Effect of Fiber Nets, Application Techniques and Flowable Composites on Microleakage and the Effect of Fiber Nets on Polymerization Shrinkage in Class II MOD Cavities

Antibacterial Activity of the Vancomycin and Cefotaxime-Incorporated Total Etch Adhesive System - An In Vitro Study

Background

Marginal failure at the resin dentin interface promotes biofilm formation, which further leads to secondary caries and hypersensitivity. This likelihood also increases if residual bacteria are present following cavity preparation. In order to achieve a proper biological seal without jeopardizing bonding, efforts were made to functionalize the adhesive system with antibacterial activity. Aim and objectives: To appraise the antibacterial activity of a total-etch adhesive system against S. mutans with and without incorporation of antibiotics Vancomycin and Cefotaxime.

Materials and Method

A commercially available 5th-generation total-etch bonding agent (Te-Econorm) was used. S. mutans broth had been standardized and streaked over Muller-Hinton agar culture medium and round wells about 6 mm in diameter were made in the centre of the agar plates. Each experimental group comprised 10 samples, which include: Group 1 - 30µg Cefotaxime, Group 2- 30µg Cefotaxime + Bonding agent, Group 3- 30µg Vancomycin, Group 4- 30µg Vancomycin + Bonding agent, Group 5- Bonding agent, and Group 6- No material. Inoculated culture plates were examined for the zone of inhibition after incubation at 37° C for 24 hours.

Results

There was a significant difference in the mean diameter of zone of inhibition (p=0.000), with the maximum exhibited by Group 4, followed by Group 3 and Group 2. The least zone of inhibition was exhibited by Groups 1 and 5. The negative control showed no zone of inhibition.

Conclusion

The combination of Vancomycin and bonding agent had superior antibacterial activity against S. mutans in comparison to cefotaxime and bonding agent.

The Effect of Different Intermediary Layer Materials Under Resin Composite Restorations on Volumetric Cuspal Deflection, Gap Formation, and Fracture Strength

This study investigated the effect of different intermediary layer materials under class II mesio-occluso-distal (MOD) resin composite restorations on volumetric cuspal deflection, gap formation, and fracture strength. In total, 32 sound human maxillary premolars were used. After large, standardized Class II MOD cavities were prepared, a universal adhesive (Clearfil Universal Bond Quick, Kuraray) was applied. The premolars were randomly allocated into four groups according to different intermediary layer materials (n=8): Group Z250 (control)/micro-hybrid composite (Filtek Z250, 3M ESPE); Group EST/low-viscosity bulk-fill resin composite (Estelite Bulk Fill Flow, Tokuyama Dental Corp) + micro-hybrid composite; Group NOV/nanofiber-reinforced low-viscosity composite (NovaPro Flow, Nanova) + micro-hybrid composite; and Group RIB/polyethylene fiber [Ribbond, Ribbond Inc] + micro-hybrid composite. Distilled water was used for storage for 24 hours. Using microcomputed tomography (micro-CT), the teeth were scanned immediately after cavity preparation (T0), then 24 hours after restorative procedures (T1). Volumetric cuspal deflection in cubic millimeters (mm3) was analyzed on the palatal and buccal regions of each restoration individually at T0 and T1 scans. Gap formation (mm3) was evaluated to quantify the volume of black spaces at the tooth-resin interface on the T1 scan. After these scans, using a universal testing machine, the teeth were subjected to a fracture strength test (0.5 millimeters/minute [mm/min]). The fracture surfaces were analyzed with a stereomicroscope. The data were analyzed using the Kruskal-Wallis, one-way analysis of variance (ANOVA), and Dunn's tests (p< 0.05). No significant differences in volumetric cuspal deflection and fracture strength were detected for all tested groups (p>0.05). Group RIB exhibited significantly higher gap formation values in comparison with all other groups (p<0.05). Predominant failure mode was favorable.

Effect of a fiber-reinforcing technique for direct composite restorations of structurally compromised teeth on marginal microleakage

OBJECTIVES

To evaluate if the marginal microleakage of extensive Class I composite resin restorations can be affected by applying ultra-high-molecular-weight polyethylene (UHMWPE) fibers with the wallpapering technique combined with different restorative materials and methods.

