used either the randomly assigned test or conventional curet for a defined period on maxillary and mandibular incisors in a cross-over experimental design. Extent of root debridement was determined by assessing the removal of black enamel paint on root surfaces within pockets using a computerized video routine and root surface roughness measured using a profilometer. When each surface of the root was analyzed separately at 2-mm increments, the test instrument exhibited superior material removal on all surfaces at the 4-6 mm CAL (p-values<0.001). However, the test curet caused a rougher surface than the conventional curet on all surfaces (p<0.001), with a mean difference of 0.27 microm. While it is assumed that the ability of the test instrument to debride the root surface of deeper pockets more thoroughly is clinically more important than the rougher root surfaces it produces, this can only be assessed by further studies in vivo.

Analysis of Variance↗
PubMed2002

Effects of root canal sealers on vertical root fracture resistance of endodontically treated teeth.

The aim of this study was to compare vertical forces at fracture of endodontically treated mandibular incisors obturated with different types of root canal sealer. Four groups of 10 teeth each were tested; group 1 served as positive and negative controls (five teeth each), and groups 2, 3, and 4 were obturated by lateral condensation with gutta-percha and AH Plus, Tubliseal, or Ketac-Endo, respectively. All teeth were loaded vertically using a plugger tip inserted into the canal space until fracture occurred; the load at fracture and the pattern of fracture were recorded. Statistical analysis was performed using a one-way analysis of variance and post hoc Scheffé test at the 95% level of confidence. Force at fracture of roots obturated with Ketac-Endo was significantly higher than those obturated with AH Plus and Tubliseal. Most fracture lines were in a buccolingual direction. The results suggested that Ketac-Endo strengthens endodontically treated roots and may be used for weak roots, which are likely to be susceptible to vertical root fracture.

Analysis of Variance↗
PubMed1994

Effects of the Nd:YAG laser and combined treatments on in vitro fibroblast attachment to root surfaces.

The purpose of this in vitro study was to evaluate the effects of the Nd:YAG laser either alone or in combination with root planning or air-powder abrasive treatment on fibroblast attachment to non-diseased root surfaces. 28, 4 x 4 mm root specimens and four disc-shaped root specimens 6 mm in diameter were obtained from unerupted 3rd molars. The root segments were randomly assigned to 4 treatment groups: (1) control; (2) laser-only treated; (3) laser treated followed by root planning; (4) laser treated followed by air-powder abrasive treatment. Laser-treated root specimens were exposed for 1 min with the Nd:YAG laser calibrated at an energy setting of 75 mJ at 20 pulses/s using a 320 microns contact fiber. The contact fiber was held parallel to the root segments and the root segments were kept moist with distilled water. Following the prescribed treatments, the root specimens were incubated with fibroblast cultures and then prepared for SEM examination. Results of cell counts of fibroblasts attached to specimens within each treatment group yielded the following means and standard deviations: control groups, 181.64 +/- 44.74; lased only, 78.57 +/- 21.35; lased and root planed 125.35 +/- 26.13; and lased followed by an air-powder abrasive, 177.28 +/- 55.71. Application of ANOVA followed by the Dunn Multiple Comparison test revealed significant differences (p < 0.01) in the number of attached cells between the control and laser-only treated groups; and between the laser-only and laser/air-powder abrasive treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed2000

Management of wide open apices in non-vital permanent teeth with Ca(OH)2 paste.

A retrospective study on 15 non-vital immature incisor teeth was done using Ca(OH)2 Pulpdent paste. A success rate of 100 percent was achieved within one year. The variables influencing the time taken for apexification were also evaluated. The teeth were followed up to a period of 24 months. It was found that older children having narrow open apex had a shorter treatment time than the younger children (NS); teeth without periapical infection showed some amount of root growth and closing of apex that was faster than those with periapical infection (p < 0.001). The calcified bridge formed following apexification is a porous structure. This investigation provides information about the time taken and procedure required to achieve apical barrier formation in non-vital immature incisors.

Adolescent↗
PubMed2001

Primary triple teeth: histological and CT morphological study of two case reports.

The macromorphology and micromorphology of two specimens of primary triple teeth using histological and CT analysis approach is analyzed. A single morphological pattern of triple teeth has been found and described: three nearly separate crowns with three separate pulp chambers, and three joined roots with three connected root canals. The characteristic triple teeth appearance occurred because a labial supernumerary tooth is the junction element between two teeth of normal series: the central incisor on the mesial side and the lateral incisor on the distal side. Primary triple teeth suggest an idiopathic abnormality in the distribution of the dental material originated very soon in the dental development. They can be considered as an early double fusion between three tooth germs, initially separate but in close proximity and developing synchronically.

Child, Preschool↗
PubMedDate not supplied

Analysis of dentinal stress distribution of maxillary central incisors subjected to various post-and-core applications.

This study evaluated the stress distribution on an endodontically treated maxillary central incisor restored with different post-and-core systems by using a three-dimensional finite element analysis model. Seven three-dimensional finite element models were created. Each model contained cortical bone, cancelous bone, periodontal ligament, 3 mm apical root canal filling, post-and-core and all-ceramic crowns. Two different pre-fabricated zirconia ceramic post systems, a glass fiber-reinforced post system and a titanium post system were modeled. As a control, an all-ceramic crown on an endodontically treated maxillary central incisor without a post-and-core was modeled. Each model received a 45 degrees oblique occlusal load at a constant intensity of 100 N. In each model, the ratio of Von Mises stress distribution was compared. The greatest stresses were observed in the coronal third of the roots on facial surfaces. The ratio of Von Mises stress distribution in dentin for the zirconia ceramic post (CosmoPost) and ceramic core (Cosmo Ingot), zirconia ceramic post (CosmoPost) and composite core (Tetric Ceram), glass fiber-reinforced post (FRC Postec) and composite core (Tetric Ceram), titanium post (Er post) and composite core (Tetric Ceram), zirconia ceramic post (Cerapost) and ceramic core (Cosmo Ingot), zirconia ceramic post (Cerapost) and composite core (Tetric Ceram) and the control group were 0.886, 0.889, 0.988, 0.924, 0.889, 0.893 and 1, respectively. The stress concentrations in dentin created by two different zirconia ceramic post systems were nearly the same. The zirconia ceramic post systems created slightly less stress concentration in dentin than the glass fiber-reinforced and titanium posts.

Bite Force↗
PubMed1979

[Methods for the partial preservation of teeth (hemisection etc.)].

The term hemisection, root amputation and tooth separation are defined. These methods of treatment should be employed after other proven therapeutic measures have failed and there is justification in the total situation for partial tooth preservation. Correct root canal filling of the remaining dental stumps is essential. Special indications exist in the molar region in the presence of deep parodontal disease. The technical details of the individual methods are described. Prognosis is good if the indications were correctly established.

Apicoectomy↗