Effect of liners on composite resin microleakage after selective carious lesion removal: an experimental study / Efecto de los recubrimiento en la microfiltración de resina compuesta después de la eliminación selectiva de lesiones cariosas: un estudio experimental

Objetive: To evaluate microleakage of composite resins (CR) placed over different cavitary liners after managing deep caries lesions through selective removal of soft carious tissue to soft dentin (SRCT-S). Material and Methods: Fifty four human teeth were collected for microleakage testing. Each assay comprised ICDAS 5 or ICDAS 6 carious lesions and sound teeth for controls. Sound teeth were prepared with cavities that mirrored the carious teeth cavities, which were prepared with SRCT-S. Sound and carious teeth were further randomly assigned to one of the three experimental groups: Group A: universal adhesive (UA) + CR, Group B: glass ionomer cement liner + UA + CR, and Group C: calcium hydroxide + UA+ CR. Occlusal microleakage (OM) and cervical microleakage (CM) was classified within one of 5 depth categories. ANOVA and Chi-square tests were computed (p<0.05). Results: OM and CM were similarly distributed across subgroups (p>0.05). All Group C samples with carious lesions presented some degree of microleakage. However, no statistically significant differences were observed between groups and within each group (p>0.05). Conclusion: Teeth restored with CR after SRCT-S using calcium hydroxide as a liner material seem to exhibit higher microleakage than those restored using glass ionomer or UA alone. Further clinical research is needed to deepen these findings. Clinical significance: The application of calcium hydroxide as a liner under a composite resin may reduce the longevity of a restoration after performing selective or partial removal of carious tissues. Clinicians should rethink the need of using calcium hydroxide for this application, albeit the lack of clinical evidence.

Objetivo: Evaluar la microfiltración de resinas compuestas (RC) colocadas sobre diferentes liners cavitarios después del manejo de lesiones de caries profundas mediante la remoción selectiva de tejido cariado blando hasta dentina blanda (SRCT-S). Material y Métodos: Se recolectaron 54 dientes humanos para pruebas de microfiltración. Cada ensayo comprendía lesiones cariosas ICDAS 5 o ICDAS 6 y dientes sanos para los controles. Se prepararon dientes sanos con cavidades que reflejaban las cavidades de los dientes cariados, que se prepararon con SRCT-S. Los dientes sanos y cariados se asignaron al azar a uno de los tres grupos experimentales: Grupo A: adhesivo universal (AU) + RC, Grupo B: revestimiento de cemento de ionómero de vidrio + AU + RC, y Grupo C: hidróxido de calcio + AU+ RC. La microfiltración oclusal (MO) y la microfiltración cervical (MC) se clasificaron dentro de una de las 5 categorías de profundidad. Se calcularon las pruebas ANOVA y Chi-cuadrado (p<0,05). Resultados: La MO y MC se distribuyeron de manera similar en los subgrupos (p> 0,05). Todas las muestras del Grupo C con lesiones cariosas presentaron algún grado de microfiltración. Sin embargo, no se observaron diferencias estadísticamente significativas entre grupos y dentro de cada grupo (p>0,05). Conclusión: Los dientes restaurados con RC después de SRCT-S usando hidróxido de calcio como material de revestimiento parecen exhibir una mayor microfiltración que aquellos restaurados usando ionómero de vidrio o AU solo. Se necesita más investigación clínica para profundizar estos hallazgos. Relevancia clínica: la aplicación de hidróxido de calcio como revestimiento debajo de una resina compuesta puede reducir la longevidad de una restauración después de realizar la eliminación selectiva o parcial de los tejidos cariados. Los médicos deberían reconsiderar la necesidad de usar hidróxido de calcio para esta aplicación, aunque no haya evidencia clínica.

Comparison of Retrograde, Primary and Secondary Bonding Materials with Tooth Substance.

