Stage Of Eruption Research Articles

Insights into Wisdom Tooth Eruption Patterns Among the Student of Sahara Medical College Narowal: A Comprehensive Comparative Analysis

Objective: The time of eruption of wisdom tooth predicts the age of the person. Material and Methods: Study holds a comparative analysis of 293 students regarding wisdom tooth eruption status was categorized into fully erupted, partially erupted, un-erupted or surgically maneuvered. Statistical analysis, including descriptive statistics and correlation analysis, was performed to establish relationships between age and eruption status. Results: Preliminary findings suggest a statistically insignificant relationship between the age of the students and the eruption status of their wisdom teeth. The majority of students aged 19-23 years exhibited various stages of wisdom tooth eruption. Discussion: The results suggestion indicate that there is a discernible correlation between the age of individuals (within the age group of 19-23 years) and the eruption status of their wisdom teeth. Conclusion: Estimation of age based on the eruption time of wisdom teeth holds promise as a non-invasive and easily accessible method. Within the specific age range of 19-23 years the wisdom tooth is inconclusive.

The geothermal magmatic system at the northern Rahat volcanic field, Saudi Arabia, revealed from 3D magnetotelluric inversion

Harrat Rahat (HR) volcanic field is one of the most prominent volcanic areas in western Saudi Arabia, as it is a promising site for geothermal energy. HR has been intensively studied from a geologic point of view. Detailed inspections distinguished 12 stages of volcanic eruption with characteristic volcanics and age intervals. The area is seismologically active and suffered a swarm of earthquake events in 1999. Magnetotelluric measurements were conducted across the northern HR for deep electrical imaging to provide a comprehensive image of the geothermal source and its impact on volcanic eruptions and seismicity. Acquisition sites (65 in total) provided a square grid with ∼5 km intervals. The recording at each site continued for 20 h on average and covered a broad band of frequencies from 1 mHz to 300 Hz. Phase tensor representations and the calculated skew angles indicated three-dimensional subsurface structures. 3D inversion was then carried out using a start model of half space with 100Ωm. The inverted model shows a main magma chamber with very low resistivities in its interior (3 Ωm). Protrusions branch upwards, or first laterally and then upwards, from the main magma reservoir. They represent magma pathways to the surface and account for various eruption locations and stages. The magma chamber is overlain by a continuous zone of higher resistivity (>500 Ωm) that depicts the cooled-down lava sheets. The tabulated and spatially mapped historical eruptions are projected on the results of the 3D MT inversion in the form of slices cut at various depths to obtain clues about the details observed in the model. The epicenters of the 1999 swarm showed no direct spatial matching with features of the inverted model. Similarly, the foci positions are concentrated in the subsurface away from the geothermal source. This confirms the model, as the epicenters usually exist at zones of faults and fractures in the crust, even if the source of stresses that induce seismicity originates away from them. The rocks near the thermal source are ductile and cannot be a source of an elastic rupture. We conclude that the thermal magma reservoir is shallow (10–25 Km), of a large spatial extent (∼1000 km2), impacts surface features and induces earthquake activities.

Effect of Feeding Pattern and Salivary Level of Growth Hormone on the Stage of Primary Tooth Eruption

Introduction: We aimed to evaluate the effect of feeding pattern and salivary level of growth hormone on the stage of primary tooth eruption among infants aged 6 to 18 months. Methods: The sample size of this analytical cross-sectional study was 300 healthy infants from Karbala, Iraq. Feeding pattern answered by the parents, stage of dental eruption assessed according to criteria described by Damodar P. Swami, and level of salivary growth hormone determined using an ELISA assay. Data were analyzed via a linear regression model using R software. Results: The model (adjusted R 2: 0.668) showed the feeding pattern (beast, bottle, or mix), gender, and salivary level of growth hormone were not significant predicators for the stage of primary tooth eruption (p > 0.05). Yet, age was a significant predicator (p < 0.001). Conclusion: The infant’s feeding pattern and salivary level of growth hormone did not affect the timing of the eruption of primary teeth.

