American journal of dentistry最新文献

Purpose: To evaluate flow profile and non-Newtonian behavior of 10 different silicone lining materials.

Methods: Ten commercially available silicone lining materials were selected for evaluation. The flow profile and non-Newtonian behavior of each material was measured using a shark fin testing method. Fin height and resultant base thickness were measured with a digital caliper and compared with one-way ANOVA and Student-Newman-Keuls post hoc test and fin base by Kruskal-Wallis one-way ANOVA on ranks with Dunn post hoc test with significance at P< 0.05 for both.

Results: Shark fin heights ranged from 9.62 ± 0.86 mm [Reline II (Soft)] to 25.54 ± 0.43 mm [Sofreliner (Medium)]. Shark fin bases ranged from 2.57 ± 0.51 mm [Sofreliner (Medium)] to 10.31 ± 0.57 mm [Reline II (Soft)]. Statistically significant differences were found between certain samples' shark fin heights as well as resultant bases (P< 0.05) indicating different rheological properties.

Clinical significance: Silicone liner materials differ significantly with respect to flow profile and non-Newtonian behavior. While a high flow profile (low viscosity) of an elastomeric impression material improves accuracy, it may be a detriment to a denture lining material that must achieve a critical minimum thickness to provide resilience. Likewise, a low flow profile (high viscosity) material may also pose a disadvantage, requiring excessive compression and possible tissue distortion to achieve the same critical thickness. The results of this study should be considered when selecting the appropriate material for clinical application. Additional studies are indicated to further quantify rheological properties as well as correlate them to physical properties after the complete cure of the material.

Purpose: To evaluate and compare the laboratory compressive strength (CS), flexural strength (FS), and diametral tensile strength (DTS) of Cention Forte and three bulk fill restorative materials.

Methods: A total of 168 specimens were prepared following the manufacturers' instructions and standards for testing CS, FS, and DTS. Mechanical properties of Cention Forte (LC-Cent) were compared to three commercial bulk-fill materials for posterior restorations: Fuji IX Extra (Fuji), Tetric PowerFill (TPF), and Equia Forte HT (Equia). The tests were performed 24 hours after storage in distilled water on a universal testing machine at a crosshead speed of 0.75 mm/minute. Strength values (MPa) were calculated and statistically analyzed by one-way ANOVA and Tukey's post hoc test (P< 0.05).

Results: Analysis showed significant differences between tested materials for CS, FS, and DTS (P= 0.0001). LC-Cent showed the highest mean value for FS (112.8 MPa) with a significant difference compared to Fuji and Equia. DTS (49.2 MPa) of LC-Cent was significantly higher than all tested materials. TPF showed the highest mean value (180 MPa) for CS but without significant difference compared to LC-Cent.

Clinical significance: Ion-releasing material Cention Forte, according to obtained results, may serve as a viable alternative for posterior restorations compared to conventional bulk-fill restorative materials.

Purpose: To assess and compare the effects of sonic and ultrasonic instrumentation on shear bond strength (SBS) and investigate the influence of adhesive system application modes (etch&rinse/self-etch) on SBS.

Methods: In this experimental study, 45 extracted sound human molars were selected. Mesial and distal surfaces of the teeth were abraded until 90 smooth enamel surfaces were obtained. Specimens were divided into two groups, with half (N= 45) conditioned in etch&rinse mode and the remaining (N= 45) in self-etch mode using Tetric N Bond Universal. Composite resin discs were produced on these surfaces by filling Teflon molds. All specimens were aged via thermocycling. Each group was further divided into three more groups (n= 15) according to the type of periodontal instrumentation (ultrasonic, sonic or none). SBS values were recorded and analyzed using two-way ANOVA. Fracture sites were examined under a stereomicroscope.

Results: The type of periodontal instrumentation had no significant effect on SBS values, whether sonic, ultrasonic or their absence (P= 0.945). The type of adhesive system mode had a significant influence on the shear bond strength values. Etch&rinse groups had significantly higher shear bond strength values than self-etch groups (P< 0.001).

Clinical significance: This study reassures practitioners that sonic and ultrasonic instruments are safe for enamel bonding and highlights the importance of selecting adhesive techniques for optimal restorative outcomes.

Purpose: To evaluate and compare changes on the surface roughness of conventional and colored compomers used in pediatric dentistry caused by beverages frequently consumed by children.

Methods: 176 conventional and colored compomer discs were prepared. The discs were divided into four equal subgroups and incubated in different beverages: distilled water, milk, fruit juice, and cola. The surface roughness of the samples was measured and recorded on Days 1, 7, 14, 21, and 28. The data obtained were statistically analyzed.

