Tooth Specimens Research Articles

Understanding the hierarchical structure of collagen fibers of the human periodontal ligament: Implications for biomechanical characteristics

The periodontal ligament (PDL) is a unique fibrous connective tissue that regulates periodontal homeostasis mechanisms. Its biomechanical properties primarily reside in the hierarchical and non-uniform collagenous network. This study aimed to investigate the region-specific structure and composition of collagen fibers in the PDL at various scales and to explore their relationship with mechanical properties in a split-mouth design. Fresh human cadaver transverse PDL specimens of maxillary anterior teeth were categorized into cervical, middle, and apical groups. These specimens were analyzed via Masson’s trichrome staining, scanning electron microscopy, picrosirius red (PSR) staining, three-dimensional (3D) reconstruction, Raman spectroscopy, and uniaxial tensile test. Statistical analyses were performed to compare the structural, compositional, and tensile properties among the groups. Notably, the middle PDL samples exhibited superior tensile strength and higher fiber area fraction than the other two transverse sections. Despite a higher mineral-to-matrix ratio and a different collagen secondary structure, the apical PDL demonstrated a relatively weaker tensile strength, possibly associated with its discovered sparser collagen fiber areal fraction. The cervical region, characterized by a mediocre fiber areal fraction, displayed diminished tensile strength. The 3D reconstructed collagenous network model and PSR staining exposed the fiber interaction and the micropores. Microscale porosity and variations in collagen secondary structure, particularly in the apical region, suggest adaptive mechanisms for accommodating compressive forces and maintaining functional integrity. Variance in the tensile properties of samples in different force directions indicated the significant influence of fiber orientation and root level on tissue mechanics. Statement of significanceThis study provides critical insights into the biomechanical and structural properties of the human periodontal ligament (PDL), particularly focusing on the underexplored anterior teeth. Through advanced techniques like SEM, histological staining, 3D reconstruction, Raman spectroscopy, and tensile testing, we reveal significant regional variations in PDL collagen organization, composition, and biomechanical properties. Our findings address a crucial knowledge gap concerning the material mechanics of the PDL, offering a foundational understanding for future periodontal tissue engineering and biomimetic material development. This multi-scale analysis underscores the importance of both mesoscale structural characteristics and nanoscale molecular structures in maintaining PDL mechanical integrity.

The color stability of artificial white spot lesions treated with resin infiltration after exposure to staining beverages

BackgroundTo evaluate the effect of staining beverages on the color-changing of resin-infiltrated artificial white spot lesions (WSLs).MethodsThirty-five artificial WSLs were created by pH cycling on flat bovine teeth specimens. The WSLs were treated with resin infiltration and were divided into five groups based on staining beverages: artificial saliva, coffee, wine, green tea, and Coca-Cola. These specimens were subjected to a 28-day exposure to the respective beverages. Color stability was assessed using a spectrophotometer at different time points: baseline, after 7, 14, 21, and 28 days of exposure, and repolishing. The color difference (∆E) between each time point and the baseline was calculated. Statistical analysis was performed using two-way measures ANOVA with a significance level of p = 0.05.ResultsAll resin-infiltrated specimens exposed to staining beverages for 7 days exhibited more significant color changes than those exposed to artificial saliva. The color change patterns varied based on the type of beverage. The color alterations intensified with extended immersion in the wine and Coca-Cola groups, while there were no significant differences in the color of specimens after 28 days of immersion in the coffee and green tea groups. However, after cleaning with pumice powder, all specimens showed significantly reduced color changes compared to those observed after 28 days of immersion, except those immersed in coffee.ConclusionsExposure of resin-infiltrated bovine tooth specimens to staining beverages resulted in a significant color alteration as the immersion time increased. However, the staining effect could be minimized by cleaning with pumice powder, except for the coffee group.Clinical relevanceAfter resin infiltration treatment, patients should be advised to minimize the consumption of colored beverages to prevent staining that could impact esthetic appearance.

