Human closed and open apex premolar teeth express different toll-like receptor.

BACKGROUND: The innate immune activation which promotes inflammation responses in the dental pulp tissue leads to the progression of dentin caries. Accordingly, toll-like receptors (TLRs) are key molecules of the innate immune system that identify pathogen-associated molecular patterns (PAMPs) on microorganisms and may have a critical role in a dental injury. Therefore, this study aimed to investigate the expression of TLR2, TLR3, and TLR4 in the human dental pulp of opened and closed apex teeth. METHODS: Human dental pulps were derived from the healthy opened and closed apex premolar, in which extraction was indicated for orthodontic reasons. The extraction of RNA was performed and the gene expression determined by real-time polymerase chain reaction (RT-PCR). The result from real-time PCR was confirmed using western blot analysis. RESULTS: Real-time PCR data analysis showed that the expression TLR2 and TLR4 were significantly increased in closed apex premolar teeth compared to open apex teeth, whereas TLR3 expression was not significantly different in these two groups (p < .05). CONCLUSION: The results of the present study suggested increased expression of TLR2 and TLR4 by the maturation of the apex, which may be due to the presence of microorganisms in the normal or destructed dental pulp tissue. Thus, identifying the expression of TLRs molecules in dental pulp tissue helps to develop a deeper knowledge of the immune responses in the oral cavity.

Zirconia implant abutments supporting single all-ceramic crowns in anterior and premolar regions: A six-year retrospective study.

BACKGROUND: Clinical studies regarding zirconia implant abutments reported good survival rates in the short-term observation period. The purpose of this study was to assess the six-year clinical performance of zirconia abutments supporting all-ceramic crowns in anterior and premolar regions. METHODS: The patients received zirconia implant abutments to support all-ceramic crowns in Chang-Gung Medical Center during the period August 2010 to August 2011 were enrolled. In the following six years of observation period after the implant-crown had finished, the clinical parameters of all of the included patients were registered on a special form. The records regarding the following variables: age, gender, implant location, the condition of edentulous site before implant placement, esthetic performance at baseline, presence or absence of technical complications, and biological outcomes were registered and scrutinized for evaluation. RESULTS: Out of the 32 zirconia implant abutments and 32 all-ceramic crowns that were followed for six years. Neither abutments nor crowns were lost, yielding 100% survival rates for both zirconia abutments and crowns. The esthetic outcomes were excellent except that a score of 2 was given to two restorations. With regard to technical complications, there was one instance of abutment screw loosening, two cases of veneering ceramic chipping, one restoration with occlusal roughness, and three instances of crowns loosening. Overall, the success rates were 96.8% and 81.2% for abutments and crowns respectively. In biological performance, only 1 implant was classified in group II (satisfactory survival) in the Misch classification, while all the others were classified in group I (excellent). CONCLUSIONS: Zirconia abutments supporting all-ceramic crowns demonstrated high survival rate, good biological and esthetic results. While some technical complications were frequently observed, the complication-free rates were 96.8% for abutments and 81.2% for crowns in the medium-term observation period.

Polyamines and microbiota in bicuspid and tricuspid aortic valve aortopathy.

Polyamines are small aliphatic cationic molecules synthesized via a highly regulated pathway and involved in general molecular and cellular phenomena. Both mammalian cells and microorganisms synthesize polyamines, and both sources may contribute to the presence of polyamines in the circulation. The dominant location for microorganisms within the body is the gut. Accordingly, the gut microbiota probably synthesizes most of the polyamines in the circulation in addition to those produced by the mammalian host cells. Polyamines are mandatory for cellular growth and proliferation. Established evidence suggests that the polyamine spermidine prolongs lifespan and improves cardiovascular health in animal models and humans through both local mechanisms, involving improved cardiomyocyte function, and systemic mechanisms, including increased NO bioavailability and reduced systemic inflammation. Higher levels of polyamines have been detected in non-dilated aorta of patients affected by bicuspid aortic valve congenital malformation, an aortopathy associated with an increased risk for thoracic ascending aorta aneurysm. In this review, we discuss metabolism of polyamines and their potential effects on vascular smooth muscle and endothelial cell function in vascular pathology of the thoracic ascending aorta associated with bicuspid or tricuspid aortic valve.

