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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.)

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: 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.)

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.)

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.)

Purpose: To compare the microhardness values and bottom/top hardness ratios of different composites after being cured in 2 or 4 mm increments., Methods: Two bulk fill composites, methacrylate-based and ormocer-based, and one conventional composite were tested. 36 cylindrical discs were prepared (n=12/composite, with six for 2 mm, and six for 4 mm thickness) by pressing each composite into a mold between two glass slides covered by Mylar strips. The top and bottom surfaces of each sample were evaluated using a Buehler hardness tester for Knoop microhardness, with a 50 g static load applied for 10 seconds at three different locations of the central part of each sample. The bottom/top hardness ratio was calculated for each sample. The Knoop microhardness data and bottom/top ratio percentages were analyzed using two-way repeated measures ANOVA and Holm-Sidak post hoc test, with significance at P< 0.05., Results: The tested methacrylate-based bulk fill had the highest overall microhardness among the three tested composites. All three composite types showed a significant difference in microhardness between the top and bottom of the 4 mm discs. The bottom/top ratio percentages differed significantly for both tested bulk fill composites across different thicknesses. Both tested bulk fill materials had a bottom/top ratio of ≥ 80% at the deepest level of a 4 mm increment., Clinical Significance: The type of material significantly affected both the bottom and top microhardness values under the experimental conditions used. While both tested bulk fill composites showed a decline in microhardness at the bottom of the 4 mm depth, they had clinically acceptable microhardness ratios at greater depths., Competing Interests: The authors declared no conflict of interest. Supported by the University of Tennessee Health Science Center College of Dentistry Alumni Endowment Fund and the Tennessee Dental Association Foundation., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate and compare the effects of different scaling and polishing techniques on the surface roughness of four different restorative materials., Methods: 72 specimens were prepared, molded to a size of 8.0 by 2.0 mm, and cured according to the manufacturers' instructions. The specimens were stored at 37°C for 24 hours and then thermocycled for 5,000 cycles (from 55°C to 5°C) to simulate 6 months of clinical use. Surface roughness (Ra/average and Rz/max-overall heights) was calculated using a stylus profilometer by subtracting the simulated treatments of hand scaling, ultrasonic scaling, and air polishing from the baseline measurements. The difference in Ra and Rz data were compared independently for each measurement using a two-way ANOVA on Ranks and the Holm-Sidak test, with α< 0.05 used to determine significance., Results: Irrespective of the scaling or polishing technique employed, flowable bulk fill demonstrated the lowest Ra and Rz values. Hand scaling exhibited the highest roughness and variability among the other techniques, regardless of the materials tested (P< 0.001). Air polishing with glycine resulted in the lowest roughness values across all tested materials, with the exception of the tested bioactive restorative material group., Clinical Significance: Regarding surface roughness, air polishing with glycine may be an effective and safe intervention for periodontal maintenance of subgingival restorations compared to the other tested scaling methods., Competing Interests: The authors declared no conflict of interest. Supported by the University of Tennessee Health Science Center College of Dentistry Alumni Endowment Fund and the Tennessee Dental Association Foundation., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the effects of toothpaste tablets on the gloss and surface roughness of resin-based composite materials and determine the relationship between gloss and roughness., Methods: Rectangular jigs were designed and printed. Wells (2 mm deep x 7 mm diameter) were filled with Filtek Supreme Ultra A2B, light-cured and polished. A small-area glossmeter was used for gloss (GU) measurements and a profilometer for roughness measurements (Ra) at baseline and after challenge with each toothpaste. An automated tooth-brushing machine was set at 120 strokes/minute for a total of 10,000 strokes to evaluate four test groups with 16 specimens in each group. NC: Brushing with distilled water; TABS: Colgate Anywhere Travel Tooth Tabs; CP: Colgate Cavity Protection Toothpaste and AW: Colgate Whitening Advanced Toothpaste. Kruskal-Wallis test was used to test the difference in gloss and surface roughness among the groups and Pearson correlation was used to compare the relationship between gloss and roughness., Results: There was no statistically significant difference in gloss and roughness among the four groups at baseline. At post-brushing, there was a statistically significant difference among the groups (P< 0.001) with increased roughness and decreased gloss for CP and AW when compared to TABS. There was a statistically significant correlation between post-brushing roughness and post-brushing gloss (P< 0.001, rho: -0.815). Thus, the higher the surface roughness the lower the gloss., Clinical Significance: Toothpaste tablets retain better gloss and roughness of resin-based composite materials when compared to conventional toothpastes., Competing Interests: The authors declared no conflict of interest. The study was supported by the Loma Linda University School of Dentistry Student Research Program Fund., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the potential secondary caries reduction of bulk-fill resin composite restorations treated with different fluoride (F)-based agents prior to restoration placement., Methods: 25 upper extracted molars received Class V cavities on both buccal and lingual surfaces with an enamel margin and root surface margin. The teeth were randomly assigned into five groups with five teeth per group (n=10). The treatment groups were: control group, with no treatment; the other groups received treatment using different F-based agents prior to bonding. All teeth were restored using a selective etch bonding technique and bulk fill resin composite. All teeth received 10,000 thermal cycles followed by immersion in demineralizing solution to produce artificial caries-like lesions. Polarized light microscope evaluation was performed on longitudinal sections (30 enamel lesions and 30 root surface lesions per group). Lesion depth and wall lesions for both enamel and root surface adjacent to the restorations were evaluated., Results: Both lesion depths and frequency of wall lesions in the enamel and root surfaces in all treatment groups were significantly reduced compared with the control group. Among the different F-based agents, no significant difference was seen on the enamel or root surface lesion depth, showing a similar presence of enamel and root cavosurface wall lesions., Clinical Significance: F-based agent treatment of adjacent enamel and root surfaces prior to placement of restorative materials provided resistance to the development of secondary caries during an in vitro caries model., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To compare the amount of abrasion of four whitening toothpastes, two conventional toothpastes, and seven experimental toothpastes with varying concentrations of hydrogen peroxide., Methods: Bovine dentin specimens were treated with the four whitening toothpastes (containing three different concentrations of hydrogen peroxide: 0.75%, 1.50%, and 2.80%), two conventional toothpastes without hydrogen peroxide, seven experimental toothpastes (concentrations of hydrogen peroxide: 0.75%, 1.50%, 3.0%, 4.50%, 6.0%, 7.50%, and 9.0%), and distilled water. After 10,000 strokes of toothbrushing, the amount of abrasion on the dentin surface was measured with a contactless 3D surface profiler (n= 8). The pH of all solutions, the weight percentages of the particles, and the component of particles in the toothpaste were analyzed. The correlations between the dentin abrasion, pH, and weight percentages of the particles in the toothpastes were investigated., Results: The amount of abrasion of the two conventional toothpastes were 1.1-3.6 times higher than those of the four whitening toothpastes. Likewise, the pH of the conventional toothpaste was higher than those of the other whitening toothpastes. No significant differences were found among the four whitening toothpastes. The four whitening toothpastes consisted of a relatively lower weight percentage of particles compared to the two conventional toothpastes. A strong positive correlation was observed between the dentin abrasion and the weight percentages of the particles (r= 0.913; P< 0.05). Furthermore, no significant differences in the amount of abrasion were observed between the specimens treated with seven experimental toothpastes and those treated with distilled water., Clinical Significance: The whitening toothpastes containing less than 9% hydrogen peroxide did not seem to harm the dentin surface significantly. These findings can serve as a reference for consumers, patients, and dental professionals., Competing Interests: The authors declared that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2021R1I1A2048516)., (Copyright©American Journal of Dentistry.)

