Evaluating IL-2 levels in human pulp tissue

In murine and human CD4+ T cell populations, there are three subpopulations of T helper cell types. Hahn et al. demonstrated the ratio of CD4/ CD8 + cells significantly increases in inflamed dental pulps compared with normal pulps. Elevated levels of interleukin (IL)-2 have been detected in inflamed dental pulps and the level of IL-2 could be used as a marker for inflammation. In this study, levels of IL-2 were evaluated by using a human IL-2 cytokine assay kit on 80 samples of freshly extracted human pulp tissue. Applying standard diagnostic procedures, the tissue samples were clinically categorized into one of three experimental groups. The results demonstrated that there were no significant differences between the concentrations of IL-2 in any of the experimental groups. Our findings are different from results reported previously. Further investigation is warranted to determine if a correlation exists between the concentration of IL-2 or other interleukins and the degree of inflammation present in the dental pulp.

The effect of root canal preparation on microleakage within endodontically treated teeth: an in vitro study

AIM

The purpose of this study was to evaluate the effects of smear layer and canal instrumentation on leakage in root-filled teeth.

METHODOLOGY

Six groups (n = 12) of freshly extracted human canines and premolars with closed apices and single roots were used. Groups A, B, C, and D were instrumented with engine-driven rotary nickel-titanium MCXIM files and Groups E and F were instrumented with conventional stainless steel hand files. Groups A, C, and E were flushed with 3.0 mL of 17.0% REDTA to remove the smear layer prior to obturation. All teeth were flushed with 5.25% NaOCl, then obturated with AH-26 sealer and either the lateral condensation (Groups C-E) or thermomechanical compaction technique (Groups A and B). Copper wire was placed coronally in contact with the gutta-percha in each tooth and, after immersion in 0.9% NaCl solution, a 10 volt dc voltage was connected between each tooth and a stainless steel electrode. The current flow in the circuit was observed for 45 days. One way ANOVA and Duncan's Multiple Range Test were used to compare Groups A-F at time intervals of 10, 20, 30 and 45 days and identify statistically significant differences.

RESULTS

Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine-driven NiTi files exhibited less leakage than hand-instrumented canals irrespective of obturation method.

CONCLUSIONS

Smear layer removal is beneficial to root canal sealing. Obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals.

Leakage of amalgam, composite, and Super-EBA, compared with a new retrofill material: bone cement

An in vitro leakage study was conducted to compare the root-end sealing ability of amalgam with cavity varnish, composite with dentin bonding agent, and Super-EBA with a new retrofill material: bone cement. Eighty single-rooted teeth were instrumented and obturated with gutta percha, resected and retroprepared. The teeth were then randomly divided into 4 groups of 20, with each group receiving one of the previously mentioned retrofill materials. The bone cement group was either etched or unetched. The teeth were immersed in silver nitrate and developer for leakage assessment. The teeth were grooved and split longitudinally to measure leakage. Statistical analysis showed that amalgam leaked significantly less than Super-EBA and unetched bone cement; composite leaked significantly less than Super-EBA. Amalgam was not statistically different from composite or etched bone cement. No significant difference between composite and both bone cements was noted, nor between both bone cements and Super-EBA.

Effect of soaking in Hank's balanced salt solution or milk on PDL cell viability of dry stored human teeth

This study was designed to evaluate the effect of soaking in either Hank's balanced salt solution (HBSS) or milk on periodontal ligament (PDL) cell viability in avulsed teeth. Dry storage times of 30, 60, and 90 min were evaluated. PDL cell viability was determined after removal of the cells from the root surfaces of extracted teeth using a modification of the procedure described by Nakashima (Arch Oral Biol 1991;36:655-63). After trypsinization and subsequent treatment in collagenase, the cells were stained with trypan blue, and viable and non-viable cells were counted using a hemocytometer and converted to percentages for statistical comparison. The results of this study demonstrated no significant difference in the number of viable cells with or without soaking in HBSS or milk at any of the dry storage times. In addition, there was no significant difference in PDL cell viability between the 30-and the 60-min dry periods. Although the soaking procedure had no obvious negative consequence, no significant improvement in PDL cell viability by the addition of this step was demonstrated under the conditions of this study.

The reliability of electric pulp test after concussion injury

Traumatic injuries to teeth present a difficult diagnostic problem with respect to determining the vitality of the affected teeth. Conventionally, a latency period of 4 to 6 weeks is proposed as the amount of time required for the return of a positive electric pulp test (EPT) response; however, this has been based on empirical data. The purpose of this study was to 1) determine a time frame during which a return of a reliable response to EPT may be measured, and 2) correlate this time frame with pulpal vascular changes that occur after traumatic injuries. Four canines from each of nine ferrets were used for this experiment (18 traumatized and 18 control teeth). A reproducible concussion injury was devised by releasing a known weight at a constant height above the facial surface of the experimental teeth. The EPT response was confirmed by the use of an EMG muscle recorder. Animals were killed at 24, 48 and 72 h and 6, 12 and 28 days after the injury and the teeth analyzed histologically. The histological sections showed an absence of inflammatory cells in both groups; however, according to the NIH image system, an increase in the number of vessels was detected in the experimental group when compared to the controls. In a majority of the cases, a positive response to the EPT returned within 12 days post concussion injury and as early as 10 days. In addition, a significant vascular change was accompanied with the loss of the EPT response. This study provided a reliable method by which concussion injuries may be studied using an animal model.

