Blood Flow In Dental Pulp Research Articles

Assesment of radiotherapy effects on the blood flow in gingiva and dental pulp - a laser Doppler flowmetry study

This study aims to determine and compare the dental pulp and gingival blood flow in patients referred for oropharyngeal radiotherapy (RT) at three different time points: before the start, immediately after, and six months following the completion of RT. The aim is also to evaluate the dependence of the pulp and gingival blood flow on the radiation dose. A prospective study included 10 patients referred for intensity-modulated RT (IMRT) in the oropharyngeal region, with at least one intact tooth surrounded by a healthy gingiva. The dose received by each selected tooth and adjacent gingiva was determined according to the map of treatment planning and computer systems. The blood flow measurements were performed using the laser Doppler flowmetry (LDF) method. Comparing vascular flows at three different time points, the median blood flow in the dental pulp showed no statistically significant difference (p=0.325), contrary to gingiva (p=0.011). Immediately after RT completion, the gingival flow significantly increased compared to its starting point (p=0.012). The pulp flow correlated negatively with the radiation dose, whereas a strong correlation was noted 6 months following the RT completion. RT caused a significant acute gingival blood flow increase, followed by a long-term (over six months) tendency to return to the starting levels. The dental pulp blood flow is differently affected by higher radiation doses (over 50Gy) in comparison to lower doses (below 50Gy). During RT planning, considering the possibility of protecting the teeth localized near the Gross Tumor Volume as a sensitive organ is recommended.

Effects of Local Anesthetics With Vasoconstrictors on Dental Pulp Blood Flow and Oxygen Tension.

The aim of this study was to investigate the changes in pulpal blood flow (PBF) and pulpal oxygen tension (PpulpO2) after injecting local anesthetics with vasoconstrictors. Under general anesthesia, male Japanese White rabbits were injected with 0.6 mL of 2% lidocaine with 1:80,000 epinephrine (LE) or 3% propitocaine (prilocaine) with 0.03 IU felypressin (PF) at the apical area of the lower incisor. Relative to baseline, PBF and PpulpO2 significantly decreased 5 minutes after LE or PF injection as compared with saline. The decrease in PBF was significantly lower in the LE group than in the PF group. Although the LE group had a larger decrease in PpulpO2 relative to baseline than the PF group did, that difference was not significant. PBF and PpulpO2 recovered to baseline faster in the PF group than in the LE group. The injection of local anesthetic solutions containing vasoconstrictors (LE or PF) transiently caused significant decreases in PBF that resulted in significant decreases in PpulpO2. The recovery of PpulpO2 was faster than PBF regardless of the vasoconstrictor used.

Linear and nonlinear analysis of dental pulp blood flow oscillations in ageing.

To investigate the effect of ageing on control mechanisms of pulpal microcirculation using wavelet analysis and to calculate linear and nonlinear parameters of blood flow oscillations, in a healthy general population. Pulpal blood flow (PBF) oscillations were recorded on right maxillary central incisors using laser Doppler Flowmeter (PeriFlux PF 5001, Perimed, Jarfalla, Sweden) on a group of 10 young participants (20-25years) and a group of 10 older adults (60-70years). In total, 20 recordings were obtained for at least 20min (one recording on one tooth per subject). Using wavelet spectral analysis, the amplitude and power were calculated as a linear and Hurst exponent as a nonlinear parameter of PBF oscillations. Differences between the two groups were assessed with the independent Student t-test. Mean PBF levels were significantly lower (P=0.024) in older adults than in young participants. Relative amplitudes and powers corresponding to the myogenic (P=0.046, P<0.001, respectively) and neurogenic activity (P=0.04, P=0.01, respectively) were significantly higher, whereas values corresponding to the endothelial function (P=0.04, P=0.01, respectively) were significantly lower in older adults than in young participants. Hurst exponents of the total spectrum, myogenic and endothelial component (P<0.001, P=0.02, P<0.001, respectively) of PBF oscillations were significantly lower in older adults in comparison to young participants. At the level of pulpal microcirculation, ageing was associated with altered blood flow levels, the contribution of different control mechanisms to blood flow oscillations as well as the interaction of vascular smooth muscle and endothelium. Described changes of pulpal haemodynamics contribute to a better understanding of physiological behaviour and decreased adaptability of aged dental pulp to pathological stimuli.