MATERIALS AND METHODS

A 120 human molars were selected and one extensive Class I cavity was prepared on the occlusal surface of each tooth. The specimens were divided into 12 groups (n = 10) according to the type of restorative material (Filtek Z550, Beautifil II LS or Beautifil Bulk Restorative), the use or not of reinforcing fibers (ribbond) and the applied restorative technique (incremental or bulk). The specimens were subjected to thermocycling and then immersed into a 50 wt% silver nitrate solution following a dying protocol. Subsequently, the teeth were prepared for SEM observations to evaluate the extent of marginal microleakage.

RESULTS

Three-way ANOVA revealed that the type of material, the use of ribbond fibers and the type of restorative technique significantly affected marginal microleakage (p < 0.001). Application of ribbond fibers decreased marginal microleakage to all tested restorative materials, regardless of the restorative technique, in a range of 31.2-81.4%. In the groups with no-use of ribbond fibers, among the materials there were no significant differences in microleakage when the teeth were restored with the incremental technique (p > 0.05).

CONCLUSIONS

The use of UHMWPE fibers with wallpapering technique in Class I composite restorations may be an effective method to reduce marginal microleakage, regardless of the selected restorative technique or the material.

CLINICAL RELEVANCE

Clinicians may be encouraged to utilize reinforcing fiber restorative techniques for direct restorations of structurally compromised teeth as a valid alternative to indirect restorations.

Effect of Fiber Reinforcement Type on the Performance of Large Posterior Restorations: A Review of In Vitro Studies

To reinforce extensively prepared cavities, different types of fiber reinforcement are utilized. Polyethylene and glass fibers are the most commonly used fibers in that purpose; each type has its own advantages over the other type. Therefore, the aim of this study is to review the literature to evaluate and compare the influence of different fiber reinforcement types on the performance of posterior large composite restorations. Two independent authors performed a comprehensive literature search using MEDLINE/PubMed, Google Scholar, and a manual search for cross references until July 2021. Authors selected only studies that contain comparisons between glass (continuous or short) and polyethylene (woven) fiber-reinforced composites (FRCs) in posterior cavities of human teeth, and that report the effect of fiber inclusion on fracture resistance, microleakage, and marginal adaptation of restorations. A number of 2711 potentially relevant articles were obtained from the electronic search. After extensive assessment, 2696 articles were ineligible to be included in the review, and only 15 articles met the inclusion criteria. Four out of nine studies, which tested the fracture resistance of FRC restorations, revealed similar performance of the glass and polyethylene fibers. The rest of the studies (n = 5) revealed statistically significant differences between the two types of fiber reinforcement, with the majority showed superior reinforcement of glass fiber. Moreover, the reviewed studies revealed that, using fibers within the composite restorations would reduce the microleakage and improve the marginal adaptation of the restoration regardless of the fiber type. FRCs tend to strengthen the restorations of structurally compromised teeth and improve their performance compared to plain composite restorations.

Comparison of fiber-reinforced composite and nanohybrid resin impregnated with glass fibers as postendodontic restoration in molars – A clinical study

Background:

Aim:

Materials and Methods:

Statistical Analysis:

Results:

Conclusion:

Ex vivo fracture resistance of teeth restored with glass and fiber reinforced composite resin

OBJECTIVES

This study aims to compare the ex vivo fracture resistance of root canal treated (RCT) teeth restored with four different types of fibers under composite resin.

SUBJECTS AND METHODS

One hundred and forty extracted mandibular first molar teeth were assigned to seven groups (n = 20/group). Group 1 was the control group. In groups 2-7, endodontic access and standard Mesio-occluso-distal (MOD) cavities were prepared. Following RCT, group 2 was left unrestored. In group 3, flowable composite resin (FCR) was used to line the cavities and restored with composite resin. In groups 4,5,6 and 7, Ribbond, Everstick, Dentapreg and Bioctris fibers were inserted in flowable resin and restored respectively.

RESULTS

All the groups restored with fiber reinforced composite displayed higher fracture resistance than the group restored with only composite resin (p < 0.001). In addition, Groups restored with Everstick and Bioctris (Groups 5 and 7) showed higher fracture resistance when compared to Ribbond and Dentapreg (Groups 4 and 6).

