Dental caries in the fossil record: a window to the evolution of dietary plasticity in an extinct bear.

During the late Pleistocene of North America (≈36,000 to 10,000 years ago), saber-toothed cats, American lions, dire wolves, and coyotes competed for prey resources at Rancho La Brea (RLB). Despite the fact that the giant short-faced bear (Arctodus simus) was the largest land carnivoran present in the fauna, there is no evidence that it competed with these other carnivores for prey at the site. Here, for the first time, we report carious lesions preserved in specimens of A. simus, recovered from RLB. Our results suggest that the population of A. simus from RLB was more omnivorous than the highly carnivorous populations from the Northwest. This dietary variation may be a consequence of different competitive pressures.

Cytotoxic effect of the debris apically extruded during three different retreatment procedures.

We evaluated the cytotoxic effects of the debris apically extruded during root canal retreatment on primary human osteoblast (HOb) cells in vitro. TNF-α and IL-1ß levels were also measured. We examined three different techniques: conventional hand-files, and Mtwo and Reciproc retreatments. Filled mandibular incisors were prepared for a cytotoxicity assay in an experimental root model. The material was divided into three groups according to the technique used. Ten teeth were used as control. HOb cells were exposed to the extruded content and cytotoxicity was evaluated using the MTT test (assessing cell metabolic activity). TNF-α and IL-1ß production was also analyzed using enzyme-linked immunosorbent assay. Then, all the teeth were radiographed and the residual filling material was quantified. Data were subjected to analysis of variance (ANOVA) and Tukey's test (P < 0.05). The conventional hand-file technique was significantly more cytotoxic than the other methods (P < 0.05). Reciproc was less cytotoxic than Mtwo retreatment (P < 0.05). All endodontic retreatment techniques led to a significant upregulation of IL-1ß levels (P < 0.05). However, only the conventional hand-file technique caused a significant increase in TNF-α levels (P < 0.05). Root-filling removal did not affect the levels of these proteins (P > 0.05). The Reciproc system required less time than the other two methods to remove the root-filling materials (P < 0.01). The endodontic retreatment with Reciproc was the least cytotoxic and the least time-consuming method of gutta-percha and sealer removal. (J Oral Sci 58, 211-217, 2016).

Genome Sequencing and Transposon Mutagenesis of Burkholderia seminalis TC3.4.2R3 Identify Genes Contributing to Suppression of Orchid Necrosis Caused by B. gladioli.

From a screen of 36 plant-associated strains of Burkholderia spp., we identified 24 strains that suppressed leaf and pseudobulb necrosis of orchid caused by B. gladioli. To gain insights into the mechanisms of disease suppression, we generated a draft genome sequence from one suppressive strain, TC3.4.2R3. The genome is an estimated 7.67 megabases in size, with three replicons, two chromosomes, and the plasmid pC3. Using a combination of multilocus sequence analysis and phylogenomics, we identified TC3.4.2R3 as B. seminalis, a species within the Burkholderia cepacia complex that includes opportunistic human pathogens and environmental strains. We generated and screened a library of 3,840 transposon mutants of strain TC3.4.2R3 on orchid leaves to identify genes contributing to plant disease suppression. Twelve mutants deficient in suppression of leaf necrosis were selected and the transposon insertions were mapped to eight loci. One gene is in a wcb cluster that is related to synthesis of extracellular polysaccharide, a key determinant in bacterial-host interactions in other systems, and the other seven are highly conserved among Burkholderia spp. The fundamental information developed in this study will serve as a resource for future research aiming to identify mechanisms contributing to biological control.

Cytotoxicity and gelatinolytic activity of a new silicon-based endodontic sealer.