Purpose: To test the feasibility of nitrogen-doped TiO₂ nanoparticles in the killing of Streptococcus mutans (S. mutans) for short term treatment., Methods: For the study, S. mutans were treated with the combinations of N-TiO₂, visible light, and without/with 0.5% H₂O₂ inclusion. Visible light was irradiated for 3 minutes one time., Results: Methylene blue solution was degraded (bleached) 5-30% by one of N-TiO₂ (or TiO₂) + visible laser (405 or 660 nm) +0.5% H₂O₂ conditions owing to almost linearly producing free radicals through photocatalysis. Antibacterial outcomes treated with N-TiO₂ were slightly better than those by TiO₂ regardless of test condition. Also, killing of S. mutans treated with 405 nm laser was slightly better than those by 660 nm laser., Clinical Significance: S. mutans can be eliminated using N-TiO₂ with clinically acceptable light (wavelength, intensity) and low concentration H₂O₂ condition under short term treatment., Competing Interests: The authors declared no conflict of interest. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MIST) (2019R1F1A1051140)., (Copyright©American Journal of Dentistry.)

Purpose: To test the efficacy of nitrogen doped-TiO₂ (N-TiO₂) nanoparticles (NPs) on teeth whitening under visible light irradiation., Methods: N-TiOV₂ NPs were prepared by the sol-gel method, using TiN as a precursor. Their light absorbance and crystal structures were characterized. Photocatalytic reactions were tested using methylene blue (MB) and extracted teeth. For the extracted teeth, carbomer gel, without or with 3% H₂O₂, and light irradiated, with subsequent evaluation of the color differences., Results: Unlike ordinary TiO₂, N-TiO₂ showed high absorbance after 400 nm. N-TiO₂ prepared with TiN as a precursor showed rutile phase over the TiN structure. For MB solution, N-TiO₂ with 3% H₂O₂ showed the maximum decrease in absorbance after laser irradiation. Observing the effect on teeth, N-TiO₂+3% H₂O₂+405 nm laser treatment achieved approximately 25% higher whitening than that by 15% H₂O₂ during the same treatment time. Higher H₂O₂ concentrations may offer faster results., Clinical Significance: N-TiO₂ nanoparticles (without or with 3% H₂O₂) show better whitening of teeth as compared to 15% H₂O₂, if used with a visible laser for 5 hours. The potential on N-TiO₂ nanoparticles to be used as a tooth whitener needs to be further explored to reduce its application time., Competing Interests: The authors declared no conflict of interest. This study was supported by Dental Research Institute (PNUDH DRI-2022-03), Pusan National University Dental Hospital, Yangsan, S. Korea., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate and compare the effect of pressure during curing on resin composite bond strength to dentin using a self-etch bonding protocol., Methods: 20 human teeth were cut to the mid-coronal dentin and received a standardized smear layer. The prepared teeth were randomly assigned to the following two groups (n= 10/group): (1) without pressure during curing (control) or (2) with pressure during curing. Teeth in the control group received a 4 mm-thick buildup of a nanohybrid resin composite in two separately cured increments, adapted using a composite placement instrument, and bonded with a universal adhesive, while teeth in the treatment group were restored with the same adhesive and resin composite but a plexiglass pressure cylinder was used to apply pressure while each increment was cured. Each group was further divided into two subgroups, one of which was sectioned and subjected to microtensile bond strength (µTBS) testing after 24 hours (immediate samples; n= 5), while the other was subjected to 10,000 thermal cycles (TC; n= 5) prior to sectioning and µTBS testing. The resulting failure patterns were assessed under a stereomicroscope. In addition, one representative specimen from each subgroup was subjected to qualitative microscopic morphological analysis of the internal restoration/dentin interface. Data were analyzed by two-way ANOVA followed by Tukey' post hoc test and values with P< 0.05 were considered to be statistically significant., Results: After TC, the group cured with pressure exhibited significantly higher µTBS values than did the control (P< 0.05), although TC had a detrimental effect on all µTBS values. Microscopic examination revealed that the control specimens had more voids in the resin composite part, relative to specimens that were under pressure during the curing process., Clinical Significance: Pressure application during curing of resin composite may have a positive effect on bond strength to dentin., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To compare the autofluorescence (AF) spectra of resin products with teeth to determine if this type of non-invasive testing is feasible for differentiating resin products from teeth during resin repair., Methods: For the study, 11 methacrylate-based resin products were chosen. A 405 nm laser was used to induce AF, and a spectrophotometer and a qualitative laser-induced fluorescence (QLF) camera were used to obtain AF spectra and images, respectively., Results: Resin products and teeth showed one or two emission peak(s) at 435-465 nm and 475-480 nm, respectively. Other resin constituents produced weak emission peaks beyond the 435-475 nm range. Resin products with high emission intensities produced bright images. When layered, surface resins (0.2 mm-thick) were different from underlying base resins and teeth., Clinical Significance: During resin repair, a restored resin can be readily removed if AF spectroscopy is used alone or in combination with QLF imaging., Competing Interests: The authors declared no conflicts of interest. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (2019R1F1A1058667)., (Copyright©American Journal of Dentistry.)