CONCLUSION

E glass fibers demonstrated highest fracture resistance and hence can be preferred over other fiber types to reinforce RCT teeth with weakened crown structures.

Comparative evaluation between glass and polyethylene fiber reinforced composites: A review of the current literature

BACKGROUND

Fiber reinforced composite (FRC) is a promising class of material that gives clinicians alternative treatment options. There are many FRC products available in the market based on either glass or polyethylene fiber type. The aim of this study was to present a comparison between glass and polyethylene fiber reinforced composites based on available literature review.

MATERIAL AND METHODS

A thorough literature search, with no limitation, was done up to June 2017. The range of relevant publications was surveyed using PubMed and Google Scholar. From the search results, articles related to our search terms were only considered. An assessment of these articles was done by two individuals in order to include only articles directly compare between glass and polyethylene FRCs. The search terms used were "fiber reinforced dental composites" and "glass and polyethylene fibers in dentistry".

RESULTS

The search provided 276 titles. Full-text analysis was performed for 29 articles that met the inclusion criteria. Most were laboratory-based research with various test specimen designs prepared according to ISO standard or with extracted teeth and only three articles were clinical studies. Most of studies (n=23) found superior characteristics of glass FRCs over polyethylene FRCs.

CONCLUSIONS

Significant reinforcement differences between commercial glass and polyethylene fiber reinforced composites were found. Key words:Fiber reinforced composite, glass fiber, polyethylene fiber.

An In vitro Evaluation of Microleakage Associated with Three Different Compomer Placement Techniques in Primary Molars

Background:

Microleakage is one of the most frequently encountered problems in posterior tooth-colored restorations. Efforts to decrease this problem with resin restorations include techniques for reducing the ratio of bonded to unbonded restoration surfaces and following strategic incremental placement techniques to reduce residual stress at tooth-restoration interface which reduces the C-factor, hence microleakage.

Aim:

The present study aimed to evaluate microleakage associated with three placement techniques for compomer restorations in primary molars.

Design and Methodology:

This in vitro experimental study assessed the microleakage associated with bulk-fill, horizontal-incremental, and oblique-incremental compomer placement techniques in primary molars. Ninety specimens were divided into three groups of thirty for each of the placement techniques.

Results:

Nearly 86.6% of the specimens presented with microleakage involving the entire axial wall and pulpal floor in the bulk-fill group, whereas 56.6% and 46.6% of the specimens in the horizontal-incremental and oblique-incremental groups showed microleakage up to two-third and one-third of the axial walls, respectively. A significant difference in scores was observed between groups (P < 0.001).

Conclusion:

Microleakage was observed with all the three techniques but was comparatively lower with the incremental placement techniques. The oblique-incremental technique offered the least microleakage.

Investigation of the Er: YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities restored with different flowable composites

The purpose of this study was to evaluate the efficiency of the Er:YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities. Group 1: bur preparation (bp) + Vertise Flow (VF); Group 2: laser preparation (lp) + VF; Group 3: bp + Adper Easy One (AEO) + Filtek Ultimate Flowable Composite (FUFC); Group 4: lp + AEO + FUFC; Group 5: bp + Clearfil S3 Bond (CSB) + Clearfil Majesty Flow (CMF); Group 6: lp + CSB + CMF. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < .05). No significant difference was observed among all groups in terms of occlusal and cervical surfaces, respectively (p > .05). The use of the Er:YAG laser for cavity preparation with different adhesive systems and flowable composites did not influence microleakage.

Push-out bond strength of different intracanal posts in the anterior primary teeth according to root canal filling materials

Background:

This study was carried out to evaluate the effect of root canal filling on the bond strength of three intracanal posts in the primary incisors.

Materials and Methods:

Sixty primary incisors were prepared and then divided into two groups (n = 30). The first group canals obturated with zinc oxide eugenol (ZOE) and Group 2 canals obturated with Metapex. Further, the two group categories were divided into three subgroups (n = 10): (1) short composite post (SCP), (2) glass fiber posts (GFPs) cemented with flowable composite, and (3) GFP with glass ionomer cement (GFP + GIC). The push-out test was performed with a universal testing machine. The results were statistically analyzed with two-way analysis of variance.(α = 0.05).

