Digital Photocolorimetric Analysis of In Vitro Tooth Color Changes.

OBJECTIVE: Tooth color matching is challenging, and digital photocolorimetry using eLABor_aid (eLAB) provides objective evaluation through polarized photographs. However, its comparability with spectrophotometry remains unclear. METHODS AND MATERIALS: Bovine incisor root canals (n=30) were prepared to simulate an incomplete root apex. The teeth were randomly assigned to three groups based on intracanal medication: control (without medication); calcium hydroxide/propylene glycol; and triple-antibiotic paste (n=10 each). Tooth color was assessed using both eLAB and spectrophotometry. Measurements were taken at the crown medio-cervical region on five-time intervals (baseline, 1, 3, 7, and 14 days). Statistical analysis included two-way repeated-measures ANOVA, Sidak post hoc and Pearson's correlation test (α=0.05). RESULTS: No significant differences were observed between the two methods for either medication or follow-ups (p>0.05). Triple-antibiotic paste exhibited higher color variation (p<0.05). After 7 days, all groups presented significant color changes (p<0.05). Moderate to high correlations (R2 from 0.51 to 0.84, p<0.0001) were found between both methods for all groups at all intervals. CONCLUSION: The eLAB is a reliable method for detecting tooth color changes, and its results are comparable to spectrophotometry analysis.

The effect of feeding on the respiratory activity of the sloth.

The aim of the present study was to confirm whether feeding influences the resting breathing rate and to observe possible alterations in blood gas and pH levels produced by feeding in unanesthetized sloths (Bradypus variegatus). Five adult male sloths (4.1 +/- 0.6 kg) were placed daily in an experimental chair for a period of at least 4 h for sitting adaptation. Five measurements were made for each sloth. However, the sloths one, two and five were studied once and the sloths three and four were studied twice. Breathing rate was determined with an impedance meter and the output signal was digitized. Arterial blood samples were collected for blood gas analysis with a BGE electrolytes analyzer and adjusted for the animal's body temperature and hemoglobin content. The data are reported as mean +/- SD and were collected during the resting period (8:00-10:00 h) and during the feeding period (16:00-18:00 h). The mean breathing rate increased during mastication of ymbahuba leaves (rest: 5.0 +/- 1, feeding: 10 +/- 1 bpm). No significant alterations were observed in arterial pH (rest: 7.42 +/- 0.05, feeding: 7.45 +/- 0.03), PCO2 (rest: 35.2 +/- 5.3, feeding: 33.3 +/- 4.4 mmHg) or PO2 (rest: 77.5 +/- 8.2, feeding: 78.4 +/- 5.2 mmHg) levels. These results indicate that in unanesthetized sloths 1) feeding evokes an increase in breathing rate without a significant change in arterial pH, PCO2 or PO2 levels, and 2) the increase in breathing rate produced by feeding probably is due to the act of mastication.

The effect of feeding on the respiratory activity of the sloth

The aim of the present study was to confirm whether feeding influences the resting breathing rate and to observe possible alterations in blood gas and pH levels produced by feeding in unanesthetized sloths (Bradypus variegatus). Five adult male sloths (4.1 ± 0.6 kg) were placed daily in an experimental chair for a period of at least 4 h for sitting adaptation. Five measurements were made for each sloth. However, the sloths one, two and five were studied once and the sloths three and four were studied twice. Breathing rate was determined with an impedance meter and the output signal was digitized. Arterial blood samples were collected for blood gas analysis with a BGE electrolytes analyzer and adjusted for the animal's body temperature and hemoglobin content. The data are reported as mean ± SD and were collected during the resting period (8:00-10:00 h) and during the feeding period (16:00-18:00 h). The mean breathing rate increased during mastication of ymbahuba leaves (rest: 5.0 ± 1, feeding: 10 ± 1 bpm). No significant alterations were observed in arterial pH (rest: 7.42 ± 0.05, feeding: 7.45 ± 0.03), PCO2 (rest: 35.2 ± 5.3, feeding: 33.3 ± 4.4 mmHg) or PO2 (rest: 77.5 ± 8.2, feeding: 78.4 ± 5.2 mmHg) levels. These results indicate that in unanesthetized sloths 1) feeding evokes an increase in breathing rate without a significant change in arterial pH, PCO2 or PO2 levels, and 2) the increase in breathing rate produced by feeding probably is due to the act of mastication