Alkaline phosphatase activity in normal and inflamed dental pulps

Alkaline phosphatase (ALP) seems to be important in the formation of mineralized tissues. High levels of ALP have been demonstrated in dental pulp cells. In the present study ALP activity was analyzed in normal healthy human dental pulps, in reversible pulpitis, and in irreversible pulpitis. Enzymatic ALP control values for the normal healthy pulps were 110.96+/-20.93. In the reversible pulpitis specimens the ALP activity increased almost eight times to 853.6+/-148.27. In the irreversible pulpitis specimens the values decreased sharply to 137.15+/-21.28 and were roughly equivalent to those seen in normal healthy pulps. The differences between the groups (control vs. reversible pulpitis and reversible pulpitis vs. irreversible pulpitis) were statistically significant. These results could point to a role of ALP in the initial pulp response after injury.     

Alkaline phosphatase in the enamel organ of the rat incisor

abstract — The distribution of alkaline phosphatase in the enamel organ of the rat incisor was histochemically investigated using α-naphthyl phosphate as the substrate. During the stage of enamel matrix formation the enzyme activity was found mainly in the stratum intermedium, while during the stage of enamel maturation the activity was evenly distributed within the enamel organ. The biochemical properties of alkaline phosphatase, using paranitrophenyl phosphate as the substrate, were studied. The pH optimum of the enzyme was found to be about 10. The heat inactivation of alkaline phosphatase from the enamel organ was found to be similar to the behavior of bone and odontoblast phosphatase. Mg²⁺ activated the enzyme, while Ca²⁺, PO₄³⁻ and F⁻ inhibited the enzyme. The effect of urea on the enzyme activity was similar to the behavior of bone and odontoblast phosphatase. EDTA treatment resulted in a marked inhibition of the activity of alkaline phosphatase. It was concluded that there was no detectable difference in biochemical behavior between alkaline phosphatase in the stage of matrix formation and the stage of enamel maturation. It was also concluded that alkaline phosphatase from the enamel organ is similar to the alkaline phosphatase from bone and odontoblasts.     

Alkaline phosphatase activity and tetracycline incorporation during initial orthodontic tooth movement in rats

The activity of alkaline phosphatase and the incorporation of tetracycline as signs of bone formation were studied after orthodontic tooth movement for 10 h to 6 days in rats. Defined low or high forces were used. A moderate activity of non-specific alkaline phosphatase was found in the periodontal membrane (PDM) in untreated rats and in rats treated with low forces. In addition, all bone surfaces were outlined with a narrow band of intense non-specific alkaline phosphatase activity that was vanadate- and levamisole-resistant. Likewise, tetracycline was incorporated on all bone surfaces. The bone formation rate was low and uniform within the alveolus, indicating that no intra-alveolar drift of the molar occurred in the untreated rats. Orthodontic forces gradually inhibited vanadate- and levamisole-resistant alkaline phosphatases and tetracycline incorporation on the bone surfaces in the pressure zones of the PDM, depending on the magnitude of the force. It was suggested that the disappearance of these isoenzymes, in a limited area, as seen in the pressure zones, was associated with inhibited bone formation and subsequent initiation of bone resorption. On the tension side a slight reduction and redistribution of vanadate- and levamisole-resistant alkaline phosphatase activity could be noted irrespective of the magnitude of the applied force.     

Alkaline phosphatase activity in a strain of Bacterionema matruchotii.

Protein from the soluble fraction of Bacterium matruchotii cells propagated in a medium containing no added inorganic phosphate was fractionated by gel permeation chromatography. The bulk of phosphatase activity assayed at pH 8.0 was found in fractions equivalent to a molecular weight of 6 x 10(5) daltons. Substrate saturation kinetics indicate at Km of 0.75 mM for p-nitrophenylphosphate. Activity was stimulated more than two-fold by Zn++ at 1 mM, but was significantly reduced by EDTA, Ca++ and inorganic phosphate. The enzyme(s) shows negligible activity at pH below 6.0 and has a narrow optimum between 7.5 and 8.5.     

Alkaline phosphatase activity in dental pulp of orthodontically treated teeth.

INTRODUCTION: The aim of this study was to examine alkaline phosphatase (ALP) activity in the dental pulp of orthodontically treated teeth. METHODS: Sixteen healthy subjects (mean age 17.0 +/-1.6 years) who required extraction of 4 first premolars for orthodontic reasons participated. One maxillary first premolar subjected to orthodontic force was the test tooth. The contralateral first premolar, bracketed but not subjected to mechanical stress, was the control tooth. After a week of treatment, the first premolars were extracted and the dental pulp removed from the teeth. ALP activity was determined spectrophotometrically and the results expressed as units/liter per milligram of pulp tissue [U/(L x mg)]. RESULTS: ALP activity was 89 +/- 26 U/(L x mg) in the test teeth and 142 +/- 33 U/(L x mg) in the control teeth. The difference between the groups was statistically significant (P < .01). CONCLUSIONS: Orthodontic treatment can lead to significant early-phase reduction in ALP activity in human dental pulp tissue.     

