Morphological, chemical and structural characterisation of deciduous enamel: SEM, EDS, XRD, FTIR and XPS analysis.

AIM: The purpose of this study was to characterise the enamel surface of sound deciduous teeth in terms of morphology, chemical composition, structure and crystalline phases. MATERIALS AND METHODS: The enamel of 30 human deciduous teeth was examined by: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Chemical differences between incisors and canines were statistically evaluated using the Mann-Whitney U test (p ≤ 0.05). RESULTS: Three enamel patterns were observed by SEM: 'mostly smooth with some groves', 'abundant microporosities' and 'exposed prisms'. The average Ca/P molar ratios were 1.37 and 1.03 by EDS and XPS, respectively. The crystallite size determined by XRD was 210.82 ± 16.78 Å. The mean ratio between Ca bonded to phosphate and Ca bonded to hydroxyl was approximately 10:1. CONCLUSION: The enamel of sound deciduous teeth showed two main patterns: 'mostly smooth with some groves' and 'abundant microporosities'. 'Exposed prisms' was a secondary pattern. There were slight variations among the Ca/P molar ratios found by EDS and XPS, suggesting differences in the mineral content from the enamel surface to the interior. The crystalline phases found in enamel were hydroxyapatite and carbonate apatite, with major type B than type A carbonate incorporation.

Effect of final irrigation protocols on microhardness and erosion of root canal dentin.

The aim of this study was to evaluate the effect of final irrigation protocols (17% EDTA, BioPure MTAD, SmearClear, and QMiX) on microhardness and erosion of root canal dentin. Fifty roots were sectioned transversely at the cement-enamel junction and each root was sectioned horizontally into 4-mm-thick slices. The samples were divided into five groups (n = 10) according to the final irrigation protocol: G1: distilled water (control group); G2: 17% EDTA; G3: BioPure MTAD; G4: SmearClear; and G5: QMiX. The dentin microhardness was then measured with a load of 25 g for 10 s. Initially, the reference microhardness values were obtained for the samples without any etching. The same samples were then submitted to the final irrigation protocols. A new measure was realized and the difference between before and after the procedures was the dentin microhardness reduction. In sequence, the specimens were submitted to SEM analysis to verify the dentinal erosion. The Kruskal Wallis and Dunn tests (α = 5%) were used to compare the results. The dentin microhardness decreased for all final irrigation protocols. There was no significant difference between groups 2, 3, 4, and 5 (P > 0.05), but this groups presented significant dentin microhardness reduction than G1 (P < 0.05). In G2, occurred the highest incidence of dentinal erosion (P < 0.05). 17% EDTA, BioPure MTAD, SmearClear, and QMiX promoted significant dentin microhardness reduction. Dentinal tubules erosion was promoted by 17% EDTA.

Effect of ammonium hexafluorosilicate application for arresting caries treatment on demineralized primary tooth enamel.

Ammonium hexafluorosilicate (AHF) has been applied to arrest caries without discoloration. The purpose of this study was to observe structural and elemental changes of demineralized and AHF applied primary tooth enamel. Enamel from the labial surface of 20 primary canines was divided into an unground side and ground side at the center of the tooth, and demineralized with 35% phosphoric acid for 6 min. The teeth were divided into 4 groups according to a 3-min application of AHF and 1 week of soaking in artificial saliva, as follows: group A (neither AHF nor saliva), group B (only saliva), group C (only AHF), and group D (AHF and saliva), and then subdivided according to whether the enamel was ground or unground. Specimens were analyzed with scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The data were statistically analyzed using ANOVA and Fisher's PLSD test at α = 0.05. In groups A and B, prism structures were seen, however, in groups C and D, enamel surfaces were covered with spherical particles. Ca/P ratio was significantly higher in groups C and D than in groups A and B. There was no significant difference between ground and unground enamel in the content of any element. The values for F, Na, Mg and Si persents and Ca/P ratio were significantly higher for the enamel surface than for points 10-30 µm beneath the surface. Results of this study suggest the possibility that AHF treatment arrests caries, although further study will be required to confirm this result.

Self-adjusting file cleaning-shaping-irrigation system improves root-filling bond strength.

