in-vitro evaluation 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-vitro Interventional 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 A and 1.015 +/-0.45 mm for Group B [p < 0.001]. Maximum dye penetration score for group A was 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

In vitro comparative study of two different bleaching agents on micro-hardness dental enamel

Objective: To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide [CP] and in-office bleaching agent containing 38% Hydrogen Peroxide [HP] on enamel micro-hardness

Study Design: An in vitro experimental study

Place and Duration of Study: Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014

Methodology: A total of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens [n=30]. Group 1 was kept in artificial saliva at 37[degree]C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37[degree]C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester [Wolpert 402 MVD, Germany] was adjusted to a load of 0.1 kg [100 gm] and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14

Results: In the control group, the baseline micro-hardness was 181.1 +/- 9.3 which was reduced after the storage on day 1, 7 and 14 [p = 0.104]. In Group 2, baseline micro-hardness was 180.4 +/- 10.1 which was reduced to 179.79 +/- 10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 +/- 10 and 179.7 +/- 10.29, respectively [p=0.091]. Furthermore, the baseline micro-hardness in Group 3 was 174.0 +/- 22.9 units which was reduced to 173 +/- 23 on day 1, 170 +/- 30 on day 7 and 173 +/- 23 on day 14 [p = 0.256]. The statistically insignificant difference was found among micro-hardness values of different bleaching agents [p = 0.118]

Conclusion: Bleaching with 38% Hydrogen Peroxide [HP] and 16% Carbamide Peroxide [CP] resulted in insignificant effect on surface micro-hardness of enamel

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 37[degree]C 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

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

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. An in-vitro experimental 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. 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. 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]. 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 tetra pack juices on microhardness of direct tooth colored-restorative materials

To examine the effect of apple and orange juices on the surface h ardness of direct tooth-colored restorative materials. The materials included resin-modified glass ionomer cement [Vitremer 3M[tm] ESPE[tm] Core buildup restorative] and composite resin [Filtek[tm] 3M[tm] ESPE[tm] 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. 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. 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

Knowledge about the management of avulsed toothamong Karachi school teachers

The objective of this study was to assess the knowledge of school teachers regarding management of avulsed tooth. The information about the management of avulsed tooth was collected through a specifically designed questionnaire. A total of 150 questionnaires were distributed among teachers of five different private schools of Karachi who were dealing with children of 6 to 12 years old. Out of 150 teachers only 100 answered the questionnaire [66%]. Majority [80%] of the teachers knew about the importance of emergency management of tooth avulsions. One third [34%] teachers answered affirmative regarding their experience with tooth avulsions. 26% said that they would replant the avulsed tooth by themselves. More than half [57%] of the teachers, preferred water as the best storage medium than normal saline. Knowledge of school teachers regarding management of avulsed tooth was unsatisfactory. It should be improved by continuous dental educational seminars in schools

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

To determine the microhardness and depth of cure of nanocomposite using different irradiation times on both upper and lower surfaces of composite material. In-vitro experimental study design. 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. 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. 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]. Depth of cure and hardness was increased by increasing irradiation time. Hardness on the top surface was higher than bottom surface values

in vitro evaluation of apical microleakage of single cone obturation versus lateral condensation obturation technique

The aim of this in-vitro study was to use dye penetration method to compare the apical microleakage of matched taper single-cone and cold lateral condensation technique in teeth prepared with ProTaper instruments. Eighty [80] human extracted single rooted teeth were used. The teeth were randomly divided into two experimental groups of thirty [30] teeth each and two negative and positive control groups of ten [10] teeth each. The groups were as follows: Group I, Teeth were obturated using single cone obturation technique; Group II, Teeth were obturated using a cold lateral condensation technique. In positive control Group; teeth were instrumented and left unobturated, where as in negative control Group, teeth were instrumented and five [5] teeth were obturated with single cone obturation technique and five [5] teeth with the Lateral condensation technique. The access cavities of all teeth were obturated with Ketac Molar [3M ESPE] to ensure a coronal seal. The specimens were stored for 24 hours in 100% humidity at 37°C to allow the sealer to set. After that the surface of all roots in experimental and positive control groups were then covered with two layers of nail polish, except for the apical area [2mm]. In the negative control group all surfaces of the roots, including the apical area, were covered with two layers of nail polish. Each tooth was subsequently immersed in a freshly prepared 5% aqueous methylene blue dye solution [PH 7.0] at 37°C for seven days, and stored in incubator. Following storage, the roots were cut along their long axis and evaluated under a stereomicroscope to measure the depth of dye penetration. The negative controls showed no dye penetration while, the positive controls showed completely dye penetration. Mean and standard deviation of leakage for experimental groups were, for Single Cone Obturation, 6.42 [SD +/- 3.18], for Lateral Condensation Obturation, 6.44 [SD +/- 1.8]. There was no significant difference between the two groups [p=0.245]. Both the single cone and the lateral condensation obturation techniques proved equally effective in achieving the apical seal

To evaluate the effect of shef life on depth of cure of polyacid-modified composite - an in vitro study

The present study aimed to compare the curing depth of chemically similar Polyacid-modified composite resins [PAM-C] having different expiry periods. The curing depth of the PAM-C, Dyract Extra [Dentsply, U.K.] was determined for a near expiry and a long expiry material using a scraping method based on ISO 4049:2000. Samples were light-cured [800 mW/cm[2] at 40 seconds] in plastic mould. Immediately after light-curing the cylinder shaped material was removed from the mould, height of the cylinder of cured material was measured by using digital caliper and taken as the curing depth. The means of the curing depth of two materials were subjected to two sample independent t test using SPSS. The mean value of depth of cure for near expiry PAM-C [Group-A] was 6.389 mm [sd +/- .202] and that of long expiry material PAM-C [Group-B] was 7.087 mm [sd +/- .149]. The curing depth differed significantly between the materials of the two groups [P<0.001]. The curing depth greatly varies between the materials. It may be inferred that the curing depth of the two assigned groups of PAM-Cs depend on the period of expiry of the material

Incidence of three canals in mandibular second premolar: a case report

Mandibular second premolar often shows variant anatomy of having more the one canal. The reported incidence of three canals is quite rare. Successful treatment of this tooth requires the operator lobe familiar with its anatomical, clinical and radiographic variations. This article reports a case of unusual occurrence f three canals in the mandibular second Treatment recommendations for such cases are also discuss