Oxygen Saturation in the Dental Pulp of Maxillary Premolars in Different Age Groups - Part 1.

The aim of this study was to determine oxygen saturation levels in the dental pulp of maxillary premolars in different age groups. A total of 120 human maxillary premolars with normal dental pulps were selected covering the following age groups: 20-24, 25-29, 30-34, 35-39 and 40-44 years (n=24 each group). Oxygen saturation was assessed using pulse oximetry. Analysis of variance was used to assess differences in oxygen saturation levels and Tukey's test was used to identify the age groups that differed from each other. Significance was set at 0.05. Mean oxygen saturation of 120 premolars was 86.20% considering all age groups. Significantly reduced levels were found in the oldest group compared to the other groups: 40 to 44 years - 80.00% vs. 89.71, 87.67, 88.71, and 84.80% for age groups 20-24, 25-29, 30-34, 35-39 years, respectively. The mean oxygen saturation levels were similar between 20 and 39 years of age (86.20%) in the whole sample, but reduced significantly in the 40-44-year age group, suggesting that older patients present lower oxygen saturation results even in the absence of pulp tissue injury.

Oxygen Saturation in the Dental Pulp of Maxillary Premolars in Different Age Groups - Part 1

Abstract The aim of this study was to determine oxygen saturation levels in the dental pulp of maxillary premolars in different age groups. A total of 120 human maxillary premolars with normal dental pulps were selected covering the following age groups: 20-24, 25-29, 30-34, 35-39 and 40-44 years (n=24 each group). Oxygen saturation was assessed using pulse oximetry. Analysis of variance was used to assess differences in oxygen saturation levels and Tukey's test was used to identify the age groups that differed from each other. Significance was set at 0.05. Mean oxygen saturation of 120 premolars was 86.20% considering all age groups. Significantly reduced levels were found in the oldest group compared to the other groups: 40 to 44 years - 80.00% vs. 89.71, 87.67, 88.71, and 84.80% for age groups 20-24, 25-29, 30-34, 35-39 years, respectively. The mean oxygen saturation levels were similar between 20 and 39 years of age (86.20%) in the whole sample, but reduced significantly in the 40-44-year age group, suggesting that older patients present lower oxygen saturation results even in the absence of pulp tissue injury.

Resumo Este estudo determinou os níveis de saturação de oxigênio (SaO2) em polpas dentárias de pré-molares superiores em diferentes faixas etárias. Foram selecionados 120 pré-molares superiores humanos com polpas dentárias normais, abrangendo os seguintes grupos etários: 20-24, 25-29, 30-34, 35-39 e 40-44 anos (n=24 para cada grupo). A saturação de oxigênio foi avaliada utilizando oximetria de pulso. A análise de variância foi utilizada para avaliar diferenças nos níveis de saturação de oxigênio, e o teste de Tukey foi utilizado para identificar os grupos etários que diferiam uns dos outros. A significância foi estabelecida em 0,05. A saturação média de oxigênio foi de 86,20% considerando todos os grupos etários. Níveis significativamente reduzidos foram encontrados no grupo de indivíduos de maior idade em comparação aos outros grupos: 40 a 44 anos - 80,00% vs. 89,71, 87,67, 88,71 e 84,80% para os grupos etários 20-24, 25-29, 30-34, 35-39 anos. Os níveis médios de saturação de oxigênio foram semelhantes entre os 20 e os 39 anos de idade (86,20%), mas reduziram-se significativamente na faixa etária de 40-44 anos, sugerindo que os pacientes mais idosos apresentam menor saturação de oxigênio mesmo na ausência de lesão do tecido pulpar.

Double-edged-sword effect of IL-1ß on the osteogenesis of periodontal ligament stem cells via crosstalk between the NF-κB, MAPK and BMP/Smad signaling pathways.

