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At least 73 records · Page 4Linked to original sources
PubMed1992

Effect of mechanical versus thermal removal of gutta-percha on the quality of the apical seal following post space preparation.

The objective of this study was to compare the effects of a flame-heated endodontic plugger, an electrically-heated endodontic spreader, Peeso reamers, and GPX burs on the apical seal when gutta-percha was removed from the root canal for post space preparation. Eighty-nine human canines were instrumented and obturated with gutta-percha and sealer to a standardized working length of 15 mm. An 11-mm segment of gutta-percha was removed from the roots in each of the four experimental groups of 20 teeth to simulate post space preparation. The teeth were immersed in India ink for 7 days and rendered transparent. The extent of linear dye leakage was measured with a stereomicroscope. There was no statistically significant difference in linear dye leakage among any of the experimental groups when 4 mm of gutta-percha remained.

Dental Instruments↗
PubMed1996

One-step apexification without calcium hydroxide.

Slow growth calcium hydroxide apexification may be clinically impractical in some instances. This case report describes a technique and rationale for single-step use of tricalcium phosphate as an apical plug in an immature permanent root. This method permitted immediate canal obturation and placement of the permanent coronal restoration. A 7-yr follow-up confirmed that this type of apexification could be successful.

Calcium Phosphates↗
PubMed1997

Evaluation for cracks associated with ultrasonic root-end preparation of gutta-percha filled canals.

Many clinicians use ultrasonics for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched human teeth for cracks before and after ultrasonic root-end preparation. Twenty matched pairs of extracted single rooted teeth were divided into two experimental groups. In group 1, root-end resection was performed on uninstrumented teeth. In group 2, root-end resection was performed after the canals were instrumented and filled with gutta-percha. All teeth in both groups received root-end preparations using ultrasonic instrumentation at low power. Two examiners evaluated the root-ends after root-end resection and again after root-end preparation using zoom magnification of 20x to 63x. The number, types, and location of cracks were mapped. There were no significant differences when gutta-percha filled roots were compared to uninstrumented roots with regard to the number or type of cracks after root-end resection or root-end preparation. In addition, there were no significant differences in the number or type of cracks following root resection and ultrasonic root-end preparation when compared to teeth with root resection alone.

Analysis of Variance↗
PubMed1998

A comparison of amounts of apically extruded debris using handpiece-driven nickel-titanium instrument systems.

One hundred single-rooted teeth were instrumented with Lightspeed, Profile .04 Taper Series 29, and NT McXIM instruments according to the recommendations of the manufacturers, and Flex-R files using the balanced force technique. Groups were comparable with respect to average curvature, canal length, and major and minor foramen size. A standard amount of irrigant was used for each tooth. Apically extruded debris and irrigant were collected and weighed. Debris was desiccated before being weighed. There were no statistically significant differences among the four groups with respect to total extruded debris. The amount of extruded debris was positively correlated with the amount of irrigant extruded. Factors such as canal length, curvature, and foramen size did not affect the amount of debris extruded.

Analysis of Variance↗
PubMed1998

Strengthening immature teeth during and after apexification.

The purpose of this study was to evaluate the strengthening effect of an internal resin bonding technique. One hundred central incisors were endodontically treated and divided equally into five groups. Group 1, without any cervical preparation and with access repaired with bonded resin, served as the positive control. Teeth in groups 2 to 5 were cervically prepared to simulate the thin dentinal wall of immature teeth, and obturation material was removed to 3 mm below the cementoenamel junction (CEJ). In group 2, the negative control, the access was restored with bonded composite to the level of the CEJ. In group 3, access was restored with composite resin 3 mm apical to the CEJ using a clear post system. Group 4 was treated similarly to group 3, but an opaque post replaced the clear post. Group 5 was treated like group 3, after which a metal post was cemented into the channel left after removal of the clear post. All teeth were subjected to compression testing and the force required to fracture the teeth cervically was recorded for each group and the Kruskal-Wallis analysis performed to detect intergroup differences. All of the bonded resin techniques significantly strengthened the teeth against fracture, compared with the negative control group (p < 0.05). None of the experimental groups (3-5) were significantly different from the positive control group.

