In Vitro Microleakage and Fracture Resistance of "Infinity Edge" and Cusp Reduction Preparation Designs for Moderate-sized Class II Composites.

AIM: This study aimed to evaluate the marginal microleakage and maximum occlusal fracture loads and fracture modes of two novel class II preparation designs, "infinity edge" and the "2.5 mm cusp reduction" preparations as compared to a traditional class II preparation without cuspal involvement. MATERIALS AND METHODS: Thirty extracted human mandibular molars were prepared for moderate-sized class II restorations with extensions into all occlusal grooves. Of these, ten class II preparations served as control. Ten were modified for a 2.5 mm even reduction of the cusps adjacent to the interproximal box. An additional 10 preparations were modified with an "infinity edge" bevel on the interproximal and occlusal portions. All teeth were restored utilizing a flowable bulk-fill composite in the apical portion of the interproximal box and 2-4 mm of heated bulk-fill composite in one increment for the remainder. All groups were cyclic loaded and thermocycled, then imaged with microcomputed tomography (µCT) before and after infiltration with a silver nitrate solution. Images were subtracted to obtain volumetric measurements of microleakage and reported as a percentage of the total volume from the apical extent of the proximal box. All groups were loaded to failure and fracture load and mode were recorded. RESULTS: No significant differences were found in microleakage volume as a percentage of total tooth volume; however, the "infinity edge" group had significantly greater microleakage in the proximal box compared to the traditional class II group. No significant differences were found in fracture load or mode between the groups. CONCLUSION: Traditional class II, 2.5 mm cuspal reduction, and "infinity edge" preparation designs have similar fracture loads as well as volumes of microleakage; however, an "infinity edge" preparation has a higher ratio of microleakage in the proximal box. CLINICAL SIGNIFICANCE: Clinicians should carefully consider the use of "infinity edge" margins, particularly on dentin in the apical extent of the proximal box. How to cite this article: Watson JC, Lien W, Raimondi JC, et al. In Vitro Microleakage and Fracture Resistance of "Infinity Edge" and Cusp Reduction Preparation Designs for Moderate-sized Class II Composites. J Contemp Dent Pract 2024;25(1):3-9.

Effect of protective coating agents on microleakage and flexural strength of glass ionomer cement and zirconomer. an in vitro study.

PURPOSE: The objective of this study was to assess the microleakage and flexural strength of glass ionomer cement (GIC) and modified GIC (Zirconomer) when coated with protective coating agents such as COAT-IT and G-COAT plus. METHODS: Sixty tooth specimens were grouped into two groups based on the type of restorations (GIC (n = 30) and Zirconomer (n = 30)). The samples were further divided into three subgroups (n = 10) based on the protective coating agent (Petroleum jelly, G-COAT Plus, or COAT IT) applied. This study evaluated the microleakage at the occlusal and cervical margins of class V restoration after being subjected to dye penetration and sectioning. Each specimen was viewed under a 40 × microscope and was given scores based on the depth of dye penetration. They were statistically analyzed using the Kruskal-Wallis test and compared within the groups using the Mann- Whitney Test. In addition, flexural strength was assessed using standardized cuboid (25 × 2 × 2 mm) specimens of restorative materials with and without protective coating agents. The mean flexural strength data of all the subgroups were statistically evaluated using a one-way analysis of variance (ANOVA) and compared within the subgroups using the student t test. RESULTS: A statistically significant difference was found when occlusal margin microleakage scores were evaluated with G-COAT Plus demonstrating the lowest occlusal margin microleakage when applied over GIC restoration. The increasing order of occlusal margin microleakage scores is as follows: GIC with G-COAT Plus, Zirconomer with COAT-IT, GIC with COAT-IT, GIC, Zirconomer with G-COAT Plus, and Zirconomer. However, the cervical margin microleakage scores revealed no significant difference. While flexural strength was found to be highest for the GIC group coated with G-COAT Plus, it was observed that there was a significant improvement in the flexural strength of both GIC and Zirconomer when coated with either of the protective coating agents. CONCLUSION: Within the limitations of this in vitro study, it was observed that the application of protective coating agents can significantly reduce the potential microleakage and improve the flexural strength of the restorative material especially when zirconia-reinforced GIC is the restorative material.