Microenvironmental conditions can interfere with the functional role and differentiation of mesenchymal stem cells (MSCs). Recent studies suggest that an inflammatory microenvironment can significantly impact the osteogenic potential of periodontal ligament stem cells (PDLSCs), but the precise effects and mechanisms involved remain unclear. Here, we show for the first time that interleukin-1ß (IL-1ß) has dual roles in the osteogenesis of PDLSCs at concentrations ranging from physiologically healthy levels to those found in chronic periodontitis. Low doses of IL-1ß activate the BMP/Smad signaling pathway to promote the osteogenesis of PDLSCs, but higher doses of IL-1ß inhibit BMP/Smad signaling through the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling, inhibiting osteogenesis. These results demonstrate that crosstalk between NF-κB, MAPK and BMP/Smad signaling mediates this dual effect of IL-1ß on PDLSCs. We also show that the impaired osteogenesis of PDLSCs results in more inflammatory cytokines and chemokines being released, inducing the chemotaxis of macrophages, which further clarifies the role of PDLSCs in the pathogenesis of periodontitis.

EDTA soluble chemical components and the conditioned medium from mobilized dental pulp stem cells contain an inductive microenvironment, promoting cell proliferation, migration, and odontoblastic differentiation.

BACKGROUND: The critical challenge in tissue engineering is to establish an optimal combination of stem cells, signaling morphogenetic molecules, and extracellular matrix scaffold/microenvironment. The extracellular matrix components of teeth may be reconstituted as an inductive microenvironment in an ectopic tooth transplantation bioassay. Thus, the isolation and identification of the chemical components of the inductive microenvironment in pulp/dentin regeneration will accelerate progress towards the goal of tissue engineering of the tooth. METHODS: The teeth demineralized in 0.6 M hydrochloric acid were sequentially extracted by 4.0 M guanidine hydrochloride (GdnHCl), pH 7.4, and 0.5 M ethylenediaminetetraacetic acid (EDTA), pH 7.4. The extracted teeth were transplanted into an ectopic site in severe combined immunodeficiency (SCID) mice with mobilized dental pulp stem cells (MDPSCs). The unextracted tooth served as a positive control. Furthermore, the soluble components for the inductive microenvironment, the GdnHCl extracts, or the EDTA extracts together with or without MDPSC conditioned medium (CM) were reconstituted systematically with autoclaved teeth in which the chemical components were completely inactivated and only the physical microenvironment was preserved. Their pulp/dentin regenerative potential and angiogenic potential were compared 28 days after ectopic tooth transplantation by histomorphometry and real-time RT-PCR analysis. RESULTS: Expression of an odontoblastic marker, enamelysin, and a pulp marker, thyrotropin-releasing hormone degrading enzyme (TRH-DE), was lower, and expression of a periodontal cell marker, anti-asporin/periodontal ligament-associated protein 1 (PLAP-1), was higher in the transplant of the EDTA-extracted teeth compared with the GdnHCl-extracted teeth. The autoclaved teeth reconstituted with the GdnHCl extracts or the EDTA extracts have weak regenerative potential and minimal angiogenic potential, and the CM significantly increased this potential. Combinatorial effects of the EDTA extracts and the CM on pulp/dentin regeneration were demonstrated in vivo, consistent with their in-vitro effects on enhanced proliferation, migration, and odontoblastic differentiation. CONCLUSIONS: The EDTA-extracted teeth demonstrated significantly lower pulp/dentin regenerative potential compared with the GdnHCl-extracted teeth. The EDTA soluble chemical components when reconstituted with the physical structure of autoclaved teeth serve as an inductive microenvironment for pulp/dentin regeneration, promoting cell proliferation, migration, and odontoblastic differentiation.

[THE IMMUNOLOGIC INDICATORS IN PATIENTS WITH CARIES OF CONTACT SURFACES OF LATERAL TEETH].

