Dental pulp tissue engineering in full-length human root canals.

The clinical translation of stem-cell-based dental pulp regeneration will require the use of injectable scaffolds. Here, we tested the hypothesis that stem cells from exfoliated deciduous teeth (SHED) can generate a functional dental pulp when injected into full-length root canals. SHED survived and began to express putative markers of odontoblastic differentiation after 7 days when mixed with Puramatrix™ (peptide hydrogel), or after 14 days when mixed with recombinant human Collagen (rhCollagen) type I, and injected into the root canals of human premolars in vitro. Roots of human premolars injected with scaffolds (Puramatrix™ or rhCollagen) containing SHED were implanted subcutaneously into immunodeficient mice (CB-17 SCID). We observed pulp-like tissues with odontoblasts capable of generating new tubular dentin throughout the root canals. Notably, the pulp tissue engineered with SHED injected with either Puramatrix™ or rhCollagen type I presented similar cellularity and vascularization when compared with control human dental pulps. Analysis of these data, collectively, demonstrates that SHED injected into full-length human root canals differentiate into functional odontoblasts, and suggests that such a strategy might facilitate the completion of root formation in necrotic immature permanent teeth.

Adhesive temperature: effects on adhesive properties and resin-dentin bond strength.

OBJECTIVES: To evaluate the effect of adhesive temperature on the resin-dentin bond strength (µTBS), nanoleakage (NL), adhesive layer thickness (AL), and degree of conversion (DC) of ethanol/water- (SB) and acetone-based (PB) etch-and-rinse adhesive systems. METHODS: The bottles of the two adhesives were kept at each temperature (5°C, 20°C, 37°C, and 50°C) for 2 hours before application to demineralized dentin surfaces of 40 molars. Specimens were prepared for µTBS testing. Bonded sticks (0.8 mm(2)) were tested under tension (0.5 mm/min). Three bonded sticks from each tooth were immersed in silver nitrate and analyzed by scanning electron microscopy. The DC of the adhesives was evaluated by Fourier transformed infrared spectroscopy. RESULTS: Lower µTBS was observed for PB at 50°C. For SB, the µTBS values were similar for all temperatures. DC was higher at 50°C for PB. Higher NL and thicker AL were observed for both adhesives in the 5°C and 20°C groups compared to the 37°C and 50°C groups. The higher temperatures (37°C or 50°C) reduced the number of pores within the adhesive layer of both adhesive systems. CONCLUSIONS: It could be useful to use an ethanol/water-based adhesive at 37°C or 50°C and an acetone-based adhesive at 37°C to improve adhesive performance.

Evaluation of two mineral trioxide aggregate compounds as pulp-capping agents in human teeth.

AIM: The present randomized, controlled prospective study evaluated the histomorphological response of human dental pulps capped with two grey mineral trioxide aggregate (MTA) compounds. METHODOLOGY: Pulp exposures were performed on the occlusal floor of 40 human permanent pre-molars. The pulp was capped either with ProRoot (Dentsply) or MTA-Angelus (Angelus) and restored with zinc oxide eugenol cement. After 30 and 60 days, teeth were extracted and processed for histological examination and the effects on the pulp were scored. The data were subjected to Kruskal-Wallis and Conover tests (alpha = 0.05). RESULTS: In five out of the 40 teeth bacteria were present in pulp tissue. No significant difference was observed between the two materials (P > 0.05) in terms of overall histological features (hard tissue bridge, inflammatory response, giant cells and particles of capping materials). Overall, 94% and 88% of the specimens capped with MTA-Angelus and ProRoot, respectively, showed either total or partial hard tissue bridge formation (P > 0.05). CONCLUSIONS: Both commercial materials ProRoot (Dentsply) and MTA-Angelus (Angelus) produced similar responses in the pulp when used for pulp capping in intact, caries-free teeth.

Response of human dental pulp capped with MTA and calcium hydroxide powder.

