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Effective management of head and neck cancer (HNC) poses a significant challenge in the field of oncology, due to its intricate pathophysiology and limited treatment options. The most common HNC malignancy is head and neck squamous cell carcinoma (HNSCC). HNSCC treatment includes a combination of surgery, radiation, and chemotherapy. While HNSCC is treatable if diagnosed early, this is often not the case and is considered incurable once in its late stages and metastatic disease has developed. Therapies are also limited once resistant disease has occurred. SP-1-39, a novel colchicine-binding site inhibitor (CBSI), has been recently reported for its potential efficacy in a variety of cancer cell lines including breast, melanoma, pancreatic, and prostate. SP-1-39 also shows abilities to overcome paclitaxel resistance in a paclitaxel-resistant prostate cancer xenograft model. To evaluate the potential of SP-1-39 as a new HNSCC treatment option, herein we systematically performed preclinical studies in HNSCC models using SP-1-39 and demonstrated that, in vitro, SP-1-39 inhibits the proliferation of 2 HNSCC cell lines with low nanomolar IC50 values (1.4 to 2.1 nM), induces HNSCC cell apoptosis in a dose-dependent manner, interferes with migration of HNSCC cells, and leads to HNSCC cell cycle arrest in the G2/M phase. In vivo, SP-1-39 suppresses the primary tumor growth of a Detroit 562 subcutaneous xenograft mouse model in 6- to 8-wk-old, male NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice, with no detectable cytotoxic effects at a low dose of 2.5 mg/kg. This efficacy of SP-1-39 is better when compared with the treatment using a reference chemotherapy drug, paclitaxel at 10 mg/kg. Collectively, these data demonstrate that SP-1-39 is a promising candidate for further development for more efficacious HNSCC treatment. [ABSTRACT FROM AUTHOR]

Background/Aim. The longevity of a dental restoration may be predicted to some degree by its adhesive ability, and this, in turn, can be measured by bond strength testing between restorative materials and tooth structure. The aim of this study was to test an innovative joggle lap shearing jig that integrates the tooth and the entire biomechanical unit into testing, to compare the shear bond strengths of Class I occlusal composite restorations in deep cavity preparations lined with Dycal, Dycal LC, conventional glass ionomer or resin-modified glass ionomer. The mode of failure (adhesive, cohesive, mixed) after debonding was determined by stereomicroscopy. Methods. A total of 150 standardized occlusal cavities were prepared and divided into five groups. The group I cavities (n = 30) were coated with adhesive (ExciTE®F) and filled directly with composite (TetricEvoCeram). The group II and III cavities were lined with Dycal (n = 30) or Dycal LC (n = 30) before placing composite. The groups IV and V specimens were based with Fuji IX (n = 30) or Fuji II LC (n = 30). Shear bond strengths were determined with a universal testing machine and fractured bonding sites were analyzed under stereomicroscope. The mean bond strengths were analyzed using one-way ANOVA test (p < 0.05) and the means between the groups were analyzed with Student’s t-test. Results. The shear bond strength (MPa) of composite restorations in cavities without base (23.91 ± 4.54) was higher than cavities lined with Fuji II LC (17.45 ± 2.74), Fuji IX (8.76 ± 2.57), Dycal LC (13.07 ± 1.84) or Dycal (6.12 ± 1.28). The results using the jogged lap shearing jig were consistent with the literature. Conclusion. The shear bond strength of occlusal composite restorations in deep cavities without liners was greater than cavities lined with Fuji II LC > Fuji IX > Dycal LC > Dycal.