The samplings of patients aged 18-45 years with caries of contact surfaces of lateral teeth (n=18) and healthy adults aged 18-20 years with intact teeth (n=18) were examined The saliva taken in rotary vial on empty stomach in amount of 3-4 mi served as assay for analysis. To identify secretory immunoglobulin A, interleukin lß, interleukin-4 and interferon y saliva was centrifuged during 15 min under 1500 rpm. The supernatant fluid was analyzed using enzymoimmunoassay (test-systems "Vector-Best", Novosibirsk). The registration of reaction was implemented using multiscan Labsystem under wavelength 450 nm. The content of secretory immunoglobulin A was expressed in mg/l, cytokines - in pg/ml. It is demonstrated that in patients with caries average level of interleukin lß was almost two times higher (p<0.05) than analogous indicator in healthy examined patients. In healthy patients average level of interferon γ significantly (more than in 10 times) exceeded upper limit of allowable standard and was higher (p<0.05) in comparison with such in patients with caries of contact surfaces. The analysis of content of secretory immunoglobulin A in saliva established that in healthy patients average values of the given indicator were higher (p<0.05) than in patients with caries of contact surfaces of lateral teeth. The lower content of secretory immunoglobulin A and interferon y against the background of increased level of interleukin lß was detected in saliva of patients with caries of contact surfaces of lateral teeth. This occurrence can be considered as factor predisposing to development of caries process.

Effects of the concentration and composition of in-office bleaching gels on hydrogen peroxide penetration into the pulp chamber.

UNLABELLED: In tooth whitening, the hydrogen peroxide (HP) diffuses in the enamel and dentin, reaching the pulp. This in vitro study aimed to quantify the penetration of HP in the pulp chamber in teeth submitted to bleaching agents of different concentrations of HP without calcium (HP 20% [20CF], HP 35% [35CF]) and with calcium (HP 20% [20CC], HP 35% [35CC]). METHOD: Fifty human premolars were sectioned 3 mm from the cemento-enamel junction and the pulp tissue was removed. The teeth were divided into five groups according to treatment and with a control group (n=10). An acetate buffer solution was placed in the pulp chamber of all teeth. The control group was exposed only to distilled water, while the other groups were treated with a bleaching procedure, according to the manufacturer's recommendations. After treatment, the acetate buffer solution was transferred to a glass tube in which leuco-crystal violet and peroxidase solutions were added, resulting in a blue solution. The optical density of this blue solution was determined spectrophotometrically and converted into micrograms equivalent to the HP. Data were analyzed using analysis of variance and Tukey tests (α=0.05). RESULTS: The HP concentration did not affect the HP inside the pulp chamber, but the presence of calcium significantly reduced it (p<0.0001). CONCLUSION: The amount of HP that reaches the pulp chamber depends on the bleaching protocol and the product employed, and it seems to be less affected by HP concentration.

Nemotic human dental pulp fibroblasts promote human dental pulp stem cells migration.

Dental pulp inflammation has long been perceived as a negative factor leading to pulp disruption. Previous studies have suggested that the inflammatory reaction might be a prerequisite for the burst of progenitors implicated in pulp repair. To investigate the migration of human dental pulp stem cells (hDPSCs) in response to human dental pulp fibroblasts (HDPFs) nemosis, an in vitro model of nemosis-induced inflammation in three-dimensional culture was used in this study. We observed HDPF spheroid formation and that cell-cell adhesion between HDPFs leads to necrosis. Cell death detection and cell counting kit-8 assays showed reduced live cell numbers and increased levels of cell membrane leakage in HDPF spheroids. HDPFs spheroids expressed cyclooxygenase-2 and released an increasing amount of prostaglandin E2 and interleukin-8, indicating inflammation in response to nemosis. The Transwell assays showed that the conditioned medium from HDPFs spheroids significantly induced hDPSCs migration more than the medium from the monolayer. Taken together, these results indicate that HDPFs spheroids induce nemosis and contribute to the migration of hDPSCs. This model might provide a potential research tool for studying interactions between fibroblasts and stem cells, and studies concerning nemosis-targeted stem cells might help treat pulp inflammation.

The effect of calcium hydroxide placement on pH and calcium concentration in periapical environment: an in vitro study.