Effect of Aging and Carotid Atherosclerosis on Multifractality of Dental Pulp Blood Flow Oscillations

IntroductionAge-related changes of dental pulp tissue and atherosclerosis of carotid arteries as its feeding arteries could influence the functionality of pulpal circulation. The objective of our study was to evaluate the effect of aging (physiological process) and carotid bifurcation atherosclerosis (pathologic process) on the pulpal microcirculatory system using multifractal analysis of the laser Doppler flowmetry signal. MethodsThree groups of 10 subjects were enrolled in the study: the young group (healthy subjects, 20–25 years), the middle-aged group (healthy subjects, 50–60 years), and the clinical group (subjects with carotid bifurcation atherosclerosis, 50–60 years). Pulpal blood flow (PBF) signals recorded by laser Doppler flowmetry were assessed by multifractal analysis that estimates Hölder exponents of the signal. PBF levels, the average mean values, and the range of Hölder exponents were obtained. ResultsPBF levels were significantly higher in the young group compared with the middle-aged and clinical groups, and the difference between the middle-aged and clinical groups was not statistically significant. The range of the Hölder exponents was narrower in the middle-aged and clinical groups than in the young group and narrower in the clinical group than in the middle-aged group. The average mean value of Hölder exponents was significantly higher in the young group than in the middle-aged and clinical groups, whereas there was no significant difference between the middle-aged and clinical groups. ConclusionsOur study investigating the multifractality of the PBF signal showed that the aging process and carotid atherosclerosis could affect the complex structure of PBF oscillations and contribute to a better understanding of pulpal hemodynamics.

Prolonged release of iloprost enhances pulpal blood flow and dentin bridge formation in a rat model of mechanical tooth pulp exposure.

The aim of this study was to investigate the effect of prolonged release of iloprost, a prostacyclin analog, on angiogenesis and dental pulp healing in a rat model of mechanical pulp exposure. The profile of iloprost release from poly (lactic-co-glycolic) acid (PLGA) microspheres was evaluated, and expression of vascular endothelial growth factor (VEGF) mRNA was determined. The molars of rats were subjected to mechanical pulp exposure and 5 different forms of treatment: Ca(OH)2, PLGA (blank), iloprost, and iloprost/PLGA. Blood flow was determined at 0, 3, and 7 days using laser Doppler flowmetry. After 30 days, the tooth specimens were collected, and subjected to micro-CT and immunohistological analysis. The results showed that iloprost release from the microspheres was prolonged for 4 days, and that the treatment increased tooth blood flow for up to 7 days. At 30 days, an increase of mineralized tissue formation and dentin bridge formation was observed in the iloprost and iloprost/PLGA microsphere groups. VEGF expression was significantly increased in the iloprost/PLGA microsphere group relative to the other groups. In conclusion, this PLGA microsphere iloprost delivery system significantly increased dental pulp blood flow in a prolonged manner and increased tertiary dentin formation in this rat pulp injury model. Prolonged prostacyclin release could be a potentially useful approach for regeneration of dental pulp.

Changes in dental pulp blood flow of different maxillary tooth types after Le Fort I osteotomy.