Infrared Spectroscopy to Analyze Sexual Dimorphism of Hard Dental Tissue Maturation at Eruption in Patients with Connective Tissue Dysplasia.

The aim of this study was to research the biochemical changes in the hard tissues of the lower "wisdom" teeth, which are at the stage of eruption, with connective tissue dysplasia, depending on sex. The study involved 38 patients aged 17-25 years, who had the extraction of the lower third molars on the left and right for medical reasons. Twenty-one participants in the experiment (16 females, five males) were diagnosed with connective tissue dysplasia; the remaining 17 were healthy and made up the control group (11 females, six males). Samples of enamel, dentin, and enamel-dentin junction were dried to constant weight and examined in tablets pressed in a mixture with potassium bromide on an FT-801 Fourier transform infrared (FT-IR) spectrometer (NPF Simex, Russia) in the range of 500-4000 cm-1. In the IR spectra of the enamel, enamel-dentin junction, and dentin, the absorbance ratio of amide I and II changed significantly and the absorbance of the absorption band of phosphate ions decreased from enamel to dentin. Differences between groups with and without connective tissue dysplasia increased in the following series: dentin, enamel-dentin junction, and enamel. With connective tissue dysplasia, a change in the ratio of the intensities of the absorption bands of amide I and phosphate ions was observed. Normally, the content of organic substances in the enamel of the teeth in the males group is lower than in the females group. Against the background of connective tissue dysplasia, the content of organic substances in the enamel in women decreased while in men it increased, which confirmed the presence of sexual dimorphism during the maturation of hard dental tissues at the eruption stage. The study confirms the opinion of many researchers about the significant role of collagen proteins, which, together with non-collagen proteins, are involved in the development and maturation of dental hard tissues, which are characterized by pronounced heterogeneity and sexual dimorphism in the group with connective tissue dysplasia.

Exposure of suckling rats to hexavalent chromium (CrVI) alters bone formation at the base of the alveolus causing a delay in tooth eruption

ObjectivesHexavalent chromium (CrVI)-exposure of suckling rats has been shown to delay tooth eruption. However, the effects of CrVI-exposure on bone formation at the base of the alveolus, which provides a motive force for tooth eruption in the early stages of the process, remain unknown. The present work sought to evaluate the effect of CrVI-exposure on bone formation at the base of the alveolus during the intraosseous stage of tooth eruption in suckling rats, using histomorphometric and immunohistochemical studies. MethodsExperimental animals received 12.5 mg/kg-bw/day of potassium dichromate dissolved in saline solution by gavage starting on day 4 of the experiment; controls similarly received an equivalent volume of saline. All the animals were euthanized at the age of 9 days. The base of the developing alveolus at the level of the mesial root of the first lower molar was analyzed histomorphometrically and immunohistochemically. Data were statistically analyzed using student's t-test, with statistical significance set at p < 0.05. ResultsCrVI-exposed animals showed lower bone volume and height at the base of the alveolus, a significant preponderance of bone rest on the surface adjacent to the dental follicle, and a significantly lower percentage of positive Runt-related transcription factor-2 (RUNX2+) osteoblasts and a significantly higher number of mesenchymal-like RUNX2+ cells at the latter site. ConclusionCrVI-exposure during lactation affects bone formation at the base of the developing alveolus, delaying tooth eruption. These findings underscore the importance of controlling drinking water levels of toxic substances since their effects can alter the growth and development of individuals exposed during early childhood.

The outcomes of auto-transplanted premolars in the anterior maxilla following traumatic dental injuries.

