Effects of cobalt chloride on the stem cell marker expression and osteogenic differentiation of stem cells from human exfoliated deciduous teeth

Stem cells from human exfoliated deciduous teeth (SHEDs) are a promising source for tissue engineering and stem cell transplantation. However, long-term in vitro culture and expansion lead to the loss of stemness of SHEDs, compromising their therapeutic benefits. Hypoxia plays an essential role in controlling the stem cell behavior of mesenchymal stem cells (MSCs). Thus, this study aimed to investigate the effects of cobalt chloride (CoCl2), a hypoxia-mimetic agent, on the stem cell marker expression and osteogenic differentiation of SHEDs. SHEDs were cultured with or without 50 or 100 μM CoCl2. Their proliferation, apoptosis, stem cell marker expression, migration ability, and osteogenic differentiation were examined. Culture with 50 and 100 μM CoCl2 increased the hypoxia-inducible factor-1 alpha (HIF-1α) protein levels in a dose-dependent manner in SHEDs without inducing significant cytotoxicity. This effect was accompanied by an increase in the proportion of STRO-1+ cells. CoCl2 significantly increased the expression of stem cell markers (OCT4, NANOG, SOX2, and c-Myc) in a dose-dependent manner. The migration ability was also promoted by CoCl2 treatment. Furthermore, SHEDs cultured in osteogenic medium with CoCl2 showed a dose-dependent reduction in alkaline phosphatase (ALP) activity and calcium deposition. The expression of osteogenic-related genes was also suppressed by CoCl2, especially in the 100-μM CoCl2 group. In conclusion, CoCl2 increased the expression of stem cell markers and inhibited the osteogenic differentiation of SHEDs. These findings may provide evidence supporting the use of in vitro hypoxic environments mimicked by CoCl2 in assisting the clinical application of SHEDs.

Bacterial profile of the supragingival dental biofilm in children with deciduous and early mixed dentition using next generation sequencing (HOMINGS) technique

OBJECTIVE

Tdescribe the bacterial profile of the supragingival biofilm of children with temporary dentition (CTD) and early mixed dentition (CEMD), with the next-generation sequencing (HOMINGS) technique.

METHOD

A comparative descriptive study was carried out with 30 systemically healthy children aged between 5 and 7 years old from public schools in Cartagena-Colombia. All participants were caries-free applying the criteria of the International Caries Detection and Assessment System (ICDAS II) and had no caries experience according to the Decayed, Missing and Filled Teeth (DMFT) index. Supragingival biofilm samples were collected. Bacterial DNA was extracted and used for analysis using HOMINGS (Human Oral Microbe Identification using Next-Generation Sequencing) based on the sequencing of the V3-V4 region of the 16S rRNA gene using the Illumina MiSeq platform (V3-V4 primers).

RESULTS

A total of 360 species-specific and 65 genus-specific probes were identified. The bacterial genus most predominant in CTD were Streptococcus, Actinomyces, Veillonella and Fusobacterium (29.2% of all bacterial DNA present), while in CEMD the most predominant were Streptococcus, Leptotrichia, TM7 and Porphyromonas (24.5% of all bacterial DNA present). The bacterial species with the highest relative abundance in the oral biofilm microbiome from CTD were Streptococcus sanguinis, Rothia aeria, Gemella haemolysans, while in CEMD they were S. sanguinis, Leptotrichia spp. HOT-417 and Leptotrichia spp. HOT-498. The Shannon diversity index was 2.77 (SD=0.26) for CTD and 3.01 (SD=0.39) for CEMD (P=0.06).

CONCLUSIONS

The analysis of the bacterial profile of the supragingival dental biofilm in children with DMFT, by means of HOMINGS showed low microbiological diversity both in presence and in relative abundance in terms of genus as well as bacterial species.

Development of Jaw and Deciduous Teeth in Japanese Children -Comparing Size of Crown and Alveolar Area between Today and 40 Years Ago

The purpose of the present study was to investigate change in the size of the jaw and deciduous teeth in Japanese children over the past 40 years by performing measurements on plaster models of the dental arch obtained from children born between 2007 and 2009 (2000s group) and children born between 1968 and 1974 (70s) group. A total of 61 children were enrolled in the 2000s group, comprising 25 boys (average age, 4 years 5 months) and 36 girls (average age, 4 years 4 months), and 93 children in the 70s group, comprising 45 boys (4 years 6 months) and 48 girls (4 years 4 months). The mesiodistal width of the crown, dental arch width, dental arch length, dental arch height, and available arch length in these groups were measured using a 3D measurement system and the sums of the mesiodistal width of the crown and tooth size-arch length discrepancies calculated. The results of the two groups were statistically compared and the following conclusions reached: the size of deciduous teeth has not changed statistically over the last 40 years; the size of the dental arch has decreased in boys (p<0.01), while remaining approximately the same in girls; and the tooth size-arch length discrepancy has decreased, especially in boys (p<0.01). These results indicate that the interdental spaces of the deciduous dentition have decreased, increasing the risk of crowding in Japanese children.