Influence of cations on enamel phosphatase activity

ATP and 5-Br-4-Cl-indoxyl phosphate were used as substrates for spectrophotometric measurement of phosphatase activity in partly mineralized bovine enamel. MgCl2, CaCl2, NaCl, and KCl were used as moderators of the enzyme activities. It is concluded that at least two phosphatases, active at alkaline pH, are present in the immature enamel matrix.     

Alkaline and acid phosphatase activity in the dynamics of ectopic osteogenesis]

Activities of marker enzymes of osteoblasts (alkaline phosphatase), osteoclasts (tartrate-resistant isoform of acid phosphatase), and macrophages (tartrate-sensitive isoform of acid phosphatase) in bone tissue forming after osteoinduction on the basis of demineralized bone matrix were under study. Early (1 week) stages of osteosynthesis were characterized by low activity of alkaline phosphatase, acid phosphatase being represented by the tartrate-sensitive isoform. Two-three weeks later alkaline phosphatase activity grew and the tartrate-resistant isoform of acid phosphatase appeared. By the fourth-sixth weeks of osteogenesis alkaline phosphatase activity stabilized at a certain level and acid phosphatase activity still grew at the expense of the tartrate-resistant isoform. Conformity of the enzymologic data to changes in cellular populations in ectopic osteogenesis is discussed.     

Alkaline phosphatase activity in gingival crevicular fluid during human orthodontic tooth movement.

Bone remodeling that occurs during orthodontic tooth movement is a biologic process involving an acute inflammatory response in periodontal tissues. A sequence characterized by periods of activation, resorption, reversal, and formation has been recently described as occurring in both tension and compression tooth sites during orthodontic tooth movement. We used a longitudinal design to investigate alkaline phosphatase (ALP) activity in gingival crevicular fluid (GCF) to assess whether it can serve as a diagnostic aid in orthodontics. Sixteen patients (mean age, 15.5 years) participated in the study. The maxillary first molars under treatment served as the test teeth (TT) in each patient; in particular, 1 first molar was to be retracted and hence was considered the distalized molar (DM), whereas the contralateral molar (CM) was included in the fixed orthodontic appliance but was not subjected to the distal forces. The DM antagonist first molar (AM), free from any orthodontic appliance, was used as the baseline control. The GCF around the experimental teeth was harvested from mesial and distal tooth sites immediately before appliance activation, 1 hour after, and weekly over the following 4 weeks. The clinical gingival condition was evaluated at the baseline and at the end of the experimental term. ALP activity was determined spectrophotometrically at 30 degrees C, and the results were expressed as total ALP activity (mUnits/sample). GCF ALP activity was significantly elevated in the DMs and the CMs as compared with the AMs at 1, 2, 3, and 4 weeks; conversely, in the AMs, GCF ALP activity remained at baseline levels throughout the experiment. Moreover, the enzyme activity in the DMs was significantly greater than in the CMs. In the DMs, a significantly greater ALP activity was observed in sites of tension compared with sites of compression. This difference was not seen with the CMs, in which the enzyme activity increased to the same extent in tension and compression sites. These results suggest that ALP activity in GCF reflects the biologic activity in the periodontium during orthodontic movement and therefore should be further investigated as a diagnostic tool for monitoring orthodontic tooth movement in clinical practice.     

Alkaline phosphatase activity in gingival crevicular fluid during canine retraction

OBJECTIVES: The aim of the study was to investigate alkaline phosphatase activity in the gingival crevicular fluid (GCF) during orthodontic tooth movement in humans. SETTING AND SAMPLE POPULATION: Postgraduate orthodontic clinic. Ten female patients requiring all first premolar extractions were selected and treated with standard edgewise mechanotherapy. EXPERIMENTAL VARIABLE: Canine retraction was done using 100 g sentalloy springs. Maxillary canine on one side acted as experimental site while the contralateral canine acted as control. OUTCOME MEASURE: Gingival crevicular fluid was collected from mesial and distal of canines before initiation of canine retraction (baseline), immediately after initiation of retraction, and on 1st, 7th, 14th and 21st day and the alkaline phosphatase activity was estimated. RESULTS: The results show significant (p < 0.05) changes in alkaline phosphatase activity on the 7th, 14th and 21st day on both mesial and distal aspects of the compared experimental and control sides. The peak in enzyme activity occurred on the 14th day of initiation of retraction followed by a significant fall in activity especially on the mesial aspect. CONCLUSIONS: The study showed that alkaline phosphatase activity could be successfully estimated in the GCF using calorimetric estimation assay kits. The enzyme activity showed variation according to the amount of tooth movement.     