OBJECTIVE: To compare the microleakage of MTA (mineral trioxide aggregate) and resin-modified GIC (glass ionomer vitremer) as retrograde endodontic material. STUDY DESIGN: Experimental study. PLACE AND DURATION OF STUDY: Operative Department of DIIKIOHS (DUHS) and NED University, Karachi, from February to June 2014. METHODOLOGY: Forty human anterior teeth were divided into four groups. Each tooth was endodontically treated. Apical cavity preparations were performed on all teeth. The retropreparations were filled either with MTA (Group 1), Vitremer (Group 2), or only covered with nail polish (Group 3). The root surfaces of the first three groups were coated with nail polish. In Group 4 (positive control), neither retrograde filling was placed nor the nail polish was applied. The teeth were then suspended in 2% methylene blue dye solution for 10 days at 37°C. Sections were made along the long axis of teeth to determine the depth of linear dye penetration. Using Mann-Whitney test the comparison, p-value <0.05 was considered as statistically significant. RESULTS: MTA had no significant difference in apical dye leakage (p = 0.122) than did the vitremer. CONCLUSION: MTA is equivalent to vitremer in preventing microleakage when used as retrograde filling material.

Effect of a novel quaternary ammonium silane cavity disinfectant on durability of resin-dentine bond.

OBJECTIVE: The present study examined the effect of a quaternary ammonium silane (QAS) cavity disinfectant on the viability of human dental pulp cells, dentine bond durability and nanoleakage of simplified etch-and-rinse adhesives. METHODS: Etched dentine surface of third molars were randomly divided into two adhesive groups, Adper™ Single Bond 2 and Prime & Bond® NT™. For each adhesive, the teeth were randomly assigned to five cavity disinfectant groups (N=6): Group 1: deionised water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS and Group 5: 10% QAS. The cavity disinfectants were applied on etched dentine surfaces for 20s, followed by adhesive application. The bonded teeth were sectioned for bond strength testing at 24h, 6 months and 12 months. Viability of human dental pulpal cells was examined using MTT assay. Bond strength data were analysed using 3-way ANOVA and Tukey test. Interfacial nanoleakage was evaluated after 24h and 12 months and analysed using Kruskal-Wallis test. RESULTS: Significant differences in bond strength were observed for the factors disinfectants (p<0.001) and time (p<0.001); while the factor, adhesive, was not significantly different (p=0.203). The 2% QAS cavity disinfectant preserved bond strength of both adhesives and reduced interfacial nanoleakage after 12 months. Cell viability was the lowest for 2% CHX, followed by 2% QAS and the control. CONCLUSIONS: The 2% QAS cavity disinfectant demonstrated greater cell viability compared to 2% CHX, with no adverse effect on immediate bond strength and preserved bond stability over time. CLINICAL SIGNIFICANCE: Incorporation of 2% quaternary ammonium silane cavity disinfectant in the resin-dentine bonding protocol enhances the success rate of bonded restorations.

Assessment of Coronal Leakage of Temporary Restorations in Root Canal-treated Teeth: An in vitro Study.

INTRODUCTION: Coronal leakage is one of the constant concerns in routine dental practice. It is one of the factors responsible for the failure of root canal therapy. Permanent restorations should be given as soon as possible after the completion of root canal therapy. If unavoidable, provisional restoration should be given in such a way that it maximally reduced the leakage of microorganisms and fluids from the external environment into the canal space. Hence, we evaluated the effect of saliva on the coronal leakage of temporary restorations. MATERIALS AND METHODS: Biomechanical preparation of the root canals of 204 fresh mandibular first premolar teeth was done using endodontic files with intermittent irrigation of sodium hypochlorite solution and ethylenediaminetetraacetic acid. Alternate irrigation with normal saline was done periodically. After preparation, drying of the canals was done using paper points followed by sealing of the apical foramen. For the assessment of the microleakage, Siqueira et al apparatus and method was used. All the specimens were divided into four groups based on the provisional restorative material used. All the groups were further divided into three subgroups based on the presence and absence of intracanal medicaments. Verissimo et al's criteria were used to check the turbidity at 1-, 2-, 3-, and 4-week interval respectively. All the results were analyzed by Statistical Package for the Social Sciences (SPSS) software. Chi-square test was used to measure the level of significance, and p < 0.05 was considered to be significant. RESULTS: In group I, all the subgroups' specimens showed significant difference at 1 week's time. Only the subgroup with no intracanal medicaments in Cavit-containing provisional restoration showed nonsignificant alterations. Statistically significant alterations were seen at 1, 2, and 3 weeks' interval in all the subgroups except for one with intracanal medicaments. CONCLUSION: All the temporary restorative materials were not able to prevent microleakage after 1 week's time, with worst bacterial resistance shown by Ketac Molar and ionomer restorative material. Future studies are advocated for better prognosis of root canal therapy.

