Significant Difference In Microleakage Research Articles

In vitrostudy of microleakage of endodontically treated teeth restored with different adhesive systems and fiber-reinforced posts

Purpose: While studies have examined microleakage in endodontically treated teeth restored with posts, microleakage among post and adhesive systems remains a concern. This study compared the sealing properties of 3 adhesively luted post systems. Materials and methods: Thirty-six endodontically treated permanent maxillary central incisors were divided into 3 groups: Zirconia-glass fiber, Quartz-glass fiber, Polyethylene fiber posts. Post space was prepared and each post was adhesively luted with 3 systems. The specimens were separately immersed in freshly prepared 2% methylene blue solution for 1 week. The cleaned specimens were then embedded in autopolymerizing acrylic resin. The root portion of tooth were horizontally sectioned into three pieces (apical, middle, and coronal portions). An occlusal view of each section was digitally photographed with a stereomicroscope. The methylene blue-infiltrated surface for each specimen was measured. Dye penetration was estimated as the ratio of the methylene blue-infiltrated surface to the total dentin surface. Results: No significant differences were found among post types. The variables of middle section and 3-stage adhesive produced significant differences in microleakage between the following post pairs: zirconia-glass fiber versus quartz-glass fiber, zirconia-glass fiber versus polyethylene fiber, and quartz-glass fiber versus polyethylene fiber (P<.05). There were significant differences between the apical and coronal sections of each post type, and between apical versus middle sections of quarze-glass fiber and polyethylene fiber posts (P<.05). Conclusion: No significant differences were found among post types. The 3-stage adhesive produced significant differences in microleakage between the following post pairs. (J Korean Acad Prosthodont 2014;52:74-81)

Comparative Evaluation of Microleakage in Conventional and RMGIC Restorations following Conventional and Chemomechanical Caries Removal: An in vitro Study.

ABSTRACT%Background: Conventional caries removal involves use of high-speed handpiece. Current concepts of caries excavation in cavitated lesions consist of manual excavators. Principles of minimal invasive approach indicate the need to excavate only carious tissue.Aim: The aim of this study was to compare the microleakage in conventional and resin modified glass ionomer cement restorations following conventional and chemomechanical caries removal.Design: Hundred class I carious human mandibular first molar s were collected and divided into two groups: I and II (50 each). Each group was further divided into subgroups, i.e. (IA, IB and IIA, IIB). Caries was completely removed using conventional method in group one and chemomechanically in group two. The teeth in group IA, IIA are restored with conventional glass ionomer comment (GIC) and in group IB, IIB restored with resign-modified glass ionomer comments (RMGIC), followed by fnishing and polishing. Subsequently, the specimens were thermocycled and then placed in dye solution. The teeth were sectioned through the restorations and evaluated for microleakage scores using a stereomicroscope. The data were analyzed using Mann-Whitney U-test.Results: Statistical analysis showed no significant difference in microleakage between the conventional GIC and RMGIC following conventional and chemomechanical caries removal method.Conclusion: Carisolv is minimally invasive and an effective alternative treatment for the removal of occlusal caries.How to cite this article: Pavuluri C, Nuvvula S, Kamatham RL, Nirmala SVSG. Comparative Evaluation of Microleakage in Conventional and RMGIC Restorations following Conventional and Chemomechanical Caries Removal: An in vitro Study. Int J Clin Pediatr Dent 2014;7(3):172-175.

Microleakage evaluation of adhesive systems following pulp chamber irrigation with sodium hypochlorite.

Background and aims. This in vitro study evaluated the effect of delaying composite resin restorative procedures bonded with total-etch and self-etch adhesive systems on microleakage following root canal irrigation with sodium hy-pochlorite (NaOCl) solution. Materials and methods. The roofs of pulp chambers and roots (1–2 mm below furcation) of 40 human first molar teeth were cut and pulp tissues completely removed. The teeth were randomly divided into two main groups (n = 20). Group E (experimental) was irrigated with 5% NaOCl and group C (control) was left untreated. For the experimental group, after obturation of root canals with gutta-percha and sealing the cavity with Cavit, the specimens were stored in artificialsaliva for two weeks. Then each group was divided into two subgroups according to the total-etch or self-etch adhesive application protocol: Scotchbond Multi-Purpose and Clearfil SE Bond. The specimens were restored with composite resin using each bonding agent: Z250 and Clearfil Photo Core, respectively. Fluid filtration method was used for evaluation of microleakage. Data was analyzed using two-way ANOVA ( α= 0.05). Results. Two types of dentin adhesive systems showed no statistically significant differences in microleakage (P = 0.77). NaOCl-treated groups demonstrated significantly higher microleakage values compared to the non-NaOCl-treated groups (P= 0.001). The interaction between the two factors was not significant (P = 0.78). Conclusion. Differences in inlay temperature had no effect on microleakage. CAD/CAM inlays had lower cement thick-ness than laboratory-made inlays, but this was not related to their microleakage.