Comparative evaluation of three obturation techniques in primary incisors using digital intra-oral receptor and C.B.C.T-an in vitro study

OBJECTIVES

Successful pulpectomy in primary teeth depends on quality of obturation. It can be evaluated using digital intra-oral receptor (D.I.O.R) and cone beam computed tomography (C.B.C.T). The purposes of this study were to compare 3 different obturation techniques such as lentulospiral, insulin syringe, and endodontic plugger in primary incisors and to evaluate its quality of obturation using D.I.O.R and C.B.C.T technique.

MATERIALS AND METHODS

Thirty-three extracted primary incisors were biomechanically prepared and obturated with zinc oxide eugenol cement by 3 different obturation techniques. The obturation was evaluated for length of obturation and voids using D.I.O.R and C.B.C.T methods.

RESULTS

There was a statistically significant difference between all the groups in length of obturation (P = 0.02) in both D.I.O.R and C.B.C.T. Significant differences (P = 0.03) were present in number of voids among 3 obturation techniques in C.B.C.T. Statistically more voids were observed with D.I.O.R in lentulospiral (P = 0.04) group and in insulin syringe (P = 0.02) group.

CONCLUSIONS

Acceptable result was obtained with lentulospiral in length of obturation compared to insulin syringe and endodontic plugger technique. Insulin syringe technique resulted in increased underfilling with least number of voids. More number of voids were seen in middle one-third and least number of voids were observed at apical one third of the root among all the 3 techniques of obturation. The study concluded that void identification is improved with D.I.O.R compared to C.B.C.T.

CLINICAL RELEVANCE

Lentulospiral reported effective length of obturation, while insulin syringe with least number of voids. D.I.O.R (2-Dimensional) is efficient in detecting voids compared to C.B.C.T (3-Dimensional) in obturated primary teeth.

Association of weight and height with timing of deciduous tooth emergence

OBJECTIVES

The aim of this study was to associate weight and height with the timing of deciduous tooth emergence.

METHODS

1756 children, aged from 1 to 33 months (755 females and 1001 males) had been previously examined for the timing of deciduous tooth emergence and their weights and heights measured. Children were categorized into weight and height groups (underweight, normal, overweight, short stature, normal and tall stature). Probit regression analysis was used to calculate the ages at emergence of each deciduous tooth. Tooth emergence ages were compared pairwise across the weight and height groups.

RESULTS

The deciduous dentition emerged between 7.9-31.5, 7.8-29.6 and 6.3-26.5 months in the underweight, normal and overweight children, respectively. In the height groups, the ranges were 9.0-31.3, 7.4-27.0 and 6.7-24.3 in the short, normal and tall children, respectively. The extremes of weight and height were related to the times at deciduous tooth emergence where a substantial increase in weight or height was associated with earlier emergence, and vice versa. However, only canines, lateral incisors and upper central incisor showed statistically significant association with weight and none of the teeth exhibited statistically significant association with height. Moreover, no emergence sequence change was associated with weight and height.

CONCLUSIONS

The present study provides the first weight and height- specific data on the timing of deciduous tooth emergence. Although both weight and height are generally associated with the timing of deciduous tooth emergence, weight shows a stronger association for canines, lateral incisors and upper central incisor. The findings will aid assessing normal emergence timing in children with variant weights and heights.

Clinical Evaluation of Quality of Obturation and Instrumentation Time using Two Modified Rotary File Systems with Manual Instrumentation in Primary Teeth

Introduction

Pulp therapy in primary teeth has been performed using various instrumentation techniques. However, the conventional instrumentation technique used for root canal preparation in primary teeth is hand instrumentation. Various Nickel-Titanium (Ni-Ti) instruments are available to perform efficient root canal preparation in primary teeth. These Ni-Ti instruments has been designed to aid in better root canal preparation in permanent teeth but are rarely used in primary teeth. It is necessary to assess the feasibility of using these adult rotary files with a modified sequence in primary teeth.

Aim

To compare the quality of obturation and instrumentation time during root canal preparation using hand files and modified rotary file systems in primary molars.

Materials and Methods

Forty-five primary mandibular molars were randomly assigned to three experimental groups (n=15). Group I was instrumented using k-hand files, Group II with S2 ProTaper universal file and Group III with 0.25 tip 4% taper K3 rotary file. Standardized digital radiographs were taken before and after root canal instrumentation. Root canal preparation time was also recorded. Statistical analysis of the obtained data was done using SPSS Software version 17.0. An intergroup comparison of the instrumentation time and the quality of obturation was done using ANOVA and Chi-square test with the level of significance set at 0.05.

