Bonding effectiveness of multi-step adhesive resin cements to CAD/CAM blocks: impact of thermal cycling and surface treatment methods.

BACKGROUND: To investigate the effects of thermal cycling and surface treatment methods on the bonding effectiveness of multi-step resin cements to CAD/CAM blocks. METHODS: A total of 198 slices, 66 each from CAD/CAM blocks (feldspathic ceramic: Vitablocs TriLuxe Forte, V; resin matrix ceramics (RMCs): Cerasmart, C; and Shofu Block HC, S), were obtained and randomly divided into two subgroups for etching with hydrofluoric acid (HFA) and sandblasting with Al2O3 (SB). After the surface treatments, one etched and one sandblasted sample of each CAD/CAM block was observed via SEM analysis at 500× magnification. The remaining 32 etched and 32 sandblasted samples of each CAD/CAM block were divided into two subgroups to be cemented with total-etch (TE) and self-etch (SE) resin cements. Then, half of the 16 samples in all the subgroups were subjected to aging (TC) for 5000 cycles (n = 8). The shear bond strength (SBS) of each sample was measured. Four-way analysis of variance (ANOVA) and Tukey tests were used to analyze the data (p < 0.05). RESULTS: With or without TC, the highest SBS values for V were obtained with the HFA-TE and HFA-SE interactions, respectively. C presented the highest SBS values with HFA-SE and SB-TE interactions, whereas S presented the highest SBS values with SB-TE and HFA-TE interactions. Except the SB-SE interaction, C presented lower SBS values after TC than other materials. HFA created less porosity on the C and S surfaces than V. SB visibly roughened the surfaces of all the materials but caused fractures, cracks, and damage to the surfaces. CONCLUSION: Similar SBS values can be achieved between feldspathics, RMCs, and multi-step adhesive resins with both HFA and SB treatments. However, the SBS values obtained from the SB-SE interaction may be below the recommended threshold values for all materials after TC. SB can cause distinctive cavities, fissures, and damage, especially on the surfaces of RMCs.

Influence of the preparation design on the retentive strength of resin-bonded attachments.

OBJECTIVES: The study investigated the influence of retention grooves and material thickness of the retainer wing on the retentive strength of resin-bonded attachments (RBAs). MATERIALS AND METHODS: Sixty-four extracted human molars were used. Each tooth received a preparation limited to the enamel for the retainer wings of the RBAs. The specimens were divided into eight groups, each containing eight specimens. The groups varied based on the number of conical retention grooves (0, 1, 2, or 4) and the thickness of the CoCr retainer wings (0.4 mm and 0.8 mm). Before testing the retentive strength of the RBAs, the specimens underwent 37,500 thermal cycles followed by dynamic loading of 1,200,000 cycles on the RBAs' patrices using a chewing simulator. The debonding test was conducted using a universal testing machine at a crosshead speed of 2 mm/min. RESULTS: The mean retentive strength ranged from 326 ± 96 N to 440 ± 77 N. Only a small portion of specimens (10.9%) exhibited adhesive failure, while the remainder demonstrated cohesive failure within the tooth structure. Neither the number of retention grooves, the thickness of the retainer wings, nor the size of the bonding surface significantly affected retentive strength. CONCLUSIONS: The findings suggest that reducing the number of retention grooves and the material thickness does not influence the retentive strength of RBAs. CLINICAL RELEVANCE: The retention of RBAs appears promising, supporting the clinical application of this treatment modality.

Effect of ionizing radiation on the shear bond strength of two different adhesive systems in primary teeth. in-vitro study.

BACKGROUND: Radiotherapy is a treatment modality used for head and neck cancer patients. It has a negative influence on bonding strength of adhesives. Little information is available about the effect of radiotherapy on bonding strength of adhesives in primary teeth. Therefore, this in vitro study aimed to detect the best adhesive system and ideal time to apply restorations in primary irradiated teeth regarding adhesive shear bond strength. METHODS: Dentin samples from primary teeth were randomly assigned to four groups based on restoration application time and radiation exposure, (G1: control, G2: preradiation, G3: 24 h postradiation, and G4: 6 months postradiation) with 20 samples per group. These groups were further divided into 2 subgroups according to the adhesive system used, with 10 samples per subgroup. (1) 3M™ Single Bond Universal Adhesive (SB), (2) 3M AdperSingle Bond 2 (AS). Samples were exposed to gamma radiation from a cobalt-60 machine. One shot of 60 Gy of radiation was delivered. Then samples were subjected to a shear bond strength test. The load was applied until failure and the maximum load was recorded. Numerical data are presented as mean and standard deviation values, then distributed according to Shapiro-Wilk test or Levene's test and analyzed via two-way ANOVA. The significance level was set at p < 0.05 for all tests. Statistical analysis was performed with R statistical analysis software version 4.4.1 for Windows (Team RC, R: A language and environment for statistical computing. R foundation for statistical computing, 2023). RESULTS: Compared with the AS subgroup, the SB subgroup presented significantly greater values (p < 0.001). For SB, there was no significant difference among the G1 and G4 groups (p > 0.001). However, there was a significant difference between G1, G2, and G3 (p < 0.001, P = 0.025, P = 0.265 ns respectively), and G3 presented the lowest values. For AS, there was no significant difference between groups G1 and G4 (p = < 0.001). Compared with the other groups, G3 presented a significant difference (p = 0.265 ns) and the lowest results. CONCLUSION: Restorations performed 24 h after radiation had lower bond strength than those performed six months after radiation. Regardless of the adhesive system used, SB performed better than AS in terms of the shear bond strength.

