Investigating In Situ Expression of Neurotrophic Factors and Partner Proteins in Irreversible Pulpitis.

INTRODUCTION: In situ assessments of neurotrophic factors and their associated molecular partners have not been explored to date, particularly in humans. The present investigation aimed to explore the expressional dysregulation of neurotrophic factors (nerve growth factor [NGF], brain derived neurotrophic factor [BDNF], and NT4/5), their receptors (TrkA and TrkB), and their modulators (USP36 and Nedd4-2) directly in irreversibly inflamed human pulp tissues. METHODS: Forty samples each of healthy and irreversibly inflamed pulp were extirpated for the study. Immunohistochemical examinations were carried out for the anatomic changes and expression of neurotrophic factors and partner proteins. Expression was digitally quantified using the IHC profiler module of ImageJ and deduced as optical density. Statistical analyses were carried out by GraphPad Prism. RESULTS: Decrease in nuclear and vessel diameters was observed in irreversibly inflamed pulp tissues. NGF and BDNF were found to be significantly upregulated in symptomatic irreversible pulpitis (SIP), whereas no significant difference was observed in the expression of TrkA and TrkB. Expression of Nedd4-2, USP36, and TrkA was found positively correlated with the NGF in healthy pulp tissues. However, in SIP, positive correlation was only observed between the expression of USP36 and NGF. Among the ligands, BDNF expression was found positively correlated with NGF in healthy pulp but not with NT4/5. In the case of SIP, no correlation was observed between any neurotrophic factors. CONCLUSIONS: Upregulation of NGF, BDNF, USP36 and Nedd4-2 in SIP indicates dysregulation in the molecular events underlying the disease biology and could be exploited as potential markers for the disease diagnosis.

Comparative evaluation of Sapindus Mukorossi extract with 17% EDTA on smear layer removal in various parts of the tooth root.

OBJECTIVES: This study aimed to compare the effectiveness of an experimental root canal irrigant and 17% Ethylene-di-amine tetra acetic acid for removal of the smear layer in the coronal, middle and apical portions of the root canal. MATERIALS AND METHODS: Ninety human single rooted maxillary and mandibular teeth were selected for this study. The teeth were randomly divided into two experimental groups and one control group as follows: Group A (Ethanolic extract of Sapindus Mukorossi), Group B (17% EDTA), and Group C (Distilled water). The root canals of all three groups were prepared with stainless steel K-files by means of the standard step-back technique and irrigated with 5.25% sodium hypo chloride. The teeth were decoronated, following the irrigation and divided longitudinally into two-halves and visualized using scanning electron microscope (SEM) for the amount of smear layer present utilizing the three-point score system. The observations were noted both before and after the treatment. Nonparametric tests were applied for the comparison and p-value ⩽ 0.05 was considered as statistically significant. RESULTS: It was evident from that smear layer was completely removed in coronal portion of 27 out of 30 teeth in-group A. For middle and apical areas of group A, 24 and 19 teeth showed complete smear layer removal. In-group B it was found that there were 24, 21, and 3 teeth at coronal, middle and apical, areas respectively where smear layer were completely absent. Intra group comparison showed a significant difference (p = 0.002) in smear layer removal was found for group A at coronal, middle and apical thirds. Similarly, a significant difference (p = 0.001) was also found for group B; however heavy smear layer was found among the three parts of the canal for group C. CONCLUSIONS: Ethanolic extract of Sapindus Mukorossi have higher effectiveness in removing the smear layer from the root canal in comparison to 17% EDTA.

Comparison Of An Experimental Root Canal Irrigant (Sapindus Mukorossi) And Ethylenediaminetetraacetic Acid On Microhardness Of Human Dentin.