Results

No significant differences were noted with regard to the quality of obturation (p=0.791). However, a statistically significant difference was noted in the instrumentation time between the three groups (p<0.05). ProTaper rotary system had significantly lesser instrumentation time when compared to that of K3 rotary system and hand file system.

Conclusion

The hand files, S2 ProTaper Universal and K3 0.25 tip 4% taper files systems performed similarly with respect to the quality of obturation. There was a significant difference in instrumentation time with manual instrumentation compared to the modified rotary file systems in primary teeth.

Polymorphism in the Eruption Sequence of Primary Dentition: A Cross-sectional Study

INTRODUCTION

Primary teeth have shown wide variations in their eruption time among different population. Population specific eruption ages are provided as mean with standard deviations or median ages with its percentile range. This alone will be insufficient for prediction of tooth eruption sequence because they provide no information on the frequency of sequence variation within the pairs of teeth. Norms of polymorphic variation in the eruption sequence can be more useful.

AIM

This study aims at providing norms for the sequence polymorphism in primary teeth among the children of Mysore population.

MATERIALS AND METHODS

A cross-sectional study was designed with 1392 children, recruited from December 2015 to June 2016 by simple random sampling method. Tooth was recorded as present or absent. Across the entire possible intra quadrant tooth pair, cases of present-present, absent-absent, present-absent and absent-present and were counted and computed as percentages.

RESULTS

Sequence polymorphisms were more common in 82-84 pairs of teeth. Significant polymorphic reverse sequence was observed in 52-54 (9%), 82-84 (35%) in males and 82-84 (18%) in females. There was no polymorphism in maxillary arch in females.

CONCLUSION

The present study provides the baseline data values for sequence variation in primary teeth eruption. To the best of investigators knowledge, there are no previous studies describing the sequence polymorphism in primary teeth in Indian population. The results of this study helps in assessment of eruption sequence problems in paediatric dentistry and in evaluation and prediction of tooth eruption sequence in individual child.

Developmental defects of enamel and dental caries in the primary dentition: A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis evaluated the association between developmental defects of enamel and dental caries in the primary dentition.

SOURCES

Electronic searches were performed in PubMed, Web of Knowledge, Scopus and Scielo for the identification of relevant studies.

STUDY SELECTION

Observational studies that examined the association between developmental defects of enamel and dental caries in the deciduous dentition were included. Additionally, meta-analysis, funnel plots and sensitivity analysis were employed to synthesize the available evidence. Multivariable meta-regression analysis was performed to explore heterogeneity among studies.

DATA

A total of 318 articles were identified in the electronic searches. Of those, 16 studies were included in the meta-analysis. Pooled estimates revealed that children with developmental defects of enamel had higher odds of having dental caries (OR 3.32; 95%CI 2.41-4.57), with high heterogeneity between studies (I² 80%). Methodological characteristic of the studies, such as where it was conducted, the examined teeth and the quality of the study explained about 30% of the variability. Concerning type of defect, children with hypoplasia and diffuse opacities had higher odds of having dental caries (OR 4.28; 95%CI 2.24-8.15; OR1.42; 95%CI 1.15-1.76, respectively).

CONCLUSIONS

This systematic review and meta-analysis demonstrates a clear association between developmental defects of enamel and dental caries in the primary dentition.

Mesial Stripping of Mandibular Deciduous Canines for Correction of Permanent Lateral Incisors

AIM

Stripping is a technique of creating space for correction of crowding by interproximal enamel reduction. This study sought to assess the efficacy of mesial stripping of mandibu-lar deciduous canines for correction of rotated and lingually erupted lateral incisors.

MATERIALS AND METHODS

This clinical trial was performed on 42 patients with <3 mm mandibular anterior crowding. The required space was determined using the Moyers' method and 3 mm of canine mesial surfaces was removed using a bur. Alginate impressions were made and the correction of crowding was evaluated until 5 months after the treatment. Data were analyzed using Fisher's exact, Kruskal-Wallis, and Mann-Whitney U tests.

RESULTS

Mesial stripping of canines completely removed the crowding of anterior teeth; however; in a few cases, this correction was not complete, in which, the amount of space required was calculated to be near zero. Patient gender and occlusal relations had no significant effect on the correction of crowding; however, the amount of space required was significantly affected by the position of left lateral incisors (p < 0.001).

CONCLUSION

Mesial stripping of deciduous canines is an effective technique to remove <3 mm crowding of buccally and lingually erupted permanent lateral incisors. Thus, stripping is recommended for space regaining and crowding correction.