Comparative evaluation of microleakage of a carbomer/fluoroapatite-enhanced glass-ionomer cement on primary teeth restorations.

AIM: Carbomer cement represents a novel glass-ionomer which gradually mineralises into fluoroapatite. Purpose of this study was to evaluate microleakage around restorations in deciduous teeth made with composite resin, conventional glass-ionomer cement, resin-modified glass-ionomer cement and carbomer/fluoroapatite-enhanced glass-ionomer cement. MATERIALS AND METHODS: A group of 40 primary upper canines, primary upper and lower molars was divided into 4 groups (n=10). Class I cavities were prepared by diamond cylindrical bur at high speed and were restored with a composite resin (Group 1), with a glass- ionomer cement (Group 2), with a resin-modified glass-ionomer cement (Group 3) and with a carbomer/fluoroapatite-enhanced glass- ionomer cement (Group 4). Hard tissue's bonding involved, in the case of composite resin a total etch bonding procedure, and in glass ionomers the use of their respective primers. Restorations were finished and polished. A 24-hour water storage was followed by thermocycling (1500 cycles, 5°C - 36°C - 55°C - 36°C with a dwell time of 15 seconds) and dye penetration test with immersion in 5% methylene blue for 24 hours. In order to assess the degree of microleakage longitudinal cuts were produced by means of a microtome at 0.5 mm and at 1 mm from the restoration margin, and photographs were taken with a stereomicroscope at 100X. Microleakage was classified according to the number of surfaces and the depth at which dye penetration was observed. Data were analysed with ANOVA and post-hoc analysis was performed with Bonferonni test (p<0.05). RESULTS: Statistical analysis exhibited no significant statistical difference between Group 2 and Group 3 (p>0.05). Statistical difference was exhibited between Group 3 and Group 4 (p<0.01), with Group 4 exhibiting lower microleakage values. Group 1 exhibited the lowest mean microleakage values and statistical difference in comparison with all groups (p<0.001). Group 4 exhibited the lowest microleakage values among the cements. CONCLUSION: Superior marginal integrity is achieved in restored primary teeth when composite resin is used. If the clinical case suggests the use of a glass-ionomer cement, carbomer/fluoroapatite-enhanced glass-ionomer cement is prefered in terms of microleakage.

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.

Effect of Scrubbing Technique with Mild Self-etching Adhesives on Dentin Bond Strengths and Nanoleakage Expression.

PURPOSE: To evaluate the effect of a scrubbing technique with one-step self-etching adhesives on bond strengths and nanoleakage expression at the resin/dentin interface. MATERIALS AND METHODS: Flat human dentin surfaces bonded with one of two mild self-etching adhesives, SE One (SE) or Scotchbond Universal (SU) applied either with scrubbing or without scrubbing technique, were prepared (n = 5). The microtensile bond strengths (µTBS), SE micrographs of morphological changes on treated dentin surfaces, and expression of nanoleakage along the bonded dentin interfaces as shown with TEM were evaluated. µTBS data were analyzed using two-way ANOVA and the post-hoc t-test at the significance level of 0.05. RESULTS: The scrubbing technique had a significant positive effect on the µTBS of SU (p < 0.05), while it produced no significant difference for SE (p > 0.05). Morphological evaluation of the treated dentin surfaces demonstrated that SU with scrubbing showed the highest etching ability, followed by scrubbing SE > nonscrubbing SE > nonscrubbing SU. In the nonscrubbing groups, nanoleakage formation using SU exhibited a reticular pattern throughout the hybridized complex, whereas with SE, water-tree nanoleakage was only found in the adhesive layer at dentinal tubule orifices. The scrubbing groups of both adhesives did not exhibit any nanoleakage expression. CONCLUSION: Using a scrubbing technique when applying mild self-etching adhesives could improve resin monomer infiltration into dentin, chase water on adhesive surfaces, and facilitate smear layer removal.

Evaluation of Microleakage of Nanoionomer and Nanocomposite Restorations, immersed in Fruit Drink, Fresh Fruit Juice and Soft Drink--An in vitro Study.