Impact of acidic beverages on composition and surface characteristics of human teeth: scanning electron microscopic, stereomicroscopic and energy dispersive x-ray analyses

ObjectivesThe objective of this study was to evaluate the effect of acidic beverages on the surface topography and elemental composition of human teeth.MethodsA total of five highly acidic beverages (Red Bull, Pepsi, Apple Cidra, Tang Mosambi, and Tang Orange) were investigated. The tooth specimens of experimental groups were submerged in each beverage and incubated at 37 °C for 7 days, whereas, the tooth specimens of control groups were placed in distilled water. Afterwards, tooth specimens were analyzed using scanning electron microscopic (SEM), stereomicroscopic, and energy dispersive x-ray (EDX) techniques.ResultsAll experimental groups revealed a decline in the tooth elements compared to controls, however, such decline was not statistically significant. Nevertheless, comparing the experimental groups, the Red Bull beverage caused a marked reduction in the percentage of both calcium and phosphorus elements compared to the Pepsi, Apple Cidra, Tang Mosambi, and Tang Orange beverages but it was insignificant as well in contrast to its control counterpart. All five acidic beverages demonstrated erosive potential under SEM analysis; however, each group of specimens showed a diverse amount of demineralization. In addition, all experimental groups exhibited significant discoloration of tooth specimens compared to their respective control counterparts.ConclusionsWithin the limitations of study, all five acidic beverages demonstrated erosive potential in the simulated in vitro conditions under SEM analysis; however, each group of specimens exhibited a different extent of demineralization. In addition, the overall effect of all beverages was insignificant under EDX analysis as no substantial difference was revealed between the elemental composition of experimental and control group specimens.

Assessing the impact of the effect of ozone, casein phosphopeptide–amorphous calcium phosphate, silver diamine fluoride, and hydroxyapatite on remineralization of early carious lesions: An investigation using polarized light microscopic study

Abstract Introduction: A popular trend in dental offices, minimal intervention dentistry emphasizes using the least invasive treatments possible to minimize tissue loss and patient discomfort. The earliest indications of dental caries are white spot lesions that can remineralize. Thus, the effects of four different remineralizing agents on early carious lesions were assessed using polarized light microscopy. Materials and Methods: Teeth specimens were immersed in demineralizing agents to create subsurface demineralization. Subsequently, they were randomly assigned to various remineralization regimens, including ozonated water, casein phosphopeptide–amorphous calcium phosphate (CPP-ACP), silver diamine fluoride (SDF), and hydroxyapatite. Each specimen underwent treatment twice daily for 3 min and was then placed in artificial saliva. Mineral content was evaluated at baseline, after demineralization, and during remineralization (on the 7th and 14th day) using a polarized microscopic examination. Results: Group 1 demonstrated the most effective remineralization, consistently displaying the lowest lesion depths at both the 7th and 14th days. Post hoc comparisons indicate significant differences between group 1 and other groups, emphasizing the potential superiority of the remineralization process in group 1 compared to the other treatment groups. Conclusion: Tooth samples treated with ozonated water, followed by CPP-ACP, SDF, and hydroxyapatite demonstrated a more profound level of remineralization. These agents, namely ozonated water, CPP-ACP, SDF, and hydroxyapatite, prove to be effective in reversing the early stages of enamel caries. The following core competencies are addressed in this article: Practice-based learning and improvement, Patient care and procedural skills, Systems-based practice, Medical knowledge.

Influence of bottled salad dressings on the development of enamel erosion in the presence or absence of salivary pellicle – An in vitro study

