Paul C. Montgomery

Electric currents, bone remodeling, and orthodontic tooth movement: II. Increase in rate of tooth movement and periodontal cyclic nucleotide levels by combined force and electric current☆

Piezoelectric currents in mechanically stressed bone were implicated in the activation of bone cells. The objectives of this experiment were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to study the effect of electric-orthodontic treatment on periodontal cyclic nucleotides. Maxillary canines were tipped in five cats by 80 g force. Two groups of five cats each were treated by an electric-orthodontic procedure to one maxillary canine for 7 and 14 days, respectively. Teeth treated by force and electricity moved significantly faster than those treated by force alone. Enhanced bone resorption was observed near the anode (PDL compression site), while bone formation was pronounced near the cathode (PDL tension site). Staining for cyclic nucleotides was increased when electric stimulation was added to the mechanical force. These results suggest that orthodontic tooth movement may be accelerated by the use of locally applied electric currents.

Electric currents, bone remodeling, and orthodontic tooth movement

Piezoelectric currents in mechanically stressed bone were implicated in the activation of bone cells. The objectives of this experiment were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to study the effect of electric-orthodontic treatment on periodontal cyclic nucleotides. Maxillary canines were tipped in five cats by 80 g force. Two groups of five cats each were treated by an electric-orthodontic procedure to one maxillary canine for 7 and 14 days, respectively. Teeth treated by force and electricity moved significantly faster than those treated by force alone. Enhanced bone resorption was observed near the anode (PDL compression site), while bone formation was pronounced near the cathode (PDL tension site). Staining for cyclic nucleotides was increased when electric stimulation was added to the mechanical force. These results suggest that orthodontic tooth movement may be accelerated by the use of locally applied electric currents.Osteogenesis has been found to occur in response to the application of electric currents to bone. The objective of this experiment was to study the effects of D.C. electric currents on periodontal tissues in cats. Cyclic nucleotides, compounds known to be involved in cellular activation, were studied by immunohistochemistry in the involved tissues. Three groups of three young adult cats each were treated for 1, 3, and 7 days, respectively, by a device delivering 15 microamperes of direct current to bone osteoblasts and PDL cells stained intensely for cAMP and cGMP were observed adjacent to the cathode and anode, and bone apposition was found near the cathode. These results suggest that electric stimulation enhances cellular enzymatic phosphorylation activities in periodontal tissues and may be a potent tool in accelerating alveolar bone turnover.

Biochemical mediators of the effects of mechanical forces and electric currents on mineralized tissues

SummaryCyclic nucleotides (cAMP and cGMP) and prostaglandin E (PGE) have been implicated as possible mediators of the effects of external stimuli on bone cells. The objective of this study was to determine changes in relative levels of these substances in mineralized tissue cells in response to mechanical and electrical stimuli, by the use of a combined immunohistochemical-microphotometric procedure. Canine teeth of eight 10–12 month-old female cats were tipped distally with 80 g force for either 1 h or 14 days. After 1 h, a slight elevation of staining intensity in alveolar bone osteoblasts and periodontal ligament (PDL) cells was observed at sites of tension and compression. After 14 days of treatment, this effect was markedly increased. Fifteen female cats, 10–12 months old, received electric stimulation (20 µ amperes d.c.) to the gingiva of 1 maxillary canine for 1, 5, 15, 30, or 60 min. At the cathode, significant increases of staining intensity in periosteal osteoblasts for cAMP, cGMP, and PGE were found at 15 and 60 min. At the anode, a significant rise in the staining intensity of these cells for PGE was seen at 15 min; at 60 min, cGMP and PGE, but not cAMP, were elevated. These results demonstrate the usefulness of the immunohistochemical technique in detecting relative changes in mineralized tissue cell content of cyclic nucleotides and prostaglandins in response to local application of physical stimuli of short and long duration.

Migration of IgA-bearing lymphocytes into salivary glands

Abstract The relative migratory properties of [125I]iododeoxyuridine-labeled dividing mesenteric lymph node (MLN) and peripheral lymph node (PLN) cells were assessed in mice using the adoptive transfer system. MLN cells from virgin donors showed a greater tendency to localize in MLN, small intestine, and mammary glands (lactating recipients only) of virgin and lactating recipients. In addition, MLN cells were shown to selectively localize in the salivary (submandibular and sublingual) glands. The relative migratory properties of MLN and PLN cell populations were identical when donor cells were obtained from virgin or lactating animals. Selective depletion of IgA-bearing cells from the MLN transfer cell population abrogated the preferential localization in control mucosal tissues and salivary glands. These data show that the salivary glands can be included as an additional mucosal area populated by gut-derived IgA-bearing cells and provides direct evidence that the common mucosal immune sytstem extends to secretory tissue in the oral cavity.