AIM: To evaluate microleakage of Nanoionomer (3M ESPE Ketac(™) N100 Light cured Nanoionomer Restorative) and Nanocomposite (3M ESPE Filtek(™) Z350 XT Universal Restorative) restorations, immersed in fruit drink, fresh fruit juice and soft drink. STUDY DESIGN: Eighty caries free maxillary premolars extracted for orthodontic purpose were used for the study. Class V cavities were prepared and restored with Nanocomposite on buccal surface and Nanoionomer on the palatal surface. The teeth were thermocycled following the restoration. The experimental groups comprised of 72 teeth (3 groups comprising 24 teeth each for fruit drink, fresh fruit juice and soft drink), while remaining 8 formed the control group. Each of experimental group was further divided into three subgroups (low, medium and high immersion). The teeth were finally immersed in Rhodamine B dye, sectioned and evaluated under stereomicroscope. Statistical analyses used were Mann-Whitney test and ANOVA test. RESULTS: The teeth showed statistically significant microleakage as the immersion regime increased. Soft drink group showed highest microleakage followed by fresh fruit juice and fruit drink. Nanocomposite exhibited more microleakage but the comparison was not statistically significant. CONCLUSION: The three beverages used in the study affected the microleakage of both restorative materials significantly. The microleakage scores increased as the frequency of the immersions increased. Soft drink caused highest microleakage followed by fresh fruit juice and fruit drink.

In Vitro Evaluation of Microleakage and Microhardness of Ethanolic Extracts of Propolis in Different Proportions Added to Glass Ionomer Cement.

OBJECTIVE: To evaluate the effect of ethanolic extracts of propolis (EEP) addition in different proportions to glass ionomer cement (GIC) on microleakage and microhardness of GIC. STUDY DESIGN: The cement was divided into four groups: one using the original composition and three with 10%, 25%, and 50% EEP added to the liquid and then manipulated. For microleakage assessment, sixty primary molars were randomly divided into four groups (n=15). Standard Class II cavities were prepared and then filled with EEP in different proportions added to GICs. Microleakage test was performed using a dye penetration method. The data were analyzed using one-way ANOVA and Mann-Whitney U tests (α = 0.05). Disc shaped specimens were prepared from the tested GIC to determine Vickers hardness (VHN). The data were analyzed using one-way ANOVA and post hoc Tukey test (α = 0.05). RESULTS: There were no statistically significant differences between the groups in terms of microleakage (p > 0.05). There were statistically significant differences between the VHN values of groups (p < 0.05). Increasing addition of EEP to GIC statistically significantly increased VHN value of GIC (p < 0.05). CONCLUSIONS: The addition of EEP to GIC increased the microhardness of the GIC and did not adversely affect the microleakage. Thus, it might be used during routine dental practice due to its antibacterial properties.

Evaluation of shear bond strength, penetration ability, microleakage and remineralisation capacity of glass ionomer-based fissure sealants.

AIM: The aim of this study was to evaluate the bond strength, penetration ability, microleakage, and remineralisation capacity of glass ionomer-based fissure sealant materials. MATERIALS AND METHODS: In this study, three glass ionomer-based fissure sealants were evaluated (Fuji Triage, Fuji VII EP, and GCP Glass Seal). A dye-penetration test was performed to evaluate microleakage under a stereomicroscope. The materials were applied to occlusal tooth surfaces, and bucco-lingual sections (1 mm width) were assessed to evaluate the penetration ability. Shear bond strength of tested materials was assessed using a universal testing machine. Finally, the remineralisation capacities of the materials were evaluated with EDS. RESULTS: The Fuji Triage exhibited the lowest microleakage and unfilled area proportion (p<0.05). The highest shear bond strength was calculated with Fuji VII EP (p<0.05). The fluoride content for all treatment groups was significantly different when remineralisation values were compared to demineralisation (p<0.05). CONCLUSION: Both the Fuji Triage and Fuji VII EP yielded compatible and satisfactory results and all fissure sealants used in this study are sufficient as anti-caries agents.

Effects of Dentin Moisture on Cementation of Fiber Posts to Root Canals.

PURPOSE: Achieving optimal moisture inside the root canal is a challenge during bonding of fiberglass posts. This study evaluated the effect of different moisture patterns on the push-out bond strength (PBS) and nanoleakage (NL) of fiber posts bonded to the root canal of two simplified etch-and-rinse adhesives. MATERIALS AND METHODS: The roots of 72 human premolars were endodontically prepared and divided into 6 groups according to the combination of the main factors: adhesive (Ambar and Adper Single Bond 2) and moisture (dry, wet, and overwet). The posts were cemented and after 1 week, the roots were cross sectioned into 6 disks. Two disks each were obtained from the cervical, middle, and apical thirds, and the PBS test was carried out (0.5 mm/min; n = 8). The NL was evaluated by scanning electron microscopy after the immersion of specimens in 50% silver nitrate (n = 4). The failure pattern was examined on all debonded specimens. Data were analyzed by three-way repeated measures ANOVA and Tukey's test (5%). RESULTS: For both adhesives, higher PBS values and lower NL were observed in the wet groups, and lower PBS and higher NL in the dry group. In general, the overwet condition showed intermediate results. CONCLUSIONS: The root dentin walls should be left slightly moist before performing fiber post cementation procedures.

