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A review of the cuticular and sensory metatibial and metatarsal structures in cixiid planthoppers (Hemiptera: Fulgoromorpha) is proposed, depicting both their strong disparity and the great diversity of the patterns observed. Terminology and definitions for these structures are provided. The so-called lateral teeth of the metatibia in fact are particular styloconic sensory structures, called spiniform sensilla in Cixiidae. The apical metatibiotarsal teeth are non-sensory cuticular expansions, often bearing one or several chaetic sensilla ventrally, generally distributed in an internal and an external group of three teeth each, in some instances separated by a diastema; innermost and outermost teeth are generally larger. On the first tarsomere seven to eight teeth generally occur in one row, although two rows are observed in Brixidiini. A strong diversity of conformations and patterns is observed in the second metatarsomere. A specific subdorsal sensillum, of platellar type, may be present in the first metatarsomere teeth for a few taxa. It is generally present in the second metatarsomere, either as a narrow-based acutellar sensillum or as a broad-based platellar sensillum according to the taxon. Scanning electron microscope (SEM) analyses of 54 species of cixiids from all described tribes of the family, supplemented by data from the literature, are used to provide a metatibiotarsal diagnosis for each of the tribes of Cixiidae. In the state of our knowledge of the sufficiently precise observations of metatibiotarsal structures in the Cixiidae which are available, and of the phylogeny of the group as a frame of reference for their interpretations, we note that the observed patterns are probably the result of multiple and independent convergences and evolutionary regressions. These occurred at all levels of cixiid classification. Although these patterns can be useful in the identification of taxa at a low taxonomic level, they would be less useful for phylogenetic approaches. [ABSTRACT FROM AUTHOR]

The present in vitro study focuses on the filling ability of three different bioceramic cements with or without the addition of a bioceramic sealer in an open apex model on the marginal apical adaptation, tubule infiltrations, and void distributions as well as the interface between the cement and the sealer materials. To this end, sixty mandibular premolars were used. MTA-Biorep (BR), Biodentine (BD), and Well-Root Putty (WR) were used to obturate the open apex model with or without the addition of a bioceramic sealer, namely TotalFill® BC sealer™ (TF). A digital optical microscope and scanning electron microscope (SEM) were used to investigate the cement–dentin interface, marginal apical adaptation, and the material infiltration into the dentinal tubules. Micro-computed X-ray tomography and digital optical microscopy were used to investigate the cement–sealer interface. The results were analyzed by using the Kruskal–Wallis test. No significant difference was found between the groups for the marginal apical adaptation quality (p > 0.05). Good adaptation of the dentin–cement interface was found for all tested groups and the sealer was placed between the cement material and dentinal walls. All the groups demonstrated some infiltrations into the dentinal tubules at the coronal part except for the BR group. A good internal interface was found between the cement and the sealer with the presence of voids at the external interface. A larger number of voids were found in the case of the BD-TF group compared to each of the other two groups (p < 0.05). Within the limitations of the present in vitro study, all the groups demonstrated good marginal apical adaptation. The use of a sealer in an open apex does not guarantee good filling and, in addition, creates voids at the external interfaces with the dental walls when the premixed sealer is used with powder–liquid cement systems. The use of a premixed bioceramic cement could offer fewer complications than when a powder–liquid cement system is used. [ABSTRACT FROM AUTHOR]

Previous research has reported on hidden damage within the dentin introduced by cryopreservation, but the effect on the mechanical properties of the hard tissues at tooth level remains unclear. The main objective of this study is to investigate the effect of cryopreservation on the mechanical properties of teeth. A matched sample of 234 premolars of 117 children (9 ≤ age ≤ 16 years), bilaterally extracted for orthodontic reasons, were included. For each child, one tooth was randomly allocated to the cryopreservation group and the contralateral tooth was assigned to the control group. Static compression tests were performed to determine load to failure, stiffness, and toughness. In a subgroup of 20 teeth, a cyclic preloading or chewing simulation was performed. Additionally, the fracture mode was determined, and the microstructure of the fractured surfaces was examined using a scanning electron microscope (SEM). Linear mixed model analyses could not detect a statistical difference in the mean load to failure (p = 0.549), mean toughness (p = 0.968), or mean stiffness (p = 0.150) between cryopreserved and non-cryopreserved teeth. No significant difference in load to failure after cyclic preloading was detected between groups (p = 0.734). SEM analysis revealed comparable fracture characteristics between groups. It is concluded that cryopreservation does not affect the mean load to failure, stiffness, or toughness of teeth, indicating that hidden damage in the dentin is not critical at tooth level. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the feasibility of using the originally developed Laser Induced Breakdown Spectroscopy (LIBS) laboratory setup for the qualitative analysis of human tooth tissues and tooth restorations. Plasma was induced by the infrared TEA (Transversally Excited Atmospheric) CO2 laser in the air under atmospheric pressure. Optical emission spectra with sharp and well-resolved spectral lines and a negligibly low background were obtained. The results of the qualitative analysis showed the presence of various elements in the tooth tissues (P, Ca, and Mg), as well as trace elements within restorations such as Zn, Sn, Cu, Ag, and Hg. The estimated temperatures of plasma for composite, dentin, and amalgam were 21,000 K, 16,200 K, and 13,300 K respectively. The electron density deduced from the Stark-broadening line profiles varies from 8.5 × 1017 cm− 3 for amalgam, 2 × 1018 cm− 3 for composite, and 1.9 × 1018 cm− 3 for dentin. The surface of the tooth tissue was imaged with a scanning electron microscope (SEM), showing that dentin contains pores, cavities and bubbles. The results indicated that the alternative and cost-effective LIBS system can be used as a useful tool for further research on laser-induced plasma in dentistry. These insights are useful in the field of laser dentistry, where lasers are commonly utilized to treat teeth. [ABSTRACT FROM AUTHOR]

Aim: The purpose of this study was to assess and compare the effectiveness of three different irrigation activation systems in removing smear layer in single-rooted mandibular premolars using scanning electron microscope (SEM). Materials and Methods: Fifty-six extracted single-rooted mandibular premolars were included in the study (n = 56). The teeth were decoronated, working length was determined, and canals were prepared till #30/0.09, with 5.25% sodium hypochlorite and saline as working solution. Final irrigation was performed with 5 mL of 17% ethylenediaminetetraacetic acid solution using three different activation systems. Teeth were randomly divided into four groups: Group A (control group) - conventional syringe irrigation with 30-G single side-vented needle; Group B (passive ultrasonic irrigation [PUI] method) - PUI with #20 Irrisafe ultrasonic files activated for 1 min; Group C (sonic activation) - EndoActivator system using the yellow tip (#20/0.04) activated for 1 min; and Group D - Tornado Disinfection Kit using GF Brush for 20-30 s as per the manufacturer's instructions. The samples were sectioned and subjected to SEM at × 2500 magnification. The efficacy of smear layer removal was assessed and scored by two operators. The collected data were analyzed statistically using Chi-square test (P < 0.05). Results: There was no statistically significant difference observed between the three different activation groups and the control group (P < 0.05). Conclusion: PUI performed better than all the study groups in removing smear layer from coronal, middle, and apical third of root canals. EndoActivator and Tornado Disinfection Kit performed similar in coronal and middle third, but the efficacy in apical third was inferior to the PUI group. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to investigate the dentin bond strength of composite resins in response to environmental pressure changes. Methods: Ninety extracted human molar teeth were used. A mould (3 mm x 4 mm) was adapted on dentin, resin composites (conventional [n = 30] and single-shade composites [Ohmnicroma] [n = 30]) were filled in two increments of 2 mm. The bulk-fill composites (n = 30) were filled with one 4 mm increment. The specimens were stored for 30 days in artificial saliva. The specimens were exposed to hyperbaric pressure (283.6 kPa; 2.8 atmospheres absolute [atm abs]) or hypobaric pressure (34.4 kPa; 0.34 atm abs) once daily for 30 days and the control group was stored at atmospheric pressure for 30 days. The bond strength was tested with a universal testing machine and the failures were examined with a stereomicroscope and scanning electron microscope. Statistical analyses were performed using analysis of variance with post hoc tests, and the Weibull analysis. Results: Regardless of environmental pressure changes, the bulk-fill composites showed the highest bond strength. There was no significant difference in bond strength between the hypobaric and atmospheric pressure (control) groups after 30 days in all resins. The hyperbaric group showed lower bond strength for bulk-fill composites than the control group. Conclusions: Dentists experienced in diving and aviation medicine should definitely take part in the initial and periodic medical examinations of divers and aircrew to give appropriate treatment. Bulk-fill composite resins can be preferred in divers and aircrew due to high bond strength values. [ABSTRACT FROM AUTHOR]