Luxation injuries

Luxation injuries range in severity from a mild blow to a more severe form, which can cause pulpal necrosis and additional sequelae. This article reviews the epidemiology and describes the various classifications, the appropriate treatment, and the various sequelae of luxation injuries.

Determining periodontal ligament (PDL) cell vitality from exarticulated teeth stored in saline or milk using fluorescein diacetate

One of the key factors for obtaining a favourable long-term prognosis in avulsed teeth is maintenance of the vitality of the periodontal ligament (PDL) cells. Most studies which have examined PDL cell vitality have used neutral red or trypan blue as stains. However, these stains have certain inherent disadvantages. The purpose of this paper was to (i) evaluate the use of saline and milk as storage media for PDL cells and (ii) determine the value of using fluorescein diacetate (FDA) as a staining medium for vital PDL cells on the root surface of avulsed teeth. Thirty-two single-rooted premolars were utilized from patients aged 13 to 28 years. Following atraumatic extraction, the teeth in the experimental groups were air dried for 10 min and then placed in either milk or saline for 120 min. Both control and experimental teeth were subjected to trypsinization procedures, staining with FDA, and haemocytometer readings to determine the number of vital cells. There was no statistically significant difference in the number of viable cells on the root surfaces of teeth after 2 h of storage in either milk or in saline. Furthermore, staining with FDA provided an excellent method by which to determine PDL cell vitality.

Management of avulsions

The treatment of the avulsed tooth provides a significant challenge to the dental practitioner. It is obvious that this particular dental injury poses a significant number of questions for both the researcher and the clinician. There will be most likely a continued interest to find the ideal treatment for this injury. As much as the dental literature has provided an improvement to the treatment of patients with avulsed teeth, however, there remains a significant number of clinically relevant questions that must be addressed before patients who sustain avulsion injuries can receive an acceptable long-term prognosis.

Anatomical study of the position of the mesial roots of mandibular molars

In order to determine the position of the anatomical apex of the mesial roots of the first and second molars, the horizontal distance from the outer surface of the buccal cortical plate to the apex and the vertical distance from the superior border of the neurovascular bundle to the apex were examined in 33 human cadaver mandible halves. The vertical distances were compared with measurements taken from periapical radiographs between the apex of each mesial root and the superior border of the mandibular canal prior to sectioning. The means of the horizontal buccal distances of the second molar were found to be significantly greater than those of the first molar. The means of the vertical distances of the second molar were found to be significantly less than those of the first molar. A high correlation was found between the vertical anatomic and radiographic measurements. In the majority of the sections, the neurovascular bundle was found in the lingual half of the mandible.

Cytotoxicity testing of a dentin bonding system

The cytotoxicity of a newly developed dentin bonding system was examined in African green monkey kidney cells and human embryonic lung cells. A tissue culture agar overlay procedure, a longitudinal study, and a cell replication assay were employed to evaluate cytotoxicity. Several of the components were discovered to be cytotoxic when tested individually in vitro. However, when used in the prescribed manner, little or no cytotoxic effect was elicited. The results of this study support further testing of these materials in vivo.

Marginal leakage of class V cavity preparations

Dentin-bonding materials, ferric oxylate (FO), addition reaction between N-phenylglycine and glycidyl methacrylate (NPG-GMA), and addition reaction product of pyromellitic acid dianhydride and 2-hydroxyethyl methacrylate (PMDM), were tested together for their ability to inhibit marginal leakage in Class V composite restorations in vitro. Sixteen experimental teeth were pretreated with FO, NPG-GMA, PMDM, and restored with composite. Sixteen control teeth were treated conventionally with composite. The teeth were then thermally cycled (5 and 55 degrees C) for 7 days, silver stained, and evaluated blindly for degree of marginal leakage on a scale of 0 (no leakage) to 7 (leakage into the pulp). The experimental group displayed significantly greater leakage values (p less than 0.01) than controls. The results of this study support the hypothesis that FO, NPG-GMA, and PMDM, together with composite inhibit marginal leakage.

Orthodontic movement of a horizontal root fractured tooth

A case report of an 8-year follow-up after orthodontic movement of a horizontally root fractured central incisor is presented.

Comparison of two self-administered field dependency measures

The present study examined the correlations between the recently developed group embedded-figures test (GEFT), the hidden-figures test Form-V, and the rod-and-frame test (RFT). 30 college males randomly selected from introductory and experimental psychology courses were administered the three measures of field dependency within a 2-wk. period. Intercorrelations among the three tests were significant ( rGEFT/RFT = –.691, p < .005; rHFT/RFT = –.476, p < .005; rGEFT/HFT = –.749, p < .005). A t test for related correlations indicated that the two correlations with the rod-and-frame test were significantly different ( t = 2.19, p < .025). The validity of the hidden-figures test as a measure of field dependency is questioned.