Tooth auto-transplantation is a treatment option, which is often not considered to replace anterior maxillary incisors in children and adolescents. There are multiple prognostic factors that may influence the outcomes of premolar auto-transplantation, but there is limited evidence from human studies. The aim of this study was to report the outcomes of auto-transplanted premolars in the anterior maxilla following traumatic dental injuries (TDIs) and to identify their prognostic factors. The clinical records of patients who had premolars transplanted in the anterior maxilla following TDI, with appropriate radiographs and a minimal of 1-year follow-up, were reviewed retrospectively. A specific data extraction form was developed, tested and used to collect information for the prognostic factors and outcomes. The cohort included 120 patients with 144 auto-transplanted premolars. The mean age was 12.2 years (±2.0), and the mean observation period was 3.7 years (±1.8). The success rate was 80%, and the survival rate was 93%. Unfavourable outcomes included external replacement resorption in 12.5%, uncontrolled external inflammatory resorption in 2.7%, and both resorption types in 4.9% of teeth. Periodontal healing was significantly associated with donor tooth root maturity, graft handling at the time of surgery including ease of donor tooth extraction and placement at the recipient sites, recipient site alveolar bone status, and post-operative transplant mobility. Seventy-four teeth (53.4%) were immature at the time of transplantation where pulp revascularisation was anticipated, and 52 (70%) of those had radiographic and clinical signs of pulp healing. Pulp healing was significantly related to donor tooth eruption stage, ease of extraction of donor tooth, and ease of placement in the recipient site. Good outcomes were observed for premolar teeth auto-transplanted in the anterior maxilla. The main prognostic factors were ease of extraction of donor tooth and ease of placement in the recipient sites and donor tooth root maturity.

Assessment of Oral Hygiene, Gingival, and Periodontal Health, and Teeth Eruption among Type 1 Diabetic Saudi Children.

To determine the differences between type 1 diabetic children and healthy children regarding oral hygiene, gingival and periodontal health, and permanent teeth eruption.Materials and methods: A case-control study was conducted on 80 children (40 type 1 diabetic children and 40 healthy children) aged 6-12-year-old. The groups were further divided into subgroups (early and late mixed dentition). All study aspects were examined clinically using the simplified oral hygiene index, Löe and Silness gingival index, clinical attachment loss (CAL), and Logan and Kronfeld stages for tooth eruption. The data were analyzed using Fisher's exact test, chi-squared test, and logistic regression models. A p-value of ≤0.05 was the threshold for statistical significance. No significant difference was found between diabetic and healthy children regarding oral hygiene and gingival health. Most children had poor oral hygiene (52.5% in the case group and 60% in the control group), with fair gingival health (70% in the case group and 55% in the control group). Diabetic children had significantly (p = 0.05) more periodontitis than healthy children. Teeth in the advanced stage of the eruption were significantly higher in diabetic than control subjects (p = 0.048 in stage V and p = 0.003 in stage VI). Older diabetic children in late mixed dentition exhibited accelerated eruption. Periodontitis was significantly more common in diabetic than in healthy children. The advanced stage of the eruption was significantly higher in diabetic than in control subjects. Type 1 diabetic children had more periodontal disease and advanced stage of permanent teeth eruption compared to healthy children. Therefore, periodic dental evaluation and a strong preventive plan for diabetic children is crucial. Mandura RA, El Meligy OA, Attar MH, et al. Assessment of Oral Hygiene, Gingival, and Periodontal Health, and Teeth Eruption among Type 1 Diabetic Saudi Children. Int J Clin Pediatr Dent 2022;15(6):711-716.

The Cross Equatorial Transport of the Hunga Tonga‐Hunga Ha'apai Eruption Plume

AbstractOn 15 January 2022, the Hunga Tonga‐Hunga Ha'apai (HT) eruption injected SO2 and water into the middle stratosphere. Shortly after the eruption, the water vapor anomaly moved northward toward and across the equator. This northward movement appears to be due to equatorial Rossby waves forced by the excessive infrared water vapor cooling. Following the early eruption stage, persistent mid‐stratospheric water vapor and aerosol layers were mostly confined to Southern Hemisphere tropics (Eq. to 30°S). However, during the spring of 2022, the westerly phase of the tropical quasi‐biennial oscillation (QBO) descended through the tropics. The HT water vapor and aerosol anomalies were observed to again move across the equator coincident with the shift in the Brewer‐Dobson circulation and the descent of the QBO shear zone.