Evaluating the effect of three fissure preparation techniques on microleakage of a colored flowable composite used as a fissure sealant.

Pit and fissure sealants play an essential role in preventive dentistry. This study evaluates the microleakage levels of a new and colored flowable composite applied as a sealant after three preparation techniques. A total of 24 non-carious mandibular permanent molars with deep pits and fissures were included in the study. Pit and fissures were prepared with 37% phosphoric acid, tungsten carbide bur and fissurotomy burs (SS WHITE Dental, New Jersey, USA) using conventional, enameloplasty and fissurotomy techniques. All samples were thermocycled following the placement of Rainbow Flow (PPH CERKAMED Wojciech Pawlowski, Poland) as a sealant and sections were taken after immersion in methylene blue dye. The microleakage levels of the samples were examined under a stereomicroscope (Olympus SZX-7 Olympus SZ-61 Stereo Microscope) at 2.8× magnification to analyze the dye penetration of the flowable composite. The 144 sections were examined and scoring for microleakage was done by examining the dye penetration from the occlusal border to the base of the fissure. Considering all sections regardless of the preparation technique, it was found that 16.6% of the sections have no leakage. Regarding the microleakage scores, the mean score of the conventional group was 1.87 ± 0.98, the mean score of the enameloplasty group was 1.88 ± 1.14, and the mean score of the fissurotomy group was 1.81 ± 1.1. The median scores of the conventional, enameloplasty and fissurotomy groups were 2, 2 and 1.5, respectively. The present study reports no difference between the microleakage level of a colored flowable composite material used as a pit and fissure sealant following three fissure preparation techniques and supports the clinical use of this material.

Orifice barriers to prevent coronal microleakage after root canal treatment: systematic review and meta-analysis.

AIMS: This systematic review aimed to compare the efficiency of orifice barriers in preventing coronal microleakage in vitro. METHODS: Articles published in English, German and Chinese were searched for studies describing microleakage assays for the bacterial penetration of root canal-treated teeth in vitro. The final sample included 18 articles for review and meta-analysis. Risk ratios and confidence intervals were determined for dichotomous variables. Ten publications using bacterial leakage models contributed to the meta-analysis. RESULTS: The addition of orifice barriers to a root canal filling was overall effective, shown by risk ratios (RR) and 95% confidence intervals (CI) demonstrating reduced microleakage with glass ionomer cement (GIC) (RR 0.37, 95% CI 0.26-0.53, P < 0.001), resin-modified GIC (RR 0.32, 95% CI 0.15-0.67, P = 0.01), composite resin (RR 0.54, 95% CI 0.38-0.75, P < 0.001), mineral trioxide aggregate (MTA) (RR 0.25, 95% CI 0.12-0.52, P < 0.001) and Cavit (RR 0.23, 95% CI 0.14-0.39, P < 0.001). There were no significant differences between GIC, resin-modified GIC, composite resin and MTA orifice barriers. CONCLUSIONS: Placement of an orifice barrier over the root canal filling is effective in the prevention of coronal microleakage in vitro. Other parameters may also affect the effectiveness of orifice barriers, including thickness and duration of exposure to the oral environment. © 2023 Australian Dental Association.

Effect of three different conditioning agents on cavosurface microleakage and bond strength of glass ionomer restorations - An in vitro study.

Aim: This study aimed to investigate the conditioning effects of phosphoric acid/5.25% sodium hypochlorite (NaOCl) mixture, 2% chlorhexidine (CHX) digluconate, and 10% polyacrylic acid on cavosurface microleakage and bond strength of glass ionomer (GI) restorations. Materials and Methods: Out of 68 extracted premolars, 34 teeth were selected for microleakage and 34 for bond strength evaluation. The samples were divided into the following four groups. Group 1: pretreatment with 50/50 volume% mixture of 5.25% NaOCl solution and 37% phosphoric acid (H3PO4), Group 2:pretreatment with 2% CHX digluconate, Group 3: pretreatment with 10% polyacrylic acid (positive control), and Group 4: no pretreatment (negative control). All the samples were then restored with glass ionomer cement (GIC). Microleakage was evaluated using a stereomicroscope and rhodamine-B dye penetration test. For bond strength, flat dentin surface was exposed and pretreated as mentioned previously and restored with GIC and was evaluated using universal testing machine. Results: Among all the four groups, Group 1 showed least microleakage and highest bond strength when compared with other groups. Whereas the Group 4 samples which were not pretreated with any of the conditioning agent showed the least shear bond strength with greatest cavosurface microleakage when compared to the groups which were pretreated with the conditioning agents. Conclusions: A combination of 50/50 volume % mixture of 37% H3PO4 and 5.25% NaOCl can be a good choice for surface pretreatment of GI restorations.