INTRODUCTION: The aim of the present study was to assess the bond strength of root fillings in oval-shaped canals prepared with the self-adjusting file (SAF) system. METHODS: A careful specimen selection resulted in 2 equal groups, each consisting of 12 extracted mandibular canines with oval canals that had vital pulps before extraction. One group was subjected to the SAF protocol, and the other group underwent conventional protocol, which was the ProTaper system with syringe-needle irrigation. Full-strength sodium hypochlorite was used as an irrigant for both groups. The teeth were obturated in a standardized way, filled with a lentulo spiral as the root filling, and then prepared for micropush-out assessment by using root slices of 1-mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min(-1). The Student's t test for pairwise comparisons was applied to assess the effect of each preparation technique on the push-out bond strength. RESULTS: All specimens showed measurable adhesive properties to root dentin. In addition, no premature failure occurred. The group-by-location interaction was significant (P = .0071); thus, the group comparisons were dependent on the canal third. Overall, the push-out bond strength was the highest in the coronal third and the lowest in the apical third. SAF-prepared specimens displayed significantly higher bond strengths (P = .0012, 0.51-5.9 MPa). CONCLUSIONS: The present study showed that SAF preparation markedly influenced root-filling push-out bond strength in oval-shaped canals. Further investigations are needed to provide a better understanding of the physicochemical modifications of the root dentin prepared with the SAF cleaning-shaping-irrigation system.

Time-dependent effects of chitosan on dentin structures.

Complete debridement with smear layer removal are essential measures for achieving a successful outcome of root canal treatment. The aim of this study was to evaluate the effects of chitosan at different concentrations on the removal of the smear layer and on dentin structure after 3 and 5 min of application. Twelve recently extracted maxillary canine teeth were instrumented using the crown-down technique and irrigated with 1% sodium hypochlorite. The specimens were distributed according to the time and concentration of the final irrigating solution: G1: 0.1% chitosan for 3 min; G2: 0.2% chitosan for 3 min; G3: 0.37% chitosan for 3 min; G4: 0.1% chitosan for 5 min; G5: 0.2% chitosan for 5 min; G6: 0.37% chitosan for 5 min. All samples were prepared for SEM analysis. G1 exhibited removal of the smear layer, but not the smear plugs. G2 showed visible and open tubules with slight erosion of the peritubular dentin. Cleaning in G3 was similar to that in G2, however, the erosive effect was greater. There was expansion of the diameter of the tubules in G4; and in G5 and G6, there was severe erosion with deterioration of dentin surface. In conclusion, 0.2% chitosan for 3 min appeared to be efficient for removing the smear layer, causing little erosion of dentin.

Carisolv as an endodontic irrigant in deciduous teeth: an SEM study.

AIM: Root canal irrigation plays an important role in the debridement and disinfection of the root canal system. "The purpose of this study was to evaluate the efficacy of Carisolv , 1% sodium hypochlorite (NaOCl) gel, and 1% NaOCl solution as root canal irrigants in deciduous anterior teeth." MATERIALS AND METHODS: THIRTY-six extracted deciduous anterior teeth were used. Root canals were flooded with NaOCl solution in Group A, NaOCl gel in Group B and Carisolv in Group C and incubated for 30 min. Scanning electron microscope photomicrographs of canal wall debris in the apical, middle and coronal thirds were scored. RESULTS: The results showed that regardless of irrigation regime, canals were consistently cleaner in the coronal and middle thirds than in the apical thirds. NaOCl solution, NaOCl gel, and Carisolv had comparable activity at coronal third and middle third of root canals. At the apical third, NaOCl solution cleaned canals better than NaOCl gel and Carisolv. Carisolv cleaned debris better than NaOCl gel at the apical third. CONCLUSION: Carisolv can be used as an adjunct to root canal preparation.

Time-dependent effects of chitosan on dentin structures

Complete debridement with smear layer removal are essential measures for achieving a successful outcome of root canal treatment. The aim of this study was to evaluate the effects of chitosan at different concentrations on the removal of the smear layer and on dentin structure after 3 and 5 min of application. Twelve recently extracted maxillary canine teeth were instrumented using the crown-down technique and irrigated with 1% sodium hypochlorite. The specimens were distributed according to the time and concentration of the final irrigating solution: G1: 0.1% chitosan for 3 min; G2: 0.2% chitosan for 3 min; G3: 0.37% chitosan for 3 min; G4: 0.1% chitosan for 5 min; G5: 0.2% chitosan for 5 min; G6: 0.37% chitosan for 5 min. All samples were prepared for SEM analysis. G1 exhibited removal of the smear layer, but not the smear plugs. G2 showed visible and open tubules with slight erosion of the peritubular dentin. Cleaning in G3 was similar to that in G2, however, the erosive effect was greater. There was expansion of the diameter of the tubules in G4; and in G5 and G6, there was severe erosion with deterioration of dentin surface. In conclusion, 0.2% chitosan for 3 min appeared to be efficient for removing the smear layer, causing little erosion of dentin.