Purpose: To test the applicability of autofluorescence (AF) spectrum and image in the detection and identification of oral pathogens., Methods: Oral pathogens (Candida albicans, Porphyromonas gingivalis, Streptococcus mutans) and teeth were used. To induce AF, the 405 nm laser was used as a light source, and AF was obtained and observed using a spectrometer, fluorescence camera, and microscope, respectively., Results: The tested oral pathogens had similar spectral distributions, but their peak intensities and peak ratios were different. Their peak positions and spectral patterns were different from those of the tested sound and carious teeth. These differences were also found from the other referenced oral mucosa. Fluorescence image could localize the existence of oral bacteria. Oral pathogens could be imaged by fluorescence, but identification of each pathogen by image was not probable., Clinical Significance: Oral pathogens can be observed and identified from the lesion if autofluorescence spectrum and fluorescence images are combined., Competing Interests: The authors declared no conflict of interest. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (2019R1F1A1058667) and (2019R1F1A1051140)., (Copyright©American Journal of Dentistry.)

Purpose: To investigate and compare the effects of the two widely used regenerative endodontics medicaments: Triple antibiotic paste (ciprofloxacine-metronidazole-clindamycin) and calcium hydroxide on the microhardness and degradation of human root dentin., Methods: Following ethical approval and subject consent to use teeth in this research study, 60 singled-rooted permanent human teeth were randomly divided into six groups:(1) Tri-antibiotic paste with distilled water, or with (2) propylene glycol, (3) calcium hydroxide with distilled water, (4) calcium hydroxide propylene glycol, (5) untreated extracted teeth as negative controls, or (6) teeth instrumented and filled with calcium hydroxide or tri-antibiotic paste as positive controls. The microhardness tests were conducted after 1 and 2 months of exposure to the medicaments using a Vickers microhardness tester. Raman spectroscopy and energy dispersive x-ray spectroscopy were used to evaluate the chemistry and structure of the root dentin., Results: There were differences in the dentin microhardness following treatment with the medicaments or controls (P< 0.05). The time of root dentin exposure to the medicaments was similar (P> 0.05). The root dentin microhardness was lower in the teeth treated with the triple antibiotic paste or calcium hydroxide when combined with propylene glycol. The root dentin collagen in these treated teeth were also significantly degraded when viewed with Raman spectroscopy and energy dispersive x-ray spectroscopy, whereas the inorganic phase (dentin) remained unaltered. Samples exposed to the antimicrobial agents with water as a vehicle exhibited stronger microhardness and less degradation., Clinical Significance: These ex vivo results suggest that the triple antibiotic paste and calcium hydroxide should be used with propylene glycol if a fast diffusion is desired or with water to avoid degrading the collagen and weakening the microhardness of the teeth. Clinical trials are needed of new formulations of medicaments with propylene glycol to disinfect teeth for regenerative endodontic procedures, to help strengthen the teeth to prevent the loss of children's permanent immature teeth by fracture following caries or trauma., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the laboratory long-term effect of various whitening dentifrices on the surface roughness of two brands of resin composite (TPH ST, Filtek Bulk Fill One) using a mechanical toothbrushing simulation., Methods: Thirty-two samples each of Filtek and TPH were fabricated in ring molds 10 x 1 mm. Samples were randomly grouped (n=8; four groups), according to dentifrice used; Crest 3D, Optic White, Hello (charcoal), and Aim as control. Samples were brushed in mixed solutions containing deionized water and dentifrice at 150 gf for 10,000x with rotation to ensure uniform brushing. Surface roughness was measured both before (baseline) and after the mechanical toothbrushing simulation using a stylus profilometer. Data collected was compared independently for each treatment using two-way ANOVA and SNK with α< 0.05 for significance., Results: The data showed that TPH was more susceptible to the abrasive nature of three of the whitening dentifrices tested [Crest 3D, Optic White, and Hello (charcoal) ]. Filtek also exhibited significant susceptibility to the abrasive nature of Hello. Aim showed the least or minimal amount of abrasion., Clinical Significance: TPH ST composite was more susceptible to the abrasive nature of the three whitening dentifrices tested [Crest 3D, Optic White, and Hello (charcoal)]. Filtek also exhibited significant susceptibility to the abrasive nature of Hello. Aside from the data supporting the clinical efficacy of TPH compared to Filtek, clinicians should inform patients of the abrasive capacity of all whitening dentifrices, especially those that are charcoal based., Competing Interests: The authors declared no conflict of interest. Supported in part by the University of Tennessee Health Science Center College of Dentistry Alumni Endowment Fund and the Tennessee Dental Association Foundation., (Copyright©American Journal of Dentistry.)