Five-year Effects of Chlorhexidine on the In Vitro Durability of Resin/Dentin Interfaces.

PURPOSE: To evaluate the effect of an acid containing 2% chlorhexidine (Ac/CHX) or a 2% CHX aqueous solution (Aq/CHX) on the immediate and 5-year bonding properties of resin/dentin interfaces produced by two adhesives. The presence of CHX in these interfaces was also evaluated under micro-Raman spectroscopy. MATERIALS AND METHODS: Forty-two molars were ground to expose a flat dentin surface. In the control group, the surfaces were etched with conventional phosphoric acid, and Prime&Bond NT (PB) and Adper Single Bond 2 (SB) were applied. In Ac/CHX, an acid containing 2% CHX was applied after adhesive application. In the Aq/CHX group, an aqueous solution of 2% CHX was applied for 60 s after etching. After placing the restoration, specimens were prepared and tested using the microtensile bond strength test (µTBS, 0.5 mm/min) immediately or after 5 years. For nanoleakage (NL), specimens at each period were immersed in silver nitrate solution and examined by EDX-SEM. In addition, specimens at each period underwent examination for CHX using micro-Raman spectroscopy. Data were submitted to appropriate statistical analysis (a=0.05). RESULTS: After 5 years, NL was more pronounced in the control than in the Ac/CHX or Aq/CHX (p<0.001). Significant reductions in the µTBS were observed for all groups; however, they were more pronounced for the control (p<0.001). CHX was still present in the hybrid layers Ac/CHX or Aq/CHX groups after 5 years. CONCLUSION: The use of a 2% chlorhexidine-containing acid or the application of an aqueous CHX primer may increase the long-term stability of resin/dentin interfaces.

Influence of Cavity Margin Design and Restorative Material on Marginal Quality and Seal of Extended Class II Resin Composite Restorations In Vitro.

PURPOSE: To investigate the influence of three cavity designs on the marginal seal of large Class II cavities restored with low-shrinkage resin composite limited to the enamel. MATERIALS AND METHODS: One hundred twenty (120) intact human molars were randomly divided into 12 groups, with three different cavity designs: 1. undermined enamel, 2. box-shaped, and 3. proximal bevel. The teeth were restored with 1. an extra-low shrinkage (ELS) composite free of diluent monomers, 2. microhybrid composite (Herculite XRV), 3. nanohybrid composite (Filtek Supreme XTE), and 4. silorane-based composite (Filtek Silorane). After artificial aging by thermocycling and storage in physiological saline, epoxy resin replicas were prepared. To determine the integrity of the restorations' approximal margins, two methods were sequentially employed: 1. replicas were made of the 120 specimens and examined using SEM, and 2. the same 120 specimens were immersed in AgNO3 solution, and the dye penetration depth was observed with a light microscope. Statistical analysis was performed using the Kruskal-Wallis and the Dunn-Bonferroni tests. RESULTS: After bevel preparation, SEM observations showed that restorations did not exhibit a higher percentage of continuous margin (SEM-analysis; p>0.05), but more leakage was found than with the other cavity designs (p<0.05). The lowest percentage of continuous margin was observed in ELS restorations (p<0.05). More fractured margins were observed in the undermined enamel cavity design groups (p<0.05). CONCLUSION: Bevel preparation failed to improve margin quality in large Class II composite restorations and is no longer recommended. However, undermined enamel should be removed to prevent enamel fractures.

Micro-CT evaluation of microleakage under orthodontic ceramic brackets bonded with different bonding techniques and adhesives.

