A comparative evaluation of antimicrobial property of traditional and three alternative disinfectants on irreversible hydrocolloid impressions: An in vitro study.

Aim: The aim was to compare the efficacy of various herbal disinfectants on irreversible hydrocolloid impressions and to investigate the effectiveness of three herbal disinfectants and a chemical disinfectant against particular pathogens. Settings and Design: In vitro -a comparative study. Materials and Methods: The following methodology was followed to achieve the objectives. Four maxillary impressions were made for each selected patient with irreversible hydrocolloid impression material. The predisinfection swabs were taken from impression sites of teeth 17, 13, 27, and 23 (FDI system of tooth numbering). The impressions were immersed in all four different disinfectants such as 2% glutaraldehyde, Aloe vera solution, 50% neem oil, and apple vinegar solution, then the postdisinfection swabs were taken from the same sites 17,13,27,23 and then cultured onto sheep blood agar and examined for growth, and colony forming units (CFUs) of Streptococcus viridans, Streptococcus mutans, Streptococcus sanguis, and Actinomyces viscosus. The comparative analysis was done for the predisinfection and postdisinfection values in each study group. Statistical Analysis Used: Descriptive analysis, Kruskal Wallis test, Mann Whitney post hoc test, Wilcoxon signed rank test. Results: The results revealed that the mean CFUs of S. viridans, S. mutans, S. sanguis, and A. viscosus during postdisinfection samples were statistically significant when compared to predisinfection samples. Multiple comparison of the mean CFUs of all 4 microorganisms in the control group and in 50% Neem oil group was significantly lesser compared to A. vera and Apple Vinegar group. Conclusion: CFUs of S. viridans, S. mutans, S. sanguis, and A. viscosus significantly decreased in the 50% neem oil group as well as the control group. As a result, 50% Neem oil was a viable option for disinfecting alginate impressions.

Mechanical and Physical Properties of an Experimental Chemically and Green-Nano Improved Dental Alginate after Proven Antimicrobial Potentials.

OBJECTIVES: Impression materials could be a source of cross-contamination due to the presence of microorganisms from blood and saliva inside the oral cavity. Nevertheless, routinely performed post-setting disinfection could compromise the dimensional accuracy and other mechanical properties of alginates. Thus, this study aimed to evaluate detail reproduction, dimensional accuracy, tear strength, and elastic recovery of new experimentally prepared self-disinfecting dental alginates. METHODS: Two antimicrobial-modified dental alginate groups were prepared by mixing alginate powder with 0.2% silver nitrate (AgNO3 group) and a 0.2% chlorohexidine solution (CHX group) instead of pure water. Moreover, a third modified group was examined by the extraction of Boswellia sacra (BS) oleoresin using water. The extract was used to reduce silver nitrate to form silver nanoparticles (AgNPs), and the mixture was used as well in dental alginate preparation (BS + AgNP group). Dimensional accuracy and detail reproduction were examined as per the ISO 1563 standard guidelines. Specimens were prepared using a metallic mold engraved with three parallel vertical lines 20, 50, and 75 µm wide. Detail reproduction was evaluated by checking the reproducibility of the 50 µm line using a light microscope. Dimensional accuracy was assessed by measuring the change in length between defined reference points. Elastic recovery was measured according to ISO 1563:1990, in which specimens were gradually loaded and then the load was released to allow for recovery from the deformation. Tear strength was evaluated using a material testing machine until failure at a crosshead speed of 500 mm/min. RESULTS: The recorded dimensional changes between all tested groups were insignificantly different and within the reported acceptable values (between 0.037-0.067 mm). For tear strength, there were statistically significant differences between all tested groups. Groups modified with CHX (1.17 ± 0.26 N/mm) and BS + AgNPs (1.11 ± 0.24 N/mm) showed higher tear strength values compared to the control (0.86 ± 0.23 N/mm) but were insignificant from AgNO3 (0.94 ± 0.17 N/mm). All tested groups showed elastic recovery values that met both the ISO standard and ADA specifications for elastic impression materials and tear strength values within the acceptable documented ranges. DISCUSSION: The CHX, silver nitrate, and green-synthesized silver nanoparticles could be promising, inexpensive alternatives for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles could be a very safe, efficient, and nontoxic method, with the advantage of having a synergistic effect between metal ions and active chemical constituents of plant extracts.