Background: Recently, the caries management had shifted from extension for prevention to early detection and remineralization of remaining tooth structure using noninvasive techniques. Aim: The present trial was carried out to assess the effect of adding mono-n-Dodecyl phosphate as a surfactant to ceramic on remineralization of dentin. Materials and Methods: The 32 teeth were divided into the following four groups randomly (n = 8 each group) – Group I: cavities not restored, Group II: Restored with ceramic, Group III: restored with ceramic and 2% mono-n-Dodecyl phosphate, and Group IV: restored with ceramic and 5% mono-n-Dodecyl phosphate. Knoop indenter microhardness tests were done at 10, 20, and 40 days. The surface was evaluated under scanning electron microscope. The collected data were subjected to statistical evaluation, and the results were formulated. Results: In ceramic restored (Group II), an increase in Knoop microhardness (KHN) values was seen at 10-, 20-, and 40-day assessment with the respective values of 102.2 ± 20.3, 118.7 ± 19.4, and 127 ± 15.1. Similarly, a constant increase at different assessments was observed for Groups III and IV with 2% and 5% of mono-n-Dodecyl phosphate with ceramic with a 40-day KHN value of 128.2 ± 21.4 for Group III and 113.5 ± 17.3 for Group IV. A statistically significant difference was seen between ceramic and 5% mono-n-Dodecyl phosphate (Group IV) with hardness values of 30.31%, 29.8%, and 21.78% for Groups II, III, and IV, respectively, at 20 days. Conclusion: The present study concludes that ceramic restorations are effective in promoting dentin remineralization. However, the addition of only 2% mono-n-Dodecyl phosphate was beneficial, whereas 5% mono-n-Dodecyl phosphate reduced the efficacy of ceramic on dentin remineralization. [ABSTRACT FROM AUTHOR]

Background: The long-term success of root canal therapy depends on the effective debridement and removal of smear layer and debris from the canal. Root canals with difficult anatomy and complex systems pose great challenge to achieve this. Mechanical therapy alone cannot achieve this goal, various intracanal chemicals also have their own limitations along with the difficulty in reaching the farfetched and difficult areas, and hence, introduction of ultrasonic bypass system has been a boon for the endodontic therapy. Objectives: The aim of this study is to compare the various root canal medicaments along with ultrasonic bypass system in effectively cleaning the debris and smear layer from the various parts of the root canal system. Materials and Methods: Forty single-rooted anterior maxillary and mandibular human teeth were collected for this study, after disinfection, they were sectioned into three equal parts coronal, middle, and apical and these parts were later studies under SEM (Scanning Electron Microscope) and scoring as per the scoring criteria set before the study was done and results were then compared statistically. Results: Group with both ethylenediaminetetraacetic acid (EDTA) and NaOCl with ultrasonic bypass system was the most effective one, when compared with sterile water, NaOCl + ultrasonic bypass system, EDTA + ultrasonic bypass system. NaOCl + ultrasonic bypass system was more effective as compared with the EDTA + ultrasonic bypass system. Conclusion: Ultrasonic bypass system is a useful tool for debris and smear layer removal from a root canal system, but its effectiveness increases when both EDTA and NaOCl are used along with it. [ABSTRACT FROM AUTHOR]

Context: Cordless gingival retraction materials are now routinely used method for gingival retraction. Although evidence-based information is available on the effect of gingival displacement cord and cordless system on the effectiveness of displacement and the periodontal health, there is a lack of literature regarding the effect of cordless retraction agents on enamel and dentin substrates. Aim: The purpose of this investigation was to analyze the changes on the smear layer induced by the hemostatic agent and cordless retraction material at scanning electron microscopic level. Materials and Methods: Ferric sulfate (15.5% m/v), expasyl, and magic foam cord were evaluated. Buccal surfaces of 16 recently extracted mandibular premolars were prepared for metal-ceramic crowns, and four teeth each were exposed to ferric sulfate solution, expasyl, and magic foam cord, respectively, for 5 min. Teeth in the control group were exposed to distilled water. The assessment of changes was performed using a scanning electron microscope (SEM). Results: SEM exhibited smear layer covering the dentin and occluding the dentinal tubules in the control group. Exposure to ferric sulfate caused the opening of few of the dentinal tubules whereas expasyl caused the partial removal of smear layer with dentinal plugs partially occluding the openings of most of the dentinal tubules. The specimens treated with magic foam exhibited a smear layer similar to the control group. Conclusions: The smear layer was affected most with ferric sulfate solution, followed by expasyl and magic foam cord. Magic foam cord did not affect the smear layer. [ABSTRACT FROM AUTHOR]

Introduction: Dental caries has inflicted humankind from the very beginning and has encompassed every part of the globe, thus justifying the widespread of this pandemic disease. Caries removal conducted by conventional methods involves cavity preparation, which entails the use of high-speed rotary equipment, which has certain inherent drawbacks. To overcome these drawbacks, chemomechanical caries removal technique was developed, which involves softening of carious tissue by chemically altering it so that it can be mechanically removed using hand instruments. Objectives: The purpose of the present study was to evaluate and compare the efficacy of conventional and chemomechanical methods of caries removal in deciduous and permanent teeth. Methodology: Thirty freshly extracted human carious teeth were selected, cleaned, sectioned, and examined. The two halves of each deciduous and permanent tooth were divided into two groups according to the method of caries removal used, i.e., the mechanical method and chemomechanical method. In one Group, the carious lesion from one half of each tooth was removed mechanically with a slowspeed round bur, whereas other half of the same tooth were removed by chemo mechanical method. The preparation time for each caries removal technique for each sample was noted. Each sample was rinsed, dehydrated, mounted on stubs, and then evaluated using a scanning electron microscope and images were captured. The data were collected and given for statistical evaluation. Results: Awaited. [ABSTRACT FROM AUTHOR]

