American journal of dentistry最新文献

Purpose: To assess the impact of formulation chemistry on gingivitis effects of two experimental 0.454% stannous fluoride (SnF2) dentifrices with low tin bioavailability versus positive and negative controls.

Methods: Adults with gingivitis were enrolled in this double-blind, parallel group, randomized clinical trial. Gingivitis was assessed with the Löe-Silness Gingivitis Index (LSGI) at baseline, 1 month, and 3 months. The four treatments were: experimental dentifrice A (0.454% SnF2, pH 4.7, soluble tin = 592 ppm), experimental dentifrice B (0.454% SnF2, pH 5.8, soluble tin = 102 ppm), positive control (0.454% SnF2 commercial dentifrice, soluble tin = 2,037 ppm), and negative control (0.76% sodium monofluorophosphate, soluble tin = 0 ppm). Participants brushed for 1 minute twice daily with their assigned dentifrice and a standard manual toothbrush. The primary clinical endpoint was number of gingival bleeding sites. In vitro analyses characterized tin uptake into biofilm and bacterial glycolysis.

Results: Of 120 participants randomized to treatment, 115 completed the study. Baseline mean number of bleeding sites (SD) was 35.11 (17.479). At 1 and 3 months, respectively, the mean was 19.52 and 16.64 for the positive control, 26.91 and 21.71 for Experimental dentifrice A, 31.01 and 27.59 for Experimental dentifrice B, and 33.20 and 29.59 for the negative control. At 1 and 3 months, the positive control showed significantly fewer bleeding sites versus all treatments (P≤ 0.04) and Experimental dentifrice A had significantly less bleeding versus the negative control (P≤ 0.041). Experimental dentifrice B was not significantly different from the negative control (P≥ 0.438) at either timepoint. Tin biofilm uptake and in vitro PGRM exhibited a similar trend.

Clinical significance: SnF2 dentifrice formulation chemistry influences the level of antigingivitis efficacy, which was also reflected in tin bioavailability, tin uptake into biofilm, and bacterial glycolysis inhibition.

Purpose: To evaluate the laboratory effects of different whitening toothpastes on human anterior teeth that had undergone in-office bleaching with a 40% hydrogen peroxide (HP) agent.

Methods: Fifty caries-free human anterior teeth extracted for periodontal or orthodontic reasons were randomly assigned to five groups (n=10): Group 1 (Control) : Bleached but no toothpaste applied; Group 2: Ipana Kalsident Classic Taste toothpaste; Group 3: Colgate Optic White Expert toothpaste; Group 4: Signal White Now Gold toothpaste; Group 5: Opalescence Whitening toothpaste. Baseline and post-bleaching color measurements were performed using a digital spectrophotometer. Following bleaching with 40% HP (Opalescence Boost 40% PF), the control group was brushed with distilled water, while the experimental groups were brushed with the respective toothpastes twice daily for 30 days using a rechargeable toothbrush. Final color measurements were recorded, and color changes (ΔE₀₀) were calculated using the CIE2000 formula. Data were analyzed using ANOVA and Tukey tests (P= 0.05).

Results: The use of whitening toothpastes after bleaching significantly enhanced tooth color. Opalescence Whitening exhibited the greatest effect, followed by Colgate Optic White Expert. Signal White Now Gold demonstrated significantly higher efficacy than Ipana Kalsident Classic Taste. However, no significant difference was observed between the control group and Ipana.

Clinical significance: This study demonstrated that whitening toothpastes play a beneficial role in maintaining and enhancing tooth color following in-office bleaching. Clinically, the use of an appropriate whitening toothpaste is recommended to prolong and optimize the results of bleaching procedures.

Purpose: To describe the existing literature on the emerging role of the oral microbiota in shaping both oral and systemic health.

Methods: A narrative review was performed. PubMed, EMBASE and Scopus databases were searched for relevant articles published in the English language.