HOW TO CITE THIS ARTICLE

Nakhjavani YB, Nakhjavani FB, Jafari A. Mesial Stripping of Mandibular Deciduous Canines for Correction of Permanent Lateral Incisors. Int J Clin Pediatr Dent 2017;10(3):229-233.

Comparative analysis of secretory factors from permanent- and deciduous-teeth periodontal ligament cells

OBJECTIVE

Studies of regenerative therapies have focused on the paracrine effects of mesenchymal stem cells, but little has been revealed about the humoral factors of periodontal ligament (PDL) stem cells. The aim of this study was to identify and compare the secretory factors of human permanent- and deciduous-teeth PDL cells (P-PDL and D-PDL cells, respectively) in order to understand the characteristics of these cells and their potential applications in regenerative therapies.

DESIGN

Conditioned media were collected from P-PDL and D-PDL cells (P-PDL-CM and D-PDL-CM, respectively). These media were analyzed with high-performance liquid-chromatography-coupled electrospray ionization tandem mass spectrometry and a cytokine membrane assay. In addition, Western blot analysis was performed to verify the differences between the two media.

RESULTS

Cytokines related to neurogenesis (NT-3 and NT-4) and angiogenesis-related cytokines (EGF and IGF-1) were identified in P-PDL-CM. The expression levels of immune-response-related cytokines (interleukins I, II, and IV) and secreted proteins related to tissue degradation and catalytic activities (matrix metallopeptidase 1 (MMP1), Proteasome subunit, alpha type, 1 (PSMA1), and cullin 7 (CUL7)) were higher in D-PDL-CM. Vasorin (VASN) was expressed more strongly in P-PDL-CM, but tudor domain containing 7 (TDRD7) was expressed more strongly in D-PDL-CM in Western blot analysis.

CONCLUSION

The cytokine expressions of the two cell types showed different patterns, especially in neurogenesis and immune responses. P-PDL cells are more suitable candidates for applications in regenerative therapies.

Prenatal metal exposure in the Middle East: imprint of war in deciduous teeth of children

In war zones, the explosion of bombs, bullets, and other ammunition releases multiple neurotoxicants into the environment. The Middle East is currently the site of heavy environmental disruption by massive bombardments. A very large number of US military bases, which release highly toxic environmental contaminants, have also been erected since 2003. Current knowledge supports the hypothesis that war-created pollution is a major cause of rising birth defects and cancers in Iraq. We created elemental bio-imaging of trace elements in deciduous teeth of children with birth defects from Iraq. Healthy and naturally shed teeth from Lebanon and Iran were also analyzed for trace elements. Lead (Pb) was highest in teeth from children with birth defects who donated their teeth from Basra, Iraq (mean 0.73-16.74 (208)Pb/(43)Ca ppm, n = 3). Pb in healthy Lebanese and Iranian teeth were 0.038-0.382 (208)Pb/(43)Ca ppm (n = 4) and 0.041-0.31 (208)Pb/(43)Ca ppm (n = 2), respectively. Our hypothesis that increased war activity coincides with increased metal levels in deciduous teeth is confirmed by this research. Lead levels were similar in Lebanese and Iranian deciduous teeth. Deciduous teeth from Iraqi children with birth defects had remarkably higher levels of Pb. Two Iraqi teeth had four times more Pb, and one tooth had as much as 50 times more Pb than samples from Lebanon and Iran.

Survival of Composite Resin Restorations of severely Decayed Primary Anterior Teeth retained by Glass Fiber Posts or Reversed-orientated Metal Posts

Aim: The aim of this study was to compare the survival of composite resin restorations retained by glass fiber posts or reversed-orientated (upside-down) metal posts in severely decayed primary anterior teeth after 6, 12, and 18 months.

Materials and methods: A total of forty-four 3- to 5-year-old children with bilateral severely decayed primary maxillary canines were included. Patients were treated under general anesthesia. After pulpectomy, an intracanal post was seated in the primary maxillary canine on each side: either a glass fiber post or a metallic post in reversed orientation and teeth restored with light-cured composite. Survival rate of each technique was evaluated at predetermined follow-ups and data were analyzed with McNemar’s test (α = 0.05).

Results: The difference in survival of restorations retained by two types of posts was not statistically significant in clinical and radiographical evaluations after 6, 12, and 18 months. The survival rate of reversed-orientated metal and glass fiber posts after 18 months was 81.1 and 67.6% respectively (p = 0.14).

Conclusion: Reversed-orientated metal post did not show lower clinical survival compared with glass fiber posts in 18-month follow-up. Hence, reversed-orientated metal post can be considered as a potential method to obtain retention for composite restorations in severely decayed primary anterior teeth.

