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PubMed2004

Effectiveness of a hydrophilic primer when different antimicrobial agents are mixed.

The purpose of this study was to determine whether different types of antimicrobial agents with hydrophilic primer applied to etched enamel surfaces will affect the shear bond strength (SBS) and the bracket/adhesive failure modes of metallic orthodontic brackets. Eighty noncarious human premolars were divided into four groups of 20 each. A composite resin (Transbond XT) was used to bond stainless steel brackets. Teeth in the first group were used as a control and bonded with standard procedures. For the other three groups, mixtures containing a hydrophilic primer (Transbond MIP) and one of three anti-microbial agents were prepared (Cervitec: in 1:2 ratio; chlorhexidine mouthwash and EC40 varnish in 1:1 ratio). These mixtures were applied to the etched enamel surfaces and thoroughly light cured for 20 seconds, and the brackets were bonded and light cured for 40 seconds. The SBS values of these brackets (Mpa) were recorded using a universal testing machine. Adhesive Remnant Index scores were determined after failure of the brackets. Data were analyzed using analysis of variance (ANOVA), Tukey honestly significant difference, and chi-square tests. Results of ANOVA revealed statistically significant differences in bond strengths among the various groups tested (P < .05). The bond strength values in these four groups compared favorably with those from other studies and the minimal bond strength values that are clinically acceptable. However, results of this study demonstrated that groups 1 (control) and 2 (Cervitec varnish) had higher SBS values than the other applications. Application of different antimicrobial agents may result in differences in the site of failure.

Analysis of Variance↗
PubMed2005

Effects of a chlorhexidine varnish on shear bond strength in indirect bonding.

The purpose of this study was to evaluate the effects of an antimicrobial varnish on the shear bond strength (SBS) of metallic orthodontic brackets bonded with an indirect bonding resin. For this purpose, 60 noncarious human premolars were divided into three equal groups. Group 1 was an indirect bonding control group and, after acid etching of the enamel, the brackets were indirectly bonded to the teeth with an indirect bonding resin. In group 2, before bonding, an antimicrobial varnish was painted on the etched enamel and indirect bonding was carried out as in group 1. In group 3, Transbond MIP primer and the antimicrobial varnish were thoroughly mixed in a 1:2 proportion, applied to the enamel surface, light cured for 20 seconds, and the brackets were direct bonded. A universal testing machine was used to determine the maximum load necessary to debond the brackets, the SBS values recorded, and the adhesive remnant index scores determined. Data were analyzed using analysis of variance (ANOVA), Tukey HSD, and chi-square tests. Results of ANOVA revealed statistically significant differences in the SBS among the various groups tested (P < .05). Indirect bonding of brackets with Sondhi Rapid Set after the application of the antimicrobial varnish showed significantly lower SBS when compared with both the group 2, indirect bonding control group, and the group 3, direct bonded-antimicrobial varnish group.

Acid Etching, Dental↗
PubMed1998

Effect of semi-annual applications of a chlorhexidine/fluoride varnish mixture on approximal caries incidence in schoolchildren. A three-year radiographic study.

Development and progression of approximal caries is still difficult to prevent and control even in societies with declining caries prevalence. In this study, a test group of 115 12-yr old children were treated semi-annually with a mixture (1:1) of a varnish containing 0.1% F (Fluor Protector) and 1.0% chlorhexidine (Cervitec). A reference group of 104 children received fluoride varnish treatment (Fluor Protector) semi-annually. Approximal caries was recorded from bitewing radiographs at baseline and after 3 yr. At baseline, total decayed and filled surfaces (DFS) including enamel caries were 1.79+/-2.36 in the reference group and 2.0+/-2.77 in the test group. After 3 yr, the mean approximal caries incidence including enamel caries was 3.01+/-3.74 and 3.78+/-4.32, respectively. The differences at baseline as well as after 3 yr were not statistically significant. The results showed that both groups had a comparatively low incidence of approximal caries during the experimental period, and suggest that a mixture of fluoride and antibacterial varnish had no additional preventive effect on approximal caries incidence compared with fluoride varnish treatments alone.