BackgroundAcidic beverages are believed to elevate the risk of enamel surface erosion. In addition to the intake of soft drinks, the increased consumption of salad dressings has been linked to a higher prevalence of dental erosion. Therefore, the current study aimed to investigate the influence of bottled salad dressings on the development of enamel erosion in the presence or absence of pellicle through in vitro experiment. MethodsPreliminary pH and calcium analyses of solutions were performed. Highest pH and calcium content was found for sandwich spread i.e., 4.69 and 55.4 mg/100 g grams, respectively. Eighty tooth specimens (measuring 4 × 4 × 3 mm) were prepared from extracted human premolars and randomly assigned to four groups (group 1: orange juice; group 2: eggless plain mayonnaise; group 3: sandwich spread; and group 4: thousand island dressing) with 20 samples in each group. Ten tooth specimens from each group were immersed in 20 ml of the respective solutions for 5 min (control group). The remaining ten tooth specimens from each group were submerged in 5 mL saliva vials for 3 min to facilitate salivary pellicle formation before being immersed in their respective solutions for 5 min (saliva-covered group). Pre and post-experimental assessments of enamel roughness and hardness were conducted using a surface roughness tester and Knoop Hardness indenter, respectively. ResultsOverall, enamel roughness was notably elevated in the control group, with the eggless plain mayonnaise (0.52 ± 0.38) and thousand island dressing groups (0.57 ± 0.29) showing a significant increase in surface roughness post-test (p = 0.05). Nevertheless, there was no significant difference in the enamel roughness between the groups. On the other hand, regardless of the presence/absence of the salivary pellicle, a marked decrease in enamel hardness was observed among all groups except for group 3 (sandwich spread) with a mean score of 311.5 ± 82.6 (p < 0.05). ConclusionA significant increase in surface roughness and reduction in enamel hardness was observed with salad dressings. However, in vitro formed salivary pellicle showed a protective effect against tooth erosion.

Dent versus mèche de cheveux. Quelle matrice utiliser pour documenter une exposition répétée ? À propos d’un cas impliquant l’aripiprazole

In recent years, remarkable advances in sensitive analytical techniques have enabled the analysis of drugs in unconventional biological specimens such as oral fluid, sweat or hair. However, other matrices, including tooth, deserve attention as they can be the unique remain on a crime scene. The authors present here the comparison between tooth and hair specimens collected from a long-term subject under aripiprazole therapy (5 mg per day). Tooth was collected during a standard consultation for removal of wisdom tooth. At the same time, after oral consent, a strand of hair (blonde in colour) was collected from a 19-year-old man. After careful elimination of organic material, the tooth was pulverized in a ball mill and 20 mg were incubated under alkaline conditions (pH 8.4) followed by a mixture of organic solvents. After decontamination by dichloromethane, the hair was segmented, cut into very small segments (< 1 mm), overnight incubated in buffer and 20 mg were extracted by a mixture of organic solvents. Drugs were tested by LC/MS-MS. Aripiprazole was identified by 2 ion transitions (m/z 450.2 > 287.1 and 450.2 > 98.0). Aripiprazole was identified in the tooth at 1.4 pg/mg. The drug tested also positive in the 3 x 3 cm segments, at 3.5, 3.9 and 2.6 ng/mg. The concentrations of aripiprazole in the hair segments were in a 1000-fold magnitude when compared to what was measured in the tooth. Although there is an interest to test for drugs in tooth when this element is the unique remain of a cadaver, this approach cannot overrule the interest of hair to document long-term drug exposure. Tooth preparation is tedious and the measured concentration is close to the limit of quantitation. In addition, the window of drug detection in tooth remains unknown at this time.

Assessments of polymerization shrinkage by optical coherence tomography-based digital image correlation analysis—Part I: Parameter identification

ObjectiveTo investigate the feasibility of optical coherence tomography (OCT)-based digital image correlation (DIC) analysis and to identify the experimental parameters for measurements of polymerization shrinkage. MethodsClass I cavities were prepared on bovine incisors and filled with Filtek Z350XT Flowable (Z350F). One OCT image of the polymerized restoration was processed to generate virtually displaced images. In addition, the tooth specimen was physically moved under OCT scanning. A DIC software analyzed these virtual and physical transformation sets and assessed the effects of subset sizes on accuracy. The refractive index of unpolymerized and polymerized Z350F was measured via OCT images. Finally, different particles (70–80 µm glass beads, 150–212 µm glass beads, and 75–150 µm zirconia powder) were added to Z350F to inspect the analyzing quality. ResultsThe analyses revealed a high correlation (>99.99%) for virtual movements within 131 pixels (639 µm) and low errors (<5.21%) within a 10-µm physical movement. A subset size of 51 × 51 pixels demonstrated the convergence of correlation coefficients and calculation time. The refractive index of Z350F did not change significantly after polymerization. Adding glass beads or zirconia particles caused light reflection or shielding in OCT images, whereas blank Z350F produced the best DIC analysis results. SignificanceThe OCT-based DIC analysis with the experimental conditions is feasible in measuring polymerization shrinkage of RBC restorations. The subset size in the DIC analysis should be identified to optimize the analysis conditions and results. Uses of hyper- or hypo-reflective particles is not recommended in this method.

