ORIGINAL RESEARCH
Year : 2023 | Volume
: 34 | Issue : 1 | Page : 14--18
Calcitonin as a pharmacological anchorage in orthodontics
Patrcia M Pizzo-Reis1, Monica C Coêlho2, Ricardo B Azevedo3, Jorge Faber4,
1 Department of Orthodontics, School of Health Sciences, University of Brasília, Albany Medical Center, Brasília, DF, Brazil
2 Department of Orthodontics, Bueno Dental Clinic, Goiânia, GO, Brazil
3 Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasília, Brasília, DF, Brazil
4 Graduate Program in Dentistry, School of Health Sciences, University of Brasília, Brasília, DF, Brazil
Correspondence Address:
Patrcia M Pizzo-Reis
Albany Medical Center, Rua 5 Norte, Lote 3, Sala 414, Aguas Claras, 71907-720, Brasilia, DF
Brazil
Abstract
Objective: This study aimed to evaluate the effects of salmon calcitonin administration as a pharmacological anchoring agent in orthodontics and to determine the influence of locally applied calcitonin on serum calcium levels. The secondary aim was to observe the response of dental and periodontal tissues using light microscopy. Methods: Fourteen healthy male adult Wistar rats with an average weight of 250 g had their teeth moved, seven of which received a local injection of salmon calcitonin in the furcation region of the left upper first molar. Concurrently, the remaining seven were used as controls. In the control group, saline solution was injected in the bifurcation region of tooth 26 to subject these animals to the same stress level as those of the experimental group. After 14 days, a 6 mm diameter orthodontic elastic band was inserted between teeth 26 and 27 in all animals to induce the movement of these teeth. The rats were anaesthetised and exsanguinated on day 21. In both groups, tooth movement and serum calcium levels were measured. The jaws were dissected with straight scissors, and tissue blocks containing gingiva, bone and teeth were identified, fixed and demineralised. Then, the pieces were cut into semi-serial slices, stained with hematoxylin, eosin, and Mallory's trichrome, and analysed under an Axiophot light microscope. Results: There was significantly less tooth movement in the experimental group (X̄; 0,150 mm ± 0,037) than in the control group (0,236 mm ± 0,044; P = 0,003), while there was no significant difference in serum calcium levels between the two groups (controlX̄; 9,53 mg/dl ± 1,53; experimental 10,81 mg/dl ± 1,47; P = 0,15). Conclusion: While calcitonin did not completely inhibit osteoclast activity, it promoted orthodontic anchorage, apparently, by local action.
How to cite this article:
Pizzo-Reis PM, Coêlho MC, Azevedo RB, Faber J. Calcitonin as a pharmacological anchorage in orthodontics.Indian J Dent Res 2023;34:14-18
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How to cite this URL:
Pizzo-Reis PM, Coêlho MC, Azevedo RB, Faber J. Calcitonin as a pharmacological anchorage in orthodontics. Indian J Dent Res [serial online] 2023 [cited 2023 Sep 29 ];34:14-18
Available from: https://www.ijdr.in/text.asp?2023/34/1/14/380515 |
Full Text
Introduction
Adequate anchorage has been recognised as a key element in the success of orthodontic treatment since the beginning of modern orthodontics. The evolution of anchorage devices seems to have remained at the forefront of orthodontics, more so than the evolution of brackets or archwires, even though these products have a significant commercial appeal. This evolution has been driven not only by efficacy but also by patients' willingness to use the devices. Some anchorage devices require extensive cooperation from the patient, sometimes with esthetic limitations and the volume they occupy inside and, eventually, outside the oral cavity. Thus, there is a demand for less visible and more comfortable anchorage devices and accessories. Consequently, devices such as Kloehn's headgear have become less common in clinical practice, even though they are excellent biomechanical options for various conditions.