Scorpions are terrestrial arthropods inhabiting deserts. Exomorghological studies play an important role in the identification of different scorpions' species. The current study deals with the ecomorphology of four species of scorpions belong to the family buthidae (Leiurus quinquestriatus, Androctonus amoreuxi, Orthochirus innesi and Buthacus leptochelys) inhabiting New Valley governorate, Egypt. Random samples were implemented during the period from April to July, 2017 and July to September, 2019. Scorpions were obtained from the area under rocks, gap of soil, leaf litter, under bark, and within vegetation. Morphological characteristics of these species were done using a scanning electron microscope (SEM). In conclusion, the differences among four species of studied scorpions were noticed in the dorsal carapace, respiratory pores of the third segment of mesosoma, pectinal teeth count between females and males, last segment of metasoma and telson. In all scorpions' species studied, one venom pore was detected except in Androctonus amoreuxi two venom pores in telson were observed. [ABSTRACT FROM AUTHOR]

Background: Bovine and porcine teeth are often used in in vitro experiments as substitutes of human teeth. Objectives: The aim of the present study was to perform a comparative analysis of enamel morphology of permanent human, bovine and porcine teeth under the scanning electron microscope. Methods: As many as 10 human, 10 bovine, and 10 porcine teeth were studied. All the teeth were sectioned and the halves were randomly divided into 2 groups according to the examined tissue (vestibular enamel at the mid-height of the dental crown and in the cervical area). Human and bovine enamel was etched for 15 sec and porcine enamel for 30 sec. The scanning electron microscope analysis was performed. The length and width of enamel prisms were determined with the "Met-Ilo" 1.1 computer program. Results: All enamel samples revealed the same etching pattern--Silverstone's type 2. Bovine enamel showed a similar porosity and the amount of interprismatic enamel compared to human enamel while the amount and width of interprismatic enamel bands in porcine enamel were evidently greater. The shape of the porcine prisms was visually similar to human prisms, although dimensions were significantly different. However, bovine prisms differed in form and appeared to be distinctly elongated. Conclusions: Reported findings indicate that the results of experimental studies carried out on bovine and porcine enamel should not be compared with the results obtained on human enamel. [ABSTRACT FROM AUTHOR]

Purpose: To establish the fracture toughness (K1C) and flexural bond strength of commercially available denture teeth to heat cured, CAD/CAM and 3D printed denture‐based resins (DBRs). Materials and Methods: Three types of DBRs (Heat cure, CAD‐milled and 3D printed) and four different types of commercial denture teeth (Unfilled PMMA, double cross‐linked PMMA, PMMA with nanofillers and 3D printed resin teeth) were investigated. DBR and epoxy embedded denture teeth (n = 30 per group) specimen beams (25 × 4 × 3 mm) were fabricated. The testing ends of all the specimens were surface treated, bonded and processed according to manufacturer's instructions. Twenty specimens were thermal cycled to simulate the effects of 6 and 12 months intraorally. A 4‐point bend test, using the chevron‐notched beam method was done and K1C (MPa ·m1/2) and flexure bond strength (MPa) were calculated. All specimens were analysed for the mode of failure under the light microscope and selected specimens under scanning electron microscope. Results were statistically analysed using ANOVA (SPSS Ver 24). Results: The mean K1C was the highest for the teeth bonded to the heat‐cured DBR group (1.09 ± 0.24), followed by CAD/CAM (0.43 ± 0.05) and 3D printed groups (0.17 ± 0.01). Differences were statistically significant (p < 0.01). Within each group, aging showed statistically significantly lower values but no statistical significance between the mean K1C and flexural bond strength (p = 0.36). The dominant mode of failure was cohesive in the CAD/CAM groups and adhesive in the heat‐cured and 3D printed groups. Conclusion: Teeth bonded to heat‐cured DBRs produced the highest K1C.The bond strength decreased significantly with aging. Teeth bonded to CAD/CAM and 3D printed DBRs showed significantly lower bond strength, with no significant influence of aging. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study is to compare the microleakage of bulkfill composite activated by modulated photoactivation between fluorosed and nonfluorosed teeth using the confocal laser scanning microscope. Methodology: One hundred and twenty intact human premolar teeth with Thylstrup and Fejerskov index fluorosis index 0–4 were stored in 0.5% thymol at the room temperature until further use. Standardized Class V preparations of 2 mm depth, 3 mm width, and 2 mm height were prepared on the buccal surface. The cavities were etched with 37% phosphoric acid, rinsed and primed with Tetric N bond, cured for 20 s with Quartz Tungsten Halogen (QTH) variable intensity light-curing unit spectrum-800 operating at 450 mW/cm2. Later, bulk fill composite was placed in the cavity and cured. Depending on the curing mode used, all the fluorosed and nonfluorosed teeth were divided into three subgroups each (n = 20) – Conventional light curing, stepped curing, and pulse delayed curing. All samples were stored in distilled water at the room temperature for 24 h and subjected to 500 thermocycles. The prepared teeth were placed in 0.6% rhodamine solution for 48 h; sectioned longitudinally using a hard-tissue microtome and scanned under a confocal laser scanning electron microscope. Data were analyzed using the one-way ANNOVA, Wilcoxson signed-rank test, and Kruskal–Wallis test. Results: Significant differences were observed between fluorosed and nonfluorosed groups. Intragroup comparisons showed significant differences between fluorosed step and conventional subgroups. Conclusion: Fluorosed teeth had higher microleakage values than nonfluorosed teeth. Pulse-delayed subgroup had the least microleakage to that of conventional and stepped curing subgroups, in both fluorosed and nonfluorosed groups. [ABSTRACT FROM AUTHOR]

Purpose: To systematically review all studies comparing manual instrumentation with at least one rotary instrument in the preparation of the root canal of permanent human teeth. Methods: The electronic databases PubMed, EMBASE, LILACS, IBECS and BBO were searched. In vitro studies published until 27 of September, 2016 were included. For statistical analysis, we used the Comprehensive Meta-Analysis software (Biostat), considering P< 0.05 significant. Results: A total of 1,104 articles published until September 27, 2016 were obtained, with 57 meeting the eligibility criteria. The studies were grouped according to the main methodology used (computerized tomography, periapical radiography, image amplification and scanning electron microscope). Due to the wide variability of the methodologies and evaluated parameters, a subgroup analysis was performed based on the evaluated parameter. The metaanalysis revealed that rotary instruments caused a significant reduction in instrumentation time and a smaller change of the canal curvature than manual instruments. The rotary instrumentation presented better results regarding root canal transportation, ability of centralization within the canal path and shaping of the canal. Manual instrumentation performed better with regard to the smear layer and debris production, more instrumented canal surfaces and fewer dentin defects. [ABSTRACT FROM AUTHOR]

Introduction: Simplifying single-bottle adhesive technology to satisfy clinicians’ demand for adhesive procedures, particularly in terms of making the techniques faster, less technically sensitive, and more user friendly, has led to the development of multi-mode universal adhesives, which were designed to bind to tooth structures via the etch-and-rinse, the self-etch, and the selective-etch modes using a single bottle of adhesive solution. Objectives: The aim of this study was to determine the dentin bonding ability of multi-mode universal adhesive systems in relation to different etching modes and etching time periods using micro-shear bond strength analysis. Material and methods: Three multi-mode universal adhesives and one etch-and-rinse adhesive were assessed in this study. Micro-shear bond strengths (μSBS) to dentin were obtained in etch-and-rinse (etching 5 s/10 s/15 s) and self-etch modes. For each test condition, 10 specimens were prepared for each group. A scanning electron microscope (SEM) was used to examine representative bonded specimens, treated dentin surfaces, and the resin/dentin interface for each test condition. Results: Multi-mode universal adhesives showed the lowest μSBS results in etch-and-rinse mode for 10-s and 15-s etching (p < 0.05). Universal adhesives and self-etch adhesives showed similar μSBS values in self-etch mode (p > 0.05). Conclusions: Analysis concluded that phosphoric-acid etching for time periods greater than 5 s significantly reduced the efficacy of bonds when using multi-mode universal adhesives. [ABSTRACT FROM AUTHOR]

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The article presents an in vitro study of caries-like lesions created in occlusal fissures in recently erupted human premolar teeth by using polarized light microscopy. Extraction of the teeth was required for orthodontic purposes. After extraction, the teeth were separated from soft tissue, cleaned with a fluoride-free prophylaxis paste, and stored in distilled water. Caries-like lesions were created in the enamel by using gelatin gel acidified with the addition of lactic acid. The specimens were examined under a scanning electron microscope (SEM).