AIMS: Comparing the calcium concentration and pH levels of Ca(OH) 2 medicament placing in pulp chamber and root canal. MATERIALS AND METHODS: Ninety-nine extracted human mandibular second premolars were instrumented to size #40 k file. Nine teeth served as the control group and the remaining teeth were assigned into two groups. Group 1-Ca(OH) 2 was placed in the dried pulp chamber, while root canals remained wet with normal saline; group 2-Ca(OH) 2 was placed in dried root canals. In control group, canals remained wet without medication. Each group was divided into 3 sub-groups of 15 teeth in which pH and calcium concentration were measured in three intervals of 2 days, 1 week, and 2 weeks by pH meter and atomic absorption spectrometer system, respectively. Findings were assessed using Kruskal-Wallis and t-test. RESULTS: At 1 and 2 weeks, the calcium concentration had increased without being significantly different from Ca(OH) 2 placed either in the root canal or in the pulp chamber. Ca(OH) 2 placed in the pulp chamber or root canal provided similar pH values (P=0.362). CONCLUSIONS: Placing Ca(OH) 2 in pulp chamber is as effective as placing it in the root canal.

Kinetics of interleukin-6 and chemokine ligands 2 and 3 expression of periodontal tissues during orthodontic tooth movement.

INTRODUCTION: Mechanical loading induces remodeling of the periodontal ligament and the alveolar bone and is mediated by cytokines and chemokines. In this study, we investigated the kinetics of interleukin-6 and chemokine ligands 2 and 3 levels in periodontal ligaments subjected to orthodontic forces. METHODS: We used 64 premolars in this split-mouth design study. The experimental group consisted of premolars subjected to a force of 0.980 N in the apical direction for 3 hours, 15 hours, 3 days, 12 days, or 21 days with a 0.017 × 0.025-in beta-titanium alloy cantilever. The contralateral teeth, without orthodontic appliances, were used as controls. The premolars were extracted for orthodontic reasons, and the periodontal ligaments were scraped for analysis of cytokine levels by ELISA. RESULTS: Compared with the control group, an increase in chemokine ligand 2 was observed on days 3 and 12, and increases in interleukin-6 and chemokine ligand 3 were observed on day 12 in the experimental group. CONCLUSIONS: Our data demonstrated differential expressions of interleukin-6 and chemokine ligands 2 and 3 in periodontal ligaments after mechanical loading; this might reflect the distinct roles of these molecules in the bone remodeling process.

Molecular markers of dental pulp tissue during orthodontic tooth movement: a pilot study.

Three specific orthodontic tooth movement genes, that is, FCRL1, HSPG2, and LAMB2 were detected at upper first premolar (with appliance) dental pulp tissue by using GeneFishing technique as compared to lower first premolar (without appliance). These three differentially expressed genes have the potential as molecular markers during orthodontic tooth movement by looking at molecular changes of pulp tissue.

[Gene clone and expression of Barx1 in different tooth of the mini-pig at embryonic day 40].

OBJECTIVE: To partially clone and compare the quantitative expression of tooth development-related gene Barx1 in different teeth of the mini-pig embryo at embryonic day 40, and to investigate the relationship between Barx1 spatial quantitative expression and tooth morphogenesis. METHODS: The mini-pig Barx1 genes was partially cloned and the mRNA sequences of human Barx1 genes was aligned with expressed sequence tags (EST) of pig by basic local alignment search tool (BLAST), which were assembled with DNAman v5.2.2. With designed primers, Barx1 was partially cloned in use of reverse transcription polymerase chain reaction (PCR), and tested by BLAST with all the species in NCBI database and confirmed as one part of target gene. Laser capture microdissection was used to collect tooth samples from frozen sections which were prepared before in -80°C freezer. Real-time PCR was carried out to analyze quantitative expression in different teeth. RESULTS: Partial mini-pig Barx1 gene of 698 bp was cloned. Real-time PCR showed that, glyceraldehyde-3-phosphate dehydrogenase used as loading control, the figures of 2(-ΔCT) of lower deciduous incisor, canine, the third premolar and molar were 0.000 249, 0.000 715, 0.026 096 and 0.112 656, respectively. There was a trend of increasing expression from anterior to posterior teeth. CONCLUSIONS: Barx1 gene could be related to the number or differentiation of tooth cusps.

Effect of experimentally induced occlusal trauma on substance p expression in human dental pulp and periodontal ligament.

