American journal of dentistry最新文献

Purpose: To evaluate the laboratory potential secondary caries reduction of restorative dental materials.

Methods: 20 maxillary molars received Class V cavities on both buccal and lingual surfaces with enamel and root surface margins adjacent to the restorations. The teeth were randomly assigned into four groups with five teeth per group. The treatment groups were: (1) Filtek Bulk Fil (negative control); (2) Equia Forte glass-ionomer (positive control); (3) Beautifil giomer (fluoride releasing); and (4) Activa Restorative (fluoride releasing). All teeth were restored following the manufacturers' instructions. All teeth received 10,000 thermal cycles followed by immersion in a demineralizing solution to produce artificial caries-like lesions. Polarized light microscope evaluation was performed on longitudinal sections (30 enamel lesions per the ten Cate method, and 30 root surface lesions per group). Lesion depth and wall lesions for both enamel and root surface adjacent to the restorations were evaluated using ANOVA and Duncan's Multiple Range test (P< 0.05).

Results: On enamel surfaces, a significantly increased difference was seen with Filtek Bulk Fil compared with the other restorative materials for primary surface lesion depths and wall lesion frequency (P< 0.05: ANOVA and Duncan's Multiple Range Test). Significant difference was found with Activa Restorative (significantly less) compared with Equia Forte glass ionomer and Beautifil Giomer for primary surface lesion depths and wall lesion frequency (P< 0.05: ANOVA and Duncan's Multiple Range Test). On root surfaces, a significantly increased difference was recorded with Filtek Bulk Fil compared with the other restorative materials for primary surface lesion depths and wall lesion frequency (P< 0.05: ANOVA and Duncan's Multiple Range Test). A significant difference was found with Activa Restorative (significantly less) compared with Equia Forte glass ionomer and Beautifil giomer for primary surface lesion depths and wall lesion frequency (P< 0.05: ANOVA and Duncan's Multiple Range Test).

Clinical significance: Both lesion depth and frequency of wall lesions in the enamel and root surfaces adjacent to the restorations in all treatment groups were significantly (P< 0.05) reduced compared with the control group for a enamel and root cavosurface wall lesions, which may imply effect of fluoride release from fluoride-containing restorative materials vs non-fluoride containing ones. Activa Restorative, compared to Equia Forte glass ionomer and Beautifil giomer, showed statistically significantly less enamel and root surface wall lesions.

Purpose: To investigate the fracture strength of occluso-proximal restorations in primary teeth using different commercial brands of flowable bulk-fill resin composites (as an intermediate layer or entire restoration) in comparison with conventional resin composite (incremental technique).

Methods: Two standardized occluso-proximal cavities (4 mm cervico-occlusal height, 4 mm bucco-lingual/palatal width and 2 mm disto-mesial width) were prepared in 90 sound primary molars. The teeth were randomly divided into nine groups (n=10) according to the resin composites (Z350 XT, Filtek Bulk-Fill Flowable, Beautifil II, Beautifil Bulk Flowable, Opallis, Opus Bulk Fill Plus), number of increments of flowable bulk-fill resin composite [2 mm (intermediate layer) or 4 mm (entire restoration)] and control - conventional resin composite (incremental technique). All restored teeth were subjected to pH cycling prior to fracture strength test. The mean fracture strength values were analyzed using one-way ANOVA and Tukey's post-hoc tests. (α= 5%). The failure mode of each specimen was categorized as adhesive, cohesive, or mixed and analyzed descriptively.

Results: No significant difference in fracture strength was found among the groups (P= 1.00). Mixed failures prevailed (range of 60-90%) in all groups.

Clinical significance: Based on fracture strength data, contemporary flowable bulk-fill resin composites that have high filler content may be an option for restoring entire conservative occluso-proximal cavities in primary molars, regardless of the commercial brand, promoting the simplification of restorative procedures in pediatric dental practice.

Purpose: To evaluate if gCN (g-C₃N₄) quantum dot (QD) complexes destruct oral cancer cells in vitro in 100 µM H₂O₂ and laser irradiation conditions.