PURPOSE: To compare the cytotoxicity, gelatinolytic activity, and protein levels (MMP-2 and MMP-9) produced by 3T3 fibroblasts cells after stimulation with GuttaFlow 2 and AH Plus. METHODS: 3T3 fibroblasts were incubated with elutes of GuttaFlow 2 and AH Plus for 24 h. The cytotoxicity of tested materials was determined using the MTT and the LDH assay. Supernatants of cell cultures incubated with sealers were collected to determine the levels of MMP-2 and MMP-9 gelatinolytic activity by gelatin zymography. Cell lysates were used to determine MMP-2 and MMP-9 protein levels by Western Blot. Data were analyzed using ANOVA and Tukey test (P<0.05). RESULTS: AH Plus showed significantly less cell viability (mitochondrial activity of cells) than GuttaFlow 2 (P<0.01). Moreover, GuttaFlow 2 was noncytotoxic, showing no statistically significant difference in LDH leakage levels compared to the control group (P>0.05). Specific characterization of MMPs demonstrated that GuttaFlow 2 seemed not to affect MMP-2 levels compared with the control group, while AH Plus had elevated gelatinolytic activity and protein levels of MMP-2 as confirmed by quantitative measurements. No detectable gelatinolytic activity or protein levels of MMP-9 (92 kDa) was observed in any tested group. CONCLUSIONS: GuttaFlow 2 did not showed cytotoxic effects and did not induce MMP-2 or MMP-9 expression.

Caries-removal effectiveness of a papain-based chemo-mechanical agent: A quantitative micro-CT study.

The aim of this study was to access the effectiveness and specificity of a papain-based chemo-mechanical caries-removal agent in providing minimum residual caries after cavity preparation. In order to do it, extracted carious molars were selected and scanned in a micro-CT before and after caries-removal procedures with the papain-based gel. Similar parameters for acquisition and reconstruction of the image stacks were used between the scans. After classification of the dentin substrate based on mineral density intervals and establishment of a carious tissue threshold, volumetric parameters related to effectiveness (mineral density of removed dentin volume and residual dentin tissue) and specificity (relation between carious dentin in removed volume and initial caries) of this caries-removal agent were obtained. In general, removed dentin volume was similar or higher than the initial carious volume, indicating that the method was able to effectively remove dentin tissue. Samples with an almost perfect accuracy in carious dentin removal also showed an increased removal of caries-affected tissue. On the contrary, less or no affected dentin was removed in samples where some carious tissue was left in residual dentin. Mineral density values in residual dentin were always higher or similar to the threshold for mineral density values in carious dentin. In conclusion, the papain-based gel was effective in removing carious dentin up to a conservative in vitro threshold. Lesion characteristics, such as activity and morphology of enamel lesion, may also influence caries-removal properties of the method.

Reciprocating versus rotary systems for root filling removal: assessment of the apically extruded material.

INTRODUCTION: This study was designed to quantitatively evaluate the amount of apically extruded debris by comparing the ProTaper Universal Retreatment system (Dentsply Maillefer, Ballaigues, Switzerland) with 2 reciprocating single-file systems (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer]) during endodontic retreatment. METHODS: Forty-five mandibular premolars with a single canal were prepared with the ProTaper Universal system and then obturated. The specimens were divided into 3 groups (n = 15) according to the system used for filling removal: ProTaper Universal Retreatment system associated with the ProTaper Universal system (until file F4 40/0.06]), Reciproc system (Reciproc R40 [40/0.06]), and WaveOne system (WaveOne Large [40/0.08]). Sodium hypochlorite was used as an irrigant, and the apically extruded debris was collected in glass vials and then dried. The mean weight of debris was assessed with a microbalance and statistically analyzed using 1-way analysis of variance and post hoc Tukey multiple comparison tests (P < .05). RESULTS: The ProTaper Universal Retreatment system produced significantly more debris compared with the Reciproc and WaveOne systems (P < .01). The reciprocating systems showed no significant difference between them (P > .05). CONCLUSIONS: Under the conditions of the present study, all systems caused apical debris extrusion. Reciprocating systems were associated with less debris extrusion when compared with a conventional rotary retreatment system.

Effective use of a horizontally-transferred pathway for dichloromethane catabolism requires post-transfer refinement.