A newly recorded Cryogenian-Ediacaran Dokhan Volcanic caldera with resurgent uplift in the Arabian-Nubian Shield, southwest Safaga, Egypt

The late Neoproterozoic Dokhan Volcanics (DV) of the Egyptian Eastern Desert (northern Arabian-Nubian Shield), were investigated at Gebel Nuqara, near the boundary between the Northern and Central Eastern Deserts. In particular, the nature of the peculiar circular and annular regional structures at Nuqara, were targeted for study. This included exploring the relationships of DV and intrusive units to each other and to regional dikes and faults. The central part of the Nuqara DV exposures consists of two volcanic units: 1) “Older DV” (intermediate varieties, dominantly andesites; 659 ± 16 Ma), with associated arc granitoids (663.2 ± 8.4 Ma), followed by andesite dikes (636.9 ± 7.2 Ma); and 2) “Younger DV” (acidic varieties; 602.3 ± 4.4 Ma for rhyolites, and 589.4 ± 6.1 Ma for rhyolite porphyry). This central area of DV units is enclosed within an annular intrusion of granite. The geochemical data for the Nuqara DV reveal intermediate low-silica adakitic (basaltic-andesite and andesite) and acidic high-silica adakitic (rhyolite and rhyolite porphyry). Both adakite groups share a common geochemical trend, and show evidence for magma diversification via fractional crystallization. The Nuqara DV is identified as a caldera sequence, with resurgent uplift, based on a positive comparison of the volcanic morphology, lithology, structure and mechanism of DV eruptions in the study area with those of other resurgent calderas. The geodynamic setting, volcanic architecture, and geochemistry of the DV, as well as its in-situ zircon LA–ICP–MS estimated ages, allow recognition of a series of eruptive stages, leading to collapse to form the Nuqara caldera, followed by resurgent uplift of the caldera floor during intrusion of rhyolite porphyry domes. The resurgent caldera model assigns a greater significance for the rhyolite porphyry as the exposed top of a sub-volcanic magma chamber. Resurgence is viewed as resulting from increased pressure or volume changes in the magma reservoir. A consequence of resurgence was uplift and erosion of the previous collapse-related topography.

GEOPHYSICAL EFFECTS OF THE ACTIVE STAGE OF THE STROMBOLI VOLCANO ERUPTION ON OCTOBER 9, 2022

Using the results of instrumental observations carried out in the surface atmosphere, the response of the microbaric background, variations of the Earth’s magnetic and electric fields to the paroxysmal activity of the Stromboli volcano (October 9, 2022, Italy) is analyzed. It is shown that the active stage of a volcanic eruption was accompanied by the generation of an acoustic signal and pronounced variations in the geomagnetic and atmospheric electric fields at considerable distances both during the period of volcano activity and during the arrival of an infrasonic wave at the observation point. It was also noted that the volcanic eruption caused a response in the ionosphere in the form of a change in the critical frequency of the F2 layer.

Monitoring of ductile–brittle transition mechanisms in sapphire ultra-precision grinding used small grit size grinding wheel through force and acoustic emission signals

Progressive ultra-precision grinding experiments used small grit size grinding wheels were performed to investigate the ductile–brittle transition process of sapphire, force and AE signals were employed to monitor the material removal behavior. Precision dressing and measurement of circular arc grinding wheels were performed to meet the minimum grinding depth for ultra-precision grinding. A grinding force model was proposed to interpret the grinding forces in different materials removal modes. A continuous complete ductile–brittle transition process was observed and monitored, the progressive grinding was divided into three stages: ductile dominant, ductile–brittle transition and brittle eruption. The grinding force, surface profile, micro morphology and brittle fracture percentage were discussed. Brittle fracture will not entirely occur, but rather brittle fracture and ductile grooves were coexisted on the surface in the brittle eruption stage, which was attributed to the grinding characteristics of small grit wheels. In addition, raw AE signals and multiple transformation forms were utilized to monitor the material removal behavior and their respective roles were analyzed. The Fourier transform, discrete wavelet, continuous wavelet and wavelet coefficients in different stages can all establish a mapping relationship with material removal modes.

Use of third molar eruption based on Gambier's criteria in assessing dental age.