Purpose: To describe a surgical technique for oroantral communication closure and bone regeneration that can meet the needs of an effective, less invasive, and simpler surgery using approaches and biomaterials used in guided bone regeneration (GBR) techniques. The main objective was to close the communication, and the secondary was to achieve bone regeneration., Methods: This retrospective and monocentric case series was conducted using data obtained from the medical records of 28 patients with oroantral communications with bone deficits greater than 3 mm and treated with heterologous cortico-cancellous graft covered with resorbable collagen membranes and heterologous cortical lamina. The primary outcome was closure of the communication, and the secondary outcome was bone augmentation, both tested radiographically and clinically., Results: 28 subjects were treated consecutively for the closure of oroantral communications. The subjects included 16 men and 12 women. The mean age was 57.5 years. Closure was successful in all 28 cases, and radiographic control after 6 months showed bone regeneration in all the cases. This technique was effective in isolating the maxillary sinus from the oral cavity, showing results in terms of seal and healing, and bone regeneration., Clinical Significance: Oroantral communications are frequent in dentistry, requiring special expertise and interventions affecting patient morbidity. The use of a heterologous cortical lamina can allow effective closure of the communication, preventing migration of pathological epithelia while increasing the bone ridge., Competing Interests: The authors declared no conflict of interest with respect to the research, authorship, and/or publication of this article. Dr. Lopez and Dr. Passarelli contributed equally to this work. Dr. Garcia-Godoy and Dr. D'Addona contributed equally to this work., (Copyright©American Journal of Dentistry.)

Purpose: To provide a surgical strategy for small oroantral communication closure and bone regeneration that can meet the needs of an effective, less invasive, and simpler operation by utilizing procedures and biomaterials commonly employed in guided bone regeneration techniques. The primary goal was to close the communication, while the second aim was to achieve bone regeneration., Methods: This retrospective and monocentric case series was conducted using data from the medical records of 12 subjects with oroantral communications and bone deficits greater than 3 mm who were treated with a heterologous cortico-cancellous graft covered in resorbable collagen membranes. The primary outcome was communication closure, whereas the secondary outcome was bone augmentation, which was demonstrated radiographically and clinically., Results: Twelve individuals were treated consecutively for oroantral communication closure. The subjects consisted of eight men and four women. The mean age was 57.5 years. Closure was effective in all 12 subjects, and radiographic examination after 6 months revealed bone reformation in all cases. This procedure effectively isolated the maxillary sinus from the mouth cavity, resulting in seal and healing, as well as bone regeneration., Clinical Significance: Small oroantral communications are frequent in dentistry, often requiring special expertise and interventions that affect patient morbidity. The use of a heterologous cortico-cancellous graft covered with resorbable collagen membranes can allow effective closure of the small communication, preventing migration of pathological epithelia while increasing the bone ridge., Competing Interests: The authors declared no conflict of interest. Dr. Passarelli and Dr. Lopez contributed equally to this work. Dr. Garcia-Godoy and Dr. D'Addona contributed equally to this work., (Copyright©American Journal of Dentistry.)

Purpose: This retrospective observational study aims to evaluate the outcome of a new alveolar ridge preservation (ARP) technique, "Lamina Socket Sealing" (LSS) technique, using a porcine barrier., Methods: 36 subjects with maxillary premolars to be extracted and extensive alveolar wall defects were enrolled and treated. Porcine-derived barriers and mesenchymal membrane were used to seal the extraction socket with alveolar particulate graft. The outcome variables were: radiographical bone changes and clinical outcomes., Results: 36 subjects, 21 females and 15 males were treated. The change in mm (mean + SE) of horizontal ridge width from baseline to 4 months after surgery at the coronal level of the alveolus was +1.25 ± 0.20 mm (P< 0.05), mean level was +0.34 ± 0.1 mm (P< 0.05) and at the apical level was +0.08 ± 0.17 mm (P> 0.05) which was not statistically significant. The buccal and palatal height changes in mm (mean + SE) from baseline to 4 months after surgery were respectively 1.21 ± 0.17 mm for the buccal wall (P< 0.05) and 1.06 ± 0.24 mm for the palatal wall (P< 0.05). The bone volume of all sites allowed for the placement of the planned implants., Clinical Significance: The alveolar ridge preservation technique (Lamina Socket Sealing) using resorbable heterologous cortical lamina with flapless approach allowed not only the preservation of the damaged post-extraction socket, but also minimal ridge augmentation, according to the principles of guided bone regeneration., Competing Interests: The authors declared no conflict of interest with respect to the research, authorship, and/or publication of this article. Dr. Passarelli and Dr. Lopez contributed equally to this study. Dr. Chiapasco and Dr. D'Addona contributed equally to this study., (Copyright©American Journal of Dentistry.)