BACKGROUND: The treatment of infected root canals is one of the most essential areas in dentistry. The endodontic therapy comprises of a sequence of steps that includes the purging of disease and infectious tissues from the root canal system. The objective of the study is to compare the effect of an experimental herbal root canal irrigant (Sapindus mukorossi) and Ethylenediaminetetraacetic acid, on the micro hardness of human dentin. METHODS: Ninety single rooted teeth were collected displayed intact external morphology the selected teeth were than divided randomly into 3 groups (n=30); 1 control and 2 experimental groups: Group A consisted of specimen treated with Ethanolic extract of Sapindus mukorossi. Group B consisted of specimen treated with 17% Ethylenediaminetetraacetic acid and Group C (control group) consisted of specimen of roots were sectioned immersed in distilled water. After the removal of crowns, the roots were sectioned embedded in the polymer resin leaving the root dentine exposed, the micro hardness was determined. Then, the samples from each group were treated with respective irrigant solution for 15 minutes and then observation regarding the micro hardness were noted again by using Vickers micro hardness tester. Analysis of data were obtained by application of Wilcoxon signed rank test. RESULTS: The study revealed that there was no significant difference noted in dentin microhardness of group "A" sample after dipping in experimental irrigant solution (Sapindus mukorossi). However, the study found significant difference in context of decrease in dentin microhardness after dipping a sample in a group "B" irrigant solution (17% Ethylenediaminetetraacetic acid). CONCLUSIONS: In order to preserve the strength of dentin that will ultimately be beneficial for increase in survival of teeth in function, probably the herbal extract of Sapindus mukorossi would be better candidate for future endeavour and presented as an economic and effective alternative amongst root canal irrigants.

Effect of Erosive Agents on Surface Characteristics of Nano-Fluorapatite Ceramic: An In-Vitro Study.

Erosive beverages cause dissolution of natural teeth and intra-oral restorations, resulting in surface characteristic changes, particularly roughness and degradation. The purpose of this study was to evaluate the surface roughness and topography of a dental ceramic following immersion in locally available erosive solutions. A total of 160 disc specimens of a nano-fluorapatite type ceramic (12 mm diameter and 2 mm thickness) were fabricated and equally distributed into two groups (n = 80) and then evenly distributed among the following five testing groups (n = 16): lemon juice, citrate buffer solution, 4% acetic acid, soft cola drink, and distilled water which served as a control. The surface roughness (Ra) and topography were evaluated using a profilometer and scanning electron microscope at baseline, 24 h, 96 h, and 168 h respectively. Data were analyzed using ANOVA and Tukey's multiple comparisons (p ≤ 0.05). Surface changes were observed upon exposure to all acidic beverages except distilled water. Amongst all immersion media, 4% acetic acid produced the most severe surface roughness across all time periods (i.e., baseline, 24 h, 96 h, and 168 h). A statistically significant difference in the surface roughness values between all immersion media and across all four time intervals was observed. Erosive agents had a negative effect on the surface roughness and topography of the tested ceramic. The surface roughness increased with increased storage time intervals.

An In-Vitro Evaluation of Microleakage in Resin-Based Restorative Materials at Different Time Intervals.

A vital feature of conservative dentistry is the adhesion of the restorative material to the tooth structure for restoration of the tooth substance lost due to dental decay, trauma, or dental imperfections. In a perfect world, a restorative material should generate a lasting adhesion by bonding the restoration with tooth tissues. The ingress of micro-organisms, oral fluids, molecules, and ions through microscopic spaces due to faulty adhesion between restoration and tooth structure is known as microleakage. This study is focuses on the evaluation of adhesive failures between the restorative materials. In the past, studies have focused more on the bonding potential of a restorative material with the tooth surface. Therefore, there is need to carry out a study that compares the microleakage between resin-based restorative materials in a sandwich manner with and without the intermediate bonding layer after immersion in 2% methylene blue dye at different time intervals. The restorative materials used were composite Ceram X Mono plus (DENTSPLY) and Z350 (3M ESPE), Vitremer resin modified glass ionomer cement (RMGIC) (3M ESPE), smart dentine replacement SDR (3M ESPE), Bond NT (DENTSPLY), and Universal Bond (3M ESPE). A light emitting diode (LED) was used to cure the specimens. Artificial saliva was used as a storage medium for the specimens. Thermocycling of specimens was carried out at 500 cycles/30 s and 1000 cycles/30 s. The world health organization (WHO) grading tool for microleakage was used to analyze fluid ingress in the specimens through disclosing by 2% methylene blue dye. The statistical analysis was carried out with one-way analysis of variance (ANOVA) and Tukey post hoc test, keeping the level of significance at p ≤ 0.05. In Grade 0 = 85 samples, Grade 1 = 10 samples, Grade 2 = 7 samples, Grade 3 = 16 samples, and in Grade 4 = 2 samples were identified. This study describes that no microleakage was observed in SDR and resin composite groups as compared to Vitremer and resin composite groups.

Effect of pre-cooling agent on intensity of pricking pain at intraoral injection site in adults: An experimental study.