The biological aspects of determining the dental age of subadults represent an important interdisciplinary scientific link with applications in criminal law and in forensic anthropology and dentistry. In criminal procedural law, it is necessary to determine the exact age of an undocumented person in view of the application of the provisions on juvenile offenders and minor victims. Chronological age can be estimated from the development of the third molars, as these are the only teeth that develop at the age of 18. The aim of this study was to verify the applicability of the Gambier method based on the eruption of the third permanent molars in the mandible and maxilla, to contribute to forensic age assessment. The analyzed group that met the criteria consisted of 811 orthopantomograms (OPGs) (339 females and 472 males) between the ages of 13 and 25years. The OPGs were retrospectively analyzed according to the method of Gambier et al. (Int J Legal Med 133:625-632, 29), which refers to the eruption stages of the third molar. Differences between eruption stages of maxillary and mandibular third molars were statistically significant in both biological sexes. Intersexual differences in mean age were significant only at stage 3 for any M3 tooth and at stage 1 for mandibular M3. There were no statistically significant differences between the left and right mandibular and maxillary third molars, respectively. Differences between mandibular and maxillary M3 were significant only for stage 1 in males on the left side and for stage 2 in both sexes and sides. The method used allowed the best classification of individuals into minor and adult groups (based on phase D-90.41% of individuals, based on the third stage of the mandibular left third molar-86.29%). Based on the results obtained, we can assume that the method cannot be used alone in the initial examination of living individuals, since all four third molars must be assessed and there are no additional findings from practice.

General ideas about the stages, classifications, pathological conditions during the lower third molars eruption in humans. Literature review. Part 2

The article is a review of literature data on the stages, classifications, pathological conditions during the eruption of the lower third molars in humans. The authors analyzed the established knowledge about clinical and morphological changes at various stages of eruption of the lower third molars, studied new data describing the pathogenetic, histological and biochemical features of their development, packaging, movement to the occlusal plane. The literature review helped to identify a series of current trends that define a number of key hypotheses that summarize the accumulated material and indicate different opinions on the topic under study, which confirms the prospects and relevance of continuing research.

General ideas about the stages, classifications, pathological conditions during the lower third molars eruption in humans. Literature review. Part 1

The article is a review of literature data on the stages, classifications, pathological conditions during the eruption of the lower third molars in humans. The authors analyzed the established knowledge about clinical and morphological changes at various stages of eruption of the lower third molars, studied new data describing the pathogenetic, histological and biochemical features of their development, packaging, movement to the occlusal plane. The literature review helped to identify a series of current trends that define a number of key hypotheses that summarize the accumulated material and indicate different opinions on the topic under study, which confirms the prospects and relevance of continuing research.

CHEMICAL AND TEXTURAL STUDIES OF THE YOUNGEST PYROCLASTIC DEPOSITS AT MT. SEMINUNG (SOUTH SUMATRA, INDONESIA): A WINDOW FOR UNDERSTANDING THE EXPLOSIVE BEHAVIOR OF A POST-CALDERA VOLCANO

The youngest tephra deposits of Seminung Volcano in South Sumatra, Indonesia, was studied by addressing the stratigraphy (field data), componentry, petrography, glass and mineral compositions, and textural analysis of vesicles to interpret the magmatic system and eruption dynamics. Based on the componentry and grain size characteristics, the section is divided into three different units: (1) massive block and ash, (2) interbedded ash and lapilli, and (3) massive lapilli. All units include grey pumice (GP), brown pumice (BP), and scoria (SC) as the main juvenile types, while porphyritic lava occurs as the non-juvenile phase (lithics). Noteworthy, minor banded pumice (BaP) can be observed in all units, and accretionary lapilli (AL) is exclusive in the interbedded ash and lapilli unit. The similarity in mineralogy and the linear correlation of all major elements of glass compositions suggest that grey and brown pumice originated from the same shallow, biotite-bearing more silicic magma (64.5-74.9 wt. % ), while scoria originates from the deeper, biotite-free less silicic magma (62.1-69.2 wt. % ). The fact that grey pumice shows higher silica content and pheno-bubble fraction with lower phenocryst content than brown pumice suggests the rough stratification of the more silicic magma reservoir. Furthermore, the more silicic magma was likely intruded by the deeper less silicic magma, as indicated by the bimodal distribution of anorthite (An#) in grey and brown pumices (i.e. the peak of the high anorthite content is similar to that of scoria). Thus, the accumulation of pheno-bubble and magmatic recharge were likely responsible for triggering the eruption. Finally, the fact that juvenile clasts from units 2 and 3 had the highest matrix-vesicle number density (MVND) implies that the eruption intensity reached its peak towards the final eruption stage.