Results:

The mean bond strength of the first group obturated with ZOE was lower than that of the second group obturated with Metapex (P = 0.046). Moreover, from a statistical point of view, in all three subgroups, the correlation of mean push-out bond strength between SCP and GFP coated with flowable composite was not substantial at P = 0.97. However, the mean bond strength of SCP was in fact significantly greater than that of the GFP coated with GIC since P = 0.034.

Conclusion:

Using ZOE resulted in the significant reduction of the mean bond strength of the intracanal posts when utilized in the primary anterior teeth. Likewise, SCP and GFP coated with flowable composite showed higher push-out bond strengths for restoring primary anterior teeth.

Effect of different parameters of Er:YAG laser irradiations on class V composite restorations: A scanning electron microscopy study

The purpose of this study was to compare different parameters of Er:YAG laser irradiations on the marginal microleakage of Class V resin composite restorations. A total of 45 extracted premolars were selected for the study. Class V cavities prepared on both buccal and lingual surfaces of teeth by Er:YAG laser or bur and divided into nine groups. The occlusal margins were in enamel and the cervical margins were in cementum. Group-1: bur preparation; Group-2: laser preparation (lp) (600 mJ/5 Hz); Group-3: lp (300 mJ/10 Hz); Group-4: lp (200 mJ/15 Hz); Group-5: lp (150 mJ/20 Hz); Group-6: lp (200 mJ/20 Hz); Group-7: lp (300 mJ/14 Hz); Group-8: lp (400 mJ/10 Hz); Group-9: lp (700 mJ/5 Hz). All teeth were stored in distilled water at 37°C for 24 h, then thermocycled 1,000 times (5-55°C). Five teeth from each group were chosen for the microleakage investigation and two teeth for the scanning electron microscope (SEM) evaluation. Teeth, which were prepared for the microleakage test were immersed in 0.5% methylene blue dye for 24 h. After immersing, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < 0.05) except for Group 6 (p > 0.05). No significant difference was observed among groups in terms of occlusal and cervical surfaces, separately (p > 0.05). It may be concluded that the cavities prepared by Er:YAG laser showed higher degree of microleakage than bur prepared at cervical regions. Different parameters of Er:YAG laser irradiations affected microleakage. SCANNING 38:434-441, 2016. © 2016 Wiley Periodicals, Inc.

The effects of cavity-filling techniques on microleakage in class II resin restorations prepared with Er:YAG laser and diamond bur: A scanning electron microscopy study

The purpose of this study was to investigate how two cavity-filling techniques affect microleakage in class II resin restorations prepared with Er:YAG laser and diamond bur. Standard MO and DO cavities were prepared in 20 extracted third molars, each randomly assigned to either Group-1 [Herculite XRV Ultra-bur-prepared cavity(bp)], Group-2 [Herculite XRV Ultra-laser-prepared cavity(lp)], Group-3 (SonicFill-(bp)], or Group-4 [SonicFill-(lp)]. For Groups 2 and 4, cavities were prepared by using an Er:YAG laser with a wavelength of 2.94 μm, output power of 200 mJ/pulse, and repetition rate of 20Hz. Teeth were restored with a one-step, self-etch adhesive material (OptiBond All-in-One), a nanohybrid composite (Herculite XRV Ultra), and a bulk-fill composite (SonicFill) according to the manufacturer's instructions. Five teeth from each group were chosen for microleakage investigation and two teeth for scanning electron microscope evaluation. Statistical analysis was performed by using Kruskal-Wallis test. Pair-wise comparisons were performed by Mann-Whitney U test with Bonferroni correction (p < 0.05). The statistical analysis of data revealed greater microleakage in cervical versus occlusal regions in all groups (P < 0.05). Group-2 yielded a higher degree of marginal leakage than Group-3 in terms of occlusal surfaces (p < 0.05). For cervical regions, a statistically significant difference was observed between Groups 2 and 3 as well as Groups 2 and 4 (p < 0.05). Group-3 exhibited significantly better marginal sealing than Group-1 in the cervical region (p < 0.05). The cavities prepared using an Er:YAG laser showed greater microleakage than those conventionally prepared using burs regardless of restorative material at both occlusal and cervical margins. SCANNING 38:389-395, 2016. © 2015 Wiley Periodicals, Inc.

