Human immature dental pulp stem cells share key characteristic features with limbal stem cells

Objectives: Limbal stem cells (LSC) are self-renewing, highly proliferative cells in vitro, which express a set of specific markers and in vivo have the capacity to reconstruct the entire corneal epithelium in cases of ocular surface injury. Currently, LSC transplantation is a commonly used procedure in patients with either uni- or bilateral total limbal stem cells deficiency (TLSCD). Although LSC transplantation holds great promise for patients, several problems need to be overcome. In order to find an alternative source of cells that can partially substitute LSC in cornea epithelium reconstruction, we aimed at investigating whether human immature dental pulp stem cells (hIDPSC) would present similar key characteristics as LSC and whether they could be used for corneal surface reconstruction in a rabbit TLSCD model. Materials: We used hIDPSC, which co-express mesenchymal and embryonic stem cell markers and present the capacity to differentiate into derivative cells of the three germinal layers. TLSCD was induced by chemical burn in one eye of rabbits. After 30 days, the opaque tissue formed was removed by superficial keratectomy. Experimental group received undifferentiated hIDPSC, while control group only received amniotic membrane (AM). Both groups were sacrificed after 3 months. Results and conclusions: We have demonstrated, using immunohistochemistry and reverse transcription-polymerase chain reaction, that hIDPSCs express markers in common with LSC, such as ABCG2, integrin beta 1, vimentin, p63, connexin 43 and cytokeratins 3/12. They were also capable of reconstructing the eye surface after induction of unilateral TLSCD in rabbits, as shown by morphological and immunohistochemical analysis using human-specific antibodies against limbal and corneal epithelium. Our data suggest that hIDPSCs share similar characteristics with LSC and might be used as a potential alternative source of cells for corneal reconstruction.

Polymerization kinetics and reactivity of alternative initiators systems for use in light-activated dental resins

Objectives. The purpose of this study was to evaluate the reactivity and polymerization kinetics behavior of a model dental adhesive resin with water-soluble initiator systems. Methods. A monomer blend based on Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin, which was polymerized using a thioxanthone type (QTX) as a photoinitiator. Binary and ternary photoinitiator systems were formulated using 1 mol% of each initiator. The co-initiators used in this study were ethyl 4-dimethylaminobenzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), 1,3-diethyl-2-thiobarbituric acid (BARB), p-toluenesulfinic acid and sodium salt hydrate (SULF). Absorption spectra of the initiators were measured using a UV-Vis spectrophotometer, and the photon absorption energy (PAE) was calculated. The binary system camphorquinone (CQ)/amine was used as a reference group (control). Twelve groups were tested in triplicate. Fourier-transform infrared spectroscopy (FTIR) was used to investigate the polymerization reaction during the photoactivation period to obtain the degree of conversion (DC) and maximum polymerization rate (R-p(max)) profile of the model resin. Results. In the analyzed absorption profiles, the absorption spectrum of QTX is almost entirely localized in the UV region, whereas that of CQ is in the visible range. With respect to binary systems, CQ + EDAB exhibited higher DC and R-p(max) values. In formulations that contained ternary initiator systems, the group CQ + QTX + EDAB was the only one of the investigated experimental groups that exhibited an R-p(max) value greater than that of CQ + EDAB. The groups QTX + EDAB + DPIHFP and QTX + DPIHFP + SULF exhibited values similar to those of CQ + EDAB with respect to the final DC; however, they also exhibited lower reactivity. Significance. Water-soluble initiator systems should be considered as alternatives to the widely used CQ/amine system in dentin adhesive formulations. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Cleft lip and palate: recommendations for dental anesthetic procedure based on anatomic evidences

Patients with cleft lip and palate usually present dental anomalies of number, shape, structure and position in the cleft area and the general dentist is frequently asked to restore or extract those teeth. Considering that several anatomic variations are expected in teeth adjacent to cleft areas and that knowledge of these variations by general dentists is required for optimal treatment, the objectives of this paper are: 1) to describe changes in the innervation pattern of anterior teeth and soft tissue caused by the presence of a cleft, 2) to describe a local anesthetic procedure in unilateral and bilateral clefts, and 3) to provide recommendations to improve anesthetic procedures in patients with cleft lip and palate. The cases of 2 patients are presented: one with complete unilateral cleft lip and palate, and the other with complete bilateral cleft lip and palate. The patients underwent local anesthesia in the cleft area in order to extract teeth with poor bone support. The modified anesthetic procedure, respecting the altered course of nerves in the cleft maxilla and soft tissue alterations at the cleft site, was accomplished successfully and the tooth extraction was performed with no pain to the patients. General dentists should be aware of the anatomic variations in nerve courses in the cleft area to offer high quality treatment to patients with cleft lip and palate.