Skeletal anchorage (SA) emerged due to this demand for less intrusive and more comfortable anchorage devices. In addition to being highly effective and requiring low levels of patient cooperation, SA is typically intraoral and reasonably comfortable.[1] SA was developed for use with fixed apparatuses, expanded the limits of tooth movement without regard for patient compliance and collaboration and allowed good control over tooth movement in the three planes of space.[1],[2]
In recent years, the compatibility of functional gains of treatment with esthetic devices has been increasingly valued by patients, culminating in the rise of orthodontic aligners. During the current digital age, it may be inadvisable to deny the esthetic desires of patients in favour of more classic and “visible” orthodontia. Therefore, there is a need to develop anchorage tools that combine the high esthetics of aligners with patients' comfort when using the device.
There is one possible anchorage option that has received little attention in the field of orthodontics: pharmacological anchoring. Different drugs can alter the bone remodelling cycle, influencing osteoclast function and tooth movement. Thus, they could provide maximal anchorage while preventing undesired movements. In this technique, instead of using a mechanical device, medication decreases osteoclastic activity and thus controls tooth movement at the tissue level. If pharmacological agents can successfully be used for anchorage, orthodontics may become more attractive to many who are reluctant to undergo treatment because they may need a fixed element such as a miniscrew or miniplate. One candidate for a pharmacological anchorage agent is calcitonin. This hormone, capable of influencing bone density, is a potent inhibitor of osteoclasts which exerts its effects through a receptor on their surface.[3] Calcitonin inhibits the formation of actin rings, a cytostructure necessary for the bone resorption activity of osteoclasts,[4],[5] in addition to having a positive effect on osteoblasts,[6] suggesting that it could be used in limiting bone resorption, subsequently keeping teeth in their original positions. The binding of calcitonin to its receptors on osteoclasts has significant and immediate consequences. Within a few minutes, cell retraction occurs with the suspension of cell motility and subsequent interruption of bone resorption.[7]
Testing this theory involves verifying whether or not this hormone can reduce the magnitude of tooth movement at the application site. Thus, the primary aim of this study was to evaluate the effect of the administration of salmon calcitonin in rats as a pharmacological anchorage agent in orthodontics and to determine how far the local administration of calcitonin could influence the serum calcium too in the bloodstream. The secondary aim was to observe the response of dental and periodontal tissues using light microscopy.
Material and Methods
This study was approved by the Ethics Committee of Human and Animal Medical Research at the Federal University of Goiás (CEHC/UFG2001-021).
Fourteen healthy male adult Wistar rats with an average weight of 250 g were used for the present study. They were acclimated to the experimental laboratory in the vivarium and kept at a constant temperature in community plastic cages lined with sawdust under a cycle of natural light. The animals received standard rodent food (Labina-Purina®) and water at will and were weighed daily. All necessary interventions were performed under anaesthetic sedation via intramuscular administration of ketamine solution (Dopalen®), 0.08 mL/100 g of the animal's body weight, and acepromazine (Acepran®), 0.04 mL/100 g of the animal's body weight, in the outer region of the animals' thighs.
Clinical laboratory procedures
The animals were divided into two groups of seven animals each: control and experimental groups. In both groups, the left side of the maxilla was used to induce tooth movement using the methods described by Waldo and Rothblatt.[8] Initially, each animal in the experimental group received a periosteal injection of 0.01 mL of 100 UI/mL salmon calcitonin solution (Miacalcic®) using a 0.1 mL syringe and a 12.7 mm × 0.33 mm needle in the bifurcation region of tooth 26 to inhibit resorption in that area, before the induction of orthodontic movement. In the control group, saline (0.01 mL) was injected in the bifurcation region of tooth 26 to subject these animals to the same stress level as those of the experimental group.
After 14 days, a 6 mm diameter orthodontic elastic band (11,101.06 GAC Orthomax®) was inserted between teeth 26 and 27 [Figure 1] in all animals to induce movement of these teeth. All animals were examined daily to check if the elastic bands were still present; if not, the elastic bands were replaced. The rats were anaesthetised and exsanguinated on day 21, using a 5 mL syringe and a 5 cm × 0.7 mm needle to collect plasma with heparin. Serum calcium levels were measured using a colorimetric method with o-Cresolphthalein complexone. This study aimed to determine whether calcitonin, when administered locally, could also influence calcium levels in the bloodstream. Calcium reacts with o-Cresolphthalein complexone (phthalate purple) in an alkaline medium, forming an intensely stained complex with maximum absorption at 570 nm. The 570 nm absorption of the complex is proportional to the concentration of calcium in the sample.
