Evaluation of surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites: A comparative study

OBJECTIVES

To evaluate surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites (FB-RBCs) in Class V cavities with enamel or dentin margins before and after thermocycling (TMC).

MATERIALS AND METHODS

Three available FB-RBCs were used; Palfique Bulk Flow (PaBF) (Tokuyama Dental), SDR Flow+ Bulk Fill Flowable (Dentsply Sirona), and I-Flow Bulk Fill (I-Dental). Thirty discs were prepared from each type of FB-RBCs. The discs were subjected to Vickers microhardness tester machine. Class V cavities were prepared on 180 molars. Gingival margins of half the specimens were prepared above CEJ and the other half below CEJ. Cavities were restored with FB-RBCs for gingival marginal adaptation test. Two-way ANOVA was used in microhardness, while three-way ANOVA was used for marginal adaptation.

RESULTS

The used materials showed statistically significant differences in microhardness and marginal adaptation.

CONCLUSIONS

Regarding microhardness, PaBF showed the highest value before TMC and SDR was the highest after TMC. Regarding marginal adaptation, SDR revealed the best marginal adaptation than PaBF and I-flow, either subjected to TMC or not.

CLINICAL SIGNIFICANCE

The longevity of cervical restorations depend on both the location of the cavity margin and the material used. The microfractures in resin composite surface due to low surface microhardness as well as marginal gaps seen in laboratory studies could be considered as an indicative parameter for clinical problem associated with marginal differences.

Effect of sonic oscillation on penetration and marginal adaptation of filled-resin-based fissure sealants

OBJECTIVES

To evaluate the effect of sonic oscillation on penetration depth and marginal adaptation of resin-based fissure sealants.

METHOD AND MATERIALS

Thirty-six extracted human third molars were randomized into three groups: in the HF group, teeth were sealed with a filled-resin-based sealant (Helioseal F); in the Sonic-HF group, teeth were sealed with Helioseal F and subjected to sonic oscillation (Compothixo Device, 140 Hz vibration frequency and ± 150 µm amplitude) before curing; in the CO group, teeth were sealed with an unfilled-resin-based sealant (Clinpro). All teeth were thermocycled for 1,500 cycles at 5°C and 55°C, then sectioned buccolingually into four sections (mesial, two middle, and distal). Sections were evaluated under SEM for marginal adaptation and scored. For penetration depth, three independent measurements from each tooth were recorded under SEM, and data were subjected to statistical analysis.

RESULTS

The group subjected to sonic oscillation (Sonic HF) resulted in significantly superior penetration depth and marginal adaptation compared with the HF group, but with no significant difference compared with the CO group.

CONCLUSIONS

Sonic activation of resin-based sealant increased penetration depth into fissures and marginal adaptation to the enamel wall without decreasing filler load or compromising sealant mechanical properties.

Influence of cement type, excess removal, and polishing on the cement joint

OBJECTIVES

To compare marginal gap width and depth with different cementation systems, excess removal, and after polishing.

METHOD AND MATERIALS

In total, 80 composite crowns were milled, divided into ten groups, and cemented on identical artificial teeth. Eight crowns per group were fixed with (i) zinc phosphate cement (ZnOPh), (ii) glass-ionomer cement (GIC), (iii) resin-reinforced glass-ionomer cement (GIC mod), (iv) dual-curing adhesive composite (Comp dual), or (v) dual-curing self-adhesive composite (Comp SE dual). Excess removal was performed with a scaler after brief light-cure (tack-cure), final light-cure, during rubber or gel phase or by wiping with foam pellet. Curing was completed in chemical, dark cure, or light-curing modus. The specimens were polished and stored in water (37°C). The margins were digitized using a 3D laser-scanning microscope (VK-X100 series, Keyence). The width and the depth of the marginal gap were measured at 10 points between the crown margin and the preparation margin.

RESULTS

The width after excess removal varied between 65.1 ± 15.7 µm (Comp dual, wipe, with polishing) and 208.6 ± 266.7 µm (Comp SE dual, dark cure, without polishing). The depth varied between 29.8 ± 22.2 µm (Comp dual, wipe, with polishing) and 89.5 ± 45.2 µm (Comp SE dual, dark cure, without polishing). The impact on gap width and depth was detected for fixation material, excess removal, and polishing.

CONCLUSION

The gap depth and width depend on the luting material and the mode of access removal. Polishing can improve the gap quality, especially for GIC and resin-based systems.

Bond Strength, Microleakage, Microgaps, and Marginal Adaptation of Self-adhesive Resin Composites to Tooth Substrates with and without Preconditioning with Universal Adhesives

PURPOSE

This study investigated and compared the bond strengths, microleakage, microgaps, and marginal adaptation of self-adhesive resin composites (SAC) to dentin with or without universal adhesives.

MATERIALS AND METHODS

Dentin surfaces of 75 molars were prepared for shear and microtensile bond strength testing (SBS and µTBS). Silicon molds were used to build up direct restorations using the following materials to form 5 groups: 1. Surefil One; 2. Prime&Bond active Universal Adhesive + Surefil One; 3. Vertise Flow; 4. OptiBond Universal + Vertise Flow; 5. Scotchbond Universal + Filtek Z500 (control group). Bonded specimens were thermocycled 10,000x before being tested either for SBS or µTBS using a universal testing machine at a crosshead speed of 0.5 mm/min. Direct mesial and distal class-II cavities were created on 100 sound premolars, with the gingival margin of distal cavities placed below CEJ and restored according to the five groups. After thermocycling, microleakage scores were assessed following immersion of restored premolars in 2% methylene blue dye for 24 h, while marginal gaps and adaptation percentages were investigated on epoxy resin replicas under SEM at magnifications of 2000X and 200X, respectively. Results were statistically analyzed with parametric and non-parametric tests as applicable, with a level of significance set at α = 0.05.

RESULTS

Bond strengths, microleakage scores, microgaps, and percent marginal adaptation of Surefil One and Vertise Flow were significantly (p < 0.001) inferior to the control group. Dentin preconditioning with universal adhesives significantly increased the study parameter outcomes of Surefil One and Vertise Flow, yet they were still significantly below the performance of the control group.

CONCLUSION

Conventional resin composite outperformed the SAC whether applied solely or in conjunction with their corresponding universal adhesives.

Comparison of the marginal and internal fit of PMMA interim crowns printed with different layer thicknesses in 3D-printing technique

OBJECTIVE

The aim of this in vitro study was to compare the effect of printing layer thickness on the marginal and internal fit of interim crowns.

MATERIAL AND METHODS

A maxillary first molar model was prepared for ceramic restoration. Thirty-six crowns were printed with three different layer thicknesses using a digital light processing-based three-dimensional printer (25, 50, and 100 µm [LT 25, LT 50, and LT 100]). The marginal and internal gaps of the crowns were measured with replica technique. An analysis of variance was conducted to determine if there were significant differences between the groups (ɑ = .05).

RESULTS

The marginal gap of LT 100 group was significantly higher than that LT 25 (p = .002) and LT 50 groups (p ≤ .001). The LT 25 group has significantly larger axial gaps than LT 50 group (p = .013); however, there were no statistically significant differences between other groups. The LT 50 group showed the smallest axio-occlusal gap. The mean occlusal gap differed significantly by printing layer thickness (p ≤ .001), with the largest gap occurring for LT 100.

CONCLUSIONS

Provisional crowns printed with 50 µm layer thickness provided the best marginal and internal fit.

CLINICAL SIGNIFICANCE

It is recommended that provisional crowns be printed with a 50 µm layer thickness to ensure optimal marginal and internal fit.

Marginal Adaptation of In Vitro Class II Restorations Made Out of Bulk or Conventional Composite Using Single- or Multi-Layered Techniques

Objective: Testing the influence of various restorative materials (conventional or bulkfill composites) and filling techniques (single- or multi-layered techniques) on the in vitro marginal adaptation of large class II direct composites with supra and sub-gingival margins subjected to thermomechanical loading (TML). Methods: A total of 40 prepared teeth were attributed randomly to five experimental groups. In Group 1, restorations were made of multi-layered high-viscosity conventional composite (Tetric EvoCeram); in Groups 2 and 3, restorations were made of a high viscosity bulkfill composite (Tetric EvoCeram Bulk Fill) applied in one (Group 2) or three layers (Group 3); in Groups 4 and 5, restorations were made of a flowable bulkfill composite (SDR flow) applied in one (Group 4) or two layers (Group 5), covered with a layer of high-viscosity conventional composite (Ceram-X Universal). A single adhesive (OptiBond FL) was used in all groups. All specimens were submitted to a staged TML comprising three phases (2 × 500,000 and 1,000,000 cycles) at 50 N with 3350 thermal cycles (5 to 55 °C) every 500,000 cycles. The tooth-restoration interfaces on proximal surfaces were evaluated quantitatively by scanning electron microscopy, before and after each TML phase, hence at three timepoints (T0, T1, T2 and T3). The following segments were considered for evaluation: proximal, vertical enamel margins (assessed individually on both restoration sides), cervical enamel (restoration side above CEJ) and cervical dentin margin (restoration side below the CEJ). Results: TML induced a significant reduction in continuous adaptation at both enamel and dentin margins in all groups, with percentages of continuous margins ranging from 75.2 to 91.8% at T0, and decreasing to values ranging from 21.3 to 73.9% at T3. Both composite systems and layering protocols had a significant influence on marginal adaptation of the restorations, with statistical associations depending on the restoration group and the timepoint considered. Defective margins in enamel were all of a cohesive nature with micro-fractures, while in dentin, interfacial gaps were the main defect observed. Conclusions/Clinical significance: The present results highlighted significant degradation of marginal adaption after long-term in vitro fatigue test using materials even with high-viscosity conventional resin composites, applied with a proper layering approach in medium-large sub-gingival cavities. While no significant differences were observed at the dentin cervical margins, there was a tendency for better adaptation at the enamel margin when using a higher modulus material with a multi-layered technique.