Application of deep learning in isolated tooth identification

BackgroundTeeth identification has a pivotal role in the dental curriculum and provides one of the important foundations of clinical practice. Accurately identifying teeth is a vital aspect of dental education and clinical practice, but can be challenging due to the anatomical similarities between categories. In this study, we aim to explore the possibility of using a deep learning model to classify isolated tooth by a set of photographs.MethodsA collection of 5,100 photographs from 850 isolated human tooth specimens were assembled to serve as the dataset for this study. Each tooth was carefully labeled during the data collection phase through direct observation. We developed a deep learning model that incorporates the state-of-the-art feature extractor and attention mechanism to classify each tooth based on a set of 6 photographs captured from multiple angles. To increase the validity of model evaluation, a voting-based strategy was applied to refine the test set to generate a more reliable label, and the model was evaluated under different types of classification granularities.ResultsThis deep learning model achieved top-3 accuracies of over 90% in all classification types, with an average AUC of 0.95. The Cohen’s Kappa demonstrated good agreement between model prediction and the test set.ConclusionsThis deep learning model can achieve performance comparable to that of human experts and has the potential to become a valuable tool for dental education and various applications in accurately identifying isolated tooth.

To check the antibacterial efficacy against Enterococcus faecalis by various ayurvedic oils used as a solvent in endodontic sealers - An in vitro study

Aim: The aim of the study is to check the antibacterial efficacy of various ayurvedic oils used as a solvent with zinc oxide for preparing endodontic sealers. Materials and Methods: Forty-five extracted premolars were taken and were cut coronally and apically such that 7 mm of tooth specimen was prepared. Teeth were sterilized by autoclaving inoculated with Enterococcus faecalis and incubated for 24 h. The specimens were divided into three groups of 15 each. Group 1 – ZnO powder + Eugenol, Group 2 – ZnO powder + Aremidadi Oil, and Group 3 – ZnO powder + Dashmool oil. Bacterial growth in each specimen was calculated before and after sealer application and noted as the initial and final colony count. The antimicrobial effect of each sealer was measured by calculating the percentage reduction in colony count (%). One-way analysis of variance and post hoc tests will be used for statistical analysis. Results: The Zn + Arimedadi oil group showed the maximum antibacterial effect among the sealers tested and the Zn + eugenol sealer showed the least antimicrobial effect In comparison, there was a statistically significant difference between all the groups. Conclusion: Ayurvedic oil-based root canal sealers showed better antibacterial efficacy than eugenol-based sealers. Arimedadi oil showed the highest antibacterial activity against E. faecalis and Eugenol showed the least when used as a solvent.

Shear bond strength of ultraviolet-polymerized resin to 3D-printed denture materials: Effects of post-polymerization, surface treatments, and thermocycling.

The purpose of this study is to compare the shear bond strength of ultraviolet (UV)-polymerized resin to 3D-printed denture materials, both with and without post-polymerization. Moreover, the effects of surface treatment and thermocycling on shear bond strength after post-polymerization were investigated. Cylindrical 3D-printed denture bases and teeth specimens were prepared. The specimens are subjected to two tests. For Test 1, the specimens were bonded without any surface treatment or thermal stress for comparison with and without post-polymerization. In Test 2, specimens underwent five surface treatments: untreated (CON), ethyl acetate (EA), airborne particle abrasion (APA) with 50 μm (50-APA) and 110 μm alumina (110-APA), and tribochemical silica coating (TSC). A UV-polymerized resin was used for bonding. Half of the Test 2 specimens were thermocycled for 10,000 cycles. Shear bond strength was measured and analyzed using Kruskal-Wallis and Steel-Dwass tests (n = 8). In Test 1, post-polymerization significantly reduced shear bond strength of both 3D-printed denture materials (P < 0.05). No notable difference was observed between the denture teeth and the bases (P > 0.05). In Test 2, before thermocycling, the CON and EA groups exhibited low bond strengths, while the 50-APA, 110-APA, and TSC groups exhibited higher bond strengths. Thermocycling did not reduce bond strength in the latter groups, but significantly reduced bond strength in the EA group (P < 0.001). Post-polymerization can significantly reduce the shear bond strength of 3D-printed denture materials. Surface treatments, particularly APA and TSC, maintained bond strength even after thermocycling.