Purpose: To determine the efficacy of an oral spray and oral rinses to inhibit oral cariogenic dual species biofilm formation on hydroxyapatite (HA) discs., Methods: The Streptococcus mutans (NCTC 10449, ATCC), Lactobacilli casei (NCIB 8820, ATCC) dual species biofilm formation and inhibition on HA disc was tested using five antimicrobial products, i.e., oral spray (Oral Shield), Mouthrinse (Listerine Ultra Clean, Listerine Cool Mint, Crest Pro-Health, ACT Restoring). An untreated group served as control. The established biofilm on the surface of each disc was treated or untreated with oral spray and mouthrinse for 2 minutes after 24 or 48 hours. The dual species biofilm formation and inhibition on HA discs was determined using the spread plate method and colonies were counted and expressed as colony forming units (CFU/mL). Further, the HA disc was subjected to confocal laser scanning microscope (CLSM) examination to determine the viability of cells using live-dead staining and a scanning electron microscope (SEM) to examine the effect on bacteria biofilm and morphology. The cytotoxic effect of test spray and mouthrinse was tested on OKF6/TERT-2 cells using the MTT method., Results: At each time point, 24- or 48-hours, S. mutans and L. casei mixed biofilm on HA discs had a significantly (P> 0.001) fewer number of bacteria in the treated groups than the untreated one. The oral spray and mouthrinses had a detrimental effect on bacteria biofilm, morphology and cell wall, whereas no significant changes were observed in the untreated group. Cytotoxic assay revealed that the oral spray was safe for human oral keratinocyte cells., Clinical Significance: The tested oral spray could offer potential to inhibit the cariogenic bacteria and protect the tooth enamel from cariogenic bacterial biofilm., Competing Interests: Dr. Azees, Dr. Wang, Dr. Chen and Dr. Yeh have no conflict of interest. Dr. Garcia-Godoy was involved in developing the formulation for the Oral Shield spray., (Copyright©American Journal of Dentistry.)

Purpose: To quantify the biological contamination of a dental operatory environment using a biological tracer., Methods: A Streptococcus mutans suspension was infused into the mouth of a phantom, and an operator performed standardized dental procedures using an air turbine, a contra-angle handpiece, or an ultrasonic scaler either with windows open or closed. The presence of the tracer was measured by placing Petri dishes with a selective medium at 18 sites on the dental unit and 38 sites in the surrounding operatory environment., Results: The contamination was drastically reduced when windows were opened, no matter which handpiece was used. Air turbine spread significantly higher contamination compared to contra-angle and scaler. All tested instruments spread the tracer over the entire dental unit and the surrounding environment, including the walls and ceiling; however, higher contamination levels were detected on the dental unit compared to the operatory surfaces. Opening windows during dental operative procedures greatly reduced contamination levels for all handpieces and can be recommended for reducing airborne contamination levels., Clinical Significance: The significant levels of airborne contamination produced when operating dental handpieces can be significantly reduced by natural ventilation, i.e., simply opening the windows., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate color and gloss changes of three different resin composites after staining and whitening., Methods: 57 disc-shaped composite samples were made for each of three resin composite materials [Activa BioActive Restorative (Activa), Filtek Supreme (Filtek), and TPH Spectra (TPH)], producing 19 samples per composite (n=19). Each group of resin samples was divided among four solutions: red wine, coffee, tea, and water (control), producing six samples per staining group (n=6) and one control (n=1). Samples were stained for 40 days for 3 hours/day at room temperature. When not undergoing staining/whitening, samples were stored in DI water at 37°C. Measurements were obtained for color and gloss before staining, after staining, and after whitening. Illuminant source specular component excluded (SCE) and included (SCI), with both CIE L*a*b* and CIE 2000 L*C*h* systems, were obtained with colorimetric measurements. The standard ΔE (total color change) = 3.3 was used as a clinically acceptable value. Stained groups were divided into two groups (n= 9 each) for each whitening product: Opalescence Boost and Opalescence PF. Both were applied according to manufacturer's instructions., Results: Staining of all samples consistently showed decreased lightness. Filtek showed the most colorimetric changes, especially with wine, while TPH and Activa composites showed few changes; most changes were with tea. Whitening altogether showed generalized increased lightness. All Activa specimens returned to clinically acceptable levels, but the other two materials tested varied. Gloss was most affected for TPH, followed by Filtek; and gloss improved with Activa groups. Overall, Filtek's color varied most, with Activa and TPH being less. All Activa groups returned to clinically acceptable values. However, multiple TPH and Filtek groups had ΔE> 3.3. Furthermore, TPH had the most gloss changes. Activa composites appeared the most stable under the conditions of this study., Clinical Significance: Clinicians should be aware that resin composites can undergo staining from a variety of sources. Some resin composites can return to their original esthetic appearance after using bleaching agents. In addition, staining beverages can affect the gloss of the resin composite., Competing Interests: Dr. Parks and Mr. Morrow declared no conflict of interest. Dr. Pameijer and Dr. Garcia-Godoy are consultants to the Pulpdent Corporation., (Copyright©American Journal of Dentistry.)