In Vitro Evaluation of marginal adaptation of polyether ether ketone and zirconia copings

Background

Polyether ether ketone (PEEK) has emerged as a new thermoplastic material with potential applications as a restorative material. Aim: This study aimed to evaluate the marginal adaptation of PEEK copings compared to zirconia copings using field emission scanning electron microscopy.

Materials and Methods

A freshly extracted maxillary central incisor was prepared for a full-coverage restoration following standard principles of tooth preparation. The tooth was sent to a laboratory for fabrication of samples using computer-aided design and manufacturing (CAD/CAM). Twenty samples of polyether ether ketone (PEEK) copings (group A) and 20 of zirconia copings were fabricated (group B). The copings were scanned under a field emission scanning electron microscope and measurements were taken at four distinct points. The marginal adaptation over the buccal, lingual, mesial, and distal margins for both groups was evaluated. One-way analysis of variance (ANOVA) and independent t test were applied.

Results

Our findings indicate that PEEK showed better marginal adaptation than zirconia at all measurement points. The mean marginal gap value of the PEEK group was 33.99 ± 8.81 μm and of the zirconia group was 56.21 ± 15.07 μm. On comparing marginal adaptation among the mesial, distal, buccal, and lingual aspects, PEEK showed better adaptation on all four margins, with the best adaptation on the buccal margin that had the lowest mean gap value of 29.27 ± 6.07 μm. The zirconia group adapted best at the distal margin, with a lowest mean gap value of 53.58 ± 15.25 μm (P ≤ 0.05).

Conclusion

PEEK copings had better marginal adaptation and fit compared to zirconia copings. It may have applications as a restorative material in fixed prostheses.

The Effect of Cement Space Parameters on the Marginal Adaptation of Milled Endocrowns: An In Vitro Study

Background Cement film space plays a significant role in achieving good adaptation of indirect restorations. The objective of this study is to investigate the effect of cement space parameters on the marginal adaptation of computer-aided design (CAD)/computer-assisted manufacturing (CAM) endocrowns. Methodology The coronal part of 10 freshly extracted human mandibular molars was reduced to a level of 1.5 mm above the cementoenamel junction (CEJ); then, root canal treatment was performed. On each tooth, four lithium disilicate endocrowns with different cement space parameters (40, 80, 120, and 160 µm) were designed and fabricated using CAD/CAM. Endocrowns were seated to their prepared teeth, and the vertical marginal gap was measured in 20 equidistant points for each endocrown using a stereomicroscope on 90× magnification. The mean marginal gaps of the four groups were compared using a one-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) test considering p<0.05 as the cutoff for statistical significance. Results The mean marginal gap of the 40 µm, 80 µm, 120 µm, and 160 µm groups were 46.25±21.20 µm, 21.75±11.10 µm, 15.94±06.62 µm, and 13.10±07.08 µm, respectively. One-way ANOVA showed a significant difference in the marginal gaps between groups (p<0.001). The Tukey post hoc test showed a statistically significant mean difference between 40 µm and each of the other three groups (p<0.001). Conclusion The cement space parameter variation affects the marginal adaptation of endocrowns. The cement space of 40 µm resulted in a higher marginal gap than cement spaces of 80, 120, and 160 µm.

Comparative SEM study of the marginal adaptation of MTA and Biodentine after apical resection (in vitro study)

INTRODUCTION

Successful periapical surgery requires appropriate root resection, preparation, and adequate sealing.

AIM

The aim of the present study was to assess the marginal adaptation of MTA and Biodentine after apical resection with an Er:YAG laser and a diamond turbine bur using a scanning electron microscope (SEM).

MATERIALS AND METHODS

The crown part of forty-eight extracted single-root human teeth was removed, and the root canal length of 15 mm was standardized. The root canals were prepared using rotary Ni-Ti Revo-S files up to an apical stop - AS40 and filled with MTA Fillapex and gutta-percha points (cold lateral condensation). The teeth are divided into 2 main groups: group 1 (n=24) after apical resection with a turbine bur, ultrasonic preparation of the retrograde cavity at 3 mm depth and retrograde obturation with Biodentine and MTA; group 2 (n=24) after apical resection with an Er:YAG laser, ultrasonic preparation of the retrograde cavity at a depth of 3 mm and retrograde obturation with MTA and Biodentine. A SEM was used for assessment of the marginal adaptation of the material to the root dentin. The data was entered into and analyzed with IBM SPSS Statistics 22.0.

RESULTS

In the group with apical resection with a turbine bur, a statistically significant difference in the gap size between the material and dentin was found in both materials we studied (MTA and Biodentine). The higher mean value was in MTA (1.72 µm), in Biodentine it was 1.08 µm. In the group with apical resection with Er:YAG laser, no statistically significant difference in the gap size between the material and dentin was found in both studied materials: MTA - 1.88 µm, Biodentine - 1.32 µm.

CONCLUSIONS

In the present study, MTA and Biodentine showed good sealing capabilities after apical resection. Biodentine displayed better marginal adaptation when resecting the root tip using a turbine bur. The Er:YAG laser-assisted apical resection shows sealing of the open dentinal tubules around the resected root surface.

Physical properties, marginal adaptation and bioactivity of an experimental mineral trioxide aggregate-like cement modified with bioactive materials

PURPOSE

To evaluate the effect of adding wollastonite and bioactive glass to an experimental mineral trioxide aggregate-like cement (MTA) on the dimensional stability, compressive strength, solubility, bioactivity, and marginal adaptation by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

METHODS

Four groups were evaluated at 7, 14, and 21 days: MTA Angelus, experimental MTA-like cement (MTA Exp), BG10 (MTA Exp+10 wt% bioactive glass), and WO20 (MTA Exp+20 wt% wollastonite). To evaluate marginal adaptation, extracted teeth were endodontically obturated and root-end cavities were prepared and filled with the tested materials.

RESULTS

Cements with bioactive materials showed minimal dimensional changes. Adding wollastonite or bioactive glass to MTA Exp reduces the compressive strength but does not affect solubility. Bismite (Bi₂O₃), larnite (Ca₂SiO₄), calcite (CaCO₃) and carbonated hydroxyapatite (Ca₅[PO₄,CO₃]₃[OH]) were identified in the four cements; ettringite (Ca₆Al₂[SO₄]₃[OH]₁₂·26H₂O) and bismutite ([BiO]₂CO₃) were only observed in MTA Exp, BG10, and WO20. Cement-dentin interfaces were not observed after 14 days on the BG10 and WO20 cement composites due to the ettringite formation.

CONCLUSION

Acicular growing crystals typical of hydroxyapatite were found on the surfaces of all cements. An improved marginal adaptation was observed with the addition of wollastonite or bioactive glass.

Impact of photodynamic therapy on the marginal adaptation of Biodentine used as root-end filling material

BACKGROUND

The marginal adaptation of root-end filling materials and the effective antibacterial control in a surgical site are crucial for the successful outcome of endodontic surgery.

OBJECTIVE

This study aimed to evaluate the effect of retrograde application of photodynamic therapy on the marginal adaptation of Biodentine used as a root-end filling material.

METHODS

Twenty single-rooted anterior teeth were selected, instrumented and obturated with gutta-percha and AH Plus. The apical 3 mm of the roots were resected and root-end cavities were prepared with an ultrasonic retro-tip. The teeth were randomly divided into two groups (n = 10). In the first group, photodynamic therapy (PDT) was applied in the retrograde cavity prior to the root-end filling. In the second group retro cavity was filled without PDT. All specimens were obturated with Biodentine and afterwards sectioned longitudinally. The gap width at the material-dentin interface was measured using a scanning electron microscope. The results were statistically analyzed.

RESULTS

The produced gap width by Biodentine/PDT was 3.85 μm versus 2.68 μm in the Biodentine control group with significant differences in-between.

CONCLUSION

Under the conditions of this study, PDT has a negative effect on the marginal adaptation of Biodentine used as root-end filling material.

Evaluation of the effect of milling mode and margin definition on adaptation of chairside digitally designed and fabricated ceramic veneers

AIM

The present study aimed to evaluate the effect of the milling mode and margin defining method on the marginal and internal adaptation of digitally designed and fabricated ceramic veneers.

MATERIALS AND METHODS

Forty extracted central incisors were prepared for ceramic veneers. The veneers were categorized into four groups (n = 10) based on the milling mode (fine or extra-fine) and design (automatic or manual defining of cervical and incisal margins). The veneers were cemented to the teeth using resin cement and then polished. After cementation, the teeth were embedded in clear polyester resin, then cut into three sections. Absolute marginal gap at the cervical margins (AMGC), marginal gap at the incisal (MGI) and cervical (MGC) margins, and internal gap (IG) at the axial wall were evaluated using a scanning electron microscope. Two-way analysis of variance (ANOVA) and t tests were used (α = 0.05) for the statistical analysis.

RESULTS

The margin defining method affected the adaptation of the internal and incisal margin; the automatic (software) margin defining method resulted in a smaller MGI (P = 0.038) and IG (P = 0.009) than the manual defining method.

CONCLUSION

The type of milling mode did not affect the marginal gap. The margin defining method affected the marginal gap at the incisal margin and the internal gaps. (Int J Comput Dent 2022;25(3):277-285; doi: 10.3290/j.ijcd.b2588153).

Marginal Adaptation of Flowable vs Sonically Activated or Preheated Resin Composites in Cervical Lesions

PURPOSE

To investigate marginal integrity of restorations applied with preheated and non-preheated composite, flowable composite, sonically activated composite, and a new thermo-viscous bulk-fill composite using near-infrared technology for preheating, in class V cavities of human molars.