Evaluation of single-step self-etching ceramic primer and zirconia primer for bonding to zirconia-reinforced lithium silicate ceramic.

The purpose of this study was to evaluate the influence of simplified ceramic surface treatments on the microshear bond strength (µSBS) of 2 resin cements to a zirconia-reinforced lithium silicate (ZLS) material. Blocks of ZLS were sectioned to obtain a total of 90 specimens (1.5 mm thick), which were assigned to 9 different surface treatment protocols (n = 10). Either hydrofluoric acid (HF) surface conditioner or ammonium polyfluoride self-etching ceramic primer (Monobond Etch & Prime [MEP]) was used for surface treatment and then combined with different bonding strategies (Monobond N silane-based universal primer, Prosil silane coupling agent, Ambar Universal APS self-etching adhesive, and/or Signum Zirconia Bond methyl methacrylate-based bonding system [SZB]) and luting agents (Allcem or Multilink Automix dual-curing resin cement). Composite resin cylinders were bonded to ZLS with each of the cementation protocols, and the specimens were subjected to 6000 thermal cycles from 5°C to 55°C prior to the µSBS evaluation. The failure mode was analyzed with the aid of a stereoscopic loupe. Statistical analyses were performed with 1-way analysis of variance and Tukey HSD test (α = 0.05). The HF and MEP protocols resulted in significantly higher µSBS values (P < 0.001), while conditioning with SZB resulted in the lowest µSBS. Multilink Automix groups presented higher µSBS values than Allcem groups (P < 0.01). There was no statistically significant difference in the µSBS values of the MEP + Allcem groups based on whether or not an adhesive layer was applied. The failure mode was predominantly adhesive for all specimens. The results indicate that the ammonium polyfluoride-based material MEP may be used as a substitute for surface treatment with HF and silane, but the use of a zirconia primer alone is not advised for bonding to a ZLS ceramic material.

Shear bond strength of resin cement to a CAD/CAM millable alloy subjected to various surface treatments.

Resin cements are widely used to cement dental restorations; however, limited studies are available on the bond strength of these cements to computer-aided design/computer-aided manufacturing (CAD/CAM) base metal alloys. This study compared the shear bond strength between a self-etching resin cement (Panavia F 2.0) and a millable cobalt-chromium alloy (Ceramill Sintron) following various surface treatments. A total of 40 cylindrical alloy cores (6 mm in diameter × 8 mm in height) were milled and assigned to 1 of 5 groups for different surface treatments (n = 8): control (no surface treatment); sandblasting; metal primer; sandblasting + metal primer; or acid etching. Resin cement was then used to bond cylindrical composite resin specimens to the pretreated core surfaces. The specimens underwent a 1500-cycle thermocycling procedure and shear bond strength testing. The data were analyzed using 1-way analysis of variance, and P < 0.05 was considered statistically significant. The mean (SD) shear bond strength values in the different surface treatment groups were significantly different (P < 0.05): sandblasting, 16.59 (7.10) MPa; acid etching, 15.63 (2.94) MPa; sandblasting + metal primer, 13.28 (1.27) MPa; metal primer, 8.90 (2.08) MPa; and control, 8.86 (3.57) MPa. The mean differences in shear bond strength values were significant between the sandblasting and control groups (P = 0.003) and between the acid-etching and metal primer groups (P = 0.013). Surface roughening procedures--either sandblasting or acid etching of the alloy surface--improved the shear bond strength of resin cement to milled alloy surfaces. The use of metal primer between the alloy surface and resin cement did not significantly increase the bond strength.

Effectiveness of self-etching bonding systems on dentin after radiotherapy: perspectives on microtensile and microshear bond strength.