Evaluation of the Efficacy of Novel Self Disinfectant Solution in Irreversible Hydrocolloid Impression Material - An Experimental Study.

Background: Irreversible hydrocolloid materials are widely used for both diagnostic and definitive impression procedures. Impressions can be disinfected by immersion or spraying in any compatible disinfectant. Disinfectants should not adversely affect the dimensional stability of the impression and physical properties of impression material and subsequent dental cast. Objective: The study aims to evaluate the efficacy of a hypochlorous disinfectant solution mixed with irreversible hydrocolloid on setting time, antibacterial efficacy, and dimensional stability. Methodology: Three groups were made with one control group and three alginate impression was made for each participants in the maxillary arch with 24-hours intervals between one another using the same brand of commercially available chromatic alginate. The working and setting time were noted. Bacterial swabs were collected using a dry sterile cotton swab in the mid palatal region. Dental casts were made using type III gypsum. Result: The working and setting time had significant differences whereas the dimension among the cast has no significant difference. Microbial growth analysis had distinct differences among the groups. Conclusion: The self disinfection method using a pioneer solution of hypochlorous HOCl (100 ppm) to mix the alginate impression material rather than the water with the same powder-liquid ratio prescribed by the manufacturer had the same dimensional stability with improved antimicrobial action.

Digital Analysis of the Dimensional Change Of an Irreversible Hydrocolloid Impression Material (Alginate) with Varying Storage Times.

AIM: The aim of this study was to digitally measure the dimensional changes in an irreversible hydrocolloid impression material (alginate) resulting from varying storage times under optimal storage conditions. MATERIALS AND METHODS: A single type V dental stone control cast was used to make 25 alginate impressions using perforated stock trays. The impressions were randomly assigned into five groups of five samples each (n=5 per group) with varying storage times: Group 1, poured at 15 minutes; Group 2, poured at one hour; Group 3, poured at 24 hours (one day); Group 4, poured at 72 hours (three days); Group 5, poured at 168 hours (seven days). All impressions were stored in sealed Ziploc® plastic bags with a wet paper towel (100% relative humidity) at room temperature and stored according to the assigned group storage times. All impressions were poured in type V dental stone according to the manufacturer's instructions. The casts were scanned with a digital 3D desktop scanner and saved as electronic stereolithography (.stl) files. Each .stl file of the scanned casts were superimposed on the .stl file of the control cast using Geomagic® Control X™ software. Three preselected fixed comparison measuring points (CMP) on each cast were compared to the control cast. Point one (CMP1) was on the midfacial surface of central incisor. Point two (CMP2) and point three (CMP3) were on the mesiobuccal proximal marginal ridge areas of third molars. The discrepancies between the files at each point were analysed with colour maps, and quantified (Table 1). The tolerance was set at ±10µm. CMP scores were analysed using one-way analysis of variance (ANOVA) and Kruskal-Wallis (K-W) non-parametric H tests. RESULTS: Average gap distances across groups ranged from 0.04mm (seven-day group) to 0.06mm (one hour and 24-hour groups). Colour maps indicated increased dimensional change with increased storage time up to one day. After three days, shrinkage up to 139µm was measured. ANOVA results for CMP1 (F[4,20] = 1.65, p = 0.020) and CMP3 (F[4,20] = 0.44, p = -0.78) were not statistically significant. Similarly, K-W results for CMP2 were not significant (χ2= 3.62, p = 0.46). CONCLUSIONS: Under optimal storage conditions, there were no significant dimensional changes in casts poured from alginate up to seven days.