MATERIALS AND METHODS

Standardized cavities were prepared on the buccal surfaces of 60 human mandibular molars and restored with one of the following resin composite materials after application of an etch-and-rinse adhesive (OptiBond FL, Kerr): non-preheated or preheated conventional composite (Filtek Supreme XTE, 3M Oral Care), preheated thermo-viscous composite (VisCalor bulk, Voco), soncially activated composite (SonicFill 3, Kerr), or flowable composite (Filtek Supreme XTE Flowable, 3M Oral Care) applied in bulk or as a lining material using the snow-plow technique. After light curing and polishing, the percentage of continuous margins (PCM) of the restorations in enamel and dentin was assessed using SEM both before and after thermomechanical loading (TML). TML was carried out with 3000 thermal cycles (5°C-50°C) and a simultaneous mechanical stress application with 1.2 million load-cycles (1.7 Hz, 49 N) in a computer-controlled masticator. Non-parametric statistical analysis was performed using Wilcoxon, Kruskal-Wallis, and Mann-Whitney U-tests (α = 0.05).

RESULTS

All groups revealed a significant decline in marginal integrity after TML in both enamel and dentin. Although the flowable group in enamel and the snow-plow group in dentin showed the highest PCM before TML, the differences between the groups were compensated after TML.

CONCLUSION

All of the tested composites and application methods showed similar marginal integrities after thermomechanical loading and can be recommended for clinical implementation.

Marginal and internal fit of lithium disilicate endocrowns fabricated using conventional, digital, and combination techniques

OBJECTIVE

To compare the marginal and internal adaptation of endocrowns produced using conventional technique, digital technique, and combination (cast digitization) techniques using microcomputed tomography (micro-CT).

MATERIALS AND METHODS

Ten freshly extracted human mandibular molar teeth were prepared for all-ceramic endocrowns. A total of 40 Lithium Disilicate (IPS e.max) endocrowns were fabricated and grouped according to the impression and production technique to four groups: Group (CO): Conventional impression/heat pressed endocrowns (n = 10), Group (CAD): Direct scanning of teeth/CAD-CAM endocrowns (n = 10), Group (COMIO): Combination; Cast digitization using Intraoral scanner/CAD-CAM endocrowns (n = 10), Group (COML): Combination; Cast digitization using laboratory scanner/CAD-CAM endocrowns (n = 10). Micro-computed tomography was used to measure the marginal and internal gaps in 11 predetermined sites. Mean marginal and internal gaps were compared using analysis of variance and Scheffe's post hoc test.

RESULTS

CO, CAD, COMIO, and COML groups showed significant differences in the mean marginal gap (150 ± 35 μm, 120 ± 27 μm, 110 ± 24 μm, 120 ± 29 μm, respectively p = 0.013), gap at line angle (280 ± 70 μm, 130 ± 37 μm, 140 ± 54 μm, 130 ± 33 μm, respectively, p < 0.001), gap at cavity wall (210 ± 76 μm, 140 ± 43 μm, 140 ± 52 μm, 150 ± 44 μm, respectively, p = 0.010) and gap at pulpal floor (500 ± 150 μm, 240 ± 58 μm, 260 ± 59 μm, 240 ± 64 μm, respectively, p < 0.001).

CONCLUSION

Digitally fabricated endocrowns showed superior marginal and internal fit compared to the conventionally fabricated endocrowns.

CLINICAL SIGNIFICANCE

Marginal and internal adaptation are detrimental factors for the success and survival of dental restorations including endocrowns. When compared with the conventional impressions and conventional production techniques, Digital workflow is more predictable and reliable as it reduces errors and improves the accuracy of fit.

Effect of Different Bonding Techniques on Marginal Adaptation of Harmonize Composite Resin at Different Storage Times

Aim:

The aim of this study is to evaluate the outcome of diverse bonding methods on marginal adaptation of harmonize composite at altered times of storage.

Materials and Methods:

The study was done on 120 upper premolars with two adhesive systems (n = 60), self-etch, and total-etch type. Sixty teeth of each method were stored at three different times (n = 20) 1 day, 3, and 6 months. Class II cavities were made in all teeth restored with Harmonize composite incrementally. Then, each tooth was sectioned into two halves in buccolingual direction and observed with stereomicroscope for detecting any gaps and scanning electron microscope to assess resin-dentin junction.

Results:

Mean gap area was more in the self-etch group at the cervical and occlusal margins. Storage period of 6 months revealed significantly highest mean gap area.

Conclusions:

Total-etch system showed better marginal adaptation than the self-etch system and storage of resin in water has unfavorable marginal adaptation.

Comparative Evaluation of Internal Margin Adaptation and Integrity of Class I Preparations using Two Composites: An In Vitro Study

Aim and Objectives:

The aim of this study is to evaluate the internal margin adaptation and integrity of Class 1 preparations using two composites types (bulk fill/conventional) with two placement methods (4/2 mm increments).

Materials and Methods:

Class 1 preparations of 4 mm × 4 mm dimensions were made on 30 extracted human mandibular molars. They were randomly divided into three groups; among them, in Group 1 (n = 10), cavities were filled with SureFil SDR Bulk Fill, Group 2 (n = 10) cavities were filled with Filtek Bulk Fill of 4 mm increments in both groups, and in Group 3 (n = 10), cavities were filled with conventional composite Filtek Z350 with 2 mm increments. Samples were sectioned occlusogingivally. Then, dye was on internal margins, and images of each specimen were recorded using a digital camera to evaluate the marginal integrity and adaptation of restorative material to the tooth surface with image analysis software. Then, collected data were put under the statistical analysis with analysis of variance test and post hoc Tukey's test.

Results:

There was no significant difference in overall dye penetration in bulk fill and conventional (incremental fill) composite resins; however, when dye penetration was evaluated at different locations, within enamel and mid-dentin, significantly more gap-free margins were found than at the pulpal interface. Filtek Bulk Fill and conventional composite (Filtek Z350) showed comparatively more dye penetration toward the pulpal interface compared to SDR Bulk Fill.

Conclusion:

There were no significant differences in percentage of gap-free margins between fill types for any of the composite materials. The proportions of gap-free margin were less at the pulpal interface and mid-dentin portions and enamel when filled with 4 and 2 mm increments.

ToF-SIMS Analysis of Demineralized Dentin Biomodified with Calcium Phosphate and Collagen Crosslinking: Effect on Marginal Adaptation of Class V Adhesive Restorations

This study aimed to assess the effect of biomodification before adhesive procedures on the tooth-restoration interface of class V restorations located in caries-simulated vs. sound dentin, and the quality of dentin surface by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Class V cavities located on cervical dentin were prepared on the buccal surfaces of extracted human molars under the simulation of intratubular fluid flow. Two dentin types, i.e., sound and demineralized by formic-acid, were biomodified with 1% riboflavin and calcium phosphate (CaP) prior to the application of a universal adhesive (Clearfil Universal Bond) in etch and rinse or self-etch mode, and a conventional micro hybrid composite (Clearfil APX). Restorations were subjected to thermo mechanical fatigue test and percentages of continuous margins (% CM) before/after fatigue were compared. Bio modification of dentin surfaces at the molecular level was analyzed by Time-of-Flight Secondary Mass Spectometry (ToF-SIMS). % CM were still significantly higher in tooth-restoration interfaces on sound dentin. Meanwhile, biomodification with riboflavin and CaP had no detrimental effect on adhesion and in carious dentin, it improved the % CM both before and after loading. Etching carious dentin with phosphoric acid provided with the lowest results, leading even to restoration loss. The presence of molecule fragments of riboflavin and CaP were detected by ToF-SIMS, evidencing dentin biomodification. The adhesive interface involving carious dentin could be improved by the use of a collagen crosslinker and CaP prior to adhesive procedures.

Relationships between Flexural and Bonding Properties, Marginal Adaptation, and Polymerization Shrinkage in Flowable Composite Restorations for Dental Application

To evaluate the flexural and bonding properties, marginal adaptation, and polymerization shrinkage in flowable composite restorations and their relationships, four new generation flowable composites, one conventional, and one bulk-fill flowable composite were used in this study. Flexural properties of the composites and shear bond strength to enamel and dentin for flowable restorations were measured immediately and 24 h after polymerization. Marginal adaptation, polymerization shrinkage, and stress were also investigated immediately after polymerization. The flexural properties, and bond strength of the flowable composites to enamel and dentin were much lower immediately after polymerization than at 24 h, regardless of the type of the composite. Polymerization shrinkage and stress varied depending on the material, and bulk-fill flowable composite showed much lower values than the others. The marginal adaptation and polymerization shrinkage of the composites appeared to have a much stronger correlation with a shear bond strength to dentin than to enamel. The weak mechanical properties and bond strengths of flowable composites in the early stage after polymerization must be taken into account when using them in the clinic. In addition, clinicians should be aware that polymerization shrinkage of flowable composites can still lead to the formation of gaps and failure of adaptation to the cavity regardless of the type of composite.