Completo debridamento dos canais radiculares com a remoção da smear layer são medidas essenciais no sucesso do tratamento endodôntico. O objetivo deste estudo foi avaliar os efeitos da quitosana, em diferentes concentrações, na remoção da smear layer e na estrutura da dentina, após 3 e 5 min de aplicação. Doze dentes caninos superiores, recém extraídos, foram instrumentados pela técnica crown-down e irrigados com hipoclorito de sódio 1%. Os espécimes foram distribuídos em seis grupos conforme o tempo e a concentração da solução irrigante final: G1: quitosana 0,1% por 3 min; G2: quitosana 0,2% por 3 min; G3: quitosana 0,37% por 3 min; G4: quitosana 0,1% por 5 min; G5: quitosana 0,2% por 5 min; G6: quitosana 0,37% por 5 min. Todas as amostras foram preparadas para avaliação em MEV. Os resultados mostraram que o G1 apresentou remoção da smear layer, mas não da smear plug. O G2 mostrou túbulos visíveis e abertos com ligeira erosão da dentina peritubular. A limpeza no G3 foi semelhante à do G2, no entanto, o efeito erosivo foi maior. No G4 houve ampliação do diâmetro dos túbulos e no G5 e G6, severa erosão com deterioração da superfície dentinária. Concluiu-se que a quitosana 0,2% por 3 min foi eficiente na remoção da smear layer, ocasionando pequena erosão.

Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation.

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

Este estudo avaliou o efeito do laser de diodo 980 nm na microinfiltração apical e na morfologia intrarradicular da dentina. Raízes de 110 incisivos inferiores foram utilizadas no estudo: 92 para o teste de microinfiltração e 18 para microscopia eletrônica de varredura (MEV). As raízes foram divididas em 3 grupos de acordo com a solução irrigante (água, NaOCl e NaOCl/EDTA) e subdivididas em 3 de acordo com a irradiação laser (sem irradiação, irradiados com 1,5 W e irradiados com 3,0 W). Duas amostras de cada subgrupo foram preparadas para MEV. As raízes restantes foram preenchidas com AH Plus e guta percha. A infiltração apical foi avaliada nas raízes por meio da penetração do corante e os dados foram analisados por ANOVA e teste de Tukey-Krammer (α=0,05). Os resultados da MEV mostraram intensificação das mudanças quando se aumentou a potência do laser e variações de acordo com a solução irrigadora. Camada de smear modificada foi observada em espécimes tratados com água e irradiados com laser. Raízes irrigadas com NaOCl/EDTA tiveram níveis menores de infiltração (0,17 ± 0,18 mm) estatisticamente diferente (p<0,05) das raízes irrigadas com água (0,34 ± 0,30 mm), mas semelhante (p>0,05) aos irrigados com NaOCl (0,28 ± 0,29 mm). As raízes não irradiadas tiveram níveis menores de infiltração (0,10 ± 0,14 mm), diferente (p<0,05) de 1,5 W (0,32 ± 0,22 mm) e 3.0 W (0,37 ± 0,32 mm). O laser de diodo 980 nm alterou a morfologia da dentina e aumentou a infiltração marginal apical.

Comparative SEM evaluation of three solvents used in endodontic retreatment: an ex vivo study.

This study compared, by scanning electron microscopy (SEM), the efficacy of three solvents on the removal of filling materials from dentinal tubules during endodontic retreatment. Forty human maxillary canines with straight canals were prepared according to a crown-down technique and enlarged to a#30 apical file size, before obturation with gutta-percha and a zinc-oxide-eugenol based sealer. The samples were stored for 3 months before being randomly assigned to four groups: chloroform (n=10), orange oil (n=10), eucalyptol (n=10) and control (n=10). Solvents were applied to a reservoir created on the coronal root third using Gates Glidden drills. The total time for retreatment using the solvents was 5 minutes per tooth. Following retreatment the roots were split longitudinally for SEM evaluation. SEM images were digitized, analyzed using Image ProPlus 4.5 software, and the number of dentinal tubules free of filling material from the middle and apical thirds was recorded. No significant difference was found among the solvent groups regarding the number of dentinal tubules free of root filling remnants in the middle and apical root thirds (p>0.05). However, the control group had fewer dentinal tubules free of filling material (p<0.05). Under the tested conditions, it may be concluded that there was no significant difference among the solvents used to obtain dentinal tubules free of filling material remnants.

Non-masticatory uses of anterior teeth of Sima de los Huesos individuals (Sierra de Atapuerca, Spain).