INTRODUCTION: The purpose of this study was to quantify the effect of occlusal trauma experimentally induced with occlusal interferences on substance P (SP) expression in healthy human dental pulp and periodontal ligament. METHODS: Twenty-eight human dental pulp and periodontal ligament samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, occlusal trauma was induced with experimental occlusal interferences in half of these premolars by placing a resin block over their occlusal surface and submitting patients to chew gum for 30 minutes. The remaining healthy premolars were extracted without occlusal trauma and served as a control group. All dental pulp and periodontal ligament samples were processed, and SP was measured by radioimmunoassay. RESULTS: There was 45% and 120% greater SP expression in dental pulp and periodontal ligament, respectively, of teeth with experimentally induced occlusal trauma. Paired t test showed statistically significant differences for both human dental pulp and periodontal ligament (P = .02 and P < .001, respectively) of teeth submitted to occlusal trauma when compared with control group values. CONCLUSIONS: SP expression in human dental pulp and periodontal ligament increases when teeth are submitted to occlusal trauma experimentally induced with occlusal interferences.

Effect of strontium in combination with fluoride on enamel remineralization in vitro.

Previous studies showed that strontium (Sr) as well as fluoride (F) can enhance enamel remineralization. The aim of this study was to evaluate the effects of Sr in combination with F on enamel remineralization in vitro. Sixty enamel specimens obtained from caries free human premolars were demineralised to produce caries-like lesions. Half of each lesion was covered with nail varnish as an untreated control. The specimens were then randomly divided into F and Sr+F treatment groups. The F group was exposed to remineralizing solutions (1.5mM CaCl(2), 0.9 mM KH(2)PO(4)) containing 1 ppm, 0.1 ppm or 0.05 ppm F. The Sr+F treatment group was exposed to the same solutions including 10 ppm Sr. After 2 weeks, lesion depth, mineral loss and percentage enamel remineralization were determined using transversal microradiography. There was a significant decrease in mineral loss in all groups (p<0.001). Lesion depth was significantly reduced for all groups (p<0.05) with the exception of group F. Remineralization was significantly affected by F concentration (p=0.000). The participation of Sr resulted in a significant enhancement of remineralization (p<0.001) with a synergistic effect of the Sr+F combination (p<0.01). It was concluded that while the remineralizing process was affected by the concentration of F, there was also an interaction between F and Sr when they were used in conjunction.

The taming of the shrew milk teeth.

A characteristic feature of mammalian dentition is the evolutionary reduction of tooth number and replacement. Because mice do not replace teeth, here we used Sorex araneus, the common shrew, as a model to investigate the loss of tooth replacement. Historically, shrews have been reported to initiate the development of several, milk or deciduous teeth but these soon become rudimentary and only the replacement teeth erupt. Shrews thus offer a living example of a derived mammalian pattern where the deciduous tooth development is being suppressed. Based on histological and gene expression analyses of serial sections, we suggest that S. araneus has discernible tooth replacement only in the premolar 4 (P4) position. Both generations of teeth express Shh in the enamel knot and in the inner enamel epithelium. Nevertheless, the deciduous P4 (dP4) is reduced in size during embryogenesis and is eventually lost without becoming functional. Analysis of growth shows that P4 replaces the dP4 in a "double-wedge" pattern indicative of competitive replacement where the suppression of the deciduous tooth coincides with the initiation of its replacement. Because activator-inhibitor mechanisms have been implicated in adjacent mouse molars and in transgenic mice with continuous tooth budding, we suggest that evolutionary suppression of deciduous teeth may involve early activation of replacement teeth, which in turn begin to suppress their deciduous predecessors.

Comparison of levels of inflammatory mediators IL-1beta and betaG in gingival crevicular fluid from molars, premolars, and incisors during rapid palatal expansion.