Impact of access cavity cleaning on the seal of postendodontic composite restorations in vitro.

AIM: The aim of the study was to investigate the influence of cavity cleaning and conditioning on marginal integrity of directly placed post-endodontic composite class-I-restorations in vitro. METHODOLOGY: A total of 168 fully intact teeth without caries or fillings received pre-endodontic composite restorations (class-II) after their extraction. Occlusal endodontic access-cavities were prepared, and root canals were instrumented and filled with gutta-percha and an epoxy resin-based sealer. Prior to post-endodontic class-I-restoration, access cavities were completely contaminated with sealer, cleaned with alcohol and pre-treated as follows: cleaner only (alcohol), glycine-polishing, Al2 O3 sandblasting, carbide bur (immediate as well as delayed restoration). A positive control (not contaminated with sealer and adhesive used) and negative control (cleaner used but no adhesive) were established. Half of the teeth from each group were subjected to thermocycling and mechanical loading (TCML). Marginal integrity of post-endodontic restoration was evaluated in oro-vestibular or mesio-distal sections after AgNO3 dye penetration (DP) by standardized photomacroscopic imaging and expressed in per cent of margin length along all segments and separately for enamel, dentine and composite, respectively. Results were analysed non-parametrically (α = .05). RESULTS: No restorations or teeth fractured or debonded completely. Without TCML, the median DP of all segments was significantly higher for the negative control compared with all other groups in oro-vestibular cutting direction (53%; p = .002) and in mesio-distal cutting direction (51%; p ≤ .041). The other groups without TCML revealed 16%-24% DP (oro-vestibular) and 12%-24% DP (mesio-distal). With TCML, the median DP in oro-vestibular cutting direction for all segments ranged between 48% and 62% for all groups, a significant difference was only observed between glycine-polishing and carbide bur (p = .041). In mesio-distal cutting direction, the median DP in negative control was 69% with TCML and significantly higher compared with all other groups (p = .002). For all other groups, the median DP of all segments ranged between 28% and 40% with TCML without significant differences. Error rates method (k = 7) revealed a significant influence of TCML in general on penetration of all segments in both oro-vestibular and mesio-distal cutting directions. CONCLUSION: Additional access cavity pre-treatment after alcohol cleaning did not improve the marginal integrity of post-endodontic composite restorations. Thorough cleaning of the access cavity with alcohol seems to assure an acceptable marginal integrity to the tooth and restorative composite.

Sealing Behavior of a New Material Combination in Two-Part Dental Implant Systems: An In Vitro Examination.

PURPOSE: To test a newly introduced implant-abutment material combination against bacterial endotoxin leakage in a human whole blood assay. MATERIALS AND METHODS: Two dental implant systems with internal connections and the following material combinations at the implant-abutment interface (IAI) were used (implant material/abutment material): yttrium-stabilized tetragonal zirconium dioxide (Y-TZP)/polyetherketoneketone (PEKK), and titanium (Ti/Ti). Test implants were inoculated with lipopolysaccharide (LPS) and sealed and submerged in human whole blood. Untreated implants served as the control groups. Changes in gene expression levels of inflammatory markers indicating LPS leakage were assessed after 1, 8, and 24 hours using quantitative real-time polymerase chain reaction. RESULTS: In the Y-TZP/PEKK test group, a significant influence of the implant system (P < .001) on increases in gene expression indicating leakage were detected after 8 hours for TLR-4 and after 24 hours for interleukin 1-ß and nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB), indicating microleakage of LPS at the IAI. In the Ti/Ti test group, differences in gene expression were found only for NF-κB after 8 hours. CONCLUSION: The internal hexalobe IAI of two-piece dental implants fabricated from Y-TZP and PEKK do not prevent LPS molecular microleakage.