Three-year clinical evaluation of class II posterior composite restorations placed with different techniques and flowable composite linings in endodontically treated teeth

OBJECTIVE

The objective of this study is to evaluate the clinical performance of direct resin composite restorations placed with different techniques (incremental or bulk) and different flowable linings (conventional or bulk-fill) in endodontically treated teeth.

MATERIALS AND METHODS

Forty-seven pair class II (mesio-occlusal or disto-occlusal) composite restorations were placed in 37 patients. In all cavities, Adper Single Bond 2 was used. In one of the cavities of each pair, a conventional flowable composite, Aelite Flo, was applied in approximately 2 mm thick, and the remaining cavity was restored incrementally with GrandioSO. In the second cavity, a bulk-fill flowable composite, x-tra base, was applied in approximately 4 mm thick in bulk increments and the remaining 2-mm occlusal part of the cavity was restored with GrandioSO. All cavities were restored with open-sandwich technique by the same operator. At baseline and after 6-month, 1-, 2-, and 3-year follow-up visits, restorations were evaluated by modified USPHS criteria.

RESULTS

At 3-year recall, 33 restorations with Aelite Flo lining and 33 with x-tra base lining were available. Two restorations from each group (6.0 %) were scored as Bravo in terms of surface texture. One restoration's color match from x-tra base group scored as Bravo (3.0 %). All other evaluated criteria were scored as Alfa (100 %) for all restorations. No statistically significant difference between the two groups was found in all evaluated criteria during 3-year period (p > 0.05).

CONCLUSION

Bulk-filling technique showed clinically acceptable performance comparable to the incremental technique.

CLINICAL RELEVANCE

Restorations placed with bulk-filling technique with x-tra base lining and incremental technique with a conventional flowable lining showed highly clinical performance over 3-year period.

Effects of Preheated Composite on Micro leakage-An in-vitro Study

INTRODUCTION

Resin composites have been the pinnacle of direct esthetic restorations ever since its discovery. However, it comes with its own disadvantages. Post-operative sensitivity and marginal discoloration frequently occur due to polymerization shrinkage and micro leakage, which is the major cause of failure in resin composite restorations.

AIM

To evaluate the effects of preheated composite at different temperatures on microleakage.

MATERIALS AND METHODS

A total of 60 extracted non-carious human premolars were collected and class 1 cavity (1.5x4x 3mm) was prepared in each and were randomly divided into three groups. Group 1 (n=20) was filled with microhybrid resin composite (Heraeus Charisma Smile) at room temperature. Group 2 (n=20) was filled with the same resin composite which was preheated to 50°C and Group 3 (n=20) was filled with resin composite preheated to 60°C. Teeth were subjected to a thermocycling regime (500X, 5 - 55°C), followed by a dye infiltration by immersing in basic fuschin for 24 hours. The tooth was sectioned longitudinally and the extent or absence of micro-leakage was determined by the amount of dye penetration along the resin composite-tooth interface using a confocal microscope.

RESULTS

There was minor micro-leakage detected at the occlusal margin of the control tooth specimen. The sample with preheated composite restoration at 50°C showed an intact tooth-restoration interface with no micro leakage. However, the preheated composite at 60°C showed large amount of microleakage.

CONCLUSION

Under the current limitation of the study, preheated composite at 50°C showed the least micro-leakage.

Comparison of total-etch, self-etch, and selective etching techniques on class V composite restorations prepared by Er:YAG laser and bur: a scanning electron microscopy study