AIM: The aim of this study was to evaluate microleakage under orthodontic ceramic brackets bonded with direct and different indirect bonding techniques and adhesives using micro-computed tomography. MATERIALS AND METHODS: A total of 30 human maxillary premolars were randomly separated into five groups with six teeth in each group. In group I, teeth were bonded directly with Transbond XT (3M Unitek). In group II, group III, group IV, and group V, teeth were bonded through an indirect technique with Custom I.Q. (Reliance Orthodontic Products), Sondhi Rapid-Set (3M Unitek), RMbond (RMO), and Transbond IDB (3M Unitek), respectively, following the manufacturer's instructions. Micro-CT system model 1172 of Skyscan (Kontich, Belgium) was used to scan all samples. NRecon (Skyscan) version 1.6, CT-Analyser V.1.11 (Skyscan), and TView (SkyScan, Bvba) software programs were used for microleakage evaluation. Microleakage values between the test groups were assessed using the Kruskal-Wallis test, while the Wilcoxon signed rank test was used for within-group comparisons. The level of significance was set at P < 0.05. RESULTS: According to the Kruskal-Wallis analysis of variance test, there were no significant differences among the tested groups, with regard to volume and percentage (microleakage/region of interest × 100) of microleakage values (P < 0.05). The Wilcoxon signed rank test showed that coronal microleakage volume and percentage values significantly differed for RMbond and Transbond IDB groups. LIMITATIONS: In the study, only ceramic brackets were used and microleakage into mini gaps did not show up on the micro-CT image because 50% silver nitrate solution could not penetrate into mini gaps which are smaller than silver nitrate particles. CONCLUSION: Use of direct and indirect bonding techniques with different adhesives did not significantly affect the amount of microleakage.

Evaluation of a novel repetitive gas-enhanced permeation test for restoration leakage determination after thermo-mechanical loading.

OBJECTIVES: To assess leakage of class-I restorations using a gas-enhanced permeation test (GEPT) as compared with conventional SEM or dye analysis. MATERIALS AND METHODS: Pressure differences over time and penetrating water volumes were measured simultaneously in a two-chamber system (GEPT) before and after class I cavity preparation in 30 molars. Ten teeth were restored with a composite restoration without bonding (A1), a composite restoration with bonding (A2) or a ceramic indirect restoration (B). Five intact teeth served as controls (C). Another GEPT measurement was performed and impressions were taken. Teeth were subjected to thermodynamic loading (1 200 000 cycles) and final GEPT measurements and impressions were made. SEM evaluation of the marginal continuity was performed and teeth were subjected to a Fuchsin dye penetration test. Spearman's rank test was used to compare results from different tests. RESULTS: The GEPT and SEM values did not correlate before loading (0.359, p = 0.051), but significantly correlated afterwards (0.662, p < 0.0001). The correlations between the Fuchsin dye penetration test and GEPT and SEM surface marginal analysis were significant (0.777 and 0.534, p-values < 0.0001 and 0.002, respectively). CONCLUSIONS: SEM marginal analysis was mainly limited in reflecting the surface restoration integrity. GEPT evaluation may, therefore, serve as a tool to non-destructively assess restoration sub-surface integrity over time. CLINICAL RELEVANCE: The current study provided proof that restoration margin quality does not necessarily reflect its leakage behaviour.

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.

Sealing Ability of Four Calcium Containing Cements used for Repairing Furcal Perforations in Primary Molars: An in vitro study.

AIM: The aim of this study was to compare the sealing ability of mineral trioxide aggregate (MTA), Portland cement (PC), Biodentine(TM) and Tech biosealer in repairing furcal perforations in primary molars using the fluid-filtration technique. MATERIALS AND METHODS: Fifty freshly extracted maxillary second primary molars were sectioned horizontally at the furcation region to create dentin disks of 1.5 mm (+ 0.1 mm) thickness. Five disks were not perforated and served as negative controls. In the remaining 45 disks, furcation perforations were prepared. Five disks did not receive furcation repair and served as positive controls. The remaining 40 disks were then randomly divided into four equal groups (10 disks in each group). Perforations were repaired with: MTA, PC, Biodentine(TM) or Tech Biosealer. The sealing ability of the tested materials was evaluated by measuring microleakage for each disk after four different storage periods: 24-hour, 1-month, 6-month and 1-year storage using fluid-filtration. Comparisons between the four materials and the four time periods were done using the two-way analysis of variance and the Scheffe multiple comparisons test. RESULTS: There was no significant difference between the mean microleakage values obtained in the four tested materials after 24 hours, 1, 6 month and 1 year. However, microleakage values for each individual material were significantly higher at 24 hours than at the other time intervals. CONCLUSION: Mineral trioxide aggregate, PC, Biodentine(TM) and Tech biosealer showed similar capabilities in sealing the furcal perforations of the primary molars, where the sealing ability improved over time for each individual material.