When microbes acquire new abilities through horizontal gene transfer, the genes and pathways must function under conditions with which they did not coevolve. If newly-acquired genes burden the host, their utility will depend on further evolutionary refinement of the recombinant strain. We used laboratory evolution to recapitulate this process of transfer and refinement, demonstrating that effective use of an introduced dichloromethane degradation pathway required one of several mutations to the bacterial host that are predicted to increase chloride efflux. We then used this knowledge to identify parallel, beneficial mutations that independently evolved in two natural dichloromethane-degrading strains. Finally, we constructed a synthetic mobile genetic element carrying both the degradation pathway and a chloride exporter, which preempted the adaptive process and directly enabled effective dichloromethane degradation across diverse Methylobacterium environmental isolates. Our results demonstrate the importance of post-transfer refinement in horizontal gene transfer, with potential applications in bioremediation and synthetic biology.

Assessment of coronal leakage of a new temporary light-curing filling material in endodontically treated teeth.

INTRODUCTION: The aim of this study was to evaluate the sealing ability of a new temporary filling material X-Temp LC (DFL, São Paulo, SP, Brazil) compared with that obtained for Coltosol (Vigodent, Rio de Janeiro, RJ, Brazil) and Vitro Fill (DFL, Rio de Janeiro, RJ, Brazil), using a dye penetration test. METHODS: Standard endodontic access cavities were prepared in 75 human premolars. The teeth were divided into five groups (n = 15 for each group), including a positive (no sealing of access cavity) and a negative control (Filtek Z350 XT, 3M, São Paulo, SP, Brazil). In the experimental groups, the access cavities were sealed with one of the three tested materials. After that, the teeth were immersed in 10% Indian ink for 14 days. The teeth were then rinsed, dried, sectioned in bucco-lingual direction and evaluated under a stereomicroscope using scores for dye penetration. Data were analyzed using Kruskall-Wallis and Student-Newman-Keuls tests (α =0.05). RESULTS: Positive control sections exhibited complete dye penetration and negative control had no specimen showing marginal leakage. X-Temp LC and Coltosol showed similar results, with no statistical difference between them. Vitro Fill exhibited the highest dye penetration among the experimental groups. CONCLUSION: The results of this in vitro study suggest that all temporary restorative materials exhibit some degree of marginal leakage. X-Temp LC and Coltosol, however seal better than Vitro Fill glass ionomer cement.

3D-microleakage assessment of adhesive interfaces: exploratory findings by µCT.

OBJECTIVES: To explore the feasibility of a 3D-microleakage protocol for the evaluation of various configurations of adhesive-tooth interfaces. METHODS: Three different kinds of specimens were prepared: (1) a Class-I composite restoration placed without any bonding to maximize gap formation at the interface; (2) a glass-fiber post cemented with a self-adhesive composite cement into a prepared root canal; and (3) inlay MOD composite restorations placed with either a 1-step self-adhesive or a 2-step etch-and-rinse composite cement. After silver-nitrate (AgNO3) infiltration, the specimens were scanned using a Skyscan 1172 X-ray microtomograph (µCT; Skyscan Bruker) at 100kV, 100µA and 7.8-9.5µm resolution. Projection images were reconstructed, after which maximum-intensity projections (MIPs) and 3D-volumetric renderings were produced. For the inlays, an additional conventional stereomicroscopic (SM) microleakage evaluation was accomplished after specimen sectioning. RESULTS: MIPs and 3D-renderings from specimens (1) and (2) revealed strongly varying microleakage patterns along the marginal gap/interface. For the specimens of setup (3), the high radiopacity of the 2-step composite cement hindered evaluation of the MIPs. MIP-microleakage patterns along the enamel margin of the restoration cemented with the 1-step composite cement corresponded well to the stereomicroscopic images. SIGNIFICANCE: The reported µCT-protocol revealed good sensitivity to detect AgNO3 infiltration at the adhesive-tooth interface when considerable microleakage was present. When microleakage was less apparent and spread in a more diffuse pattern, evaluation with µCT was less sensitive compared to stereomicroscopic evaluation.