Results: The oral microbiota plays a crucial role in both oral and systemic health, yet its composition and functions have been underexplored compared to the gut microbiota. The oral cavity harbors a diverse range of microorganisms, including bacteria, fungi, viruses, archaea, and protozoa, which interact within biofilms to influence oral health. The microbiome is influenced by various factors such as diet, oral hygiene, smoking, alcohol consumption, socioeconomic status, pregnancy, and genetics. Dysbiosis in the oral microbiota has been linked to a range of oral diseases, including dental caries, periodontal diseases, oral candidiasis, and even oral cancer. Additionally, oral bacteria can impact systemic health, with emerging associations to cardiovascular disease, respiratory conditions, and various cancers. Effective management of oral dysbiosis involves strategies such as mouthwashes, dietary modifications, and supplementation with probiotics and prebiotics, which can modulate the microbiota, enhance immune responses, and reduce pathogenic growth.

Clinical significance: Oral microbiota dysbiosis, beyond its role in mediating oral diseases, is emerging as a driver of a range of systemic health conditions, including cardiovascular disease, respiratory conditions, and various cancers. A holistic approach combining regular oral hygiene, balanced nutrition, and microbiome-targeted interventions is essential for maintaining oral health and potentially preventing associated systemic diseases.

Purpose: To evaluate the laboratory effects of various energy and sports drinks on the surface microhardness and roughness of dentin.

Methods: 60 extracted, sound bovine incisors were selected. After embedding the crown segments in acrylic resin blocks, the buccal surfaces were ground to expose a flat dentin surface. The dentin specimens were randomly divided into six groups (n=10): (DW) Distilled water (negative control), (M) Monster, (RB) Red Bull, (IS) Isostar, (PR) Powerade, and (CC) Coca-Cola (positive control). Following the initial microhardness and roughness measurements, the specimens were immersed in the beverages, with pH and titratable acidity (TA) values measured, three times a day for 20 minutes. After 7 days, final measurements were recorded. A single specimen from each group was examined under a scanning electron microscope. Data were analyzed using one-way ANOVA, Bonferroni, Tukey, and Games-Howell tests (P< 0.05).

Results: All groups showed a significant reduction in microhardness, except for the DW group (P< 0.05). While there were no statistically significant differences between the RB and M groups (P> 0.05), significant changes in microhardness were observed between RB and the other tested groups (P< 0.05). An increase in surface roughness was observed in all tested groups except DW (P< 0.05). All the tested sports and energy drinks caused a reduction in surface microhardness and an increase in surface roughness. The consumption of these beverages may increase the risk of dental erosion.

Clinical significance: The excessive consumption of sports and energy drinks might have harmful effects on dentin tissue. Individuals should be advised to limit their intake of such beverages.

Purpose: To evaluate the effect of placing short fiber reinforced composites (SFRC) and posterior composites with different techniques on the fracture resistance of teeth: traditional incremental technique (IT), or snowplow (SP).

Methods: Short fiber reinforced resin composite was applied using the incremental technique in SFRC-IT groups and the snowplow technique in SFRC-SP group. Teeth without any cavity formed the positive control group. The samples were exposed to various temperature changes with the application of thermal cycles and were then prepared for the fracture resistance test. Force values were recorded at the point of fracture. Data were analyzed using ANOVA with Tukey HSD (P =  0.05).

Results: Significant differences in fracture resistance were determined between the groups. The Tukey HSD test showed that the fracture resistance of the SFRC-SP group was statistically significantly lower than that of the SFRC-IT it and positive control groups (P= 0.003).

Clinical significance: Application of short fiber reinforced composite with the snowplow technique resulted in lower mechanical values, whereas application with the incremental technique provided high mechanical characteristics like those of the control group.

Purpose: To evaluate the influence of thickness on the color, translucency, and fluorescence of bioactive restorative materials.

Methods: Cylindrical specimens were prepared in 1 and 2 mm-thicknesses with bioactive materials (n= 12): bioactive composite (Activa BioACTIVE Restorative - ABR); alkasite (Cention N - CNN); glass-hybrid material (EQUIA Forte Fil - EFF); and bovine enamel/dentin - ED, as control. The color (CIELAB coordinates) of the specimens was measured using a spectrophotometer against a white and black background, and the translucency parameter (TP₀₀) was calculated. The fluorescence was assessed using a spectrofluorophotometer. Data were analyzed with two-way ANOVA and Tukey's test (α= 0.05).