Composite Resins↗
PubMed1998

A clinical study using the collagen gel Zyplast in endodontic treatment.

The use of a collagen gel as a hard tissue induction material in fractured and undeveloped teeth is reviewed. Three of four cases demonstrate a modest amount of hard tissue formation within the pulp space previously occupied by the collagen gel. Limitations in positive results, compared with a previous animal study and one clinical case report, are probably due to the pre-existence of infection in the present study.

Adolescent↗
PubMed1998

Black-pigmented bacteria in coronal and apical segments of infected root canals.

Black-pigmented bacteria (BPB) have been associated with infections of endodontic origin. The purpose of this study was to culture and identify BPB from the apical and coronal segments of infected root canals to understand better their ecological relationships. Teeth with a periapical radiolucency were extracted and immediately placed in reduced transport fluid for transport to an anaerobic chamber. Of 18 sampled roots, 12 were positive for the growth of BPB. Eight of the 12 roots with BPB had a carious exposure of the pulp chamber. Seven roots had Prevotella nigrescens in both the apical and the coronal segments. Six of these seven teeth had carious exposures of the pulp chamber. Of the 12 roots infected with BPB, six roots had two different species of BPB, with P. nigrescens always being one of the species. P. nigrescens was the most often isolated BPB from both the coronal and apical segments of infected root canals.

Colony Count, Microbial↗
PubMed1998

A photoelastimetric analysis of stress induced by root-end resection.

The aim of this study was to place into perspective some factors that played an important role in the healing of periapical lesions after surgical endodontic procedures. Root-ends were sectioned at different angulations on models and analyzed by photoelastimetry. Results showed that a section of the root-end through a plane perpendicular to the long axis of the tooth offers a better distribution of the stresses exerted on the apical region that the use of an inclined plane. The biological implications of these results have led the authors to propose a plan of resection that is perpendicular to the long axis of the tooth instead of the inclined plane commonly used.

Birefringence↗
PubMed1999

Clinical applications of mineral trioxide aggregate.

An experimental material, mineral trioxide aggregate (MTA), has recently been investigated as a potential alternative restorative material to the presently used materials in endodontics. Several in vitro and in vivo studies have shown that MTA prevents microleakage, is biocompatible, and promotes regeneration of the original tissues when it is placed in contact with the dental pulp or periradicular tissues. This article describes the clinical procedures for application of MTA in capping of pulps with reversible pulpitis, apexification, repair of root perforations nonsurgically and surgically, as well as its use as a root-end filling material.

Aluminum Compounds↗
PubMed1999

Residual thickness of root in first maxillary premolars with post space preparation.

It has been suggested that, to ensure tooth strength, a minimum of 1 mm of root wall thickness should be left after post preparations. The purpose of this study was to determine the instrument diameter that will not affect this measurement in maxillary first premolars. Post preparations were made in 106 teeth with one and two root canals at a working depth equal to the anatomical crown length, with 0.70, 0.90, 1.10, 1.30, 1.50, and 1.70 mm diameter instruments. Sections were cut perpendicular to the long axis of the tooth at the cervical and apical ends of each preparation, and the minimum width of residual root was measured on each wall, at both sites. A binocular microscope with a micrometer eyepiece was used. At the cervical level of the preparation, no group showed a wall thickness < 1 mm. Data for the apical sections was statistically analyzed, and the corresponding confidence limits were calculated with 95% confidence on the mean. The results show that the minimum residual thickness was only preserved when 0.70 mm instruments were used in single-canal roots and when 1.10 mm or smaller instruments were used for two-canal roots. This seemingly anomalous result occurs because fluting on both the mesial and distal sides of the root impinge on single canals, whereas dual canals are buccally or lingually displaced to an area of thicker root diameter.

Bicuspid↗
PubMed1999

A scanning electron microscopic study of in vivo ultrasonic root-end preparations.

