Cellular toxicity of mineral trioxide aggregate mixed with an alternative delivery vehicle.

OBJECTIVE: Mineral trioxide aggregate (MTA) mixed with water has a short working time, delayed setting, and poor consistency. A preliminary study suggested that substituting KY Jelly as a mixing vehicle improves the working properties of MTA. The present study compared the biocompatibility of white MTA mixed with water or with KY Jelly to that of Fuji II cement and of silver amalgam. STUDY DESIGN: Periodontal ligament (PDL) cells were cultured using standard laboratory procedures. Cells were plated in wells at a density of 10,000 cells/well. The test materials were mixed and eluate placed in contact with the PDL cells. Cell viability was determined by measuring mitochondrial enzyme activity using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenytl)-2H-tetrazolium inner salt assay. Cytotoxicity was also measured in terms of cell lysis using the lactate dehydrogenase assay. The assays were completed in triplicate after time intervals of 24, 48, and 72 h. Mean cell counts were calculated and converted to a percentage of control results. A 2-way analysis of variance and Tukey honestly significant difference post-hoc test were performed to determine statistical significance. RESULTS: Eluate extractions from all materials caused significantly less cell viability and more cell death than control eluate (medium only) at all eluate time points tested. However, at 72 h the MTA/water, MTA/KY, and amalgam eluate extractions led to significantly better cell viability than the Fuji II eluates. However, there was significantly greater cell lysis for all eluates from the tested materials at 72 h than at 24 h. CONCLUSIONS: Within the limitations of this in vitro study, we conclude that MTA/KY, MTA/water, and amalgam have similar biocompatibility regarding effects of their eluates on human PDL cells, and eluates from all 3 materials demonstrate better biocompatibility than eluates derived from a resin-modified glass ionomer cement.

Effect of spreader and accessory cone size on density of obturation using conventional or mechanical lateral condensation.

A simulated curved root canal in a resin block was enlarged to size 40 and used to compare the depth of accessory cone penetration and weight of obturation occurring with the use of different obturation techniques and spreader-accessory cone combinations. Twelve groups, each consisting of 10 obturations, were created. A conventional lateral condensation technique was used in six groups and a mechanical lateral condensation (MLC) technique was used in six matched groups. The six spreader-accessory cone combinations were either Fine-Medium or Fine nickel-titanium finger spreaders with either Fine, Medium-Fine, or size 25 accessory cones. Seven accessory cones were placed in every obturation. The depth of each accessory cone penetration into the canal was measured. After each obturation the gutta-percha was removed, sectioned, and the resulting mass was weighed. The means for each variable were determined and compared. MLC fills were significantly heavier and had greater depth of penetration on average than conventional lateral condensation. The best combination for heavy fills was MLC, Fine-Medium spreaders, and Fine accessory cones. The greatest mean accessory cone depth occurred with MLC, Fine-Medium spreaders, and size 25 accessory cones.

Comparison of fracture rate, deformation rate, and efficiency between rotary endodontic instruments driven at 150 rpm and 350 rpm.

Two groups of 30 mature molars each (S and F) were instrumented with Profile .04 taper Series 29 rotary instruments. Group S molars were instrumented at 150 rpm and group F at 350 rpm. The number of fractures, deformed files, and instrumentation time were recorded for each tooth. No instrument fractures occurred in either group. In group S the mean deformation rate and instrumentation time were 1.1 deformed files and 8.0 min per molar. In group F they were 0.57 deformed files and 4.6 min per molar. Both differences were significant (p < 0.05). The results indicate that Profile .04 taper Series 29 rotary instruments should be used at 350 rpm to nearly double efficiency and halve the deformation rate, compared with 150 rpm. Because no instrument fractures occurred while instrumenting 60 mature molars, both speeds should be considered safe.

A description of an alternative method of lateral condensation and a comparison of the ability to obturate canals using mechanical or traditional lateral condensation.