Results: ABR and CNN exhibited reduced L*, a* and b* values over a white background at 2 mm compared with 1 mm. No differences in CIELAB coordinates were detected between the thicknesses when materials were measured against the black background. For both thicknesses, ABR exhibited the highest TP₀₀ values, and EFF the lowest. At 2 mm, CNN and ED presented similar translucency. ED showed the highest fluorescence values, followed by ABR, CNN, and EFF. The thickness influenced CIELAB parameters of the bioactive materials tested only when a white background was used. The bioactive composite exhibited a reduction in both L* and b* values as the thickness increased. In contrast, alkasite reduced only in L*, while glass-hybrid decreased in b*. As the thicknesses increased, the translucency parameter decreased for the bioactive restorative materials. The thicknesses had no effect on fluorescence of the materials.

Clinical significance: Variations in the thickness of bioactive materials affect CIELAB coordinates only when applied against a white background. Therefore, dentists should consider the intraoral background when using these materials. While thickness does not affect fluorescence, greater thickness reduces translucency.

Purpose: To compare the laboratory push-out forces on titanium cylinders attached to immediate provisional heat-polymerized acrylic resins using different relining material types in varying thicknesses, and to investigate the fracture types.

Methods: Heat-polymerized acrylic discs (Futura Basic Hot) (n= 105) were manufactured with artificial first molar teeth centered in each specimen (diameter: 24 mm, height:10 mm). Discs were drilled to create 6 mm, 8 mm and 10 mm diameter holes, corresponding to connection thicknesses of 1 mm, 2 mm, and 3 mm, respectively, around the 4 mm diameter titanium cylinders (n= 35/group). Each group was divided into five relining resin subgroups: Futura Basic Hot, Ufi Gel Hard, Qu-resin, Quick Up, and Pattern resin (n= 7/subgroup). Titanium cylinders were fixed into the holes, and the gaps were filled with relining resins. After 5,000 thermal cycles, a push-out test was performed (1 mm/minute). Data were analyzed with two-way ANOVA and Tukey post hoc tests (P= 0.05) and failure types were classified.

Results: Resin types, connection thicknesses, and their interaction significantly affected the push-out forces (P< 0.05). Futura Basic Hot showed the lowest push-out forces (171 ± 39 N, 317 ± 131 N, and 144 ± 78 N, for 1 mm, 2 mm, and 3 mm connection thickness groups, respectively) (P< 0.05). Qu-resin and Pattern resin had the highest push-out force for 1 mm (1,235 ± 375 N and 1,576 ± 272 N, respectively) and 3 mm (1,333 ± 127 N and 1,406 ± 82 N, respectively) connection thicknesses. Qu-resin, Ufi Gel Hard, Pattern resin, and Quick Up (2,065 ± 342 N, 1,835 ± 630 N, and 1,626 ± 106 N, 1,501 ± 312 N, respectively) all performed well for 2 mm (Plt; 0.05). 2 mm connection thickness resulted in the highest push-out forces, except for Pattern resin. Qu-resin and Pattern resin are suitable for all connection thicknesses, while Ufi Gel Hard and Quick-Up perform optimally with connection thickness of 2 mm. Futura Basic Hot results in weaker push-out forces for implant-supported immediate provisional hybrid prostheses (IPHPs) fixation. 2 mm connection thickness is generally recommended for improved push-out force.

Clinical significance: The choice of relining resin material and connection thickness significantly influence the push-out force on titanium cylinders attached to IPHPs. Selecting appropriate resin material types and thicknesses can enhance the long-term stability and clinical performance of IPHPs, reducing the risk of fractures during implant osseointegration period.

Purpose: To compare the microhardness, microroughness, and topography of the enamel surface via Vickers microhardness, atomic force microscopy (AFM), and profilometry values before and after the use of 32% and 37% acetic acid and 32% phosphoric acid.

Methods: Four groups were established: Group 1: control group; Group 2: phosphoric acid gel (Scotchbond Universal Etchant) at 32%; Group 3: 32% acetic acid gel; and Group 4: 37% acetic acid gel. The microhardness was determined with a Vickers indenter (VHN). The topography and microroughness of the enamel were analyzed using 3D images obtained via AFM in tapping mode. Microroughness was determined using a contact profilometer. An ANOVA and paired t-test was used to compare the average VHN and microroughness both before and after the etching of the enamel surface.