Alkaline phosphatase activity is upregulated in regenerating human periodontal cells

The activity of alkaline phosphatase (ALP) is considered to indicate the presence of osteoblast cells and the formation of new bone. In the present study this enzyme was investigated in cells obtained from retrieved polytetrafluoroethylene membranes (M cells) of periodontal disease patients treated by guided tissue regeneration (GTR) and from the regenerated tissue underlying the membrane (RT cells). Normal periodontal ligament (PL) and gingival cells were also grown from the corresponding healthy tissues of human subjects. ALP activity was measured colourimetrically, using paranitrophenyl phosphate as the substrate, after 4 and 7 d of culture in the absence and presence of dexamethasone (DEX), a synthetic glucocorticoid which induces osteoblast differentiation. The results showed that basal levels of ALP activity were expressed by all the cells and that DEX upregulated ALP levels in the M, RT and PL cells but not in the gingival cells. Moreover, both the basal and DEX-induced ALP activities were statistically significantly higher in the RT cells than in any of the other cells. Our results suggest that both the GTR-associated and normal PL cells express osteoblast-like characteristics and, furthermore, that the RT cultures in particular contain a high proportion of osteoprogenitor cells.     

Alkaline phosphatase isozyme activity in serum from patients with chronic periodontitis

BACKGROUND: High alkaline phosphatase activity (ALP) is shown in the periodontal ligament due to the constant renewal of this tissue or pathological circumstances. We have previously shown that the activity level of this enzyme could be reflected at the serum level. OBJECTIVES: Because the local production of ALP in the periodontal ligament is often of the bone-type enzyme, we studied the activity of this isozyme among the other isoforms in the serum of patients with chronic periodontitis in comparison with that of control subjects. MATERIAL AND METHODS: This study included 83 patients (59 with periodontal disease, 24 as control group) and we determined the total seric ALP activity and the percentage of the different isoforms (essentially bone, kidney and intestinal-types) by Ektachem analyser and gel agarose electrophoresis respectively. CONCLUSIONS: By comparisons between the two groups, our results showed a relationship between loss of attachment in periodontal disease and a drop in bone ALP activity in serum. Moreover, these results suggested a gender based difference as well, with lower activity more frequent in women than in men.     

Effects of orthodontic force on enamel formation in normal and hypocalcemic rats

Maxillary incisors of young rats fed a diet deficient in calcium and vitamin D for 4 weeks developed hypoplastic enamel surfaces. In the enamel of maxillary incisors of deficiently fed rats as well as in normal rats, an orthodontic force (50 gin) acting on their incisors for 3–7 days induced foldings in the enamel, globular projections from the surface and marked hypoplastic defects. However, the orthodontic force produced clusters of free-lying enamel matrix only in the nutritionally deficient rats. In view of these observations, it might be concluded that disturbances in enamel formation which cause hypoplasias can he caused both by mechanical trauma and hypocalcemia. Furthermore, it seems that hypocalcemia increases the susceptibility to mechanical trauma of ameloblasts in their secretory stage. Whether the changes in enamel formation noted in the hypocalcemic rats is a direct effect of lowered serum calcium or due to the increase in parathyroid hormone is not known at present.     

Effects of orthodontic force on enamel formation in normal and hypocalcemic rats

Maxillary incisors of young rats fed a diet deficient in calcium and vitamin D for 4 weeks developed hypoplastic enamel surfaces. In the enamel of maxillary incisors of deficiently fed rats as well as in normal rats, an orthodontic force (50 gm) acting on their incisors for 3-7 days induced foldings in the enamel, globular projections from the surface and marked hypoplastic defects. However, the orthodontic force produced clusters of free-lying enamel matrix only in the nutritionally deficient rats. In view of these observations, it might be concluded that disturbances in enamel formation which cause hypoplasias can be caused both by mechanical trauma and hypocalcemia. Furthermore, it seems that hypocalcemia increases the susceptibility to mechanical trauma of ameloblasts in their secretory stage. Whether the changes in enamel formation noted in the hypocalcemic rats is a direct effect of lowered serum calcium or due to the increase in parathyroid hormone is not known at present.     

The effects of inorganic ions situated at the enamel surface on the adsorption and activity of acid phosphatase.

This study has demonstrated, first, that the affinity of the enamel surface for a biologically active protein-in this case, acid phosphatase-may be modified by first impregnating the mineral with particular inorganic ions. Second, enzymic activity is altered as a function of the inorganic ion incorporated into the enamel surface. Third, strong inhibition of acid phosphatase is demonstrated by ions expected to be released during the carious process which contradicts the postulation that phosphatases are actively hydrolyzing enamel matrix-bound phosphate during the carious attack. Fourth, these results suggest that by incorporating a particular ion into the enamel mineral, a surface with assigned properties may be created which offers some degree of control over subsequent adsorption of organic matter. Thus, it is apparent that by proper selection of inorganic ions and organic macromolecules, both structural properties and biological activities at the enamel-oral fluid interface may be predictably modified.