Dental calculus formation in children and adolescents undergoing hemodialysis

This study aimed to determine whether dental calculus formation is really higher among patients with chronic kidney disease undergoing hemodialysis than among controls. Furthermore, the study evaluated correlations between dental calculus formation and dental plaque, variables that are related to renal disease and/or saliva composition. The Renal Group was composed of 30 patients undergoing hemodialysis, whereas the Healthy Group had 30 clinically healthy patients. Stimulated whole saliva and parotid saliva were collected. Salivary flow rate and calcium and phosphate concentrations were determined. In the Renal Group the saliva collection was carried out before and after a hemodialysis session. Patients from both groups received intraoral exams, oral hygiene instructions, and dental scaling. Three months later, the dental calculus was measured by the Volpe-Manhold method to determine the rate of dental calculus formation. The Renal Group presented a higher rate of dental calculus formation (p < 0.01). Correlation was observed between rate of dental calculus formation and whole saliva flow rate in the Renal Group after a hemodialysis session (r = 0.44, p < 0.05). The presence of dental calculus was associated with phosphate concentration in whole saliva from the Renal Group (p < 0.05). In conclusion, patients undergoing hemodialysis presented accelerated dental calculus formation, probably due to salivary variables.

Relationship between elastic and mechanical properties of dental ceramics and their index of brittleness

The purpose of the study was to verify the effects of a number of materials' parameters (crystalline content; Young's modulus, E; biaxial flexure strength, sigma(i); Vickers hardness, VH; fracture toughness, K-Ic; fracture surface energy, gamma(f); and index of brittleness, B) on the brittleness of dental ceramics. Five commercial dental ceramics with different contents of glass phase and crystalline particles were studied: a vitreous porcelain (VM7/V), a porcelain with 16 vol% leucite particles (d.Sign/D), a glass-ceramic with 29 vol% leucite particles (Empress/E1), a glass-ceramic with 58 vol% lithium-disilicate needle-like particles (Empress 2/E2), and a glass-infiltrated alumina composite with 65 vol% crystals (In-Ceram Alumina/IC). Discs were constructed according to manufacturers' instructions, ground and polished to final dimensions (12 mm x 1.1 mm). Elastic constants were determined by ultrasonic pulse-echo method. sigma(i) was determined by piston-on-3-balls method in inert condition. VH was determined using 19.6 N load and K-Ic was determined by indentation strength method. gamma(f) was calculated from the Griffith-Irwin relation and B by the ratio of HV to K-Ic. IC and E2 showed higher values of sigma(i), E, K-Ic and gamma(f), and lower values of B compared to leucite-based glass-ceramic and porcelains. Positive correlations were observed for sigma(i) versus K-Ic, and K-Ic versus E-1/2, however, E did not show relationship with HV and B. The increase of crystalline phase content is beneficial to decrease the brittleness of dental ceramics by means of both an increase in fracture surface energy and a lowering in index of brittleness. (C) 2012 Elsevier Ltd and Techna Group Sri. All rights reserved.

Decline in dental caries among 12-year-old children in Brazil, 1980-2005

Objectives This study was conducted to determine changes in values on the decayed, missing and filled teeth (DMFT) index in 12-year-old children in Brazil between 1980 and 2005, and to correlate DMFT values with human development index (HDI) values, time, population size of municipality and fluoridation of the water supply. Methods The present study represents a retrospective ecological study using secondary data from epidemiological surveys published in indexed journals, as well as data obtained from epidemiological official surveys carried out in Brazil in 1986, 1996 and 2003, and in the State of Sao Paulo in 1998 and 2002. Units of study were represented by Brazilian municipalities holding average DMFT index values for 12-year-old children. Multiple regression analysis was used to examine the correlations among DMFT and HDI values, and time, population size and fluoridation of the water supply. Results The final database included 550 records of DMFT values in 428 different towns. Regression analysis showed statistically significant correlations between DMFT index values and time (P < 0.001), fluoridation of the water supply (P < 0.001) and size of municipality (P < 0.001). Estimated mean DMFT index values were 8.36 in 1980, 6.08 in 1985, 4.45 in 1990, 3.29 in 1995, 2.46 in 2000 and 1.86 in 2005. Conclusions Data showed a significant decrease in dental caries across the entire country, with an average reduction of 25% occurring every 5 years. General trends indicated that a reduction in DMFT index values occurred over time, that a further reduction in DMFT index values occurred when a municipality fluoridated its water supply, and mean DMFT index values were lower in larger than in smaller municipalities.