Marginal microleakage and modified microtensile bond strength of Activa Bioactive, in comparison with conventional restorative materials.

OBJECTIVES: This study aimed to assess the enamel and dentin marginal microleakage and dentin microtensile bond strength (µTBS) of ACTIVA BioACTIVE Restorative with and without a bonding agent compared with conventional restorative materials. MATERIAL AND METHODS: For enamel and dentin microleakage, Class II boxes were prepared in the mesial (1 mm under the cementoenamel junction) and distal (1 mm above the cementoenamel junction) surfaces of 90 extracted human third molars. The teeth were randomly divided into five groups (n = 18): Group Z (G-Premio Bond + Filtek Z250 XT), Group X (G-Premio Bond + X-tra fil bulk-fill), Group AA (G-Premio Bond + Activa Bioactive restorative), Group A (Activa Bioactive restorative), and Group G (dentin conditioner + Fuji II LC Improve). The teeth were thermocycled, and their microleakage was quantified using the dye penetration test under a stereomicroscope. For dentin µTBS measurement, 12 specimens were fabricated in metal molds (1 × 1 × 12 mm³) for each group mentioned above, and a universal testing machine measured their µTBS. Data were analyzed using one-way analysis of variance (ANOVA), the Kruskal-Wallis test, and multiple comparisons tests. RESULTS: Significant differences were noted among the groups in marginal microleakage and µTBS (p < .001). The highest mean microleakage scores at the enamel and dentin margins were noted in Group A, which had significant differences with other groups (p < .001). The highest µTBS was found in Group X, with significant differences with Group G and Group A (p < .05). The lowest µTBS was noted in Group A, with significant differences with Groups X, Group AA, and Group Z (p < .001). CONCLUSIONS: Activa Bioactive without a bonding agent showed significantly lower µTBS to dentin, and higher microleakage at the enamel and dentin margins. Application of adhesive resin with Activa Bioactive provided a dentine bond strength and marginal seal comparable to other restorative materials.

Microgap and microleakage of a hybrid connection platform-switched implant system in the absence or presence of a silicone-based sealing agent.

The present study aims to characterize, for the first time, the microgap and bacterial microleakage of a platform-switched implant system with hybrid connection, screwed at distinct torque values (manufacturer recommended torque-25 N cm-and a reduced torque-5 N cm-mimicking the long-term functional use), in the absence or presence of a silicon-based sealing agent. Microgap was determined through scanning electron microscopy and bacterial microleakage was evaluated in vitro, upon Enterococcus faecalis colonization of the system. The sealing efficacy was evaluated in the absence or presence of a commercially available silicon-based sealer. The cytotoxicity of the sealer was further addressed in vitro, with a fibroblastic cell line, in accordance with reference standards. A low microgap of the implant system was verified, regardless of the applied torque load-maximal values ranged around 0.25 and 1.25 µm, for 25 and 5 N cm torques, respectively. No bacterial microleakage was reported at 25 N cm, while at 5 N cm, leakage was verified on 38% of the samples. The application of a silicon-based sealer-with an adequate cytocompatible profile-was effective on preventing the bacterial microleakage on the assayed experimental setting. The assayed platform-switched implant system with hybrid connection presented a low interfacial misfit and an effective sealing capability at manufacturer recommended torque. Despite the increased microleakage at low torque conditions, the application of a cytocompatible silicon-based sealing agent restored the sealing effectiveness of the system. The use of a silicon-based sealing agent can assist on the maintenance of the sealing effectiveness even at low torque conditions.

Efficacy of Various Implant Abutment Screw Access Channel Sealing Materials in Preventing Microleakage: A Systematic Review.