OBJECTIVE: Self-etching dental adhesives bond with dentin through chemical reactions with calcium. This study assessed bond strength (BS) using microtensile (µTBS) and microshear (µSBS) tests on sound and post-radiotherapy dentin, with dental adhesives containing different functional monomers. METHODS: Sound dentin (SD) and post-radiotherapy irradiated dentin (ID) were tested with two adhesive systems: Clearfil SE Bond (SE, 10-MDP-based) and FL Bond II (FL, containing carboxylic and phosphonic monomers with S-PRG bioactive particles). The tests occurred initially (24 h) and six months later; fracture mode was also analyzed (40x). Ninety-six human molars were randomly assigned (n = 12), and half were irradiated with a 70 Gy radiation dose. For µTBS test, teeth were bonded, restored and sectioned them into beams (0.64 mm2). The µSBS test used filled transparent cylindrical matrices with resin composite and light-cured them after dental adhesive applications. Three-way ANOVA and Tukey's test (p < 0.05) analyzed the data. RESULTS: µTBS showed a significant substrate x adhesive interaction (p < 0.001), while µSBS was significant for all factors (p = 0.006). SE and FL performed better on SD and ID, respectively, in the µTBS test. As for µSBS, SE showed higher values on ID (p < 0.05). Lower BS values occurred for SD-FL and ID-SE after six months. CONCLUSION: Dental adhesive performance varied based on substrate type and test method. FL was more stable for ID in µTBS, while SE excelled in µSBS. CLINICAL RELEVANCE: As post-radiotherapy irradiated dentin becomes more vulnerable, self-etching systems based on functional monomer and bioactive ingredients may exhibit appropriate bonding to this altered substrate.

Effects of porcelain layer thickness and luting resin cement on the opalescence properties of porcelain veneers.

BACKGROUND: When discolored teeth are repaired with porcelain veneers, the thickness of the restorations should be increased appropriately using opaque porcelain and bonded by applying opaque luting resin cement to cover discolored substrates. However, its impact on the opalescent performance has not been reported yet. PURPOSE: To analyze the effects of opacity, body porcelain layer thickness, and luting resin cement on the opalescence properties of porcelain veneer restorations for discolored teeth. METHODS: Ninety IPS d. SIGN A3 porcelain veneer specimens were prepared via powder-paste coating and sintering. Specimens were divided into three groups according to ceramic type and cement used or not: body porcelain group as control, body/opaque porcelain group and body/opaque porcelain-resin cement composite group. Each group was subdivided into three subgroups based on the thickness, 0.50, 0.75, and 1.00 mm (n = 10). Variolink N Bleach XL luting resin cement with thickness of 0.1 mm was applied to the bottoms of body/opaque porcelain specimens to produce body/opaque porcelain-resin cement composites. The opalescence (OP) values were calculated and the micromorphological characteristics were analyzed by scanning electron microscope (SEM). Statistical analysis was performed by using ANOVA test (P < 0.05). RESULTS: The opalescence values determined for the body porcelain groups with thicknesses of 0.50, 0.75, and 1.00 mm and body/opaque porcelain specimens with thicknesses of 0.45/0.05, 0.70/0.05, and 0.95/0.05 mm were 3.35 ± 0.15, 3.83 ± 0.10, 6.73 ± 0.25, 7.95 ± 0.34, 15.16 ± 0.60, and 16.49 ± 0.89, respectively. The specimens in the body and body/opaque porcelain groups exhibited significant increases in their opalescence values with increasing thickness (P = 0.00). The opalescence values of the specimens increased significantly with the addition of a 0.05 mm opaque porcelain layer (P = 0.00). The opalescence values of the composites containing body/opaque porcelain layers with thicknesses of 0.45/0.05, 0.70/0.05, and 0.95/0.05 mm and luting resin cement were 9.46 ± 0.17, 16.47 ± 0.15, and 18.38 ± 0.47, respectively. The opalescence values of the composite specimens increased significantly with an increase in the thickness of the porcelain layer(P = 0.00). CONCLUSIONS: The opaque porcelain layer and opaque resin cement can significantly improve the opalescence properties of porcelain laminate veneers for discolored teeth, but the opalescence performance is still poor than natural teeth. The body porcelain only contributes to opalescence within a certain thickness range.

A Novel Graphite Fluoride/Bioactive Glass-containing Orthodontic Primer with Antibacterial and Remineralization Properties: An In-vitro Study.