A Promising Potential of Brown Algae Sargassum polycystum as Irreversible Hydrocolloid Impression Material.

This study aimed to investigate the potential use of brown algae Sargassum polycystum as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from Sargassum polycystum was prepared in three different compositions (14%, 15%, and 16%) and mixed with other standard components to form an alginate impression material. Prior to that, the purity of potassium alginate was quantified with Fourier Transform Infrared Spectroscopy (FTIR) analysis. As a control material, the alginate impression material from a commercially available product was used. All alginate impression materials were then applied to a die stone model. Dimensional accuracy was measured by calculating the mesiodistal width of incisors in the generated dental cast using a digital caliper 0.01 accuracy (five replications). In addition, to evaluate the dimensional stability, the impression results were poured at four different periods (immediately, 5 min, 10 min, and 15 min). An independent t-test was performed to compare the measurement results with p < 0.05 considered significant. Analytical results confirm that the impression material containing 15% potassium alginate gives the best dimensional accuracy similar to control (p > 0.05). Meanwhile, the optimal dimensional stability was produced in the impression material containing 16% potassium alginate. Our study suggested that brown algae Sargassum polycystum has a promising potential to be used as an alginate impression material in clinical application.

3D cone-beam C.T. imaging used to determine the effect of disinfection protocols on the dimensional stability of full arch impressions.

AIM: This study aimed to investigate the dimensional stability of irreversible hydrocolloid and polyvinylsiloxane (P.V.S.) impressions after exposure to four commercial disinfectants using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Two different impression materials were tested: irreversible hydrocolloid and P.V.S. Four disinfection solutions were applied: BirexSE, Opti-Cide3, COEfect MinuteSpray, and CaviCide Spray. Distilled water was used as a control group. Each solution remained in contact with the impression for 5 min. Additional contact time of 5 min compromises time for scanning. The materials were evaluated for dimensional stability after the impression of a maxillary complete edentulous template via CBCT before and after being in contact with the disinfectant agents. Measurements were assessed on the digital models from A-B, B-C, and C-A points. Paired analyses (Wilcoxon Signed Rank test or paired Student's t-test) were used to analyze each measurement before and after the contact with the disinfectant agents. The variance for each measurement was also analyzed via a one-way analysis of variance or Kruskal-Wallis. RESULTS: Overall, there were no statistical differences among the points measurements in the irreversible hydrocolloid or P.V.S. between initial and final assessments (p > 0.05). The used disinfectant agents in this study did not influence each measurement's variation on irreversible hydrocolloid or P.V.S. (p > 0.05). All agents showed an effect on the dimensional stability of both impression materials. The differences in the three dimensions ranged between 0.34 and 1.54%. CONCLUSION: Within 10 min of removing the impression from the master cast, is study's findings indicated that the four commercially available disinfectants did not influence the dimensional stability of irreversible hydrocolloid or P.V.S. Further studies should be performed to elucidate the antimicrobial effect of these solutions applied as a spray on the surface of irreversible hydrocolloid and P.V.S. impressions.

Antimicrobial Efficacy of Irreversible Hydrocolloid Impression Impregnated with Silver Nanoparticles Compared to Surface Disinfected Impressions - An In vivo Study.

BACKGROUND: Routine disinfection procedures have shown to cause incomplete disinfection and detrimental effects on dimensional properties of the impression. Hence, self-disinfecting impression materials impregnated with antimicrobial agents were developed. PURPOSE: The purpose is to evaluate the antimicrobial efficacy of silver nanoparticles (AgNPs) impregnated in irreversible hydrocolloid (IH) impression material in in vivo conditions. MATERIALS AND METHODS: This study comprised of four groups-IH impressions disinfected by immersion in 2% glutaraldehyde, IH impregnated with AgNPs of sizes 80-100 nm and 20-30 nm, nondisinfected impressions as control. Five impressions were made for each group and a total of 20 impression samples were made. The antimicrobial action of each sample was assessed by counting the number of colony forming units and by disc diffusion method. RESULTS: The results were obtained and the data were statistically analyzed by Kruskal-Wallis test and tabulated. The results revealed that AgNPs of size 80-100 nm when impregnated in irreversible impression material showed effective antimicrobial action. CONCLUSION: The anti-microbial action of 80-100 nm AgNP impregnated IH impressions is comparable to that of impressions disinfected by immersion in 2% glutaraldehyde for 10 min.

