Saad Al-Nazhan

Morphological cell changes due to chemical toxicity of a dental material: An electron microscopic study on human periodontal ligament fibroblasts and L929 cells

New endodontic materials with polymer bases may be more difficult to evaluate in cell cultures in vitro than conventional zinc oxide-eugenol cements. In order to study the morphological changes taking place in cells exposed to such materials, L929 cells and human periodontal fibroblasts were observed using scanning electron microscopic and transmission electron microscopic techniques. The morphological changes of the cells were correlated to the quantitative results observed simultaneously in cytotoxicity studies using the radiochromium release method. Results showed there was a relationship between the chromium release and the degree of individual cell damage. The periodontal ligament fibroblasts were more resistant to this kind of chemical injury than the L929 cells. Consequently, it may be proper to use periodontally derived cells for the study of cytotoxic mechanisms of polymer endodontic filling materials.

Evaluation of Antifungal Activity of Mineral Trioxide Aggregate

The purpose of this investigation was to study, in vitro, the antifungal effect of mineral trioxide aggregate (MTA) using a tube-dilution test. MTA was tested freshly mixed and after 24 h set on Candida albicans. The tested MTA was incubated with C. albicans for 1 h, 24 h, and 3 days. Results showed that the freshly mixed MTA was effective in killing the tested fungi after 1 day of contact, whereas the 24-h set MTA was effective after 3 days of incubation. It was concluded that MTA (freshly mixed and 24-h set) was effective against C. albicans.

Evaluation of the effect of delayed management of traumatized permanent teeth

This investigation studied the complication that could arise from delayed management of traumatized permanent teeth. Patients reported to the primary care clinic at the College of Dentistry, King Saud University, seeking treatment of traumatized anterior teeth were evaluated. Esthetic consideration (64 patients) and pain, swelling, or discomforts (50 patients) were the main reasons the patients came to the clinic. Clinical and radiographic examinations, as well as history of the trauma, were recorded. It was found that most of the patients had a treatment delay exceeding 1 month. Initial pulp exposure resulted in 100% pulp necrosis. When a fracture involved both enamel and dentin, the frequency of pulp necrosis was 53%. External root resorption and pulp calcification were seen in few teeth. It was concluded that the figures for pulp necrosis could be misleading, because there might have been a bias when only patients with problems sought treatment. In addition, a trauma awareness educational program should be developed to encourage parents and the public to seek immediate dental treatment. Furthermore, a proper diagnostic test for pulp and periodontal complication should be done in patients with initially nontreated dental injuries.

External root resorption after bleaching: A case report

An external root resorption occurred after bleaching and was diagnosed radiographically in a 26-year-old female dental assistant. The resorption was noticed 6 months after bleaching. The involved tooth had no history of trauma. An attempt to stop the resorption by using calcium hydroxide failed. The perforation was corrected surgically with amalgam.

Radiation Dose Reduction During Endodontic Therapy: A New Technique Combining an Apex Locator (Root ZX) and a Digital Imaging System (RadioVisioGraphy)

This study was undertaken on 14 teeth in order to evaluate a new technique for radiation dose reduction during endodontic therapy. After examination of the preoperative film, usually available in the patient file, an apex locator (Root ZX) was used to measure the working length. Complete chemomechanical debridement was then performed, and the master cone was evaluated by a digital imaging system (RadioVisioGraphy (RVG)). Obturation was performed when measurements of the electronic device and RVG were comparable. A postoperative image was made by the RVG system to evaluate the final obturation. A clinical and radiographic follow-up examination (follow-up period: 6 to 8 months) revealed satisfactory apical healing. These results indicated that a successful obturation technique can be performed by a single radiation exposure, using the RVG unit for master cone evaluation. This technique may be useful in medically compromised patients who need not to be exposed to excessive or repeated radiation during endodontic therapy.

Two root canals in a maxillary central incisor with enamel hypoplasia

Presented is a case of enamel hypoplasia of a maxillary central incisor which was referred for endodontic therapy. Radiographical examination revealed a tooth having one root and two canals. Endodontic therapy was performed under aseptic conditions.

Effectiveness of a 2% chlorhexidine solution mixed with calcium hydroxide against Candida albicans

The purpose of this investigation was to examine the in vitro susceptibility of Candida albicans to a mixture of chlorhexidine and calcium hydroxide using a tube dilution test. A suspension containing C. albicans was exposed to 2% chlorhexidine solution, calcium hydroxide paste and 2% chlorhexidine mixed with calcium hydroxide in plastic tissue culture wells. The tested agents were incubated with C. albicans for 1, 24, or 72 h. All agents were effective anti-fungals at all experimental time periods tested, with the exception of exposure to calcium hydroxide for 1 h. A mixture of 2% chlorhexidine and calcium hydroxide therefore is a very effective anti-fungal agent against C. albicans.

In vitro study of the toxicity of a composite resin, silver amalgam, and Cavit.

Cytotoxicity of a composite resin (Restodent), suggested for use as a retrograde endodontic filling material, was evaluated in vitro and compared with silver amalgam and Cavit. Materials were evaluated freshly prepared and after 1 and 7 days setting at 37°C and 100% humidity. Results showed that Restodent was more toxic than silver amalgam. Cavit had no toxic effect. Although Restodent was reported to have better sealing properties than silver amalgam in vitro, the latter, due to its lower toxicity, is still the material of choice for retrograde root canal filling.

Microorganism penetration in dentinal tubules of instrumented and retreated root canal walls. In vitro SEM study

Objectives This in vitro study aimed to investigate the ability of Candida albicans (C. albicans) and Enterococcus faecalis (E. faecalis) to penetrate dentinal tubules of instrumented and retreated root canal surface of split human teeth. Materials and Methods Sixty intact extracted human single-rooted teeth were divided into 4 groups, negative control, positive control without canal instrumentation, instrumented, and retreated. Root canals in the instrumented group were enlarged with endodontic instruments, while root canals in the retreated group were enlarged, filled, and then removed the canal filling materials. The teeth were split longitudinally after canal preparation in 3 groups except the negative control group. The teeth were inoculated with both microorganisms separately and in combination. Teeth specimens were examined by scanning electron microscopy (SEM), and the depth of penetration into the dentinal tubules was assessed using the SMILE view software (JEOL Ltd). Results Penetration of C. albicans and E. faecalis into the dentinal tubules was observed in all 3 groups, although penetration was partially restricted by dentin debris of tubules in the instrumented group and remnants of canal filling materials in the retreated group. In all 3 groups, E. faecalis penetrated deeper into the dentinal tubules by way of cell division than C. albicans which built colonies and penetrated by means of hyphae. Conclusions Microorganisms can easily penetrate dentinal tubules of root canals with different appearance based on the microorganism size and status of dentinal tubules.

Pulp revascularization of immature maxillary first premolar.

An immature maxillary first premolar in an 8-year-old female was treated using a regenerative approach. The root canal was gently irrigated with 5.25% sodium hypochlorite without instrumentation under aseptic conditions and then medicated with calcium hydroxide (Ca[OH]2) for 3 weeks. The Ca(OH)2 was removed, and bleeding was initiated mechanically using a hand file to form an intracanal blood clot. Mineral trioxide aggregate was placed over the blood clot, and the access cavity was sealed with a double filling. Increases in root length and width were radiographically evident, at the 6-month follow-up exam. The case was followed for 3 years. The development of 3 roots with complete apical closure was confirmed using cone beam computed tomography.