How to cite this article: Vafaei A, Ranjkesh B, L0vschall H, Erfanparast L, Jafarabadi MA, Oskouei SG, Isidor F. Survival of Composite Resin Restorations of severely Decayed Primary Anterior Teeth retained by Glass Fiber Posts or Reversed-orientated Metal Posts. Int J Clin Pediatr Dent 2016;9(2):109-113.

Role of inflammation in developmental odontogenic pathosis

Periapical infection in the primary tooth may lead to periapical abscess, granuloma, radicular cyst and even osteomyelitis. The infection in primary teeth can also affect the developing successor teeth leading to hypomineralization, hypoplasia, arrest of tooth development, regional odontodysplasia, delayed eruption etc. The purpose of this article is to report a case of malformed permanent tooth in relation to overlying infected deciduous teeth. The probable role of inflammation in pathogenesis of the present condition is also being discussed.

In vitro investigation of the cleaning efficacy, shaping ability, preparation time and file deformation of continuous rotary, reciprocating rotary and manual instrumentations in primary molars

Background. Efficient canal preparation is the key to successful root canal treatment. This study aimed to assess the cleaning and shaping ability, preparation time and file deformation of rotary, reciprocating and manual instrumentation in canal preparation of primary molars.

Methods. The mesiobuccal canals of 64 extracted primary mandibular second molars were injected with India ink. The samples were randomly divided into one control and three experimental groups. Experimental groups were instrumented with K-file, Mtwo in continuous rotation and Reciproc in reciprocating motion, respectively. The control group received no treatment. The files were discarded after four applications. Shaping ability was evaluated using CBCT. After clearing, ink removal was scored. Preparation time and file fracture or deformation was also recorded. Data were analyzed with SPSS 19 using chi-squared, Fisher’s exact test, Kruskal-Wallis and post hoc tests at a significance level of 0.05.

Results. Considering cleanliness, at coronal third Reciproc was better than K-file (P < 0.001), but not more effective than Mtwo (P = 0.080). Furthermore, Mtwo leaved the canal cleaner than K-file (P = 0.001). In the middle third, only Reciproc exhibited better cleaning efficacy than K-file (P = 0.005). In the apical third, no difference was detected between the groups (P = 0.794). Regarding shaping ability, no differences were found between Reciproc and Mtwo (P = 1.00). Meanwhile, both displayed better shaping efficacy than K-file (P < 0.05). Between each two groups, there were differences in preparation time (P < 0.05), with Reciproc being the fastest. No file failure occurred.

Conclusion. Fast and sufficient cleaning and shaping could be achieved with Mtwo and especially with Reciproc.

Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth

We report progress in using the isotopic composition and concentration of Pb in the dentine and enamel of deciduous teeth to provide a high resolution time frame of exposure to Pb during fetal development and early childhood. Isotope measurements (total Pb and (208)Pb/(206)Pb, (207)Pb/(206)Pb ratios) were acquired by laser ablation inductively coupled mass spectrometry at contiguous 100 micron intervals across thin sections of the teeth; from the outer enamel surface to the pulp cavity. Teeth samples (n=10) were selected from two cohorts of children, aged 5-8 years, living in NE England. By integrating the isotope data with histological analysis of the teeth, using the daily incremental lines in dentine, we were able to assign true estimated ages to each ablation point (first 2-3 years for molars, first 1-2 years for incisors+pre-natal growth). Significant differences were observed in the isotope composition and concentration of Pb between children, reflecting differences in the timing and sources of exposure during early childhood. Those born in 2000, after the withdrawal of leaded petrol in 1999, have the lowest dentine Pb levels (<0.2µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.126-2.079) (208)Pb/(206)Pb (mean ±2σ: 0.879-0.856) ratios that correlate very closely with modern day Western European industrial aerosols (PM10, PM2.5) suggesting that diffuse airborne pollution was probably the primary source and exposure pathway. Legacy lead, if present, is insignificant. For those born in 1997, dentine lead levels are typically higher (>0.4µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.145-2.117) (208)Pb/(206)Pb (mean ±2σ: 0.898-0.882) ratios that can be modelled as a binary mix between industrial aerosols and leaded petrol emissions. Short duration, high intensity exposure events (1-2 months) were readily identified, together with evidence that dentine provides a good proxy for childhood changes in the isotope composition of blood Pb. Our pilot study confirms that laser ablation Pb isotope analysis of deciduous teeth, when carried out in conjunction with histological analysis, permits a reconstruction of the timing, duration and source of exposure to Pb during early childhood. With further development, this approach has the potential to study larger cohorts and appraise environments where the levels of exposure to Pb are much higher.