Methods: gCN complexes were synthesized using polymer, precursor melamine, metal, and photosensitizer. Cell viability tests were performed using cancer and normal cells. To evaluate ROS production by gCN complexes, MB degradation test and RNO-ID assay were performed. Oxygen generation in the test solutions was also evaluated under 100 µM H₂O₂ and laser irradiation conditions.

Results: Upon the gCN complexes tested, PGC-Ce6 [pvp-(gCN-Cu)-Ce6] destructed over 83% of initial in vitro cancer cells in 100 µM H₂O₂ and laser irradiation conditions, while approximately 88% of normal cells were viable under no laser irradiation. MB solution was greatly degraded (bleached) by PGC-Ce6. Oxygen was generated by PGC-Ce6 in 100 µM H₂O₂ and laser irradiation conditions, yet the amount was little (0.6 mg/L). Absorbance of RNO-ID solution was much decreased with increasing reaction time of PGC-Ce6 in 100 µM H₂O₂ and laser irradiation conditions.

Clinical significance: g-C₃N₄ complex (PGC-Ce6) destroyed over 83% of initial in vitro cancer cells in 100 µM H₂O₂ and laser irradiation conditions. The result suggests high potential for clinical tumor treatment of PGC-Ce6 using laser irradiation though further investigation is required.

Purpose: To investigate the changes in the radiopacity values of resin cements, resin composites, and flowable resin composites used for bonding after preheating.

Methods: Three different materials (Panavia V5, Clearfil Majesty Posterior, and Clearfil Majesty Flow) were evaluated. For each material, five specimens with 0.5 mm and 1 mm thickness were prepared. Additionally, the two resin composites were preheated at 55°C and 68°C for 15 and 30 minutes, resulting in a total of 22 groups and 110 specimens. Periapical radiographs of the specimens were obtained. During radiograph acquisition, 0.5 mm and 1 mm human tooth sections, along with aluminum step wedges, were placed adjacent to the specimens. Mean Gray Value measurements were conducted using ImageJ software to determine aluminum equivalence. After 21 days at 37°C, the radiopacity values of the specimens were remeasured and compared with the initial values.

Results: The radiopacity values of the 1 mm-thick specimens were significantly higher than those of the 0.5 mm-thick specimens (P= 0.001). Preheating the resin composites generally led to an increase in radiopacity. A Pearson correlation test was performed to assess the relationship between heating temperature and radiopacity, yielding a correlation coefficient of r= 0.249. This result indicates a weak but statistically significant correlation between temperature and radiopacity (P= 0.026). An increase in radiopacity values was observed with prolonged heating. Clearfil Majesty Posterior exhibited a steady increase in radiopacity with increasing heating time and temperature. However, Clearfil Majesty Flow showed a decrease in radiopacity values after prolonged heating at 68°C (P= 0.150). Following the artificial aging process, a statistically significant decrease in the radiopacity values of the samples was detected (P= 0.003).

Clinical significance: In recent years, preheating adhesive materials to enhance adhesion between different substrates has gained popularity. Preheating may also affect radiopacity values. Given the potential chemical changes induced by heat treatment, it is essential to evaluate heat-treated materials comprehensively across multiple parameters. Furthermore, the aging process can influence the radiopacity values of materials. Therefore, careful material selection is crucial for the long-term follow-up of restorations.

Purpose: To evaluate the effects of different whitening toothpastes on bovine tooth enamel during at-home bleaching with 10% carbamide peroxide.

Methods: Enamel-dentin specimens were randomly assigned to five groups based on the toothpaste used: distilled water (DW), regular toothpaste (RT), whitening toothpaste with abrasive agents (WT), whitening toothpaste with abrasive and chemical agents (PT), and whitening toothpaste with abrasive, chemical, and bleaching agents (HP). All specimens underwent brushing and bleaching procedures for 14 days. Surface microhardness (SMH), surface roughness (Ra), and color parameters (ΔL*, Δa*, Δb*, ΔE*ab, and ΔE*₀₀) were analyzed. Data were statistically evaluated using two-way ANOVA followed by Tukey's post-hoc test (α= 0.05).