Purpose: To provide an overview of an innovative surgical approach to guided bone regeneration, the Pack Into Bone (PIB) technique., Methods: Twenty subjects, eight men and 12 women, aged 34 to 68 (mean 51.5) were selected. They were treated with the PiB technique, and upon re-entry surgery, performed 8 months postoperatively, implants were placed, and bone samples were collected by using trephine burs for histological and histomorphometric analysis purposes., Results: Mean ridge width varied between 4.71 (W0) mm and 7.37 mm (W1), measured 8 months postoperatively, with a mean W augmentation of 2.69 mm ± 0.19. Mean height ranged between 8.0 mm (H0) and 11.15 mm (H1), measured 8 months after surgery with a mean augmentation of 3.53 mm ± 0.14 (P< 0.05)., Clinical Significance: Stability and versatility are the pillars of the PIB technique compared to common GBRs. The PIB technique is effective and reduces the difficulty in stabilizing the graft, is more feasible for operators, and decreases morbidity for the subjects., Competing Interests: The authors disclose no conflict of interest concerning the research, authorship, and/or publication of this article. Dr. Lopez and Dr. Passarelli contributed equally to this work. Dr. Garcia-Godoy and Dr. D'Addona contributed equally to this work., (Copyright©American Journal of Dentistry.)

Purpose: This retrospective observational study evaluated the histomorphometric and soft tissue outcome of a new alveolar ridge preservation (ARP) technique, "Lamina Socket Sealing" (LSS) technique, using a porcine barrier., Methods: Patients with maxillary premolars to be extracted and extensive alveolar wall defects were enrolled and treated. Porcine-derived barriers and mesenchymal membrane were used to seal the extraction socket with alveolar particulate graft. An optical scan of the dental arches was performed with an intraoral scanner (Trios 3, 3Shape) at baseline and at a 4-month follow-up. At the time of implant placement, a bone sample was taken at the implant site with a trephine drill (Hager & Meisinger) and subjected to histomorphometric analysis., Results: 36 subjects (21 females and 15 males) were treated. At 4 months, histomorphometric analysis of the bone samples revealed that the percentage of vital bone was 42.87%, 8.75% of residual granules, 30.76% of soft tissue. Linear comparison of the width of the keratinized gingiva showed an increase (mean + SE) of 3.16 ± 0.35 mm. The net volumetric change of soft tissue was (mean + SE) +28.41 ± 19.52 mm³., Clinical Significance: This alveolar ridge preservation technique (Lamina Socket Sealing) using a resorbable heterologous cortical lamina with a flapless approach has proven effective in maintaining adequate soft tissue and grafting of particulate bone and lamina, with a high percentage of viable bone., Competing Interests: The authors declared no conflict of interest for the research, authorship, and/or publication of this article. Dr. Passarelli and Dr. Lopez contributed equally to this work. Dr. Chiapasco and Dr. D'Addona contributed equally to this work, (Copyright©American Journal of Dentistry.)

The rising demand for effective bone regeneration has underscored the limitations of traditional methods like autografts and allografts, including donor site morbidity and insufficient biological signaling. This review examines nanoparticles (NPs) in tissue engineering (TE) to address these challenges, evaluating polymers, metals, ceramics, and composites for their potential to enhance osteogenesis and angiogenesis by mimicking the extracellular matrix (ECM) nanostructure. The methods involved synthesizing and characterizing nanoparticle-based scaffoldsand integrating hydroxyapatite (HAp) with polymers to enhance mechanical properties and osteogenic potential. The results showed that these NPs significantly promote cell growth, differentiation, and bone formation, with carbon-based NPs like graphene and carbon nanotubes showing promise. NPs offer versatile, biocompatible, and customizable scaffolds that enhance drug delivery and support bone repair. Despite promising results, challenges with cytotoxicity, biodistribution, and immune responses remain. Addressing these issues through surface modifications and biocompatible molecules can improve the biocompatibility and efficacy of nanomaterials. Future research should focus on long-term in vivo studies to assess the safety and efficacy of NP-based scaffolds and explore synergistic effects with other bioactive molecules or growth factors. This review underscores the transformative potential of NPs in advancing BTE and calls for further research to optimize these technologies for clinical applications.