OBJECTIVES: To compare the response of human dental pulp capped with a mineral trioxide aggregate (MTA) and Ca(OH)2 powder. METHODS AND MATERIAL: Pulp exposures were performed on the occlusal floor of 40 permanent premolars. The pulp was then capped with either Ca(OH)2 powder (CH) or MTA and restored with resin composite. After 30 days (groups CH30 and MTA30) and 60 days (groups CH60 and MTA60), the teeth were extracted and processed for HE and categorized in a histological score system. The data were subjected to Kruskal-Wallis and Conover tests (alpha = 0.05). RESULTS: In regard to dentin bridge formation, CH30 showed a tendency towards superior performance compared to MTA30 (p > 0.05), although the products showed comparable results at day 60. In the item "Inflammation" and "General State of the Pulp" (p > 0.05), CH showed a tendency towards presenting a higher inflammatory response. In the item "Other Pulpal Findings," MTA and Ca(OH)2 showed equal and excellent performance after 30 and 60 days (p > 0.05). CONCLUSION: After 30 days, Ca(OH)2 powder covered with calcium hydroxide cement showed faster hard tissue bridge formation compared to MTA. After 60 days, Ca(OH)2 powder or MTA materials showed a similar and excellent histological response with the formation of a hard tissue bridge in almost all cases with low inflammatory infiltrate.

A 2-year evaluation of moisture on microtensile bond strength and nanoleakage.

OBJECTIVES: This study evaluated the effect of moisture on the resin-dentin mu-bond strength (BS) and silver nitrate uptake (SNU) of three adhesive systems (Single Bond, One-Step and Syntac Single Component) soon after bonding (IM) and after 2 years of water storage (2Y). METHODS: Dentin surfaces were bonded on a dry (D), moist (W) or over-wet surfaces (OW). After restorations were constructed, specimens were stored in water (37 degrees C/24h). Resin-dentin sticks were prepared (0.8mm(2)) and they were divided for immediate (IM) and 2-year storage (2Y) testing. Half of the specimens from each period of time were tested in tension at 0.5mm/min and the other half was immersed in silver nitrate and examined by SEM-EDX. The data was analyzed by three-way repeated measures ANOVA and Tukey's tests (alpha=0.05). RESULTS: The overall BS (MPa) in the IM group under W condition was higher than in D and OW groups. After 2Y, the BS in W was lower than in the IM group, however higher than in the D and OW for OS and SB. The overall silver nitrate deposition (%) in the IM group under D, W and OW were similar. In the 2Y groups, the nanoleakage was higher than IM groups, however the increase was less pronounced in the W condition. SIGNIFICANCE: Higher BS and a significantly lower nitrate uptake were observed for IM groups, for OS and SB. Under W conditions, the BS reduction over time was less pronounced and less nitrate uptake occurred.

Clinical effectiveness of laser fluorescence, visual inspection and radiography in the detection of occlusal caries.

The aim of this in vivo study was to compare a laser fluorescence (LF) device with Ekstrand's visual scoring system and radiographic assessment for detection of occlusal caries. Thirty-eight adults aged 19-35 years participated in the study; a total of 57 third molars with macroscopically intact occlusal surfaces were selected. Two examiners assessed 110 sites by visual inspection (VI), bitewing radiography (BW) and LF. Teeth were then extracted and caries extent assessed by histology. The detection methods were compared by means of sensitivity, specificity, inter-examiner reproducibility (kappa statistics) and area under the ROC curve. VI and LF had similar (p > 0.05) and superior sensitivities than BW (p < 0.05). VI and BW showed similar specificities, which was superior to LF. The inter-examiner reproducibility was good for VI and BW and moderate for LF. The area under ROC curves showed that VI was better than LF. It was concluded that Ekstrand's visual scoring system is the most valid method for caries diagnosis. LF should be considered an adjunct to caries diagnosis.