Results: In distilled water and milk, the surface roughness of the conventional compomer was higher than the colored compomer after Day 7 (P< 0.05). In fruit juice and cola, the surface roughness of conventional and colored compomers was similar at all timepoints (P< 0.05). There was a significant difference between discs incubated in distilled water and milk, on Days 21 and 28 (P< 0.05). The colored compomer showed the highest roughness in cola on Day 1, whereas the conventional compomer showed the highest roughness in milk on Day 21.

Clinical significance: Cola caused the highest surface roughness on the surface of colored compomers, whereas milk caused the highest surface roughness on conventional compomers.

Purpose: To examine the effects of coffee staining and bleaching applications on the optical properties of CAD-CAM blocks, and to provide a three-dimensional visualization of surface changes with atomic force microscope (AFM).

Methods: 80 samples were prepared from four different CAD-CAM blocks: [Cerec (CR), Shofu (SH), Cerasmart (CRS), Lava Ultimate (LU)], and a microhybrid composite resin [Filtek Z250 (Z250)]. After staining, the samples were divided into two subgroups according to bleaching methods: 16% carbamide peroxide (HB), and 40% hydrogen peroxide (OB). Color measurements were performed at baseline (t₀), after staining (t₁), and after bleaching (t₂) to obtain translucency parameters (TP₀₀), color change (ΔE₀₀), and whiteness index (WID) values. Surface roughness analysis (Ra) was performed with AFM after coffee staining and bleaching procedures (at t₁ and t₂). Data were analyzed with Generalized Linear Model, and Bonferroni correction (P< 0.05).

Results: TP₀₀ values increased only in the CRS group after the bleaching application, and the effect of method was again observed only in CRS. While bleaching increased WID values of all groups except CRS, no difference was found between bleaching methods. Regardless of evaluation time, the roughest group is Z250, and the only difference between bleaching methods was observed in the CR group. In conclusion, the effects of staining and bleaching applications on the optical and surface properties of CAD-CAM blocks are material-dependent.

Clinical significance: Effective bleaching of discolored CAD-CAM materials was achieved regardless of the bleaching method used, and without any significant adverse effect on the surface properties of the materials.

Purpose: To evaluate the wear of different materials used for pit and fissure sealing applied with non-invasive and invasive preparation techniques.

Methods: A total of 170 molar teeth were divided into two main preparation groups (non-invasive and invasive), each consisting of eight subgroups after a control group was separated for wear standardization. Eight subgroups included: nano-filled flowable composite (Filtek Ultimate Flow), nanohybrid flowable composite (GrandioSo Flow), micro-hybrid flowable composite (Majesty Flow), resin-based unfilled fissure sealant (ClinPro Sealant), resin-based filled fissure sealant (Fissurit FX), resin-based highly filled fissure sealant (GrandioSeal), giomer-based fissure sealant (BeautiSealant), and glass-ionomer-based fissure sealant (Fuji Triage) (n= 10). The materials were applied according to the manufacturers' instructions. The initial data were obtained for wear analysis. The specimens were subjected to 2-year thermocycling and brushing simulations. Final data were obtained, and the wear characteristics were evaluated digitally. Data were statistically analyzed (P< 0.05).

Results: There were no significant differences in wear between the non-invasive and invasive application groups (P< 0.05). In comparison of the materials, flowable composites presented the lowest wear (0.15 P± 0.13), and glass-ionomer-based fissure sealant presented the highest wear (0.66 P± 0.32).

Clinical significance: The present study reported that the invasive preparation technique, which slightly abrades the enamel surfaces, did not adversely affect the wear of the sealant materials. Although the application of flowable composites as fissure sealants with a bonding agent is time-consuming and costly, it yielded better results in terms of wear.

Purpose: To evaluate the arresting effect of micro-invasive (resin infiltration) and non-invasive (fluoride varnish) treatment options on non-cavitated proximal lesions in individuals with moderate to high risk of caries. In addition, the study evaluated the effect of repeated dental examinations and oral hygiene motivation on daily flossing, brushing frequency, dietary habits, and gingival status.

Methods: The study was a randomized, controlled, prospective, and parallel-designed clinical trial. 60 adults were enrolled and randomly allocated in a 1:1 ratio to the treatment groups. Cariogram was used to assess the caries risk. The advising instruction for daily habits and oral hygiene by individual risk illustration was given to all participants. Two experienced examiners visually evaluated the severity and activity of the lesions by using the International Caries Detection and Assessment System and Nyvad Activity Assessment respectively. Radiographic scoring of the lesions was performed on bite-wing radiographs by the same examiners. The gingival index was used to check the gingival status of the patients at the initial and control sessions. After examination, resin infiltration (Icon) was applied to 30 subjects, while the other 30 received fluoride varnish (Clinpro White Varnish). The follow-up time was 18 months with 6-month intervals.