Purpose: To evaluate the in vitro antibacterial effect of Softsoap and Efferdent used as solutions to disinfect Lucitone 199 poly(methyl methacrylate) (PMMA) resin used for dentures., Methods: S. mutans and plaque bacteria were grown for 24 hours, and suspended to a concentration of 1x10⁶ cells/ml. Bacterial suspensions (0.2 mL) were added to the decontaminated PMMA discs placed in a 48-well culture plate and incubated for 3 days at 37°C. The discs were rinsed to remove the unbound bacterial cells and then incubated for 60 minutes with 5% and 1% dilutions (triplicates) of each of the detergent solutions (0.3 ml). Discs were rinsed and then MTT reagent (0.2 ml) was added and incubated for 2 hours, then overnight with a solubilizing agent. An aliquot from each well (0.1 ml) was transferred to a 96-well flat bottom plate and absorbance was measured to OD @ 595 nm (MTT) of four samples for each data point. Normalized data was compared and statistically analyzed using a three-way ANOVA with Student-Newman-Keuls on Rank data with P< 0.05 for significance. Additionally, data were double-checked with the Holm-Sidak test., Results: There was no statistically significant difference between testing media for C. albicans and mixed plaque (P= 0.078) or testing duration in time at 24 hours and 21 days (P= 0.07). Statistically significant differences were found between all treatment solutions group combinations (P< 0.001) except for 30% Softsoap versus Efferdent (P= 0.056)., Clinical Significance: There was no statistically significant difference between testing media for C. albicans and mixed plaque (P= 0.078) or testing duration at 24 hours and 21 days (P= 0.07). Statistically significant differences were noted between all treatment solutions group combinations (P< 0.001), However, there was no difference between 30% Softsoap and Efferdent (P= 0.056)., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To investigate the discoloration, line roughness and gloss of conventional and universal shade resin-based composites., Methods: Clearfil AP-X (AP-X) and Estelite Sigma Quick (EQ) samples were prepared. Discoloration, roughness, and gloss were measured on mirror-polished, alkaline-degraded, and repolished surfaces. The superficial layer degraded by alkaline immersion (degraded layer) was ground off from the sample surface. After removing the degraded layer, the surface was polished with aluminum oxide powder (1.0 µm and 0.3 µm), to create a repolished specimen. Scanning electron microscopy observations were made of the specimens., Results: The results were compared with those for Omnichroma (OC) from a previous study. All the materials showed different responses to degradation and repolishing, but repolishing of AP-X, for surface roughness and gloss, was more effective at restoring pre-degradation properties. Repolishing effectively removed discoloration in all materials., Clinical Significance: The materials tested showed different responses to degradation and repolishing, but repolishing of AP-X, for surface roughness and gloss, was more effective at restoring pre-degradation properties. Repolishing effectively removed discoloration in all materials., Competing Interests: The authors declared no conflict of interest. This work was supported by JSPS KAKENHI (Grant-in-Aid for Early-Career Scientists) Grant Number 23K16011., (Copyright©American Journal of Dentistry.)

Purpose: The purpose of this study was to investigate the microleakage of atraumatic glass ionomer restorations with and without silver diammine fluoride (SDF) application. Restorations with SDF are termed silver-modified atraumatic restorations (SMART). Methods: Sixty carious extracted permanent teeth were randomly allocated to two SMART groups and two control groups (n equals 15 per group) for a total of four groups. After selective caries removal, test specimens were treated with 38 percent SDF and polyacrylic acid conditioner was applied and rinsed; teeth were restored with Fuji IX GP® glass ionomer (n equals 15) or with SMART Advantage™ glass ionomer (SAGI; n equals 15). For control groups, specimens were restored with their respective GI material after selective caries removal, both without SDF. Restored teeth were placed in Dulbecco's Phosphate-Buffered Saline solution at 37 degrees Celsius for 24 hours. Teeth were thermocycled between five and 55 degrees Celsius for 1,000 cycles, stained with two percent basic fuchsin, sectioned, and visually inspected for microleakage utilizing stereomicroscopy on a four-point scale. Data were statistically analyzed using Kruskal-Wallis one-way analysis of variance on ranks using Dunn's method (P<0.05). Results: Microleakage between the two SMART restoration groups was insignificant. SAGI alone demonstrated significantly more microleakage than all other groups. There was no statistical significance between the Fuji IX GP® control group and the two SMART restoration groups. Conclusions: This in vitro study indicated that silver diammine fluoride placed before glass ionomer restoration does not increase microleakage. Polyacrylic acid may be used after SDF placement without increasing microleakage.

