Flowable Liner Research Articles

Effect of Different Flowable Liners under Packable Composite on the Cuspal Deflection in Maxillary Premolar Teeth: An In Vitro Study

Effect of Different Flowable Liners under Packable Composite on the Cuspal Deflection in Maxillary Premolar Teeth: An In Vitro Study

Bulk-Fill Ormocer versus Methacrylate-Based Resin Composite Restorative Systems: The Effect of Flowable Lining on Two-Year Clinical Performance in Class II Cavities

Abstract Objective The aim of this study was to assess and compare the impact of bulk-fill flowable resin composite liners (BFFL) on the 2-year clinical performance of bulk-fill ormocer (BORC) in comparison to methacrylate-based resin composites (BMRC) in Class II cavities. Materials and Methods Thirty participants, each aged between 18 and 30 years, were included in the study, each presenting four class II cavities. A total of 120 restorations were placed, with participants randomly assigned to one of four restorative systems through a blind drawing: Admira Fusion X-Tra (AFX) alone, AFX after lining with Admira Fusion Xtra-Base (AFB), X-Tra Fill (XF) for complete cavity filling, and XF after lining with Xtra-Base (XB). The universal adhesive system (Futura U bond Voco, Germany) was consistently applied for all restoration techniques using selective enamel etching. A single operator, following the manufacturer's instructions for each material, performed all restorations, and finishing/polishing occurred immediately after placement. Clinical evaluation, based on World Dental Federation (FDI) criteria, was conducted by two blinded examiners at baseline (7 days) and at 6, 12, and 24 months postoperatively. Results The chi-squared test was used to compare the four applied restorative systems within each follow-up period, while the marginal homogeneity test was employed to assess changes over time. No statistically significant differences were observed among the four restorative systems at any evaluation period. Conclusions After 2 years, the clinical performance of BFFL or complete bulk-fill technique remained similar, regardless of the material composition.

Preheating and "snow-plow" composite application technique affect double bond conversion but not bond strength to dentine.

To measure degree of conversion (DC) of a flowable composite, microtensile bond strength (MTBS) to dentine in the snow-plow technique with/without preheating and temperature in the preheated composite. For DC, snow-plow specimens of Filtek Ultimate Flowable (Flow) and Filtek Bulk Fill (Bulk) (3M) were prepared by light-curing composites simultaneously in standardized molds while in control groups light-curing was separate. DC of Flow was measured using micro-Raman spectroscopy. For MTBS, specimens were prepared on dentine of human extracted molars by simultaneous (snow-plow) or separate (control) light-curing. MTBS was measured using a universal testing machine after 24 h and 6 months. Data were analyzed using ANOVA with Tukey's post hoc (α = 0.05). Increased curing time significantly increased DC in snow-plow from 13.4% ± 11.6% (10 s) to 31.8% ± 4.4% (40 s) albeit significantly lower than controls (p < 0.05). Preheated Bulk improved conversion in snow-plow (44.3% ± 1.7%) and control (50.5% ± 2.6%) (p < 0.05). No significant differences occurred in MTBS between groups (p > 0.05). MTBS values ranged between 66.7 ± 8.4 MPa (snow-plow group_21°C_baseline) and 54.1 ± 15.8 MPa (control_21°C_long-term). Temperature in the preheated Bulk dropped to ~38°C after 30 s. Snow-plow technique, irrespective of preheating, resulted in lower DC of Flow than separate light-curing of composite increments. Snow-plow, irrespective of preheating, resulted in similar initial and long-term MTBS to dentine. Clinicians with preference for flowable composite liners in Class II restorations should be aware that the snow-plow technique of simultaneous light-curing of flowable and bulk-fill composite increments affects monomer-to-polymer conversion, albeit no effect on immediate, and long-term bonding to dentine was detected. Preheating sculptable bulk-fill composite improves conversion of the flowable liner in the snow-plow technique but has no detectable effect on bond strength to dentine.

Investigating the impact of flowable composite liner on the fracture strength and microleakage of large composite resin restorations of primary anterior teeth.