OBJECTIVE: To determine the effect of pre-cooling agent on the intensity of pricking pain at the intraoral injection site in adult patients. METHODS: The in-vivo interventional study was conducted at the Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, from September 2018 to August 2019, and comprised adult patients of either gender. The pricking pain perception during needle administration was assessed using split-mouth technique. Topical anaesthesia benzocaine gel was applied on the left side, which was treated as controls, for 1 min, while on the right side, which was treated as the experimental side, refrigerated cartridge was placed for 2 min. Infiltration anaesthesia was then administered on both sides. Pain perception ratings were measured through visual analogue scale. After profound anaesthesia was achieved, restorative treatment was performed under rubber dam isolation. Data was analysed using SPSS 24. RESULTS: Of the 152 subjects, 77(50.65%) were females and 75(49.34%) were males. The overall mean age was 35.97±8.669 years (range: 21-50 years). The effect of refrigerated cartridge was significant on the intensity of pricking pain at the intraoral injection site in patients aged 41-50 years, and in female patients aged 21-30 years (p<0.05), whereas its effect was non-significant in males aged 21-30 years and patients aged 31-40 years (p>0.05). CONCLUSIONS: Pre-cooling agent was found to be effective in decreasing pricking pain felt by patients.

Comparison of gingival biotype in smokeless tobacco users (Gutka and Paan) and non-tobacco users.

OBJECTIVE: To assess the gingival biotypes in smokeless tobacco (Gutka and Paan) users and compare it with non-tobacco users in Karachi sub-population using trans-gingival probing method (TRAN). METHODS: This in-vivo, cross sectional study was conducted in the department of Operative Dentistry from 20th February 2019 to 25th June 2019 Dow University of Health Sciences, Karachi after obtaining ethical approval from the Institutional review board of DUHS (Ref: IRB-1207/DUHS/Approval/2019/21). A total of 70 participants, 35 subjects currently using smokeless tobacco (Gutka and Paan) and 35 non-tobacco users from both genders were included in the study after taking informed consent. Gingival biotype was recorded using probe transparency method. Probing of the gingival sulcus was performed at the mid-buccal aspect of both maxillary incisors. Depending on the visibility of the underlying probe gingiva was categorized as thin or thick. RESULTS: Statistically significant differences in gingival biotype was observed of both groups (p=0.005). Males were recorded with a higher percentage of thick gingiva in both groups (81% in smokeless tobacco and 65% in non-tobacco) while in females thick gingiva was more prevalent in smokeless tobacco group (85.7%) whereas thin gingiva was noted in non-tobacco group (66.7%); although the results between genders was statistically insignificant. The comparison between different age groups, genders and both groups was statistically insignificant. CONCLUSIONS: Significant difference was observed between gingival biotype of smokeless tobacco and non-tobacco user groups. No statistically significant results were observed between genders and age groups.

Efficacy of Handpiece Mounted Continuous Irrigation System for the Removal of Residual Pulpal Debris During Root Canal Preparation.

OBJECTIVE: The removal of residual pulpal debris (RPD) from the root canal walls, especially in necrotic teeth is important for successful endodontic outcome. The aim of this study was to evaluate the RPD removal efficacy of handpiece mounted continuous irrigation with simultaneous root canal preparation from the apical third of root canals as compared to conventional syringe irrigation (SI). MATERIALS AND METHODS: Ninety extracted teeth were randomly divided into three groups: SI; handpiece mounted continuous irrigation (CI); and both syringe and continuous irrigation (CI+SI). After root canal preparation, roots were sectioned at 1 (a), 3 (b) and 5 (c) mm from apex and prepared for Hematoxylin-Eosin staining. Sections were microscopically examined for presence of RPD. STATISTICAL ANALYSIS: Intergroup difference in average percentage of RPD at different root levels was calculated by using analysis of variance test (ANOVA). Tuckey test was used for pairwise comparison. RESULTS: ANOVA showed significant difference between all three groups (p < 0.05). SI group showed a significantly higher percentage of RPD as compared with CI and CI+ SI groups at all root levels (p < 0.01). At root level a, CI showed a significantly higher percentage of RPD as compared with CI+SI (p < 0.01). CONCLUSION: Handpiece mounted CI during rotary instrumentation showed a significant reduction in RPD as compared with conventional syringe irrigation. This technique was found to be an effective method for an enhanced root canal debridement.

Effect of Different Host-Related Factors on Postoperative Endodontic Pain in Necrotic Teeth Dressed with Interappointment Intracanal Medicaments: A Multicomparison Study.