Clinical Profile, Complications and Outcomes of Measles among Children: An Observational Study from a Tertiary Care Hospital, South Gujarat, India

Introduction: Measles is re-emerging as an infectious disease in children and hence the prevalence has been increasing worldwide. According to the World Health Organisation (WHO), in the year 2018, more than 140,000 deaths occurred globally due to measles and its complications; most common in children &lt;5 years of age. Aim: To evaluate the clinical profile of measles and its complications leading to death in children for better immunisation coverage and prevention of the disease. Materials and Methods: This was a prospective, observational study carried out in the Department of Paediatrics, New Civil Hospital (tertiary care hospital), Surat, Gujarat, India. Patient data was collected from January 2021 to December 2021 and data was analysed from January 2022 to June 2022. Study was done on all children with history of fever with rash and laboratory confirmed positive patients for measles Immunoglobulin M (IgM) antibody titer. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) software version 27.0. Results: During the study period only, 42 children with fever and rash had laboratory confirmed measles IgM positive antibody titre. Out of total, 42.86% of the study participants belonged to 1-4 years age group and 50% were unvaccinated. Males were more affected than female. Majority (81%) of cases occurred during late winter and spring seasons and most (78.57%) of the patients belonged to urban slum areas. Most common presenting complaint observed was maculopapular rash in all the children. Majority (95.24%) of the children were in eruptive stage of the disease. A total of 31 patients out of 42 developed complications with pneumonia as most common 38.71% children. All the patients recovered completely and were discharged from the hospital. Conclusion: There was decreasing trend of measles in young children. It can be due to recent immunisation campaigns and better coverage. Half of the patients in study were unvaccinated which indicates, there’s still work left to be done to immunisation scheme for better coverage.

Association between obesity and early tooth eruption in adolescents: Findings from a popu-lation-based cohort study in southern Brazil.

Obesity is a prevalent chronic condition affecting children and adults worldwide, and it seems to influence the timing of tooth eruption. The aim of this study was to assess the as-sociation between weight status at age 12 and the eruption of permanent teeth at ages 12 and 14-15 among schoolchildren from southern Brazil. A cross-sectional survey was conducted in Porto Alegre, southern Brazil, and included a representative sample of 1,528 12-year-old schoolchildren. After 2.5 years, 801 individuals were reexamined. Baseline data collection included a questionnaire, the record-ing of anthropometric measures (height and weight), and clinical examination to register the number of erupted permanent teeth. At follow-up, the eruption stage of second perma-nent molars was recorded. Statistical analysis used Poisson regression. Overweight and obese individuals were 32% and 88% more likely to have com-plete permanent dentition at age 12, respectively (overweight, PR=1.32, 95%CI=1.13-1.55; obese, PR=1.88, 95%CI=1.75-2.02). Obese 12-year-olds were more likely to present erupt-ed #17, #27, #37, and #47 at age 12 and to present completely erupted second molars at age 14-15 than normal weight ones. This population-based study found a significant association between over-weight/obesity at age 12 and early tooth eruption at ages 12 and 14-15 among schoolchil-dren from southern Brazil. Key words:Tooth eruption, Obesity, Permanent teeth, Epidemiology.