Effect of a modified methyl methacrylate-p-styrene sulfonic acid copolymer-based gel desensitizer on dentin permeability and tubule occlusion in human dentin in vitro

Background/purposeTubular occlusion is an effective method to treat dentin hypersensitivity. This study aimed to determine the effect of a modified methyl methacrylate-p-styrene sulfonic acid copolymer-based gel desensitizer on dentin permeability and tubule occlusion in extracted human premolars. Materials and methodsHydraulic conductance (HC) measurement (n = 50) and scanning electron microscopy (SEM; n = 64) were performed. Tooth specimens were divided into 6 groups and treated with: G1, distilled water for 30 s; G2, distilled water for 5 min; G3, gel desensitizer for 30 s; G4, gel desensitizer for 5 min; G5, 3% potassium oxalate for 30 s; G6, 3% potassium oxalate for 5 min. HC of dentin were measured before and after 30 s-etching with 35% phosphoric acid, at 0, 30, 60 min after group treatment and after 5-min acid challenge with 6% citric acid. The degree of tubule occlusion and the penetration depth of each agent were also determined. ANOVA and multiple comparison tests were used for data analysis. ResultsG3, G4, G5 and G6 significantly decreased in HC after group treatment every observation period, compared to after acid-etching (P < 0.001), and had 100% degree of tubule occlusion with penetration depth about 7.62, 7.94, 8.59 and 8.66 μm, respectively. However, G6 showed the greatest reduction in HC (P < 0.05). ConclusionGel desensitizer treatment, for only 30 s, could reduce dentin permeability and completely occlude the dentinal tubules, even though after acid challenge. However, 5-min treatment with potassium oxalate showed the greatest decrease in dentin permeability.

A Comparative Evaluation of the Remineralization Potential of Two Contemporary Bioactive Glass-containing Dentifrices on Artificially Demineralized Human Enamel: An In Vitro Study.

There is limited literature comparing the remineralization potential of these two dentifrices, Elsenz™, which contains fluoro calcium (Ca) phosphosilicate, and Shy-NM™, which contains Ca sodium phosphosilicate, are a few of the remineralizing agents. To assess and compare the remineralization potential of Elsenz™ and Shy-NM™ dentifrices on artificially induced carious lesions on permanent teeth, using the Vickers microhardness measuring method and scanning electron microscope (SEM) connected to energy dispersive X-ray analysis after laboratory stimulation of the oral environment employing the pH cycling model. A total of 30 sound human premolar teeth were divided into six groups for both parameters. Group I-Elsenz™ dentifrice, group II-Shy-NM™ dentifrice, and group III-control. The surface microhardness (SMH) of the test specimens was evaluated followed by a scanning electron microscope with energy dispersive analysis (SEM-EDAX). The specimens were tested at baseline, demineralization, and remineralization. The collected data were subjected to statistical analysis. Surface microhardness following remineralization with Elsenz™ was 359 Vickers hardness number (VHN), and with Shy-NM™ was 312 VHN. Elsenz™ showed significantly higher remineralization compared to Shy-NM™ (p = 0.002). The SEM-EDAX of the tooth specimens after remineralization revealed an increase in the Ca weight percentage (wt%) compared with demineralization values, which was statistically significant for both Elsenz™ (45.95 ± 3.55%) and Shy-NM™ (47.24 ± 1.99%), along with an increase in the phosphorus wt%, which was statistically significant for Elsenz™ (20.25 ± 0.95%) compared to Shy-NM™ (19.95 ± 0.59%). Within the scope of this study, the incorporation of fluoride in bioactive glass (BAG) in Elsenz™ had the potential to remineralize enamel better than Shy-NM™ dentifrice. It can, therefore, be concluded that Elsenz™, when compared with Shy-NM™, would be effective in inhibiting demineralization. Thoutam SV, Kumar S, Naidu J. A Comparative Evaluation of the Remineralization Potential of Two Contemporary Bioactive Glass-containing Dentifrices on Artificially Demineralized Human Enamel: An In Vitro Study. Int J Clin Pediatr Dent 2024;17(4):451-455.