The aim of this systematic review is to evaluate the effectiveness of different materials used for sealing dental implant abutment screw access channel (ASAC), in preventing microleakage. As per the searched indexed English literature, this study is the first review of its kind. Indexed English literature published up to February 20, 2021 was systematically searched on relevant electronic databases. The recommendations specified by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) were applied for constructing framework, and reporting the current review. The focused PICO (Participant, Intervention, Comparison, Outcome) question was: "Which material (C) is more effective in sealing (I) implant ASAC (P) in terms of causing minimal microbial leakage (O)". Quality of articles was assessed with modified CONSORT scale for in vitro studies. Five in vitro studies were selected for qualitative analysis after final stage screening. Modified CONSORT scale suggested that out of the 5 selected studies, 1 each was of low and high quality, whereas 3 studies were of moderate quality. Included studies had contrasting results related to the efficacy these materials as sealants in ASAC. Sealing capacity against microleakage should be considered as one of the important criteria while selecting the material to fill implant ASAC. Definitive conclusions asserting superiority of a single material over others are difficult to draw, due to nonhomogeneity in study design of the included papers. More studies should be conducted in the near future to investigate the efficacy of various combination of materials in preventing microleakage.

Quantitative Microbial Leakage Evaluation of Restorative Materials with/without Antibacterial Primer as an Intracoronal Barrier: An Ex Vivo Study.

AIM: Aim of this research was to assess the microbial leakage of restorative materials with/without antibacterial primer as an intracoronal barrier. MATERIALS AND METHODS: Fifty-five extracted single-rooted teeth were included in this study. The canals were cleaned, shaped, and obturated with gutta-percha and AH plus sealer at the established working length. After removing 2 mm of coronal gutta-percha, the teeth were incubated for 24 hours. The teeth were divided into groups according to the materials used as intracoronary orifice barriers as follows: • Group I: Clearfil Protect Bond/Clearfil AP-X • Group II: Xeno IV/Clearfil AP-X • Group III: Chemflex (glass ionomer) • Group IV: Positive control (no barrier) • Group V: Negative control (no barrier and inoculated with sterile broth) Sterile 2 chambers bacterial technique was used to assess the microleakage and Enterococcus faecalis was considered as a microbial marker. The percentage of samples leaked, the time taken for leakage, and the number of colony-forming units (CFUs) in the leaked samples were calculated and analyzed statistically. RESULTS: There was no statistically significant difference found in bacterial penetration among the three investigated materials after 120 days of use as an intracoronal orifice barrier. This study can also infer that the leaked sample from the Clearfil Protect Bond showed the least mean number of CFUs (43 CFUs) followed by Xeno IV (61 CFUs) and glass ionomer cement (GIC) (63 CFUs). CONCLUSION: This study concluded that all three experimental antibacterial primers performed better as intracoronal barrier. However, Clearfil Protect Bond with an antibacterial primer showed promising results as an intracoronal orifice barrier in reducing the number of bacterial leakages. CLINICAL SIGNIFICANCE: The significance of intracoronal orifice barriers in the success of endodontic treatment depends on the ability of the materials to prevent microleakage. This helps clinicians to provide successful antibacterial therapy against endodontic anaerobes.

Comparison of sealing ability of MTA and retroplast as root end filling materials evaluated under a stereomicroscope using rhodamine B dye: An In vitro study.

Aim: The aim of the study was to compare the sealing ability of Mineral Trioxide Aggregate (MTA) and Retroplast as root end filling materials using the Rhodamine B dye penetration method in vitro. Methodology: Forty freshly extracted human single-rooted teeth were randomly divided into two groups of 20 teeth each, and standard root-end cavities were prepared in all teeth. The cavities were filled with MTA and Retroplast in groups 1 and 2, respectively. The specimens were then stored in 1% Rhodamine B dye for a week, following which the dye penetration with all samples was analysed under a stereomicroscope and scored according to Tronstad's criteria. The observations were compared with Chi square test at a 0.220 level of significance. Results: 5% of the samples in both the groups showed no significant leakage. The leakage was deeper with the Retroplast group than with the MTA group; however, there was no statistically significant difference between the two groups. Conclusion: Both MTA and Retroplast are similar in their sealing potential as root-end cavity fillings with Retroplast reporting slightly deeper microleakage than MTA within the limits of the present study.