Marginal Adaptation and Micropermeability of Class II Cavities Restored with Three Different Types of Resin Composites-A Comparative Ten-Month In Vitro Study

The development of composite materials is subject to the desire to overcome polymerization shrinkage and generated polymerization stress. An indicator characterizing the properties of restorative materials, with specific importance for preventing secondary caries, is the integrity and durability of marginal sealing. It is a reflection of the effects of polymerization shrinkage and generated stress. The present study aimed to evaluate and correlate marginal integrity and micropermeability in second-class cavities restored with three different types of composites, representing different strategies to reduce polymerization shrinkage and stress: nanocomposite, silorane, and bulk-fill composite after a ten-month ageing period. Thirty standardized class ΙΙ cavities were prepared on extracted human molars. Gingival margins were 1 mm apical to the cementoenamel junction. Cavities were randomly divided into three groups, based on the composites used: FiltekUltimate-nanocomposite; Filtek Silorane LS-silorane; SonicFill-bulk-fill composite. All specimens were subjected to thermal cycles after that, dipped in saline for 10-mounds. After ageing, samples were immersed in a 2% methylene blue. Thus prepared, they were covered directly with gold and analyzed on SEM for assessment of marginal seal. When the SEM analysis was completed, the teeth were included into epoxy blocks and cut longitudinally on three slices for each cavity. An assessment of microleakage on stereomicroscope followed. Results were statistically analyzed. For marginal seal evaluation: F.Ultimate and F.Silorane differ statistically with more excellent results than SonicFill for marginal adaptation to the gingival margin, located entirely in the dentin. For microleakage evaluation: F.Ultimate and F.Silorane differ statistically with less microleakage than SonicFill. Based on the results obtained: a strong correlation is found between excellent results for marginal adaptation to the marginal gingival ridge and micropermeability at the direction to the axial wall. We observe a more significant influence of time at the gingival margin of the cavities. There is a significant increase in the presence of marginal fissures (p = 0.001). A significant impact of time (p < 0.000) and of the material (p < 0.000) was found in the analysis of the microleakage.

Micro-computed tomographic analysis of the marginal adaptation of a calcium silicate-based cement to radicular dentin after removal of three different intracanal medicaments - An in vitro study

Context

This study focuses on the marginal adaptation of a calcium silicate-based cement to the root dentin after retrieval of different intracanal medicaments.

Aim

This study compared the marginal adaptation of a calcium silicate-based cement to radicular dentin in the apical third of the root canal following the use of three different intracanal medicaments.

Materials and Methods

Forty single-rooted premolar teeth (n = 40) were decoronated 13 mm above the root apices; then, 3 mm of the root tips were resected to standardize the root length. Orthograde cleaning and shaping were done using the rotary files and apical enlargement using peeso reamers. Depending on the intracanal medicament used, the samples were equally divided into four groups: Group 1 - control, Group 2 - Metapex, Group 3 - triple antibiotic paste (TAP), and Group 4 - calcium hydroxide with Propolis. Subsequently, the medicament was removed and a 3 mm apical barrier of Biodentine^TM was placed and later scanned using an ex vivo micro-computed tomography scanner.

Statistical Analysis Used

One-way ANOVA F-test and Tukey's post hoc test were used.

Results

Maximum adaptation was seen in control group (0.65) > Propolis (1.47) > TAP (4.37) > Metapex (5.25); a high statistically significant difference between the four groups was found (P < 0.001) with regard to the external voids between Biodentine^TM and radicular dentin.

Conclusion

On comparison of the marginal adaptation of Biodentine to root canal dentin following the use of three different intracanal medicaments, maximum adaptation was seen in Group 1, followed by Group 4, Group 3, and Group 2.

Evaluation of Internal Fit and Marginal Adaptation of Provisional Crowns Fabricated with Three Different Techniques

Different techniques have been used to construct provisional crowns to protect prepared teeth. The purpose of this in vitro study was to assess the internal fit and marginal discrepancy of provisional crowns made by different methods. A total of 48 provisional crowns were constructed and divided into three groups (n = 16) according to the fabrication methods: fabricated manually-group MAN; computer-aided design/computer aided manufacturing technology-group CAM; and 3-dimensional (3D)-printed technology-group 3DP. The same standard tessellation language (STL) file was used for both CAD/CAM and 3D-printed group. The silicone-checked method was used to measure the internal gap distance. The marginal discrepancy was measured by using the polyvinyl siloxane (PVS) replica method and swept-source optical coherence tomography (OCT) scanning technique. Data were analyzed with one-way analysis of variance (ANOVA) nonparametric Kruskal-Wallis and Tukey tests at α = 0.05. At the central pit and axial walls, the gap distance mean values of group CAM were higher than those from group MAN and 3DP. The group 3DP was statistically significantly higher in gap distance at the location of occlusion than group MAN and group CAM (p < 0.05). The total gap distances assessed by silicone-checked method revealed there were no statistically significant differences between the tested groups (p > 0.05). The total mean values of absolute and horizontal marginal discrepancy of the group 3DP obtained by using the PVS-replica method and OCT scanning technique were significantly higher than the group MAN and CAM (p < 0.05). Regression correlation results of marginal discrepancy indicated a positive correlation (r = 0.902) between PVS-replica method and OCT scanning technique. The manually fabricated provisional crowns presented better internal fit and a smaller marginal discrepancy. Between different assessment techniques for marginal adaptation, PVS-replica method and OCT scanning technique have a positive correlation.

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

OBJECTIVE

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.

OVERVIEW

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.

CLINICAL SIGNIFICANCE

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.

Impact of Different Etching Strategies on Margin Integrity of Conservative Composite Restorations in Demineralized Enamel

Good margin integrity with a tight seal of the adhesive interface is considered one of the key factors for the clinical success of composite restorations. This study investigated the effect of enamel etching with phosphoric acid on the margin integrity of self-etch bonded composite restorations in demineralized enamel. Crowns of bovine incisors were assigned into 14 groups (n = 10 per group) of which ten groups (groups 1–5 and 8–12) were demineralized (21 days, acid buffer, pH 4.95) to create artificial carious lesions. Standardized Class V cavities were prepared in all specimens. Demineralized groups were either etched with phosphoric acid for 10, 30, 60, or 120 s (groups 2–5 and 9–12), or no etching was performed (groups 1 and 8). The non-demineralized (sound) groups were etched for 10 s (groups 7 and 14) or remained non-etched (groups 6 and 13). Resin composite restorations were then placed using either a one-step (iBond Self Etch, groups 1–7) or two-step self-etch adhesive (Clearfil SE Bond, groups 8–14). Margin integrity of the restorations was assessed after thermocycling (5000×, 5–55 °C) using scanning electron microscopy, and the percentage of continuous margins (%CM) was statistically analyzed (α = 0.05). Phosphoric acid etching significantly increased %CM in both demineralized and sound enamel. For iBond Self Etch, a significant increase in %CM in demineralized enamel was observed with increased etching times. All etched groups treated with Clearfil SE Bond and those etched for 60 or 120 s and treated with iBond Self Etch showed similar %CM in demineralized enamel as in etched sound enamel, and significantly higher %CM than in non-etched sound enamel. In conclusion, enamel etching with phosphoric acid improves margin integrity of composite restorations in demineralized enamel when bonded with the examined adhesives.

A Comparative In Vitro Study Evaluating the Marginal Adaptation of Zirconium Computer-Aided Design/Computer-Aided Manufacture and Press-ceramic Veneers

INTRODUCTION

One method to evaluate the clinical success of cemented restorations is measuring the marginal adaptation. There is a correlation between the fitting of the restoration and problems caused by clinically undetectable passage of bacteria between the tooth structure and the veneer.

AIM

To evaluate in comparison the marginal adaptation of veneers produced via CAD/CAM and press technique.

MATERIALS AND METHODS

32 extracted incisors are divided into two equal-number groups (n=16) according to the production technique - CAD/CAM zirconium veneers and press-ceramic veneers. Cut sections are examined under a SEM magnification. Marginal accuracy is measured as the distance between the finish line of the tooth and the margin of the veneer at eight fixed locations.

RESULTS

The mean values of marginal gap of group 1 are: external adaptation - 79.88±3.71 µm; internal adaptation - 79.14±15.70 µm; cervical adaptation - 82.39±28.55 µm; incisal adaptation - 86.85±21.72 µm. The mean values of marginal gap of group 2 are: external adaptation - 100.31±2.16 µm; for internal adaptation - 101.01±12.51 µm; cervical adaptation - 91.55±3.31 µm; incisal adaptation - 93.76±2.54 µm.

CONCLUSIONS

Veneers produced via CAD/CAM technology have better fit at the external and internal marginal wall. There is no statistically significant difference between the gaps at the cervical and the incisal areas.

Marginal adaptation and fracture strength of endocrowns manufactured with different restorative materials: SEM and mechanical evaluation

Endocrowns were manufactured using different restorative materials to evaluate the marginal adaptation and fracture strength. Fifty endodontically treated mandibular first molar teeth were divided into five groups (n = 10). Endocrowns were obtained from lithium disilicate glass ceramic ingots by heat-press technique (Group e.max Press: GEP), and from feldspathic blocks (Group Cerec: GC), polymer infiltrated ceramic network blocks (Group Enamic: GE), lithium disilicate glass ceramic blocks (Group e.max CAD: GEC), and zirconia-reinforced glass ceramic blocks (Group Suprinity: GS) by CAD/CAM technique. After thermocycling, marginal adaptation was evaluated under scanning electron microscope at ×200 magnification. The specimens' fracture strengths were tested in universal test machine, and fracture types were evaluated. Statistical analyses were performed with Kruskal-Wallis test. The highest marginal gap value was found in GEP, but no significant differences were determined among the other four groups (p > .05). Significant differences were observed among the groups in terms of fracture strength (p = .019). The fracture strength values of GEC were significantly higher than GE, GC, and GS (p < .05). Values were not significantly different between the GEC and GEP groups (p > .05). CAD/CAM endocrowns showed better marginal adaptation than heat-pressed endocrowns. Clinically acceptable marginal gaps were seen in both endocrown types. Both CAD/CAM and heat-pressed lithium disilicate glass ceramic endocrowns showed higher fracture strength.

