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.

Clinical evaluation of an adhesive used as a fissure sealant.

PURPOSE: To compare the retention of a multi-use bonding agent (OptiBond) to a conventional sealant (Delton) used as pit and fissure sealants. MATERIALS AND METHODS: An informed consent was obtained from 38 subjects aged 11-17 yrs. Delton, a self-cured sealant, was applied to 86 teeth, and OptiBond, a dual-cure glass filled adhesive, was applied to 85 teeth, under cotton roll isolation and saliva ejector. Each subject received both sealing materials, randomly assigned to the sides of the mouth. The sealed teeth were followed up to 30 months. Clinical evaluation was performed by two examiners and the retention was classified as failure or success. RESULTS: Statistical analysis based on a stratified Cox proportional hazards regression model indicated that OptiBond had better clinical performance than Delton (P < 0.001).

Bonding systems used for sealing: evaluation of microleakage.

To evaluate multi-use bonding systems as the sole material for sealing pits and fissures, this study compared the performance of three adhesives (OptiBond, All-Bond 2 and Scotchbond MP Plus) with respect to microleakage. Each material was applied to 12 teeth with dry-etched surfaces, and to 12 teeth with contaminated-etched surfaces (1 microliter of human plasma). Each group of 12 sealed teeth was divided into three subgroups, and each of these was subjected either to thermal cycling (4,000 cycles at 5-55 degrees C), to thermal and load cycling (4,000 plus 300,000 cycles) or to no cycling. The teeth were placed in a 50% AgNO3 solution, rinsed, immersed in a developing solution and exposed to a fluorescent light. Subsequently, each of the 72 crowns was sectioned at three different positions, generating 432 cross-sections. The severity of dye penetration on each cross-section was evaluated by two methods. An ANOVA was used to assess the main effects of the three factors (product, surface condition and cycling), as well as for their interactions on the severity of microleakage. The results obtained under both evaluation methods demonstrated that OptiBond had the best performance under either dry or contaminated surfaces, while All-Bond 2 and Scotchbond MP Plus performed similarly, with greater microleakage intensity on contaminated etched enamel compared to OptiBond.

Microleakage of a universal adhesive used as a fissure sealant.

PURPOSE: To evaluate the microleakage of a universal hydrophilic adhesive (OptiBond dual-cure) by itself as a pit and fissure sealant compared to that of an ionomeric product (VariGlass) and two hydrophobic sealants (Delton and Fluroshield). MATERIALS AND METHODS: Sixty-four extracted human third molars were sealed with one of these four materials under either a conventional procedure (free of humidity) or after contamination of the etched surfaces with 3 microliters of human plasma. The sealed teeth were subjected to 1,500 thermocycles (1 min/5-55 degrees C) and to 450,000 mechanical cycles under an 8.5 kgf average load at 37 degrees C. The tooth crowns were partially coated with nail varnish, immersed in a 50% aqueous solution of AgNO3 for 2 h in darkness, washed and then developed for 8 h under fluorescent light. The teeth were sectioned and dye penetration was scored according to a 4-point scale by four trained professionals. RESULTS: An ANOVA suggested that under no humidity conditions, the average score for VariGlass (1.92 +/- 0.36) was significantly higher (P = 0.0006) than that corresponding to the three remaining materials (1.28 +/- 0.20) which were considered equivalent. Under humid (plasma contaminated) conditions, there was complete loss of Delton and Fluroshield in all cases, whereas the average score for VariGlass (1.98 +/- 0.36) was slightly higher (P = 0.0444) than that for OptiBond (1.62 +/- 0.36). These results suggest that OptiBond may be used by itself as a pit and fissure sealant instead of the combination of adhesive plus sealant.

The influence of a mineralizing mouthrinse on the mineral contents and on the pH of dental plaque.

The main objective of this study was to evaluate the effects of a single use of a mineralizing mouthrinse on dental plaque pH and on its mineral contents: an additional objective was to examine the effects of an oral prophylaxis and scaling on the same response variables. A total of 22 volunteer dental students (14 female and 8 male) participated in the study. The mineralizing mouthrinse contained calcium, phosphate, strontium and fluoride ions. Following a 48-hour period without oral hygiene and 2 hours after breakfast, dental plaque was collected twice from each participant for the evaluation of the effects of the oral prophylaxis and scaling, and twice more for the evaluation of the effects of the mineralizing mouthrinse. The pH was measured in vitro with a microelectrode and the mineral contents were determined by atomic emission spectrometry. The results demonstrate that the average post-prophylaxis pH was higher than the average pre-prophylaxis pH, and that a variation of the average contents of some minerals in the dental plaque was also observed after prophylaxis compared to the contents prior to prophylaxis. Although there was a significant reduction in the Fe content after the rinse with the mineralizing solution, no significant variation on the average pH was detected.

Effectiveness of three mouthrinses to inhibit acid formation by dental plaque under home-use conditions.

A study was conducted to assess the effectiveness of three mouthrinses (Plax, Cepacol and Fluordent) to inhibit acid formation from plaque collected from 21 volunteer dental students. Plaque was collected on each side of the mouth, two hours after breakfast, once-a-week, after a period of 48 hours without any oral hygiene other than the use of the mouthrinses. Initial pH and the change in pH of plaque incubated with sucrose were recorded up to 120 min. Excepting Cepacol for the first week only, no inhibitory effect on acid formation was observed.