In Vitro Evaluation of Remineralization Potential: Whey Extract, Fluoride Varnish, and Fluoride Mouthwash on Bleached Enamel

Background: Extrinsic discoloration is treated with bleaching which increases enamel porosity and roughness. Remineralizing materials is applied to avoid the bleaching side effects. The current study aimed to evaluate time dependent safety of bleaching materials on enamel surfaces roughness, and to assess the remineralizing potential of whey extract as a natural product and to compare it with the commercially available fluoride varnish and fluoride mouthwash after maximum bleaching time (30 min.). Methods: Extracted human incisor teeth without cracks or any enamel defects were used in this study. Teeth were cleaned and decoronated at the level of the cementoenamel junction. A nail varnish was used to cover the entire surface of the crowns of each tooth, leaving a window measuring 4 mm × 4mm. Bleaching material was applied to the enamel of all teeth specimens. The Application of bleaching material was repeated 2 more times, each time for 10 minutes, which amounted in total to 30 min. The specimens in group 1 were soaked in artificial saliva, the specimens in group 2 were soaked in whey extract, the specimens in group 3 were treated with fluoride varnish and group 4 specimens were soaked in fluoride mouthwash. Results: The mean value of the surface roughness of all the teeth specimens was increased significantly after bleaching for 10 minutes, 20 minutes and 30 minutes (p=0.000) when compared with baseline mean value. As well, there was significant direct correlation between application time of bleaching material and mean value of surface roughness (r= 0.94). There were no significant differences (p&gt;0.05) between the specimens of the 4 groups when the mean value of surface roughness compared at baseline and after bleaching. But, after treatment, there was significant difference (p≤0.05) between the 4 groups, with the best result obtained from whey extract and fluoride varnish. Conclusions: The enamel surface roughness is significantly and directly correlated with prolonged application time of bleaching material. Remineralizing materials; whey extract, fluoride varnish and fluoride mouth wash had significantly decreased enamel surface roughness caused by bleaching. Whey extract has statistically the same effect as fluoride varnish on decreasing the surface roughness of bleached enamel surface.

Evaluation of Bond Strength of Three Glass Fiber Post-systems Cemented to Large Root Canals.

The aim of this study was to evaluate the push-out bond strength and the failure mode of single adjustable posts (SPLENDOR SAP), anatomical posts (AP), or computer-aided design/computer-aided manufacturing (CAD-CAM) posts cemented to flared root canal dentin with self-adhesive dual-cure resin cement. Thirty single-rooted premolars received endodontic treatment with gutta-percha and a calcium hydroxide-based endodontic cement. After 24 hours, the canal spaces were enlarged with burs. The tooth specimens were divided equally into three groups (n=10), according to the glass fiber post (GFP) system: AP-prefabricated GFP (Reforpost #2, Angelus) was relined with composite resin (Filtek Z350 XT, 3M ESPE); SPLENDOR SAP-GFP was used with a glass fiber sleeve to adjust the adaptation (Splendor SAP, Angelus); and CAD-CAM-a resin pattern was obtained and scanned to produce a CAD-CAM GFP (Fiber CAD Lab, Angelus) milled using a subtractive technique. The three GFP systems were cemented with self-adhesive resin cement (Rely X U200, 3M ESPE). The roots were fixed to an acrylic resin plate used to section them into specimens of cervical, middle, and apical thirds. Then, the slices were attached to a universal testing machine to perform the push- out test at a speed of 0.5 mm/min and a load of 50 Kgf. The posttest specimens were examined under a stereoscopic microscope to evaluate the failure mode. The bond strength variable was analyzed using a generalized linear model, following a split-plot design. Failure mode analysis was performed using Fisher exact test. The significance level adopted was 5%. There was no significant difference among the GFP systems or among the thirds, in terms of bond strength (p>0.05), nor was there any significant association between the systems and the failure mode (p>0.05). Most specimens presented mixed or adhesive failure between resin cement and dentin. It was concluded that the bond strength to flared root dentin was not influenced by the GFP system or the root third.