The purpose of this study was to compare total-etch, self-etch, and selective etching techniques on the marginal microleakage of Class V composite restorations prepared by Er:YAG laser and bur. Class V cavities prepared on both buccal and lingual surfaces of 30 premolars by Er:YAG laser or bur and divided into six groups. The occlusal margins were in enamel, and the cervical margins were in cementum. Group-1: bur preparation(bp)+Adper Single Bond 2 (ASB)+Filtek Z550 (FZ); Group-2: laser preparation(lp)+(ASB)+(FZ); Group-3: bp + Clearfil S3 Bond Plus (CSBP)+(FZ); Group-4: lp+(CSBP) (FZ); Group-5: bp + acid etching+(CSBP)+(FZ); Group-6: lp + acid etching+(CSBP)+(FZ). All teeth were stored in distilled water at 37°C for 24 hr, and then thermocycled 1000 times (5-55°C). Five teeth from each group were chosen for the microleakage investigation, and two teeth for the scanning electron microscope evaluation. Teeth which were prepared for the microleakage test were immersed in .5% methylene blue dye for 24 hr. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in the cervical regions compared to the occlusal regions in Groups 3, 5, and 6, respectively (p < .05). There is no statistically significant difference in Groups 1, 2, and 4, in terms of cervical regions versus occlusal regions (p > .05). No significant differences were observed among any groups in terms of occlusal and cervical surfaces, separately (p > .05). Different etching techniques did not influence microleakage of Class V restorations prepared by Er:YAG laser and bur.

Effect of fiber reinforcement on microleakage of class II cavities restored with a novel G-aenial posterior composite, silorane composite, and nanohybrid composite: an in vitro comparative study

AIM

The aim of the present study was to compare G-aenial, silorane, and nanoceramic composites and the effect of polyethylene fiber inserts in reducing gingival microleakage in class II composite restorations placed apical to the cementoenamel junction.

METHODS

Standardized class II cavities were prepared on extracted molars and randomly divided into six groups (n = 20 each): group 1, Ceram X mono; group 2, Ceram X mono + Ribbond; group 3, Filtek P90; group 4, Filtek P90 + Ribbond; group 5, G-aenial posterior; and group 6, G-aenial posterior + Ribbond. All specimens were subjected to a thermocycling regime, immersed in 2% methylene blue dye for 24 h, sectioned longitudinally, and examined under a stereomicroscope to assess dye penetration on a six-point scale. The score data were subjected to statistical analysis, whereby the Kruskal-Wallis analysis of variance was used for multiple group comparisons and the Mann-Whitney test for groupwise comparisons at a significance level of P ≤ 0.05.

RESULTS

A statistically-significant decrease in microleakage was found when Ribbond fiber was used: group 2 vs group 1 (P < 0.001), group 4 vs group 3 (P < 0.001), and group 6 vs group 5 (P < 0.001). A significant decrease in microleakage scores was found in the silorane and G-aenial posterior composites when compared to the nanoceramic composite (P < 0.001).

CONCLUSION

The use of polyethylene fiber, silorane composite, and G-aenial posterior composite reduces microleakage in class II composite restorations with gingival margins below the cementoenamel junction.

Retentive strength of different intracanal posts in restorations of anterior primary teeth: an in vitro study

Objectives

To determine the retentive strength and failure mode of undercut composite post, glass fiber post and polyethylene fiber post luted with flowable composite resin and resin-cement.

Materials and Methods

Coronal parts of 120 primary canine teeth were sectioned and specimens were treated endodontically. The teeth were randomly divided into 6 groups (n = 20). Prepared root canals received intracanal retainers with a short composite post, undercut composite post, glass fiber post luted with flowable resin or resin-cement, and polyethylene fiber post luted with flowable resin or resin-cement. After crown reconstruction, samples were tested for retentive strength and failure mode. Statistical analysis was done with one-way ANOVA and Tukey tests (p < 0.05).

Results

There were statistically significant differences between groups (p = 0.001). Mean bond strength in the undercut group was significantly greater than in the short composite post (p = 0.030), and the glass fiber post (p = 0.001) and the polyethylene fiber post group luted with resin-cement (p = 0.008). However, the differences between the undercut group and the groups with flowable composite as the luting agent were not significant (p = 0.068, p = 0.557). Adhesive failure was more frequent in the fiber post groups.

Conclusions

Although the composite post with undercutting showed the greatest resistance to dislodgement, fiber posts cemented with flowable composite resin provided acceptable results in terms of retentive strength and fracture mode.

Efficacy of four lining materials in sandwich technique to reduce microleakage in class II composite resin restorations

OBJECTIVES

The aim of the present study was to evaluate the effect of four different sandwich techniques on gingival microleakage of Class II direct composite resin restorations.