Purpose: To investigate the effect of painless low-power Er:YAG laser irradiation of conventional and polymer-infiltrated ceramic network (PICN) type CAD-CAM resin-based composites (RBCs) on resin bonding., Methods: An Er:YAG laser system, phosphoric acid etchant, universal adhesive, RBC, and two types of CAD-CAM RBC block were used. Microtensile bond strength, fracture mode, scanning electron microscopy (SEM) observations of bonding interfaces and CAD-CAM surfaces, and surface roughness of ground and pretreated surfaces were investigated. As pretreatment methods, low-power Er:YAG laser irradiation and air-abrasion with alumina particles were used., Results: The effect of low-power Er:YAG laser irradiation of CAD-CAM RBCs on bonding to repair resin varied depending on the type of CAD-CAM RBCs., Clinical Significance: The low-power Er:YAG laser irradiation of the conventional CAD-CAM RBCs was shown to be effective as a surface pretreatment for resin bonding, while the laser irradiation of PICN-type CAD-CAM RBCs was not effective., Competing Interests: The authors declared no conflict of interest. This work was supported by JSPS KAKENHI [Grant-in-Aid for Scientific Research(C)] Grant Number 23K09190., (Copyright©American Journal of Dentistry.)

Objectives: To provide a 3-year follow-up of previously treated patients to assess and compare the periodontal responses and clinical performance of proximal subgingival open sandwich restorations., Materials and Methods: Ninety-five adults participated in the study, with a combined total of 120 compound Class II cavities. These cavities had gingival margins located below the CEJ. Four different restorative materials were used to elevate the dentin/cementum gingival margins of the cavities: resin-modified glass ionomer, glass hybrid, flowable bulk-fill composite, or ion-releasing material, which were then completed with the same overlaying composite. Different periodontal and clinical evaluations, based on the criteria set by the World Dental Federation (FDI) criteria, were performed at different time intervals, including baseline, 6 months, 1, 2, and 3 years., Results: The type of base material did not affect the periodontal evaluations. There were no statistically significant differences between different time intervals or base material groups in any of the evaluated FDI parameters. However, the ion-releasing material scored significantly worse in the radiographic evaluation than any of the other groups., Conclusions: All tested materials are suitable for proximal subgingival open sandwich restorations, as long as the restoration/tooth margin is at least 2-mm away from the bone crest., Clinical Significance: Clinicians can confidently choose any of the tested materials for proximal subgingival open sandwich restorations, as they have shown good outcomes from both periodontal and clinical perspectives., (© 2023 Wiley Periodicals LLC.)

This study aimed to evaluate the periodontal responses of subgingival proximal margins elevated using different restorative materials. A total of 120 proximal cavities with dentin/cementum gingival margins were elevated using one of four materials (resin-modified glass ionomer, glass hybrid, flowable bulk-fill resin composite, or bioactive ionic resin) and completed with the same overlaying resin composite. At 2 weeks (baseline), 6 months, 1 year, and 2 years postrestoration, periodontal parameters and the radiographic distance between the restoration margin and bone crest were evaluated. Appropriate statistical analyses were performed. The values of all periodontal parameters increased with time, although only the increases in Plaque Index and probing depth within each material group were statistically significant. There were no statistically significant differences in any of the periodontal parameters between the different materials within the same evaluation period, nor between different time points or material groups in the radiographic distances. Both glass ionomer-based and resin-based materials were periodontally safe as subgingival open sandwich restorations.