Modern methods and materials used to treat root perforation: effectiveness comparison

This study aims to experimentally compare the efficacy of different endodontic materials (iRoot BP Plus, Biodentine, MTA, Rootdent, and Trioxide) in the treatment of pulpitis and perforations on extracted tooth specimens. Additionally, the study aims to investigate the influence of iRoot BP Plus endodontic material on the regenerative processes following pulp amputation in laboratory animals. The secondary goal is to evaluate the effect of iRoot BP Plus on the restoration process in laboratory animals after pulp removal. The study presents a micropermeability analysis of the selected biomaterials performed on a sample of 50 single-rooted apical teeth in 2022. All teeth underwent endodontic treatment. Changes in molar morphology were investigated with eight laboratory animals (rabbits, 3 months old, all males) after simulated pulp removal and subsequent treatment with the iRoot BP Plus biomaterials. iRoot BP Plus appeared to be more effective in retrograde apical root filling than other biomaterials, as evidenced by its higher sealing effect. An experiment involving animal participants revealed the presence of protective adaptive mechanisms, which manifested in the form of an inflammatory process within 6 weeks after the dental pulp was removed. The connective tissue replaced the necrosis, and new capillaries began to form intensively. These dental outcomes suggest that iRoot BP Plus enables hermetical sealing in tooth restoration with good adhesion. Thus, it may have the ability to promote more active tissue regeneration after pulp removal.Graphical

Inhibition of incipient caries lesion progression by different fluoridated varnishes.

The aim of this in vitro study was to evaluate the potential of different fluoridated varnishes to inhibit the progression of incipient caries lesions after cariogenic challenge. Seventy-five enamel specimens of bovine teeth were prepared and selected based on the initial surface microhardness (SMH). The specimens were first subjected to artificial demineralization (in buffer solution) after which SMH was re-analyzed (SM1). They were then randomly assigned to five experimental groups: 1- CONTROL (pH cycling), 2 - MI VAR (MI Varnish with RECALDENTTM - CPP-ACP), 3 - PROFL (Profluorid®), 4 - CLIN (ClinproTM White Varnish with TCP), and 5 - DUR (Duraphat®) (n=15). The varnishes were applied in a thin layer and the specimens were then subjected to pH cycling for eight days. The SMH and cross-sectional microhardness (CSMH) were then analyzed (SM2). The fluoride and calcium ion concentrations in the solution were analyzed by the indirect method and atomic absorption spectrophotometry, respectively. Data were statistically analyzed by Student's t-test, ANOVA/Tukey-Kramer, or Kruskall-Wallis/Dunn tests for individual comparisons (p˂0.05). All varnishes led to significantly higher surface and subsurface remineralization compared with the control group but did not differ from each other. The varnishes with the highest fluoride release were: PROFL and CLIN, followed by MI VAR and DUR. The varnishes with significantly higher release of calcium were: DUR, CLIN, and PROFL. In conclusion, all commercial fluoridated varnishes tested have good potential to inhibit the progression of demineralization, regardless of the ion release mechanisms.

Effect of incorporation of calcium polyphosphate sub-microparticles in low-concentration bleaching gels on physical properties of dental enamel.

To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs). A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test. The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05). The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy.

Comparative evaluation of wear resistance between lithium disilicates and polymer infiltrated ceramics manufactured by computer aided design (CAD) computer aided manufacturing (CAM) against natural tooth enamel