OBJECTIVES: The current study aimed to assess the impact of factors such as age, gender, and the tooth type on postoperative endodontic pain in necrotic teeth with symptomatic periapical periodontitis and radiolucency dressed randomly with either calcium hydroxide or propolis paste. MATERIALS AND METHODS: The standard chemomechanical root canal preparation of 80 teeth was performed by the primary investigator. The intracanal medicaments were inserted by the secondary operator. Patients self-recorded their postoperative endodontic pain intensity with the help of visual analog scale at 4, 12, 24 (day 2), 48 (day 3), and 72 (day 4) hours. During analysis, patients (68/80) were grouped according to gender, age, and the tooth type. STATISTICAL ANALYSIS: Mann-Whitney's U test was applied for mean pain score comparison between genders and between tooth type. Kruskal-Wallis' test was applied for mean pain score comparison between the age groups. RESULTS: No significant difference (p > 0.05) in pain scores was found between the age groups and between the tooth types. Males had significantly higher pain scores as compared with females at days 2 (p = 0.035), 3 (p = 0.023), and 4 (p = 0.020). CONCLUSION: The results suggested that there was no impact of age and tooth types on postoperative endodontic pain.

Erosive Potential of 1% Phytic Acid on Radicular Dentine at Different Time Intervals.

Objective: The objective of this in-vitro study was to compare the erosive potential and smear layer removal ability of 1% Phytic acid (IP6) and 17% Ethylenediaminetetaacetic acid (EDTA). Methods: Canal preparation of 225 single rooted extracted human teeth was performed with Protaper NiTi rotary instruments. Teeth were divided into three groups according to the final irrigation protocol. Group 1: Saline irrigation (n=75), Group 2: 17% EDTA (n=75), Group 3: 1% Phytic Acid (n=75). Roots were splitted and observed under Scanning Electron Microscope (SEM) for erosion and smear layer removal. Mean differences between the groups for smear layer removal and erosion were assessed using the Kruskal Wallis and Mann Whitney U test. (P≤0.05) Friedman and Willcoxon Signed Rank tests were used to make comparisons within the groups. Results: Group 3 was significantly less erosive than Group 2 at all root portions (P<0.001). With regards to smear layer removal, group 2 (EDTA) removed more smear layer compared to group 3 (Phytic acid) at all root portions (P<0.001). Both 17% EDTA and 1% IP6 removed significantly less smear layer in the apical root portion. Intra group comparisons revealed no significant differences at any root level. There was a time dependent increase in erosion and smear layer removal in Group 2, with severe erosion at 5 minutes time interval. In Group 3, however, there was moderate erosion and smear removal at 3 and 5 minutes interval. Conclusion: IP6 at the concentration of 1% and pH 3 was less erosive than 17% EDTA. It exhibited moderate smear layer removal ability.

Effect of Chinese Propolis as an Intracanal Medicament on Post-Operative Endodontic Pain: A Double-Blind Randomized Controlled Trial.

Propolis is a potent anti-microbial and natural anti-inflammatory by-product obtained from the beehive. Studies have demonstrated the superior biocompatibility and anti-microbial properties of propolis as compared to calcium hydroxide. However, its effect on postoperative endodontic pain is unknown. Therefore, this study aimed to investigate the impact of Chinese propolis paste as an intracanal medicament on postoperative endodontic pain intensities compared with calcium hydroxide (control) at different time intervals in necrotic teeth with periapical radiolucency. Eighty patients with single-rooted necrotic teeth with visible periapical radiolucency were recruited and randomly allocated to either the calcium hydroxide or propolis groups. After chemo-mechanical preparation and intracanal medicament insertion, patients were given the VAS (visual analogue scale) to record pain scores. Inter-group data were compared and analyzed using two-way repeated measure ANOVA (Bonferroni test). A p-value of < 0.025 was considered significant. In total, >78% of the patients experienced no or only mild post-operative pain in both the groups at all time intervals, without any significant difference in pain scores between the two groups (p > 0.025). An overall flare-up rate of 14.8% was found. The results suggest that either of these medicaments can be used as an inter-appointment medication for the prevention of postoperative pain in necrotic cases.

Audiovisual Distraction: A Pricking Pain Reduction Modality among Ladies Receiving Intraoral Injections.