Results: All groups showed a significant reduction in SMH and an increase in Ra between the initial and final timepoints (P< 0.05). At the final evaluation, PT showed intermediate values, while HP presented the highest SMH, differing significantly from all other groups. For surface roughness, the WT group exhibited the highest Ra, while RT had the lowest values among the toothpaste groups. No significant differences were observed for ΔE*ab and ΔE*₀₀ between groups (P> 0.05). Whitening toothpastes used concomitantly with at-home dental bleaching do not enhance the whitening effectiveness; however, they may cause changes to the enamel surface.

Clinical significance: Whitening toothpastes used concomitantly with at-home bleaching do not enhance whitening effectiveness but may negatively affect enamel surface properties by increasing roughness and reducing microhardness.

Purpose: To evaluate the microtensile bond strength (µTBS) of adhesive resins after cleaning the calcium silicate-based root canal sealer (CSBS) removed from the dentin with different solvents and cleaners.

Methods: 70 human molar teeth were randomly divided into seven main groups. All surfaces were rinsed with 2% NaOCl and 17% EDTA and contaminated with CSBS. Solvents or cleaners used were as follows: no sealer, no solvent, chloroform, ethanol, Endosolv E, phosphoric acid, and hydrofluoric acid. All groups were divided into Subgroup U (universal adhesive) and Subgroup S (two-step self-etching adhesive). Composite build-ups were made with a nanocomposite. Dentin-composite sticks were obtained from each tooth (n=11). µTBS testing was performed, and stereomicroscopic and scanning electron microscopic (SEM) analyses were performed.

Results: The µTBS values of Endosolv E were statistically the highest among the groups (P< 0.05). When comparing the adhesive systems, the µTBS values of the self-etching adhesive groups were significantly higher in no sealer and ethanol groups. Endosolv E produced a better adhesive-dentin bond than the other groups. The self-etching adhesive showed a better bond regardless of the solvent used. Endosolv E and self-etch adhesive may be suitable for adhesive procedures after endodontic treatment with CSBS.

Clinical significance: Endosolv E, in conjunction with a self-etching adhesive, may prove an efficacious method for cleaning residual sealer and adhesive procedures following endodontic treatment with CSBC.

Purpose: To evaluate the effect of water and chlorhexidine (CHX) jet flossing on the mass, water sorption (WSP), and water solubility (WSL) of different types of resin composite cement (light-cure, chemical-cure, and dual-cure).

Methods: Three commercially available adhesive resin cements, light-, chemical-, and dual-cure were evaluated. For each resin cement type, a total of 50 disc-shaped specimens (4x2 mm) were made. Each cement group was then divided into five experimental subgroups (10 per subgroup), based on the treatment protocol: Control, stored in distilled water (DW) with no jet flossing; 50 psi water; 75 psi water; 50 psi CHX (0.12%); and 75 psi CHX (0.12%) jet flossing subgroups. The irrigant (DW or 0.12% CHX) was applied at (50 or 75) psi for 30 minutes, simulating 5 years of daily 1-minute flossing. Mass changes, WSP, and WSL were evaluated after treatment. One-way ANOVA was used to compare the results.

Results: The light-cure cement showed the highest mass stability with minimal changes (≤ 0.53%) across all treatment groups, along with lowest WSP (0.0132% ± 0.0027) and WSL (-0.01328% ± 0.00414). The chemical-cure cement exhibited the poorest stability, with significant mass increases (up to +1.45% under 75 psi CHX) associated with negative WSP (-0.0290% ± 0.00276%) and the highest WSL (-0.688% ± 0.00495%). While dual-cure cement displayed intermediate mass changes, with slight variability (+0.65%) under 75 psi CHX, that was linked with the highest WSP (0.0878% ± 0.0058) and moderate WSL (0.135% ± 0.00581%). 50 psi water flossing caused significant mass differences (P= 0.004, η²= 0.412), with light-cure cement showing the lowest dry mass. Similarly, 75 psi CHX flossing caused significant mass differences (P =0.047, η²= 0.252), in the post-floss wet state. While both 50 psi CHX and 75 psi water flossing showed no significant mass differences.

Clinical significance: Light-cure cement exhibited superior mass stability and resistance to water sorption and solubility, under simulated jet flossing conditions, compared to chemical- and dual-cure cements. However, patients with crowns should avoid sustained high-pressure flossing, especially with chlorhexidine, to preserve cement integrity.

Purpose: To evaluate the effect of various pigments with white or blue coloring properties, which could be applied to bleached enamel surfaces, on the tooth color.