This article discusses a study which aimed to observe and measure the external and internal fit of Cerestore crowns on prepared models, as well as their cement film thickness after cementation. The study identified the marginal characteristics of cores and crowns by scanning electron microscope (SEM) observation. It fabricated all cores and crowns according to the Cerestore technical manual. It showed an excellent fit of the cores and crowns on the dies. The study also presented the cement film thickness measurements on the maxillary right central incisor.

The chelating and antimicrobial capacity of a novel modification of 17% EDTA with silver nanoparticles (AgNPs) (EDTA-AgNPs) was evaluated in-vitro for root canal treatment (RCT). The EDTA-AgNPs solution was characterized by UV-Vis spectroscopy, ζ-potential and high-resolution transmission electron microscopy (HRTEM). Antimicrobial capacity was evaluated against Candida albicans and Staphylococcus aureus in planktonic and biofilm cells by broth macrodilution (24 h) and XTT assays, (1, 10 and 30 min) respectively. The chelating capacity of EDTA-AgNPs was assessed indirectly (smear layer removal) and directly (demineralizing effect) in bovine dentin at two silver concentrations, 16 and 512 μg/ml at 1 and 10 minutes of exposure time. Smear layer removal was evaluated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The demineralizing effect was determined by atomic absorption spectroscopy (AAS), microhardness test (MH) and X-ray diffractometer (XRD). Synthesized AgNPs were quasi-spherical in shape with an average size of 13.09 ± 8.05 nm. 17% EDTA-AgNPs was effective to inhibit C. albicans and S. aureus in planktonic and biofilm cultures. The smear layer removal and demineralizing effect were similar between 17% EDTA-AgNPs and 17% EDTA treatments. The 17% EDTA-AgNPs solution proved to be an effective antimicrobial agent, and has a similar chelating capacity to 17% EDTA alone. These in-vitro studies strongly suggest that EDTA-AgNPs could be used for effective smear layer removal, having an antimicrobial effect at the same time during RCT. [ABSTRACT FROM AUTHOR]

Background:Dentine has been examined extensively for age-related physiological changes, but there are limited data on age-related changes at ultrastructural level of dentine. Aim:The present study aimed to examine age-related ultrastructural changes in calcospherites of human dentine under the scanning electron microscope. Materials and methods:Thirty single rooted teeth of North Western adult Indians (18–75 years) were collected from the Department of Oral Health Sciences, PGIMER, Chandigarh. Labiolingual sections were prepared and morphology of calcospherites was studied at different locations (coronal, cervical, midroot and apical) of the tooth. Results:Morphologically, four types (I [small, unfused and discrete], II [partially fused and globular], III [large, completely fused] and IV [structureless]) of calcospherites were seen in the sample. With advancing age, type I calcospherites approached neighbouring crystals and changed their form to type II, which ultimately coalesced and transformed to type III. Results revealed that among different age groups (young, middle and old), calcospherites of only type I, II and III showed statistically significant differences in their shapes using Pearson’s Chi-square test. Statistically non-significant differences were obtained in the shapes at different locations of the tooth. Conclusions:Results showed that calcospherites get fused as age advances. There is a change in the shape of calcospherites based on the location of the tooth. [ABSTRACT FROM PUBLISHER]

The article presents information about a replication technique that produces a three-dimensional model of tooth structures. This technique was used for examining structural changes in teeth with the help of scanning electron microscope (SEM). Polyether dental impression materials were used while employing this method. Single tooth impressions were obtained from teeth which had been etched with phosphoric acid solution for 2 minutes to produce an etched enamel surface. The tooth surfaces were moistened with water before the impression material was applied.

Introduction: In forensic context precise knowledge on physical and histological changes of teeth subjected to high temperatures is of great importance. Preserving fragile incinerated teeth for physical, histological and ultra structural examinations is essential in fire investigations involving the origin of fire, its cause as well as the identification of victims which relies on a thorough understanding of the structural changes in dental tissues subjected to heat. Aim: The study was conducted to evaluate the physical and ultrastructural changes seen in freshly extracted teeth when subjected to gradual heating at different temperatures using Scanning Electron Microscope (SEM). Settings and design: Freshly extracted teeth collected from subjects of different age groups were subjected to different temperatures using laboratory furnace and findings were correlated to the temperature. Materials and Methods: The study was conducted on 60 healthy freshly extracted teeth belonging to age group between 20-30 years. Group A comprised of control group which included teeth that were not subjected to heat whereas Group B, C and D comprised of teeth that were subjected to different temperatures i.e., 100°C, 300°C and 600°C respectively for a time of fifteen minutes in laboratory furnace, after which they were processed for SEM examination. Each group included 15 teeth; 5 anteriors, 5 premolars and 5 molars. results: Examination under SEM revealed definite ultra structural changes which were explicitly seen at particular temperatures (100°C, 300°C and 600°C). The samples showed cracks and charring of the tooth structure with ultra structural findings such as pebbles, granules, dots on enamel surface; and soap bubble pattern, honey comb pattern and snail track pattern on cementum surface. conclusion: Because of the consistency of morphological changes and the ultra structural patterns at various temperatures, evaluation of incinerated dental remains using SEM can provide additional investigative avenues in victim identification and in the areas of forensic fire investigations. [ABSTRACT FROM AUTHOR]

Longitudinal and cross sections of teeth from 17 species of the Recent dolphins (Delphinoidea and Inioidea) were examined under scanning electron microscope to study the arrangement and ultrastructure of dental tissues with reference to phylogenetic and functional constraints. For most species, enamel had a simple bi-layered structure of radial enamel and an outer layer of prismless enamel. The outer prismless layer varied from 5 to 30 % of enamel thickness. The enamel of Burmeister's porpoise ( Phocoena spinipinnis) was entirely prismless. The prisms had an open sheath; tubules and tuft-like structures were common at the enamel-dentine junction. Cetacean dentine was characterized by irregularly distributed dentinal tubules in a relatively homogenous dentinal matrix. Radial enamel was observed in all Delphinoidea and in the franciscana ( Pontoporia blainvillei), whereas the Amazon river dolphin ( Inia geoffrensis) had prisms organized in Hunter-Schreger bands. HSB in enamel are regarded as a device for resisting propagation of cracks. These may occur due to increased functional demands, possibly related to the hardness of the species diet. Simplification in tooth shape and reduced biomechanical demands plausibly explain the primitive radial organization among delphinoids and Pontoporia. The HSB structure in the Amazon river dolphin, similar to those of extinct archaeocetes, seems to have secondary functional implications. However, the distribution of HSB in more-basal odontocetes is too poorly known to judge whether the HSB of Inia are a retained plesiomorphic feature or convergence. [ABSTRACT FROM AUTHOR]

The article offers information on the new genus and species based on the recovered dental and osteological materials of the cricetid (Mammalia, Rodentia) from the late neogene of Mallorca. It mentions that bones were extracted from the fossiliferous breccia and consolidated with Paraloid B-67 and treated with acetic acid. It states that measurements were acquired from the scanning electron microscope (SEM) photographs taken at the Optical and Electronic Microscopy Service of the Universitat de les Illes Balears. Moreover, anterocone is composed of two cusps, connected through transverse anterior protolophule.