OBJECTIVE: To determine the effect of audiovisual distraction (AVD) using virtual reality device (bobo VRZ4-VRBOX) on intensity of pricking pain at the intraoral injection site among different age groups in ladies. STUDY DESIGN: Experimental study. PLACE AND DURATION OF STUDY: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, during September 2018 to March 2019. METHODOLOGY: An in-vivo interventional study, using split-mouth technique was conducted in 50 lady patients of sample size of 50, to investigate pricking pain perception during needle insertion. Topical anesthesia (benzocaine gel) was applied on left side (control) for 1 minute without audiovisual distraction (AVD); whereas, on the experimental side (right), similar methodology was followed after topical anesthesia but with AVD via VR-Z4 video eyeglasses after the local anesthesia was administered. Patients' pain perception ratings were measured through visual analog scale (VAS). After profound anesthesia was achieved, restorative treatment was performed under rubber dam isolation. RESULTS: Audiovisual (AV) device was effective in decreasing the pricking pain sensed by the patients during infiltrate anesthesia; but the score remained within the same pain category. The effect of audiovisual distraction (AVD) using virtual reality device (VRZ4-VRBOX) was statistically insignificant on intensity of pricking pain at the intraoral injection site among different age groups in ladies. CONCLUSION: AV device is not dependent on age (21-50 years) in reducing the pricking pain. Pain is effectively reduced after the use of AV device, but this reduction is not statistically significant.

An In-VitroEvaluation of Microleakage at the Cervical Margin Between two Different Class II Restorative Techniques Using Dye Penetration Method.

OBJECTIVE: To evaluate the coronal microleakage of packable composite using conventional incremental and posterior bulk fill flowable composite using Smart Dentine Replacement Single Step technique in the cervical margins of class II cavities in dentine using the dye penetration method. STUDY DESIGN: In-vitroInterventional study. PLACE AND DURATION OF STUDY: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences (DIKIOHS), Karachi, from November 2012 to April 2013. METHODOLOGY: One hundred and twenty extracted teeth (molars and premolars) were collected and randomly divided into two experimental groups (n=60 each) and were stored in normal saline until used. Fractured samples were excluded. Standardized class II proximal box only cavities were prepared and restored with conventional methacrylate based composite using incremental technique (Group A, n=40) and low stress methacrylate resin based composite SDR using single step technique (Group B, n=40). Samples were sectioned horizontally below the cervical margins and specimen disks were prepared. The specimens were thermocycled and sealed with acid resistant varnish leaving a 1-mm interface around cervical margin and immersed in 2% methylene blue buffered solution for 24 hours. Leakage was scored 0 - 4 and measured in mm. It washed and sectioned to evaluate under stereomicroscope. RESULTS: Mean penetration was 2.4280 ±0.79 mm for Group Aand 1.015 ±0.45 mm for Group B (p < 0.001). Maximum dye penetration score for group Awas 4 and group B was 3. CONCLUSION: SDR technique in combination with total etch technique at the cervical margin of class II restorations improved the marginal seal, when were placed in dentine and thermocycled.

Micromechanical Intervention in Sandwich Restoration.

OBJECTIVE: To evaluate the sealing ability of two different types of Glass Ionomer Cements (GICs) used for sandwich restorations and assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. STUDY DESIGN: Experimental study. PLACE AND DURATION OF STUDY: Department of Operative, DIEKIOHS (DUHS) and NED University, Karachi, from February to June 2011. METHODOLOGY: Eighty cavities were prepared on the proximal surfaces of 40 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=20) and restored as follows: Group CIE - Conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 minutes and acid etched (E) along the cavity margins with 37% phosphoric acid for 15 seconds, washed for 30 seconds and dried; the adhesive system was applied and light cured for 10 seconds, completing the restoration with composite resin light cured for 40 seconds; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 37ºC for 24 hours, rinsed under running water for 15 minutes, bisected mesiodistally and dye penetration was measured following the ISO/TS 11405-2003 standard. Kruskal Wallis and post Hoc tests significant differences in the microleakage among all the four groups. RESULTS: There was a significant difference between the two groups of GICs (RMGIC and CI, p=0.001). There was no significant difference in between the two sub-groups that is between CIN and CIE (p=0.656), and between Groups RME and RMN (p=0.995). CONCLUSION: Phosphoric acid etching of GIC, prior to the placement of composite resin, does not improve the sealing ability of sandwich restorations. RMGIC was more effective in preventing dye penetration at the GIC-resin composite dentine interfaces than CI.

Effect of different tetra pack juices on microhardness of direct tooth colored-restorative materials.