To investigate the effect of pre-cured and co-cured flowable composite liner on fracture strength and microleakage of primary anterior teeth with extended composite resin restorations. In the current in vitro experimental study, the crowns of 54 extracted primary canine teeth were cut 1mm above the CEJ, and a pulpectomy procedure was performed. The samples were randomly divided into three groups to restore the coronal part up to 4mm above the CEJ. In group 1, the samples were built up with Filtek Z250 packable composite resin. In group 2 (pre-cure), first, 1mm of Filtek Z350 XT flowable liner was applied to the sample, and after curing, the restoration process continued using packable composite resin. In group 3 (co-cure), the flowable composite liner was cured while the first layer of packable composite resin was applied; then, the same restorative procedure similar to the other groups was followed. The samples' cross-sectional area in the fracture strength test was calculated by AutoCAD software. Subsequently, the samples were subjected to a force in a universal testing machine. The samples related to the microleakage experiment were cut vertically, and then, the dye penetration percentage (10% methylene blue) was measured under a stereomicroscope. ANOVA was used to analyze the data. Mean fracture strength in group 2 was significantly higher than in group 1 (P = 0.016). The microleakage mean in group 3 was significantly lower than in groups 1 (P = 0.000) and 2 (P = 0.026). The flowable composite liner and its relevant separate curing increased the fracture strength of composite resin restorations. However, less microleakage was reported in the group where the liner was applied as a co-cure.

Five-year clinical performance of two fluoride-releasing giomer resin materials in occlusal restorations.

To evaluate and compare the clinical performance of two nano-hybrid giomer restorative composite materials after 5 years. Forty-four pairs of restorations (total n=88) of a flowable giomer (Beautifil Flow Plus F00; Shofu Inc., Kyoto, Japan) and a conventional nano-hybrid giomer restorative material (Beautifil II; Shofu Inc.) were placed in Class I cavities after the application of a dentin adhesive (FL-Bond II; Shofu Inc.) and a flowable liner (Beautifil Flow Plus F03; Shofu Inc). After 5 years, 32 pairs of restorations were assessed using the modified United States Public Health Service criteria. Both tested materials were compared using Fisher's exact test and each tested clinical criterion for each material was analyzed separately with respect to different follow-up periods using Friedman's test (a=0.05). None of the restorations showed complete retention loss, post-operative sensitivity, secondary caries or color change. There were no significant changes to any of the clinical criteria for each material during the 5-year evaluation period (p > 0.05) and no significant differences between the two materials in all clinical parameters after 5 years (p > 0.05). Five-year clinical performance of both two nano-hybrid giomer restorative materials was comparably acceptable and not significantly different for any of the parameters evaluated. Nano-hybrid giomer-based materials are clinically acceptable for the restoration of occlusal cavities as they demonstrate excellent performance after 5 years.

Effects of application method on shrinkage vectors and volumetric shrinkage of bulk-fill composites in class-II restorations

ObjectivesUpon initial proximal wall construction, the favorable C-factor of class-II cavities may become unfavorable. This study investigated the application method on bulk-fill resin composite polymerization shrinkage. MethodsOccluso-proximal class-II cavities were prepared in 40 molars and bonded with a self-etch adhesive (Adhese Universal). The study groups varied according to the resin composite application: group-1: bulk application, Tetric EvoCeram Bulk Fill (TBF); group-2: proximal wall construction (TBF) and occlusal cavity filling (TBF); group-3: thin flowable liner layer, Tetric EvoFlow Bulk Fill (TEF) and bulk filling (TBF); group-4: flowable liner (TEF), proximal wall (TBF), occlusal cavity (TBF); and group-5: bulk application, SDR (3 mm) and capping layer (TBF, 1 mm). Each resin composite increment was scanned twice using micro-CT (uncured, cured 40 s) at a resolution of 16 µm. Shrinkage vectors and volumetric polymerization shrinkage were evaluated and statistically analyzed (one-way ANOVA). SEM images were used to investigate the tooth-restoration interface. ResultsShrinkage vectors differed significantly among the groups and were greatest in gp5-fl/SDR (47.6 µm), followed by gp1-TBF (23.8 µm) and least in gp5-fl/SDR+TBF (11.1 µm). Volumetric shrinkage varied significantly with the use of SDR (gp5-fl/SDR: 2.6%) and TEF (gp4-fl/TEF: 2.5%) to TBF (gp4-fl/TEF+wl/TBF: 0.6%) in the incremental application. SignificanceBuilding a proximal resin composite wall yielded smaller shrinkage vectors than the bulk application. Applying a thin flowable liner decreased the shrinkage vectors, even more when building a proximal wall. A thin flowable liner is recommended when building a proximal resin composite wall.