Purpose: To evaluate the influence of group and individual education on shade matching quality using a visual color competency test to match shade tab pairs from two Vita classical A1-D4 shade guides., Methods: 60 dental students, 21-25 years old (39 females, 21 males) participated in the study. All participants passed a color deficiency test before the experiment. The examination was voluntary and approved by the corresponding Ethics Committee. Students were randomly divided into three groups (n=20): one control group, NE (no education) and two experimental groups - GE (group education) and IE (individual education). The study was performed in three phases. In the "before" (B - Phase 1) and "after" (A - Phase 3) phase, all groups had to match 16 pairs of tabs from two Vita classical A1-D4 shade guides, with the shade designations hidden by custom letter markings. All tabs were mixed on a gray surface illuminated by color-correcting light. In Phase 2 (between B and A), GE had only group education, while IE received additional individual education and training. The control group did not participate in Phase 2. Means and standard deviations were calculated, and differences were compared using the one-way ANOVA, ANCOVA test, and Student t-test for dependent samples (α= 0.05)., Results: The NE group matched 10.3 (3.2) and 10.4 (2.9) tab pairs in the before and after phases, respectively. Corresponding results for GE were 11.1 (2.2) and 14.4 (1.9) and 9.5 (3.6) and 15.0 (1.5) for IE, respectively. In Phase 1 (B), no statistically significant difference was recorded among the groups (P= 0.260). The experimental groups achieved a statistically significant improvement compared with the control group in Phase 3 (A) (P< 0.001). Both experimental groups achieved statistically significant improvement within the group after education, GE (P< 0.001) and IE (P< 0.001). Within the limitations of this study, it was concluded that both experimental groups had statistically significant progress in shade matching. The group that received individual education (IE) made statistically significant progress compared with the group that received group education (GE). No statistically significant difference was found in the results of the control group between Phase 1 and Phase 3 of the study., Clinical Significance: Improving the shade matching ability facilitates the work of dentists and dental technicians and enhances the esthetics of dental restorations., Competing Interests: The authors declared no conflict of interest. Dr. Paravina is a consultant for VITA Zahnfabrik., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the effectiveness of whitening toothpaste in restoring tooth color after coffee staining and its potential impact on enamel surfaces compared with regular toothpaste., Methods: Bovine tooth enamel specimens were prepared and stained with coffee solutions before undergoing brushing simulation with different toothpaste slurries (whitening, regular, reference). For precise evaluation, spectrophotometric measurements were taken at intervals to assess color changes using the CIELAB (Commission Internationale de l'Éclairage Lab*) color space. Additionally, profilometric measurements were taken to determine the impact of toothpaste type on the roughness and abraded depth of the enamel surface. To understand the effects of toothpaste and brushing on color change, surface roughness, and abraded depth, while also considering correlations between these factors, the findings were analyzed using mixed-effects models., Results: The whitening toothpaste group demonstrated the highest recovery rate (71%) after 10,000 brushstrokes, followed by the regular toothpaste group (48%) and the reference slurry group (43%). The mixed-effects model analysis revealed that the reference group had a smaller change in lightness (ΔL) than those in the regular toothpaste group. The whitening toothpaste group showed a greater change in lightness on average than those in the regular toothpaste group, with an increase in lightness as the number of brushstrokes increased. According to the roughness and abraded depth data, the whitening toothpaste group was least affected by brushing, while the reference and regular toothpaste groups showed higher levels of roughness and abraded depth at all intervals., Clinical Significance: Gaining a thorough understanding of the effectiveness of whitening toothpaste and its impact on the enamel surface plays a crucial role in refining toothpaste formulations and advancing tooth whitening techniques in dental care., Competing Interests: The authors declare no conflicts of interest related to this research. Ms. Kim and Dr. Yoo contributed equally to this work. This research was supported by Korea Medical Device Development Fund grant funded by the Korea government (the Ministry of Science and ICT, the Ministry of Trade, Industry and Energy, the Ministry of Health & Welfare, the Ministry of Food and Drug Safety) (Project Number: 1711134912, RS-2020-KD000002), and partly supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2021R1l1A2048516)., (Copyright©American Journal of Dentistry.)