Effect of operator variability on microleakage with different adhesive systems.

Objective:The objective of this study was to evaluate the effect of operator variability on microleakage with different adhesive systems.Materials and Methods:A total of 180 standardized Class V cavities were prepared on facial and lingual of 90 extracted human premolar teeth and randomly assigned to five groups according to the adhesive systems used (n = 36): Prime and Bond NT (PB), Single Bond (SB), Futura Bond NR, Xeno III (XE) and Adper Prompt-L-Pop (LP). The adhesive groups were then further subdivided into three operator groups according to level of clinical experience (n = 12): An undergraduate student, a research assistant and a faculty member. All cavities were restored with same composite resin. The restored teeth were thermocycled (500 cycles, 5-55°C) then immersed in 0.5% basic fuchsin and measured for leakage under a stereomicroscope. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney U tests.Results:Significant inter-operator variation was found in the enamel margins in the XE group with significantly higher microleakage when used by the undergraduate student (P < 0.05). Although no significant differences in microleakage were found between adhesive systems for the research assistant and faculty member (P > 0.05), significant differences were observed between PB and LP, PB and XE, SB and LP and SB and XE in the enamel margins for the undergraduate student (P < 0.05).Conclusion:Microleakage of adhesive systems is more dependent on interactions between the operator and adhesive material than on the choice of adhesive material.

The influence of different light-curing modes on microleakage of posterior resin composites

This investigation evaluated the effect of various curing modes on the extent of microleakage of differently resin-based posterior composites. Box-form Class II (MO/OD) cavities (n = 8) were prepared on proximal sides of 36 human sound mandibular molars. The cavities were restored by posterior composites (Filtek™ P90, Filtek™ Z250, and Filtek™ P60). The composite was placed in horizontal layers and irradiated occlusally by Astralis™ 10 light source at three modes of continuous intensities (conventional, high intensity power, and pulse-soft start). The specimens were thermocycled for 500 cycles at 5–55 °C, then immersed in 2% methylene blue solution for 4-h at 37 °C. The microleakage was examined by a stereomicroscope and scored occlusally and gingivally according to the ordinal scoring criteria. The Kruskal–Wallis revealed high significant differences between microleakage medians of the posterior composites examined (p < 0.05). However, no significant differences were noted between microleakage medians at different modes of curing intensities occlusally (p = 0.076) and there were significant differences gingivally (p = 0.015). Mann–Whitney U-test showed a significant difference in microleakage for cavities restored by Z250 between high power and pulse modes of cure (p = 0.006). The highest microleakage score was identified in the cavities restored with P60, while the lowest microleakage score was found in cavities restored by P90 specifically at conventional and pulse mode of cure. The light intensity modes have no significant effect on the microleakage, while the difference in composition of posterior resin composites investigated was the main factor for such a significant difference.

The effect of 3 T MRI on microleakage of amalgam restorations

To evaluate the effects of 3 T magnetic field on microleakage of amalgam restorations containing three different types of silver (Ag). 60 extracted teeth were restored with three different types of amalgam filling materials. Restored teeth were sectioned mesiodistally and divided into experimental and control groups. Experimental groups were exposed to a magnetic field of 3 T for 20 min. All samples were plunged into 2% basic fuchsin solution and examined under a digital microscope by three different observers with regard to microleakage. Statistical analysis showed significant differences in microleakage between the groups exposed to MRI and controls, whereas differences in microleakage between amalgam types were insignificant. The primary risk of MRI systems arises from the effects of its strong magnetic field on objects containing ferromagnetic materials. An MRI of 1.5 T is known to be safe for amalgam restorations. However, our research indicates that MRI is not completely devoid of any effects on amalgam restorations.