An evaluation of antimicrobial potential of irreversible hydrocolloid impression material incorporated with chitosan.

AIM: To evaluate the antimicrobial potential of irreversible hydrocolloid impression material manipulated using chitosan impregnated solution at various time intervals. SETTING AND DESIGN: Evaluative invivo study design. MATERIALS AND METHODS: Maxillary impressions made for 20 dentulous volunteers using irreversible hydrocolloid impression material manipulated using distilled water as control and using 1% chitosan impregnated solution as test group using stock metal trays with one-week interval. Bacterial samples were collected using dry sterile cotton swab in the mid-palatal region at the time intervals of 0, 10, 20 minutes. Bacterial swabs were inoculated on nutrient agar media and incubated at 37° C for 24 hours. Bacterial colonies were counted with the aid of colony counter. STATISTICAL ANALYSIS USED: The resultant data was subjected to statistical analysis using repeated measures ANOVA and independent t test. RESULTS: Adding water soluble chitosan to irreversible hydrocolloid impression material resulted in superior antimicrobial activity. With the passage of time there was a significant decrease in the microbial colony count upto 10min (p=0.016). However, the rate of decrease of microbial colony count was statistically insignificant between the samples collected at 10 and 20 min. CONCLUSION: Incorporation of water soluble chitosan to irreversible hydrocolloid impression material showed significant antimicrobial activity in 10 minutes.

Influence of time, temperature and humidity on the accuracy of alginate impressions.

BACKGROUND: The goal of the current in vitro study was to assess the dimensional accuracy of dental impressions when stored at different times, temperature and humidity. METHODS: Impressions were poured to an aluminium triangular die and three teeth placed at the three corners of the die. A total of 130 impressions were made, in which 10 were poured immediately following manufacturers' instructions and the remaining 120 specimens were divided into two groups on the basis of relative humidity during storage. Group-1: 100%, Group-2: 50% relative humidity. Impression was poured with type IV gypsum. The below points were chosen to determine the length between in each of the specimens using the traveling microscope with 10x magnifications after 24 hours of model recovery for calculating the effect of changes in storage conditions- relative humidity, temperature and delay in pouring the impressions, on dimensional accuracy. RESULTS: Analysis of the results revealed that the casts achieved by pouring alginate impressions without delay were most accurate than the delay pouring. With the increase in temperature and time, the distance between the points increased and the casts obtained were bigger. CONCLUSION: Irreversible hydrocolloids should be poured immediately for optimum dimensional stability.

Effect Of Lignocaine Addition On The Properties Of Irreversible Hydrocolloid Impression Material.

BACKGROUND: Irreversible hydrocolloid impression materials have been a staple in dentistry and useful for the fabrication of dental prosthesis. Gagging is most commonly experienced during maxillary impression making, which may affect the clinical management of the patient. Different techniques have been described to alleviate this problem. One of them is mixing lignocaine local anesthetic solution in irreversible hydrocolloid impression material before making the impression. The objective of this study was to evaluate the effect of lignocaine addition in irreversible hydrocolloid impression on the properties of irreversible hydrocolloid impression materials. METHODS: Irreversible hydrocolloid was mixed with water (Control group) or water and adrenalin (Lidocaine hydrochloride) (Experimental group). Compressive strength, tear strength and setting time were measured according to ISO1567 and ANSI/ADA specifications 18. The structural analysis of both groups was also evaluated by Fourier Transform Infrared Spectroscopy (FTIR). RESULTS: In the experimental group, insignificant decrease was observed in compressive and tear strength of irreversible hydrocolloid (p>0.05). There was significant (p<0.05) increase in setting time of irreversible hydrocolloid impression material. FTIR analysis indicated no change in chemistry of irreversible hydrocolloid before and after setting. CONCLUSIONS: Addition of lignocaine in irreversible hydrocolloid impression material may result in control of gag reflex without affecting its mechanical and chemical properties.