PURPOSE: To examine the effect of apple and orange juices on the surface hardness of direct tooth-colored restorative materials. MATERIALS AND METHODS: The materials included resin-modified glass ionomer cement (Vitremer 3M™ ESPE™ Core buildup restorative) and composite resin (Filtek™ 3M™ ESPE™ Z350). A total of 45 disks of each restorative material were prepared. The disks were divided into groups of 15, which were immersed for 7 days in deionized water (G1/G4, control group), apple juice (G2/G5), or orange juice (G3/G6). The pH of the apple juice was approximately 4.8 and the pH of the orange juice was approximately 4.9. Surface hardness tests were performed before immersion and at various times following immersion. Statistical analysis included two-way ANOVA with repeated measurement and Tukey's test. RESULTS: Exposure to juices significantly reduced the hardness of both materials (p < 0.05), while deionized water did not affect the surface hardness of either material. The ionomer cement experienced a greater reduction than the composite resin (p = 0.000). There was no significant difference in the effect of apple and orange juices. CONCLUSION: Juice box-type fruit juices reduced the hardness of direct tooth-colored restorative materials. Material selection should be considered when planning restorations in patients who have experienced tooth surface loss. In terms of the materials evaluated in this study, the composite material provides greater durability under acidic conditions.

Effectiveness of commonly available surface protecting agents in maintaining microhardness of two cements.

OBJECTIVE: To estimate the microhardness of glass ionomer cement (vitrofil) and resin modified glass ionomer cement (vitremere) in the presence and absence of different surface protections. STUDY DESIGN: An in-vitro experimental study. PLACE AND DURATION OF STUDY: The Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and the Department of Material Sciences, NED University, Karachi, from August 2011 to January 2012. METHODOLOGY: Seventy-two discs of each material were made in polytetrafluoroethylene mold which was 10 mm in diameter and 2 mm in thickness. Four groups were made for each material containing 18 discs; G1/G5 (control group), G2/G6 (solid petroleum jelly), G3/G7 vernal (resin varnish), G4/G8 (nail varnish). After initial setting reaction surface protection was applied to discs. Once the surface protection was dried, discs were stored in deionized water at 37°C for 24 hours. After 24 hours, the discs were polished. Microhardness test were performed in digital microhardness tester. The results were statistically analyzed with the help of two-way ANOVA. RESULTS: For glass ionomer cement the only G4 (nail varnish) differed from the G1 (control group) [p < 0.05], No significant difference was seen with other surface protection agents. For resin modified glass ionomer cement, the G7 (resin varnish) and G8 (nail varnish) gave better result from the G5 (control group). CONCLUSION: Nail varnish and resin varnish showed better surface protection for GIC and RMGIC. The presence of toluene in nail varnish have harmful effects so should not be preferred if resin varnish is available.

Effect of different irradiation times on microhardness and depth of cure of a nanocomposite resin.

OBJECTIVE: To determine the microhardness and depth of cure of nanocomposite using different irradiation times on both upper and lower surfaces of composite material. STUDY DESIGN: In-vitro experimental study design. PLACE AND DURATION OF STUDY: Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and NED University of Engineering and Technology, Karachi, from March to May 2010. METHODOLOGY: Total 120 cylinder shaped specimens; 60 specimens for depth of cure test and 60 specimens for micro hardness test were fabricated using A3 shade of nanocomposite (Filtek Z350 XT, 3M ESPE). For each irradiation time four groups were made (Group 1 = 20s), (Group 2 = 30s), (Group 3 = 40s) and (Group 4 = 60s). For each group fifteen specimens were used. The resin was placed and polymerized into a cylindrical plastic mold. Depth of cure was measured by using micrometer. Micro Vickers hardness was measured on both top and bottom surfaces. SPSS-16.0 was used for statistical analysis. RESULTS: There was statistically significant difference in the depth of cure between all groups showing the highest value in group 4 (p < 0.001). For hardness on top surface, there was a statistically significant difference in between groups 1 and 2 (p=0.001), groups 1 and 3 (p < 0.001), groups 1 and 4 (p < 0.001). There was no statistically significant difference between groups 2 and 3, groups 2 and 4 and in between groups 3 and 4. For hardness on bottom surface, there was statistically significant difference in between all groups showing the highest value in group 4 (p < 0.001). CONCLUSION: Depth of cure and hardness was increased by increasing irradiation time. Hardness on the top surface was higher than bottom surface values.