Cellular localization of cyclic AMP in periodontal tissues during experimental tooth movement in cats

Using an immune-histochemical method, cyclic AMP was localized in cells of periodontal tissues in orthodontically-treated cats. Sixteen cats were treated for periods ranging from 1 hour to 4 weeks. Fresh, frozen, undecalcified 6 μ sections of the tissues were incubated with rabbit anti-cyclic AMP antibodies, followed by sequential incubations with sheep anti-rabbit IgG, rabbit anti-peroxidase IgG and horseradish peroxidase. In the final step, the peroxidase was demonstrated by the diaminobenzidine (DAB) method. It was found that the number of intensely stained cells increased within a short time in areas in which bone resorption or apposition occurred later. However, differences in the pattern of cellular activation were found to exist between areas of compression and tension. The alveolar osteocytes appeared to be affected to only a slight degree by the applications of mechanical forces. These results indicate: (a) that our immune-histochemical method was useful in following the cellular distribution of cyclic AMP during bone remodeling; and (b) that mechanical forces may affect only a small part of the bone cell population and therefore cannot be regarded as an efficient means to bring about extensive bone remodeling.

The induction and characterization of secretory IgA antibodies.

In addition to humoral immunity, which is characterized by the presence of circulating antibody, a second distinct type of immunity involves the localized production of secretory antibodies (reviews 1,2,3). Numerous investigators, employing different antigens in a wide variety of animal systems, have been able to stimulate localized antibody production (4–13). The characteristic structural features of secretory IgA (review 3), which allows it to be differentiated from its serum counterpart, make IgA the ideal immunoglobulin class to be used in studies on the inductive process. Of particular relevance to our current studies was the demonstration that local immunization, by the intramammary route, with either dinitrophenylated bovine gamma globulin (6) or group A streptococci (8) could induce specific colostral IgA antibodies. Other evidence strongly suggested that gut associated lymphoid tissue was not only involved in the production of intestinal IgA antibodies (5, 9, 11, 13), but also might play a role in IgA production at remote sites (7, 9, 10, 12) including secretory sites (10, 12, 14).

Remote-Site Stimulation of Secretory IgA Antibodies Following Bronchial and Gastric Stimulation

The induction of secretory antibodies remains a complex subject with a variety of factors being important: 1) choice of the animal model, 2) the nature of the antigenic stimulus and 3) the method of immunization. Our own investigations have utilized the pregnant rabbit and various DNP-carrier conjugates to probe the manner by which secretory antibodies, particularly secretory (s) IgA, were induced in mammary glands (1–3). These studies demonstrated that: 1) local (intramammary) administration of antigen was effective at reproducibly eliciting s-IgA antibodies (confirming earlier studies (4,5), 2) there was a lack of correlation between the induction of high levels of s-IgA antibodies and serum IgG antibodies, 3) there appeared to be a special relationship between gastrointestinal stimulation and remote-site (mammary) production of s-IgA antibodies, and 4) gastrointestinal stimulation of s-IgA antibodies in milk was not blocked by high levels of circulating IgG serum antibodies. Additional evidence suggested that a similar “remote-site” stimulation phenomenon also existed in other animal species.

Demonstration of cyclic AMP in bone cells by immuno-histochemical methods

By utilizing immunohistochemical procedures it was possible to locate bone cells that contained adenosine 3′5′-monophosphate (cyclic AMP) in frozen, undecalcified cat jaw sections. An immunoglobulin-enzyme bridge method was found to be superior to other techniques, including immunofluorescence. Differences in staining pattern were found between bone cells of kittens and young adult cats, indicating different metabolic levels related to cellular maturity, and different intracellular compartmentalization of cyclic AMP in the two age groups.

Immunohistochemical localization and distribution of cyclic nucleotides in the rat mandibular condyle in response to an induced occlusal change.

Cyclic AMP and guanosine 3′:5′-monophosphate (cGMP) are involved in the regulation of cell proliferation in vitro. A unilateral occlusal splint 1 mm high was fabricated on the maxillary right posterior teeth of adult male rats. Animals were treated for 0, 6, 12, 24 hr and 7 days. Serial sagittal sections of fresh-frozen, unfixed, undemineralized jaws were processed immunohistochemically for localization of cAMP and cGMP. In the control condylar cartilage, the cells in both intermediate (I) and hypertrophie (H) zones stained uniformly for cAMP. In the treated condyle, the cells in I showed less cAMP staining at 6 and 12 h and a marked reduction at 24 h. The staining pattern for cGMP in the control was generally weak with noticeable deposits at the cell periphery. In the treated condyle, the cells in I stained intensely for cGMP at 12 and 24 h. The staining pattern and intensity for cyclic nucleotides in H was almost unaffected by the change in occlusion. Occlusal alterations thus affect the activity of the condylar cartilage cells preferentially in the intermediate zone. The rapid decline of cAMP- and elevation of cGMP staining intensity suggests that these nucleotides play a significant role in condylar cell proliferation in vivo.

Selective Transport of an Oligomeric Iga Into Canine Saliva

Evidence is presented which shows that an oligomeric IgA myeloma protein possessing J-chain but lacking secretory component, is selectively transferred from serum into canine saliva. The data also demonstrate that 125I-label remains with the IgA during the transfer process. These data interpreted in the light of findings in humans support the concept that the oligomeric form of IgA, devoid of secretory component, is required to achieve selective transport.