Anti-Infective Agents, Local↗
PubMed1998

Effects of root canal sealers on immunocompetent cells in vitro and in vivo.

Over the years of testing biocompatibility of endodontic filling materials, little attention has been paid to the potential adverse influences on the function of the immune system. Therefore, the purpose of this study was to investigate the extent to which extractable components of some commonly used root canal sealing materials (ERCS) may interfere with immunocompetent cells in vitro. The potential of these materials to cause delayed-type hypersensitivity (DTH) was also addressed in a rat model system. Extractable components were drawn in cell culture medium from freshly mixed or set material of AH 26. Grossman's sealer, Endomethasone, and Apexit. In-vitro assays included either spleen cells or rat pulp tissue cells that were released following enzymatic digestion with collagenase. Purified T cells for the pulpal cell assay were obtained from rat mesenteric lymph nodes. The effect of ERCS on the proliferation of concanavalin A (con A) stimulated spleen cell was measured by 3H-thymidine incorporation. Pulpal accessory cell function was monitored by the capacity of pulpal cells, pretreated with components of ERCS, to provide signals to con A stimulated T cells. DTH was tested after subcutaneous implantation of root canal sealers (RCS) in rats and challenge by ear injection. Pretreatment of pulpal cells with low dilutions of eluates from extracted AH 26 and Endomethasone resulted in a strong reduction of the T cell proliferation rate. The effect was considerably reduced (P < 0.01) when extracts of the solid material were employed. Extracts of Grossmans' sealer and Apexit affected T cell proliferation only to a limited extent in the pulpal cell assay. In general, assays on spleen cells showed a similar profile, although increased cell division was induced by Grossman's sealer at high eluate dilutions and a concentration-dependent decrease of cell division at lower concentrations of this material. ERCS evoked both immunosuppression and, in some instances, immunostimulation, but they did not release DTH.

Administration, Topical↗
PubMed2002

Cytotoxicity of resin-, zinc oxide-eugenol-, and calcium hydroxide-based root canal sealers on human periodontal ligament cells and permanent V79 cells.

AIM: The purpose of this study was to determine the cytotoxicity of three different types of root canal sealer on human periodontal ligament (PDL) cells and a permanent hamster cell line (V79 cells). METHODOLOGY: Set specimens from two resin based sealers (AH26 and AHPlus), three zinc oxide-eugenol-based sealers (Canals, Endomethasone and N2) and one calcium hydroxide-based sealer (Sealapex) were eluted with culture medium for 1, 2, 3 and 7 days. Cytotoxicity was judged using tetrazolium bromide reduction assay on human primary PDL cells and V79 cells derived from a Chinese hamster. RESULTS: The results showed that elutes from resin-based, zinc oxide-eugenol-based, and calcium hydroxide-based sealers were cytotoxic to primary human PDL cultures and V79 cells. Calcium hydroxide-based sealer was the least toxic sealer amongst the chemicals tested in both cultures. The cytotoxic response decreased in an order of N2 > Endomethasone > AH26 > AHplus > Canals > Sealapex. CONCLUSIONS: The sensitivity of toxicity depended on the materials tested and the cell culture system used. Thus, the use of both permanent and primary cells is recommended for screening of the cytotoxic effects of root canal sealers. In addition, the results confirmed that root canal sealers constantly dissolve when exposed to an aqueous environment for extended periods, possibly causing moderate or severe cytotoxic reactions. Use of calcium hydroxide-based material as a root canal sealer initially may result in a more favourable response to periradicular tissues.

Administration, Topical↗
PubMed2002

Influence of irrigants on the coronal microleakage of laterally condensed gutta-percha root fillings.

