Panagiotis Beltes

Removal Efficiency of Calcium Hydroxide Dressing from the Root Canal

The aim of this study was to investigate whether differences in the composition of calcium hydroxide (Ca(OH)2) preparations influence the removal efficiency of irrigation solutions used in combination with filing of the canal. Three Ca(OH)2 preparations were used: Calxyl, Pulpdent paste, and chemically pure Ca(OH)2 mixed with distilled water. Fifty-one single-rooted extracted human teeth were prepared with a step-back technique and divided into groups A, B, and C. In each group, 15 teeth were assigned to each Ca(OH)2 preparation while the remaining two served as positive and negative controls. Each group of treated teeth was divided into three subgroups of five teeth each: subgroup I--canals were irrigated with saline, filed with a #25 file, and finally flushed with saline; subgroup II--canals were irrigated with NaOCl, filed with a #25 file, and finally flushed with NaOCl; and subgroup III--canals were irrigated with NaOCl, filed with a #25 file, and finally flushed with tetrasodium EDTA. Canal sections were then photographed, and the percentage ratios of Ca(OH)2 coated area to the total canal surface area were calculated by image processing analysis. Results revealed: (a) none of the methods efficiently removed all dressing from the walls, and (b) concentration of the paste used had little effect on the efficacy of the methods applied for the removal of the dressing. Excipients (i.e. methylcellulose contained in Pulpdent) possibly effect retention of Ca(OH)2.

Long-Term Evaluation of the Influence of Smear Layer Removal on the Sealing Ability of Different Sealers

The purpose of this study was to examine the effect of the smear layer on apical microleakage over 16 wk. One hundred and four extracted human teeth were assigned to four groups treated as follows: group A1--smear layer was left intact and canals were obturated with gutta-percha and Roth 811; group A2--smear layer was left intact and canals were obturated with gutta-percha and AH26; group B1--smear layer was removed and canals were obturated with gutta-percha and Roth 811; and group B2--smear layer was removed and canals were obturated with gutta-percha and AH26. Microleakage was measured by the electrochemical method. In parallel, 12 teeth were examined under a scanning electron microscope. The results indicated that the smear layer removal resulted in a statistically significant reduction of microleakage values in groups obturated with AH26. The presence or absence of smear layer had no significant effect on the sealing ability of Roth 811.

In vivo comparison of the biocompatibility of two root canal sealers implanted into the subcutaneous connective tissue of rats

The purpose of this study was to evaluate the in vivo biocompatibility of Apexit (a calcium hydroxide) and Pulp Canal Sealer (a classic zinc oxide-eugenol), root canal sealers, after implantation in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted into specific dorsal subdermal tissues sites. Implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Severe inflammatory reactions with differing extensions of necrosis were observed with Apexit on the 5th and 15th days. The intensity of the reaction had diminished by the 60th day, and this reduction continued progressively through the 120th day. It was characterized by the presence of connective tissue with a few macrophages. Moderate to severe inflammation with confined areas of necrosis was observed in the Pulp Canal Sealer specimens on the 5th day. The intensity of the reaction diminished by the 15th, 60th, and 120th days, but remained slightly greater than Apexit through longterm observation periods.

Spectrophotometric analysis of coronal discolouration induced by grey and white MTA

AIM To evaluate the specific alterations in tooth colour with white and grey MTA when used to fill pulp chambers. METHODOLOGY Forty-five fully developed, intact, mandibular third molars were sectioned 1 mm below their cemento-enamel junction (CEJ). Their pulp chambers were chemo-mechanically debrided, and the specimens were randomly assigned into three groups: Group 1-white MTA (Angelus(™)), Group 2-grey MTA (Angelus(™)) and Group 3-negative control (unfilled). During the experimental period, specimens were immersed in vials containing distilled water up to the CEJ (37±1 °C). Spectral reflectance lines were recorded by utilizing a UV-vis spectrophotometer equipped with an integration sphere in the visual spectrum, at baseline, 1 week and 1, 2 and 3 months after placement of the materials. Data were transformed into values of the CIE L*a*b* colour system, and the corresponding ΔΕ values were calculated. The results were analysed using two-way mixed anova models, whilst pairwise comparisons were conducted with Bonferronis method at P < 0.05 level of significance. RESULTS Both types of MTA induced significant decreases in L*, a* and b* values. The colour change was greater with grey MTA. Grey MTA led to clinically perceptible crown discolouration after 1 month, whilst the total colour change caused by white MTA exceeded the perceptible threshold for the human eye after 3 months. CONCLUSIONS The application of both grey and white MTA formulations induced a decrease in lightness and reduction in redness and yellowness in teeth. The present findings suggest that application of grey MTA in the aesthetic zone should be avoided, whilst white MTA should be used with caution when filling pulp chambers with the materials.