New phiomorph rodents from the latest Eocene of Egypt, and the impact of Bayesian "clock"-based phylogenetic methods on estimates of basal hystricognath relationships and biochronology

The Fayum Depression of Egypt has yielded fossils of hystricognathous rodents from multiple Eocene and Oligocene horizons that range in age from ∼37 to ∼30 Ma and document several phases in the early evolution of crown Hystricognathi and one of its major subclades, Phiomorpha. Here we describe two new genera and species of basal phiomorphs, Birkamys korai and Mubhammys vadumensis, based on rostra and maxillary and mandibular remains from the terminal Eocene (∼34 Ma) Fayum Locality 41 (L-41). Birkamys is the smallest known Paleogene hystricognath, has very simple molars, and, like derived Oligocene-to-Recent phiomorphs (but unlike contemporaneous and older taxa) apparently retained dP(4)∕4 late into life, with no evidence for P(4)∕4 eruption or formation. Mubhammys is very similar in dental morphology to Birkamys, and also shows no evidence for P(4)∕4 formation or eruption, but is considerably larger. Though parsimony analysis with all characters equally weighted places Birkamys and Mubhammys as sister taxa of extant Thryonomys to the exclusion of much younger relatives of that genus, all other methods (standard Bayesian inference, Bayesian "tip-dating," and parsimony analysis with scaled transitions between "fixed" and polymorphic states) place these species in more basal positions within Hystricognathi, as sister taxa of Oligocene-to-Recent phiomorphs. We also employ tip-dating as a means for estimating the ages of early hystricognath-bearing localities, many of which are not well-constrained by geological, geochronological, or biostratigraphic evidence. By simultaneously taking into account phylogeny, evolutionary rates, and uniform priors that appropriately encompass the range of possible ages for fossil localities, dating of tips in this Bayesian framework allows paleontologists to move beyond vague and assumption-laden "stage of evolution" arguments in biochronology to provide relatively rigorous age assessments of poorly-constrained faunas. This approach should become increasingly robust as estimates are combined from multiple independent analyses of distantly related clades, and is broadly applicable across the tree of life; as such it is deserving of paleontologists' close attention. Notably, in the example provided here, hystricognathous rodents from Libya and Namibia that are controversially considered to be of middle Eocene age are instead estimated to be of late Eocene and late Oligocene age, respectively. Finally, we reconstruct the evolution of first lower molar size among Paleogene African hystricognaths using a Bayesian approach; the results of this analysis reconstruct a rapid latest Eocene dwarfing event along the lineage leading to Birkamys.

Characteristics of stem cells from human exfoliated deciduous teeth (SHED) from intact cryopreserved deciduous teeth

The aim of this study is to compare the characteristics of stem cells derived from human exfoliated deciduous teeth (SHED) from cryopreserved intact deciduous teeth with those of fresh SHED. In total, 20 exfoliated deciduous teeth were randomly divided into a fresh group (f-SHED; n = 11) and cryopreserved group (c-SHED; n = 9; stored for 1-8 months). Following thawing and separation of the pulp, the SHED cells were cultured, and the characteristics as mesenchymal stem cells were investigated using proliferation assays, cell-cycle analysis, colony-forming unit-fibroblast (CFU-F) assays, and flow cytometry analyses. Furthermore, differentiation into adipogenic and osteogenic lineages was investigated in vitro as well as in vivo via transplantation in mice. We found no significant differences between the two groups in the proliferation analyses, in the expression of mesenchymal stem cell markers, or in the adipogenic and osteogenic differentiation in vitro (p < 0.05). Furthermore, the in vivo transplantation results showed no significant differences in the quantity of bone tissue that formed or in histochemistry performance (p < 0.05). In conclusion, cryopreservation of intact exfoliated deciduous teeth appears to be a useful method for preserving SHED.

Evaluation of the Efficacy of Caries Removal Using Polymer Bur, Stainless Steel Bur, Carisolv, Papacarie - An Invitro Comparative Study

CONTEXT

Dental caries continues to affect a significant portion of the world population and treatment of the decay is associated with pain by many patients. Intervention and application of rotary instruments for treatment of carious lesions has often resulted in considerable removal of tooth structure. Chemo-mechanical method, a minimal invasive technique for caries removal was developed to overcome these shortcomings. This innovative method seems to be efficient in removing infected dentine without altering the healthy dental tissue or harming the adjacent oral mucosa.

AIM

To evaluate the efficacy and efficiency of Caries removal Using Polymer Bur, Stainless Steel Bur, Carisolv and Papacarie.

MATERIALS AND METHODS

A total of 120 sectioned specimens were obtained from 60 extracted teeth. Each tooth was sectioned mesiodistally in the center of the carious lesion so that two halves (buccal and lingual or palatal) having equal sized carious lesions are compared. The sectioned specimens were subdivided into four groups (Polymer Bur, Stainless Steel Bur, Carisolv, Papacarie) allotting 30 specimens to each for caries excavation.