Methods: Bovine teeth, which exhibit structural characteristics closely resembling human teeth, were used. The samples were subjected to an in-office bleaching procedure using a gel containing 35% hydrogen peroxide. Color measurements were performed using a digital spectrophotometer both before and after bleaching. Subsequently, the following pigments commonly used in cosmetic and medical products were applied to the bleached enamel surfaces: blue covarine, white food dye, titanium dioxide, indigo extract, and nano-hydroxyapatite (n-HAP). Granulated coffee was used as the positive control group, and distilled water served as the negative control. Color changes were analyzed using a spectrophotometer.

Results: The groups in which blue covarine and titanium dioxide were applied exhibited significantly lighter color values after bleaching compared to the other groups (P< 0.05). While a slight increase in whiteness was observed in the na-HAP group following bleaching, a marked darkening in color occurred in the coffee group.

Clinical significance: Light-colored pigments, like blue covarine and titanium dioxide, support color stability after tooth bleaching and may enhance the effectiveness of the bleaching treatment by ensuring longer-lasting esthetic results.

Purpose: To evaluate the effects of different preparation designs and ceramic materials on the marginal adaptation and failure load of laminate veneer restorations (LVRs) on premolars.

Methods: Premolar LVRs (0.4 mm thickness) were fabricated using featheredge (F) and butt-joint (B) preparations and four ceramics; Cerec Tessera (CT), Vita Enamic (VE), IPS e.max CAD (EmC), and IPS e.max Press (EmP) (n= 80). Marginal gap (MG) was measured by silicone replica technique. After cementation on epoxy resin dies and 5,000 thermal-cycles, failure load (FL) was tested at the buccal cusp (0.5 mm/minute). Data were analyzed with a two-way ANOVA, Tukey, t-test, (P< 0.05), and fracture types were classified.

Results: Preparation design and ceramic material had statistically significant effects on MG and FL (P< 0.001). B design showed significantly better MG and FL values than F design (P< 0.05). VE exhibited the lowest MG for both preparations, whereas EmP showed the highest MG for B, and EmP and CT for F (P< 0.05). CT showed significantly higher FL than EmP for both preparations (P< 0.05). All failures were catastrophic.

Clinical significance: The findings of this study provide clinical guidance for the selection of preparation design and ceramic material on premolar LVRs for smile design treatments. The results suggest that butt-joint preparation offers better mechanical strength and marginal adaptation, while CAD-CAM ceramics outperform pressed ceramics.

Purpose: To comparatively evaluate the dentin bond strength and color stability of expired and non-expired resin composites (RC).

Methods: 48 caries-free teeth were randomly divided into four groups. The specimens were ground to expose the dentin, and an adhesive (GC Premio Bond) was applied and light-cured. RC (GC G-ænial) in shade A2 was applied to each group (according to its expiration date) using a transparent mold (4 mm x 2 mm) and polymerized. Group 1: expired for 2 years; Group 2: expired for 1 year; Group 3: 1 year remaining until expiration; Group 4: 2 years remaining until expiration. The specimens were immersed in distilled water for 24 hours and then placed in a tea solution, with color measurements taken using a spectrophotometer (EasyShade V) on the 1st, 7th, and 28th days. (CIEDE 2000 formula: L* = 94.48, a* = 0.16, and b* = -0.21). After the color measurements, the specimens underwent a shear bond strength test applied to the bonding interface between the tooth and the composite using a universal testing machine and the values were recorded.

Results: The E1 measurements exhibited the lowest mean color change (5.88 ± 1.02), whereas the E3 measurements had the highest mean color change value (10.13 ± 3.35). The lowest bond strength was observed in Group 1 (97.25 ± 20.33), while the highest value was found in Group 4 (149.45 ± 32.75). The differences between Group 1 and Groups 3 and 4 were statistically significant.

Clinical significance: In clinical practice, adherence to proper storage conditions and expiration dates is essential to ensure the success and quality of resin composite materials, which are frequently used in routine dentistry. Within the limitations of this study, the color stability and bond strength of resin composites decreased after expiration dates. Therefore, to achieve optimal clinical results, it is crucial to ensure that restorations are performed using non-expired resin composites.