Dental caries related to quality of life in two Brazilian adolescent groups: a cross-sectional randomised study

Objectives: To analyse dental caries-related quality of life (QoL) in adolescent (1519-year-old) subjects in a suburban area (SA) and a downtown area (DA) of Bauru, Sao Paulo, Brazil, in 2009. Methods: This was a cross-sectional, randomised study. The sample consisted of 185 and 147 adolescents from the SA and DA, respectively. The caries index used was that for decayed, missing and filled teeth (DMFT) (World Health Organization criteria). The 14-item Oral Health Impact Profile (OHIP-14) was used to assess QoL. The non-parametric MannWhitney test, Spearmans correlation coefficient and chi-squared test were used in the statistical analysis. Results: The DMFT index, Significant Caries (SiC) Index and percentage of caries-free students were similar (P > 0.05) between these populations, but findings on the Care Index differed (P < 0.05). There was a correlation between the DMFT index and OHIP-14 score in SA subjects (mean DMFT index = 3.01) in the dimensions of physical pain (r = 0.25; P < 0.01) and psychological disability (r = 0.17; P = 0.02). The DMFT index in DA subjects (mean DMFT index = 2.95) showed a correlation with functional limitation (r = 0.19; P = 0.02). The correlation in SA subjects between the caries component (mean = 1.22) of the DMFT index and OHIP-14 was significant only for the physical pain dimension (r = 0.16; P = 0.03). In DA subjects, correlations between the caries component (mean = 0.37) and all dimensions of OHIP-14 were statistically significant (P < 0.05). Conclusions: Despite the similarities in means in the DMFT index, the SiC Index and the caries-free percentage of subjects in both localities, access to dental treatment proved to be less effective for SA adolescents. Physical pain and psychological disability were the most frequent negative manifestations of impact on QoL. The SA adolescents were more negatively affected by dental caries in terms of QoL.

The filler content of the dental composite resins and their influence on different properties

The purpose of this study was to compare the inorganic content and morphology of one nanofilled and one nanohybrid composite with one universal microhybrid composite. The Vickers hardness, degree of conversion and scanning electron microscope of the materials light-cured using LED unit were also investigated. One nanofilled (Filtek (TM) Supreme XT), one nanohybrid (TPH (R) 3) and one universal microhybrid (Filtek (TM) Z-250) composite resins at color A2 were used in this study. The samples were made in a metallic mould (4 mm in diameter and 2 mm in thickness). Their filler weight content was measured by thermogravimetric analysis (TG). The morphology of the filler particles was determined using scanning electron microscope equipped with a field emission gun (SEM-FEG). Vickers hardness and degree of conversion using FT-IR spectroscopy were measured. Filtek (TM) Z-250 (microhybrid) composite resin shows higher degree of conversion and hardness than those of Filtek (TM) Supreme XT (nanofilled) and TPH (R) 3 (nanohybrid) composites, respectively. The TPH3 (R) (nanohybrid) composite exhibits by far the lowest mechanical property. Nanofilled composite resins show mechanical properties at least as good as those of universal hybrids and could thus be used for the same clinical indications as well as for anterior restorations due to their high aesthetic properties. Microsc. Res. Tech. 75:758765, 2012. (C) 2011 Wiley Periodicals, Inc

Contextual and individual inequalities in dental pain prevalence among Brazilian adults and elders

This study aimed to assess the prevalence of dental pain among adults and older people living in Brazil's State capitals. Information was gathered from the Telephone Survey Surveillance System for Risk and Protective Factors for Chronic Diseases (VIGITEL) in 2009 (n = 54,367). Dental pain was the outcome. Geographic region, age, gender, race, schooling, private health coverage, smoking, and soft drink consumption were the explanatory variables. Multilevel Poisson regression models were performed. Prevalence of dental pain was 15.2%; Macapa and Sao Luis had prevalence rates greater than 20%; all capitals in the South and Southeast, plus Cuiaba, Campo Grande, Maceio, Recife, and Natal had prevalence rates less than 15%. Factors associated with increased prevalence of dental pain were the North and Northeast regions, female gender, black/brown skin color, lack of private health insurance, smoking, and soft drink consumption. Dental pain is a public health problem that should be monitored by health surveillance systems.