The purpose of this in vivo study was to evaluate root-ends for cracks after root resection and again after ultrasonic root-end preparation in patients undergoing endodontic surgery. Endodontic surgery was performed on 25 roots from 20 patients. In vivo vinyl polysiloxane impressions were made after root resection and again after ultrasonic root-end preparations. Epoxy resin casts were made from the impressions and scanning electron micrographic examination of the root-end replicas was performed. There was no evidence of cracks after root resection. One incomplete canal crack was evident after ultrasonic root-end preparation.

Apicoectomy↗
PubMed2004

Density of dentinal tubules affects the tensile strength of root dentin.

OBJECTIVES: The aim of this study is to count the dentinal tubules in the coronal and middle-apical third of root dentin of teeth extracted due to the progression of periodontal disease, and to compare the Ultimate Tensile Strength (UTS) of the same areas. The research hypothesis was that root dentin areas with different densities of dentinal tubules would also show different UTS values. METHODS: From 10 caries free maxillary central, lateral incisors and canines, extracted for periodontal reasons from three patients, cylindrical specimens approximately 10 mm long were prepared parallel to the long axis of the root and then divided into two parts using a low speed diamond saw one from the coronal third of the root, (Group 1) and one from the middle-apical third of the root (Group 2). The density of the dentinal tubules of the specimens of the two groups was measured by means of a scanning electron microscope and the UTS of the specimens was measured by a microtensile test. One way ANOVA was used to assess the effect of specimen location (coronal specimens vs. middle-apical specimens) on UTS. The differences in the density of dentinal tubules between coronal and middle-apical specimens were also subjected to statistical analysis using one-way ANOVA. RESULTS: UTS values of middle-apical specimens were found to be significantly (p < 0.05) higher than those of coronal specimens. The results of the one-way analysis of variance showed that the number of dentinal tubules of the samples from the coronal part of the root groups was significantly higher than that of samples from the middle-apical part (p < 0.05). SIGNIFICANCE: These results suggest that high values of tensile strength of the dentin are associated with low densities of dentinal tubules and that apical areas of root dentin are more resistant to tension than coronal ones.

Analysis of Variance↗
PubMed2004

Use of dental panoramic tomographs to predict the relation between mandibular third molar teeth and the inferior alveolar nerve. Radiological and surgical findings, and clinical outcome.

OBJECTIVES: To compare preoperative radiological observations from dental panoramic tomographs (DPT), with surgical findings at removal of third molars with respect to the inferior alveolar nerve. STUDY DESIGN: One surgeon viewed the radiographs of 219 patients and recorded the radiological observations of the mandibular third molar tooth and the inferior alveolar nerve. The same surgeon removed the teeth and made detailed records of morphology of the root and its relation to the inferior alveolar nerve. Patients were reviewed postoperatively. RESULTS: A total of 300 teeth were removed and the neurovascular bundle was directly observed the root was grooved, or roots apices were deflected by the bundle in 35 (12%) cases. Postoperatively no patient had altered labial sensation. CONCLUSION: There was an intimate relation between the mandibular third molar tooth and the inferior alveolar nerve in 12 (51%) cases when darkening of the root was observed, and in only 11 (11%) cases when interruption of the radiopaque outline of the inferior alveolar neurovascular bundle was observed.

Follow-Up Studies↗
PubMed2003

Bacterial penetration through canals of endodontically treated teeth in the presence or absence of the smear layer.