Antiproliferative Effect of Mineral Trioxide Aggregate, Zinc Oxide-Eugenol Cement, and Glass-Ionomer Cement Against Three Fibroblastic Cell Lines

An important requirement for dental materials placed in direct contact with living tissues is biocompatibility. The purpose of this study was to evaluate the antiproliferative activity of three dental materials (mineral trioxide aggregate, zinc oxide-eugenol cement, and glass-ionomer cement) against a panel of established fibroblastic cell lines (L929, BHK21/C13, and RPC-C2A). The materials were prepared according to the manufacturers instructions and were tested in insert wells for 12, 24, and 48 h. Cell number fraction was estimated by the sulforhodamine-B assay, in reference to controls. The degree of antiproliferative effect in ascending order was mineral trioxide aggregate, glass-ionomer cement, and zinc oxide-eugenol cement in all cell lines tested.

Experimental study of the biocompatibility of a new glass-ionomer root canal sealer (Ketac-Endo)

Ketac-Endo, a new glass-ionomer cement for endodontic use as root canal sealer, and Tubli-Seal were tested for tissue biocompatibility in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted subcutaneously. The implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Mild inflammatory reaction was observed with Ketac-Endo on the 5th day. The connective tissue was infiltrated with plasma cells. Lymphocytes and macrophages were observed. The intensity of the reaction diminished by the 15th day, and this reduction continued progressively through the 60th and 120th days. Severe inflammation with differing extensions of necrosis was observed with Tubli-Seal on the 5th and 15th days, and the material remained irritating even after long-term implantation periods (60 and 120 days).

Cytotoxic effects of different concentrations of neutral and alkaline EDTA solutions used as root canal irrigants

The cytotoxic effects of neutral and alkaline EDTA solutions were evaluated and compared with those of sodium hypochlorite solution using an established cell line: L929. Cytotoxicity was assessed by a quantitative technique at five observation periods (1, 3, 6, 12, and 24 h). All tested agents showed moderate to severe cytotoxicity in the present experimental model in a concentration-dependent manner.

Inductive effect of native dentin on the dentinogenic potential of adult dog teeth

Autogenous dentinal matrix was exposed to the pulp cells of adult dogs in order to determine whether the mature pulp cells possess the ability to differentiate into odontoblast-like cells as a direct response to known inductive influences. The pulps of molars, premolars, and canines of three dogs (2 to 4 yr old) were mechanically exposed through buccal class V cavities. Pieces of demineralized or native dentin and predentin were implanted in the pulp sites for periods of 2 to 6 wk. The reactions were analyzed by light microscopy. Induction of dentin formation was observed only after native dentin implantation; either as early response to exposure of predentinal surfaces or around mineralized dentin after 3 postoperative wk. Encapsulation by fibrous connective tissue or matrix degradation was seen around demineralized dentin implants. A characteristic enhancement of circumferential pulpal dentin deposition around the implantation site was demonstrated after native dentin exposure to light and scanning electron microscopic examination. These data indicate that specific inductive influences given by the native but not the acid-conditioned dentin, when it is exposed to the pulp environment of adult teeth, are able to direct differentiation of odontoblast-like cells and to enhance the biosynthetic activity of primary odontoblasts.

In vitro release of hydroxyl ions from calcium hydroxide gutta-percha points.

In endodontic practice, calcium hydroxide is widely used for a number of reasons associated with its high pH. The purpose of the present study was to determine in vitro the alkalizing potential of newly introduced calcium hydroxide gutta-percha points that are proposed for temporary filling of root canals. The materials tested were: calcium hydroxide gutta-percha points; chemical pure calcium hydroxide powder mixed with distilled water; and Reogan rapid, a nonsetting calcium hydroxide preparation. The materials were placed into dialysis tubing and transferred into plastic vials containing bidistilled water. Measurements were taken by a digital pH meter after 10, 20, and 30 s; 1, 15, and 30 min; and 1, 2, 3, 24, 48, 72, 96, and 120 h. The calcium hydroxide containing gutta-percha points showed a significantly lower alkalizing potential than Reogan rapid and calcium hydroxide mixed with distilled water (p < 0.05).

Endodontic treatment in three cases of dens invaginatus

Three cases of dens invaginated teeth with periapical lesions are presented in this article. In the first case the maxillary canine was treated with conventional endodontic treatment. The second and third cases, in mandibular and maxillary central incisors respectively, were treated surgically. Six months postoperatively all cases appeared radiographically to be improved.