PURPOSE: This study aimed to develop a novel orthodontic primer that incorporated graphite fluoride (GF) and Bioactive glass (BAG) and to investigate its cell viability, bonding strength, and enamel damage, as well as its antibacterial and remineralization properties. MATERIALS AND METHODS: Nine groups were prepared by adding different concentrations of GF (1, 2, and 4 wt.%) and BAG (1, 3, and 5 wt.%) to Transbond™ XT orthodontic primer. The prepared primers were compared to the control primer in terms of cell viability, shear bond strength (SBS), adhesive remnant index (ARI), enamel damage index (EDI), and antibacterial test. Then, the groups with better antibacterial properties (GFBAG 1-1, GFBAG 4-1, GFBAG 4-3, GFBAG 4-5) were evaluated for the remineralization properties. RESULTS: All the prepared orthodontic primers with different concentrations of GF/BAG revealed acceptable cell viability levels, with comparable SBS and ARI values to the control primer (p>0.05). Simultaneously, the EDI was reduced, while the antibacterial properties were significantly enhanced when compared to the control group (p0.05). The result of remineralization properties revealed that the selected groups had significantly higher remineralization ability than the control group; this was most pronounced in the GFBAG 4-3 group. CONCLUSIONS: All the prepared GF/BAG orthodontic primers are biologically safe with adequate SBS, ARI, and EDI values for clinical application with enhanced antibacterial properties. The GFBAG 4-3 experimental primer reveals the best antibacterial and remineralization properties which require further in-vitro and in-vivo investigations as a preventive measure of white spot lesions.

Shear bond strength between dental adhesive systems and an experimental niobium-based implant material.

This study aimed to investigate adhesive shear bond strength (SBS) on an ultrafine-grained niobium alloy (UFG-Nb) that is a potential dental implant material. SBS of three adhesive systems combined with three composites to UFG-Nb was compared to corresponding SBS to Ti-6Al-4V and to zirconia. Specimens of the substrates UFG-Nb, Ti-6Al-4V and zirconia with plane surfaces were sandblasted with Al2O3, cleaned and dried. Three adhesive systems (Futurabond U, Futurabond M + , Futurabond M + DCA; all VOCO GmbH, Cuxhaven, Germany) were applied each on specimens of each substrate and light cured. One composite (BifixSE, BifixQM, GrandioSO; all VOCO GmbH) was applied and light cured resulting in 27 groups (n = 10) for all substrate-adhesive-composite-combinations. SBS was measured after 24 h of storage. To simulate aging equally prepared specimens underwent 5000 thermocycles before SBS measurement. There was no significant difference in SBS within the non-aged groups. Among the artificially aged groups, GrandioSO-groups showed a greater variance of SBS than the other composites. All significant differences of corresponding UFG-Nb-, Ti-6Al-4V- and zirconia-groups with same adhesive-composite-combination (ACC) were observed between UFG-Nb and zirconia or Ti-6Al-4V and zirconia but never between the two metallic substrates. The similarity between these materials might show in their adhesive bonding behavior. As there were no differences comparing corresponding groups prior to and after artificial aging, it can be concluded that aging does not affect SBS to UFG-Nb, Ti-6Al-4V and zirconia using the tested ACCs. Adhesive bonding of established ACCs to UFG-Nb is possible resulting in SBS comparable to those on Ti-6Al-4V and zirconia surfaces.

Influence of curing mode and aging on the bonding performance of universal adhesives in coronal and root dentin.

BACKGROUND: This study aims to evaluate the microtensile bond strength (µTBS) of different resin composite restorations bonded to mid-coronal dentin and proximal root dentin using light-cured, chemical-cured, and dual-cured adhesives immediately and after aging. Nanoleakage and degree of cure were also assessed. METHODS: Eighty-four molars were divided into mid-coronal dentin and proximal root dentin. Each group was further subdivided into three subgroups based on the restorative systems used, which involved the utilization of light-cured, chemical-cured, and dual-cured adhesives. Half of the specimens underwent µTBS testing after 24 h, while the other half after aging. Representative specimens were analyzed for nanoleakage. The degree of cure of the tested adhesive systems was also assessed. RESULTS: Aging showed a significant negative effect on µTBS results and led to increased nanoleakage (p < 0.001). Furthermore, in all subgroups, the µTBS values of proximal root dentin were lower compared to mid-coronal dentin, except in the aged subgroup for the system utilizing the dual-cured adhesive. The restorative systems with chemical and dual-cured adhesives demonstrated comparable bonding properties. However, the system with the light-cured adhesive exhibited the worst bonding properties after aging when bonded to proximal root dentin and cured at a large distance (p < 0.05). CONCLUSIONS: All tested restorative systems were negatively affected by aging, and the regional dentin had variable effects on the bonding properties. Clinicians should exercise caution when using the tested light-cured adhesive in areas where the curing distance exceeds 3 mm.

Periodontal Evaluation for a New Alkasite Restorative Material in Noncarious Cervical Lesions: A Randomized-Controlled Clinical Trial.