Evaluation of Solubility and Microleakage of Glass Carbomer Sealant.

AIM: This study was carried out to evaluate and compare solubility and microleakage of the newly introduced moisture tolerant glass carbomer sealant. STUDY DESIGN: For evaluation of solubility, 20 specimens of glass carbomer and conventional glass ionomer were prepared and immersed in artificial saliva of pH 4 and 6 for seven days. The difference between initial and final weight was calculated. For evaluation of microleakage, glass carbomer was compared with a conventional resin sealant. 20 premolar teeth indicated for orthodontic extraction were collected and divided into two groups and the respective sealants were applied. It was subjected to thermocycling and then kept immersed in methylene blue for 24 hours. Dye penetration was scored. RESULTS: The glass carbomer specimens were less soluble than the conventional glass ionomer at both pH values. There was no significant difference in the microleakage. CONCLUSION: Being moisture resistant, glass carbomer can be used as an alternative fissure sealant material; especially in young children with partially erupted teeth and where obtaining moisture control is difficult.

Alternative Aging Solutions to Accelerate Resin-Dentin Bond Degradation.

PURPOSE: This study evaluated the effect of aging solutions on the durability of resin-dentin bonds by means of microtensile bond strength (µTBS) and nanoleakage (NL) tests. MATERIALS AND METHODS: The adhesive system Adper Single Bond 2 (3M ESPE) was applied according to the manufacturer's instructions to the flattened occlusal surface of 40 extracted human molars. After bonding, teeth were sectioned to obtain bonded sticks (0.8 mm2 area) which were tested in tension immediately or after different storage periods (1 week, 1 month, or 6 months). Bonded sticks were kept immersed in 5 different solutions: 1) distilled water (DW); 2) 99.9% propionic acid (PA); 3) 99% acetic acid (AA); 4) 75% ethanol (ET), and 5) mineral oil (MO). To determine NL, bonded sticks from each experimental condition were immersed in silver nitrate and analyzed by SEM. Data were analyzed by two-way repeated measure ANOVA and Tukey's test (α=0.05). RESULTS: Faster degradation of bond strength (1 week) could be seen for AA and ET (p<0.05) in comparison with DW. Specimens stored in PA and DW showed bond strengths significantly reduced after one and six months, respectively (p<0.05). No degradation of the resin-dentin bond strengths was observed for specimens stored in MO (p>0.05). Nanoleakage increased for all groups except MO after storage. CONCLUSION: Propionic acid, acetic acid, and ethanol can be used as alternative aging solutions to more quickly obtain results on the bond resistance to degradation.

Evaluation of the influence of three different temperatures on microleakage of two self-etch and one total-etch adhesives.

AIM: To evaluate the bonding temperature effect on dentin-restoration microleakage. The null hypothesis of the study is that the score of microleakage is identical among different adhesive bondings at different temperatures. MATERIALS AND METHODS: Ninety caries free maxillary premolars were selected. Class V cavities were prepared on the cemento enamel junction (CEJ) of the buccal sides with enamel margins on occlusal sides and cementum margins on gingival sides. The specimens were divided into 3 groups: G1, single bond adhesive + Z250 composite; G2, P90 adhesive + Filtek Silorane composite; and G3, Clearfil SE bond + Clearfil APX. All groups were divided into three subgroups based on the adhesive temperature: A-4°C; B-25°C; and C-40°C. After coating the specimens with nail polish 1 mm beyond the margin of the restorations, they were stored in 0.5% basic Fuchsin dye solution for 24 hours. The teeth then were buccolingually sectioned and observed under a stereomicroscope. RESULTS: There was no significant difference between microleakage of occlusal and gingival margins in each group. Clearfil SE bond and Adper single bond displayed lower microleakage than P90 adhesive at 4°C and 25°C. The most and least microleakage score for Adper single bond was at 40°C and 25°C respectively. Clearfil SE bond showed less microleakage at 25°C than 4°C and 40°C. CONCLUSION: Clearfil SE bond and Adper single bond displayed less microleakage at 25°C while there was no significant difference among for P90 adhesive microleakage at three temperatures.