Estudo epidemiológico das fraturas coronárias em pacientes atendidos em um projeto de trauma dental em um período de 6 anos / Epidemiological study of coronal fractures in patients treated in a dental trauma project in a 6 years periods

O presente estudo teve como objetivo realizar um levantamento epidemiológico sobre os casos de fratura coronária em pacientes que foram atendidos no Projeto Trauma Dental da Escola de Odontologia da Unigranrio, no período de 2005 a 2011. O estudo foi baseado nos dados coletados dos prontuários e as informações obtidas estão relacionadas ao gênero, idade, etiologia da fratura, local do pronto atendimento, tempo decorrido até o pronto atendimento, dentes acometidos, situação clínica e a necessidade de tratamento endodôntico. Foi observada uma maior incidência em pacientes do gênero masculino, com a idade mais afetada entre 6 e 10 anos. Os resultados mostram a distribuição etiológica, clínica e demográfica das fraturas coronárias em um projeto de trauma dentário na cidade de Duque de Caxias.

The aim of the present study was to conduct an epidemiological survey on coronal fracture cases in patients treated at the Dental Trauma Project at Unigranrio School of Dentistry, from 2005 to 2011. This study was based on data collected from records and information related to gender, age, fracture cause, prompt service, elapsed time from the accident, affected teeth, clinical condition of the teeth and the need of endodontic treatment. It was observed a higher incidence in male patients, with the most affected age between 6 to 10 years. The results show the etiological, clinical and demographic distribution of coronal fractures in a project of dental trauma in Duque de Caxias city.

Does DIAGNOdent provide a reliable caries-removal endpoint?

OBJECTIVES: To compare mineral density of residual dentine after excavation with different caries-removal techniques and to evaluate the diagnostic potential of laser-induced fluorescence (LIF), measured by DIAGNOdent, as a tool to determine the caries-removal endpoint. METHODS: Carious teeth were excavated by tungsten-carbide round burs (Komet), ceramic burs (CeraBurs, Komet), sono-abrasion (Cariex TC tips, Kavo), and by chemo-mechanical excavation using two enzyme-based solutions (exp. SFC-V and SFC-VIII, 3M-ESPE) or a sodium hypochlorite-based solution (Carisolv, MediTeam). The caries-excavated teeth were scanned by micro-CT (1172, Skyscan), after which the mineral density at the bottom dentine was correlated to LIF measurements at the same region. A micro-CT threshold for dentine caries was defined by comparison with surface-hardness measurements. The intensity of dentine staining was evaluated by analysing the component 'L*' in CIE-L*a*b-converted images from the excavated teeth. RESULTS: No statistically significant difference in mineral density was found at the bottom of the cavities prepared with the different caries-excavation techniques, except for exp. SFC-V that left residual dentine with a significantly higher mineral density than when CeraBurs were used (Tukey-Kramer, p<0.05). Absence of residual caries was associated with darker staining of dentine. No significant correlation was found between the distance from the deepest cavity point to the pulp-chamber roof and LIF measurements. A strong negative correlation (R=-0.86, p<0.01) was however found between L* values and LIF measurements, indicating that staining in residual dentine leads to higher LIF measurements. CONCLUSIONS: LIF measured by DIAGNOdent is influenced by staining in residual dentine. Therefore, its use to determine the caries-removal endpoint is doubtful.

Biological restorations as an alternative treatment for primary posterior teeth.

A case of oral rehabilitation in a 4-year-old girl, in which the posterior teeth were restored using biological restorations, is described. The tooth fragments were selected from a bank of tooth tissues and bonded with dual-cure composite cement to prepared teeth. The results were satisfactory regarding retention, aesthetic and mastication, but disadvantages included long clinical appointments, laborious technique and possible fracture or degradation between the margins of the fragment and the tooth surface.

Levels of infection and colonization of some oral bacteria after use of naf, chlorhexidine and a combined chlorhexidine with naf mouthrinses

O objetivo deste estudo foi avaliar os níveis de infecção de bactérias cariogênicas e estreptococos orais e sua colonização após uso de bochechos com NaF, clorexidina e clorexidina e NaF associados. Associação de clorexidina e NaF foi o único agente que reduziu os níveis de Streptococcus mutans (grupo) por 30 dias.