Margin Integrity of Bulk-Fill Composite Restorations in Primary Teeth

This in vitro study examined the margin integrity of sculptable and flowable bulk-fill resin composites in Class II cavities of primary molars. Standardized Class II cavities were prepared in human primary molars and restored with the following resin composite materials after application of a universal adhesive: a sculptable bulk-fill composite (Tetric EvoCeram Bulk Fill (TEC) or Admira Fusion x-tra (AFX)), a flowable bulk-fill composite (Venus Bulk Fill (VBF) or SDR), or a conventional composite (Filtek Supreme XTE (FS)). The bulk-fill materials were applied in 4 mm layers, while the conventional composite was applied in either 2 mm (FS2, positive control) or 4 mm layers (FS4, negative control). The specimens were exposed to thermo-mechanical loading (TML) in a computer-controlled masticator. A quantitative margin analysis was performed both before and after TML using scanning electron microscopy, and the percentage of continuous margins (margin integrity) was statistically analyzed (α = 0.05). All composites showed a significant decline in margin integrity after TML. AFX exhibited the significantly highest margin integrity of all materials after TML (97.5 ± 2.3%), followed by FS2 (79.2 ± 10.8%), TEC (73.0 ± 9.1%), and FS4 (71.3 ± 14.6%). SDR (43.6 ± 22.3%) and VBF (25.0 ± 8.5%) revealed the lowest margin integrity. In conclusion, the tested sculptable bulk-fill materials show similar or better margin integrity in primary molars than the conventional resin composite placed in 2 mm increments.

Accuracy of marginal adaptation of posterior fixed dental prosthesis made from digital impression technique: A systematic review

Aim

The aim of this systematic review was to investigate the marginal adaptation of three or four unit fixed dental prosthesis (FDP) fabricated with digital impression techniques to those fabricated using any other impression technique.

Settings and Design

Database/electronic searches were conducted till August 2019 in PUBMED-MEDLINE, SCOPUS, and Cochrane library. To identify published articles, multiple keywords were used to develop a search strategy in various combinations. Manual searching of articles was also done. Clinicaltrials.gov.in WHOICTRP and CTRI websites were also searched. Two independent reviewers (TP and VK) assessed eligibility for inclusion, extracted data, and assessed quality using the Cochrane risk of bias tool.

Results

Database search identified 497 citations and four citations through manual search. After removing duplicates and going through abstracts, 23 articles were perused for full-text screening. Two articles met the inclusion criteria; characteristics were described qualitatively, with two studies having overall low risk of bias.

Conclusions

Marginal adaptation of FDPs fabricated using the digital and conventional impressions method was within the clinically acceptable limits. However, more robust clinical trials need to be conducted with large sample size to validate the conclusions.

Marginal adaptation and fracture resistance of feldspathic and polymer-infiltrated ceramic network CAD/CAM endocrowns for maxillary premolars

OBJECTIVE

The aim of this study was to evaluate the marginal adaptation and fracture resistance of feldspathic and Polymer-Infiltrated Ceramic Network (PICN) CAD/CAM endocrowns for maxillary premolars.

MATERIALS AND METHODS

Twenty extracted human permanent maxillary premolars were randomly divided into two groups (n = 10); Group CEREC (GC), which was produced by feldspathic ceramic and the Group Enamic (GE), which was produced by PICN. All teeth were endodontically treated and decoronated horizontally at 2 mm above the cemento-enamel junction. Endocrown preparations were done with 4 mm depth into the pulp chamber. Endocrowns were manufactured using CAD/CAM from ceramic blocks. Following adhesive cementation, all specimens were subjected to thermocycling. Marginal adaptation evaluated under SEM at 200 × magnification. Each specimen was fixed in a universal testing machine and a compressive load was applied at 45° to long axis of the teeth until failure. Failure load was recorded and failure modes were evaluated. Statistical analyses were performed with SPSS 19.0 software and data were compared using Mann-Whitney U test.

RESULTS

There were no significant differences in the marginal adaptation between two groups (P > 0.05). GE presented significantly higher fracture resistance when compared to GC (P < 0.05). Failure pattern was similar and characterized by the tooth-ceramic fracture on the force-applied side.

CONCLUSIONS

CAD/CAM fabricated feldspathic ceramic and PICN endocrowns provide sufficient marginal adaptation, but the PICN endocrowns shows higher fracture resistance than the feldspathic ceramic endocrowns.

Randomized clinical trial of four adhesion strategies: A 42 month study

Context

The adhesives clinical effectiveness has been extensively reported for noncarious cervical lesions (NCCLs). However, there is a lack of information about the adhesive systems strategies and their effect on NCCL restoration longevity.

Aims

This study aims to evaluate a 42-month performance of four dentin adhesive systems used for the restorative treatment of NCCLs.

Settings and Design

NCCLs were randomly divided into four groups: (1) Scotchbond multi-purpose (MP); 2: Single bond plus (SB); 3: Scotchbond SE (SE); and 4: Easy bond (EB).

Subjects and Methods

NCCLs (125) were randomly distributed: (1) MP; (2) SB; (3) SE; and (4) EB and were restored with a nanofilled resin-composite, evaluated along 18-36-42 months.

Statistical Analysis Used

Kruskal-Wallis test: Comparison among the adhesive systems in each period. Friedman analysis: Comparison along the periods. Kaplan-Meier: Survival analysis.

Results

Baseline and 42-month retention (RET) rates (%) were 100/100 for MP; 100/94.74 for SB; 100/87.5 for SE; and 100/100 for EB. The cumulative failure percentage was 9.52% for MP, 9.52% SB, 15.8% SE, and 10% EB. Restorations survival was not dependent on the used adhesive type. Marginal adaptation (MA) was similar to each group, but EB presented noticeable marginal deterioration. Wear was noticed in the 3-step etch-and-rinse (MP) restorations evaluated after 42 months. For the EB, baseline and 18-month wear evaluation were statistically similar. After 36 and 42 months, wear was also similar for EB.

Conclusions

Adhesive systems showed similar performance within most important adhesive bonding efficiency achievement parameters: RET, MA, interfacial staining, recurrent caries, and postoperative sensitivity evaluated during 42 months.

Digital versus conventional impressions for full-coverage restorations: A systematic review and meta-analysis

BACKGROUND

The primary objective of this systematic review was to investigate the survival of full-coverage restorations fabricated by using digital impressions (DIs) versus that of those fabricated by using conventional impressions. The authors also compared secondary outcomes of marginal and internal fit and occlusal and interproximal contacts.

TYPES OF STUDIES REVIEWED

The authors conducted a systematic literature search in multiple databases to identify clinical trials with no restrictions by publication type, date, or language. The authors assessed study-level risk of bias and outcome-level strength of evidence. The authors performed a meta-analysis by using a random-effects model.

RESULTS

Ten studies met the inclusion criteria. The authors identified no studies in which the investigators compared the impression techniques with respect to survival of full-coverage restorations. Mean differences for marginal gap and internal gap were -9.0 micrometers (95% confidence interval, -18.9 to 0.9) and -15.6 μm (95% confidence interval, -42.6 to 11.4), respectively. Studies assessing internal gap were substantially heterogeneous (I² = 72%; P = .003).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Research is lacking to draw robust conclusions about the relative benefits of DIs in terms of restoration survival. Low-quality evidence for marginal fit and internal fit suggested similar performance for both techniques. Evidence quality for interproximal contact and occlusal contact was very low and insufficient to draw any conclusions regarding how the impression techniques compared. Given the uncertainty of the evidence, results should be interpreted with caution. With increasing popularity and adoption of digital scanners by dentists, pragmatic practice-based trials involving standardized, patient-centered outcomes may improve confidence in the comparative effectiveness of DIs.

A clinical comparison of digital and conventional impression techniques regarding finish line locations and impression time

OBJECTIVE

This study compared digital and conventional impression techniques regarding impression time, frequency of adjustments, and adaptation of cobalt-chromium (Co-Cr) copings with supragingival and subgingival finish lines.

MATERIALS AND METHODS

Thirty premolars prepared for single-unit metal-ceramic restorations with supragingival and subgingival finish lines (n = 15). Conventional impression and digital scan of prepared teeth were made. Using computer aided design/computer aided manufacturing (CAD/CAM) system the copings were produced by a milling machine from Co-Cr blocks and internal and marginal discrepancies were measured using silicone replica technique. Data were analyzed using repeated measures ANOVA and Mann-Whitney test (alpha = .05).

RESULTS

The impression technique had a significant effect on the magnitude of gap (P < .001). The internal and marginal gaps in the digital technique (49.43 μ and 60.07 μ, respectively) were significantly lower than the values in the conventional method (91.88 μ and 96.96 μ, respectively-P < .001). Finish line positions had no significant effect on the fit and marginal gap of copings (P = .54 and .243, respectively). The mean impression time (19':27″ in conventional technique and 10':31″ in digital technique) was significantly shorter (P < .001) and the mean frequency of adjustments (2.2 times for conventional and 1.3 times for digital technique) was significantly lower in the digital technique (P < .001). The gingival biotype (thick or thin) had no significant effect on marginal and internal fit (P = .052 and .319, respectively).

CONCLUSION

The digital technique was superior in terms of fit, impression time, and frequency of adjustments. Finish line positions had no significant effect on the fit of copings.

CLINICAL SIGNIFICANCE

Using intraoral scanner promotes the fits of restorations in supragingival and subgingival finish lines.

Evaluation of Bond Strength, Nanoleakage, and Marginal Adaptation of Bulk-fill Composites Submitted to Thermomechanical Aging

PURPOSE

To evaluate the bond strength (BS), nanoleakage, and marginal adaptation (MA) of three bulk-fill and one conventional composite, submitted or not to mechanical and thermal cycling.