Purpose: To examine the effects of an ion-releasing filler-containing gel on the remineralization of dentin using optical coherence tomography (OCT)., Methods: Dentin slabs of bovine teeth were sliced and shaped into a rectangular form. Specimens were treated with undersaturated 0.1 M lactic acid buffer solution (pH 4.75) for 10 minutes and then placed in artificial saliva (pH 7.0). This procedure was repeated three times a day for 28 days. The dentin remineralization effects of a fluoride/S-PRG filler-containing gel (PRG) and a 38% SDF solution (SDF) on dentin slabs of bovine teeth were compared. After treatment, the dentin slabs were immersed in a 0.1 M lactic acid buffer solution and then placed in artificial saliva. This procedure was repeated three times a day for 28 days. OCT imaging was conducted on the selected location of the dentin surface. The peak intensity and width at 1/e² were recorded in each of the six areas on the sample and averaged. Each group had a sample size of 10. Knoop hardness number (KHN) measurements and scanning electron microscopy (SEM) observations were also conducted. The data for each group were subjected to a one-way repeated-measures ANOVA and Tukey tests (α= 0.05). The samples were also observed using SEM., Results: The peak signal intensities of SDF and PRG decreased on day 7 and then slightly increased during the experimental period for the one-off application groups and then decreased for frequent-time application groups. Although the width at 1/e² in the untreated specimens decreased over the test period, SDF and PRG for the one-off application groups exhibited an increase in widths on day 7 followed by a slight decrease, whereas it increased for the frequent-time application groups. The average KHN of the dentin samples exhibited the same tendency as the width at 1/e². Closure of the dentin tubules and crystal precipitation were detected on the surface of both SDF and PRG groups., Clinical Significance: S-PRG filler-containing gel might have the ability to prevent dentin demineralization and could be useful for the prevention of hard-to-access lesions. This material achieved remineralization of the demineralized root dentin and had the same remineralization ability as SDF in vitro., Competing Interests: The authors certify that they have no proprietary, financial, or other personal interest of any nature or kind in any product, service, and/or company that is presented in this article. This work was supported, in part, by Nakao Foundation, Grants-in-Aid for Scientific Research (C) 19K10158, 19K10159, from the Japan Society for the Promotion of Science. This project was also supported, in part, by the Sato Fund, Uemura Yasuo-Haruko Fund, and by a grant from the Dental Research Center of Nihon University School of Dentistry, Japan., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the effect of different substrate stiffness [sound dentin (SD), resin composite core (RC) or metal core (MC)] on the stress distribution of a zirconia posterior three-unit fixed partial denture (FPD)., Methods: The abutment teeth (first molar and first premolar) were modeled, containing 1.5 mm of axial reduction, and converging axial walls. A static structural analysis was performed using a finite element method and the maximum principal stress criterion to analyze the fixed partial denture (FPD) and the cement layers of both abutment teeth. The materials were considered isotropic, linear, elastic, homogeneous and with bonded contacts. An axial load (300 N) was applied to the occlusal surface of the second premolar., Results: The region of the prosthetic connectors showed the highest tensile stress magnitude in the FPD structure depending on the substrate stiffness with different core materials. The highest stress peak was observed with the use of MC (116.4 MPa) compared to RC and SD. For the cement layer, RC showed the highest values in the molar abutment (14.7 MPa) and the highest values for the premolar abutment (14.4 MPa) compared to SD (14.1 and 13.4 MPa) and MC (13.8 and 13.3 MPa). Both metal core and resin composite core produced adequate stress concentration in the zirconia fixed partial denture during the load incidence. However, more flexible substrates, such as composite cores, can increase the tensile stress magnitude on the cement., Clinical Significance: The present study shows that the choice of the cast core and metallic post by the resin composite core and fiberglass post did not improve the biomechanical behavior of the FPD. This choice must be performed based on clinical criteria (other) than mechanical., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate and compare the effect on micro-tensile bond strength (µTBS) of a double layer application of three universal adhesives applied in self-etch mode to proximal dentin/cementum gingival margins of class II direct composite restorations, immediately and after 12 months water storage., Methods: 66 molars with compound class II cavities, with gingival margin 1 mm below CEJ, were divided into three groups according to the universal adhesive used. The adhesives evaluated included All-Bond Universal (AB), Single Bond Universal (SB), and Prime&Bond Elect (PB). The groups were further subdivided according to adhesive application technique, either single layer or double layer application. All teeth were restored with the same nanofilled resin composite. µTBS were examined at a crosshead speed of 0.5 mm/minute after 24 hours or 12 months water storage. Fracture mode was assessed under stereomicroscope. Data were analyzed by two-way analysis of variance (ANOVA) followed by Tukey's post hoc test (P< 0.05)., Results: The double layer application µTBS values were significantly higher than single layer application in all groups. Regardless of the type of adhesive or application technique, all subgroups showed significantly decreased bond strength after aging. There were significant lower µTBS values for AB adhesive compared with the other two adhesives that demonstrated no significant differences between them. The double layer application technique was effective in enhancing µTBS values of all tested adhesives bonded to proximal dentin/cementum gingival margins compared to single layer application. Regardless of application technique, all tested adhesives were incapable of defying long-term water aging., Clinical Significance: The double layer application technique may be recommended to enhance the bonding durability of universal adhesives to face challenges in bonding to dentin-cementum cervical margins., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the ability of a pencil-type transducer connected to a pulser-receiver to measure remaining dentin thickness (RDT)., Methods: A total of 24 freshly extracted bovine incisors were used to prepare dentin disks with certain thicknesses (0.5, 1.0, 1.5 and 2.0 mm). The thicknesses of the specimens were measured with an ultrasonic technique using a pencil-type transducer, and the data obtained were compared with the direct measurement obtained using a micrometer. The Bland-Altman comparison method and paired t-test were performed at a 0.05 significance level., Results: The agreement between different measurement methods was analyzed to evaluate the inter-methodology variation. The Bland-Altman comparison method revealed a mean difference of 0.0098 ± 0.724 mm between the ultrasonic technique and the direct measurement, with the 95% Bland-Altman limits of agreement ranging from 0.1322 to 0.1517 mm., Clinical Significance: Ultrasonic measurement using the pencil-type transducer may be a promising method to evaluate remaining dentin thickness., Competing Interests: The authors declared no conflict of interest. This work was supported in part by Grants-in-Aid for Scientific Research, 19K10158 and 19K10159, from the Japan Society for the Promotion of Science. This project was also supported in part by the Sato Fund and by a grant from the Dental Research Center of the Nihon University School of Dentistry, Japan., (Copyright©American Journal of Dentistry.)