The jaws were dissected with a straight scissor and separated from the rest of the skull in sections distal to the third molars and mesial to the first molars. Tissue blocks containing gingiva, bone, and teeth were identified and fixed in a 4% paraformaldehyde solution buffered with 0.1M sodium phosphate (pH 7.4) for 12 h, and the elastic bands were removed.{Figure 1}
Tooth movement measurement
A millimetre ruler and the teeth from each tissue block were photographed under a standardised 8X magnification using a magnifying glass (Stemi SU11, Zeiss, Germany). Photographs were obtained orthogonally along the long axis of the ruler and the occlusal plane of the tissue blocks. A calliper was used to measure the distance between the distal surface of the upper first molar and the mesial surface of the upper second molar on the right and left sides of the mouth in both the control and experimental groups (505-646, Mitutoyo, Japan) [Figure 2].{Figure 2}
Histopathological Laboratory Procedures
The tissue blocks were demineralised in 5% hydrochloric acid for approximately 48 h. Then, the pieces were washed in running tap water for 1 min, dehydrated in increasing ethanol concentrations (70%, 80%, 90%, and 100%), diaphanous in xylene, and embedded in paraffin. The blocks obtained were cut into 8 μm semi-serial sections in a sagittal orientation, stained with hematoxylin, eosin, and Mallory's trichrome, and analysed under an Axiophot light microscope (Carl Zeiss, Germany).
Statistical analysis
For statistical analysis, SPSS v26.0 (IBM Corp, Armonk, NY, USA) was used, with a statistically significant P value of 5%. Descriptive statistics were performed for tooth movement and serum calcium levels. After determining the normality of the sample, t-tests were used to test the null hypothesis that there were no differences in tooth movement and serum calcium levels between the control and experimental groups.
Results
One animal in the experimental group died due to anaesthesia-induced respiratory failure. All other animals maintained their baseline weight and evolved well over the 21 days.
Tooth movement was significantly lower (36.4%) in the experimental group (x̄; 0.150 mm ± 0.037) than in the control group (0.236 mm ± 0.044; P = 0.003). [Figure 3]a shows the data distribution of the two groups.{Figure 3}
There was no significant difference in the serum calcium level between the control (x̄; 9.53 mg/dl ± 1.53) and experimental (10.81 mg/dl ± 1.47; P = 0.15) groups. The data distributions in the two groups are shown in [Figure 3]b.
Histological changes in periodontal tissue
On the non-moved (right) side of the maxilla in the control and experimental groups, the interdental papillae and supporting periodontium in the interdental spaces between the first and second molars were intact and exhibited normal characteristics.
On the left side of the control group, we observed spaces between the first and second molars produced by the elastic bands. None of the animals had interdental papillae in this region, and acute inflammatory infiltrates were present in these areas. These infiltrates extended towards the distal roots of the first molars [Figure 4]A and the mesial roots of the second molars surrounding them. Extensive acute inflammatory infiltrates were observed in the peripheries of the bony septa, which in most sections manifested as bony islands between the two roots [Figure 4]B. The bone tissues in the furcation regions of the first molars were disorganised and actively undergoing resorption processes. Moreover, numerous active osteoclasts were identified in the periphery of the bone trabeculae [Figure 4]C.{Figure 4}
On the moved (left) side of the experimental group, panoramic views of the area between the first and second molars showed remodelling regions, with resorption of bony ridges. However, osteoclastic activity in these regions was lower in the experimental group than in the control group. The interdental papillae were present in a few cuts, and the fibres ruptured [Figure 5]A. An amplified view showed numerous macrophages, small hemorrhagic infiltrates, and the presence of several osteoclasts [Figure 5]B. The second molars had moved posteriorly and remodelled the interdental septa.{Figure 5}
Consequently, numerous osteoclasts were present during active bone resorption. A few areas of tooth resorption were also identified [Figure 5]C. The bony ridges showed signs of resorption in the first molar furcation regions, close to where the calcitonin was injected, with acute inflammatory infiltrates being highly evident in the central areas [Figure 5]D. Several osteoclasts reabsorbed the bony ridges [Figure 5]E and areas of acute inflammatory infiltrate [Figure 5]F.