MATERIALS AND METHODS

Ninety-six molars were selected and 4-mm-deep class I cavities were prepared and restored. Half of the teeth were submitted to mechanical and thermal cycling (MTC). Teeth were divided into 8 groups (n = 12), according to the composite used - Filtek Z350 XT (Z350), Tetric N-Ceram Bulk Fill (TET), Filtek Bulk Fill Posterior Restorative (FBF) and SonicFill (SF) - and aging, submitted or not to MTC. Fifty-six teeth (n = 7) were used for bond-strength testing, which was performed on stick-shaped specimens obtained from the restored area. Two sticks per tooth were selected to assess nanoleakage. For MA analysis, 40 teeth (n = 5) were sectioned parallel and perpendicular to the occlusal surface and resin-based replicas from the obtained surfaces were prepared. Fracture pattern, nanoleakage, and MA were evaluated using SEM. Quantitative analysis of nanoleakage and MA were performed with ImageJ software. Data obtained were submitted to two-way ANOVA and Tukey's test (ɑ = 0.05).

RESULTS

TET presented good MA and higher values of BS when compared to SF. Z350 and FBF presented poorer MA and lower BS, which was statically similar to the other groups. SF obtained the best MA values. Regarding nanoleakage, the highest values were obtained for TET, which differed significantly from the other groups, which presented similar results among themselves. Aging by MTC solely affected MA.

CONCLUSION

Bulk-fill composites presented similar performance to the conventional nanocomposite and remained stable when aged.

Comparative evaluation of marginal adaptation and microleakage of low-shrinking composites after thermocycling and mechanical loading

AIMS

The aim of this study was to evaluate and correlate marginal adaptation and microleakage of different low-shrinking composites.

MATERIALS AND METHODS

Standardized class V cavities (n = 20/group) with occlusal margin in enamel and gingival margin in dentin were restored with low-shrinking silorane-based (Filtek Silorane) or methacrylate-based (Clearfil Majesty Posterior, Grandio, Reflexions XLS, Tetric EvoCeram, Premise, Ceram-X Duo, Aelite LS Posterior) composites and a conventional composite (Filtek Z250). All teeth were stored in water (24 h), thermocycled (5000×), and mechanically loaded (60,000×). Marginal adaptation of epoxy resin replicas was analyzed using scanning electron microscope. Microleakage of the restoration was assessed by dye penetration on sectioned specimens under stereomicroscopy. Data were statistically analyzed with Mann-Whitney U test, with a significance of P < 0.05. Pearson's correlation test was used to evaluate the correlation between results of margin analysis and microleakage.

RESULTS

No statistical difference in marginal gap formation was determined between Filtek Silorane and Z250. The lowest microleakage score at dentin margins was recorded for Filtek Silorane, which was not significantly different from that of all other groups. No similar ranking between the results of microleakage at enamel and dentin margins was observed for the materials tested. Marginal adaptation was not correlated to microleakage, except for Filtek Silorane, Grandio, and Filtek Z250.

CONCLUSIONS

Compared to the conventional composite Filtek Z250, Filtek Silorane demonstrated no improvements with reduced marginal gap formation. Low-shrinking properties of composites appear to have no ability of sealing restoration margins and preventing leakage.

Influence of preparation designs on marginal adaptation and failure load of full-coverage occlusal veneers after thermomechanical aging simulation

OBJECTIVES

To evaluate the fracture resistance and marginal quality of maxillary molars restored using lithium disilicate glass-ceramic (LDG) occlusal veneers with two preparation designs.

METHODS

Sixteen extracted maxillary molars were assigned to two groups (n = 8). In group 1 (G1), the teeth received a preparation for a conservative full-coverage occlusal veneer restoration with a 90° rounded shoulder margin. In group 2 (G2), the teeth underwent a 1-mm cusp reduction with a marginal chamfer. LDG restorations (IPS e.max CAD) were obtained with the Cerec 3 CAD/CAM system and luted with Variolink II cement. After thermomechanical aging (1 250 000 cycles), the specimens were loaded to fracture. A semiquantitative marginal seal evaluation was performed observing resin replicas of the specimens at the scanning electron microscope. Cement thickness was assessed at the stereomicroscope on sectioned specimens. Collected data were statistically analyzed by parametric and nonparametric tests.

RESULTS

The maximum load to fracture was 2395.01 ± 150.96 N in G1 and 2408.39 ± 112.66 N in G2. Most of the observed specimens exhibited restorable fractures and continuous margins. Cement thickness was 132 ± 38 μm in G1 and 150 ± 41 μm in G2. No differences between the groups emerged.

CONCLUSION

This study demonstrated similar satisfactory performance of the two considered preparations designs for occlusal veneer with LDG.

CLINICAL SIGNIFICANCE

A new minimally invasive occlusal veneer preparation with marginal chamfer exhibited promising fracture resistance and marginal adaptation that were comparable to those of a standard conservative preparation for the restoration of molars with CAD/CAM lithium disilicate occlusal veneers.

Evaluation of the Marginal and Internal Fit of Implant-Supported Metal Copings Fabricated with 3 Different Techniques: An In Vitro Study

PURPOSE

To compare the marginal and internal fit of cobalt-chromium (Co-Cr) alloy copings fabricated by with lost wax technique (LW), computer-aided design and computer-aided manufacturing (CAD/CAM), and direct metal laser sintering (DMLS).

MATERIALS AND METHODS

Thirty-six tissue level, straight titanium abutments were screwed onto implant replicas. All specimens were embedded in acrylic resin and randomly divided into 3 subgroups according to the fabrication of metal coping: LW, CAD/CAM, and DMLS. In total, 36 (n = 12/group) Co-Cr implant-supported metal copings were prepared. Marginal, intermarginal, axial, and occlusal fits of each coping were measured using the silicone replica technique. The data were evaluated statistically using one-way ANOVA and Bonferioni post-hoc test (α = 0.05).

RESULTS

The CAD/CAM group showed significantly lower marginal fit than the LW group and DMLS groups (p < 0.001). The marginal fit of the LW group was not significantly different from the DMLS group (p = 0.721). No significant difference found among the fabrication methods in terms of intermarginal fit (p = 0.913). The CAD/CAM group showed lower axial fit than the LW group (p = 0.026), but there was no statistical difference between the DMLS group and the LW (p = 0.999) and CAD/CAM groups (p = 0.247). No significant differences found among the fabrication methods in terms of occlusal fit (p = 0.158).

CONCLUSIONS

The LW and DMLS groups showed better marginal fit compared to the CAD/CAM group; however, the CAD/CAM group was better than the LW group in terms of axial fit. All fabrication methods demonstrated similar intermarginal and occlusal fit.

A Novel Full-Digital Protocol (SCAN-PLAN-MAKE-DONE®) for the Design and Fabrication of Implant-Supported Monolithic Translucent Zirconia Crowns Cemented on Customized Hybrid Abutments: A Retrospective Clinical Study on 25 Patients

Purpose: To present a novel, full-digital protocol for the design and fabrication of implant-supported monolithic translucent zirconia crowns cemented on customized hybrid abutments. Methods: The present retrospective clinical study was based on data from patients who had been treated with single Morse-taper connection implants (Exacone^®, Leone Implants, Florence, Italy) and were prosthetically restored with monolithic translucent zirconia crowns, cemented on customized hybrid abutments. The full-digital protocol (SCAN-PLAN-MAKE-DONE^®) consisted of 8 phases: (1) intraoral scan of the implant position with scanbody; (2) computer-assisted design (CAD) of the individual abutment (saved as “supplementary abutment design” in external folder) and temporary crown; (3) milling of the individual zirconia abutment and of the temporary polymethyl-methacrylate (PMMA) crown, with extraoral cementation of the zirconia abutment on the relative titanium bonding base, to generate an individual hybrid abutment; (4) clinical application of the individual hybrid abutment and cementation of the temporary PMMA crown; (5) two months later, intraoral scan of the individual hybrid abutment in position; (6) CAD of the final crown with margin line design on the previously saved “supplementary abutment design”, superimposed on the second scan of the abutment in position; (7) milling of the final crown in monolithic translucent zirconia, sintering, and characterization; and (8) clinical application of the final crown. All patients were followed for a period of 1 year. The primary outcomes of this study were the marginal adaptation of the final crown (checked clinically and radiographically), the quality of occlusal and interproximal contact points at delivery, and the aesthetic integration; the secondary outcomes were the 1-year survival and success of the implant-supported restoration. An implant-supported restoration was considered successful in the absence of any biological or prosthetic complication, during the entire follow-up period. Results: In total, 25 patients (12 males, 13 females; 26–74 years of age; mean age 51.1 ± 13.3 years) who had been restored with 40 implant-supported monolithic translucent zirconia crowns were included in this study. At delivery, the marginal adaptation was perfect for all crowns. However, there were occlusal issues (2/40 crowns: 5%), interproximal issues (1/40 crowns: 2.5%), and aesthetic issues (1/40 crowns: 2.5%). The overall incidence of issues at delivery was therefore 10% (4/40 crowns). At 1 year, one implant failed; thus the survival of the restorations was 97.5% (39/40 crowns in function). Among the surviving implant-supported restorations, three experienced complications (one loss of connection between the hybrid abutment and the implant, one decementation of the zirconia abutment, and one decementation of the zirconia crown). The success of restorations amounted to 92.4%. Conclusions: The restoration of single Morse-taper connection implants with monolithic translucent zirconia crowns cemented on customized hybrid abutments via the novel SCAN-PLAN-MAKE-DONE^® full-digital protocol seems to represent a reliable treatment option. However, further studies on a larger number of patients and dealing with different prosthetic restorations (such as implant-supported fixed partial prostheses) are needed to confirm the validity of this protocol.

Bacterial leakage and marginal adaptation of various bioceramics as apical plug in open apex model

AIM

The aim of the present study was to investigate bacterial leakage and marginal adaptation of bioceramic apical plugs.