White-opaque flowable composite liner as a depth marker in composite restorations prevents tooth substance loss in filling removal: a randomized double-blinded in vitro study

ObjectivesRemoval of esthetic restorations leads to loss of tooth structure and the extent of the loss is difficult to estimate due to exact-shade matching. This randomized double-blinded in vitro study aimed examining the influence of a white-opaque flowable composite depth marker as an optical removal aid for tooth substance preservation and shortened restoration removal time.Materials and methodsClass II cavities (n = 100) in extracted healthy mandibular molars (n = 50, two runs) were prepared, filled, and the restoration removed. Tooth weight and volume (before and after) and removal time were measured and remnants visually documented. An optimal tooth shade-matched flowable composite liner was used as control.ResultsTooth structure loss was significantly lower using a white-opaque liner. Mean values for volume/weight loss were 0.037 ± 0.030 g and 0.016 ± 0.005 cm3 (p < 0.01) for white-opaque liner; 0.067 ± 0.000 g and 0.028 ± 0.003 cm3 (p < 0.01) for tooth-colored composite. Removal time and number of pulp chamber perforations showed no significant differences (p = 0.80).ConclusionsWithin the limitations of this randomized double-blinded in vitro study, the use of a white-opaque flowable liner as a depth marker may provide the practitioner a visual aid in the replacement of a composite restoration and may protect against tooth structure loss.Clinical relevanceWhen restoration replacement is indicated, removal of esthetic restorations often causes tooth structure loss due to difficult optical color matching. Using a white-opaque flowable liner as a depth marker clinically aids in restoration removal and protects against tooth structure loss.

Effects of flowable liners on the shrinkage vectors of bulk-fill composites

ObjectivesThis investigation evaluated the effect of flowable liners beneath a composite restoration applied via different methods on the pattern of shrinkage vectors.MethodsForty molars were divided into five groups (n = 8), and cylindrical cavities were prepared and bonded with a self-etch adhesive (AdheSe). Tetric EvoCeram Bulk Fill (TBF) was used as the filling material in all cavities. The flowable liners Tetric EvoFlow Bulk Fill (TEF) and SDR were used to line the cavity floor. In gp1-TBF, the flowable composite was not used. TEF was applied in a thin layer in gp2-fl/TEF + TBF and gp3-fl/TEF + TBFincremental. Two flowable composites with a layer thickness of 2 mm were compared in gp4-fl/TEF + TBF and gp5-fl/SDR + TBF. TEF and SDR were mixed with radiolucent glass beads, while air bubbles inherently present in TBF served as markers. Each material application was scanned twice by micro-computed tomography before and after light curing. Scans were subjected to image segmentation for calculation of the shrinkage vectors.ResultsThe absence of a flowable liner resulted in the greatest shrinkage vectors. A thin flowable liner (gp2-fl/TEF + TBFbulk) resulted in larger overall shrinkage vectors for the whole restoration than a thick flowable liner (gp4-fl/TEF + TBF). A thin flowable liner and incremental application (gp3-fl/TEF + TBFincremental) yielded the smallest shrinkage vectors. SDR yielded slightly smaller shrinkage vectors for the whole restoration than that observed in gp4-fl/TEF + TBF.ConclusionsThick flowable liner layers had a more pronounced stress-relieving effect than thin layers regardless of the flowable liner type.Clinical relevanceIt is recommended to apply a flowable liner (thin or thick) beneath bulk-fill composites, preferably incrementally.