Comparison of the Effect of Nd:YAG and Diode Lasers and Photodynamic Therapy on Microleakage of Class V Composite Resin Restorations.

Background and aims Considering the importance of disinfecting dentin after cavity preparation and the possible effect of disinfection methods on induction of various reactions between the tooth structure and the adhesive restorative material, the aim of the present study was to evaluate microleakage of composite resin restorations after disinfecting the prepared dentin surface with Nd:YAG and Diode lasers and photodynamic therapy. Materials and methodsStandard Class V cavities were prepared on buccal surfaces of 96 sound bovine teeth. The samples were randomly divided into 4 groups based on the disinfection method: Group 1: Nd:YAG laser; Group 2: Diode laser; Group 3: photodynamic therapy; and Group 4: the control. Self-etch bonding agent (Clearfil SE Bond) was applied and all the cavities were restored with composite resin (Z100). After thermocycling and immersing in 0.5% basic fuchsin, the samples were prepared for microleakage evaluation under a stereomicroscope. Data was analyzed with Kruskal-Wallis and Wilcoxon signed-rank tests at P<0.05. ResultsThere were no significant differences in the microleakage of occlusal and gingival margins between the study groups (P>0.05). There were no significant differences in microleakage between the occlusal and gingival margins in the Nd:YAG laser group (P>0.05). In the other groups, microleakage at gingival margins was significantly higher than that at the occlusal margins (P<0.05). ConclusionNd:YAG and Diode lasers and photodynamic therapy can be used to disinfect cavity preparations before composite resin restorations.

Microleakage evaluation of Silorane-based composite and Methacrylate-based composite in class II box preparations using two different layering techniques: An in vitro study

The aim of this study was to compare the microleakage in Class II box preparations with the gingival margin above and below the cemento-enamel junction (CEJ) restored with Silorane composite and methacrylate composite using two different layering techniques. Standardized box preparations (mesial box 1 mm above the CEJ and distal box 1 mm below the CEJ) were prepared in 60 upper premolars. The teeth were randomly divided into four groups containing 15 samples each; Group I: Restored with a Silorane composite using an oblique layering technique, Group II: Restored with Silorane composite using a vertical layering technique, Group III: Restored with methacrylate composite using the oblique layering technique, and Group IV: Restored with methacrylate composite using the vertical layering technique. The samples were stored in distilled water, followed by thermocycling and immersed in 2% methylene blue. The samples were sectioned and evaluated for microleakage at the gingival margin. Kruskal-Wallis, Fischer exact test, Wilicoxon test, and Mann-Whitney U test. Silorane composite had significantly lesser microleakage. No significant difference in microleakage was observed above and below the CEJ for Silorane-based composite. Silorane composite resin showed lesser microleakage compared to methacrylate composite resin. The Silorane-based composites improve the marginal adaptation due to their reduced shrinkage, thereby decreasing the residual stress at the adhesive-tooth interface.

Effect of Home Bleaching on Microleakage of Fiber-reinforced and Particle-filled Composite Resins.

Background and aims. Bleaching may exert some negative effects on existing composite resin restorations. The aim of this study was to evaluate the effect of home bleaching on microleakage of fiber-reinforced and particle-filled composite resins. Materials and methods. Ninety class V cavities (1.5×2×3 mm) were prepared on the buccal surfaces of 90 bovine teeth. The teeth were randomly divided into 6 groups (n=15) and restored as follows: Groups 1 and 2 with Z100, groups 3 and 4 with Z250, and groups 5 and 6 with Nulite F composite resins. All the specimens were thermocycled. Groups 1, 3 and 5 were selected as control groups (without bleaching) and the experimental groups 2, 4 and 6 were bleached with 22% carbamide peroxide gel. All the samples were immersed in 2% basic fuchsin dye for 24 hours and then sectioned longitudinally. Dye penetration was evaluated under a stereomicroscope (×25), at both the gingival and incisal margins. Data were analyzed using Kruskal-Wallis, Mann-Whitney and Wilcoxon tests (a=0.05). Results. Statistical analyses revealed that bleaching gel increased microleakage only at gingival margins with Z250 (P=0.007). Moreover, the control groups showed a statistically significant difference in microleakage at their gingival margins. Nulite F had the maximum microleakage while Z250 showed the minimum (P=0.006). Conclusion. Microleakage of home-bleached restorations might be related to the type of composite resin used.