AIM: To assess in vitro coronal microleakage in extracted human teeth after root-canal treatment, using different endodontic irrigants. METHODOLOGY: Fifty teeth with single root canals were prepared and filled using the lateral condensation of gutta-percha and Endométhasone sealer. Canal preparation consisted of initial shaping of the coronal two-thirds with Gates-Glidden burs size 2 and 3, followed by preparation of the apical stop and step-back flaring with manual files. Each group (n = 10) was irrigated with the following solutions: I--1% NaOCl, II--1% NaOCl + 17% EDTA, III--2% chlorhexidine gel, IV--2% chlorhexidine gel + 1% NaOCl, and V--distilled water. After root-canal filling, the teeth were incubated at 37 degrees C for 10 days followed by 10 days immersion in human saliva and an additional 10 days in India ink. The teeth were cleared and maximum dye penetration was determined digitally in millimetres. Statistical analysis was carried out using the Kruskal-Wallis test. RESULTS: Least leakage occurred with 1% NaOCl + 17% EDTA (2.62 mm) and 2% chlorhexidine gel (2.78 mm) (P > 0.05). NaOCl (3.51 mm), distilled water (6.10 mm) and 2% chlorhexidine gel + 1% NaOCl (9.36 mm) gave increased leakage with a significant difference compared to NaOCl + 17% EDTA and 2% chlorhexidine gel, and compared to one another (P < 0.05). CONCLUSIONS: Under the condition of this study, irrigation method during root-canal treatment influenced coronal microleakage. NaOCl + EDTA and chlorhexidine gel allowed better sealing following root filling.

Administration, Topical↗
PubMed2003

Tissue reaction initiated by different sealers.

AIMS: To analyse the type and degree of inflammatory reaction initiated by four sealers. METHODOLOGY: Twenty-four root canals of Macaca mulatta monkeys were filled within the canal and eight were overfilled with AH26, Apexit, Endomethasone or Grossman's sealers. The result of the treatment was evaluated after 6 months by histological assessment of the periapical tissues. RESULTS: In the group of root canals filled within the root, no inflammatory reaction was detected in specimens of Apexit and Grossman's sealers, but the other two sealers initiated different degrees of lymphocytic/plasmocytic tissue reactions. Endomethasone initiated a mild lymphocytic/plasmocytic reaction in three of the nine cases and AH26 caused mild lymphocytic/plasmocytic infiltration in two of the seven cases. In the group of overfilled root canals, all four sealers initiated inflammatory reactions. The periapical tissue reactions of overfilled root canals were similar to reactions detected in cases filled within the canal. However, additional histological features developed in specimens of Endomethasone and AH26: Endomethasone initiated a foreign body-type granulomatous reaction around the sealer particles and AH26 particles were engulfed by macrophages. The overfilled root canals of Apexit and Grossman's sealers initiated only lymphocytic/plasmocytic reactions. CONCLUSIONS: This study suggests that sealers with different chemical compositions initiate different histological reactions. It also emphasizes the importance of confining root filling to the canal system because all sealers initiate inflammatory reactions when they are present in the apical tissues

Administration, Topical↗
PubMed2003

Rheological properties and biocompatibility of endodontic sealers.

AIM: To determine the flow characteristics and subcutaneous tissue reactions to five endodontic sealers. METHODOLOGY: The materials used were Procosol, AH26, Endomethasone, Sealapex and Endion. The sealers were prepared following the manufacturers' instructions, and 0.075 mL of each material was placed on a glass surface, which was then rotated 90 degrees. The samples were stored at 37 degrees C and 95% humidity. The displacement of the sealer was recorded by measuring the difference between its original position and the position recorded at 15 and 60 min. Three samples of each material were used. Two pockets were created in the back of Wistar rats, and one silicone tube, 1 mm in diameter and 1 cm in length, was implanted in each. One was filled with one of the materials under study, and the other empty tube was implanted as a control. Fourteen days after implantation, the animals were sacrificed, and samples of the skin containing the tubes were histologically processed. Histological and histomorphometric evaluations of the tissues adjacent to the open end of the tube were carried out the volume of tissue reaction was measured histomorphometrically according to standard stereological principles. Results were statistically analysed using analysis of variance and Duncan's test. RESULTS: The highest flow values were obtained with Sealapex and AH26. Time significantly affected the flow and the material (P < (1001). Procosol and Endion produced the most severe histological reactions: these were outlined by fibrous tissue; AH26. Endomethasone and Sealapex produced reactions of smaller size and with more moderately defined limits. CONCLUSIONS: The flow did not correlate with the degree of inflammatory response. Procosol and Endion produced the most severe tissue reactions, whereas Endomethasone, Sealapex and AH26 produced only minimum reactions.