This study examined the effects of Le Fort I (LF-I) osteotomy on pulpal blood flow (PBF) in maxillary teeth during a 12-month postsurgical period. A laser Doppler flowmeter was used to measure PBF in maxillary incisors, canines, and first premolars of 14 patients undergoing LF-I osteotomy (study group), 7 patients undergoing mandibular osteotomy (surgical control group), and 7 nonsurgical controls. The PBF was measured at baseline (preoperatively) and at 1 week and 1, 3, 6, and 12 months postoperatively and at similar intervals in nonsurgical control subjects. Data were evaluated using Kruskal-Wallis and post hoc Mann-Whitney tests. Changes in PBF over time for each tooth type were evaluated using the Wilcoxon signed-rank test. The level of significance was set at P < 0.05. Study findings showed that baseline PBF values did not differ significantly between groups. Maxillary PBF in the control group did not vary over time; however, an initial decrease in PBF was observed in all tooth types immediately after surgery in the study group. A gradual increase to near-preoperative levels was then observed during a 12-month healing period. Although dramatic reductions in maxillary perfusion of the first premolar and canine pulps were observed at 1 week and 1 month after LF-I osteotomy when compared with baseline (P < 0.001), PBF significantly recovered over time. Moreover, hyperemia was observed in lateral incisors 3 months postoperatively, demonstrating a tooth type-specific effect of LF-I osteotomy on PBF.

Changes in maxillary incisor dental pulp blood flow during intrusion by mini-implants

Aim. The aim of this clinical study was to identify changes in pulpal blood flow (PBF) in human central incisors resulting from short- and long-term intrusive orthodontic forces from mini-implants. Materials and methods. A total of 40 sound upper central and lateral incisors in 20 patients scheduled for intrusion for orthodontic reasons were divided into two groups. From each group, 20 teeth were subjected to intrusive force from mini-implants (Group 1 = Light Force: 40 g; Group 2 = Heavy Force: 120 g), whereas the remaining 20 contralateral teeth were not subjected to forces from mini-implants and served as controls. Laser-Doppler flowmetry (LDF) measurements were recorded at baseline and at 3 days and 3 weeks following intrusion. Results. PBF decreased significantly at 3 days (Light Force Group: 7.72 ± 0.50; Heavy Force Group: 7.72 ± 0.52) and then increased towards baseline at 3 weeks (Light Force Group: 10.37 ± 0.58; Heavy Force Group: 10.31 ± 0.45) following intrusion. Conclusions. In other words, despite slight regressive changes in pulpal tissue in the short-term, PBF improved after 3 weeks following intrusion by mini-implants, indicating that the changes observed in PBF is reversible, even following radical incisor intrusion.

オトガイ部におけるNd:YAGレーザー照射によるヒト歯髄血流量および歯髄温度感覚閾値への影響

オトガイ部におけるNd:YAGレーザー照射によるヒト歯髄血流量および歯髄温度感覚閾値への影響

치수혈류 측정을 위한 광 프로브 개발

To diagnose dental pulp vitality, electric pulp tester has been widely used, which is a method to test condition of nerve. However, especially in the case of patients with trauma, nerve desensitization could temporarily occur even though nerve might be recovered by blood flow within the pulp later, which implies that blood flow in dental pulp is also an important factor for diagnosing vitality. This paper described the development of a probe that relatively measured blood flow in dental pulp using photoplethysmography (PPG). The probe emits four different wavelength light sources including three visible and an infrared light. We tested which light source detect sensitively the blood flow in dental pulp. As a result, green light had the largest peak to peak voltage and the power spectrum among different wavelengths.

Dental Pulp Blood Flow and Its Oscillations in Women with Different Estrogen Status

IntroductionThe skin microcirculation is significantly affected by serum estrogen levels. The objective of this study was to investigate the effects of estrogen serum level changes associated with the menstrual cycle and postmenopause on dental pulp blood flow (PBF) as well as its dynamics. MethodsYoung women at the menstrual phase (low serum estrogen levels) and in the mid-cycle phase of the menstrual cycle (high serum estrogen levels) and postmenopausal women were enrolled in the study. PBF and its oscillations were measured by laser Doppler flowmetry and analyzed by using wavelet transform. Serum levels of estradiol-17β were measured by immunoassay. ResultsPBFs of young women in the menstrual phase and postmenopausal women were mutually similar and significantly lower than those of young women in the mid-cycle period. With respect to the mid-cycle phase, relative amplitude and power were significantly increased in the interval 0.0095–0.02 Hz and decreased in the intervals 0.02–0.06 and 0.06–0.2 Hz in the menstrual phase. A significant decrease in 0.0095–0.02 Hz and increase in 0.02–0.06, 0.06–0.2, 0.2–0.6, and 0.6–1.6 Hz intervals were observed in postmenopause. ConclusionsThe study has shown that the menstrual phase of the menstrual cycle and postmenopause have similar PBF decrease, but PBF oscillations are differently affected in the mid-cycle phase.