A modification of the lateral condensation of gutta-percha technique is described. After master cone adaptation is completed a nickel-titanium finger spreader placed in a reciprocating-action handpiece is used to laterally displace cold gutta-percha, creating space for accessory cones. The technique produces a compacted mass of gutta-percha in the canal, which can usually be removed in toto if corrections are required. This technique was compared with lateral condensation by obturating curved or straight canals in acrylic blocks, then removing, sectioning, and weighing the gutta-percha mass. Two different operators were also compared. Results were analyzed using a factorial ANOVA test. The experimental obturations were significantly heavier on average than were lateral condensation fills (p < 0.001). One operator's obturations were consistently heavier than the others (p < 0.001). There was no significant difference between the weight of fills in straight and curved canals.

Pulp stones throughout the dentition of monozygotic twins: a case report.

Pulpal calcifications are relatively common. However, their occurrence in the entire dentition is relatively infrequent. The presence of such calcification arouses suspicion of systemic or hereditary origin. This case report describes twin sisters with pulpal calcifications in their entire dentitions. No systemic cause was detected. The pattern of calcification was partially consistent with the hereditary condition of dentinal dysplasia.

Treatment options for the radicular lingual groove: a review and discussion.

The radicular lingual groove (RLG) is a developmental anomaly in which an infolding of the inner enamel epithelium and Hertwig's epithelial root sheath create a groove that passes from the cingulum of maxillary incisors apically onto the root. Radicular lingual grooves can create periodontal and pulpal pathology, but they may be difficult to identify as an etiological factor. This article identifies the diagnostic and treatment modalities for the various forms of RLGs and describes the prognosis that can be anticipated with each treatment modality.

Dens invaginatus--a pathway to pulpal pathology: a literature review.

Dens invaginatus is the most common dental anomaly in a group of dental anomalies, related by their embryologic development and by the fact that their defects provide a potential pathway for bacteria to cause pulpal pathology. It occurs when the inner enamel epithelium invaginates into the dental papilla prior to calcification. It exists in erupted teeth as an enamel-lined tract, which either ends in a blind sac inside the crown or root or exits into the periodontal ligament. The lining may be incomplete in areas and may not protect the pulp. Methods of providing preventive treatment for teeth with dens invaginatus are described. When pulpal pathosis occurs, the dens may displace the pulp and complicate access cavity preparation and subsequent endodontic treatment, adversely affecting the prognosis. The learning objective of this article is to present treatment planning considerations and suggestions.

Preeruptive idiopathic coronal resorption: a case report.

A bitewing radiograph obtained from a general dentist revealed an intracoronal radiolucency within an unerupted immature permanent second molar. This rare entity was successfully treated by surgical exposure and vital pulp therapy. Apexogenesis was confirmed radiographically and a permanent restoration placed at the time of eruption. Possible etiologies for this condition are discussed and recommendations for treatment are proposed.

Factors that affect the rate of retakes for endodontic treatment radiographs.

The purpose of this study was to determine the most accurate method of taking radiographs during endodontic treatment to minimize the number of retakes. To accomplish this, the rate of retakes in an endodontic clinic at a dental school was measured. Then the effect that two factors, anatomic location and type of film holder, had on this rate were calculated and analyzed. Criteria for acceptability were that radiographs have adequate coverage and minimal distortion. Two endodontists evaluated endodontic treatment radiographs taken by undergraduate dental students to determine if these criteria were met. Of 402 films evaluated 77% were considered to be acceptable. A significantly higher rate of acceptability occurred with films taken in the mandible compared with those taken in the maxilla. The EndoRay (Rinn Corp., Elgin, Ill.) and hemostat were the only types of film holders compared. Films taken with the EndoRay in the maxilla had a significantly higher acceptability rate than those taken in the maxilla with a hemostat. No difference in acceptability existed between the two film holders when radiographs were taken in the mandible.