Bacterial leakage assessment in root canals sealed with AH Plus sealer modified with silver nanoparticles.

BACKGROUND: Successful endodontic therapy requires prevention of bacterial leakage between the root canal filing and root-canal walls. Sealing quality of a root canal filling depends strongly on the sealing ability of the sealer used. The present study aimed to evaluate the bacterial leakage resistance of AH Plus sealer modified with silver nanoparticles. METHODS: Forty sound teeth were obturated using lateral compaction technique except for five teeth as the negative controls. After considering five teeth as the positive controls (filled without sealer), the remaining teeth were assigned to two groups (n = 15) in terms of the sealer used (AH Plus sealer and silver nanoparticle-modified AH Plus). Bacterial leakage was evaluated in saliva using the two-chamber technique in every 24 h. When all the samples in the test groups were contaminated, the study was terminated. The data were analyzed with log-rank statistical test. RESULTS: All samples in both experimental groups were contaminated during the 3-months period of observation. There was no significant difference in contamination time between study groups (P > 0.05). CONCLUSIONS: Silver nanoparticles used in tested concentration did not improve the bacterial leakage resistance of AH Plus sealer.

Assessment of Penetration Depth and Microleakage of Different Pit and Fissure Sealants Using Dye Penetration Method: An In Vitro Study.

AIM AND OBJECTIVE: The aim of this study was to evaluate the depth of penetration as well as the microleakage of three different pit and fissure sealant materials employing the dye penetration method. MATERIALS AND METHODS: Sixty healthy human mandibular premolar teeth without dental caries that were extracted for orthodontic treatment constituted the study samples. These 60 premolar samples were subjected to an equal division (20 in every group) into three groups. Group I: self-adhering flowable composite, group II: flowable nanocomposites, group III: classical pit and fissure sealants. Every sample tooth underwent thermocycling amid 4°C ± 2°C and 60°C ± 2°C for 1,000 cycles. The samples were placed in 1% methylene blue solution for 24 hours to permit diffusion of the dye into probable gaps in between the restoration and the tooth. The teeth were sectioned and evaluated below a stereomicroscope at 10× magnification with image analysis software. RESULTS: Flowable nanocomposites (3.69 ± 0.10) exhibited a slightly greater mean depth of penetration as compared to classical pit and fissure sealants (3.58 ± 0.16) and self-adhering flowable composites (3.51 ± 0.13) in that order. This difference between the three sealants was not significant statistical. Amid the three sealant study groups, the lowest mean marginal microleakage was exhibited by the flowable nanocomposites (1.06 ± 0.03), followed by self-adhering flowable composites (1.98 ± 0.06), and classical pit and fissure sealants (2.74 ± 0.11). Analysis of variance revealed statistically significant differences among the three sealants that were studied. CONCLUSION: This study concludes that flowable nanocomposites depicted enhanced penetration and reduced marginal leakage as compared to the self-adhering flowable composites and classical pit and fissure sealants. CLINICAL SIGNIFICANCE: An efficient approach to preventing dental caries on the occlusal surfaces of teeth is the use of pit and fissure sealants. The efficiency of sealants chiefly depends on the morphological characteristics of the fissures and properties of dental materials used.

Comparing Bacterial Leakage of Three Intraorifice Barrier Sealing Materials against Enterococcus faecalis and Proteus vulgaris.