Evaluation of efficacy of Aloe Vera as a Disinfectant by Immersion and Spray methods on Irreversible Hydrocolloid Impression Material and its Effect on the Dimensional Stability of Resultant Gypsum Cast - An in Vitro Study.

The need to use a natural alternative for disinfecting dental impression materials, which should be biocompatible and effective, led us to evaluate the efficacy of Aloe vera as a disinfectant by immersion and spray method on alginate impression material and its effect on the dimensional stability of the resultant gypsum cast. The efficacy of the disinfection procedures against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans was evaluated by determining the number of colony-forming units (CFU) recovered after disinfection of alginate discs inoculated with 1x106 CFU for defined intervals with aloe vera solution (99.96%). Dimensional stability was determined from the mean percentage deviation of three measurements that were taken between the fixed points on the casts using a traveling microscope and compared with corresponding measurements from the master model and controls. Statistical analysis of data was determined by analysis of variance. We found out that there is a mean percentage reduction in colony count of S. aureus, P. aeruginosa, and C. albicans after 3 minutes of immersion in aloe vera and after 3 minutes spray disinfection. Complete elimination of all the microorganism cells after 7 min immersion and spray disinfection. There was a statistically significant difference in the increase of the mean anteroposterior (AP) and cross arch (CA) dimension after 3 and 7 minutes immersion in aloe vera. Spraying with aloe vera for 7 minutes was proved to be the most effective disinfection procedure without altering dimensional stability.

Does the size matter? Evaluation of effect of incorporation of silver nanoparticles of varying particle size on the antimicrobial activity and properties of irreversible hydrocolloid impression material.

OBJECTIVES: The main objective of the present in vitro study is to evaluate the antimicrobial activity and properties of irreversible hydrocolloid impression material incorporated with silver nanoparticles of varying size at different concentrations. METHODS: Silver nanoparticles of 80-100, 50-80, 30-50 and 10-20nm size were added to irreversible hydrocolloid impression material at 0.5, 1.0, 2.0 and 5.0wt%. Antimicrobial activity of the silver nanoparticle incorporated irreversible hydrocolloid was measured using disk diffusion method. The gel strength, flow, gelation time and permanent deformation were measured according to American Dental Association specification #18. Data were analyzed using analysis of variation at a confidence interval of 95% (α=0.05). RESULTS: Silver nanoparticles of 80-100nm size have imparted superior antimicrobial activity to the irreversible hydrocolloid in a dose-dependent manner whereas finer nanoparticle size did not exhibit any antimicrobial activity. The addition of silver nanoparticles did not alter the properties of irreversible hydrocolloid at 0.5 and 1.0wt% whereas at higher concentrations significant differences in flow, gelation time and strength were observed. SIGNIFICANCE: The results of the present study indicate that silver nanoparticles of size range 80-100nm are superior in imparting antimicrobial activity to irreversible hydrocolloid compared to finer particle size range.

Surface Detail Reproduction and Dimensional Stability of Contemporary Irreversible Hydrocolloid Alternatives after Immediate and Delayed Pouring.