Use of fluid filtration method to evaluate the effect of master cone size on the apical seal of severely curved root canals

The apical third of most root canals shows some degree of curvature, which is important in cleaning/shaping and obturation during root canal treatment. The present study evaluated the effect of master cone size on the apical seal of severely curved root canals. Thirty-eight mesial roots of human mandibular first molars were prepared using the crown-down technique. All samples were mature roots with closed apices, had no carious lesions or resorption, and had a canal curvature of > 45º to 60º. Two samples were used as a negative and positive control to evaluate the fluid filtration equipment, and the remaining 36 samples were equally divided into groups A, B, and C based on master cone size, namely, gutta-percha #20, #25, and #30, respectively. The fluid filtration method was used to evaluate microleakage. No significant difference in microleakage was observed among groups (P = 0.31). In conclusion, an increase in master cone size up to #30 does not significantly influence apical microleakage.

Evaluation of Microleakage of Soft Liners to Highly Impact Acrylic Resin

Aims: To evaluat the microleakage of four types of soft Liners materials(Vertex, Molloplast B, Bony plus and Silicon promedica) with different surface treatment: acetone, monomer, and laser at different period of storage to highly impact acrylic resin. Materials and Methods: Two hundred and forty spe-cimens for microleakage have been prepared , each specimens consists of two parts: acrylic resin den-ture base part (30mm) diameter , ( 2mm) thickness of acrylic resin and (30mm) diameter, (2mm) thik-ness of soft liners. Soft denture liners bonded to three different groups of surface treatment: acetone, monomer, laser treated to denture base resin. Microleakage specimens underwent three aging proce-dures: storage at one week, one month without thermocyling and one month with thermocyling inside 2% methylen blue dye in 600 cycles. Results: The results showed that microleakage of Vertex and Molloplast_B in one week and in one month without thermocyling were the lowest value from the oth-er types , in one month with thermocyling the vertex was the lowest of microleakage than oth-ers.Treating the surface of denture bases with acetone and monomer had the highest value of microlea-kage from other types of surface treatment in one week ,while in one month without thermocyling and one month with thermocycle, there were no significant difference in microleakage among the the dif-ferent types of surface treatment of acrylic resin Conclusions: Permanent soft liner of acrylic type (ver-tex) had the lowest values of microleakage after different periods of storage and thermocyling .

Microleakage of Class V compomer resin restorations after conventional diamond bur and Er, Cr:YSGG laser preparation

Objectives: The aim of this study was to compared the microleakage of Class V compomer resin restorations prepared by Er,Cr:YSGG laser or conventional diamond bur. Materials and Methods: Ninety sound primary molar teeth were randomly assigned to the six study groups, pretreated as follows: Group1:2W-10Hz Er,Cr:YSGG laser irradiation; Group2:2W-20Hz Er,Cr:YSGG laser irradiation; Group3:2,5W-10Hz Er,Cr:YSGG laser irradiation; Group4:2,5W-20Hz Er,Cr:YSGG laser irradiation; Group5: 3W-10Hz Er,Cr:YSGG laser irradiation; and Group6:3W laser-20Hz Er,Cr:YSGG laser irradiation. Each tooth hosted one test cavity prepared with one of the Er,Cr:YSGG laser irradiation and one control cavity prepared with a conventional diamond bur in a high-speed hand piece. Both cavities were placed at the cervical margin of the tooth and were restored and finished according to the manufacturer’s instructions. All the restorations were subjected to thermocycling and load cycling. Microleakage was assessed using 0.5% basic-fuchsin solution and the specimens were sectioned longitudinally in buccolingual direction. Dye penetration was scored based upon the extent of the dye using a stereo-microscope. The data were analyzed using the Kruskal-Wallis and Wilcoxon Signed Ranks Test. Results: There were no statistically significant differences in microleakage (p>0.05) at either enamel or dentine margins among experimental groups. Lased groups resulted with statistically significant less microleakage compared to controls at both enamel and dentine margins in Groups 4 and 6 (p<0.05). Conclusions: 2,5W-20Hz and 3W-20Hz Er,Cr:YSGG laser irradiation may be an alternative to the conventional diamond bur for prevention of microleakage of compomer restorations.