Objective: To evaluate the appearance of the hybrid layer of one total-etch and one self-etch bonding agent on human teeth with and without the application of 2% chlorhexidine after water storage. Materials and Methods: Twelve human maxillary teeth (molars and premolars) had two Class II cavities (MO-OD) prepared. Teeth were separated in two groups (n=6) to receive either Adper Single Bond 2 or Adper SE Plus (3M ESPE). In one cavity, the dentin donding agent was applied following manufacturer's instructions. On the adjacent cavity, 2% chlorhexidine was applied for 30 seconds before the application of the bonding agent. Teeth were sectioned mesiodistally with a slow-speed diamond disk and stored in water at 37°C for four months. The teeth were prepared for scanning electron microscope observation. The appearance of the hybrid layer was observed and measured by two variables: clear image of hybrid layer and presence of resin tags in tubules. Data were analyzed with a Kruskal-Wallis test calculated at a 0.05 significance level. Results: All groups treated with chlorhexidine had the clear presence of a hybrid layer, whereas only half the specimens without chlorhexidine had a clear hybrid layer. Chlorhexidine did not affect the presence of resin tags. Conclusions: The use of 2% chlorhexidine before the application of a dentin-bonding agent reduced the deterioration of the hybrid layer when exposed to water. [ABSTRACT FROM AUTHOR]

Objective: To study the effectiveness of a dentifrice containing polymethyl vinyl ether-maleic acid (PVM/MA) copolymer in a silica base in occluding dentin tubules for treatment of dentin sensitivity.Methods: Thirty-two human dentin discs were divided into two groups and brushed in the morning for 30s each to study the dentifrices with and without PVM/MA copolymer. Dentin tubule occlusion and dentin permeability were evaluated with a focus variation three dimensional vertical scanning microscope (IFM) and electrochemical impedance spectroscopy (EIS). After second brushing for 30s in the afternoon the dentin discs were immersed in saliva for 16 h and then subjected to erosion using orange juice for 10 min. The effects of saliva and orange juice on tubule occlusion used in the study of dentifrices were further evaluated with IFM.Results: On average 97.7% of the dentin tubules were occluded after brushing in the PVM/MA group, as compared to 13.3% in the control group (p<0.0001). EIS showed that the impedance of the dentin disc increased after treatment with PVM/MA but not in the control group (p<0.05). After 16 h of storage in saliva and 10 min of erosion by orange juice, 86% of the dentin tubules remained occluded in the PVM/MA treated dentifrice. The sizes of the tubule openings were increased after orange juice erosion in the control group but not in the PVM/MA group.Conclusion: Dentifrice containing PVM/MA copolymer in a silica base effectively occluded dentin tubules. The intra-tubular plugs were resistant to saliva and orange juice challenges. [ABSTRACT FROM AUTHOR]

Aim: Space gaining method is one of the long standing methods used in orthodontics that still preserves its currency. The space method applied as made from the approximal surfaces of teeth is among the alternative methods developed against other methods. In this study, it is aimed to evaluate the results of morphological changes formed by classical metal band stripes and air rotor stripping (ARS) over teeth between 1st and 3d months by checking Scanning Electron Microscope (SEM). Materials and Methods: 40 premolar teeth of 10 patients were applied stripping process using ARS and metal band stripes as a space method from mesial and distal surfaces. The mesial and distal surfaces of 40 premolar teeth were examined by extracting teeth in the 1st and 3rd months. Results: In terms of surface roughness statistically significant difference was found in the stripping process made by ARS and metal band stripes. (p<.05) However when it was evaluated according to the 1st and 3rd months no statistically significant difference was found. (p>.05) Conclusion: As a result of our research we were convinced that ARS system will be more beneficial in terms of patient comfort and hygiene motivation after the treatment. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of the short-term use of a dentifrice containing nano-sized carbonate apatite (n-CAP) on the occlusion of the dentinal tubules using a scanning electron microscope (SEM) and an image analyser in vitro. One hundred human dentine specimens were wet ground with a silicone carbide papers and etched with 6% citric acid for 1 min to allow complete opening of the dentinal tubule. Specimens showing complete opening tubules were used as the baseline. The specimens were divided randomly into five groups: G1: 0% n-CAP, G2: 5% n-CAP, G3: 10% n-CAP, G4: 20% n-CAP and G5: 10%strontium chloride (SrCl2). Five specimens from each group were brushed by applying 50, 100, 250 and 500 strokes, respectively. All the specimens were evaluated by a SEM (×3000), and the degree of occlusion of the dentinal tubules was quantified using an image analyser. The results were analysed by one-way anova and a Tukey’s test using the spss 12·0 statistical package program. The dentifrice containing 20% n-CAP for 50 strokes, which indicated 2-day use, showed the highest tubular occlusion than the other groups ( P < 0·05). Moreover, this group showed 79·5% and 77·4% less open tubular area than the baseline and 0% n-CAP group, respectively. The groups containing various concentrations of n-CAP showed significant differences in the SrCl2 group after tooth-brushing for 500 strokes, which indicated 17-day use. According to this examination of the short-term use of desensitizing dentifrices in vitro, the dentifrice containing 20% n-CAP was the most effective in occluding the dentinal tubules. [ABSTRACT FROM AUTHOR]

Abstract: Objective: The aim of this study was to investigate the influence of a fiber post on the fracture mechanics of zirconia crowns inserted over endodontically treated teeth with different extent of coronal damage. Methods: Endodontically treated human molars with three types of coronal damage received fiber posts before cementation of zirconia-veneered crowns. Controls received composite resin cores without fiber posts. The specimens were loaded to failure and fractographically examined using a scanning electron microscope (SEM). Results: Statistical analysis revealed that specimens with fiber posts demonstrated significantly higher failure loads and favorable fracture pattern compared to the controls. At fractographic analysis, specimens with fiber posts demonstrated delamination of the veneer ceramic from intact zirconia under structure. Meanwhile, the specimens that were restored without a fiber post demonstrated micro-cracking of the composite core build-up resulting in loss of the support under the zirconia crowns which was responsible for the initiation of radial crack and catastrophic damage. Conclusions: Within the limitation of this study, the insertion of fiber post improved the support under zirconia crowns which resulted in higher fracture loads and favorable failure type compared to composite core build-up. [Copyright &y& Elsevier]