OBJECTIVES: This study aims to evaluate the periodontal condition adjacent to Cention N (CN) restorations applied for noncarious cervical lesions (NCCL) compared with resin-modified glass ionomer cement (RM-GIC) restorations in terms of plaque accumulation, attachment loss, and gingival inflammation. MATERIALS AND METHODS: This is a double-blind split-mouth three-armed randomized-controlled clinical trial. The study arms are RM-GIC (FUJI II LC), CN + adhesive system, and CN + retentive groove. The study included 25 restorations per arm. Follow-ups were performed at 1 week, 3, 6, and 9 months after the application of the restorations. The periodontal condition was evaluated using the plaque index (PI), the bleeding on probing index (BOP), and the probing depth (PD). Appropriate tests were used to perform statistical analyses (α = 0.05). RESULTS: There was no significant difference between Cention N and RM-GIC regarding the studied variables. However, after the application of the restorations, it was noted that the PI and the PD mean values increased. The average increase after 9 months was 0.06 and 0.34 for PI and PD, respectively, with that of PD being significant. It was also noted that the percentage of positive BOP sites increased at the 1-week follow-up for all study groups and afterward dropped to near preintervention values at the 3-month and later follow-ups. CONCLUSIONS: The two ion-releasing materials Cention N and RM-GIC have a comparable and clinically acceptable effect on the gingival tissue when restoring NCCLs. The combined effect of the gingival retraction cord and the rubber dam clamp on the periodontal tissues might be more important to consider, especially in relation to the probing depth. Future long-term studies are needed to evaluate the effect of Cention N on the subgingival biofilm in comparison with nonion-releasing restorative materials, and subsequently, its effect on gingival inflammation. CLINICAL TRIAL REGISTRATION: This clinical trial was registered in clinicaltrial.gov clinical registry under protocol #NCT05593159.

Masking ability of CAD-CAM resin-matrix ceramics with different translucencies and thicknesses combined with four cement shades against varying background colors when facing veneer restorations.

BACKGROUND: To evaluate the comprehensive effect of translucency, thickness, cement shades, and background color on the masking ability of resin-matrix ceramic veneer restorations. METHODS: Resin-matrix ceramic specimens with 2 translucencies (LT, HT) and 3 thicknesses (0.5, 1.0, and 1.5 mm) were made of Upcera Hyramic (A2 shade). Cement specimens were made of Variolink N in 4 shades (yellow, white, transparent, and bleach XL). Five background specimens were made of IPS Natural Die Material in 5 shades (ND1, ND2, ND3, ND4, and ND5). Color coordinates of 120 subgroups (n = 5) of combined specimens composed of different ceramic, cement, and background specimens were obtained using a spectroradiometer. Color difference (ΔE00) compared with a 4-mm thick specimen of LT and HT ceramics was calculated and four-way ANOVA was used for statistical analysis (α = 0.05). RESULTS: Translucency, thickness, cement shade, background color, and their interaction had significant effects on ΔE00 (p < 0.001). ΔE00 values of HT groups were always higher than that of LT groups and were greater than 1.8 against all background colors. ΔE00 values of LT groups could be achieved to be less than 1.8 with appropriate thickness and cement shade. ΔE00 value decreased with increasing ceramic thickness. The effect of cement shade on ΔE00 had no obvious regularity, but ΔE00 values of bleach XL cement shade group were always lower than other cement shade groups under ND3 and ND5 background color. CONCLUSIONS: The masking ability of CAD-CAM resin-matrix ceramics can be simultaneously affected by translucency, thickness, cement shade, and background color. Resin-matrix ceramics with low translucency has a better masking ability than that with high translucency. The masking ability of CAD-CAM resin-matrix ceramics increase with increasing thickness. Cement shade has less impact on the final color of resin-matrix ceramic restorations.

Morphological Analysis and Bond Strength to Root Canal Dentin of Endodontically Treated and Retreated Teeth: An Ex Vivo Study.