Measurement of pulpal blood flow in dogs with nonradioactive colored microspheres.

The viability of dental pulp depends largely on regional blood flow, as in other organs. Measurement of absolute pulpal blood flow (PBF) and comparisons with blood flow in other organs allow the prediction of microvascular regulation in dental pulp. In previous studies, PBF was measured in dogs mainly with radioactive microspheres. However, this established technique is inaccessible to many investigators due to concerns over radiation safety and radioactive waste. To overcome these limitations, a new method has been introduced that involves the use of nonradioactive colored microspheres for measuring regional blood flow in the myocardium and in other organs in animals. However, no previous studies have investigated the use of this method to measure PBF in dogs. We attempted to determine whether blood flow in dental pulp, which comprises a small amount of the total tissue in dogs, could be measured using this technique by comparing the measured values with those for regional myocardial blood flow. Mean blood flow values were between 0.148 and 0.182 ml/min/g for dental pulp at four different sites and about 1.0 ml/min/g in regional myocardium. These values are comparable to those previously reported using radioactive microspheres. As nonradioactive colored microspheres safety permitted measurement of absolute PBF in dogs, this technique appears to be useful for research into microvascular blood flow in dental pulp.

Evaluation of the process of recovery of dental pulp after Le Fort I osteotomy

Le Fort I osteotomy has been established by many studies and is generally used, but hypoesthesia of the dental pulp, the most common complication, occurs in almost all patients. As such, we examined dental pulp sensibility, pulpal blood flow, and histological changes, to elucidate the process of functional recovery of dental pulp after Le Fort I osteotomy. Monkeys (Macaca fusucata) were used in this study. The animals underwent Le Fort I osteotomy in their unilateral maxillae. Histological and angiographic examinations were performed to observe the postoperative changes in the maxillae and dental pulp. Postoperative pulpal blood flow was examined using a laser Doppler flowmetry. Postoperative pulpal blood flow, by a laser Doppler flowmetry, and dental pulp sensibility, by electrodiagnostics, in patients who underwent Le Fort I osteotomy, were also examined. Although nerve fibers observed in the dental pulp of the maxilla degenerated and disappeared by one week postoperatively, they reappeared sparsely from two to three months after osteotomy, and there were abundant nerve fibers by one year postoperatively. In the angiographic examination, blood supply to the maxillary dental pulp was maintained throughout the postoperative period. In the examinations of laser Doppler flowmetry and dental pulp electrodiagnostics, ischemia in the dental pulp for three or four days after osteotomy might delay the recovery of dental pulp sensibility. These results suggested that blood flow in dental pulp at three or four days after surgery may affect the recovery of dental pulp sensibility.

Evidence for the role of nitric oxide in the circulation of the dental pulp.

Many authors have studied the hemodynamics of the dental pulp; however, there are scarcely any data regarding the involvement of the L-arginine/nitric oxide pathway in the regulatory mechanism. Thus, we have examined the physiological effects of (1) NG-nitro-L-arginine as an inhibitor of nitric oxide synthesis and (2) the nitric oxide donor 3-morpholinosydnonimine on blood flow and vascular resistance in the canines of anesthetized cats to study the potential involvement of nitric oxide in the regulation of dental vascular homeostasis. Mean arterial blood pressure, heart rate, blood gases, pH, cardiac output, and tissue blood flow were determined prior to and 15 min after i.v. administration of either NG-nitro-L-arginine (30 mg/kg, n = 9) or 3-morpholinosydnonimine (1 mg/kg, n = 7). Blood flow was measured by radioactive-labeled microspheres. There were no significant differences in baseline parameters between the two groups of cats. The dental pulp blood flow decreased to 53 +/- 13% (p < 0.01) of the control level after NG-nitro-L-arginine administration, while it decreased only slightly (to 82 +/- 12%) after 3-morpholinosydnonimine administration. The dental pulp's vascular resistance increased to 367 +/- 69% (p < 0.01) of the control level after NG-nitro-L-arginine, while it decreased to 73 +/- 10% (p < 0.05) of control after 3-morpholinosydnonimine. We found that the L-arginine/nitric oxide pathway plays an important role in the regulation of pulpal blood circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of dental materials, alcohol and cigarettes on the blood flow in dog canine tooth pulp. Observation by the hydrogen gas clearance method.