Advances in CAD/CAM technology led to development of monolithic all ceramic restorations with superior esthetics like Lithium disilicate. But the major concern of ceramic materials was its wear towards the opposing enamel. Polymer infiltrated ceramics were developed by incorporating resin polymer in ceramics to produce esthetic stability of ceramics and low abrasive nature of composites and very few studies were done on this material. A total of 30 disc specimens were fabricated by CAD/CAM .15 discs of CAD/CAM lithium disilicate (IPS E.max CAD) and 15 discs of Polymer infiltrated ceramics of dimensions 10mmx3mm. They were named as group 1 (CAD/CAM Lithium disilicate) and group 2(Polymer infiltrated ceramics). 30 tooth specimens were mounted on auto polymerising acrylic resin blocks. Tooth specimens were placed on the upper member of the two body wear testing machine (Pin on disc wear and friction test rig, Magnum) and Lithium disilicate and polymer infiltrated ceramic disc specimens were positioned on disc of wear testing apparatus under constant load of 5kg (49N). The specimens were made to rub against one another in a rotating cycle to simulate oral wear cycle. The test was run for total of 10,000 wear cycles at 30rpm on wear machine for each sample. Wear of group 1 and group 2 and enamel wear of group 1 and group 2 was measured before and after wear test by profile projector.Wilcoxon test was done to compare the groups. Results showed that wear was greater in group 1 (Polymer infiltrated ceramics) compared to group 2 (CAD/CAM Lithium disilicate) and enamel wear of group 1 was greater than enamel wear of group 2. Advances in CAD/CAM technology led to development of aesthetic all ceramic restorations with superior mechanical properties such as CAD/CAM Lithium disilicate. But the major concern of ceramic materials is wear towards the opposing enamel. To meet the above requirements polymer infiltrated ceramics are developed by incorporating resin polymer in ceramics to produce esthetic stability of ceramics and low abrasive nature of composites. The restorative materials should not cause wear to opposing enamel and also should possess wear resistance similar to enamel for its success and longevity. This study was performed to evaluate the wear resistance of CAD/CAM lithium disilicate and Polymer infiltrated ceramics against natural teeth enamel.

Disinfection Efficacy of Laser Activation on Different Forms and Concentrations of Sodium Hypochlorite Root Canal Irrigant against Enterococcus faecalis in Primary Teeth.

Photoactivated disinfection with sodium hypochlorite (NaOCl) has improved primary root canal treatment outcomes. This in vitro study aims to assess and compare the disinfecting efficacy of 2.5% sodium hypochlorite solution and 5.25% sodium hypochlorite gel, without laser activation and accompanied by laser activation, on Enterococcus faecalis-contaminated primary teeth root canals. After one month of incubating extracted teeth specimens with E. faecalis, 36 specimens were randomly divided into two groups: Group A (conventional method without laser-activated irrigation) and Group B (with laser-activated irrigation). Each group was further divided into three subgroups, with six samples in each subgroup. Subgroup 1 received irrigation with normal saline, Subgroup 2 with 2.5% sodium hypochlorite solution, and Subgroup 3 with 5.25% sodium hypochlorite gel. Diode laser activation at 810 nm was used in Group B. Bacterial colony counts were measured before and after the intervention. Student's t-test and one-way analysis of variance (ANOVA) with Tukey's post hoc test were used for statistical analysis. The significance level was set at p < 0.05. Microbial analysis revealed no bacterial growth in samples irrigated with 5.25% sodium hypochlorite gel activated with the laser. Activation with the laser significantly (p = 0.02) improved the disinfection ability of the irrigant compared to the non-activation group. The disinfection ability of sodium hypochlorite gel was better than that of saline (p = 0.02); however, it was comparable to that of sodium hypochlorite solution (p = 0.67). Conclusion: Root canal irrigation with 5.25% sodium hypochlorite gel activated with an 810 nm diode laser resulted in complete eradication of Enterococcus faecalis, indicating its effectiveness as an endodontic disinfection treatment modality.

A new geographical record of Abelisauridae (Theropoda, Dinosauria) for the Bauru Group (Upper Cretaceous)

Theropod teeth allow high-rank group assignments based on both phylogenetic positioning and morphometry. To the Bauru Group, abelisaurid distribution is known mostly from isolated teeth from relatively few localities. Based on teeth we extend their distribution to Ituiutaba, NNE of the basin. Teeth specimens from the neighboring Prata county, historically attributed to Carcharodontosauridae and Abelisauridae were also analyzed. For taxon assignment, we used methods such as phylogenetic, discriminant analysis, and direct comparisons. In our phylogenetic analysis, all teeth were recovered within abelisaurids whereas in the discriminant analyses, they nested close or within abelisaurids, neovenatorids, and dromaeosaurids. Therefore, our analyses support that teeth from Ituiutaba/Prata can be assigned to Abelisauridae, evidencing a continuous spatial distribution along the Bauru Group and those sites overlaying the Serra Geral formation in the southeastern state of Mato Grosso. Further studies at Ituiutaba, including information on the associated fauna, may subsidize the understanding of abelisaurid ecological requirements and the paleoenvironment of the Adamantina Formation.