PURPOSE: To assess the bond strength and the hybrid layer (HL) micro-morphological characteristics at the cement-dentin interface (CD-i) between root canal walls and two adhesive resin cements [self-etch (SERc) and self-adhesive (SARc)] in root-canal-treated (RCT) and naturally aged retreated teeth (RCR-T). MATERIALS AND METHODS: Vital (n = 16) and RCT (n = 16) teeth were, respectively, endodontically treated or retreated. Fiber posts were luted either with SERc (Clearfil Universal Bond Quick + DC Core Plus) or SARc (iCEM). Samples were then sectioned into 1 mm thick slices perpendicular to the fiber post and submitted to push-out bond strength test. Vital (n = 4) and RCT (n = 4) first maxillary molars were also selected and prepared to evaluate CD-i morphology through confocal laser scanning microscopy (CLSM). Three-way analysis of variance (ANOVA) and Tukey post-hoc tests were assessed to statistically analyze the obtained data (p 0.05). RESULTS: Bond strength was significantly jeopardized in retreated teeth and in the root apical half, while the cements had no significant influence. Most failures occurred between dentin and resin cement. HL thickness was also hindered in retreated teeth. iCEM produced a thinner HL compared to SERc. Resin tag formation was significantly hampered in the root apical half. CONCLUSIONS: SARc performed as well as SERc on aged RCT radicular dentin. Clinicians can rely on simplified one-step luting systems when adhesion is required in unfavorable substrates such as the root canal post space of aged RCT teeth.

A randomized controlled clinical trial of the performance of three bioactive endodontic cements in primary molar teeth diagnosed with reversible pulpitis: 1-year follow-up study.

OBJECTIVES: The objective of this clinical trial was to evaluate and compare the clinical and radiographic successes of three bioactive endodontic cements (BEC) including novel portland cement-based material releasing fluoride, resin-modified silicate glass cement, and pure tricalcium silicate-based cement-in the treatment of primary molars diagnosed with reversible pulpitis via indirect pulp capping. METHODS: Eighty-six (86) participants with previously untreated first and second primary molars were included in this study. The teeth were randomly allocated into three groups: pure tricalcium silicate-based cement, resin-modified silicate glass cement, and novel portland cement-based material releasing fluoride. Cavities were capped with the assigned cement after caries excavation using standard protocols. The teeth that underwent treatment were restored using glass ionomer cement and composite resin. Clinical and radiographic evaluations were performed at 1, 6, and 12 months. The data were analyzed using Pearson chi-square, Kruskal-Wallis H and Z test (P = 0.05). RESULTS: The success rate was 88 % (n = 25) in the pure tricalcium silicate-based cement group, 88.5 % (n = 26) in the resin-modified silicate glass cement group, and 100 % (n = 25) in the novel portland cement-based material releasing fluoride group. The differences at the 1st, 6th, and 12th month follow-up visits were not statistically significant among the groups (P > 0.05). No difference was found between the integrity of the resin composite restorations overlying pure tricalcium silicate-based cement, resin-modified silicate glass cement, and novel portland cement-based material releasing fluoride according to the USPHS criteria. CONCLUSIONS: Novel portland cement-based material releasing fluoride can be considered an alternative for preserving the tooth, as it showed a high success rate in treating primary molars diagnosed with reversible pulpitis via indirect pulp capping. CLINICAL SIGNIFICANCE: Novel Portland cement-based material releasing fluoride could be beneficial in the treatment of primary molars diagnosed with reversible pulpitis via indirect pulp capping.

Characterization of 3D printed composite for final dental restorations.

OBJECTIVES: This study evaluated the mechanical, optical, microstructural, surface, and adhesive behavior of a 3D printing resin comparing it with a machinable resin composite. MATERIALS AND METHODS: Specimens of different sizes and shapes were either printed (Vitality, Smart Dent) or machinable (Grandio Blocs, Voco GmbH) resin composites with similar composition were prepared. Surface and mechanical characterization were performed with Knoop hardness, flexural strength (three-point-bending), and elastic modulus tests. The wear of the tested materials was evaluated against steatite antagonists. The optical properties stability (color change, ΔE00, and translucency, TP00) were observed after staining in red wine. In addition, the bond strength of the resin composites to two resin cement protocols were investigated with microshear bond strength tests at baseline and after thermocycling. Scanning electron microscope (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) was used for microstructural and chemical characterization. Statistical analyses were performed with t- and ANOVA tests. RESULTS: Hardness values (132.76 (16.32) KH- Machinable and 35.87 (2.78) KH - Printed), flexural strength (172.17 (26.99) MPa - Machinable and 88.69 (8.39) MPa - Printed), color and translucency change (1.86 (0.31)/0.06 - Machinable and 3.73 (0.36)/9,16- Printed), and wear depth (24.97 mm (3.60)- Machinable and 7.16 mm (2.84) - Printed) were statistically different. Average Regarding bond strength, mean values (MPa) for non-aged and aged groups were respectively 21.76 (6.64) / 31.9 (12.66) for Bifix cement (Voco GmbH, Cuxhaven, Germany) and 26.75 (5.14) / 24.36 (6.85) for Variolink cement (Ivoclar Vivadent, Schaan, Liechtenstein) in Printed and 17.79 (3.89) / 9.01 (3.36) ) for Bifix cement and 22.09 (6.55) / 11.01 (3.77) for Variolink cement in Machinable materials. The material and aging factors did affect bond strength but the cement factor did not (p = 0.202). No statistical differences were observed for mean roughness (Ra) between materials. The better dispersion and larger size of the inorganic particles in the Machinable resin were contrasted with the clustered smaller particles of printed resin, under SEM. CONCLUSIONS: The mechanical properties and color stability of the machinable resin were superior to those of the printed resin, probably due to the greater amount and dispersion of inorganic particles in the Mach resin, but bond strength after aging was stronger and more stable in the printed resin. CLINICAL RELEVANCE: 3D-printed resin composites with similar compositions to machinable resin composites do not necessarily exhibit the same properties, which can impact clinical performance. Understanding these differences can assist manufacturers in improving their materials and help clinicians distinguish between materials appropriate for provisional and final restorations.