Three-year Clinical Performance of Two Giomer Restorative Materials in Restorations.

The clinical performance of both conventional and flowable giomer restorative materials was particularly good in Class I restorations after three years of service. This study evaluated and compared the clinical performance of a flowable and a conventional giomer restorative material after three years. Forty-four pairs of restorations (total n=88) were placed in Class I cavities with either a flowable giomer (Beautifil Flow Plus F00; Shofu Inc, Kyoto, Japan) or a conventional giomer restorative material (Beautifil II; Shofu Inc) after the application of a dentin adhesive (FL-Bond II; Shofu Inc) and a flowable liner (Beautifil Flow Plus F03; Shofu Inc). After 3 years, 39 pairs of restorations were evaluated with the modified United States Public Health Service criteria, and digital color photographs of restorations were taken at each patient visit. The evaluation parameters were as follows: color match, marginal integrity, marginal discoloration, retention, secondary caries formation, anatomic form, surface texture, and postoperative sensitivity. Evaluations were recorded as a clinically ideal situation (Alpha), a clinically acceptable situation (Bravo), or a clinically unacceptable situation (Charlie). Data were analyzed with Fisher's exact and McNemar tests (α=0.05).None of the restorations showed retention loss, postoperative sensitivity, secondary caries, or color change. The performance of Beautifil II in terms of marginal integrity, marginal discoloration, and surface anatomic form was significantly lower at the 36-month follow-up than at baseline (p=0.007). There were no significant differences between the baseline and 36-month follow-up scores for the other criteria for Beautifil II (p>0.05). No differences were found between the baseline and the 36-month follow-up scores for any of the criteria for Beautifil Flow Plus F00 (p>0.05). No statistically significant difference in overall clinical performance was found between the 2 materials after 36 months (p>0.05).The three-year clinical performance of both restorative materials (Beautifil Flow Plus F00 and Beautifil II) was very good and not significantly different for any of the parameters evaluated.

Influence of flowable composite liner on the microleakage of posterior packable resin Composites - An in vitro study

Introduction: The aim of this study was to investigate the influence of flowable composite intermediary liner on the microleakage between the tooth tissue and the packable composite resin. Materials and Methods: Forty mandibular molars, each prepared with two class II cavities were randomly divided in two groups: In group A one side was restored with Solitaire (KULZER); the other side was lined with Charisma flow (KULZER) and then restored with Solitaire. In group B one side was restored with Filtek p60 (3M); the other side was lined with Filtek flow (3M) and then restored with Filtek p60. Teeth were then thermocycled for 1000 cycle at 5o and 55o and immersed in a solution of 0.5% basic fuschin dye for 24 hours. Embedded specimens were sectioned longitudinally. Cervical and occlusal microleakage was measured by the extent of dye penetration. Results: Statistically in both groups, microleakge was more in the cavities that were not lined with flowable composites and the cervical margins showed more amount of microleakage as compared to occlusal margins with and without liner. Overall there was no significant difference in the amount of leakage among the two companies at cervical and occlusal margins, with and without flowable liner. Conclusion: Microleakge was more in the cavities that were not lined with flowable composites as compared to cavities lined with flowable composite both in occlusal and cervical margins. The cervical margins showed more amount of microleakage as compared to occlusal margins with and without liner. Keyword: Microleakge, Flowable composite, Packable composite.

Probing the hierarchy of evidence to identify the best strategy for placing class II dental composite restorations using current materials.

The objective of this review is to present a synopsis of the existing clinical and in vitro evidence regarding placement of direct class II restorations with dental composites of varying viscosities, focusing on the marginal integrity achievable. The literature on class II composites placed with various techniques was searched through PubMed, Scopus, and the citations of identified articles, focusing on aspects related to adaptation and clinical performance. Studies comparing layering of conventional composite to layering with a flowable liner, including the "snow plow technique," use of warmed composite, flowable bulk-fill liners with a conventional composite capping layer, and bulk-fill restorative in a single or incremental fill (including placement with sonic energy and dual-curing) CONCLUSIONS: In vitro and clinical evidence does not support any one specific method or material type for achieving optimal performance when restoring class II cavity preparations with current dental composites. Although there are many available placement methods and types of composite materials on the market for use in class II restorations, the reasonable success presented in the clinical and laboratory literature for the various approaches suggests that the most important factor for achieving success is likely careful and proper placement and light-curing technique, independent of the approach.