Effect of Synthetic Tissue Fluid on Microleakage of Grey and White Mineral Trioxide Aggregate as Root-End Filling Materials : An in Vitro Study

The success of endodontic surgery has been shown to depend partly on the apical seal. Grey mineral trioxide aggregate (GMTA) produces hydroxyapatite twice as often as white mineral trioxide aggregate (WMTA) when suspended in a phosphate buffered saline (PBS) solution. The aim of this in vitro study was to compare the microleakage phenomenon of gray and white mineral trioxide aggregates as root-end filling materials after immersion in synthetic tissue fluid (STF). 55 single-rooted extracted maxillary anterior human teeth were divided into two experimental groups of 20 teeth each, plus 3 groups of 5 teeth each as two negative and one positive control groups. The root canals were cleaned, shaped, and laterally compacted with gutta-percha. The root ends were resected and 3 mm deep cavities were prepared. The root-end preparations were filled with GMTA or WMTA in the experimental groups. Leakage was determined using a dye penetration method. Data were analysed using analysis of variance (ANOVA) at the 0.05 level of significance. The mean dye leakage was 0.40 ± 0.1 mm for GMTA and 0.50±0.1 mm for WMTA groups, respectively. There was no significant difference between the two experimental groups (P = 0.14). Despite the different properties and behaviours of GMTA and WMTA in STF, there were no significant differences in microleakage when using GMTA or WMTA.

Microleakage of endodontically treated teeth restored with 3 different adhesive systems and 4 different fiber-reinforced posts

Despite recent advances in adhesive dentistry, fiber-reinforced post/resin cement/dentin adhesive combinations are not able to prevent microleakage. While studies have examined microleakage in endodontically treated teeth restored with posts and cores, microleakage among post and adhesive systems remains a concern. This study compared the sealing properties of 4 adhesively luted post systems: glass fiber, quartz-glass fiber, zirconia-glass fiber and polyethylene fiber posts. Forty-eight permanent maxillary central incisors were divided into 4 groups (n=12). Post space was prepared and each post was adhesively luted with 1 of 3 systems: a 1-stage self-etch, a 2-stage total-etch, and a 3-stage total-etch adhesive. The specimens were separately immersed in freshly prepared 2% methylene blue solution for 1 week. The cleaned specimens were then embedded in autopolymerizing acrylic resin. The teeth were horizontally sectioned into apical, middle, and coronal portions. An occlusal view of each section was digitally photographed with a stereomicroscope. The methylene blue-infiltrated surface for each specimen was measured and data were collected with software. Dye penetration was estimated as the ratio of the methylene blue-infiltrated surface to the total dentin surface. Nonparametric data were analyzed with the Kruskal-Wallis test (α=.05). The Mann-Whitney U-test was used to compute multiple pairwise comparisons that identified differences among groups. Dentin-luting agent and post interfaces were evaluated with a scanning electron microscope. Significant differences in adhesive and post systems were observed in all sectioned regions (P<.05). There were significant differences between the apical and coronal sections of each post type, and between the following pairs: middle versus coronal sections of zirconia-glass fiber and glass fiber posts and apical versus middle sections of quartz-glass fiber and polyethylene fiber posts (P<.05). No significant differences were found among post types. The variables of middle section and 3-stage adhesive produced significant differences in microleakage between the following post pairs: zirconia-glass fiber versus quartz-glass fiber, zirconia-glass fiber versus polyethylene fiber, and quartz-glass fiber versus polyethylene fiber (P<.05). The 3-stage adhesive and zirconia-glass fiber posts demonstrated the least microleakage.

In vitro study of microleakage of different techniques of surface preparation used in pits and fissures

The purpose of this in vitro study was to evaluate the effect of different techniques of surface preparation on the microleakage of a sealant applied with traditional acid etching and self-etched bonding agent. A total of 60 extracted third molars were randomly assigned into six groups (n = 10/each). The occlusal surfaces were sealed with a sealant (Clinpro) after one of the following pretreatments: (1) phosphoric acid etching; (2) Prompt L-Pop; (3) laser + etching; (4) laser + Prompt L-Pop; (5) air abrasion + etching; (6) air abrasion + Prompt L-Pop. The specimens were immersed in a 0.5% basic fuchsin solution. Buccolingual cuts parallel to the long axis of the tooth were made. The surfaces were scored 0--2 for extent of microleakage using a microscope and the data were analyzed statistically. The poorest results were obtained with laser + Prompt L-Pop which showed a greater number of specimens with microleakage (80%). Air abrasion surface preparation + phosphoric acid etching showed less microleakage than the other groups (40%). Kruskal--Wallis and t-tests revealed no significant difference in microleakage between six groups. conclusion: The self-etching adhesive studied seems an attractive alternative to the acid-etch technique for sealant application in young children where simplifications in the clinical procedure are warranted. No significant difference was noted between the different types of enamel preparation before fissure sealant.