PURPOSE: To overcome the poor dimensional stability of irreversible hydrocolloids, alternative materials were introduced. The dimensional changes of these alternatives after delayed pouring are not well studied and documented in the literature. The purpose of the study is to evaluate and compare the surface detail reproduction and dimensional stability of two irreversible hydrocolloid alternatives with an extended-pour irreversible hydrocolloid at different time intervals. MATERIALS AND METHODS: All testing were performed according to the ANSI/ADA specification number 18 for surface detail reproduction and specification number 19 for dimensional change. The test materials used in this study were newer irreversible hydrocolloid alternatives such as AlgiNot FS, Algin-X Ultra FS, and Kromopan 100 which is an extended pour irreversible hydrocolloid as control. The surface detail reproduction was evaluated using stereomicroscope. The dimensional change after storage period of 1 h, 24 h, and 120 h was assessed and compared between the test materials and control. The data were analyzed using one-way ANOVA and post hoc Bonferroni test. RESULTS: Statistically significant results (P < 0.001) were seen when mean scores of the tested materials were compared with respect to reproduction of 22 µm line from the metal block. Kromopan 100 showed statistically significant differences between different time intervals (P < 0.001) and exhibited more dimensional change. Algin-X Ultra FS proved to be more accurate and dimensionally stable. CONCLUSIONS: Newer irreversible hydrocolloid alternative impression materials were more accurate in surface detail reproduction and exhibited minimal dimensional change after storage period of 1 h, 24 h, and 120 h than extended-pour irreversible hydrocolloid impression material.

Evaluation of Antibacterial Effect and Dimensional Stability of Self-disinfecting Irreversible Hydrocolloid: An in vitro Study.

AIM: This study evaluated the antibacterial activity and dimensional stability of irreversible hydrocolloids mixed with different concentrations of chlorhexidine gluconate instead of water. MATERIALS AND METHODS: Experimental specimens (45 specimens) were prepared and allocated into three groups of 15 each. Group I: Impression material mixed with distilled water served as control. Groups II and III were prepared with 0.12 and 0.2% chlorhexidine gluconate solution, respectively. Specimens in each group were subjected to tests for dimensional stability. For antimicrobial activity, 30 specimens were prepared and allocated into three groups of 10 each named as group I (control), group II (0.12% chlorhexidine gluconate), and group III (0.2% chlorhexidine gluconate) similar to specimens for dimensional stability. Statistical analysis was performed using a one-way analysis of variance (ANOVA) and Tukey test. RESULTS: Zones of inhibition were observed around test specimens, but not around control specimens; there was a significant intergroup difference in the diameters of the inhibition zones. In the test for dimensional stability, no significant differences were detected among groups, and the accuracy was clinically acceptable. CONCLUSION: Irreversible hydrocolloid impression material mixed with chlorhexidine exhibits varying degrees of antibacterial activity without influencing the dimensional stability of set material. CLINICAL SIGNIFICANCE: Many contagious diseases can be prevented by practical control of infection in the dental office. Chlorhexidine gluconate, as a mixing liquid, ensures disinfection of impression, and this method of disinfection is more convenient and avoids extra effort as in other disinfection techniques.

Wax Lining in an Impression Tray and Accuracy in Gypsum Cast Fabrication.

PURPOSE: Controversy exists as to whether lining a metal-perforated impression tray with wax will yield a distorted irreversible hydrocolloid impression. Two current textbooks have completely different recommendations, but there is no evidence to support either theory. This project evaluates distortion in gypsum casts that have been prepared from wax-lined and unlined metal impression trays. The purpose of this study was to assess the influence of wax on the border and in the palate of metal-perforated impression trays on the dimensional stability of the resulting irreversible hydrocolloid impression. MATERIALS AND METHODS: A dentaform was prepared with marks on the cusp tips of teeth 6 and 11 and distobuccal cusps of teeth 2 and 15. Using a standard maxillary rim lock impression tray, alginate impressions were made using a dentaform with no wax lining, wax lining the border of the tray, and wax lining the border and the palate (n = 10). Casts were randomized. Six measurements were taken using a stereographic measuring microscope, from tooth #6 to #11, #11 to #15, #15 to #2, #2 to #6, #6 to #15, and #2 to #11. An acrylic template was used to position the cast in a reproducible position on the microscope. RESULTS: Trays lined with wax on the border and the palate yielded casts with significantly different dimensions when compared to those poured from unlined or border-lined trays (p < 0.05). Casts produced from unlined and border-lined trays were not significantly different in dimension from the dentaform (p > 0.05). CONCLUSION: There is no difference between the metal tray with no wax, the metal tray with a wax around the border, and the dentaform. The clinician can make irreversible hydrocolloid impressions using wax on the periphery or without wax on the periphery and feel confident that the impression has not been compromised in its ability to accurately reproduce the maxillary arch when used. Caution should be exercised when adding wax to the palate of the impression tray.