Comparative evaluation of surface roughness and bacterial adhesion on two bioactive cements: an in-vitro study.

BACKGROUND: Dental restorative materials are recognized as artificial niches that facilitate the adherence and accumulation of oral microorganisms. To mitigate oral diseases and extend the lifespan of restorations, it is advantageous to use dental materials that exhibit low susceptibility to bacterial adhesion. OBJECTIVE: To evaluate and compare bacterial adhesion on two bioactive restorative materials, a glass hybrid restorative, and an alkasite with a nanohybrid resin composite as a positive control. The secondary objectives were to compare the surface roughness (SR) of the materials and determine the correlation between the bacterial adhesion and the SR. MATERIALS AND METHODS: The samples consisted of 33 polished discs of each material: Group A: Tetric® N-Ceram (nanohybrid resin composite), Group B: Equia Forte™ HT Fil (glass hybrid restorative) and Group C: Cention N® (alkasite). Streptococcus mutans cultures were inoculated and after 24-hours of incubation, bacterial adhesion was measured by measuring optical density (OD) and number of colony forming units (CFUs). After 96-hours incubation, the bacterial cell count was determined using scanning electron microscopy (SEM). SR was assessed using surface profilometer. RESULTS: Alkasite had significantly lower OD and CFUs (p < 0.001 and p = 0.015 respectively). According to the SEM analysis, the glass hybrid restorative had lower mean bacterial cell count with no significant difference between the groups. The nanohybrid composite had the smoothest surface that was significantly lower than the alkasite and glass hybrid restorative (p = 0.002). None of the groups demonstrated a correlation between bacterial adhesion and SR. CONCLUSION: Alkasite impedes bacterial adhesion better than the glass hybrid restorative and nanohybrid composite, while smoother surfaces are achieved with the nanohybrid composite.

Fiber post cemented using different adhesive strategies to root canal dentin obturated with calcium silicate-based sealer.

BACKGROUND: Calcium silicate-based sealer has favorable properties for root canal filling, including hydroxyapatite formation during the setting process. However, this process can cause difficulty during post space preparation when the sealer is set. Additionally, the remaining sealer could interfere with the bond strength of fiber post to root canal dentin. The different adhesive strategies and fiber post cementation time may affect the bond strength of the fiber post. Thus, the objective of this study was to evaluate the effect of etching modes of Scotchbond™ Universal Plus adhesive and post cementation time on the push-out bond strength of a fiber post cemented in root canals obturated with calcium silicate-based sealer. METHODS: Fifty-four teeth were randomly allocated to 6 groups (n = 9) based on etching modes: self-etch (SE) or etch-and-rinse (ER); post space preparation and cementation time: immediate (Im) or 7-day delayed (De): Im-Im, Im-De, and De-De. The root canals were obturated with calcium silicate-based sealer and the post space preparation was performed. The fiber post was cemented using RelyX™ Universal resin cement according to each group's design. For the push-out bond strength test, 1-mm slices of the coronal, middle, and apical regions were tested using a universal testing machine. The failure mode analysis was determined using a stereomicroscope. The data was analyzed with three-way analysis of variance. RESULTS: No negative effects of etching modes, post space preparation or cementation time on push-out bond strength were detected (p > 0.05). Additionally, the root canal region also did not significantly affect the bond strength (p > 0.05). CONCLUSION: No significant differences were observed between the etching modes, post space preparation and cementation time and among root canal regions. CLINICAL RELEVANCE: The different etching modes of adhesive and post cementation time did not affect the bond strength of fiber post in calcium silicate filled-root canal.

Influence of light-polymerizing units and zirconia on the physical, chemical and biological properties of self-adhesive resin cements.