This in vitro study observed and compared the resin and non-carious sclerotic dentin interfaces generated by three different adhesives and two different techniques, using a scanning electron microscope (SEM). Thirty-two human premolars, with buccal, non-carious cervical lesions, were used. The teeth were randomly divided into eight groups. Group 1: Sclerotic dentin was treated with Single Bond (3M). Group 2: After superficial sclerotic dentin was removed with a diamond bur (Diatech, Coltene), the dentin surfaces were treated with Single Bond. Group 3: Sclerotic dentin was treated with Clearfil SE Bond (Kuraray). Group 4: After superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond was applied. Group 5: Sclerotic dentin was treated with Xeno III (Dentsply). Group 6: After superficial sclerotic dentin was removed with a bur, Xeno III was applied to the dentin surfaces. For Groups 7 and 8, after the superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond, with an additional 37% phosphoric acid gel, was used on the sclerotic dentin surfaces in Group 7 and Xeno III was used in Group 8. In all groups, the cavities were restored with Filtek Supreme (3M). All the specimens were sectioned longitudinally and polished along the cut surface. The sections were treated with 37% orthophosphoric acid for five seconds, rinsed with water and treated with 5% NaOCL for 10 minutes. The specimens were then gold-sputter coated and evaluated under SEM. The thickness of the hybrid layer was measured on the gingival, occlusal and axial dentin interfaces. ANOVA was performed to determine whether there were any statistically significant differences in hybrid layer thickness. Post-hoc multiple comparisons were done with Tukey's test. Hybrid layer thickness was increased with all adhesives when superficial dentin was removed with a bur. Hybrid layer thickness showed significant differences between total-etch and self-etch systems. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to compare the surface roughness of nanofill (Filtek Supreme XT dentin shade and transparent shade, Filtek Z350, and Estelite Sigma), nanohybrid (Tetric EvoCeram, Ceram X, and Premise), and microhybrid resin composites (Filtek Z250, Tetric Ceram, and Clearfil AP-X) with the materials after polishing or brushing. Materials and Methods: Forty specimens of each resin composite were polymerized for 40 seconds under a matrix strip in cylindrical molds. Each type of polymer was divided into four subgroups: unpolished, polished with abrasive disks (Sof-Lex), polished with silicone-impregnated polishing devices (Astropol), and brushed with a toothbrush (Oral B) and toothpaste (Colgate). The surface roughness of each specimen was determined using a contact stylus profilometer and by observation under a scanning electron microscope. Results: No significant differences in surface roughness among the materials were found on unpolished surfaces. For the nanofill resin composites, there were no significant differences in surface roughness between the two polishing methods or among the unpolished surfaces. After brushing, the surfaces of all materials, except those made from Filtek Z350 and Filtek Supreme XT (dentin), had greater roughness than unpolished surfaces and surfaces polished with either abrasive disks or silicone devices. The scanning electron microscope studies revealed that the surface irregularities of the materials corresponded to the results obtained using the surface roughness tester. CLINICAL SIGNIFICANCE The use of nanofill resin composites made with nanoclusters demonstrated the smoothest surfaces after polishing and brushing. ( J Esthet Restor Dent 19:265–275, 2007) [ABSTRACT FROM AUTHOR]

Aim. To compare in vitro the cleanliness of root canal walls following the use of two automated instrumentation techniques. Methodology. Thirty extracted human maxillary central incisors, maxillary and mandibular canines and premolars with single root canals were examined in this study. The teeth were divided into two groups. In group 1 (20 teeth), automated canal preparation was performed using Anatomic Endodontic Technology (AET). In group 2 (10 teeth), root canals were prepared with ProTaper nickel titanium (NiTi) rotary instruments. Irrigation was performed using alternately 3.00% NaOCl and 18% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined using a scanning electron microscope. The presence of a debris and smear layer was recorded at the coronal, middle and apical thirds of root canals using a fourstep scoring scale. Mean scores for debris and smear layers were calculated and statistically analysed for significance (p < 0.05) between and within the groups, using the Mann--Whitney--Wilcoxon and Friedman nonparametric tests. Results. Under the conditions of this study, the removal of superficial debris and smear layers was generally good with both canal preparation techniques. However, both techniques resulted in variable presence of residual superficial debris and smear layers. Statistical analysis showed that there was no significant difference between the experimental groups in all thirds of root canals for a superficial debris and smear layer (p > 0.05). Comparison of the removal of the smear layer among the three regions showed that in AET group there was a statistically significant difference among all parts, especially between the middle and apical thirds (p < 0.005). Overall, the middle sections were cleaner than the coronal and apical ones. Conclusions. Complete cleanliness was not achieved by any of the techniques and instruments investigated. It may be inferred that the choice between AET and ProTaper instrumentation should be based on factors other than the amount of root canal debridement, which does not vary high significantly according to the instruments used. [ABSTRACT FROM AUTHOR]

The Environmental Scanning Electron Microscope (ESEM) equipped with a Gaseous Secondary Electron Detector (GSED) was used to image and analyze materials of different density, composition and structure applied in dentistry. Under ESEM conditions (at a H2O vapor pressure of 1-10 Torr) the hydrated surfaces of native teeth, which were coated with different polymers, generated a topographic and also a material specific contrast. The backscattered (BSE) and the secondary (SE) electrons involved into the imaging process produced a cascade-dependent mixed signal at the GSED. The material-specific contrast, generated by the BSE cascade, depends mainly on the atomic number z of the investigated material. The topographic contrast is based principally on the SE cascade. For the exact differentiation of the specific signal components inside of the ESEM, we additionally used a backscattered electron detector (BSED), the application of which allowed us to detect pure BSEs and no signals from cascade-dependent electrons. Conventional scanning electron microscopy (CSEM) used to investigate and image the structures of teeth and applied dental materials needs time-consuming and often artifact-inducing preparation steps before the partially hydrated specimen can be investigated, whereas the ESEM technology permits the imaging of hydrated organic structures with no prior specimen preparation. In the ESEM the interfaces between the hydrated organically structured tooth surfaces and the artificially applied polymer materials with its specific bond characteristics can be analyzed very fast and repeatedly (e.g. after etching series) at a reproducible high quality level. [ABSTRACT FROM AUTHOR]

Aim To compare the efficacy of ProFile rotary Nickel–Titanium (Ni–Ti) instruments and Hedstroem-files (H-files) combined with Gates-Glidden (GG) drills during removal of gutta-percha root fillings used in combination with one of the four representative sealers. Methodology Forty-eight single-rooted human teeth, with fully formed apices and straight root canals were used. The root canals were accessed and instrumented using a stepback technique with H-files. They were randomly assigned to four groups and subsequently filled with a combination of lateral and vertical condensation of gutta-percha and one of the following sealers: Roth 811, AH26, Endion and Roekoseal. The root fillings were removed 1 year later, using either H-files in combination with GG drills or the ProFile Ni–Ti system. Teeth were then grooved longitudinally and split. The amount of gutta-percha and sealer remaining on the root canal walls was traced and scored visually with the aid of a stereomicroscope. The scores were analysed and statistically compared with the Kruskal–Wallis test between the ProFile and H-file groups, as well as among the four sealer subgroups. Two samples from each group were studied under the scanning electron microscope to enhance inspection of canal walls and remaining material. Results Sealer remnants were observed with both techniques mainly in the middle and apical third of the root canal. The ProFile system and the H-files were associated with similar amounts of remaining filling material ( P > 0.05). In the cervical third of the root canal all sealer remnants were removed with both techniques. In the middle and apical third AH26 was associated with a statistically significant greater quantity of remnants on the root canal walls with both removal techniques ( P < 0.05). Endion, Roth 811 and Roekoseal were associated with approximately the same amount of filling material in the middle third of the root canal ( P > 0.05), whereas in the apical third Endion was associated with significantly more remnants of filling material than the other two sealers with either ProFile or H-files ( P < 0.05). Conclusions None of the methods used for the removal of root fillings was totally effective, especially in the apical third of the root canal. [ABSTRACT FROM AUTHOR]