MATERIALS AND METHODS

Fifty sound human premolars were selected and randomly divided into five groups (n=10). Class II box only cavities were prepared in one of the proximal surfaces of each tooth with a gingival margin located approximately 0.5 mm below the cemento-enamel junction. Group A (control) was restored incrementally with composite resin (Tetric Ceram). Groups B, C, D, and E were restored with the sandwich technique using a compomer (Compoglass F), flowable composite resin (Tetric Flow), self-cure composite resin (Degufill SC), or resin modified glass ionomer (Fuji II LC), respectively. After thermal-load cycling, the specimens were immersed in 0.5% basic fuschin for 24 hours. Dye penetration (10(-1) mm) was detected using a sectioning technique. Data were analyzed with repeated measurements and Duncan test at α=0.05.

RESULTS

The least amount of microleakage was detected in the incremental group (1.28 ± 0.98). The sandwich technique using resin modified glass ionomer (7.99 ± 9.57) or compomer (4.36 ± 1.78) resulted in significantly more leakage than did the sandwich technique using flowable (1.50 ± 1.97) or self-cure composite (2.26 ± 1.52).

CONCLUSION

According to the results of this study, none of the four sandwich technique composite resin restorations used in this study could reduce gingival microleakage to a greater degree than the incremental technique.

Influence of fiber inserts, type of composite, and gingival margin location on the microleakage in Class II resin composite restorations

This study evaluated the influence of fiber inserts, type of composites, and location of the gingival seat on microleakage in Class II resin composite restorations. Fifty noncarious human third molars were selected for the study. Standardized Class II box type cavities were prepared on the mesial and distal side of 45 teeth. The gingival margin was placed above the cementoenamel junction (CEJ) on the mesial side and below the CEJ on the distal side. The remaining five teeth received no cavity preparations. The prepared samples were divided randomly on the basis of type of composite and presence or absence of fiber inserts, into four experimental groups of 10 teeth each and two control groups of five teeth each. The groups were defined as follows: group I (n=10) - Z350 XT; group II (n=10) - Z350 XT with fibers; group III (n=10) - P90; group IV (n=10) - P90 with fibers; and group V (n=5) - positive controls, cavities were not restored; group VI (n=5) - negative controls, no cavities were prepared. The samples were stored in distilled water in incubator at 37°C for 24 hours and then subjected to 500 cycles of thermocycling (5°C and 55°C) with a dwell time of 15 seconds. They were then placed in a 2% methylene blue dye solution for 24 hours at 37°C. Samples were sectioned longitudinally and evaluated for microleakage at the occlusal and gingival margin under a stereomicroscope at 20× magnification. Kruskal-Wallis and Mann-Whitney U-tests were used to compare the mean leakage scores. Restorations with gingival margins in enamel showed significantly less microleakage. Significant reduction in microleakage was observed in groups restored with P90 composite than those restored with Z350 XT. No improvement in microleakage was observed with the use of fiber inserts (p>0.05).

Comparative evaluation of microleakage of silorane-based composite and nanohybrid composite with or without polyethylene fiber inserts in class II restorations: an in vitro study

AIM

To evaluate microleakage between nanocomposite and silorane composite in class II restorations with or without a polyethylene fiber insert.

METHODOLOGY

Standardized class II cavities were prepared on extracted molars and randomly divided into 4 groups (n=20 each): group 1, Ceram X mono; group 2, Ceram X mono + Ribbond; group 3, Filtek P90; and Group 4, Filtek P90 + Ribbond. All specimens were subjected to a thermocycling regime, immersed in 2% methylene blue dye for 24 hours, sectioned longitudinally, and examined under a stereomicroscope to assess dye penetration on a six-point scale. The score data were subjected to statistical analysis whereby Kruskal-Wallis analysis of variance was used for multiple group comparisons and the Mann-Whitney test for groupwise comparisons at a significance level of p≤0.05.

RESULTS

A statistically significant decrease in microleakage was found when Ribbond fiber was used with nanoceramic and silorane composite. A highly significant decrease in microleakage scores was found in silorane composite when compared to nanoceramic composite.

CONCLUSION

Use of polyethylene fiber and silorane composite reduces microleakage in class II composite restorations with gingival margins below the cemento-enamel junction.