INTRODUCTION: Previously, we reported fluctuation of the levels of the inflammatory mediators interleukin-1beta (IotaL-1beta) and beta-glucuronidase (betaG) in gingival crevicular fluid (GCF) from the maxillary first molars in adolescents undergoing rapid palatal expansion. In this study, we compared the responses of IL-1beta and betaG in the GCF of the maxillary first molars, first premolars, and central incisors during palatal expansion at the same patients. METHODS: Nine patients requiring palatal expansion were selected at the postdoctoral orthodontic clinic at Columbia University College of Dental Medicine. Each patient received periodontal prophylaxis and instructions in proper home care including rinsing with chlorhexidine. Four weeks after periodontal prophylaxis, a modified hyrax appliance was placed. The jackscrew was activated twice daily until the appropriate expansion was achieved. GCF samples were collected before and after periodontal prophylaxis and during passive wearing of the appliance, active orthodontic treatment, and retention. Fluid samples were collected with filter paper strips and analyzed by ELISA and time-dependent fluorometry for IL-1beta and betaG, respectively. The values recorded after periodontal prophylaxis were used as the baseline. Paired t tests were used to compare mediator levels at baseline with the levels obtained at each subsequent observation. RESULTS: The results validate that IL-1beta and betaG are present in the GCF of adolescents, and, although their level decreases after a strict regimen of plaque control, it increases during orthodontic or orthopedic movement. Moreover, this study demonstrates that both heavy and light forces evoke increased levels of IL-1beta and betaG, stronger forces cause higher levels of inflammatory mediators, and both IL-1beta and betaG respond to direct and indirect application of mechanical force to teeth. CONCLUSIONS: This investigation corroborates previous findings that an inflammatory process occurs during application of mechanical force to teeth. Although this inflammation is considered relatively aseptic, additional inflammation, such as that induced by plaque accumulation, must be avoided during orthodontic or orthopedic treatment.

Variation in modern human premolar enamel formation times: implications for Neandertals.

A recent study demonstrated that variation in enamel cap crown formation in the anterior teeth is greater than that in the molars from two geographically distinct populations: native indigenous southern Africans and northern Europeans. Eighty southern African and 69 northern European premolars (P3 and P4) were analyzed in the present study. Cuspal, lateral, and total enamel formation times were assessed. Although cuspal enamel formation times were not consistently different between the two populations, both lateral and total enamel formation times generally were. Bonferroni-corrected t-tests showed that southern Africans had significantly shorter lateral enamel formation time for five of the six cusps, as well as significantly shorter total enamel formation time for these same cusps. An analysis of covariance performed on the lingual cusps of the upper third and fourth premolars showed that differences in enamel formation times between these populations remained when crown height was statistically controlled. A further goal of this study was to ascertain, based on perikymata counts, what Neandertal periodicities would have to be in order for their teeth to have lateral enamel formation times equivalent to either southern Africans or northern Europeans. To this end, perikymata were counted on 32 Neandertal premolars, and the counts were inserted into regression formulae relating perikymata counts to periodicity for each population and each tooth type. Neandertal enamel formation times could be equivalent to those of southern Africans or northern Europeans only if their hypothetical periodicities fall within the range of periodicities for African apes and modern humans (i.e., 6-12 days). The analysis revealed that both populations could encompass Neandertal timings, with hypothetical periodicities based on the southern African population necessitating a lower range of periodicity (6-8 days) than those based on the northern European population (8-11 days).

Evaluation of fluoride release from teeth after topical application of NaF, SnF2 and APF and antimicrobial activity on mutans streptococci.

UNLABELLED: The objectives of this study were to evaluate and compare the amount and pattern of fluoride release from teeth after topical application of 2% NaF, 8% SnF2 and 1.23% APF at different time intervals. The growth inhibitory effects of this released fluoride ion was assessed on mutans streptococci (MS) and correlated with the fluoride release. Forty premolars divided into four groups were subjected to different topical fluoride treatments. All the teeth were immersed individually in deionized water and were transferred to containers at 1 hour, 1 day and 1 week time intervals. 240 samples in total were used for fluoride estimation by ion selective electrode method and the samples from the other subgroup were used for evaluation of antimicrobial activity on mutans streptococci (MS) by bacterial inhibition assay method. The results showed that the highest fluoride release (7.83 +/- 0.55 ppm) was seen in SnF2 treated specimens, as compared to that of NaF (3.71 +/- 0.60ppm) and APF (3.30 +/- 0.51ppm), the difference being statistically significant (P<0.01). This was observed immediately after 1 hour, followed by a drastic reduction thereafter. No zones of inhibition were observed at the released fluoride concentrations at different time intervals in the different groups. IN CONCLUSION: 8% SnF2 is expected to have greater anticaries property from the high fluoride releasing property for prolonged period of time.