Results: Statistically significant differences were found for average microhardness after the conditioning of the enamel surface of the four groups (P< 0.001). The roughness obtained via AFM revealed differences among the four groups after the use of the three different acid gels. The profilometry assay showed significant post-conditioning differences among all groups. Conditioning with 32% acetic acid partially modified the characteristics of the enamel surface to a greater extent than conditioning with 37% phosphoric acid; furthermore, the use of acetic acid generated microretentions that could be effective for adhesion.

Clinical significance: Acetic acid, an organic biodegradable acid less corrosive than phosphoric acid, can be used to modify the characteristics of the enamel surface, such as microhardness, topography, and microroughness.

Purpose: To investigate the surface roughness (Ra; µm) of three different interim resin materials, which were subjected to chewing simulation.

Methods: Three interim resin materials were evaluated: (1) LCD type (liquid crystal displays) 3D printed (LCD, n= 10); (2) conventional autopolymerizing bis-acrylic (CO, n= 10); (3) DLP type (digital light processing) 3D printed (DLP, n= 10) interim resin materials. The specimens were subjected to 30,000 cycles of chewing simulation. The surface roughness of the materials was compared and scanning electron microscope (SEM) images representing each group were obtained. The Kruskal-Wallis and Mann-Whitney U test were carried out for comparison of the groups. Paired samples t test was used to compare the Ra values of each group separately before and after chewing simulation (α= 0.05).

Results: The mean ± standard deviation values of baseline surface roughness values were 1.252 ± 0.426 for LCD printed resin, 0.715 ± 1.321 for conventional resin, 0.525 ± 0.963 for DLP printed resin. LCD group had the highest Ra 0 values. No statistically significant difference was observed between the CO and DLP group. After 30,000 cycles of simulated chewing, the mean surface roughness values for LCD, CO and DLP groups were 0.992 ± 0.160, 0.524 ± 0.288 and 0.542 ± 0.658, respectively. After chewing simulation, the difference among the Ra1 values of groups were statistically significant (P= 0.014). LCD group had the highest Ra1 values. No statistically significant difference was observed between the CO and DLP group. The difference of Ra values of all interim materials after chewing simulation compared to baseline were not statistically significant.

Clinical significance: Since the results showed that the Ra values in this study were above the plaque accumulation threshold Ra of 0.20 µm and SEM images were consistent with the Ra measurements, care should be taken to adequately polymerize and polish the restoration surface, especially when it is being used for an extended period of time.

Purpose: This prospective clinical study evaluated the tooth color (ΔΕ*ab and ΔΕ₀₀) and whiteness (ΔWID) changes, as well as tooth sensitivity (TS) induced after performing in-office tooth bleaching with or without light-activation of the bleaching gel using Er,Cr:YSGG laser irradiation.

Methods: 20 subjects were enrolled for the study. The bleaching session was conducted with two 20-minute sessions of a 40% hydrogen peroxide bleaching agent assisted by Er,Cr:YSGG laser (2,780 nm) at the left hemiarch and without laser activation on the right hemiarch. ΔΕ*ab, ΔΕ₀₀ and ΔWID were evaluated in central incisors and canines using a clinical spectrophotometer immediately, 7 days and 30 days after the bleaching procedure. TS was evaluated during the bleaching treatments in both hemiarches of the patients using a visual analogue scale.

Results: The results revealed a significant increase in tooth color and whiteness changes following the tooth bleaching in both laser-treated and conventional groups and in all teeth. Tooth color and whiteness changes were observed immediately after the different treatments and were gradually reduced after 7 and 30 days (P< 0.05). Between the conventional and laser-assisted technique, there were statistically significant differences only in canines (P< 0.05) and in lower central incisors (P< 0.05). Mild TS was noticed in 85% of the patients, without differences between the bleaching treatments (P> 0.05).

Clinical significance: Er,Cr:YSGG laser-assisted tooth bleaching treatment may enhance tooth color and whiteness changes but not in all the examined tooth types, without inducing more intense tooth sensitivity compared to the conventional technique.