Zmener O, Pameijer CH, Banegas G.Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic study.International Endodontic Journal,38, 356–363, 2005.To comparein vitrothe cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation.Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at×200 and×400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 μm square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal–Wallis nonparametricanovaand Dunn's tests.At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups.Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated. [ABSTRACT FROM AUTHOR]

We describe dental microwear in baboons (Papio hamadryas sensu lato) from the anubis-hamadryas hybrid zone of Awash National Park, Ethiopia, outline its variation with sex and age, and attempt to relate the observed microwear pattern to environment and diet. Casts of the maxillary second molar of 52 adult and subadult individuals of both sexes were examined with a scanning electron microscope at ×500. Digitized micrographs were taken at a consistent location on facet 9, and microwear was recorded with an image analysis software package. Univariate and multivariate statistics were used to investigate the shape, size, and density of microwear features. The overall pattern of microwear exhibits an unusual combination of high feature density, with numerous small pits and relatively wide striations, and a high correlation between width of pits and striations across individuals. We interpret this pattern as predominantly the consequence of abrasion by relatively small-caliber environmental grit when accidentally ingested with tough foods such as dried seeds and fruits, as expected in a terrestrial omnivore living in a dusty habitat. Statistical analysis revealed no significant differences between groups defined by sex, age, or troop membership, a result consistent with qualitative observations of feeding habits in this population, and which lends no support to the hypothesis that the longer jaws of adult males should result in longer striations. A trend towards greater feature density in females, however, might be due to limited sexual dinichism, and merits further investigation. [ABSTRACT FROM AUTHOR]

Isolated enamel defects are commonly seen in first permanent molar teeth but there has been little work on the physical and morphological composition of affected molars. The aim of this study was to determine the mechanical and morphological properties of hypomineralised first permanent molar teeth, utilising the Ultra-Micro-Indentation System (UMIS) and scanning electron microscope, respectively. Further investigations using Energy Dispersive X-ray Spectrometery (EDS), Back Scatter Electron (BSE) Imaging, and X-ray diffraction were employed to attempt to determine the chemical composition, mineral content and crystalline structure of the hypomineralised tissue, respectively, of eight first permanent molars with severe enamel hypomineralisation. The hardness and modulus of elasticity were found to be statistically significantly lower (0.53±0.31 and 14.49±7.56 GPa, respectively) than normal enamel (3.66±0.75 and 75.57±9.98 GPa, respectively). Although the fractured surface of the hypomineralised enamel was significantly more disorganised and the relative mineral content was reduced by approximately 5% in comparison to sound enamel, the mineral phase and Ca/P ratio was similar in hypomineralised and sound enamel. The dramatic reduction in the mechanical properties of first permanent molar teeth has ramifications when clinicians are choosing restorative materials to restore the defects. The reason for the dramatic reduction in mechanical properties of hypomineralised first permanent molar teeth is at present unknown. [Copyright &y& Elsevier]

It was the aim of this study to investigate the scanning electron microscopy (SEM) features and the element content of calcium (Ca) phosphorus (P), magnesium (Mg), oxygen (O), and carbon (C) of sound dentin, demineralized dentin, secondary dentin, intratubular and peritubular de novo dentin formation due to caries progression and to compare the element content with chemically pure hydroxyapatite. Eighteen extracted teeth with deep dentin carious lesions were embedded in Technovit 9100 (Kulzer), and serial sections of 80 microm thickness were made. These sections were then investigated with polarized light microscopy to identify the lesions. Two sections of each lesion were then coated with carbon and studied with a scanning electron microscope. Of the 18 teeth, 8 showed intratubular dentin formation. The element content was measured using energy dispersive X-ray analysis (EDX). About 75% of all involved dentin tubules showed intratubular de novo dentin formation. The Ca/P ratio in sound dentin, demineralized dentin, peritubular dentin, and secondary dentin was within the range of hydroxyapatite, whereas in intratubular dentin the Ca/P ratio was different than that of hydroxyapatite. The element content for Ca was statistically highly significantly different (P < 0.01) among sound dentin/intratubular dentin, sound dentin/peritubular dentin, and sound dentin/ secondary dentin, but not between sound dentin/ demineralized dentin and sound dentin/hydroxyapatite. For the other measured elements varying statistical differences were found. Our results indicate that intratubular dentin does not occlude the dentin tubules completely and mineralizes different than that of sound dentin and may therefore not be true hydroxyapatite. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to determine the influence of remineralisation time on rehardening of surface-softened enamel after citric acid erosion. Seven groups of 13 samples of human enamel were eroded in 0.3% citric acid at pH 3.2 for 2 h followed by profilometric measurements. Individual groups of specimens were placed in artificial saliva for 1, 2, 4, 6, 9 or 24 h. A control group was placed in isotonic saline for 24 h. After new profilometric measurements samples were ultrasonicated stepwise up to 480 s with profilometric measurements performed at 5, 30, 120, 240 and 480 s to measure the depth of surface softening. The control group had a softened surface layer of mean thickness 2.9 μm. Mineral deposition was seen at all remineralisation times by scanning electron microscopy. Exposure to artificial saliva for 1, 2 or 4 h produced a partial rehardening of the softened enamel; the additional surface losses produced by ultrasonication were lower and time delayed compared to the control group. Specimens remineralised for 6, 9 and 24 h showed little evidence of surface loss after ultrasonication. The data suggest that a complete rehardening of the softened enamel in vitro is reached after a remineralisation time of 6 h. These data are of clinical relevance to tooth wear. However, there is a need for studies in situ of enamel demineralisation and remineralisation. [ABSTRACT FROM AUTHOR]

The study assessed the bonding performance of three universal adhesives on desensitized dentin with etch-and-rinse mode or self-etch mode after nano-hydroxyapatite (nHAp)-based desensitizers application. Simulated sensitive dentin specimens were prepared and separated into four groups: no treatment as the negative control, groups desensitized by Biorepair toothpaste, Dontodent toothpaste, or nHAp paste. Three universal adhesives of All-Bond Universal, Single Bond Universal, and Clearfil Universal Bond with etch-and-rinse or self-etch mode were bonded to the desensitized dentin specimens separately, followed by resin composite build-ups. Micro-tensile bond strength was measured using a micro-tensile tester. The wettability of desensitized dentin was evaluated by the contact angle of the adhesives. Resin infiltration was observed by confocal laser scanning microscopy. Dentin tubular occlusion and nanoleakage were observed by scanning electron microscope. The results showed that the etch-and-rinse or self-etch mode of each adhesive showed similar bond strength when bonding to nHAp-based desensitized dentin. The dentin surface was partially covered by desensitizers after desensitization. Compared with the self-etch mode, stronger demineralization and more reopened dentin tubules were observed in the etch-and-rinse mode after acid etching; longer resin tags and more nanoleakage in the resin–dentin interface were observed when using the etch-and-rinse mode. When bonding to nHAp-based desensitized dentin with universal adhesives, no significant difference in bond strength was found between self-etch mode or etch-and-rinse mode; while the latter produced more nanoleakage in the resin–dentin interfaces. [ABSTRACT FROM AUTHOR]