Antibacterial efficacy and effect of Morinda citrifolia L. mixed with irreversible hydrocolloid for dental impressions: A randomized controlled trial.

AIM: This study aimed to evaluate whether the extract of Morinda citrifolia L. mixed with irreversible hydrocolloid powder decreases microbial contamination during impression making without affecting the resulting casts. MATERIALS AND METHODS: Twenty volunteers were randomly divided into two groups (n = 10). Group A 30 ml extract of M. citrifolia L diluted in 30 ml of water was mixed to make the impression with irreversible hydrocolloid material. Group B 30 ml deionized water was mixed with irreversible hydrocolloid material to make the impressions following which the surface roughness and dimensional stability of casts were evaluated. RESULTS: Extract of M. citrifolia L. mixed with irreversible hydrocolloid decreased the percentage of microorganisms when compared with water (P < 0.001) but did not affect the surface quality or dimensional stability of the casts. CONCLUSION: Mixing the extract of M. citrifolia L. with irreversible hydrocolloid powder is an alternative method to prevent contamination without sacrificing impression quality.

Evaluation of the relation of maxillary canine and edge of central incisor to incisive papilla in Indian population with respect to arch form.

Finding the most suitable position for artificial anterior teeth in the absence of pre-extraction records presents a new challenge with every denture and has resulted in a variety of measurements. It encompasses the knowledge of anatomy and physiology of oral tissue. In this study, the relation between anatomical landmarks the tips of the maxillary canines, edge of central incisor and center of incisive papilla was evaluated and compared with respect to arch form in Indian population. Arch forms were accessed by their morphological description as square, tapering or ovoid arch. Measurements on the casts were recorded for incisive papilla and maxillary central incisor distance, by digital vernier caliper and photographic technique was used to record the relation between tips of the canine and the centre of the incisive papilla. The mean distance between edge of central incisor to center of incisive papilla for square arch, oval arch and tapered arch was found as 9.667, 9.991 and 10.912 mm respectively. When all the 300 casts were taken together, it indicated that 51.3 % of intercanine lines passed through the center, 18.1 % of inter canine lines passed posterior and 30.6 % of the intercanine lines passed anterior to the center of incisive papilla. χ(2) (Chi square) values concluded they differ significantly and significant number of intercanine lines crossed through the center of the incisive papilla irrespective of the arch form.

Prosthodontic rehabilitation of patient with flabby ridges with different impression techniques.

A fibrous or flabby ridge is a superficial area of mobile soft tissue affecting the maxillary or mandibular alveolar ridges. It can develop when hyperplastic soft tissue replaces the alveolar bone and is a common finding particularly in the upper anterior region of long term denture wearers. Masticatory forces can displace this mobile denture-bearing tissue, leading to altered denture positioning and loss of peripheral seal. Forces exerted during the act of impression making can result in distortion of the mobile tissue. Unless managed appropriately by special impression techniques, such 'flabby ridges' adversely affect the support, retention and stability of complete dentures. This paper presents three case reports for prosthodontic rehabilitation of patient with flabby ridges with three different impression techniques.

Effectiveness of mouthrinses and oral prophylaxis on reduction of microorganisms count in irreversible hydrocolloid impression: an in vivo study.