Results: According to the Pearson Chi-Square test, there was no difference in the arresting effect of resin infiltration and fluoride varnish (P= 0.491). Both treatment groups exhibited a notable arresting effect on non-cavitated lesions, achieving a success rate of 98% (55 out of 56) during the 18-month evaluation period. However, one lesion of a subject who received resin infiltration was observed to progress from an E2 score to cavitation. Furthermore, at the end of 18 months, the subjects' motivation for oral hygiene had increased, and gingival index score decreased from 2 to 1 in 15% of the subjects.

Clinical significance: Both resin infiltration and fluoride varnish yielded satisfactory results in the treatment of non-cavitated proximal lesions in individuals with moderate to high risk of caries. Repeated motivational instructions were beneficial for patients in maintaining their daily oral hygiene habits and gingival health.

Purpose: To evaluate and summarize the available scientific evidence regarding antibiotic prescription protocols in periodontal and dental implant procedures.

Methods: A bibliographic search was conducted in PubMed, ScienceDirect, Scielo, Cochrane Library, EBSCOhost and Google Scholar up to February 2023. Manual and electronic searches were conducted, including publications in English. Medical Subject Headings (MeSH), free text terms and Boolean operators were used.

Results: Antibiotic prescription protocols have been restricted due to antimicrobial resistance. While for certain clinical circumstances there are guidelines with clear and unanimous criteria for appropriate antibiotic use, for other conditions evidence showed an insufficiency of available literature and the persistence of crucial issues where no consensus has been reached.

Clinical significance: This mini-review summarizes the most up-to-date recommendations regarding the prescription of antibiotics in periodontal and dental implant procedures in order to guide evidence-based decision-making.

Purpose: To evaluate the impact of simplified or multi-step polishing techniques on the roughness, color, and susceptibility to staining of different resin composites.

Methods: Discs (Ø6 mm x 2 mm) were obtained from different resin composites [nanofilled (Z350XT), suprananofilled (Estelite Omega), and nanohybrid (Forma)]. The specimens (n= 15) were submitted to a simplified protocol using abrasive discs (Sof-Lex) and spiral discs (Diacomp Plus Twist), or a multi-step protocol using abrasive discs (Sof-Lex), abrasive points (Jiffy), silicon carbide brush and felt disc with diamond pastes (Diamond Polish). The specimens were evaluated initially for roughness (Ra) and color (CIEL*a*b*, CIEDE 2000), after completing the polishing protocol, and after exposure to a coffee solution (pH= 5.01). The data were analyzed according to the variables, using generalized linear models, and the Friedman, Nemenyi, Kruskal-Wallis, Dunn, and Mann-Whitney tests (α= 0.05).

Results: The nanohybrid resin composite showed an increase in Ra following use of both polishing methods (P= 0.038). Both techniques promoted an increase in L* values after polishing; however, the general color changes (ΔEab and ΔE₀₀) were greater after the multi-step polishing (P< 0.05). After immersion in coffee, the multi-step polished groups of the nanohybrid and suprananofilled resin composite showed higher L* values than the simplified polishing groups (P= 0.023), and the nanofilled resin composite showed higher ΔEab and ΔE₀₀ values than the other resin composites, regardless of the polishing technique (P< 0.05).

Clinical significance: The choice of the resin composite had a greater effect on roughness, color stability and susceptibility to staining than the polishing technique. However, luminosity after coffee staining was higher with the multi-step polishing technique.

Purpose: To assess the effects of adhesive resin cement, obturation material and dentin location on the retention of glass fiber-reinforced resin composite (FRRC) posts.

Methods: 60 root canals in single rooted teeth were obturated with three different protocols (n= 20), including no obturation material (Control), GuttaFlow and Gutta-percha. Spaces were prepared for glass (FRCR) posts. Subgroups of the roots (n=10) were allocated for receiving posts luted with RelyX Unicem or Calibra resin cements. The specimens were mounted in plastic molds using epoxy resin. They were sectioned transversely to obtain three 1 mm-thick coronal, middle and apical slabs. Post retention was measured using a universal testing machine. The push-out test was performed at a crosshead speed of 0.5 mm/minute until post dislodgement occurred. Dislodged posts were examined microscopically to evaluate the mode of failure. Data were analyzed using univariate tests to reveal the effects of dependent variables and their interactions on post retention. Tukey test was used to determine significant differences for post retention in obturation material and dentin location groups. P-values ≤ 0.05 were considered significant.

Results: The adhesive resin cement, obturation material, dentin location and cement obturation materials interaction affected post retention. The mean bond strength was higher for posts cemented with RelyX Unicem than for those cemented with Calibra resin cements. Post retention in coronal locations was significantly superior to middle or apical locations. The failure mode was primarily mixed.

Clinical significance: When using RelyX Unicem cement for luting glass fiber-reinforced root canal posts, complete removal of all obturation materials from the post space significantly improves the retention. Although Calibra cement is less technique sensitive than RelyX Unicem resin cement, it produces notably lower retention of fiber-reinforced glass root canal posts.