Class II resin composite restorations\u2014tunnel vs. box-only in vitro and in vivo

PurposeIn a combined in vitro/in vivo approach, tunnel vs. box-only resin composite restorations should be evaluated using thermomechanical loading (TML) in vitro and a restrospective clinical trial in vivo.Materials and methodsFor the in vitro part, box-only and tunnel cavities were prepared in 32 extracted human third molars under simulated intraoral conditions in a phantom head. Specimens were randomly assigned to four groups (n = 8; 16 box-only/16 tunnel) and received bonded resin composite restorations with Amelogen Plus (box A/tunnel A) or lining with Ultraseal and Amelogen plus (box B/tunnel B) both bonded using PQ1 (all Ultradent). Specimens were subjected to a standardized aging protocol, 1-year water storage (WS) followed by TML (100,000 × 50 N; 2500 × + 5/+ 55 °C). Initially and after aging, marginal qualities were evaluated using replicas at × 200 magnification (SEM). For the corresponding in vivo observational study, 229 patients received 673 proximal resin composite restorations. From 371 tunnel restorations, 205 cavities were filled without flowable lining (tunnel A), and 166 tunnels were restored using UltraSeal as lining (tunnel B). A total of 302 teeth received conventional box-only fillings. Restorations were examined according to modified USPHS criteria during routine recalls up to 5 years of clinical service.ResultsIn vitro, all initial results showed 100% gap-free margins when a flowable lining was used. Tunnels without lining exhibited some proximal shortcomings already before TML and even more pronounced after TML (p < 0.05). After TML, percentages of gap-free margins dropped to 87–90% in enamel with lining and 70–79% without lining (p < 0.05). In vivo, annual failure rates for box-only were 2.2%, for tunnel A 6.1%, and for tunnel B 1.8%, respectively (p < 0.05). Tunnels had significantly more sufficient proximal contact points than box-only restorations (p < 0.05). Flowable lining was highly beneficial for clinical outcome of tunnel-restorations (p < 0.05).ConclusionsWith a flowable lining, tunnel restorations proved to be a good alternative to box-only resin composite restorations.Clinical relevanceClass II tunnel restorations showed to be a viable alternative for box-only restorations, however, only when flowable resin composite was used as adaptation promotor for areas being difficult to access.

The effect of flowable composite lining and dentin location on microtensile bond strength and internal fracture formation.

The objective of this study was to determine the effect of flowable composite lining and dentin location on internal dentin fracture formation in the microtensile bond strength (MTBS) test using swept-source optical coherence tomography (SS-OCT). MTBS test beams (1.0×1.0 mm) were prepared from human superficial and deep dentin, which was bonded with a self-etch adhesive (Clearfil SE Bond) and hybrid composite resin (Clearfil AP-X), with or without flowable lining (Clearfil Majesty ES-Flow). We tested 4 groups according to placement technique (with vs. without flowable liner) and dentin (superficial vs. deep) locations. Cross-sectional 2D images of the bonded interface were obtained before and after the MTBS test. Internal dentin fracture after MTBT was observed as a bright zone in SS-OCT. Flowable lining significantly reduced internal fracture formation in dentin (p<0.05). Dentin location significantly influenced MTBS (p<0.05), and this was reduced by flowable lining usage.

Influence of Shrinkage and Viscosity of Flowable Composite Liners on Cervical Microleakage of Class II Restorations: A Micro-CT Analysis.