On the Nature of the Three-part Structure of Solar Coronal Mass Ejections

Coronal mass ejections (CMEs) result from eruptions of magnetic flux ropes (MFRs) and can possess a three-part structure in white-light coronagraphs, including a bright front, dark cavity, and bright core. In traditional opinion, the bright front forms due to the plasma pileup along the MFR border, the cavity represents the cross section of the MFR, and the bright core corresponds to the erupted prominence. However, this explanation on the nature of the three-part structure is being challenged. In this paper, we report an intriguing event that occurred on 2014 June 14 that was recorded by multiple space- and ground-based instruments seamlessly, clearly showing that the CME front originates from the plasma pileup along the magnetic arcades overlying the MFR, and the core corresponds to a hot-channel MFR. Thus the dark cavity is not an MFR; instead it is a low-density zone between the CME front and a trailing MFR. These observations are consistent with a new explanation on the CME structure. If the new explanation is correct, most (if not all) CMEs should exhibit the three-part appearance in their early eruption stage. To examine this prediction, we make a survey of all CMEs in 2011 and find that all limb events have the three-part feature in the low corona, regardless of their appearances in the high corona. Our studies suggest that the three-part structure is the intrinsic structure of CMEs, which has fundamental importance for understanding CMEs.

Long-term change of the eruption activities of Sakurajima volcano, Japan, inferred from the fallout tephra deposits

Stratigraphic analysis of fallout tephra deposits in and around a volcano provides a framework for understanding the long-term temporal change in the volcano’s activities. Here, we reconstruct the evolution of the volcanic activities of Sakurajima volcano based on reconstructed tephra stratigraphy by original field surveys, compilations of geological and archeological data, and new 14C dating. We define three eruption stages of Stage 1 (30–24 ka), Stage 2 (12.8–4.8 ka), and Stage 3 (4.5 ka–present), based on a major hiatus and shifting of the volcanic centers. Stages 2 and 3 are further subdivided according to the predominant mode of volcanic activity. Revised distribution of tephra deposits indicates that a total of 14.5 km3 (5.8 km3 dense rock equivalent) of fallout tephra has erupted from Sakurajima. Among them, Stage 2a (13–8 ka) produced the largest volume of tephra fallout deposits, suggesting that Sakurajima peaked in magma discharge during Stage 2a (2.9 km3/kyr) and then decreased rapidly toward Stage 2b (8–4.8 ka; 0.07 km3/kyr). The eruption of large-volume tephra deposits in Stage 2a, followed by the development of a thick volcanic ash layer in Stage 2b, indicates the eruption style shifted from explosive pumice eruptions in Stage 2a to ash-producing Vulcanian activity in Stage 2b, with decreasing magma discharge rate. Thick volcanic ash deposits covered by several fallout tephra deposits during Stage 3 also reflect a shift in activity from repeated Vulcanian explosions with lava effusions in Stage 3a (4.5–1.6 ka) to predominantly pumice eruptions during the historical period (Stage 3b) with an increasing magma discharge rate. The case study of Sakurajima presented here demonstrates that the combined analysis of the distribution, stratigraphy, and age of pumice fall layers with the lava and pyroclastic cone deposits on the volcanic edifice is a powerful tool for deciphering the growth history of complex stratovolcanoes.

The role of the endocannabinoid system in tooth eruption: An ex vivo study.

The aim was to characterise the endocannabinoid system (ECS) in the dental pulp of teeth at different stages of eruption. Pulp of: erupted premolars (EPM), third molars in pre-eruptive (PThM), intraosseous (IThM) and eruptive stages (EThM) (n= 12 each group) were used. Messenger RNA expression of components of the ECS as cannabinoid receptors (CBr1 and CBr2), and anandamide synthetizing (NAPE-PLD) and degradation (FAAH) enzymes were measured by RT-PCR. Data were analysed using Student's t-test for comparisons between two groups and one-way analysis of variance and Tukey's post-test for multiple comparisons (statistical significance: p< 0.05). mRNA expression of CBr2, NAPE-PLD and FAAH was similar in the studied stages, was lower in IThM than in PThM and EThM, and the lowest in EThM (p< 0.01); of note, CBr2 mRNA expression was not detected in EThM. CBr1 mRNA did not differ significantly between IThM and PThM but was lower in EThM (p< 0.01). The absence of CBr2 and presence of CBr1 in EThM suggest the involvement of the ECS via CBr1 as a mediator of tooth and bone tissue homeostasis during tooth eruption.