Effect of Three Different Mouthrinses on Microleakage of Composite Resin Restorations with Two Adhesive Systems after Bleaching with 10% Carbamide Peroxide

The aim was to evaluate the effects of Oral-B (OB), Listerine (LN) and Rembrandt Plus (RM) mouthrinses on microleakage of composite resin restorations bonded with two adhesive systems after bleaching with 10% carbamide peroxide. A total of 60 Cl V cavities were prepared on human premolars. The occlusal and gingival margins were placed 1 mm occlusal to and apical to CEJ respectively. The teeth were randomly divided into two groups based on the adhesive system used: Excite (EX) and Clearfil SE Bond (CSE) groups. After composite resin restoration of cavities, thermocycling and bleaching with 10% carbamide peroxide for 2 hours daily for 14 days, the teeth in each adhesive group were further subdivided into three subgroups and were immersed for 12 hours in the three OB, RM and LN mouthrinses. The teeth were then placed in 2% basic fuschin for 24 hours. After dissecting the teeth, microleakage was evaluated under a stereomicroscope at 16×. Data was analyzed with multifactor ANOVA and Bonferroni test at p < 0.05. Microleakage with EX was significantly higher than that with CSE (p = 0.009). Microleakage at gingival margins was significantly higher than that at occlusal margins (p = 0.15). Microleakage with OB was higher than that with LN (p = 0.02). However, there were no significant differences in microleakage between LN and RM (p = 1) and between RM and OB (p = 0.15). In addition, with the EX adhesive system, microleakage with OB was higher than that with LN and RM (p = 0.02). In the present study, microleakage of composite resin restorations was influenced by the type of the adhesive system, mouthrinse type and the location of the cavity margin. Use of some mouthrinses, such as OB after bleaching can increase postrestoration microleakage of resin composite restorations bonded with etch-and-rinse adhesive systems.

Evaluation of the Apical Seal in Root Canals Prepared with Rotary ProTaper Files and Obturated by Different Methods

Aims: The aim of this in vitro study was to evaluate the apical sealing ability of matched-taper Single- cone, Thermafil, and Cold lateral condensation obturations. Materials and Methods: Thirty-six ex- tracted human lower canine teeth were instrumented to size (F3) with ProTaper rotary instruments after cutting of their crowns to the cement-enamel junction CEJ. The working length was determined for each tooth. The teeth were divided into (3) groups (10) of each and (6) teeth were used as a positive and negative control groups. The teeth were obturated with matched-taper Single-cone, Thermafil, and lateral condensation techniques. Tgadseal was used as a root sealer in this study. A die penetration method was used to evaluate the apical seal using a stereomicroscope at 40X magnification. One-way analysis of variance and Duncan's tests were used for statistical analysis. Results: The statistical anal- ysis of the results demonstrated that there was no statistically significant difference in microleakage between the lateral condensation and Thermafil groups. The matched taper single cone showed the least microleakage with a significant difference than the other two groups. Conclusions: The apical sealing ability of Matched-taper Single-cone obturation was better than the lateral condensation and Thermafil techniques when the root canal was prepared using a ProTaper rotary instrumentation.