Purpose: To investigate whether the addition of sodium-DNA (Na-DNA) to chlorhexidine (CHX)-containing mouthwash influenced morphology and viability of a reconstituted human oral epithelium (ROE), and protects ROE against oxidative stress., Methods: Multi-layered 0.5 cm² ROE specimens were positioned inside a continuous flow bioreactor and grown air-lifted for 24 hours. They were treated with phosphate-buffered saline (PBS) (n= 16) or 1 vol% H₂O₂ for 1 minute (n= 16). Then, they were treated for 5 (n= 8) or 30 minutes (n= 8) with the experimental mouthwash solutions containing: 0.2 wt% CHX, 0.2 wt% CHX + 0.2 wt% Na-DNA, 0.2 wt% Na-DNA, PBS. After 60 minutes washout specimens were subjected to tetrazolium-based viability assay (MTT) confocal laser-scanning microscopy (CLSM), and histological evaluation using optical microscopy and transmission electron microscopy (TEM)., Results: ROE treated with Na-DNA for 30 minutes revealed significantly higher viability than PBS, and CHX + Na-DNA showed higher viability after 30-minute treatment than after 5 minutes, suggesting a significant protective activity of Na-DNA. Moreover, the protective effect of Na-DNA on cell viability was higher after the induction of oxidative stress. After treatment with CHX, CLSM revealed cell stress, leading to cell death in the outer layer. On the contrary, specimens treated with Na-DNA showed a much lower number of dead cells compared to PBS, both in the absence or presence of oxidative stress. Histological examination showed that the protective action of Na-DNA formulations reached more in-depth into the epithelium exposed to oxidative stress, due to intercellular spaces opening in the outer epithelium layers, giving way to Na-DNA to the inner parts of the epithelium. It can be concluded that Na-DNA had a topical protective activity when applied for 30 minutes unless the epithelium barrier is damaged, allowing it to act more in-depth., Clinical Significance: Na-DNA showed a clear and protective action against cellular degeneration due to oxidative stress and, partly, to the exposure to CHX. Its addition to chlorhexidine mouthwash or gels could be clinically helpful in contrasting the detrimental activity of CHX on oral tissues, and in the preservation of cell viability, control of inflammation and wound healing., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To review the literature on the presence of two clinical manifestations in patients presenting COVID-19 (SARS-CoV-2) infection: loss of taste (ageusia) and loss of smell (anosmia)., Methods: PubMed and EMBASE were searched and studies were selected starting from November, 2019 until April 2020; also, the references of the selected articles were evaluated for methodological quality., Results: Of the 19 studies analyzed, five were included to evaluate the presence of ageusia and/or anosmia as symptoms in patients who were tested and resulted positive for the SARS-CoV-2 virus. In a total of 10,818 patients, 8,823 presented ageusia (81.6%; range 5.6%-88%) and 8,088 presented anosmia (74.8%; range 5.1-85.6%). Only one study recorded both symptoms with a percentage of 18.6%., Clinical Significance: This systematic review demonstrated significant presence of ageusia and anosmia in the patients with COVID-19 infection. These symptoms may be considered as the first manifestation of the infection., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate marginal seal, adaptation, surface texture, and bubble presence of pit and fissure sealants when using a novel instrument (C-Shape It) or the manufacturers' supplied applicators for sealant placement into occlusal fissures., Methods: Extracted molars with occlusal fissures were cleaned with pumice slurry and divided into six groups (n= 10/gp); three treatment and three control. Sealant materials placed included Ultraseal, Delton, and Helioseal. Excess water was removed per manufacturers' instructions. Sealants were applied with each applicator and with the C-Shape It to each group from cusp to cusp without covering marginal ridges, and the polymerization guidelines for photocuring were followed for all the groups. Samples were thermocycled at 500x between 5° and 55°C. Teeth were sectioned in a buccolingual direction with a minimum of four sections per tooth and examined under a light microscope at 50x and scored., Results: Marginal seal, adaptation, penetration ability, surface texture, bubble formation and location of the sealants were analyzed using two-way ANOVA on ranks with a 95% confidence interval. The C-Shape It instrument showed consistently smoother surface texture (P< 0.001), which was statistically significant versus all manufacturers' applicators for all materials. Bubble presence was statistically significantly less with the instrument C-Shape It versus the manufacturers' applicators for all materials (P< 0.001). Results also revealed significant differences in marginal sealant adaptation., Clinical Significance: C-Shape It demonstrated consistent ability to reduce bubbles and improve surface texture and adaptation in occlusal fissures for all pit and fissure products tested., Competing Interests: The authors declared no conflict of interest. Southern Dental Instruments financially supported this study. Southern Dental Instruments was not involved in the study design, collection, analysis, interpretation of data, writing of the report, nor in the decision to submit the article for publication., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the antibacterial efficiency of silver-loaded gelatin sponges prepared from gelatin and silver diamine fluoride, Ag(NH3)2F., Methods: A series of novel silver-loaded gelatin sponges were prepared from gelatin and silver diamine fluoride. They were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The antibacterial activities against one oral bacteria model S. mutans were evaluated using the agar disk diffusion method and biofilm-grown bacteria assay. For the purpose of comparison, a second series of silver-loaded sponges were prepared using silver nitrate (AgNO3) as the silver source., Results: FT-IR, SEM and EDX results confirmed the successful preparation of silver-loaded gelatin sponges from both silver diamine fluoride and silver nitrate. Agar disk diffusion assays revealed that the antibacterial activity of silver-loaded sponges was strongly correlated with the silver content, and also depending on the silver source used in the preparation of sponges. Sustained inhibition of S. mutans in agar plates was observed for silver-loaded gelatin sponges containing about 5 wt% Ag or more. Biofilm assays showed different viabilities when treated with different formulations, with the viability of 11.4±3.1% for the sponges containing 5.30±1.18 wt% Ag prepared from silver diamine fluoride, and the viability of 15.4±3.1% for the sponges containing 29.13±10.34 wt% Ag prepared from silver nitrate., Clinical Significance: The silver loading contents had a significant effect on the antibacterial activities of silver-loaded gelatin sponges prepared with silver diamine fluoride. In addition, silver diamine fluoride was a superior silver source to prepare antibacterial silver-loaded gelatin sponges when compared with silver nitrate., Competing Interests: The authors declared no conflict of interest. This work was partially supported by the UTHSC College of Dentistry Alumni Endowment Fund and the Tennessee Dental Association Foundation., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the biomechanical behavior of monolithic ceramic crowns with functional elasticity gradient., Methods: Using a CAD software, a lower molar received a full-crown preparation (1.5 mm occlusal and axial reduction). The monolithic crown was modeled with a resin cement layer of 0.1 mm. Four groups were distributed according to the full crown elastic modulus (E) :(a) Bioinspired crown with decreasing elastic modulus (from 90 to 30GPa); (b) Crown with increasing elastic modulus (from 30 to 90 GPa); (c) Rigid crown (90 GPa) and (d) Flexible crown (30 GPa). The model was exported to the analysis software and meshed into 385.240 tetrahedral elements and 696.310 nodes. Materials were considered isotropic, linearly elastic, and homogeneous, with ideal contacts. A 300-N load was applied at the occlusal surface and the base of the model was fixed in all directions. The results were required in maximum principal stress criterion., Results: Crowns consisting of layers with increasing elastic modulus presented intermediate results between the rigid and flexible crowns. Compared to the flexible crown, the bioinspired crown showed acceptable stress distribution across the structure with lower stress concentration in the tooth. In dental crowns the multilayer structure with functional elasticity gradient modifies the stress distribution in the restoration, with promising results for bioinspired design., Clinical Significance: The manufacturing of posterior crowns with functional elasticity gradient should be considered due to its promising results on the stress concentration behavior., Competing Interests: The authors declared they had no conflict of interest. The study was supported by the São Paulo Research Foundation (FAPESP) with the grant no. 18/05736-9., (Copyright©American Journal of Dentistry.)

