In vivo tetracycline labeling of experimentally induced reparative dentin in human teeth.

Tetracycline hydrocholoride was administered to label reparative dentin in teeth indicated for extraction. Deep cavities or pulp capping performed on the teeth one of four months before extraction served as a stimulus for new dentin formation. Examination of undemineralized sections under ultraviolet light revealed fluorescent bands in the reparative dentin of most teeth. The technique can be safely used in studies of the effects of clinical procedures on the dentin and pulp of human teeth.

Vital root amputation. A clinical and histological study.

An investigation was designed to study the clinical and histological effects of delaying endodontic therapy for a period of 2 weeks without dressing of the exposed pulp, after vital intentional root amputation had been carried out on periodontally involved teeth. From the results obtained it was possible to conclude that: 1. Endodontics, prior to surgical root amputation, remains the treatment of choice. 2. When preoperative endodontics is not possible, the approach used in this study will provide good results without severe, adverse clinical or histological effects. 3. The altered periodontal condition and tooth form do not interfere with the performance of definitive endodontics 2 weeks after surgery. 4. Definitive preparation of the cut tooth surface at the time of root amputation facilitates maintenance of oral hygiene after removal of the periodontal dressings. 5. The high percentage of involvement of the distobuccal root of the first maxillary molar in periodontal situations requiring correction by root amputation, may be due to the anatomy of this root.

Sealing ability of a new hydroxyapatite-containing endodontic sealer using lateral condensation and thermatic compaction of gutta-percha, in vitro.

A new sealer that contains hydroxyapatite has been developed; the additive is assumed to influence apical healing, but it may also affect the sealing ability of the cement because of its composite structure. The purpose of this study was to evaluate the sealing ability of Bioseal and to compare it with that of another zinc oxide-eugenol sealer (Pulp Canal Sealer), using a lateral condensation technique and thermatic compaction of gutta-percha. The study was conducted on 42 straight roots, prepared to apical size 35 to 40 and randomly separated into four groups. After obturation, the roots were suspended for 1 wk in methylene blue and sectioned transversely for measuring penetration of the dye. In the roots filled with Bioseal, the mean penetration was 1.1 mm for lateral condensation and 1.5 mm for thermatic compaction. In the Pulp Canal Sealer groups, the values were 1.4 mm for both. The difference was not significant at the 5% level (Mann-Whitney U test), indicating that the additive did not adversely affect the sealing properties.

Tubular permeability to calcium hydroxide and to bleaching agents.

Recent reports of clinical cases suggest that cervical root resorption may follow bleaching of endodontically treated teeth. Inflammatory root resorption may be arrested by placement of calcium hydroxide into the root canal. The dentinal tubules are assumed to be a possible route of action for both agents. pH Values of the medium surrounding the tooth after placement of bleaching agents and calcium hydroxide within the root canals were determined in this study. Thirty extracted single-rooted human teeth were divided into three equal groups. The pulp cavity of the experimental teeth was filled with either bleaching agents or calcium hydroxide. In the control group it was left empty. Dipping in paraffin sealed the access cavity and the apical foramina and isolated the teeth except at the cervical root surface. The teeth were placed in vials containing distilled water and the pH of the medium was measured after 1 h, 3 days, and 7 days following renewal of the medium. The level of the pH in the first group increased, indicating that the bleaching agents leaked from the root canal to the medium surrounding the teeth. The pH in other two groups did not change noticeably. The results suggest that bleaching agents may leak from the root canal toward the periodontal tissues but calcium hydroxide does not alkalinize the medium surrounding the teeth. Leakage of the bleaching agents through dentin may, therefore, be considered as a possible etiological factor that initiates an inflammatory process around the teeth that may be followed by cervical root resorption.

Periodontal ligament injection: spread of the solution in the dog.

Investigations of the spread of anesthetic solutions administered with the periodontal ligament injection have reported conflicting findings. The purpose of this investigation was to study the distribution of the injected fluid by macroscopic and microscopic techniques. One third of the liquid of the carpules (2% lidocaine with 1:100,000 epinephrine) was replaced with India ink as a marker. Injections were made with a pressure syringe, (Ligmaject) at 90 sites in 12 dogs. Twenty-five control sites were injected with a marked solution without a vasoconstrictor (3% mepivacaine). Seven dogs were killed within 24 h; the others after 5 days. Spread of the ink was studied in undemineralized slices, in three-dimensional cleared specimens, and in histological sections. The solution usually reached the alveolar crest, seeped under the periosteum, and entered into bone marrow spaces alongside vascular channels. The ink spread along the path of least resistance, influenced by the intricacies of anatomical structures and fascial planes, rather than penetrating into the periodontal ligament or in the root canal. In the controls without a vasoconstrictor the spread was more diffuse. Five days postoperatively, carbon particles were present only within macrophages.

Correlation between remaining length of root canal fillings after immediate post space preparation and coronal leakage.

The seal provided by root canal fillings after post space preparation was studied using a pressure-driven radioactive tracer assay. The coronal part of root canal fillings was immediately removed, using a hot plugger, to a remaining length of either 3, 5, 7, or 9 mm. Intact root canal fillings of 14 mm served as control. Application of air pressure of 130 mm Hg to the tracer solution drove it through the fillings and into phosphate-buffered saline surrounding the apex. Leakage gradually increased for 28 days, and differences in the leakage through 3 to 9 mm fillings were demonstrated. In a passive system by which an additional group of teeth were tested none of these differences could be detected. It was concluded that: (a) root canal fillings of 3, 5, and 7 mm have an inferior seal, compared with that of an intact filling; (b) the sealing is proportional to the length of the remaining filling; and (c) a passive system is unable to detect these differences, even when conducted for as long as 28 days.