METHODS

Extracted human mandibular premolars were prepared to simulate open apex using No. 4 Peeso reamer in retrograde direction. In total, 150 specimens were divided into 10 groups by obturation with five bioceramics in two thicknesses. Groups 1, 3, 5, 7, and 9 were obturated with ProRootMTA, Biodentine, TotalFill BC RRM paste, TotalFill BC RRM putty, and RetroMTA at 3 mm, and groups 2, 4, 6, 8, and 10 were obturated with the same materials at 4 mm. Ten specimens in each group were evaluated for bacterial leakage of Enterococcus faecalis for 75 days. Five specimens from each group were sectioned to investigate the gap area under scanning electron microscope.

RESULTS

The 3- and 4-mm Biodentine and TotalFill BC RRM putty groups and the 4-mm ProRootMTA group exhibited less bacterial leakage and lower mean percentage of gap area than those of the other groups. TotalFill BC RRM paste showed the highest leakage for both the 3- and 4-mm groups.

CONCLUSION

The 3- and 4-mm Biodentine and TotalFill BC RRM putty groups and the 4-mm ProRootMTA group exhibited the best sealing ability and marginal adaptation of apical plugs.

Effect of polyethylene fiber reinforcement on marginal adaptation of composite resin in Class II preparations

The aim of this study was to evaluate the effect of polyethylene fibers incorporated in a composite resin matrix on the gingival marginal adaptation of Class II slot restorations. Sixty Class II slot cavity preparations were divided into 2 groups. A fiber-reinforced resin (FRR) group received restorations of composite resin mixed with strips of polyethylene fiber, and an unreinforced resin (UR) group was restored with only composite resin. The groups were subdivided on the basis of the adhesive system (etch-and-rinse or self-etch) that was used. Shrinkage stress was evaluated by placing a strain gauge at the buccal surface of the teeth. A scanning electron microscope was used to evaluate marginal adaptation in terms of a continuous margin (CM) at the gingival margin. Statistical analysis included a 2-way analysis of variance with the Holm-Sidak correction for multiple comparisons at a significance level of 0.05. The mean strain value was significantly smaller in the FRR group (185 [SD 37] µm/m) than in the UR group (295 [SD 21] µm/m). The FRR group presented with a mean CM value of 80.2% (SD 4.6%), which was significantly higher than that of the UR group, which had an overall CM value of 64.4% (SD 4.2%). There was no statistically significant difference between the adhesive subgroups with regard to strain or percentage of CM. The results showed that the incorporation of polyethylene fibers in a composite resin matrix can help to improve gingival marginal adaptation in Class II cavities.

Evaluation of Marginal Adaptation of a Self-Adhering Flowable Composite Resin Liner: A Scanning Electron Microscopic Study

Background

"Self-adhering composite resins," are claimed to eliminate the need for a separate acid etching and bonding agent application step, thus simplifying the direct restorative procedure, both regarding the technique sensitivity and the duration of treatment.

Aim

The aim of this study is to evaluate the marginal adaptation of self-adhering flowable composite (Dyad flow) in comparison to the conventional flowable composite (Tetric N-flow) under scanning electron microscope (SEM).

Settings and Design

This in vitro study was conducted on 44 extracted human maxillary premolars.

Materials and Methods

Box-only Class II cavities on the distal surface were prepared with the dimensions of 4 mm buccolingual width, 2 mm mesiodistal depth, and gingival margin at the cementoenamel junction. They were divided into two groups of 22 teeth each and were restored accordingly: Group I - Gingival floor lined with Tetric N-Flow and were restored with Tetric N-Ceram; Group II - Gingival floor lined with Dyad flow and were restored with Herculite Precis. After thermal cycling, the sectioned tooth-restoration interfaces were evaluated for the marginal adaptation under SEM at ×200 magnification.

Statistical Analysis Used

The resultant data were statistically analyzed by applying Chi-square test, using the SPSS (version 16.0) software.

Results and Conclusion

There was no statistically significant difference between the study groups regarding the marginal adaptation. The marginal adaptation of the self-adhering flowable composite when used as a liner in Class II restorations was comparable to that of the conventional flowable composite.

The Effect of Casting Ring Liner Length and Prewetting on the Marginal Adaptation and Dimensional Accuracy of Full Crown Castings

Aim:

To evaluate the effect of varying cellulose casting ring liner length and its prewetting on the marginal adaptation and dimensional accuracy of full veneer metal castings.

Materials and Methods:

The master die was milled in stainless steel to fabricate the wax pattern. Sixty wax patterns were fabricated with a uniform thickness of 1.5 mm at an occlusal surface and 1 mm axial surface, cervical width at 13.5 mm, and 10 mm cuspal height. The samples were divided into six groups (n = 10). Groups I and II samples had the full-length cellulose prewet and dry ring liner, respectively. The groups III and IV had 2 mm short prewet and dry cellulose ring liner, respectively, whereas groups V and VI were invested in 6 mm short ring liner. The wax patterns were immediately invested in phosphate bonded investment, and casting procedure was completed with nickel-chrome alloy. The castings were cleaned and mean score of measurements at four reference points for marginal adaption, casting height, and cervical width was calculated. The marginal adaption was calculated with Imaje J software, whereas the casting height and cervical width was determined using a digital scale. The data was subjected to one-way analysis of varaince and Tukey post hoc statistical analysis with Statistical Package for the Social Sciences version 20 software.

Results:

The group II had the best marginal adaption with a gap of 63.786 μm followed by group I (65.185 μm), group IV (87.740 μm), and group III (101.455 μm). A large marginal gap was observed in group V at 188.871 μm. Cuspal height was more accurate with group V (10.428 mm), group VI (10.421 mm), and group II (10.488 mm). The cervical width was approximately similar in group I, group III, and group V. Statistically significant difference was observed in Tukey post hoc analysis between group V and group VI with all the other groups with regards to marginal adaptation.

Conclusion:

The dry cellulose ring liners provided better marginal adaptation in comparison to prewet cellulose ring liners. Accurate cuspal height was obtained with shorter ring liner in comparison to full-length cellulose ring liners.

[Comparative evaluation of the marginal accuracy of single crowns fabricated computer using aided design/computer aided manufacturing methods, self-curing resin and Luxatemp]

OBJECTIVE

This study aims to compare the marginal accuracy of single crowns fabricated using self-curing resin, Luxatemp, and computer aided design/computer aided manufacturing (CAD/CAM) methods in clinical application.

METHODS

A total of 30 working dies, which were obtained from 30 clinical teeth prepared with full crown as standard, were created and made into 30 self-curing resin, Luxatemp, and CAD/CAM single crowns. The restorations were seated on the working dies, and stereomicroscope was used to observe and measure the thickness of reference points. One-way analysis of variance, which was performed using SPSS 19.0 software package, compared the marginal gap widths of self-curing resin, Luxatemp, and CAD/CAM provisional crowns.

RESULTS

The mean marginal gap widths of the fabricated self-curing resin, Luxatemp, and CAD/CAM were (179.06±33.24), (88.83±9.56), and (43.61±7.27) μm, respectively. A significant difference was observed among the three provisional crowns (P<0.05).

CONCLUSIONS

The marginal gap width of CAD/CAM provisional crown was lower than that of the self-curing resin and Luxatemp. Thus, the CAD/CAM provisional crown offers a better remediation effect in clinical application.

Marginal adaptation of newer root canal sealers to dentin: A SEM study

Aim:

This in vitro study evaluated and compared the marginal adaptation of three newer root canal sealers to root dentin.

Materials and Methods:

Thirty freshly extracted human single-rooted teeth with completely formed apices were taken. Teeth were decoronated, and root canals were instrumented. The specimens were randomly divided into three groups (n = 10) based upon the sealer used. Group 1 - teeth were obturated with epoxy resin sealer (MM-Seal). Group 2 - teeth were obturated with mineral trioxide aggregate (MTA) based sealer (MTA Fillapex), Group 3 - teeth were obturated with bioceramic sealer (EndoSequence BC sealer). Later samples were vertically sectioned using hard tissue microtome and marginal adaptation of sealers to root dentin was evaluated under coronal and apical halves using scanning electron microscopy (SEM) and marginal gap values were recorded.

Results:

The data were statistically analyzed by two-way ANOVA and Tukey's multiple post hoc test. The highest marginal gap was seen in Group 2 (apical-16680.00 nm, coronal-10796 nm) and the lowest marginal gap was observed in Group 1 (apical-599.42 nm, coronal-522.72 nm). Coronal halves showed superior adaptation compared to apical halves in all the groups under SEM.

Conclusion:

Within the limitations of this study epoxy resin-based MM-Seal showed good marginal adaptation than other materials tested.

Marginal and internal analysis of preheated dental fissure-sealing materials using optical coherence tomography

OBJECTIVES

This study aimed to evaluate the influence of pre-photoactivation temperature on the marginal and internal integrity (occurrence of voids) of fissure-sealing materials on occlusal fissures using optical coherence tomography (OCT).

METHODS

Occlusal fissures of 40 human third molars were sealed using a resin-based fissure sealant (Fluroshield) and a flowable composite (Permaflo) photoactivated at 68 °C (preheated) or at room temperature (25 °C) (n=10). After sealing, the teeth were subjected to thermocycling (500 cycles, 5-55 °C) and 14 days of pH cycling (demineralisation for 6 hours/day and remineralisation for 18 hours/day). The occlusal surfaces were scanned in a buccolingual direction, and 20 tomographic images parallel to the long axis of each tooth were obtained. Images presenting marginal gaps and internal voids were counted and statistically analysed using analysis of variance and Tukey's test (P<0.05).

RESULTS

There were statistically significant differences between materials and temperatures (P<0.01). The flowable composite had a lower percentage of gaps and internal voids than the resin-based sealant. Preheated materials had a lower percentage of gaps and internal voids than the materials at room temperature.