BACKGROUND: Self-adhesive resin cements (SARCs) are widely used for fixed prostheses, but incomplete cleaning near the gingival margin can cause inflammation. However, the factors influencing cement properties and the biological response of gingival fibroblasts to cement eluates are not well understood. This study examines the impact of two light-polymerizing units (LPUs) on the physical and chemical properties of two SARCs under simulated clinical conditions, as well as the subsequent response of human gingival fibroblasts (hGFs) to these eluates. METHODS: Dental cement discs of SARCs were polymerized using Kerr DemiPlus and 3 M Elipar DeepCure-S LED LPUs with or without a 2-mm thick zirconia screen. Physical properties (microhardness, surface roughness, residual monomers) were evaluated. hGFs' cell viability, wound healing potency, and gene expression were assessed. RESULTS: Both Maxcem and RelyX exhibited reduced microhardness and increased surface roughness when polymerized through zirconia or with DemiPlus LPU. Higher residual monomers (HEMA and GDMA in Maxcem; TEGDMA in RelyX) concentration was observed with DemiPlus and zirconia polymerization. Maxcem polymerized with DemiPlus exhibited lower cell viability, impaired healing, and altered gene expression in hGFs compared to those polymerized with Elipar LPU. Gene expression changes included downregulated NRF2 and HO-1 and upregulated CCR-3. CONCLUSIONS: Light-polymerizing Maxcem through zirconia with DemiPlus LPU compromised SARCs' properties, leading to higher residual monomers and negatively impacting hGFs' viability, healing, and gene expression. Careful material selection and polymerization techniques are crucial to minimize adverse effects on surrounding tissues. CLINICAL SIGNIFICANCE: Clinicians should exercise caution when using LPUs and SARCs, especially when polymerizing through zirconia. This will help optimize the physical and chemical properties of SARCs and minimize potential adverse effects on the surrounding gingival soft tissues.

Comprehensive clinical evaluation of indirect and direct bonding techniques in orthodontic treatment: a single-centre, open-label, quasi-randomized controlled clinical trial.

BACKGROUND: Few prospective investigations have compared direct and indirect techniques through comprehensive and detailed clinical evaluations, considering the impact of all factors. OBJECTIVES: This study aimed to compare and evaluate direct and indirect bonding methods at a single institution and to clarify the selection criteria for the bonding method. MATERIALS AND METHODS: This single-centre, quasi-randomized controlled clinical trial included 153 patients who required fixed orthodontic treatment. They were randomly divided into indirect and direct binding groups by the project lead (K.K.), who was blinded to all clinical data, and performed the allocation using medical record numbers. The chair time for bracket bonding, discomfort during bracket bonding, oral hygiene after bonding, number of bracket failures, number of intentional bracket reattachments, post-treatment occlusal index, and total treatment time were assessed. Outcomes were compared using a two-sample t-test or Mann-Whitney U test (P < .05). RESULTS: Fifty-eight patients were included in the indirect bonding group (20 male, 38 female; mean age: 20.63 ±â€…5.69 years) and 66 (14 male, 52 female; mean age: 23.17 ±â€…8.83 years) in the direct bonding group. Compared to the direct bonding group, the indirect bonding group had shorter chair time (P < .001), a shorter total treatment period (P < .01), and a better final occlusal relationship (P < .001). The number of bracket detachments was higher (P < .001) in the indirect bonding group, but the number of intentional reattachments was lower (P < .001). CONCLUSION: Indirect bonding may improve the efficiency of orthodontic treatment. HARMS: No harm was observed during the study. TRIAL REGISTRATION NUMBER: This trial was approved by the Ethics Review Committee of Okayama University (approval number: d10001), UMIN registration number 000022182.

Investigation of the cytotoxic effect of current dentine bonding agents on human dental pulp cells.

BACKGROUND: An ideal aesthetic restorative material should be attached to the tooth tissues by adhesion, have a smooth surface as possible, should not cause toxic reactions in the pulp and discoloration and microleakage. This study aims at comparatively assess the cytotoxicity of current adhesive systems on human dental pulp cells. MATERIALS AND METHODS: The adequate density of human pulp cells was observed from the ready cell line. The passaging was performed and the 3rd passage cells were selected. Adhesive systems and MTA were used on the cultures. Trypan blue staining was conducted on the cells at the 1st, 2nd, 3rd days and a count of live and dead cells using a light microscope. The dead cells whose membrane integrity was impaired by staining with trypan blue and the viability rate was determined using live and dead cell numbers. Data analysis was performed using IBM SPSS Statistics 22. RESULTS: A significant difference in vialibity rates between adhesive systems was observed on the first day. No significant statistical differences were observed on the 2nd and 3rd days (p < 0.05). CONCLUSION: Futurabond M showed similar biocompatibility with MTA on human pulp cells and it can be applied in cavities with 1-1.5 mm hard tissue between pulp and dentine.