(1) Background: This study aimed to evaluate the microporosity of the tooth surface structure adjacent to the cemento-enamel junction (CEJ) after the removal of composite fillings with a drill in comparison with removal by an Er:YAG laser and after cleaning with a periodontal curette, chemical EDTA and NaOCl (sodium hypochlorite) conditioning. (2) Methods: The research material consisted of 30 extracted premolars with cervical composite fillings. The teeth were divided into six groups according to the method of tooth preparation: group G1 (n = 5)—a diamond drill; group G2 (n = 5)—a diamond drill + curette; group G3 (n = 5)—a diamond drill + 24% EDTA (PrefGel, Straumann, Switzerland); group G4 (n = 5)—an Er:YAG laser (LightWalker, Fotona, Ljubljana, Slovenia) set with the following parameters: power: 1.65 W (composite removal, CR), 1.2 (tooth conditioning, TC), energy: 110 mJ (CR), 80 mJ (TC), frequency: 15 Hz, pulse duration: 50 μs, tip diameter: 1 mm, air/fluid cooling: 4, distance 1.5 mm, energy density: 14.01 J/cm2 (CR), 10.19 J/cm2 (TC); group G5 (n = 5)—an Er:YAG laser + 2% sodium hypochlorite (NaOCl); group G6 (n = 5)—an Er:YAG laser + 5.25% NaOCl. In each tooth, three cavities were made and subjected to analysis. The dentin surface was evaluated using a scanning electron microscope (SEM). (3) Results: Groups G1 and G2 exhibited mechanical damage to the tooth surface structure caused by the rotary motion of a diamond drill. The SEM image showed a smear layer that could only be removed chemically using 24% EDTA gel (group G3). The tooth surfaces prepared with the Er:YAG laser (groups G4–G6) revealed a homogeneous structure without damage along with open dentinal tubules (without smear layer) and visible denaturation of collagen fibers. The sodium hypochlorite (NaOCl) conditioning did not increase the visibility of dentinal tubules. (4) Conclusions: Dentin surfaces have open dentinal tubules after removal of the composite filling using the Er:YAG laser and therefore do not require additional NaOCl conditioning. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the wear failure changes of spindle hook teeth and the reasons for such failure during field work. Spindle samples were obtained from a fixed position of the spindle bar under different field picking area conditions and combined with the spatial distribution characteristics of cotton bolls in Xinjiang. After cutting a spindle sample, a scanning electron microscope and an energy spectrum analyzer were used to characterize the micromorphology and element composition of the hook tooth surface and cross section under different working area conditions. The wear parameters of the hook teeth were then extracted. The results showed that the thickness of the coating on the surface of the hook tooth used in this study was between 66.1 µm and 74.4 µm. The major chemical element was chromium, with a small amount of nickel. During the field picking process, failure of the coating on the surface of the hook teeth initially appeared on the tooth tip and tooth edge, and then spread to the entire hook tooth surface. The wear failure of the hook teeth resulted from abrasive wear, oxidative wear, and fatigue peeling. As the picking area increased, the wear area of the hook teeth increased exponentially, while the wear width increased linearly. When the field picking area reached 533.33 ha, the maximum change rate of the wear area was 2.33 × 103 µm2/ha, and the wear width was 1.84 µm/ha. During field work, the thickness of the coating decreased from the cutting surface to the tooth edge, and the wear rate gradually increased. The wear rate at Position 1 was the slowest, at 0.01 µm/ha, and the wear rate at Position 5 was the fastest, at 0.25 µm/ha. [ABSTRACT FROM AUTHOR]

The purposes of the study were to observe the morphological changes on root canal walls after instrumentation and irrigation, and assess the efficacy of conventional cleansing procedures and the effectiveness of Er:YAG laser in removing debris and smear layer from the root canal walls. Thirty-six endodontically treated human mandibular incisor teeth with single root canals were bisected longitudinally and divided into three groups of 12 teeth. Group 1 (G1) was left unlased as a control. The teeth of group 2 (G2) and group 3 (G3) were irradiated by Er:YAG laser (laser parameters were set at 1 W, 100MJ/pulse and 10 Hz for 3s and 5s. The teeth were prepared for scanning electron microscope study. Control specimens showed debris and heavy smear layer obscuring the dentinal tubules at all levels in the canals. The root canal walls irradiated by Er:YAG laser were free of debris, with an evaporated smear layer and open dentinal tubules. These results suggested that Er:YAG laser irradiation had an efficient cleaning effect on the prepared root canal walls. [ABSTRACT FROM AUTHOR]

In order to obtain a replica technique suitable for a complete or segments of a dental arch two different impression materials were combined with two epoxy resin model materials. The models were examined and photographed in an optical microscope and a scanning electron microscope. No systematic differences were found between the used combinations of materials except a tendency towards greater contraction of one of the model materials. The A-silicone impression materials combined with one of the epoxy resin material seemed to be the easiest to handle and to give the best models. [ABSTRACT FROM AUTHOR]

A method involving carefully planned sectioning and grinding of human maxillary first premolars, allowing enamel structure to be studied with the SEM in more than one plane at the same time, was employed to demonstrate the extent of Retzius lines within the confines of' the three-dimensional enamel cap. It was found that the Retzius lines behaved as could be predicted by the theory stating that the striae represent one-dimensional cuts of two-dimensional, curved growth planes. Reizius lines in adjoining planes were continuous across the edge where the two planes met. In a supernumerary tooth, the surface of its hypoplastic tooth tip was continuous with distinct Retzius lines. The present observations provide for the first time direct morphologic verification of the supposed nature of Retzius lines, with reference to extent and continuity in three-dimensional space. [ABSTRACT FROM AUTHOR]

The dissolving effects of seven endodontic solutions on unprepared root canal walls of young intact human premolars were evaluated with the scanning electron microscope. After incubation at 37°C in distilled water or isotonic saline for 10 min the predentinal surfaces showed no changes as compared with untreated controls, The demineralizers Decal® and Largal Ultra® had little effect on the organic tissues but caused some decalcification where mineralized dentin was exposed. Nelex® caused concentration-dependent coagulation of the residual pulp tissue, making typical ring structures on the surfaces. Sodium hypochlorite at 2.5% and 5.0% dissolved most of the predentin, exposing the globular appearance of the mineralizing front. Salvizol® produced small globules on otherwise intact surfaces. Dissolution of both the organic and inorganic tissue of the root canal wall would require the combined use of two of the solutions studied. [ABSTRACT FROM AUTHOR]

The inner surfaces of 40 Concise® restorations placed in vivo on permanent molars have been studied by scanning electron microscopy. Only grinding traces could be seen on fillings from cavities which had not been etched, while the morphologic structure of the enamel and dentin was reflected on fillings from acid-etched cavities. Application of low-viscous non-composite resin in the cavities before filling with the composite resin did not influence the enamel pattern on the fillings, while the amount of processes of resin corresponding to the dentinal tubules in etched cavities was significantly increased. In the discussion the difference in surface structure of the filling is correlated to marginal leakage along similar restorations. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to study by means of scanning electron (SEM) and optical microscopy the adaptation of the low-viscous non-composite Nuva-Seal® and of the three high-viscous composite restorative materials Adaptic®, Compocap® and Concise® to phosphoric acid etched enamel surfaces from symmetric areas of pairs of contralateral human permanent anterior teeth. The SEM study demonstrated that the two types of material equally well reproduce the details of the enamel surface; the light microscopic observations showed that the length and shape of resin tags in the enamel surface are independent of the materials examined. The observations seem to allow the conclusion that bonding of composite restorative resins to phosphoric acid etched enamel surfaces is not conditioned by the employment of an intermediate film of a low-viscous non-composite resin.