The effect of immediate vs. delayed post space preparation on the apical seal of a root canal filling: a study in an increased-sensitivity pressure-driven system.

A 5 mm remaining length of root canal filling, after post space preparation, is commonly assumed to maintain sealing ability similar to that of the intact filling. Post spaces were prepared either immediately using hot pluggers, or later, using drills. The sealing ability of the fillings, 5 mm remaining length, were compared with each other and with an intact root canal filling control, using radioactive tracer in a pressure-driven system. When no pressure was applied, no differences could be detected between either of the groups and the control. When a pressure of 120 mm Hg was applied to the same teeth, the control group clearly maintained a better seal than each of the experimental groups, which did not significantly differ from each other. These results suggest that (a) the pressure-driven system was more sensitive than the passive leakage assay that failed to detect differences even at 14 days; (b) a remaining root canal filling of 5 mm was inferior to the intact root canal filling; and (c) the immediate post space preparation with hot pluggers did not differ from a delayed preparation with drills.

Intracanal pH changes of calcium hydroxide pastes exposed to carbon dioxide in vitro.

It has been suggested that the main benefit of using calcium hydroxide as an intracanal medicament lies in its bactericidal effect, provided that the pH of the paste is above 12.5. The purpose of this study was to measure changes in the pH of several calcium hydroxide pastes sealed in root canals for 30 days. Sixty-two extracted, single-rooted human teeth were endodontically prepared using K-files up to size 60. The teeth were separated at random into six equal groups to be filled with either Calxyl, Hydrocalcium, or a paste made by mixing calcium hydroxide powder with either distilled water, camphorated p-monochlorophenol, local anesthetic solution, or Solvidont. Cavidentin was used to seal the coronal orifice of the teeth that were placed individually in vials containing 10 mL distilled water. Five vials of each group were exposed to air at room temperature, whereas the other five vials were exposed to carbon dioxide in a closed container. The pH of the paste in the root canal was measured after 30 days. There was no significant (p > 0.01) change in the pH (mean 13.11) of the pastes placed in teeth before and after exposure to air, whereas the pH of the pastes in teeth exposed to carbon dioxide was significantly (p < 0.01) reduced (mean 12.54). There was no significant difference in pH between the six preparations. After 30 days of exposure to carbon dioxide, they still maintained a purportedly bactericidal pH within the root canal.

Life and AH26 as sealers in thermatically compacted gutta-percha root canal fillings: leakage to a dye.

Calcium hydroxide-containing root canal sealers may encourage apical obturation by cementum. Hard-setting bases with calcium hydroxide induce calcification, but set too quickly to permit lateral condensation of gutta-percha. Since thermatic compaction requires less time than lateral condensation, the possibility of using this method with Life as a sealer was investigated. Seventy roots were prepared and filled with gutta-percha using the Engine Plugger for thermatic compaction. In one group of 20 Life was used as a sealer. AH26 was used in another group of 20. The remainder served as controls. Leakage was tested by linear penetration of Procion B Blue dye measured after clearing the teeth. In the Life group the mean dye penetration was 0.575 mm versus 1.025 mm in AH26, but the difference was not statistically significant. The results indicated that Life could be used in thermatic compaction of gutta-percha and that it provided a seal comparable to that obtained with AH26.

Densitometric measurement of radiopacity of Gutta-percha cones and root dentin.

National and international standards require that gutta-percha cones be sufficiently radiopaque to be distinguished from natural structures such as dentin and to permit evaluation of the density of the root canal filling. Discs, 1-mm thick, made from 15 commercial and experimental brands of gutta-percha cones, were tested for their compliance with the requirements. The radiopacity of 1-mm thick root dentin slabs was similarly measured with a photo-densitometer. All radiographs were made on D-speed occlusal film and replicated on E-speed film. The mean radiopacity of the gutta-percha discs on D-speed film was 7.26 mm of aluminum equivalent and 7.53 mm on E-speed film, greatly exceeding the minimal requirement of 3 mm. The difference in the values obtained with the two film types was not significant, suggesting that E-speed films may be used for the test. Dentin slabs were uniform in their radiopacity, equivalent to 1 mm of aluminum, confirming previous findings. In view of complaints of insufficient clinical performance, the present minimal requirement for radiopacity of gutta-percha cones seems too low.

Russell bodies in the pulp of a primary tooth.

Russell bodies can be found in the majority of the inflamed tissues throughout the body. They have been shown to consist of accumulations of normal globulins that may burst out of the distended plasma cells that secrete them. Russell bodies have also been described in oral tissues and are believed to occur in 80% of the chronic periapical lesions. Yet their occurrence in the pulp has not been subjected to scrutiny. Concentrations of large intracellular (in-plasma cells) and extracellular Russell bodies have been found in the inflammatory tissue occupying the pulp cavity of carious primary teeth. Their significance is so far unknown.

Working well: a healthy employee means a wealthy organization.

The financial manager as "manager" of the organization's resources, manages both financial and human resources. In this interview, Mark J. Tager, MD, discusses how a manager can affect an employee's wellness on the job, or promote "working well". Wellness means both physical health and mental stamina. Employees at a high level of wellness are more creative, positive, and productive. According to Tager, there are five characteristics that can create wellness and help the employee to perform better on the job. These five characteristics--participation, environment, recognition, knowledge, and style or PERKS--are a set of practical management guide-lines that can help managers cultivate and protect their human resources.