Marginal, Internal Fit and Microleakage of Zirconia Infrastructures: An In-Vitro Study

This in-vitro study compared the marginal and internal fit and also the microleakage of zirconia infrastructures (Procera All-Zircon, Cercon Smart Ceramics) in contrast to heat-pressed ones (Empress 2).Thirty maxillary premolars (n=30) were divided into three groups (n=10) and prepared with individual chamfer preparations by using the silicone index method. Plaster dies of 10 individual preparations were allocated to each coping fabrication method of computer-aided design and computer-aided manufacturing (Procera), computer-aided manufacturing (Cercon) and heat pressing (Empress 2) as the control. All the specimens were kept in distilled water at room temperature for four weeks after cementation with dual-curing resin cement (Variolink II, Ivoclar-Vivadent). They were then thermocycled between 5°C to 55°C for 5000 cycles with a 20-second dwell time and immersed in 0.5% basic fuchsin for 48 hours. The cemented specimens were separated into two halves vertically in the midvestibulo-palatal direction. The specimens were examined under a computer-aided stereomicroscope to evaluate both the internal and marginal fit. Marginal and internal gap widths were measured at 100× magnification. The specimens were evaluated for microleakage under a stereomicroscope at 100 × magnification. Selected specimens from each group were also examined using a scanning electron microscope. Fitting accuracy data were analyzed statistically with the Welch test and the Post-hoc Dunnett C-test (p<0.05). The microleakage data were analyzed with the Kruskal-Wallis test. Special software (SPSS/PC+ Version 10.0, SPSS, Chicago, IL, USA) was used for statistical evaluations.Differences between the marginal and internal fitting accuracy of the tested non-veneered infrastructures were found to be statistically significant (p<0.05). However, there were no significant differences in microleakage among the groups (p=0.273).

The Effect of Oxalate Desensitizers on the Microleakage of Resin Composite Restorations Bonded by Etch and Rinse Adhesive Systems

This in vitro study evaluated the effect of an oxalate desensitizer (OX) on the marginal microleakage of resin composite restorations bonded by two three-step and two two-step etch and rinse adhesives. Class V cavities were prepared on the buccal surfaces of 126 extracted premolars at the cementoenamel junction and randomly divided into nine groups of 14 each. In the control groups (1-4), four adhesives were applied, respectively, including Adper Scotchbond Multi-Purpose (SBMP), Optibond FL (OBFL), One-Step Plus (OS) and Excite (EX). In the experimental groups (5-8), the same adhesives, in combination with OX (BisBlock), were applied. And, in one group, OX was applied without any adhesive, as the negative control group (9). All the groups were restored with a resin composite. After 24 hours of storage in distilled water and thermocycling, the samples were placed in 1% methylene blue dye solution. The dye penetration was evaluated using a stereomicroscope. The data were analyzed using non-parametric tests. The OX application, in combination with OBFL and EX, resulted in significantly increasing microleakage at the gingival margins (p < 0.05), while it had no effect on OS and SBMP (p > 0.05). At the occlusal margins, no significant difference in microleakage was observed after OX application for each of four adhesives (p > 0.05).

Efficacy of Composite Restorative Techniques in Marginal Sealing of Extended Class V Cavities

Objectives. To compare the efficacy of three placement techniques in marginal sealing of Class V composite restorations extending onto the root. Materials and Methods. Class V cavities were prepared on buccal surfaces of 30 extracted human molars, with gingival margins 1.5 mm on the root. Prepared teeth were randomly assigned into 3 groups of 10 each and restored with Single Bond/Filtek Supreme using following techniques; Group I: oblique; Group II: occlusogingival; and Group III: split-increment. After restoration finishing, teeth were thermocycled, and immersed in 2% methylene blue dye for 24 h. Teeth were sectioned buccolingually. Digital photographs were made of sectioned surfaces using digital camera fitted on stereomicroscope. Microleakage was scored at occlusal and gingival margins using 0–3 scale. Dye penetration depth (DPD) at both margins was also measured using AnalySIS software. Data were analyzed using one-way ANOVA and Bonferroni multiple comparison test. Results. 5% of occlusal margins in Groups I and III had 50 μm average (DPD). In Group II, only 10% of occlusal margins showed dye penetration, with 60 μm average depth. For gingival margins, Groups I and III presented dye penetration in 55% of specimens, with 220 and 150 μm average (DPD), respectively. Group II had 60% of gingival margins, with 230 μm average (DPD). There was no significant difference in microleakage at occlusal and gingival margins in all groups. Dye penetration was larger at gingival than at occlusal margins (P < .001). Conclusion. None of placement techniques produced gap-free margins. Oblique and occlusogingival techniques exhibited higher degrees of microleakage at occlusal and gingival margins, as compared to that of split-increment technique. Splitting flat composite increment by diagonal cut, prior to light-curing, preserved bonded gingival margin integrity and reduced microleakage.