Analysis of Variance↗
PubMed1998

Evaluation of the preservative properties of Thymus vulgaris essential oil in topically applied formulations under a challenge test.

The preservative properties of thyme essential oil (3%) with a known composition were evaluated in two types of final formulations, suitable for use as pharmaceutical or cosmetic vehicles, by means of a standard challenge test proposed by the latest European Pharmacopoeia. The required preservation efficacy criteria were satisfied against the bacterial strains, against the yeast in one of the formulations, but not against the mould strain involved in this study. Interactions between the essential oil compounds and other factors present in the final formulation might have influenced the activity of this essential oil, leading to an incomplete satisfaction of the criteria.

Administration, Topical↗
PubMed2001

Advances in disinfection testing and modelling.

AIMS: To develop a set of kinetic equations which more ably describe the disinfection process. METHODS AND RESULTS: A group of functions, the fat equations, based on the model used for the quantification of microbial inhibition, was produced. These functions introduce a limit to the numbers of micro-organisms capable of being disinfected. These new expressions were shown to be more general forms of currently-used (e.g. log-linear) disinfection models, and accommodate the lags and/or tails of non-linear log-survivor--time plots. An advance in the experimental procedures used to obtain disinfection data, using an optical density technique, was developed concomitantly. CONCLUSION: The methods of analyses (experimental and modelling) allow the researcher to examine, more ably, five-minute disinfection (or specific time disinfection tests) as well as the more important disinfection rate analyses. SIGNIFICANCE AND IMPACT OF THE STUDY: The fat equations are an improvement over commonly-used rate models of disinfection, which are shown to be special cases of these equations. This raises the question as to whether our current understanding of the kinetic basis of disinfection requires revision.

Chloramphenicol↗
PubMed2003

A model for the efficacy of combined inhibitors.

AIMS: The method of the sum of the fractional inhibitory concentrations (SigmaFIC) is used ubiquitously in the investigation of antimicrobial combinations. The inherent assumption of this simple equation is that in a mixture all antimicrobials have identical dose responses. The aim of this work was to analyse the outcome of removing this assumption. METHODS AND RESULTS: A model to describe the efficacy of combined inhibitors was produced which removed the assumption of identical dose responses. The results of several checkerboard experiments showed that the new model, termed the facomb was a more general form of the SigmaFIC method, but the features described by the SigmaFIC as either synergy or antagonism could be attributed to differences in the dose responses of antimicrobials in combination. Where the model failed to adequately describe experimental data it was suggested that these might be cases of true antagonism or synergy. CONCLUSIONS: The SigmaFIC methodology used to describe the effect of antimicrobial combinations (preservatives and antibiotics) is valid only when it is demonstrated that individual components of the mixture have identical dose responses. Otherwise the SigmaFIC method is invalid. Descriptions of antimicrobial synergy may simply be due to the mixing of antimicrobials with differing dose responses. SIGNIFICANCE AND IMPACT OF THE STUDY: Studies aimed at producing synergistic mixtures of antimicrobials, which ignore the dose response of the individual antimicrobials, may waste valuable research effort looking for a physiological explanation for an apparent synergy, where none, in-fact, exists. Conversely, mixing antimicrobials with very different dose responses might lead to mixtures with an 'apparent' synergy which may themselves be very useful therapeutically.

Anti-Bacterial Agents↗