OBJECTIVES: The goal of this study is to determine if the smear layer affects the passage of bacteria through or around obturating material as evidenced by penetration of bacteria through and out the canal. Specifically, this study focused on determining the effect of the smear layer on the magnitude of bacterial penetration through the apical foramen. METHODS: Thirty extracted, maxillary central or lateral incisors were collected. Teeth were randomly assigned (10 teeth per group) to three groups: (1) smear layer removed, (2) smear layer present, and (3) negative control. Canal preparation and obturation using lateral condensation, gutta percha, and AH 26 sealer was performed on all of the teeth. Removal of the smear layer was accomplished by rinsing with 17% EDTA. The model systems consisted of an upper chamber attached to the cemento-enamel junction and a lower chamber at the apices of the teeth. Standardized bacterial suspensions containing Fusobacterium nucleatum, Campylobacter rectus, and Peptostreptococcus micros were inoculated into the upper chambers. Models were incubated anaerobically at 37 degrees C. At various times over a 60-day period, samples were taken from the lower chamber and spiral-plated on selective-differential media to determine numbers and types of bacteria. RESULTS: Leakage results were as follows: (1) smear layer present-6/10 leaked; (2) smear layer removed-0/10 leaked; (3) negative control-0/10 leaked. Profiles of bacterial leakage were similar among the groups. F. nucleatum was the predominant microorganism. CONCLUSIONS: This study indicated that removal of the smear layer reduced the leakage of bacteria through the root canal system.

Bismuth↗
PubMed1983

Intraligamentary--intraosseous anesthesia. A radiographic demonstration.

Intraligamentary dental anesthesia has become a widely accepted technique. The periodontal ligament seems to provide easy access to the tooth apex. In the present study, radiopaque material was injected into baboon monkeys. Serial radiographs during incremental injections showed clouding of the crestal bone. The material was seen gradually advancing through the alveolar bone crest, apically. The spread was noticed through the marrow spaces, unexpectedly avoiding the PDL route.

Alveolar Process↗
PubMed1999

Radiographic localization of unerupted maxillary anterior teeth using the vertical tube shift technique: the history and application of the method with some case reports.

The preferred means of radiographic localization is the parallax method introduced by Clark in 1910. He used 2 periapical radiographs and shifted the tube in the horizontal plane. In 1952, Richards appreciated that a vertical tube shift could also be carried out. No major changes then occurred in the technique until Keur, in Australia, in 1986 replaced the periapical radiographs with occlusal radiographs. This modification enables a greater tube movement and therefore a greater shift of the image of the impacted tooth; it also ensures that the whole of the tooth is captured on the radiograph. For the vertical tube shift, Keur introduced the use of a rotational panoramic radiograph with an occlusal radiograph. In 1987, Southall and Gravely discussed this vertical tube shift combination in the English dental literature, and it is now the preferred combination of radiographs for localizing impacted maxillary anterior teeth. Jacobs introduced this method to the American literature in 1999, but it has yet to gain acceptance in the continental European literature. Jacobs recommended, when using this combination, to routinely increase the vertical angulation for the occlusal radiograph by 10 degrees to achieve a greater image shift. Four case reports are presented in this article. Three have photographs taken at surgical exposure to illustrate how the position of the impacted tooth can be accurately predicted by appropriate interpretation of the radiographs.

Adolescent↗
PubMed2004

Effects of nitric oxide in orthodontic tooth movement in rats.

The purpose of this study was to evaluate the role of nitric oxide (NO) in orthodontic tooth movement in rats. Nomega-nitro-L-arginine methyl ester (L-NAME) was used as NO synthase (NOS) inhibitor, and nitro-L-arginine (NLA) was used as NOS precursor. Fifty-four Sprague-Dawley rats were divided into 3 equal groups, and each group was divided into 3 subgroups. In the first 8 subgroups, 20 g of force was applied to the maxillary incisors with a spring. NLA was administered in the first 3 subgroups at 10(-4), 10(-5) and 10(-6) mol/L (20 microL/12 hours), respectively. L-NAME was administered in the next 3 subgroups with the same order, amount, and prescription. The last 3 subgroups were evaluated as control groups; in the seventh subgroup, 0.9% NaCl (saline solution) was injected (20 microL/12 hours). Only the force was administered in the eighth subgroup, and no chemical solution or orthodontic force was used in the last subgroup. The rats were killed on the fifth day of the experiment. Their premaxillae were dissected, and tissue sections were obtained from the coronal, middle, and apical thirds of the incisor roots. Multinuclear osteoclasts, Howship's lacunae, capillary vascularization, and orthodontic tooth movement were significantly increased in the NLA groups compared with the L-NAME and control groups.

Animals↗