This study determined the influence of shrinkage and viscosity of flowable composite liners on the cervical microleakage of Class II restorations using micro-CT. Seven composites of varying viscosities were selected and included five giomers (Shofu Beautifil II [BF], Flow Plus F00 and F03 [F00 and F03], Flow F02 and F10 [F02 and F10]) and 2 nano-filled composites (3M-ESPE Filtek Z350 [Z350] and Filtek Z350 Flowable [Z350F]). Polymerization shrinkage (n=7) was assessed with the Acuvol volumetric shrinkage analyzer while complex viscosity was determined with the advanced rheometric expansion system at 25°C. Standardized Class II restorations incorporating 1-mm horizontal layers of different flowable liners and 3-mm oblique layers of BF or Z350 were subjected to a silver nitrate test for 24 hours and examined using micro-CT. Microleakage was determined at 0.1-mm intervals from the buccal to lingual surfaces providing 30 sites per specimen and scored accordingly. Statistical analysis was performed with the one-way ANOVA, Kruskal-Wallis test, and Spearman's rho correlation at a significance level of p<0.05. Mean volumetric shrinkage ranged from 5.33±0.17% to 2.35±0.02% for F02 to Z350, respectively. The flowable materials had significantly higher shrinkage than did their sculptable counterparts (BF and Z350). Complex viscosities ranged from 9.65 to 4.20 (Z350 and F10, respectively) at a frequency of 10 rad/s and from 8.16 to 3.28 (Z350 and F03, respectively) for 100 rad/s. Giomer restorations had significantly less leakage than did those restored with nano-filled composites. No microleakage was observed with restorations lined with F02 or F10. The use of flowable liners reduced cervical microleakage of Class II restorations. Interfacial integrity of Class II restorations was significantly correlated with liner viscosity, filler volume, and shrinkage.

Cross-sectional imaging of tooth bonding interface after thermal stresses and mechanical fracture.

This study determined the influence of thermocycling (TC) and flowable composite on microtensile bond strength (MTBS), crack formation and mechanical properties of the bonding interface using swept-source optical coherence tomography (SS-OCT) and nanoindentation. MTBS test beams prepared from human dentin bonded with self-etch adhesive and hybrid composite with or without flowable lining were aged for either 0 or 10,000 thermocycles, resulting in 4 groups of specimens according to the placement technique and TC (n=10). 2D images were obtained before and after MTBS test to detect crack at interface using SS-OCT. Hardness across resin-dentin bonding area were measured using nanoindentation. Two-way ANOVA showed that flowable lining significantly increased MTBS (p<0.05). TC significantly increased crack percentage in composite while there was no significant difference in dentin crack. Moreover, TC significantly affected the hardness of dentin and resin composites (p<0.05). SS-OCT is effective in detecting internal fracture in substrate.

To evaluate and compare the effect of different light-curing modes and different liners on cuspal deflection in premolar teeth restored with bulk filled or incrementally filled composite measured at different time intervals.

Aim:The aim of this study is to evaluate and to compare the effect of different light-curing modes and different liners on cuspal deflection in premolar teeth restored with bulk filled or incrementally filled composite measured at different time intervals.Materials and Methods:The study was divided into two parts (Part 1-different curing modes, Part 2-different liner) each with sixty extracted human upper premolar teeth with standardized large mesio-occlusal-distal cavities prepared. Each part was divided into two groups according to the composite used (Group A-Filtek Z350 XT, Group B-Sonic fill). Each group was then divided into three subgroups according to the light-curing modes (soft-start, pulse, and continuous curing mode) and liner (Filtek Z350 XT Flowable, Vitremer) used. The cuspal deflection was then measured with a digital micrometer gauge and subjected to statistically analysis using analysis of variance and Tukey's post hoc test.Results:Sonic fill composite, resin-modified glass ionomer cement (RMGIC) liner and curing with soft-start/pulse curing mode had significantly lower cuspal deflection compared to Filtek Z350 XT, flowable liner, and continuous curing mode, respectively.Conclusion:Sonic fill composite, RMGIC liner under the restorations and composites cured with soft start/pulse curing mode resulted in reduced cuspal deflection.

Comparative evaluation of the bond strength of posterior composite with different cavity configurations and different liners using a two-step etch and rinse adhesive system: In vitro study.