Purpose: To examine the influence of different bulk and block composite and flowable and glass-ionomer material combinations in a multi-layer technique and in a unique technique, in deep Class I dental restorations., Methods: 3D CAD of the sound tooth were built-up from a CT scan dataset using reverse engineering techniques. Four restored tooth models with Class I cavity were virtually created from a CAD model of a sound tooth. 3D-finite element (FE) models were created and analyzed starting from CAD models. Model A with flowable resin composite restoring the lower layer and bulk-fill resin composite restoring the upper layer, model B with glass-ionomer cement (GIC) restoring the lower layer and bulk-fill resin composite restoring the upper layer, model C with block composite as the only restoring material and model D with bulk-fill resin composite as the only restoring material. Polymerization shrinkage was simulated with the thermal expansion approach. Physiologic masticatory loads were applied in combination with shrinkage effect. Nodal displacements on the lower surfaces of FE models were constrained in all directions. Static linear analyses were carried out. The maximum normal stress criterion was used to assess the influence of each factor., Results: Considering direct restoring techniques, models A, B and D exhibited a high stress gradient at the tooth/restorative material interface. Models A and D showed a similar stress trend along the cavity wall where a similar stress trend was recorded in the dentin and enamel. Model B showed a similar stress trend along enamel/restoration interface but a very low stress gradient along the dentin/restoration interface. Model C with a restoring block composite material showed a better response, with the lowest stress gradient at the dentin, filling block composite and enamel sides., Clinical Significance: Bulk resin-based composite materials applied in a multilayer technique to deep and large Class I cavities produced adverse stress distributions versus block resin composite. Polymerization shrinkage and loading determined high stress levels in deep Class I cavities with bulk multi-layer restorations, while its impact on adhesion in block composite restorations was insignificant., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To investigate the infiltration potential of different self-etch adhesives into natural non-cavitated proximal lesions and the effect of dehydration protocol on the infiltration of a self-etch adhesive., Methods: 29 extracted molars and premolars with natural proximal lesions (ICDAS 1-2) were sectioned through the lesion providing two samples from each lesion. To compare the different adhesives, three groups of eight lesions were abraded with fine metallic strips and then etched with 37% H3PO4 acid for 120 seconds. All teeth were stained with rhodamine isothiocyanate. After drying with compressed air and ethanol application, lesions were infiltrated with Scotchbond Universal, Clearfil SE Protect or OneCoat 7 Universal for 180 seconds and then coated with a thin layer of flowable composite (Tetric Flow). To compare the effect of dehydration protocol on infiltration, two groups of nine paired lesions were pretreated as described above. One group was dried using compressed air alone and the second group was dried using compressed air and ethanol, both groups were then infiltrated with Scotchbond Universal then coated with a thin film of flowable composite. After light curing, un-encapsulated dye was bleached by immersion in hydrogen peroxide. Remaining lesion pores were stained with sodium fluorescein solution. Thin cuts of the teeth were observed with confocal microscopy and computer image analysis was performed (ImageJ)., Results: ANOVA and Duncan post-hoc tests showed no significant differences of the infiltrated area between the three adhesives (P= 0.835), no significant difference was found between the group dried with air compared to the one dried with air and ethanol. It can be concluded that the tested adhesives may be used for infiltration of natural lesions following the described pretreatment., Clinical Significance: Enamel pretreatment with metallic strip and 37% H3PO4 acid promotes the infiltration of different adhesives into natural non-cavitated caries lesions., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To compare a new technique of non-invasive proximal adhesive restoration (NIPAR) to the infiltration concept technique (ICON)., Methods: Extracted human posterior teeth with non-cavitated proximal carious lesions (ICDAS code 1-2) were cut vertically to obtain two symmetrical lesions. Group 1 (NIPAR):Half of the paired lesions surfaces (n=13) were abraded with metallic strips and etched with 37% H3PO4 for 120 seconds. Group 2 (ICON):The other half of the paired lesions' surfaces (n=13) were etched with 15% HCl gel for 120 seconds. All samples were then stained with rhodamine isothiocyanate (RITC). After ethanol drying and isolation of the cut surface, Group 1 samples were infiltrated with Scotchbond Universal for 180 seconds and coated with a thin film of Tetric flow. Group 2 samples were infiltrated with ICON infiltrant following manufacturer's instructions. After light curing, unbound rhodamine was bleached by immersion in 30% hydrogen peroxide for 12 hours. Remaining lesion pores were stained with sodium fluorescein solution. Samples were observed with confocal microscopy (CLSM) and the percentage of infiltration (area of resin infiltration/area of total demineralization ×100) was calculated using ImageJ., Results: 11 samples out of 13 showed larger infiltrated area of the lesions in Group 1 (NIPAR) compared to Group 2 (ICON). Statistical analysis revealed a significant difference between the two groups (P< 0.05). Within the limitations of this study, NIPAR allowed for better infiltration of non-cavitated proximal carious lesions when compared to ICON., Clinical Significance: The combination of infiltration and sealing using non-invasive proximal adhesive restoration (NIPAR) offers a suitable non-invasive treatment option for non-cavitated proximal lesions combining the advantages of sealing and infiltration., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To assess the clinical