Prediction and diagnosis of clinical outcomes affecting restoration margins

The longevity of dental restorations is largely dependent on the continuity at the interface between the restorative material and adjacent tooth structure (the restoration margin). Clinical decisions on restoration repair or replacement are usually based upon the weakest point along that margin interface. Physical properties of a restorative material, such as polymerisation shrinkage, water sorption, solubility, elastic modulus and shear strength, all have an effect on stress distribution and can significantly affect margin integrity. This review will focus on two aspects of margin deterioration in the oral environment: the in vitro testing of margin seal using emersion techniques to simulate the oral environment and to predict clinical margin failure and the relationship between clinically observable microleakage and secondary caries. The many variables associated with in vitro testing of marginal leakage and the interpretation of the data are presented in detail. The most recent studies of marginal leakage mirror earlier methodology and lack validity and reliability. The lack of standardised testing procedures makes it impossible to compare studies or to predict the clinical performance of adhesive materials. Continual repeated in vitro studies contribute little to the science in this area. Clinical evidence is cited to refute earlier conclusions that clinical microleakage (penetrating margin discoloration) leads to caries development and is an indication for restoration replacement. Margin defects, without visible evidence of soft dentin on the wall or base of the defect, should be monitored, repaired or resealed, in lieu of total restoration replacement.

Effect of precuring warming on mechanical properties of restorative composites

To investigate the effect of prepolymerization warming on composites' mechanical properties, three composites were evaluated: Clearfil Majesty (CM) (Kuraray), Z-100 (3M/ESPE), and Light-Core (LC) (Bisco). Specimens were prepared from each composite at room temperature as control and 2 higher temperatures (37°C and 54°C) to test surface hardness (SH), compressive strength (CS), and diametral tensile strength (DTS). Data were statistically analyzed using ANOVA and Fisher's LSD tests. Results revealed that prewarming CM and Z100 specimens significantly improved their SH mean values (P < 0.05). Prewarming also improved mean CS values of Z100 specimens (P < 0.05). Furthermore, DTS mean value of CM prepared at 52° was significantly higher than that of room temperature specimens (P < 0.05). KHN, CS, and DTS mean values varied significantly among the three composites. In conclusion, Prewarming significantly enhanced surface hardness of 2 composites. Prewarming also improved bulk properties of the composites; however, this improvement was significant in only some of the tested materials.

In vitro comparison of microleakage of posterior resin composites with and without liner using two-step etch-and-rinse and self-etch dentin adhesive systems

BACKGROUND AND AIMS

Composite restorations frequently have gingival margins apical to the cemento-enamel junction (CEJ). Microleakage at the cementodentinal margins is one of the most important causes of failure in these restorations. The current study evaluated microleakage at the occlusal and gingival margins of Class II packable composite restorations using resin-modified glass ionomer and flowable composite as liners, using the two-step etch-and-rinse and self-etch dentin-bonding systems.

MATERIALS AND METHODS

This in vitro study was carried out on 48 intact human premolars. Class II preparations were made with the gingival margins placed 1.0 mm apical to the CEJ. The teeth were randomly assigned to six groups of 16 boxes and restored using the following techniques: Group 1: Single Bond (3M ESPE) + Filtek P60 (3M ESPE); Group 2: Clearfil SE Bond (Kuraray) + Filtek P60; Group 3: Single Bond + Filtek Flow (3M ESPE) + Filtek P60; Group 4: Clearfil SE Bond + Filtek Flow + Filtek P60. Group 5: Single Bond + Fuji II LC (GC) + Filtek P60; Group 6: Clearfil SE Bond + Fuji II LC + Filtek P60. The restorations were thermocycled for 1000 cycles at 5{degree sign}C and 55°C, soaked in 2% methylene blue for 48 hours, then sectioned mesiodistally and viewed under a stereomicroscope for leakage at the gingival margin. The data were statistically analyzed using the Kruskal-Wallis, two-way ANOVA and Mann-Whitney U-tests.

RESULTS

The resin-modified glass-ionomer liner demonstrated significantly less leakage than flowable composite (p<0.05). There was no difference between restorations with flowable resin composite liners and those without the liner; in addition, no significant difference was observed between the two kinds of adhesive systems.

CONCLUSIONS

The current study supports the use of resin-modified glass ionomer as a liner in closed-sandwich technique to decrease microleakage of Class II packable composite restorations, applying either the two-step etch-and-rinse or the self-etch dentin adhesive system.