Dentine-pulp tissue engineering in miniature swine teeth by set calcium silicate containing bioactive molecules.

OBJECTIVE: The present study aims to investigate whether reparative dentinogenesis could be guided at central pulpal sites or at a distance from the amputated pulp of miniature pig teeth, by using set calcium silicate-based carriers containing human recombinant bioactive molecules. DESIGN: Pulp exposures were performed in 72 permanent teeth of 4 healthy miniature swine. The teeth were capped with pre-manufactured implants of set calcium silicate-based material containing BMP-7, TGFß1 or WnT-1, for 3 weeks. Conical-shaped intrapulpal implants were exposed in the central pulp core, while disc-shaped extrapulpal implants were placed at a distance from the amputated pulp. Implants without bioactive molecules were used as controls. Thickness and forms of new matrix mineralized deposition were assessed histologically at post-operative periods of 3 weeks by light microscopy. RESULTS: Intrapulpal applications: Calcified structures composed of osteodentine were found in contact with the BMP-7 implants. An inhomogeneous calcified tissue matrix was found around the WnT-1 carriers. A two-zone calcified structure composed of osteodentine and a thicker tubular matrix zone was seen at the TGFß1 carrier-pulp interface. Extrapulpal applications: The space between WnT-1 implants and pulp periphery had been invaded by soft tissue with traces of calcified foci. Thick calcified structures composed of osteodentine were found surrounding pulp exposure sites in response to application of BMP-7. Spindle-shaped cells associated with atubular calcified matrix or elongated polarized cells associated with tubular dentine-like matrix were found along the cut dentinal walls of the TGFß1 group. CONCLUSION: The present experiments indicated that set calcium silicate could be used as carrier for biologically active molecules. TGFß1 was shown to be an effective bioactive molecule in guiding tertiary dentine formation.

Dentinogenic Activity of Biodentine in Deep Cavities of Miniature Swine Teeth.

INTRODUCTION: The aim of the present study was to evaluate comparatively the bioactivity potential of a calcium silicate-based material (Biodentine; Septodont, Saint-Maur-des-fosses Cedex, France) after the restoration of deep dentinal cavities of miniature swine teeth with or without the application of a calcium hydroxide-containing pulp protective base (Dycal; Caulk Lab, Milford, DE). METHODS: Thirty-three permanent teeth (premolars, canines, and incisors) of 3 miniature swine were used. Class V cavities were prepared on the buccal surface of teeth. The cavities were restored with Biodentine in the presence (control group) or absence (experimental group) of a Dycal protective base. The pulpal tissue responses were histologically and histomorphometrically assessed at postoperative periods of 3 and 8 weeks. Three specimens were further evaluated with scanning electron microscopy. The maximum thickness of the postoperatively formed mineralized matrix beneath the cavity floor was measured. Data were statistically analyzed by the Kruskal-Wallis and the Mann-Whitney U tests. RESULTS: A bacterial staining reaction along the cavity walls or intense inflammatory infiltration in the pulp was not detected in any of the specimens. A continuous zone of the postoperatively formed mineralized matrix mostly of atubular structure with scattered defects and cellular inclusions and occasionally followed by a thin zone with tubular morphology was detected in all specimens of the control group and 13 of 18 experimental group teeth. In the remaining teeth of the experimental group, a separate zone composed of the osteotypic mineralized matrix and soft tissues was noted between the circumpulpal and the newly formed matrix. Scanning electron microscopy confirmed the fibrous structural morphology of the tertiary dentin. A significantly higher rate of the postoperatively formed mineralized matrix had been formed in the teeth of the experimental group in both periods of 3 and 8 weeks (P < .01). CONCLUSIONS: The present investigation indicates that under the present experimental conditions tertiary dentin with occasional intermediate formation of osteodentin is observed after the application of Biodentine in the presence or absence of a Dycal protective base. The thickness of the tertiary dentine zone was significantly higher in the absence of Dycal.

Dentinogenic responses after direct pulp capping of miniature swine teeth with Biodentine.