AIM: The purpose of this in vitro study was to evaluate the intraorifice sealing ability of light-cured glass-ionomer cement (LC-GIC), Tetric N-Flow, and ProRoot mineral trioxide aggregate (MTA) against Enterococcus faecalis and Proteus vulgaris. MATERIALS AND METHODS: Crowns of the eighty human mandibular teeth were decapitated. Working length determination was performed, after which cleaning and shaping were carried out. A uniform orifice diameter of 1.3 mm, at its widest point, was made. Once instrumentation was completed, the canals were irrigated and then obturated. A heat carrier was used to remove gutta-percha to the depth of 3.5 mm. Samples were then divided into a control group (Group 1) with no barrier, and three groups, namely, Group 2, Group 3, and Group 4, were restored with the LC-GIC, Tetric N-Flow, and ProRoot MTA, respectively. The groups were further subdivided into Subgroup A for checking bacterial leakage against E. faecalis and Subgroup B, against P. vulgaris. All samples were subjected to the bacterial leakage test and observed daily for the appearance of turbidity after which statistical analysis was performed. RESULTS: Group 1 showed leakage in, as early as, 3 days. The longest time for the turbidity to appear was shown by Group 4 with an average of 31 days. The mean number of days for turbidity to appear in Group 2 and Group 3 was 23 and 24 days, respectively. Group 4 showed the best intraorifice sealing ability with a significant difference. CONCLUSION: The teeth with an intraorifice coronal seal had better protection against microbial leakage. Among all materials used, the ProRoot MTA showed the best intraorifice sealing ability. CLINICAL SIGNIFICANCE: Use of the ProRoot MTA promises long-term results in the endodontically treated teeth as compared with other materials.

Intelligent pH-responsive dental sealants to prevent long-term microleakage.

OBJECTIVES: Microleakage is a determinant factor of failures in sealant application. In this study, DMAEM (dodecylmethylaminoethyl methacrylate), a pH-responsive antibacterial agent, was incorporated into resin-based sealant for the first time. The objectives of this study were to: (1) investigate the long-term performance of DMAEM-modified sealants against oral microbial-aging; and (2) investigate the long-term preventive effect of DMAEM-modified sealants on microleakage. METHODS: Depth-of-cure and cytotoxicity of DMAEM-modified sealants were measured. Then, an aging model using biofilm derived from the saliva of high caries experience children was conducted. After aging, microhardness and surface roughness were measured. Biofilm activity, lactic acid production and exopolysaccharide (EPS) production were measured. 16S rRNA gene sequencing were also performed. The effects of DMAEM on microleakage were tested using an in vitro microleakage assessment. RESULTS: The addition of DMAEM with a mass fraction of 2.5-10% did not affect depth-of-cure values and cytotoxicity of sealants. Adding 2.5-10% DMAEM did not affect the surface roughness and microhardness after aging. Compared to control, adding 2.5-10% DMAEM reduced biofilm metabolic activity by more than 80%. The lactic acid production and EPS production were reduced by 50% in DMAEM groups. DMAEM-modified sealants maintained the microbial diversity of biofilm after aging, they also inhibited the growth of lactobacillus. The 5% and 10% DMAEM groups exhibited a significant reduction in microleakage compared to control. SIGNIFICANCE: The long-term antibacterial activities against oral microbial-aging and the long-term microecosystem-regulating capabilities enabled DMAEM-modified sealant to prevent microleakage in sealant application and thus prevent dental caries.

Does Cavity Disinfectant Affect Sealing Ability of Universal Self-etch Adhesive?

AIM: The purpose of this study was to evaluate 2% chlorhexidine disinfectant (CHX), chitosan, and octenidine dihydrochloride (as cavity disinfectants) on microleakage in cavities restored with universal self-etch adhesive. MATERIALS AND METHODS: Eighty extracted human permanent premolars were selected. Class V cavities were prepared on the facial surface of each tooth. The teeth were then divided into four groups of 20 teeth each. For the control group after cavity preparation, no disinfectant was applied. The other 3 groups were treated with 0.1% chitosan, 2% CHX, and 0.1% octenidine dihydrochloride (OCT). All the groups were restored with universal adhesive followed by composite resin. The teeth were then immersed in 1% methylene blue dye and were sectioned buccolingually. Microleakage was checked under a stereomicroscope on both occlusal and gingival margins. RESULT: Among all the groups chitosan-treated cavities showed the least microleakage. Chlorhexidine treated cavities showed less leakage as compared to control, OCT group at both the margins. CONCLUSION: Chitosan as a cavity disinfectant improves the sealing ability of the self-etch adhesive. Furthermore, in vivo studies need to be conducted to examine the interaction and long-term effect of chitosan with the other self-etch adhesive systems. CLINICAL SIGNIFICANCE: Chitosan a natural polysaccharide can be used as a cavity disinfectant as it improves the sealing ability of self-etch adhesive.

Effects of different antibacterial disinfectants on microleakage of bulk-fill composite bonded to different tooth structures.