RESULTS

One-way ANOVA, Chi-square test analysis was done for comparison between groups which showed significant results with Stainless Steel Bur excavation taking less mean time when compared to other agents and Polymer Bur showed more amount of bacterial remnants after excavation whereas Carisolv and Papacarie were efficient with less dentinal tubule destruction and bacterial remnants after excavation. Further inter comparison between groups was done using Paired t-test and Fischer's Exact-test.

CONCLUSION

The Mean time taken by Stainless Steel Bur excavation was found to be less and caused more amount of dentinal tubule destruction when compared to Polymer Bur, Carisolv and Papacarie. Chemo-mechanical methods found to be more efficient with lesser amount of bacterial remnants and dentinal tubule destruction after caries excavation when compared to conventional methods.

Evaluation of the effect of using electrosurgery in pulpectomy of deciduous teeth on succedaneous teeth: an animal study

OBJECTIVES

The aim of this study was to determine the probable side effects of electrosurgery in pulpectomy of deciduous teeth on succedaneous teeth in dogs.

MATERIALS AND METHODS

In this animal study, all maxillary and mandibular teeth at one side of five puppies' mouths were treated employing electrosurgical pulpectomy and were then compared with those of the other side treated using the conventional method. The electrosurgical dental electrode was placed in canals to the point of working length for the experimental group. After pulpectomy, the canals were filled with zinc oxide eugenol paste and the access cavity was restored with amalgam. The dogs remained under care until their successor teeth erupted and clinical examination was performed.

RESULTS

The teeth treated employing electrosurgical pulpectomy presented natural appearance with no observable defects including enamel hypoplasia, diffuse opacities of enamel, demarcated opacities, and enamel discoloration.

CONCLUSION

Electrosurgical pulpectomy can be considered as an option for pulpectomy of deciduous teeth.

T. S, Bhuyan R, Bhuyan SK. Non syndromic familial bilateral decidious taurodontism - a first case report

Taurodontism is anatomical and morphological alteration in the shape of the tooth. In taurodontism the crowns appear larger and the roots shorter compared to the normal anatomy of the respective tooth. The incidence of taurodontism in deciduous is very low and is also not very common in permanent dentition. The endodontic treatment protocol of taurodontic tooth is challenging. Taurodontic tooth requires a very cautious approach in identifying the root canal orientation and presence of any extra or lateral canals.

Analysis of tooth mortality among nigerian children in a tertiary hospital setting

Background:

Tooth mortality is important in evaluating dental care as tooth loss is a reflection of cumulative effects of past disease and treatment practices.

Aim:

The aim of this study is to analyze the pattern of tooth mortality among pediatric dental patients treated at the University of Benin Teaching Hospital, Benin City, Nigeria.

Subjects and Methods:

This was a retrospective study of patients treated at the Pediatric dental clinic of the University of Benin Teaching Hospital, Benin City between June 2007 and April 2012. Patients’ age, sex, indication for extraction and type of tooth were reviewed. Data analysis in the form of frequency, percentages, cross tabulation, Chi-square statistics were performed using the statistical package for the social sciences (SPSS) (Chicago IL, USA) version 17.0.

Results:

A total of 712 patients between the ages 0 and 16 years were seen and 1039 extractions were performed. Tooth extraction was performed more among females 53.4% (380/712) and those aged 6-12 years 54.1% (384/712). About one-third 33.1% (236/712) of the patients had two or more teeth extraction. The deciduous teeth were more frequently extracted 65.2% (677/1039) with second molars being the most frequently extracted deciduous teeth and first molars being the most frequently extracted permanent teeth. Permanent third molar accounted for the 0.7% (7/1039) of the extracted teeth in this study. The extractions were done more on the lower arch and on the right side of the mouth. In this study, dental caries was the leading reason for extraction of the deciduous and permanent teeth. Neonatal teeth and supernumerary accounted for 0.9% (4/438) and 0.7% (2/289) of deciduous and permanent dentition extractions respectively.

Conclusion:

Dental caries was the leading reason for extraction in both deciduous and permanent dentitions with female patients aged 6-12 years receiving the most tooth/teeth extractions. Stakeholder in child health need to pay adequate attention to dental caries preventive approaches to enable the pediatric population reach adulthood with a healthier dentition.

Effects of cryopreservation on the characteristics of dental pulp stem cells of intact deciduous teeth

OBJECTIVES

The aim of this study was to isolate and cultivate cells from the pulp of 7-day-cryopreserved intact deciduous human teeth and evaluate the effect of cryopreservation on dental pulp stem cell (DPSC) characteristics.