In this study we examine the labial and occlusal surfaces of incisors and canines of hominins recovered from the Sima de los Huesos (SH), middle Pleistocene site, in order to establish the possible extra-masticatory use of anterior teeth. We have compared the microwear of these fossils with microwear from the anterior teeth of Australian Aborigines, a population characterized by ethnographic evidence of the use of their teeth as a third hand. These two samples of teeth were microscopically analyzed using Scanning Electron Microscopy (SEM). Our results support the "cultural" origin of microwear observed on fossil teeth: we conclude that the SH hominins used their anterior teeth as a "third hand" for para- or extra-masticatory activities.

Comparative sem evaluation by of three solvents used in endodontic retreatment: an ex vivo study

This study compared, by scanning electron microscopy (SEM), the efficacy of three solvents on the removal of filling materials from dentinal tubules during endodontic retreatment. Forty human maxillary canines with straight canals were prepared according to a crown-down technique and enlarged to a#30 apical file size, before obturation with gutta-percha and a zinc-oxide-eugenol based sealer. The samples were stored for 3 months before being randomly assigned to four groups: chloroform (n=10), orange oil (n=10), eucalyptol (n=10) and control (n=10). Solvents were applied to a reservoir created on the coronal root third using Gates Glidden drills. The total time for retreatment using the solvents was 5 minutes per tooth. Following retreatment the roots were split longitudinally for SEM evaluation. SEM images were digitized, analyzed using Image ProPlus 4.5 software, and the number of dentinal tubules free of filling material from the middle and apical thirds was recorded. No significant difference was found among the solvent groups regarding the number of dentinal tubules free of root filling remnants in the middle and apical root thirds (p>0.05). However, the control group had fewer dentinal tubules free of filling material (p<0.05). Under the tested conditions, it may be concluded that there was no significant difference among the solvents used to obtain dentinal tubules free of filling material remnants.

Health of infants in an Imperial Roman skeletal sample: perspective from dental microstructure.

This study examines general health in the first year of life of a population of 127 subadults from the Imperial Roman necropolis of Isola Sacra (2nd-3rd century ACE). Health status was determined by analyzing 274 deciduous teeth from these children for Wilson bands (also known as accentuated striae), microscopic defects caused by a disruption to normal enamel development arising from some generalized external stressor. While macroscopic enamel defects, or hypoplasias, have long been used as proxies of general population health, we believe that this is the first population-wide study of microscopic defects in deciduous teeth. We used microstructural markers of enamel to attach very precise chronologies to Wilson band formation that allowed us to calculate maximum prevalence (MAP) and smoothed maximum prevalence (SMAP) distributions to portray what we believe to be a realistic risk profile for a past population of children. There appear to be two periods of high prevalence, the first beginning around age 2 months and continuing through month 5, and the second higher period beginning around month 6 and continuing through month 9. These results are discussed in light of historical records of Roman childhood rearing practices.

The effect of two different root canal sealers and smear layer on resistance to root fracture.

The purpose of this in vitro study was to test the effect of Ketac-Endo (KE) and AH 26 on resistance to root fracture and also to evaluate the effect of smear layer. Seventy-two human maxillary canine teeth were randomly divided into six groups (n = 12) and were prepared using six different methods: group 1: KE, without smear layer (smear -); group 2: KE, with smear layer (smear +); group 3: AH 26, smear (-); group 4: AH 26, smear (+); group 5 (negative control): nonprepared; group 6 (positive control): prepared but unfilled. After storing 1 week in 100% humidity at 37 degrees C, the coronal lingual walls and root canal spaces were lowered 2 mm below the buccal walls of the roots. The samples were placed into acrylic resin blocks so that 10 mm of buccal roots were exposed and were placed in a specially designed steel pad at an angle of 15 degrees to the long axis of the root. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force required to fracture each tooth was recorded as kg and statistically analyzed using one-way analysis of variance and Duncan tests. The results indicated that instrumentation of the root canals significantly weakened the tooth structure to fracture (p < 0.05). The canals obturated with either sealer were significantly stronger than roots whose canals were instrumented but not obturated (p < 0.05), and there was no difference between the sealers. The presence or absence of the smear layer did not cause any significant effect on the root fracture resistance of the teeth (p > 0.05).

Dietary difference and microwear on the teeth of late stone age and early modern people from western Japan.

A small sample of human teeth from western Japan was examined under a scanning electron microscope. All were from sites of two different ages; a Late Stone Age site dating from approximately 4,000 B.P., and an Early Modern site dating from 150-200 B.P. SEM analyses reveal that the scratches on the teeth from the Late Stone Age site tend to be larger and more frequent than those on the teeth from the Early Modern site. These microwear difference may be related to dietary difference between two populations.