CONCLUSION

Therefore, preheated flowable composite provided the best marginal sealing of fissures, and internal homogeneity of the material.

Effect of tightening torque on the marginal adaptation of cement-retained implant-supported fixed dental prostheses

Background:

The final position of the abutment changes with the amount of tightening torque. This could eventually lead to loss of passivity and marginal misfit of prostheses. The aim of this study was to evaluate the effect of three different tightening torques on the marginal adaptation of 3-unit cement-retained implant-supported fixed dental prostheses (FDPs).

Materials and Methods:

Two implants (Straumann) were inserted in an acrylic block so that one of the implants was placed vertically and the other at a 15° vertical angle. A straight abutment and a 15° angulated abutment were connected to the vertically and obliquely installed implants, respectively, so that the two abutments were parallel. Then, 10 cement-retained FDPs were waxed and cast. Abutments were tightened with 10, 20, and 35 Ncm torques, respectively. Following each tightening torque, FDPs were luted on respective abutments with temporary cement. The marginal adaptation of the retainers was evaluated using stereomicroscope. FDPs were then removed from the abutments and were sectioned at the connector sites. The retainers were luted again on their respective abutments. Luting procedures and marginal adaptation measurement were repeated. Data were analyzed by ANOVA and least significant difference tests (α = 0.05). After cutting the FDP connectors, the independent samples t-test was used to compare misfit values (α = 0.05).

Results:

Following 10, 20, and 35 Ncm tightening torques, the marginal discrepancy of the retainers of FDPs significantly increased (P < 0.05). There was no significant difference between the marginal discrepancies of these two retainers (P > 0.05). The marginal gap values of angulated abutment retainers (ANRs) were significantly higher than those of the straight abutment after cutting the connectors (P = 0.026).

Conclusion:

Within the limitations of this study, the marginal misfit of cement-retained FDPs increased continuously when the tightening torque increased. After cutting the connectors, the marginal misfit of the ANRs was higher than those of the straight abutment retainers.

Comparing the Accuracy of Three Different Impression Materials in Making Duplicate Dies

BACKGROUND

Marginal adaptation is very important in cast restorations. Maladaptation leads to plaque retention, reduction of mechanical and esthetic properties. The aim of this study was to evaluate the precision of three different impression materials (including: Additional silicone [AS] and condensational silicone [CS] and polyether [PE]) for duplicating master dies.

MATERIALS AND METHODS

Three master dies from an acrylic tooth model-with supragingival and shoulder finishing line was made by using PE: Impergum, CS: Speedex, and AS: Panasil separately. The Ni-Cr copings were prepared from master dies separately. They were placed on the acrylic model and the mean marginal difference was recorded by using a stereomicroscope. Then 30 duplicate test dies were made by using the same impression materials and the marginal gaps were recorded. The comparison was done by one-way ANOVA and SPSS software (Version 13) at a significant level of 0.05.

RESULTS

The mean marginal difference of four walls from Impergum (38.56 um) was the lowest than Speedex (38.92 um) and Panasil (38.24 um). The Impergum had the highest capability in making duplicate dies (P > 0.05).

CONCLUSION

The Impergum impression material manifested the highest capability in making a better marginal adaptation of duplicate dies but further studies are needed to make a precise decision.

Marginal adaptation of mineral trioxide aggregate (MTA) to root dentin surface with orthograde/retrograde application techniques: A microcomputed tomographic analysis

Background:

Achieving a good apical seal for root canals is known to be associated with good mineral trioxide aggregate (MTA) adaptation to dentin.

Aims:

This study aims to compare the marginal adaptation of MTA with root dentin between orthograde and retrograde application techniques using microcomputed tomography (micro-CT) analysis.

Settings and Design:

Fifty-two single-rooted human teeth were divided into four equal groups: (Group 1) Retrograde MTA (RMTA), (Group 2) Orthograde MTA (OMTA), (Group 3) Etched RMTA (ERMTA), and (Group 4) Etched OMTA (EOMTA).

Materials and Methods:

For Group 1, 3-mm retrograde cavities were prepared and filled with MTA. For Group 2, the apical 6 mm of the canals were filled with MTA and sealed with sealer cement and warm gutta-percha. In Groups 3 and 4, canals were treated the same as Groups 1 and 2, respectively, except that before placing the MTA, canals were irrigated with 17% ethylenediaminetetraacetic acid (EDTA). After 48 hours, all the teeth were analyzed using a micro-CT scanner.

Statistical Analysis:

Mean dentin-MTA contact and the mean length and width of each gap was analysed using one-way analysis of variance (ANOVA). Statistical significance was set at an α level of 5%.

Results:

No significant difference in gap volumes was observed in the dentin-MTA adaptation in both orthograde and retrograde application techniques. However, significant difference in the gap volumes was observed between RMTA and ERMTA (P = 0.045). Etching significantly improved the MTA-Dentin adaptation (P < 0.05). The type of application technique did not significantly improve the dentin-MTA adaptation, instead with the use of 17% EDTA, a significant improvement could be achieved.

Conclusion:

Within the limitations of the present study, it concludes that MTA adaptation to dentin tooth structure is not significantly different between an orthograde and retrograde approach. However, the use of EDTA significantly improved the MTA-Dentin adaptation.

Effect of Blood Contamination on Marginal Adaptation and Surface Microstructure of Mineral Trioxide Aggregate: A SEM Study

Background and aims

In various clinical situations, mineral trioxide aggregate (MTA) may come into direct contact or even be mixed with blood. The aim of the present study was to evaluate the effect of exposure to blood on marginal adaptation and surface microstructure of MTA.

Materials and methods

Thirty extracted human single-rooted teeth were used. Standard root canal treatment was carried out. Root-ends were resected, and retrocavities were prepared. The teeth were randomly divided into two groups (n = 15): in group 1, the internal surface of the cavities was coated with fresh blood. Then, the cavities were filled with MTA. The roots were immersed in molds containing fresh blood. In group 2, the aforementioned procedures were performed except that synthetic tissue fluid (STF) was used instead of blood. To assess the marginal adaptation, “gap perimeter” and “maximum gap width” were measured under scanning electron microscope. The surface microstructure was also examined. Independent samples t-test and Mann-Whitney U test were used to analyze the data.

Results

Maximum gap width and gap perimeter in the blood-exposed group were significantly larger than those in the STF-exposed group (p < 0.01). In the blood-exposed group, the crystals tended to be more rounded and less angular compared with the STF-exposed group, and there was a general lack of needle-like crystals.

Conclusion

Exposure to blood during setting has a negative effect on marginal adaptation of MTA, and blood-exposed MTA has a different surface microstructure compared to STF-exposed MTA.

A 1-year clinical evaluation of fissure sealants on permanent first molars

Objective:

To evaluate and compare the retention, marginal discoloration, surface texture and anatomical form of pit and fissure sealants.

Materials and Methods:

Thirty children between the ages of 6 and 10 years, who were attending the school health program regularly, had participated in the study. A split-mouth design was used in which the two fissure sealants (Helioseal-F and Glass ionomer Fuji VII) were randomly placed in 60 matched contralateral pairs of permanent molar teeth. Sealants were rated by a single trained and calibrated examiner using mouth mirrors and probes following the US Public Health Service criteria. The sealants were evaluated at 3 months, 6 months and 1 year intervals.

Results:

The data obtained for retention, marginal discoloration, surface texture and anatomical form of pit and fissure sealants were tabulated and compared statistically using the Chi-square test of significance.

Conclusion:

The Helioseal-F sealant was better than the Glass ionomer Fuji VII sealant with respect to retention, anatomical form and surface texture. Both the materials showed similar results with respect to marginal discoloration.

Effect of calcium hydroxide premedication on the marginal adaptation of calcium-enriched mixture cement apical plug

BACKGROUND

This study was to evaluate the effects of calcium hydroxide premedication on the marginal adaptation of the calcium-enriched mixture (CEM) cement as an apical plug.

MATERIALS AND METHODS

In this in vitro study, forty single rooted teeth were prepared and apical portion of the roots were immersed in sulfuric acid to produce open apices. The teeth were divided into 2 experimental groups. In medicated group, calcium hydroxide was placed in all canals for 1 week and in non-medicated group no dressing was used. Then, a 4-mm apical plug of CEM cement was placed in canals; each root was prepared for observation using scanning electron microscope and the maximum distance between CEM cement and surrounding dentin was measured. The data were analyzed by t-test, and significance level was set at α = 0.05.

RESULTS

The mean width of gap in medicated and non-medicated groups was 158/1 μm and 147/1 μm, respectively. There was no significant difference between the two groups (P > 0.05).

CONCLUSION

Calcium hydroxide premedication had no adverse effect on the marginal adaptation of CEM cement apical plug.

Aesthetic and functionality in fixed prosthodontic: sperimental and clinical analysis of the CAD-CAM systematic 3Shape

In the last 15 years the increasing aesthetic demand, push constantly industry and the clinical to entirely look for new solutions for the realization of all-ceramic crowns, with such characteristics to be used for both anterior and posterior restorations. The most greater contribution, in such sense derives from the finished progress in the computer sector, that have allowed the application of the technologies CAD-CAM, also in dentistry (2-5, 11). These systematics have allowed us to get "automatically" structures for dental prosthesis, starting from the scanning of the die and passing for an intermediary phase of computerized planning (CAD, computer aided design), through numerical control millers (CAM, computer aided manufacturing), enslaved to calculating the electronic that drives the movement of it. The aim of this work is therefore that to analyze and to describe the systematic computerized 3SHAPE verifying the degree of precision, through the analysis of the obtainable marginal closing with the zirconia frameworks.