It is commonly known that a certain amount of blood flow is required in the dental pulp to keep the teeth healthy. The amount of the blood flow in the dental pulp is an important factor in the growth of the jaw and teeth. The author studied the changes in the blood flow in dental pulp by applying the dentist's ordinary drugs, alcohol and cigarettes, which often directly touch the dental pulp when it is exposed. The untreated teeth opposite the treated ones were examined for comparison. The follwing results were obtained:1. Application of disinfectants such as Oxydol, Neocleaner and Rusnon caused a momentary decrease in the blood flow which lasted about twenty to thirty minutes before the flow was restored.2. Xylocaine, a local anaesthetic, caused a slight increase or a strong momentary decrease in the blood flow. When epinephrine was added to Xylocaine, the effect became apparent, that is, the blood flow clearly decreased.3. Calvital, a drug made of calcium hydroxide, and a solution of calcium hydroxide, both of which are used as preservatives for teeth, caused a strong momentary or lasting decrease in the blood flow. In cases where the effect lasted, the flow was not restored for more than three hours after the treatment. Two weeks afterwards, however, the blood flow was definitely greater than it had been before the application of these drugs.4. Acidulated fluoride solution, used for preventing dental caries, definitely decreased the blood flow on the treated side.5. Liquid detifrice, used as a dental hygienic drug, induced a momentary increase or decrease or no change in the blood flow. The color tester, plaque disclosing solution, had almost no effect on the blood flow.6. A solution of 20% Etyl alcohol caused a slight a momentary increase or a distinct momentary decrease in the blood flow. Aqueous extract solution of cigarettes brought about a very slight momentary increase or decrease in the blood flow.

Neuropeptide Y (NPY) and sympathetic control of blood flow in oral mucosa and dental pulp in the cat.

Neuropeptide Y (NPY) immunoreactivity (-IR) was found to be present in perivascular nerves in the cat dental pulp and oral mucosa. Many ganglion cells in the superior cervical ganglion also contained NPY-IR. Ligation of the inferior alveolar or lingual nerves produced an accumulation of NPY-IR in axons proximal to the site of ligation, suggesting an anterograde axonal transport of the peptide. After unilateral sympathectomy the NPY-IR disappeared in the dental pulp and oral mucosa on the ipsilateral side. Reversed phase high performance liquid chromatography showed that the main peak of NPY-like immunoreactivity found in the superior cervical ganglion co-chromatographed with synthetic porcine NPY. Changes in blood flow in dental pulp or oral mucosa were measured indirectly by recording local clearance of 125I during electrical stimulation of the sympathetic nerve or during close intra-arterial infusion of noradrenaline or NPY. All three procedures resulted in a pronounced decrease in local blood flow of a similar magnitude in both tissues. After alpha-adrenoceptor blockade with phentolamine, the vasoconstrictor effect of noradrenaline was abolished. However, the effect of sympathetic stimulation after phentolamine was only partially reduced (23-54%) and the response to NPY was almost unaffected by the alpha-receptor blockade. The remaining effect of sympathetic stimulation after phentolamine was abolished by guanethidine. However, the response to NPY was not changed by the latter drug. In conclusion, the vasoconstrictor response in the dental pulp and oral mucosa caused by activation of sympathetic nerves is more resistant to phentolamine than the response induced by infusion of exogenous noradrenaline. Since NPY is probably co-localized with noradrenaline in the sympathetic perivascular nerves and NPY reduces local blood flow, it is proposed that this peptide is involved in sympathetic vascular control in oral tissues.