Comparative clinical study of the effectiveness of different dental bleaching methods - two year follow-up

This study evaluated color change, stability, and tooth sensitivity in patients submitted to different bleaching techniques. Material and methods: In this study, 48 patients were divided into five groups. A half-mouth design was conducted to compare two in-office bleaching bleaching techniques (with and without light activation): G1: 35% hydrogen peroxide (HP) (Lase Peroxide - DMC Equipments, Sao Carlos, SP, Brazil) + hybrid light (HL) (LED/Diode Laser, Whitening Lase II DMC Equipments, Sao Carlos, SP, Brazil); G2: 35% HP; G3: 38% HP (X-traBoost - Ultradent, South Jordan UT, USA) + HL; G4: 38% HP; and G5: 15% carbamide peroxide (CP) (Opalescence PF - Ultradent, South Jordan UT, USA). For G1 and G3, HP was applied on the enamel surface for 3 consecutive applications activated by HL. Each application included 3x3' HL activations with 1' between each interval; for G2 and G4, HP was applied 3x15' with 15' between intervals; and for G5, 15% CP was applied for 120'/10 days at home. A spectrophotometer was used to measure color change before the treatment and after 24 h, 1 week, 1, 6, 12, 18 and 24 months. A VAS questionnaire was used to evaluate tooth sensitivity before the treatment, immediately following treatment, 24 h after and finally 1 week after. Results: Statistical analysis did not reveal any significant differences between in-office bleaching with or without HL activation related to effectiveness; nevertheless the time required was less with HL. Statistical differences were observed between the result after 24 h, 1 week and 1, 6, 12, 18 and 24 months (integroup). Immediately, in-office bleaching increased tooth sensitivity. The groups activated with HL required less application time with gel. Conclusion: All techniques and bleaching agents used were effective and demonstrated similar behaviors.

Measurement of buccal bone volume of dental implants by means of cone-beam computed tomography

Purpose: The aim of this study was to evaluate the accuracy of cone-beam computed tomography (CBCT) for measuring the buccal bone volume around dental implants. Materials and methods: Three to six implants were inserted into the anterior maxilla of eight skulls, depending on the availability of bone, and after this, the CBCT was performed. By means of CBCT image, measurements of the bone wall at three points of the implant were obtained, analyzed and compared with those obtained in the plaster skull casting. Results: The results showed that for the three points of the implants, no statistically significant difference in the measurements was obtained from the plaster model and CBCT images. Conclusions: CBCT can be a useful tool for assessing buccal bone volume along the implant. To cite this article:?Shiratori LN, Marotti J, Yamanouchi J, Chilvarquer I, Contin I, Tortamano-Neto P. Measurement of buccal bone volume of dental implants by means of cone-beam computed tomography.?Clin. Oral Impl. Res. 23, 2012; 797804.?doi: 10.1111/j.1600-0501.2011.02207.x

Influence of dental materials used for sealing caries lesions on laser fluorescence measurements

The aim of this study was to determine the influence of thickness and aging on the intrinsic fluorescence of sealing materials and their ability to block fluorescence from the underlying surface as assessed using a laser fluorescence device. Cavities of 0.5 mm and 1 mm depth were drilled into acrylic boards which were placed over two surfaces with different fluorescence properties: a low-fluorescence surface, to assess the intrinsic fluorescence of the sealing materials, and a high-fluorescence surface, to assess the fluorescence-blocking ability of the sealing materials. Ten cavities of each depth were filled with different sealing materials: Adper Scotchbond Multi-Purpose, Adper Single Bond 2, FluroShield, Conseal f and UltraSeal XT Plus. Fluorescence was measured with a DIAGNOdent pen at five different time points: empty cavity, after polymerization, and 1 day, 1 week and 1 month after filling. The individual values after polymerization, as well as the area under the curve for the different periods were submitted to ANOVA and the Tukey test (p < 0.05). At 0.5 mm, Scotchbond, FluroShield and UltraSeal showed insignificant changes in intrinsic fluorescence with aging and lower fluorescence after polymerization than Single Bond and Conseal. At 1 mm, Scotchbond and FluroShield showed the lowest intrinsic fluorescence, but only Scotchbond showed no chagnes in fluorescence with aging. At both depths, Scotchbond blocked significantly less fluorescence. All sealing materials blocked more fluorescence when applied to a depth of 1 mm. At 0.5 mm, fissure sealants blocked more fluorescence than adhesives, and did not show significant changes with aging. Scotchbond had the least affect on the fluorescence from the underlying surface and would probably have the least affect on the monitoring of sealed dental caries by laser fluorescence.