BACKGROUND: This in-vitro study aimed to investigate the effect of two different antibacterial disinfectants on the microleakage performance of newly developed bulk-fill composite, bonded to different tooth structures. METHODS: Class V cavities were prepared in 30 sound premolar teeth, with enamel occlusal margins (OM) and dentin cervical margins (CM). Two disinfectants, 2% chlorhexidine gluconate (CHX) and Listerine Miswak (ListM), were used. Teeth were divided into three groups (n = 10): G1, Control; G2, CHX; and G3, ListM. Disinfectants were applied to the cavity preparation walls after they were etched with 35% phosphoric acid. The Single Bond Universal adhesive system was then used, and teeth were restored with Filtek One Bulk Fill composite. Samples were examined, after thermocycling aging, by stereomicroscopy for the evaluation of marginal dye penetration. RESULTS: The highest mean microleakage score was reported in the CM of G1 (2.60 ± 1.174), which was significant compared with that of G2 only (p = 0.02). OM in G1 showed no microleakage, with no significant differences found among groups (χ2 = 1.39, p = 0.50). No significant differences were reported between G2 and G3 (p = 0.45 OM; p = 0.17 CM). CONCLUSIONS: Cavity pretreatment with CHX is not significantly different to pretreatment with CHX. In contrast, CHX improved the cervical marginal seal as compare to the control group (G1).

Microleakage of pit and fissure sealings placed after enamel conditioning with phosphoric acid or with self-etching primers/adhesives.

BACKGROUND: It is still not fully understood what pretreatment is best for achieving maximum tightness for pit and fissure sealings (PFS). AIM: This study investigated microleakage of PFS placed after etching with phosphoric acid or after the application of self-etching primers/adhesives (SEPA). DESIGN: 131 third molars were assigned to ten groups. In Hel-P, Helioseal® was applied after phosphoric acid etching. In the other groups, SEPA were used (Dyr-AP: Adper™ Prompt™ L-Pop™, Dyract® Seal; Bea: BeautiSealant Primer and Paste; Hel-Exp: Experimental primer, Helioseal®; Hel-Cl: Clearfil™ SE Bond1 , Helioseal®). Specimens were stored in distilled water at 37°C (28 days), followed by 3500 thermocycles and staining with 5% methylene blue (M) or 5% silver nitrate (S). After methylene blue staining and sectioning, microleakage was assessed light microscopically. During silver nitrate staining, specimens were dissolved by 32% HCl and remaining PFS were evaluated under a SEM. RESULTS: Tightness, percentage of penetrated area, and maximum dye penetration were best for Hel-P and Hel-Cl (p < 0.05). CONCLUSIONS: Phosphoric acid etching of enamel and Clearfil™ SE Bond resulted in the best sealing quality. Methylene blue staining allowed the evaluation of more criteria (fissure shape, voids, sealant penetration depth) compared to silver nitrate.

[Effect of different pretreatment methods on dentin microleakage and bonding effect in caries].

PURPOSE：To evaluate the effect of different pretreatment methods on dentin microleakage and bonding effect of caries, so as to provide reference for clinical practice. METHODS: Sixty isolated caries were collected from Department of Oral and Maxillofacial Surgery, Affiliated Stomatological Hospital of Nanchang University from January 2020 to December 2020, and 120 dental samples were obtained by grinding them into two halves along the long axis of the precursor teeth. According to different pretreatment methods, they were divided into group A (2%NaClO), group B (2% chlorhexidine) and group C (75% ethanol). The bond strength, microtensile test and microleakage of the three groups of teeth were compared. SPSS 24.0 software package was used for statistical analysis of the data. RESULTS: The bond strength of the three groups from high to low was group A, group B and group C(P＜0.05); the fracture type of the three groups was compared, mixed damage of group A was lower than that of group B and group C； microleakage of the three groups was compared, and microleakage of group A was better than that of group B and group C(P＜0.05). CONCLUSIONS: Pre-treatment with 2%NaClO can reduce dentin microleakage and significantly improve the bonding strength of teeth, which is conducive to the promotion and application in the treatment of dental diseases.