INTRODUCTION: The aim of this study was to evaluate pulpal responses after experimental direct pulp capping of mechanically exposed teeth with a new calcium silicate-based dentin replacement material. METHODS: Thirty-four anterior and posterior teeth of 3 miniature swine were used. Class V or I cavities were prepared on the buccal or occlusal surfaces, respectively. Pulpal exposures were further performed using a round carbide bur 0.8 mm in diameter. Exposures were treated with white MTA Angelus (Angelus, Londrina, PR, Brazil) or Biodentine (Septodont, Saint Maur des Fosses, France), and the cavities were further restored with Biodentine. The pulpal tissue responses were histologically assessed at postoperative periods of 3 and 8 weeks. Data were statistically analyzed using the Kruskal Wallis and the Mann-Whitney U tests. RESULTS: Inflammatory infiltration or pulp tissue necrosis was not found in any of the specimens. All teeth showed mineralized matrix formation in the form of a complete hard tissue bridge composed of osteodentin or osteodentin followed by a discontinuous or continuous reparative dentin zone. A significantly higher thickness of the hard tissue bridge was found in the group of teeth treated with Biodentine at both 3 and 8 weeks. A number of teeth, which were under root development at the onset of the experimental procedures, exhibited ectopic pulp calcification. CONCLUSIONS: The application of both calcium silicate-based materials in direct contact with the mechanically exposed pulp of healthy miniature swine teeth led to pulp repair with complete hard tissue bridge formation. The thickness of hard tissue bridges was significantly higher after pulp capping with Biodentine.

Effect of fluoride solutions on the structure and hardness of plastic brackets.

AIM: To investigate the surface morphology, structure, molecular and elemental composition, and hardness of plastic brackets exposed to fluoride solutions. METHODS: Two types of plastic brackets (Silkon Plus and SpiritMB) were exposed to three fluoride solutions 10 times for 1 minute each and then subjected to attenuated total relectance-Fournier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), x-ray energy dispersive microanalysis (EDS), and Vickers hardness (HV) testing. Hardness data were analyzed via two-way ANOVA and Tukey tests at the .05 level of significance with brackets and fluoride solution as predictors. RESULTS: ATR-FTIR spectroscopy showed that both bracket types consisted of polycarbonate. After treatment with acidulated phosphate fluoride, an increased contribution of -OH peaks at 3,200 cm-1(stretching [str]) and 1,640 cm-1 (a type of vibration [b]) was observed in both brackets. SEM revealed that the acidulated phosphate fluoride solution had a strong effect on the morphology and surface structure of the two brackets; a general deterioration with projections of the reinforcing fibers was observed. EDS showed evidence of aluminum, calcium, silicon, magnesium, and titanium, which could be attributed to the reinforcing glass fiber constituents. Hardness ranged in the order of 20 HV with no difference among the two bracket types and the three fluoride exposures. CONCLUSION: Repeated exposure of plastic brackets to fluoride solutions has a pronounced effect on their structure and morphology, but not their hardness.

Effect of simulated pulpal microcirculation on intrachamber temperature changes following application of various curing units on tooth surface.

OBJECTIVE: The purpose of this study was to evaluate ex vivo the rise in intrachamber temperature induced by the application of various curing units on tooth surface, under conditions of continuous water flow inside the pulp chamber simulating pulp microcirculation. METHODS: Fifteen extracted intact human teeth were selected. Intrachamber temperature increases were induced by applying the following curing units to the buccal aspect of the tested teeth: a conventional halogen lamp, two high-intensity halogen lamps, a plasma arc curing light, a mercury/metal-halide lamp, and a diode laser. Temperature changes on the tooth surfaces were recorded using thermocouples connected to a data logger. The Greenhouse-Geisser and Bonferroni tests in the SPSS software package were used for analysis of the data. The level of significance was set at 0.05. RESULTS: Under conditions of water flow the average intrachamber temperature rise was less than 6 degrees C, for all curing units. Without water flow, the increase in pulp temperature exceeded 6 degrees C for all units except the conventional halogen lamp. The diode laser produced a significantly greater temperature increase than any other curing unit. Application of the diode laser and the two high-intensity halogen lamps to lateral incisor specimens produced significantly greater temperature increases than other teeth. CONCLUSIONS: When the simulated pulp microcirculation was absent, the temperature increases produced by all curing units except the conventional halogen lamp were large enough to be potentially harmful to the pulp. On the contrary, with the cooling effect of water flow inside the pulp chamber, all units proved to be safe for use.