Private and Public Dental Care in the City of Sao Paulo in the First Decade of the XXI Century

Two concomitant movements occur in the first decade of the XXI century within the private and public dental services in Brazil: the entrance of oral health on the agenda of political priorities of the federal government and the vigorous growth of additional dental care. We analyzed the occurrence of these phenomena in the city of Sao Paulo, by seeking information in official documents and electronic databases in the Municipality of Sao Paulo, the Ministry of Health and National Health Agency (ANS), and also in scientific literature. During the studied period - January 2000 to December 2009 - and with basis on indicators such as coverage of First Consultation Program and Dental coverage Population Potential, percentages were found that characterize low public assistance and a situation far short of the constitutional principle of universal access to dental care. The growing number of beneficiaries of additional services through exclusively dental coverage insurance plans and other types of private insurance plans in the same period was significant, accounting for a major expansion of population coverage in this mode of care. It was found that, compared to the overall national framework, the city of Sao Paulo offers poor access to public dental care, with reduced supply of services to adults and aged people. Furthermore, considering the limitations of market additional services to provide dental care to all Brazilians, it reinforces the need for continuity and expansion of Brasil Sorridente, which is the programmatic expression of the National Oral Health Politics.

Salivary Cortisol, Alpha-Amylase and Heart Rate Variation in Response to Dental Treatment in Children

Objective. Anxiety and stress are usually related to the dental treatment situation. The objective was to investigate salivary cortisol and alpha-amylase levels (salivary biomarkers) and heart rate in children undergoing a minor dental procedure (dental prophylaxis). Study design. In total, 31 children (range 84-95 months) of both genders without caries or history of dental treatment/pain/trauma were selected. Three saliva samples were gathered: one prior to dental prophylaxis, one immediately after, and one ten minutes later Weight and height were assessed, and heart rate was evaluated prior to and during the procedure. Data were analyzed by correlation tests and t-test/Wikoxon (alpha=0.05). Results. Higher cortisol and amylase levels were observed before prophylaxis compared to afterward. Cortisol and amylase levels did not show a significant correlation, nor did salivary biomarkers and body mass index. However, heart rate and amylase levels showed a significant positive correlation. Conclusions. In the studied sample, certain anticipation of the dental treatment was observed because higher cortisol and amylase levels were observed before, rather than after, the event; moreover, a significant correlation between amylase levels and heart rate was observed. Thus, salivary biomarkers may be a valuable tool for evaluating anxiety-producing events, such as dental treatment, in children.

Cytogenetic instability of dental pulp stem cell lines

Human adult stem cells (hASCs) offer a potentially renewable source of cell types that are easily isolated and rapidly expanded for use in regenerative medicine and cell therapies without the complicating ethical problems that are associated with embryonic stem cells. However, the eventual therapeutic use of hASCs requires that these cells and their derivatives maintain their genomic stability. There is currently a lack of systematic studies that are aimed at characterising aberrant chromosomal changes in cultured ASCs over time. However, the presence of mosaicism and accumulation of karyotypic abnormalities within cultured cell subpopulations have been reported. To investigate cytogenetic integrity of cultured human dental stem cell (hDSC) lines, we analysed four expanded hDSC cultures using classical G banding and fluorescent in situ hybridisation (FISH) with X chromosome specific probe. Our preliminary results revealed that about 70% of the cells exhibited karyotypic abnormalities including polyploidy, aneuploidy and ring chromosomes. The heterogeneous spectrum of abnormalities indicates a high frequency of chromosomal mutations that continuously arise upon extended culture. These findings emphasise the need for the careful analysis of the cytogenetic stability of cultured hDSCs before they can be used in clinical therapies.