Introduction:Conventional Class II cavity preparations used for restoring small lesions with amalgam may be inappropriate for composite resin restorations due to the extensive cavity form, large occlusal contact area, and thin or missing margins of the tooth. Cavity preparation in the proximal areas as per the precepts of Clark is a conservative method of caries excavation and tooth preparation.Materials and Methods:Conventional Class II and Clark's Class II cavities were prepared on the mesial surfaces of 60 molars. All cavities were given a standard buccolingual width of 2 mm, an occlusogingival height of approximately 3.5 mm and an axial depth of 1.5 mm. These were then restored using flowable composites or resin-modified glass-ionomer cement liners and nanohybrid composites. The compressive bond strength was tested with a universal testing machine.Results:The compressive bond strength was the highest for Clarks Class II cavity preparation with a lining of flowable composites. Conventional Box only Class II cavities restored with flowable liners showed the next best result.Conclusion:Clark's class II cavity preparation can be used as efficiently as the conventional Class II box preparation with the advantage of preserving more tooth structure, more precise tooth preparation, good bond strength and better esthetics.

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

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. 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 2mm 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 4mm 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. 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). Bulk-filling technique showed clinically acceptable performance comparable to the incremental technique. 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.

Interfacial Adaptation of Composite Restorations Before and After Light Curing: Effects of Adhesive and Filling Technique.

To investigate the effects of placement technique and adhesive material on adaptation of composites before and after light curing. Cylindrical cavities (3 mm diameter, 1.7 mm depth) in extracted human molars were restored in 6 groups (n=5) using 2 adhesives--two-step self-etching Clearfil SE Bond 2 (SE2) and all-in-one Clearfil Tri-S Bond Plus (TSP) (Kuraray Noritake Dental)--and 2 composites--Estelite Sigma Quick (ESQ) and Estelite Flow Quick (FLQ) (Tokuyama Dental)--placed with three different techniques: ESQ bulk placed, FLQ lining followed by ESQ and FLQ bulk placed. Specimens were scanned twice using swept-source optical coherence tomography (SS-OCT) before and after photopolymerization of the composite. Gap formation during polymerization or the difference in floor interface (DFI%) and final unsealed interface (USI%) were measured by image coregistration and subtraction on 6 diametrical planes across each scan. Two-way ANOVA suggested that both factors (adhesive and filling technique) and their interaction were significant (p<0.001). SE2 showed significantly lower DFI% than did TSP when the composites were placed in bulk, but no difference was found when flowable lining was applied (p<0.05). Within TSP, all filling techniques were significantly different and the lining group showed the lowest values, followed by ESQ-bulk. Overall, SE2 always showed lower UFI% than did TSP, while there was no difference among different techniques within SE2. SS-OCT is a unique method to observe the pre-existing interfacial defects and gaps developed during polymerization, which were found to depend on both placement technique and applied adhesive.

Evaluation of Gingival Microleakage in Class II Composite Restorations with Different Lining Techniques: An In Vitro Study.

Aim. To compare the microleakage in class II composite restorations without a liner/with resin modified glass ionomer and flowable composite liner. Method. Forty standardized MO cavities were prepared on human permanent mandibular molars extracted for periodontal reasons and then divided into 4 groups of ten specimens. The cavity preparations were etched, rinsed, blot dried, and light cured and Adper Single Bond 2 is applied. Group 1 is restored with Filtek P60 packable composite in 2 mm oblique increments. Group 2 is precure group where 1 mm Filtek Z350 flowable liner is applied and light cured for 20 sec. Group 3 is the same as Group 2, but the liner was cocured with packable composite. In Group 4, 1 mm RMGIC, Fuji Lining LC is applied and cured for 20 sec. All the teeth were restored as in Group 1. The specimens were coated with nail varnish leaving 1 mm around the restoration, subjected to thermocycling, basic fuchsin dye penetration, sectioned mesiodistally, and observed under a stereomicroscope. Results. The mean leakage scores of the individual study groups were Group 1 (33.40), Group 2 (7.85), Group 3 (16.40), and Group 4 (24.35). Group 1 without a liner showed maximum leakage. Flowable composite liner precured was the best.