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., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Objectives: This study aimed to investigate the elemental analysis and microhardness of a bioactive material (Activa) and marginal tooth structure after storage in different media., Materials and Methods: Fifteen teeth received cervical restorations with occlusal enamel and gingival dentin margins using the tested material bonded with a universal adhesive, 5 of them on the 4 axial surfaces and the other 10 on only the 2 proximal surfaces. The first 5 teeth were sectioned into 4 restorations each, then stored in 4 different media; deionized water, Dulbecco's phosphate buffered saline (DPBS), Tris buffer, and saliva. The storage period for deionized water was 24 hours while it was 3 months for the other media. Each part was analyzed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis for different substrates/distances and the wt% of calcium, phosphorus, silica, and fluoride were calculated. The other 10 teeth were sectioned across the restoration, stored in either Tris buffer or saliva for 24 hours or 3 months, and were evaluated for microhardness of different substrates/areas. Data were analyzed using analysis of variance and Tukey's post hoc test., Results: Enamel and dentin interfaces in the DPBS group exhibited a significant increase in calcium and phosphorus wt%. Both silica and fluoride significantly increased in tooth structure up to a distance of 75 μm in the 3-month-media groups than the immediate group. Storage media did not affect the microhardness values., Conclusions: SEM-EDS analysis suggests an ion movement between Activa and tooth structure through a universal adhesive while stored in DPBS., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2024. The Korean Academy of Conservative Dentistry.)

Purpose: To evaluate the amount of dentin loss following immersion in or toothbrushing with whitening toothpaste (WT) containing hydrogen peroxide (HP) and citric acid (CA). Additionally, the amount of dentin loss after brushing with a WT alone or in combination with a conventional toothpaste was assessed, and the effects of HP and CA solutions on the dentin surface were investigated., Methods: Bovine dentin specimens (n= 350) were randomly assigned to seven solutions of various compositions as toothpaste: The specimens assigned to each solution were then further divided into five treatment groups (n=10 each) : Group A = 1-hour immersion in each solution (ES); Group B = 10,000 brushing in ES; Group C = 1-hour immersion in ES + 10,000 brushing in ES; Group D = 1-hour immersion in ES + 10,000 brushing in reference slurry (RS); Group E = 10,000 brushing in ES + 10,000 brushing in RS. The amount and pattern of dentin loss were determined, and the surfaces were observed using noncontact profilometry., Results: The WT (pH 5.0) caused lower dentin loss than RS after a single brushing cycle; however, the extent of dentin loss after 1 hour of immersion in the WT was significantly greater than that in the RS. Among the specimens treated with WT, a significant difference in dentin loss was observed between Group C and Groups D and E (P< 0.05) but not between Groups D and E. The surfaces exposed to CAS1, CAPB, and WT exhibited U-shaped patterns of dentin loss after brushing or immersion, whereas a wedge-shaped pattern was observed in those that underwent brushing with the RS., Clinical Significance: The effects (dentin abrasion) of a whitening toothpaste containing hydrogen peroxide and citric acid when used in combination with a conventional toothpaste were similar to those seen with the continuous use of a conventional toothpaste alone., Competing Interests: The authors declared no conflict of interest. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2021R1l1A204851611)., (Copyright©American Journal of Dentistry.)

Aerosols produced by dental handpieces represent a permanent risk of disease transmission in the dental environment. The current study evaluated the effects of natural ventilation (open windows) on Streptococcus mutans airborne contamination by dental handpieces in simulated clinical conditions. A dental phantom was placed on a dental chair at a standard university dental clinic operatory. An S. mutans suspension was infused into the phantom's mouth while an operator performed standardized dental procedures using low (contra-angle) and high speed (turbine) dental handpieces or an ultrasonic scaler, with windows open or closed. Selective medium Petri dishes were placed in 18 sites of the operatory environment to evaluate contamination topographically. Sites were clustered as: wall, floor, ceiling, dental chair, and cabinet. Contamination was expressed as log 10 CFU/cm 2 . A linear mixed model analysis was used, nesting the sites within each ventilation and handpiece combination. Open windows significantly reduced contamination. The high-speed handpiece provided the highest contamination, followed by the ultrasonic scaler and the low-speed handpiece. Contamination values were much smaller at the ceiling, and much larger at the chair. Opening windows produced more homogeneous contamination of the operatory compared to closed windows. Natural ventilation during dental procedures decreases contamination and affects its topographical distribution., (© 2023 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)