Discussion
The experimental group showed variations in serum calcium levels similar to those seen in the control group, indicating that the local administration of calcitonin did not influence serum calcium levels [Figure 3]b. This data is relevant because the eventual application of calcitonin as a pharmacological anchorage agent would require a primarily local action without systemic impacts that might inappropriately interfere with the process of bone turnover.[9] Calcitonin may be effective in inhibiting the release of calcium and phosphate,[9] but only when systemically administered for treating diseases related to bone resorption and the subsequent loss of minerals.
Although calcitonin is found in several species, salmon is its most widely used animal source. The following characteristics make it highly potent: long half-life, resistance to plasma degradation, and high affinity for specific receptors.[10],[11] In the present study, an elastic band was inserted only into the left hemiarch of the maxillae of the animals to allow a comparative evaluation with the unaffected (right) hemiarch. Moreover, this technique aimed to determine whether calcitonin would modify the opposite side from which it was injected, which led us to choose the right hemiarch as the control (non-moved) side. The periodontium showed typical characteristics in both groups on the control side. It appeared that the calcitonin injected on the left side of the experimental group was a small enough dosage not to influence the alveolar bone on the control side. This suggests that the calcitonin injected in the furcation region only acts locally without a significant histopathological impact on light microscopy of the opposite hemiarch (non-moved side).
In the present study, Waldo and Rothblatt's[8] method was used as described by the authors and efficiently promoted molar movement by applying a continuous load on the teeth. Animal models of tooth movement have been used for more than 100 years[12] using different force systems.[13] However, some complicating factors in forced tooth movement in animals, such as the breaking or deformation of devices during chewing, the type of force used, the way of measuring movement, and the differentiation of changes resulting from the treatment arising from craniofacial growth. An advantage of the model used in the present study was the relatively short treatment time (21 days), which mitigates some of the aforementioned effects, such as growth. However, it does not allow the inference that the difference between the movements found would not dissipate with time. This should be evaluated in future experiments with more prolonged treatment periods.
A limitation of the model used in the present study was the force applied. It was larger than needed to simulate orthodontic tooth movement performed at the clinic fully. However, this limitation did not prevent testing of the potential of calcitonin as a pharmacological anchorage agent. Tooth movement led to an acute inflammatory process and the recruitment of macrophages and osteoclasts in the areas between the first and second molars in both the control group [Figure 4] and the experimental group [Figure 5]. The decreased osteoclastic activity in the experimental group was significant, and similar findings have been previously described.[14] A decrease in bone resorption with the application of calcitonin was also observed by Guan L. et al.,[15] who also observed a dose-dependent decrease in the number of osteoclasts around the root and alveolar bone on the moved side, based on the concentration of the hormone, in addition to observing a decrease in tooth movement.
Decreased tooth movement was the primary result of this study. The experimental group, which received calcitonin, showed 36.4% less tooth movement than the control group (P = 0.003) due to decreased osteoclastic activity. This suggests a positive effect of calcitonin on the anchorage of teeth subjected to orthodontic forces.
Although orthodontic treatments require bone resorption for tooth movement to occur, treatment planning often requires that some teeth be kept close to their initial positions to serve as anchors for the movement of other teeth. The results of the present study indicate that salmon calcitonin is a promising target for future use as a pharmacological orthodontic anchorage. Further animal studies are necessary to establish the most appropriate dosages of calcitonin for anchorage and the safety of the drug for this purpose before any clinical trials start. The authors envision a possible clinical application in the future, with a subperiosteal injection of the drug directly using a needle and syringe or by resorbable submucosal implants that gradually release calcitonin.
Conclusions
Under the experimental conditions reviewed in the present study, the use of salmon calcitonin decreased the amount of orthodontic tooth movement by 36.4%. Local administration of calcitonin did not change the serum calcium levels in the experimental group when compared to the control group. The results of the present study indicate that salmon calcitonin is a promising target for future use as a pharmacological orthodontic anchorage.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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