ability of marginal detection of different intraoral optical scanning (IOS) systems., Methods: The Ethics Committee of the University of Siena, Italy approved the research project. Thirty patients in need of an onlay/inlay with supra-gingival margins were included and randomly divided in three groups of 10 (3× n=10) according to the IOS for chairside capturing:(A) GC-Europe (Aadva); (B) True-Definition-TD; (C) Trios. A total of 1 scans from each IOS test group (A-C), were obtained clinically and stored as STL-files. In addition, corresponding conventional impressions were taken for all 30 patients, poured with stone, and then processed by a laboratory scanner (Aadva), serving as controls. All 60 STL-files were imported to the Exocad platform for analysis. The horizontal distance between each preparation margin and the adjacent tooth was measured using the ruler tool in the software. The distance at which the detection of the margin started to become visibly unclear was recorded for the horizontal distances. Data was processed statistically by one-way ANOVA (P> 0.05)., Results: No statistically significant inter-test group differences could be identified (IOS A-C). The minimum distance from which a clear margin was visible, was 4.5 (SD 0.1) mm for all images, regardless of which IOS was used. Under these experimental clinical conditions, all tested IOS performed similarly. In contrast, all margins of the controls were clearly visible., Clinical Significance: None of the tested intraoral scanning systems in this study were capable of recording a clear impression when the cervical margin for a posterior partial crown was located at a distance of less than 0.5 mm from the interproximal neighbor., Competing Interests: The authors declared no conflicts of interest. The work was supported by the Department of Prosthodontics and Dental Materials, School of Dental Medicine, University of Siena, Italy., (Copyright©American Journal of Dentistry.)

Purpose: To compare the sealing effectiveness of four different implant-abutment connections against Staphylococcus aureus (S. aureus). The null hypotheses stated that there was no difference on sealing ability among the implant-abutment connections tested., Methods: Five diverse commercially available dental implants were used to investigate the degree of microleakage at the implant-abutment junction (IAJ): Group 1: Torque Type conical implant with double conic connection - TTc (Winsix); Group 2: Torque Type conical implant with Cone Morse connection - TTcm (Winsix); Group 3: Free Lock connection - K type implant (Winsix); Group 4: Internal double hexagon - OsseoSpeed; Group 5: Internal hexagon - Aadva Implant. Nine implants were tested in each group and one group was used as the negative control (Group 4). The abutments were connected to implants according to manufacturers' recommendations. All procedures involving connection and disconnection of implants were performed in sterile conditions in a laminar flow biological safety cabinet. S. aureus ATCC 6538, a methicillin susceptible reference strain, was chosen for the experiments to test the degree of microleakage. Statistical analysis was performed in order to find significant differences among the five groups regarding sealing capability of the implant-abutment connections tested. The recorded data were statistically analyzed., Results: One implant from Group 4 was excluded from the study because of the growth of a contaminant after 48 hours of incubation in all three wells (i.e. Paenibacillus pabuli, environmental Gram-positive bacteria). Wells A and B (i.e. wells where the samples were passed before being located in the final well C) of all other samples (n = 46) remained sterile over the 72 hours of incubation, indicating the lack of external contamination during implant-abutment connection. Similarly, no bacterial growth was observed in the five negative controls (i.e. one implant for each type), which had been inoculated with sterile saline and processed as the others. Bacterial microleakage was demonstrated with three samples, including one sample of Group 1, one of Group 3 and one of Group 5, in which growth of S. aureus in wells C after 48 hours of incubation was demonstrated (Table 1). No statistically significant difference between groups was noticed (P> 0.05)., Clinical Significance: Within the limitations of the present in vitro model, the results obtained suggest a tendency toward a better sealing capability for conical connections and internal hexagon., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To investigate the feasibility of exploiting amorphous calcium phosphate (ACP) formed in situ from chitosan calcium microspheres and phosphate ions in water during brushing for caries control., Methods: A prototype toothpaste, namely Chi-ACP paste, was specially formulated containing CaCl₂/chitosan microspheres. The efficiency of Chi-ACP paste for remineralization on human tooth enamel was evaluated via an in vitro pH cycling approach. After 15 demineralization/remineralization cycles, the treated teeth were analyzed using scanning electron microscope (SEM) /energy dispersive X-ray spectroscopy (EDX), and polarized light microscope (PLM)., Results: EDX analysis showed the treated enamel in the Chi-ACP paste group had statistically significantly higher calcium content and Ca/P weight ratios than those in the negative control group, while the MI plus group had a slightly higher Ca content and a slightly higher Ca/P weight ratio. PLM analysis revealed that the Chi-ACP paste group had a larger remineralization band in treated enamel than the negative control group, although there was no statistically significant difference on the demineralization depths in the enamel among the three groups., Clinical Significance: Antibacterial chitosan could be used to encapsulate CaCl₂ and then formulated into toothpaste for caries control through in-situ formed amorphous calcium phosphate (ACP) during brushing., Competing Interests: Drs. Hong, Hottel and Garcia-Godoy are the inventors of a pending U.S. patent held by the University of Tennessee Research Foundation. This pending patent is related to the technology of Chitosan-ACP. Otherwise, the authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)