DESIGN

Twenty-six deciduous teeth were collected and allocated in two groups: immediate cell isolation (non-cryopreserved group) and intact cryopreserved (cryopreserved group). The teeth were cryopreserved in dimethylsulfoxide solution and recovered after 7 days. The success rate of isolation, proliferation, surface markers (CD14, CD29, CD34, CD45, CD73, CD90, and HLA-DR), differentiation capacity, and morphology were evaluated.

RESULTS

Isolation success rate was 61% and 30% for the non-cryopreserved and cryopreserved groups, respectively. There were no statistical differences between the groups for the tested surface markers. The cells in both groups were capable of differentiating into three mesenchymal lineages. No statistical differences between the groups were observed through the time course proliferation assay (0, 1, 3, 5, and 7 days); however, the mean time between isolation and the fifth passage was shorter for the non-cryopreserved group (p=0.035). The morphology of the cells was considered altered in the cryopreserved group.

CONCLUSION

DPSCs were obtained from cryopreserved intact deciduous teeth without changes in the immunophenotypical characteristics and differentiation ability; however, lower culture rates, proliferation potential, and morphological alterations were observed in relation to the control group.

A changing trend in eruption age and pattern of first deciduous tooth: correlation to feeding pattern

BACKGROUND

Feeding mode during infancy and its effect on deciduous tooth appearance in oral cavity in two generations and among genders.

AIM AND OBJECTIVE

Study aimed to compare and correlate times and patterns of deciduous tooth eruption in breastfeeding (OBF), partial breastfeeding (PBF) and spoon feeding (SF) infants and initiation of semisolid food feeding (SSF) in infants. It also aimed to address the variations in the time of eruption of first deciduous tooth and its pattern in two generations who had more than a decade of difference in ages.

MATERIALS AND METHODS

An open-ended questionnaire study was conducted on mothers of 265 patients from two groups, generation 1 (G1)- adults who were aged 20-35 years and second group, generation 2 (G2) - children who were below 5 years of age .

RESULTS

A statistical significance was observed with respect to age, gender, generations, and frequency of breastfeeding, partial breastfeeding and time of initiation of semisolid food.

CONCLUSION

There is a delayed eruption of teeth in present generation. For girls, it occurs at age of 7.88 months and for boys, it occurs at the age of 8.08 months.

An in-vitro assessment of the shear bond strength of bulk-fill resin composites to permanent and deciduous teeth

OBJECTIVES

This study aimed to evaluate the shear bond strength (SBS) of bulk-fill resin composites (RCs) to deciduous and permanent teeth.

METHODS

The following parameters were investigated: (1) tooth type (deciduous and permanent), (2) tooth substrate (enamel and dentine), (3) restorative material (a high- and a low-viscosity bulk-fill RC and a regular nanohybrid RC as control), and (4) adhesive (two self-etching adhesives). The combination of those parameters resulted in a total of 24 different groups (n=20). Permanent caries-free human molars (240) and deciduous teeth (240) were selected. The bulk-fill RCs (Tetric Evo Ceram Bulk Fill and SureFil SDR) were applied in one 4-mm increment, whereas the regular RC (Tetric Evo Ceram) was layered in two consecutive 2-mm increments. The SBS was examined after storing the specimens for 24 h at 37 °C in distilled water, followed by thermal ageing (5000 cycles between 5 °C and 55 °C).

RESULTS

Data were statistically analyzed using one- and multiway analyses of variance and an independent-samples t-test (α=0.05). The multivariate analysis (general linear model with partial eta-squared statistics) tested the influence of the parameters tooth type, tooth substrate, restorative material, and adhesive on the SBS. The parameter tooth type showed no significant impact on the SBS (p=0.576). The influence of the other parameters was significant (p<0.05) but low, and the highest influence was exerted by the parameter adhesive (η(P)(2)=0.120, p=0.0001) followed by tooth substrate (η(P)(2)=0.092, p=0.0001) and restorative material (η(P)(2)=0.028, p=0.0001). The fracture pattern was predominantly adhesive (61.9%) or mixed (38.1), and no cohesive or prefailure was registered.

CONCLUSIONS

Bulk-fill materials performed comparable or better than the nanohybrid RC used as control, but the adhesive used was the most relevant factor of influence. This material type might be clinically an option for a faster restoration in both permanent and deciduous teeth.

CLINICAL SIGNIFICANCE

Bulk-fill materials performed comparable or slightly better than the nanohybrid RC used as control. Clinically, flowable bulk-fill RCs might be an advantage in restoring deep, narrow cavities, with difficult access angles, whereas larger cavities might be restored easily and faster using high-viscosity compounds.