Dental impressions, contaminated with saliva, blood, plaque, are potential source of infection. All impressions should be disinfected after their removal from mouth to prevent cross contamination. Different methods have been tried to disinfect the commonly used irreversible hydrocolloid impression material, but they have been shown to influence the dimensional stability and surface detail of the impression which ultimately affects the precision of the final prosthesis. The aim of this study was to evaluate the efficacy of pre-procedural oral prophylaxis and mouthrinses in reducing the overall microbial load intraorally as well as on alginate impression surface. A total of 60 positive cases selected from 100 subjects who were partially edentulous and above 18 years of age and without medical or pharmacotherapy histories were studied over a period of 18 months, from outpatient clinic of Department of Prosthodontics, GNIDSR. Alginate impressions, before and after prophylaxis were examined microbiologically for the persistence of test microorganisms on the untreated (control group) and the impressions made after treatment. The data were statistically analyzed by the Student t test to assess the effectiveness of the procedure and also the comparative effectiveness of oral prophylaxis and commonly used mouthrinses. The results showed that the impressions were safer when made after oral prophylaxis and/or mouthrinses.

Microbiological assessment of the effectiveness of chlorhexidine mouthrinse before taking impressions of the oral cavity / Avaliação microbiológica da eficácia do bochecho de clorexidina prévio à moldagem da cavidade bucal

PURPOSE: The aim of this study is to assess the reduction of microbial load that adhered to irreversible hydrocolloid impressions obtained after rinsing with 0.12% and 0.2% chlorhexidine solutions. METHODS: The study consisted of 24 participants (48 dental arch impressions) equally divided into two groups: Group 1 (0.12% chlorhexidine) and Group 2 (0.2% chlorhexidine). The impressions were taken using Hydrogun® irreversible hydrocolloid before (control) and after (experimental) a single 10 mL mouthrinse of chlorhexidine for 1 minute. Each impression was placed in a sterile beaker containing 250 ml of saline. The microbiological analysis of the storage solution was carried out using BHI Agar culture medium. The plates were incubated for 24 hours, followed by a CFU (Colony Forming Units) count. The data were analyzed using the Wilcoxon's t test. RESULTS: There was a reduction in the degree of contamination of the impressions after rinsing with the antimicrobial mouth rinses at both concentrations when compared with the control group. There was a statistically significant difference when the effectiveness of the two concentrations used was compared. CONCLUSION: Therefore, using a chlorhexidine rinse prior to obtaining irreversible hydrocolloid impressions reduces contamination and is more efficient at the 0.2% concentration.

OBJETIVO: O objetivo deste estudo é avaliar a redução da carga microbiana aderida nos moldes de hidrocolóide irreversível obtidos após bochecho com clorexidina nas concentrações 0,12% e 0,2%. METODOLOGIA: O estudo incluiu 24 participantes (48 moldes de arcadas dentárias) divididos igualmente em dois grupos: Grupo 1 ( clorexidina 0,12%) e Grupo 2 (clorexidina 0,2%). As arcadas foram moldadas com hidrocolóide irreversível Hydrogun® antes (controle) e após (experimental) bochecho único com 10 mL de clorexidina nas concentrações específicas de cada grupo durante 1 minuto. Cada molde foi acomodado em bécker estéril contendo 250 mL de soro fisiológico. A partir dessa solução, realizou-se análise microbiológica em meio de cultura BHI Ágar. As placas foram submetidas a um período de incubação de 24 h oras, seguida de contagem das UFC (Unidades Formadoras de Colônias). Os dados foram submetidos à análise estatística aplicando o teste t de Wilcoxon. RESULTADOS: Observou-se redução do grau de contaminação dos moldes obtidos após bochecho com o antimicrobiano nas duas concentrações, em relação ao grupo controle e, também, diferença estatística significativa quando comparadas a eficácia das duas concentrações utilizadas. CONCLUSÃO: O bochecho de clorexidina prévio à obtenção de moldes de hidrocolóide irreversível reduz a contaminação e com melhor eficácia na concentração 0,2%.